Aviation Structural Mechanic S 3 2

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WILS
GOVU
D 207.208/2 : AV 5/9
AVIATION
STRUCTURAL MECHANIC S 3 & 2

NAVAL TRAINING COMMAND
RATE TRAINING MANUAL NAVTRA 10308 - C
)
PREFACE
This Rate Training Manual is one of a series of training manuals prepared
for enlisted personnel of the Navy and Naval Reserve who are studying for
advancement in the Aviation Structural Mechanic S (AMS) rating. As
indicated by the title , the manual is based on the professional qualifications
for the rates AMS3 and AMS2 , as set forth in the Manual of Qualifications
for Advancement, NavPers 18068 ( Series) . A reading list , which includes
USAFI texts recommended as study material for AMS personnel , is provided
in the front of the manual .
Combined with the necessary practical experience , the completion of this
manual will greatly assist the AMSAN and AMS3 in preparing for
advancement . This training manual should also be valuable as a review source
for the more senior rates .
This training manual was prepared by the Navy Training Publications
Center, NAS Memphis, Millington , Tennessee , for the Chief of Naval
Training . Technical review of the manuscript was provided by personnel of
the AMS( A) School , NAS Memphis, Millington , Tennessee ; the Naval
Examining Center , Great Lakes, Illinois ; and the Naval Aviation Integrated
Logistic Support Center, Patuxent River, Maryland. Technical assistance was
also provided by the Naval Air Systems Command .
i
THE UNITED STATES NAVY
GUARDIAN OF OUR COUNTRY
The United States Navy is responsible for maintaining control of the sea
and is a ready force on watch at home and overseas , capable of strong
action to preserve the peace or of instant offensive action to win in war .
It is upon the maintenance of this control that our country's glorious

future depends ; the United States Navy exists to make it so .
WE SERVE WITH HONOR
Tradition , valor , and victory are the Navy's heritage from the past . To
these may be added dedication , discipline, and vigilance as the watchwords
of the present and the future .
At home or on distant stations we serve with pride , confident in the respect

of our country , our shipmates , and our families .
Our responsibilities sober us ; our adversities strengthen us .
Service to God and Country is our special privilege . We serve with honor .
THE FUTURE OF THE NAVY

The Navy will always employ new weapons , new techniques , and
greater power to protect and defend the United States on the sea , under
the sea , and in the air .
Now and in the future , control of the sea gives the United States her
greatest advantage for the maintenance of peace and for victory in war .
Mobility , surprise , dispersal , and offensive power are the keynotes of
.
the new Navy . The roots of the Navy lie in a strong belief in the
future , in continued dedication to our tasks , and in reflection on our
heritage from the past .
Never have our opportunities and our responsibilities been greater.
ii
CONTENTS
Chapter Page
1. Aviation Structural Mechanic S rating 1

2. Aeronautic publications 12
3. Aircraft materials .. 28
4. Airframe construction 57
5. Sheet-metal working machines, tools, and procedures 85
6. Aircraft hardware 119
7. Aircraft damage repair 155
8. Airframe maintenance 210
9. Landing wheels , tires , and tubes 235
10. Tubing, flexible hose , and clamps 258
11. Corrosion control 284
12. Line operations and maintenance 333
Index 381
iii
READING LIST
USAFI TEXTS
United States Armed Forces Institute ( USAFI ) courses for additional

reading and study are available through your Educational Services Officer . *
The following courses are recommended :
C 151 General Mathematics I

C 152 General Mathematics II
D 700 General Aeronautics
E 275 General Science I
E 290 Physics I
* Members of the United States Armed Forces Reserve components , when

on active duty , are eligible to enroll for USAFI courses , services, and
materials if the orders calling them to active duty specify a period of 120
days or more , or if they have been on active duty for a period of 120 days or
more .
iv
CHAPTER 1
AVIATION STRUCTURAL MECHANICS RATING
This training manual is designed as a self not. Both Regular Navy and Naval Reserve
study text for use by those personnel of the personnel may hold general ratings.
Navy and Naval Reserve who are preparing to Service ratings identify subdivisions or
meet the professional ( technical) qualifications specialties within a general rating which require
for advancement to petty officer third class and related patterns of aptitudes and qualifications,
petty officer second class in the rating of and which provide paths of advancement for
Aviation Structural Mechanic S ( Structures ). career development . The general rating provides
Minimum professional qualifications for the primary means of identifying billet require
advancement are listed in the Manual of Quali ments and personnel qualifications; it is estab
fications for Advancement, NavPers 18068 lished or disestablished by the Secretary of the
( Series ). In preparing for the advancement Navy ; and it is provided a distinctive rating
examination , this manual should be studied in badge . The term " rate " identifies personnel
conjunction with Military Requirements for occupationally by pay grade . “ Rating” refers to
Petty Officer 3 & 2 , NavPers 10056 ( Series ) . The the occupational field . Service ratings can exist
latter covers the military requirements for all at any petty officer level , but they are most
third and second class petty officers, as well as common at the PO3 and PO2 levels . Both
detailed information on the Naval Aviation Regular Navy and Naval Reserve personnel may
Maintenance Program ( NAMP ) . hold service ratings .
The intent of this chapter is to provide
information on the enlisted rating structure , the
AMS rating, requirements and procedures for AVIATION STRUCTURAL MECHANIC
advancement, and references that will help you ( AM ) RATING
in performing your duties as an Aviation Struc
tural Mechanic S. This chapter also includes The AM rating is divided into three service
information on how to make the best use of ratings at paygrades E -4 through E-7 . The service
Rate Training Manuals . It is therefore strongly ratings are AME ( Safety Equipment ), AMS
recommended that you study this chapter care ( Structures) , and AMH ( Hydraulics) .
fully before beginning intensive study of the At paygrade E-8 the general rating , AM ,
remainder of the manual . applies. Therefore , upon advancement to E-8 .
paygrade E- 7 personnel ( AMEC's , AMSC's and
AMHC's ) are combined to become Senior
ENLISTED RATING STRUCTURE Aviation Structural Mechanics (AMCS ').
At paygrade E-9 the AM rating loses its
The present enlisted rating structure consists identity and personnel in the rating advance ,
of general ratings and service ratings . along with ADCS ' , to Master Chief Aircraft
General ratings identify broad occupational Maintenancemen ( AFCM's ) .
fields of related duties and functions. Some Figure 1-1 illustrates all paths of advancement
general ratings include service ratings; others do for an Airman Recruit to Master Chief Aircraft
1
AVIATION STRUCTURAL MECHANICS 3 & 2
LDO
AV.
MAINT .
WARRANT
OFFICER CWO CWO CWO
W -1 W- 2 W- 3 W- 4
AFCM
E-9
ADCS AMCS
E-8 E-8
ADJC ADRC AMSC

AMHC AMEC
E -7 E-7
ADJI ADRI АМНІ AMSI

ΑΜΕΙ
E-6 E-6
ADR2 AMS2
ADJ2 AMH2 AME2
E- 5 E -5
ADJ 3 ADR3 AMS3

AMH3 AME3
E -4 E-4
AIRMAN AME " A"

AMEAN
E- 3 SCHOOL
AIRMAN
APPRENTICE
E -2
LDO INPUT ZONE

*
AIRMAN SUCCESSFUL COMPLETION
RECRUIT OF CLASS A SCHOOL IS A
WARRANT OFFICER INPUT ZONE E- 1 MANDATORY REQUIREMENT
FOR ADVANCEMENT TO AME 3 .
AM . 1
Figure 1-1 . -Paths of advancement .
2
Chapter 1 -- AVIATION STRUCTURAL MECHANIC S RATING
Maintenanceman , Warrant Officer ( W-4) , or to LEADERSHIP

Limited Duty Officer. Shaded areas indicate
career stages where qualified personnel may One does not have to be a member of the
advance to Warrant Officer ( W- 1 ) and selected Armed Forces very long before he realizes that
Warrant Officers may advance to Limited Duty more leadership is required of the higher rates.
Officer. Personnel in enlisted rates and warrant Advancement not only entails the acquisition of
ranks not in a shaded area may advance only as superior knowledge, but also the demonstrated
indicated by the lines. ability to handle people . This ability increases in
The AMS maintains the fuselage , wings, importance as one advances through the petty
stabilizers , movable surfaces , landing wheels and officer rates.
tires, and the flight control systems. In perform In General Order No. 21 , the Secretary of the
ing these duties the AMS fabricates and as Navy outlined some of the most important
sembles various types of metallic and non aspects of naval leadership. By naval leadership
metallic parts, makes minor skin repairs and is meant the art of accomplishing the Navy's
structural repairs, replaces rivets and other types mission through people . It is the sum of those
of metal fasteners, performs tire and wheel qualities of intellect, of human understanding,
buildup , and paints aircraft . In performing these and of moral character that enable a man to
duties the AMS performs operational checks , inspire and to manage a group of people
locates troubles, removes and replaces mal successfully. Effective leadership therefore is
functioning components , and performs daily . based on personal example , good management
pretlight, postflight, and periodic inspections practices , and moral responsibility . The term
under the assigned AMS scope . leadership includes all three of these elements.
Duty assignments available to the AMS3 and The current Navy Leadership Program is
AMSZ are limited only by the location of designed to keep the spirit of General Order No.
operating aircraft. Billets exist on most carriers 21 ever before Navy personnel. If the threefold
from the smallest to the largest . AMS personnel objective is carried out effectively in every
assigned aboard carriers may be attached either command, the program will make better leaders
to the ship or to one of the embarked squad of men in their present and future assignments.
rons. Regardless of how assigned, the AMS As one advances up the leadership ladder , more
will be working with other maintenance person and more of his worth to the Navy will be
nel assisting in keeping the aircraft flying. judged on the basis of the amount of efficient
AMS personnel play an equally important role work obtained from his subordinates rather than
in patrol squadrons, which constitute a portion how much of the actual work is performed by
himself.
of the nation's antisubmarine warfare protec
tion . By hard work and initiative , the AMS may For further information on the practical
become qualified as an aircrewman in patrol application of leadership and supervision , the
type aircraft. latest edition of Military Requirements for Petty
Many interesting overseas shore billets exist Officer 3 & 2. NavPers 10056-C , should be
for AMS's . If married , some third class and all studied . The principles and problems of naval
second class petty officers may qualify to bring leadership covered in NavPers 15924 ( Series)
their dependents to these overseas locations at and the Leadership Checklist for Petty Officers,
government expense . Shorter duty tours usually NavPers 2932-3 , will be useful tools in develop
prevail at the few overseas stations where ing sound leadership traits .
dependents are not allowed or choose not to go .
Between sea tours, the AMS Third of Second
Class may be assigned to one of the many naval ADVANCEMENT
air stations along the Gulf, East Coast , and West
Coast . In addition , the Naval Training Command Some of the rewards of advancement are easy
has a few naval air stations located inland, from to see . You get more pay . Your job assignments
which aircraft are operated and AMS's may be become more interesting and more challenging.
assigned . You are regarded with greater respect by officers
3
AVIATION STRUCTURAL MECHANIC S 3 & 2
and enlisted personnel. You enjoy the satisfac 1-2 gives a more detailed view of the require
tion of getting ahead in your chosen Navy ments for advancement of active duty personnel;
career . figure 1-3 gives this information for inactive
The advantages of advancement are not yours duty personnel.
alone. The Navy also profits . Highly trained Remember that the requirements for advance
personnel are essential to the functioning of the ment can change . Check with your educational
Navy . By advancement, you increase your value services office to be sure that you know the
to the Navy in two ways : First , you become most recent requirements.
more valuable as a technical specialist in your Advancement is not automatic . After you
own rating; and second , you become more have met all the requirements , you are eligible
valuable as a person who can train others and for advancement. You will actually be advanced
thus make far-reaching contributions to the only if you meet all the requirements ( including
entire Navy . making a high enough score on the written
examination ) and if quotas permit.
HOW TO QUALIFY
FOR ADVANCEMENT HOW TO PREPARE
FOR ADVANCEMENT
What must you do to qualify for advance
ment ? The requirements may change from time What must you do to prepare for advance
to time, but usually you must: ment ? You must study the qualifications for
advancement, work on the personal qualification
1. Have a certain amount of time in your standard and practical factors, study the
present grade . required Rate Training Manuals , and study other
2. Complete the required Rate Training material that is required . You will need to be
Manuals by either demonstrating a knowledge of familiar with the following:
the material in the manual by passing a locally
prepared and administered test , or by passing 1. Manual of Qualifications for Advance
the Enlisted Correspondence Course based on ment, NavPers 18068 ( Series ) .
the Rate Training Manual and the appropriate 2. Personnel Qualification Standard for the
military requirements manual. equipment /system and rating assigned .
3. Utilizing an appropriate Personnel 3. Record of Practical Factors. Nav Pers
Qualification Standard (when applicable ) as a 1414/1 .
guideline, become qualified and demonstrate 4. Bibliography for Advancement Study,
your ability to perform all the practical require Nav Tra 10052 ( Series ).
ments for advancement by completing the 5. Applicable Rate Training Manuals and
Record of Practical Factors , NavPers 1414/1 . their companion Enlisted Correspondence
4. Be recommended by your commanding Courses.
officer , after the petty officers and officers 6. Examinations for advancement.
supervising your work have indicated that they
consider you capable of performing the duties of Collectively , these documents make up an
the next higher rate . integrated training package tied together by the
5. Successfully complete the applicable qualifications. The following paragraphs describe
military / leadership examination which is these materials and give some information on
required prior to participating in the advance how each one is related to the others.
ment ( professional) examination .
" Quals " Manual
Some of these general requirements may be
modified in certain ways . One of these ways is The Manual of Qualifications for Advance
through the accelerated advancement program ment ,NavPers 18068 ( Series ), gives the
( BuPers Note 1430 of 22 Sept. 1970 ) . Figure minimum requirements for advancement. This
4
Chapter 1 - AVIATION STRUCTURAL MECHANIC S RATING
#1 E3 # E4 + E5 + E6 + E7 + E8
REQUIREMENTS * El to E2 E2 to E3 to FA to E5 to E6 to E7 to E8 to E9
4 mos . 36 mos .
service as E - 6 .
Or 8 mos. 6 mos. 12 mos. 24 mos. 8 years
SERVICE comple total 36 mos 24 mos.
tion of as E-2 . as E -3 as E -4 as E-5 .
enlisted as E.1 . as E-8 .
service . 8 of 11 10 of 13
years years
Recruit Class A total total
Training for PR3
DT3.PT3
Class B l service service
( c.o. for AGC must be must be
may ad AME 3 .
SCHOOL vance up HM 3 . MUC. enlisted. enlisted .
to 10 % PN 3. MNC . It
of grad FTB 3 .
uating MT 3 .
class . )
Locally
PRACTICAL prepared Record of Practical factors , Naypers 1414/1 , must be 1
FACTORS check completed for E-3 and all PO advancements .

offs .
Specified ratings must complete

PERFORMANCE applicable performance tests be
TEST
fore taking examinations .
ENLISTED As used by CO
Counts toward performance factor credit in ad .
PERFORMANCE when approving
EVALUATION advancement . vancement multiple .
Locally See
**
EXAMINATIONS | prepared Navy-wide examinations required Navy -wide,
below . for all PO advancements. selection board .
tests .
Required for 3-3 and all PO advancements Correspondence

RATE TRAINING unless waived because of school comple : courses and
MANUAL (INCLUD recommended
ING MILITARY tion , but need not be repeated if identical
1
course has already been completed . See reading . See

REQUIREMENTS ) NayPers 10052
Navpers 10052 ( current edition ).
( current edition ) .
AUTHORIZATION Commanding
Officer Naval Examining Center
* All advancements require commanding officer's recommendation .
t 1 year obligated service required for E-5 and E -6; 2 years for E-1, E-8 and E - 9.
# Military leadership exam required for E-4 and E-5.
** For E -2 to E -3 , NAVEXAMCEN exams or locally prepared tests may be used .
tt Waived for qualified EOD personnel.
Figure 1-2.-Active duty advancement requirements.
5
* El to E263to E3E4to E4to E5 to E6 to

REQUIREMENTS E8 E9
12 E5 E6 E7
36 mos . 36 mos. 24 mos .

TOTAL TIME with with with
4 mos. 6 mos . 6 mos. 12 mos. 24 mos. total total total
IN GRADE
8 yrs 11 yrs 13 yrs
service service service
TOTAL TRAINING
DUTY IN GRADE 14 days 14 days 14 days 14 days 28 days 42 days 12 days 28 days
PERFORMANCE Specified ratings must complete applicable

TESTS performance tests before taking examination.
DRILL Satisfactory participation as a member of a drill unit

PARTICIPATION in accordance with BUPERSINST 5400.42 series .
PRACTICAL FACTORS
( INCLUDING MILITARY Record of Practical factors , Navpers 1414/1 , must be completed
for all advancements .
REQUIREMENTS )
RATE TRAINING
MANUAL ( INCLUDING Completion of applicable course or courses must be entered
MILITARY REQUIRE in service record.
MENTS )
Standard Exam
required for all PO
Advancements. Standard Exam ,
EXAMINATION Standard Exam Also pass Selection Board.
Military Leadership Exam
far E-4 and E -5.
Commanding
AUTHORIZATION Officer Naval Examining Center
* Recommendation by commanding officer required for all advancements.

† Active duty periods may be substituted for training duty.
Figure 1-3 . - Inactive duty advancement requirements.
6
manual is usually called the " Quals ” Manual, Personnel Qualification Standards
and the qualifications themselves are often
called " quals ". The qualifications are of two Personnel Qualification Standards ( PQS )
general types : military requirements, and profes (OpNav Instruction 3500.34 ) are presently being
sional ( or technical) qualifications. utilized to provide guidelines in preparing for
Military requirements apply to all ratings advancement and qualification to operate
rather than to any one particular rating . Military specific equipment and systems . They are
requirements for advancement to third class and designed to support the advancement require
second class petty officer rates deal with mili ments as stated in the " Quals " Manual.
tary conduct , naval organization , military The “ Quals " and Record of Practical Factors
justice, security , watch standing, and other are stated in broad terms. Each PQS is much
subjects which are required of petty officers in more specific in its questions that lead to
all other ratings . qualification. It provides an analysis of specific
Professional qualifications are technical or equipment and duties , assignments, or respon
professional requirements that are directly sibilities which an individual or group of individ
related to the work of each rating. uals ( withinin the same rating ) may be called
Both the military requirements and the upon to carry out. In other words, each POS
professional qualifications are divided into provides an analysis of the complete knowledge
subject matter groups; then , within each subject and skills required of that rating tied to a
matter group , they are divided into practical specific weapon system ( aircraft and /or individ
factors and knowledge factors. Practical factors ual systems or components ).
are things you must be able to DO. Knowledge Each qualification standard has four main
factors are things you must KNOW in order to subdivisions in addition to an introduction and a
perform the duties of your rate . glossary of PQS terms . They are as follows:
The qualifications for advancement and a
bibliography of study materials are available in 100 Series Theory
your educational services office . Study these 200 Series Systems
qualifications and the military requirements 300 Series Watchstations ( duties , assign
carefully . The written examination for advance ments, or responsibilities ).
ment will contain questions relating to the 400 Series -- Qualifications cards
knowledge factors and the knowledge aspects of
the practical factors of both the military require The introduction explains the complete use of
ments and the professional qualifications. If you the qualification standard in terms of what it
are working for advancement to second class, will mean to the user as well as how to use it .
remember that you may be examined on third The Theory ( 100 Series ) section specifies the
class qualifications as well as on second class theory background required as a prerequisite to
qualifications. the commencement of study in the specific
It is essential that the “ quals ” reflect current equipment or system for which the POS was
requirements of fleet and shore operations , and written . These fundamentals are normally taught
that new fleetwide technical , operational, and in the formal schools ( Preparatory , Funda
procedural developments be included . For these mentals, and Class A ) phase of an individual's
reasons, the qualifications are continually under training. However, if the individual has not been
evaluation . Although there is an established to school , the requirements are outlined and
schedule for revisions to the “ quals” for each referenced to provide guidelines for a self -study
rating , urgent changes to the " quals" may be program
made at any time . These revisions are issued in The Systems ( 200 Series) section breaks down
the form of changes to the " Quals" Manual. the equipment or systems being studied into
Therefore, never trust any set of “ quals” until functional sections . PQS items are essentially
you have checked the change number against an questions asked in clear, concise statement
up -to -date copy of the " Quals " Manual. Be sure ( question ) form and arranged in a standard
you have the latest revision . format. The answers to the questions must be
7
extracted from the various maintenance manuals division officer, and maintenance officer as
covering the equipment or systems for which the required to certify proper qualification. The
PQS was written. This section asks the user to completion of part or all of the POS provides a
explain the function of the system , to draw a basis for the supervising petty officer and officer
simplified version of the system from memory , to certify completion of Practical Factors for
and to use this drawn schematic or the Advancement .
schematic provided in the maintenance manual
while studying the system or equipment .
Emphasis is given to such areas as maintenance Record of Practical Factors
management procedures , components ,
component parts, principles of operation, sys Before you can take the Navy-wide examina
tem interrelations , numerical values considered tion for advancement , there must be an entry in
necessary to operation and maintenance, and your service record to show that you have
safety precautions . qualified in the practical factors of both the
The Watchstation ( 300 series) section includes military requirements and the professional quali
questions regarding the procedures the individ fications. A special form known as the Record
ual must know to operate and maintain the of Practical Factors , NavPers 1414/1 (plus the
equipment or system . A study of the items in abbreviation of the appropraite rating ), is used
the 200 series section provides the individual to keep a record of your practical factor
with the required information concerning what qualifications. The form lists all practical
the system or equipment does , how it does it , factors, both military and professional. As you
and other pertinent aspects of operation . In the demonstrate your ability to perform each
300 series section , the questions advance the practical factor , appropriate entries are made in
qualification process by requiring answers or the DATE and INITIALS columns .
demonstrations of ability to put this knowledge Changes are made periodically to the Manual
to use or to cope with maintenance of the of Qualifications for Advancement and revised
system or equipment . Areas covered include forms of NavPers 1414/1 are provided when
normal operation ; abnormal or emergency necessary . Extra space is allowed on the Record
operation ; emergency procedures which could of Practical Factors for entering additional
limit damage and/or casualties associated with a practical factors as they are published in
particular operation ; operations that occur too changes . The Record of Practical factors also
infrequently to be considered mandatory provides space for recording demonstrated
performance items ; and maintenance proce proficiency in skills which are within the general
dures/ instructions such as checks , tests , repair, scope of the rate but which are not identified as
replacement , etc. minimum qualifications for advancement .
The 400 series section consists of the quali If you are transferred before you qualify in
fication cards. These cards are the accounting all practical factors, NavPers 1414/1 should be
documents utilized to record the individual's forwarded with your service record to your next
satisfactory completion of items necessary for duty station . You can save yourself a lot of
becoming qualified in duties assigned . Where the trouble by making sure that this form is actually
individual starts in completing a standard will inserted in your service record before you are
depend on his assignment within an activity . The transferred . If the form is not in your service
complete PQS is given to the individual being record , you will be required to start all over
qualified so that he can utilize it at every again and requalify in the practical factors which
opportunity to become fully qualified in all have already been checked off.
areas of his rating and the equipment or system A second copy of the Record of Practical
for which the PQS was written . Upon transfer to Factors should be made available to each man in
a different activity, each individual must re pay grades E-2 through E-8 for his personal
qualify . The answers to the questions asked in record and guidance.
the qualification standards may be given orally The importance of NavPers 1414/1 cannot be
or in writing to the supervisor, the branch or overemphasized . It serves as a record to indicate
8
Chapter 1 -AVIATION STRUCTURAL MECHANICS RATING
to the petty officers and officers supervising the material that is listed for third class. If you
your work that you have demonstrated are working for advancement to second class,
proficiency in the performance of the indicated study the material that is listed for second class.
practical factors and is part of the criteria Remember that you are also responsible for the
utilized by your commanding officer when he references listed at the third class level .
considers recommending you for advancement . In using NavTra 10052 , you will notice that
In addition , the proficient demonstration of the some Rate Training Manuals are marked with an
applicable practical factors listed on this form asterisk ( * ). Any manual marked in this way is
can aid you in preparing for the examination for MANDATORY - that is , it must be completed at
advancement. Remember that the knowledge the indicated rate level before you are eligible to
aspects of the practical factors are covered in the take the Navy-wide examination for advance
examinations for advancement . Certain knowl ment. Each mandatory manual may be
edge is required to demonstrate these practical completed by passing the appropriate enlisted
factors and additional knowledge can be correspondence course that is based on the
acquired during the demonstration . Knowledge mandatory training manual ; passing locally
factors pertain to that knowledge which is prepared tests based on the information given in
required to perform a certain job . In other the training manual, or in some cases , success
words , the knowledge factors required for a fully completing an appropriate Class A School .
certain rating depend upon the jobs ( practical Do not overlook the section of NavTra 10052
factors ) that must be performed by personnel of which lists the required and recommended refer
that rating. Therefore , the knowledge required ences relating to the military standards/
to proficiently demonstrate these practical requirements for advancement. For example , all
factors will definitely aid you in preparing for personnel must complete the Rate Training
the examination for advancement. Manual, Military Requirements for Petty Officer
3 & 2 , NavPers 10056 ( Series ) , for the ap
Nav Tra 10052 propriate rate level before they can be eligible to
advance .
The references in NavTra 10052 which are
Bibliography for Advancement Study , NavTra
10052 ( Series ) , is a very important publication recommended , but not mandatory , should also
for anyone preparing for advancement . This be studied carefully . All references listed in
bibliography lists required and recommended NavTra 10052 may be used as source material
for the written examinations at the appropriate
Rate Training Manuals and other reference
rate levels .
material to be used by personnel working for
advancement. NavTra 10052 is revised and
issued once each year by the Naval Training Rate Training Manuals
Command . Each revised edition is identified by
a letter following the NavTra number. When There are two general types of Rate Training
using this publication , be sure that you have the Manuals . Rating manuals (such as this one) are
most recent edition . prepared for most en listed rates, giving informa
If extensive changes in qualifications occur tion that is directly related to the professional
between the annual revisions of NavTra 10052 , a qualifications. Basic manuals give information
supplementary list of study material may be that applies to more than one rate and rating.
issued in the form of a Notice . When you are Basic Electricity , NavPers 10086 ( Series ) , is an
preparing for advancement , check to see example of a basic manual , because many ratings
>
whether changes have been made in the quali use it for reference .
fications. If changes have been made , see if a Rate Training Manuals are produced by field
BuPers Notice has been issued to supplement activities under the management control of the
NavTra 10052 . Naval Training Command . Manuals are revised
The required and recommended references are from time to time to keep them up to date
listed by rate level in Nav Tra 10052. If you are technically . The numbering system is being
working for advancement to third class, study changed from NavPers to Nav Tra. The revision
9
of a Rate Training Manual is identified by a in the details by intensive study . In each study
letter following the NavPers or NavTra number. period , try to cover a complete unit - it may be a
You can tell whether any particular copy of a chapter, a section of a chapter, or a subsection .
Rate Training Manual is the latest edition by If you know the subject well , or if the material
checking the number in the most recent edition is easy , you can cover quite a lot at one time .
of List of Training Manuals and Correspondence Difficult or unfamiliar material will require more
Courses, NavTra 10061 ( Series ) . NavTra 10061 study time.
is actually a catalog that lists training manuals
and correspondence courses ; you will find this 6. In studying any one unit -- chapter, section ,
catalog useful in planning your study program . or subsection - write down the questions that
Rate Training Manuals are designed to help occur to you . Many people find it helpful to
you prepare for advancement. The following make a written outline of the unit as they study,
suggestions may help you to make the best use or at least to write down the most important
ideas .
of this manual and other Navy training publica
tions when you are preparing for advancement. 7. As you study, relate the information in the
training manual to the knowledge you already
have . When you read about a process, a skill , or
1. Study the military requirements and the a situation , try to see how this information ties
professional qualifications for your rate before in with your own past experience.
you study the training manual, and refer to the 8. When you have finished studying a unit ,
“ quals ” frequently as you study. Remember, take time out to see what you have learned .
you are studying the training manual in order to
Look back over your notes and questions.
meet these “ quals .' Maybe some of your questions have been
2. Set up a regular study plan. If possible , answered , but perhaps you still have some that
schedule your studying for a time of day when are not answered . Without referring to the
you will not have too many interruptions or training manual, write down the main ideas that
distractions. you have learned from studying this unit. Do
3. Before you begin to study any part of the not quote the manual. If you cannot give these
ideas in your own words , the chances are that
training manual intensively , become familiar you have not really mastered the information .
with the entire manual . Read the preface and
the table of contents. Check through the index . 9. Use Enlisted Correspondence Courses
Look at the appendixes . Thumb through the whenever you can . The correspondence courses
manual without any particular plan , looking at are based on Rate Training Manuals or on other
the illustrations and reading bits here and there appropriate texts . As mentioned before ,
as you see things that interest you . completion of a mandatory Rate Training
4. Look at the training manual in more Manual can be accomplished by passing an
detail , to see how it is organized. Look at the Enlisted Correspondence Course based on the
table of contents again . Then , chapter by Rate Training Manual. You will probably find it
chapter , read the introduction, the headings , and helpful to take other correspondence courses, as
the subheadings. This will give you a clear well as those based on mandatory training
picture of the scope and content of the manual. manuals. Taking a correspondence course helps
As you look through the manual in this way , ask you to master the information given in the
yourself some questions: What do I need to training manual, and also helps you see how
learn about this? What do I already know about much you have learned .
this ? How is this information related to in
10. Think of your future as you study Rate
formation given in other chapters? How is this Training Manuals. You are working for advance
information related to the qualifications for ment to third class or second class right now ,
advancement ? but someday you will be working toward higher
5. When you have a general idea of what is in rates. Anything extra that you can learn now
the training manual and how it is organized , fill will help you .
10
SOURCES OF INFORMATION handtool operations that are performed by

enlisted men of all ratings in their day -to -day
One of the most useful things you can learn work . The manual is plentifully supplied with
about a subject is how to find out more about it . illustrations showing, as well as telling, how to
No single publication can give you all the perform specific operations. Many of the jobs
information you need to perform the duties of performed by the AMS are included , making it a
your rating. You should learn where to look for valuable reference not only in performing your
accurate , authoritative, up-to -date information daily duties but also in studying for advance
on all subjects related to the military require ment.
ments for advancement and the professional It is essential that AMS's have a thorough
qualifications of your rating. understanding of basic machines. Basic
Some of the publications described in this. Machines, NavPers 10624 , contains an excellent
chapter are subject to change or revision from presentation on basic machines. Beginning with
time to time - some at regular intervals , others as the simplest of machines-- the lever --the manual
the need arises. When using any publication that proceeds with the discussion of block and
is subject to change or revision , be sure that you tackle , wheel and axle , inclined plane, screw ,
have the latest edition . When using any publica and gears. It explains the concepts of work and
tion that is kept current by means of changes, be power , and differentiates between the terms
sure you have a copy in which all official " force " and " pressure .” The fundamentals of
changes have been made. Studying canceled or hydrostatic and hydraulic mechanisms are dis
obsolete information will not help you to do cussed in detail. The final chapter includes
your work or to advance in rating ; it is likely to several examples of the combination of simple
be a waste of time, and may even be seriously mechanisms to make complex machines.
misleading. A thorough understanding of the material
Several publications that you will need to presented in Basic Machines will greatly
study or refer to as you prepare for advance facilitate an understanding of the machines with
ment have already been discussed earlier in this which the AMS works, many of which are a
chapter. In addition , you may find it useful to combination of a number of simple machines.
consult some of the Rate Training Manuals Additional publications that you may find
prepared for other Group IX (Aviation ) ratings. useful are as follows :
Reference to these training manuals will add to
your knowledge of the duties of other men in
the field of aviation. Also , you may find it Blueprint Reading and Sketching, NavPers
useful to consult the Basic Rate Training 10077 ( Series ) .
Manuals described in the following paragraphs. Basic Electricity , NavPers 10086 ( Series)
Tools and Their Uses , NavPers 10085 ( Series) , ( chapters 1,3 ) .
contains descriptions of a number of basic Fluid Power, NavPers 16193 ( Series ) .
11
CHAPTER 2
AERONAUTIC PUBLICATIONS
Aeronautic publications are issued by au specific purpose . They are identified as follows :
thority of the Commander of the Naval Air Weapons /Stores, Conventional/
Airborne Weapons/Stores,
Systems Command . These publications are the Nuclear , Checklists/Stores Reliability Cards/
sources of information for guiding naval person Manual, NavAir 01-700 . This part of the publica
nel in the operation and maintenance of all tions index is not used by AMS personnel and
aircraft and related equipment within the Naval therefore is given no further coverage in this
Establishment. By proper use of these publica chapter.
tions, all aircraft and other aeronautic equip Navy Stock List of Forms and Publications,
ment can be operated and maintained efficiently NavSup Publication 2002 ; Section VIII , Parts C
and uniformly throughout the Navy . and D, Numerical Sequence List ( also referred to
Aeronautic publications may be grouped into as Numerical Index ).
two major classes or groups-- those issued in the Equipment Applicability List ( Volumes 1
form of MANUALS , and those issued in the through 7 ) , NavAir 00-500A .
form of LETTER MATERIAL. Aircraft Application List , NavAir 00-500B .
When a new aircraft, engine, accessory , or Directives Application List , NavAir 00-500C .
other item of equipment is accepted by the Letter Type Technical Directives Equipment
Navy , manuals necessary to insure its proper and Subject Application List , NavAir 00-500D .
operation and upkeep are prepared and issued to A description of these lists and their uses is
all activities using and /or maintaining the equip presented in the following paragraphs .
ment. Supplemental information and other
directive type publications that must be issued NUMERICAL SEQUENCE LIST
from time to time are issued in the form of
letter material. Both manual and letter publica NavSup Publication 2002 is a 13 -section
tions may, on occasion , be properly referred to index of all the forms and publications used
as directives . Broadly speaking, any communica throughout the Navy and stocked by the Naval
tion which initiates or governs action , conduct, Supply Systems Command. Section VIII of this
or procedure is a directive . Stock List contains Naval Air Systems Com
All aeronautic publications, both manual and mand ( NavAirSysCom ) publications. This sec
letter type , are assigned a title and code number. tion is made up of four parts - A , B , C , and D.
When they are available for issue , all publica Parts A and B pertain to ordnance publica
tions , except Instructions and Notices , are listed tions. Part C is the numerical listing of manual
in the Naval Aeronautic Publications Index . type aeronautic technical publications , and Part
D is the numerical listing of letter type publica
tions . These two , Parts C and D , are referred to
NAVAL AERONAUTIC PUBLICATIONS as the Numerical Sequence List or Numerical
INDEX Index of the Naval Aeronautic Publications
Index .
The Naval Aeronautic Publications Index is Part C (manual publications) contains its table
made up of six parts , each of which serves a of contents , as well as the instructions for using
12
Chapter 2 - AERONAUTIC PUBLICATIONS
both Parts C and D of NavSup Publication 2002 . restrictions concerning the requisitioning of the
Included in these instructions are the method publication . In addition , the date of the latest
for procuring aeronautic publications, the forms issue or revision of the publication is listed . This
and procedures required for ordering publica provides a means whereby the issue and /or
tions, and explanations of certain codes used in revision dates of the publications on hand in an
the Index . Also a listing of canceled publications activity can be checked against the dates listed
for Part C is contained in the last pages of Part in the current issue and supplement ( discussed
C. later) of the Numerical Index , thus assuring that
Part C is divided into subject matter groups. the publications are current.
and all publications within a group are then
listed in numerical order. For example , all EQUIPMENT APPLICABILITY LIST
manuals in the 00 series are listed first, then
followed by the 01 , 02 , 03 , etc. , through the 51 Basically, the Equipment Applicability List ,
series . The listing includes the publication code NavAir 00-500A , is a cross-reference index
number, stock number , title , date of latest issue
listing of Naval Air Systems Command (NavAir
or revision , security classification, requisition SysCom ) publications of aircraft components
restriction code , and basic or change code . A
listing of the general subject groups is shown in Table 2-1 . -General subject classification
table 2-1 .
Part D ( letter type directives) contains a table numbers for manual type publications.
of contents , general alphabetical cross
а
00
General
reference listing, and a listing of Air Force-Navy Aircraft 01
code cross-references .
Powerplants 02
Part D is divided into a number of sub
( 02A Reciprocating engines, 02B Jet en
sections. Included among those of interest to the
AMS are general , aircraft , accessories , and gines, 02F Rocket engines)
Accessories 03
support equipment. Listed in the general section 04
Hardware and Rubber Material
are Aircrew System Bulletins and Changes, Instruments 05
Aviation Clothing and Survival Equipment Fuels , Lubricants, and Gases 06
Bulletins and Changes, Technical Orders , and Dopes and Paints 07
Technical Notes . In the aircraft section are listed 08 & 16
Electronics
all Aircraft Changes and Bulletins. The acces Instructional Equipment and Training
sories section contains a listing of all Accessories Aids 09 & 28
Changes and Bulletins . The support equipment Photography 10
section contains a listing of all Support Equip Aviation Armament 11
ment Changes and Bulletins. 12
The Numerical Indexbe used to
must Fuel and Oil Handling Equipment
Parachute and Personal Survival Equipment 13
completely identify and , therefore , to order 14
Hangars and Flying Field Equipment
required publications . However, the other parts
of the Index ( discussed in the following para Standard Preservation and Packaging Instruc
tions 15
graphs ) must be used to determine what publica
tions are available for a specific item of equip Machinery, Tools , and Test Equipment 17 & 18
ment and to check the applicability of publica Ground Servicing and Automotive Equip
ment 19
tions to specific equipment.
When an applicable publication number is Descriptive Data Sheets for Aviation Sup
port Equipment .. 20
found in one of the other parts of the Naval ed
Aeronautic Publications Index , it can be easily ( Being supersed by Ground Support
Equipment Illustrations (GSEI ) )
located in the Numerical Index . Here , it can be 24 & 39
Chemical Equipment
more completely identified as to title and 50
nomenclature , stock number ( for manual type Meteorology
Ship Installations 51
publications ) , security classification, and any
13
and related equipment according to model , type , DIRECTIVES APPLICATION LIST

or part number. BY AIRCRAFT CONFIGURATION
Since this index contains several thousand
entries, one volume would be very cumbersome The Directives Application List by Aircraft
to use . For this reason , this index is divided into Configuration , NavAir 00-500C , contains a list
several volumes. At the time of this writing, ing of the active Naval Air Systems Command
there are seven volumes. letter ty pe technical directives with respect to
With the exception of several small sections in their applicability to aircraft. The lists in this
the first part of Volume 1 , the Equipment volume are arranged first by aircraft series ,
Applicability List is one continuous index of second by aircraft configuration , and third by
model , type, or part numbers in alphanumerical Airframe/Aircraft Bulletin and/or Change
sequence . numbers. NOTE : Configuration refers to
In addition to an Introduction , which modifications made to a basic aircraft model.
explains the headings at the top of each page , For instance , A -4A , A -4B , TA4F , etc. , are all
the other sections in the first part of Volume 1 different configurations of the A-4 aircraft
pertain primarily to manuals for aircraft, model.
weapons systems, and aircraft engines. There
fore, the publication numbers are listed accord EQUIPMENT AND SUBJECT
ing to aircraft , aircraft engine , and weapons APPLICABILITY LIST
system designation.
The Equipment Applicability List should be The Equipment and Subject Applicability
used when attempting to determine what List , NavAir 00-500D . is a relatively recent
publications are available on a particular item of addition to the Naval Aeronautic Publications
equipment, and the manufacturer and part Index . It contains a cross -reference index listing
number of the item are known . of Naval Air Systems Command letter type
technical directives . It serves the same purpose
AIRCRAFT APPLICATION LIST for letter type technical directives as the Equip
ment Applicability List , NavAir 00-500A , does
The Aircraft Application List , NavAir for technical manuals. However, since the
00-500B , contains a listing of all manuals NavAir 00-500D lists only those model/ type
grouped according to their application to an part numbers for which technical directives have
aircraft. This part of the index does not contain been issued , it is much smaller than the NavAir
listings of any letter type publications, and all 00-500A . The complete List is contained in one
manuals are listed by publication code number volume but is divided into two parts. Part A is
only . the Equipment Index and Part B is the Subject
A list of basic numbering categories is Index .
provided in the front of the book . This list may Part A contains a listing of all Naval Air
be used in determining the general type of Systems Command letter type technical
equipment covered in a publication. For deter directives on aircraft components and related
mining the specific item of equipment covered equipment by model/ type part number . Each
by a publication and the title of the publication, number is listed in alphanumerical sequence
reference should be made to Part C of Section within its cognizant equipment series . At the
VIII in NavSup Publication 2002 . present time, Part A is divided into nine series .
The Aircraft Application List is especially The Accessories , Aircrew Systems, and Clothing
handy for determining what manuals are avail and Survival Equipment Series are of most
able for a particular model of aircraft. Included interest to AM personnel.
under each model is a complete listing of Part B of Nav Air 00-500D contains aa listing of
applicable manuals. This listing includes all active Naval Air Systems Command letter type
allowance lists, aircraft manuals, engine manuals, directives by subject. This part of the List
accessories manuals, etc. , pertaining to that pertains primarily to Airframe Bulletins and
particular model of aircraft . Changes .
14
UPDATING THE INDEX and filed . A knowledge of the numbering sys

tems used will enable the AMS to locate any
Each List in the Naval Aeronautic Publica desired information with a minimum of effort.
tions Index is updated at regular intervals by the A brief explanation of the coding of manuals
issuance of a new list . In addition , some of these listed in the index is given in the following
Lists are kept current by the periodic issuance of sections. Coding for letter type material is
supplements between issues of the Basic List . covered later in this chapter.
The dates and intervals of the issuance of new Code numbers assigned to manuals consist of
Lists and supplements have changed from time a prefix and a series of three parts . The prefix
to time in the past . consists of letters which identify the originator
At the time of this writing , the Numerical of the publication .
Index ( Parts C and D of NavSup Publication NavAir is the prefix assigned to technical
2002 ) is issued annually in September. Sup publications originated by the Naval Air Systems
plements are issued bimonthly between each Command. In the stock list , it is shortened to
basic issue. The Equipment Applicability List , NA .
NavAir 00-500A , is issued annually in The three parts which make up the remaining
November. This List is kept current by the portions of the number indicate the following:
issuance of quarterly supplements between each
basic issue . The Aircraft Application List , Part I is a two-digit number that indicates the
NavAir 00-500B, is issued in March and general subject classification of the equipment
September, and the Directives Application List covered by the publication. Table 2-1 lists the
by Aircraft Configuration , NavAir 00-500C , is general subject categories and the appropriate
issued in January and July of each year . Sup two -digit numbers.
plements are not issued for these Lists.
Part II of the publications code number
The Equipment and Subject Application List , consists of numbers and/or numbers and letters
NavAir 00-500D , is issued in May and November and indicates the specific class , group , type , or
of each year , and as of this writing, supplements model and manufacturer of the equipment. The
will be issued as the information is developed . subject breakdowns are listed at the beginning of
Supplements list all aeronautic publications each separate major division within the
distributed during the previous period , and those Numerical Index .
publications that have been superseded ,, Part III consists of a number or numbers
canceled, or revised . Supplements are cumula which designate a specific manual. For aircraft
tive , that is , all material from the preceding and powerplants, this number designates a
supplement is incorporated in the latest sup specific type of manual. For other types of
plement; therefore , at any given time, not more equipment, this part is assigned in numerical
than one supplement is in effect for any List . sequence and has no reference to the type of
Naturally , the reissue of a basic List cancels the manual.
outstanding supplement.
Supplements for the Numerical Index ( Parts Figure 2-1 illustrates the identification and
and D of Section VIII of NavSup Publications decoding of a complete manual publication
2002 ) are identified by the word " supplement" number.
printed near the upper right-hand corner of the
cover . Supplements to the NavAir 00-500 A
SECURITY OF CLASSIFIED
Series publications are identified by the word PUBLICATIONS
“ supplement" printed in the middle of the cover
page .
The Department of the Navy Supplement to
the DOD Information Security Program Regula
PUBLICATIONS NUMBERING SYSTEM tions ( OpNav Instruction 5510.1 Series ) , issued
by the Chief of Naval Operations, is the basic
Code numbers are assigned to all publications security directive relating to safeguarding
in order that they may be identified , indexed , classified information . Its provisions apply to all
15
Prefix Part I Part II Part III
工业 r
NA 85 ADA 2 2
A NavAirSysCom originated publication

pertaining to an aircraft
built by Grumman Aircraft Engineering Corporation
The particular model is the A -6A ,
the publication is a Maintenance Instructions Manual ,
and this entire code number identifies a particular volume
of the Maintenance Instructions Manual.
AM . 224
Figure 2-1 . -Identification and decoding of manual publication code number.
military and civilian personnel and to all activi delivery of urgently required technical informa
ties of the Naval Establishment. tion . Under this system , information affecting
The manual contains detailed instructions for flight safety, hazards to personnel , or grounding
classifying, marking, and handling classified in of aircraft is disseminated via naval message and
formation , and for access to and authorized immediately incorporated into the affected
disclosure of the information . manual. A manual change page followup is then
The AMS , from time to time, has occasion to required within 15 days of the release of the
use classified publications relating to the per message . Information of a less urgent nature is
formance of his work . Before he accepts such disseminated by RAC change pages that must be
publications he must be cleared to the ap printed within 30 days after problem resolution
propriate degree to handle this classified matter. and is generally limited to 12 pages or less .
It is then mandatory that he have knowledge of The RAC System for manual changes replaces
and abide by the instructions in the Security the previous Interim Manual Change System but
Manual pertaining to handling classified mate does not affect the normal manual change and
rial . revision requirements. It merely supplements the
Publications listed in the Numerical Index existing Normal Change System to provide for
( Parts C and D of Section VIII of NavSup rapid issue of urgently required data which
Publication 2002 ) are unclassified unless other previously was not available to the user for long
wise marked " 1" ( confidential) or " 4 " ( secret) periods of time due to system red tape , such as
in the column headed PS (physical security ). routing and printing delays .
The Index is not classification authority . The As shown in table 2-1 , manuals are published
supplements to the Index contain information in a number of different general subject cate
of classification action on a "when -occurring " gories . Those of special interest to the AMS3
basis . and AMS2 are the General Manuals ( 00 series),
Aircraft Manuals ( 01 series) , and the Accessories
Manuals (03 series ). Certain manuals in other
MANUAL TYPE PUBLICATIONS series may be used occasionally , but those listed
here are of special importance to the Aviation
Structural Mechanic .
To attain a satisfactory state of readiness,
technical manuals are developed , published, and
distributed concurrently with the weapon sys GENERAL MANUALS ( 00 SERIES )
tem or equipment that they cover. Periodic
changes and revisions are issued as necessary to As indicated by the title , this series of
insure that manuals continually reflect equip manuals includes information of interest to all
ment changes and current operational and naval aviation personnel. Included are four parts
support concepts and procedures . of the Naval Aeronautic Publications Index
The Rapid Action Change (RAC) System ( 00-500A , 00-500B , 00-500C , and 00-500D ,
provides a quick response capability for the already described ) , NavAir Outfitting Lists and
16
Chapter 2 -AERONAUTIC PUBLICATIONS
Allowance Lists, and Aviation Training Litera Training Literature (00-80 Series)
ture .
This series of publications is issued by au
thority of the Deputy Chief of Naval Operations
Allowance Lists and Outfitting
Lists ( 00-350 Series) ( Air ). Included are various Air Safety Pamphlets
and General Aviation Training Publications. All
such publications listed in the current issue of
Allowance Lists and Outfitting Lists consist the Numerical Index are available at the various
of listings of the equipment and material neces NavAir Publications Supply Points. All requests
sary to place and maintain various activities in a
for 50 or more copies of a publication must be
material readiness condition . These allowances submitted to the Chief of Naval Operations,
are based on known or estimated requirements Flight Training Branch , Washington , D. C. , with
or on available usage data. a statement of justification .
Allowance Lists are identified by SECTIONS.
Certain sections such as A, H, and K are issued
as individual publications. Others such as B and AIRCRAFT MANUALS ( 01 SERIES )
R appear as a series of publications , each of
which is applicable to a specific model of The following types of manuals are prepared
equipment , model of aircraft, or type of and issued for each model of aircraft used by the
activity . Navy :
The AMS should be familiar with the
following sections : NATOPS Flight Manual.
Maintenance Instructions Manual .
Section A , Standard Aeronautical and Navy
> Structural Repair Manual.
Stock Account Material . Periodic Maintenance Requirements Manual
Section B, Airframe and Engine Maintenance or Periodic Maintenance Information Cards.
Parts. This section contains the initial outfitting Illustrated Parts Breakdown .
list for each model of aircraft in current use. Technical Manual of Weight and Balance Data
Section G , General Support Equipment . This (certain aircraft only ) .
section lists all consumable general support
equipment for all classes , types, and models of NATOPS Flight Manual
aircraft.
Section H , Flight Operational Material for The NATOPS (Naval Air Training and
Aircraft Squadrons. This section lists aviator's Operating Procedures) Flight Manual contains
flight clothing as well as the protective clothing complete operating instructions for the aircraft
available for use when handling liquid oxygen . and
its operational equipment. Emergency
Section K , Allowance List for Naval Aero operating instructions as well as normal
nautic Publications and Forms. operating instructions are provided. Although
Allowance Lists are reissued periodically. NATOPS Flight Manuals are issued primarily for
When new issues or reissues are published , they the use of pilots and aircrewmen , all main
are listed in the next issue of the Numerical tenance personnel should become familiar with
Index . All lists not appearing in the current issue the contents of the Flight Manual for their
of the Numerical Index or latest supplement respective aircraft.
have been canceled . NATOPS Flight Manuals are kept up to date
All Allowance List and Outfitting List code by two types of revisions - regular revisions and
numbers are NA 00-350 plus the section interim revisions . Regular revisions cover routine
identification letter and a dash number to changes and instructions and are generally issued
identify a particular section in a series. For every 90 days . Interim revisions cover vital
example , the Section B Allowance List for the operating instructions and are used when im
S-2D aircraft is NA 00-35QB - 177 . This publica mediate action is necessary . Interim revisions
tion contains the initial outfitting list for the may be issued in letter form to the individual
S-2D aircraft . activities and by naval message to commands,
17
and are later incorporated as regular revisions. Flight Control Systems.

Corrosion Control , Cleaning, Painting, and
Maintenance Instructions Manuals Decontamination .
The Maintenance Instructions Manuals NOTE : The different aircraft manufacturers

(MIM's) contain all the essential information may group the material in the various volumes
required by aircraft maintenance personnel for of the Maintenance Instructions Manuals under
service and maintenance of the complete air different titles. For example, the Survival and
craft. MIM's include the data necessary for Environmental Systems volume for the RA -5C
troubleshooting and maintaining the power covers the ejection seat , canopy, liquid oxygen ,
plant , accessories , and all other systems and heating, air -conditioning, ventilation , and anti-g
components of the aircraft . systems. Two volumes, titled Personnel Environ
Maintenance Instructions Manuals are divided
mental Systems and Canopy and Survival Sys
into three types . Type I manuals contain all tems, are prepared to cover the same subjects for
essential information required for performing the A-4 aircraft.
Organizational level maintenance , such as The General Information
Information and Servicing
description and operation of systems and volume is designed primarily for the plane
components, maintenance considerations, and captain ; however , this volume also contains a
appropriate diagrams and schematics . great deal of information important to all AMS
Type II manuals contain Intermediate level personnel . This volume contains a general
maintenance instructions required for the main description of the aircraft, all necessary informa
tenance of components , systems, groups of tion which is not contained in other specialized
systems , or equipment when separate coverage is manuals, and all information pertaining to
>
not provided in other manuals. Included are servicing the aircraft.

procedures for checkout , troubleshooting, Each of the specialized system volumes of the
repair , replacement , adjustment, calibration , and Maintenance Instructions Manual is further
preinstallation , and/ or shipping information divided into four sections, as described in the
( method of packaging ) . Coverage on following paragraphs.
components or equipment may include a Section 1 is the same in all volumes of a
description of component operation if it is not particular aircraft Maintenance Instructions
covered in the Type I manual .
Manual . This section provides an introduction to
Type III manuals contain Depot level over the manual and usually supplies a list of the
haul and repair instructions for components , Changes applicable to the particular volume
accessories , and any other equipment necessary concerned .
for unit operation . Section II describes the system and
In many cases, a consolidation of any components as well as their operation.
combination of Types I , II , or III manuals is Section III provides such maintenance
provided in one manual . This is the type coverage as removal and installation procedures
discussed in the following paragraphs and most and troubleshooting charts for Organizational
common to the AMS. level of maintenance .
The Maintenance Instructions Manual for all Section IV provides component repair proce
current production aircraft is made up in dures for the Intermediate level of maintenance .
volumes , each volume being individually bound Figure 2-2 is an example of a page from
and issued separately . This permits each shop in section III of a Maintenance Instructions
an activity to have its own applicable volume , or Manual . This page shows the basic layout of the
volumes , at hand for ready reference. Volumes maintenance - coverage sections of the specialized
of most interest to the AMS are as follows: type manuals. Each component maintenance
procedure is identified by a boldface heading
General Information and Servicing. (item A, fig. 2-2 ) for ease in locating the
Landing Gear and Arresting Gear Systems. material on the page. All removal and installa
Airframe and Related Systems . tion procedures provide a recommended man
18
Chapter 2-AERONAUTIC PUBLICATIONS
Section It NAVAIR01-75PAA 2-2.3

Paragraphs 3-328 to 3-33)
Removal Procedure Altach brackets to structure using NAS623 307
screws and ANAGODIO washers in the two ypper and
a. Remove elevators ( refer to paragraph 33:1). two lower fotes. Use NAS623-3G screws and ANIGOD :LO
b . Removethree screws from each bracket assembly washers in the(womiddle holes:
and remove damper, h . Inspect attachment of brackets to structure. Damper
c. Remove bolts, nuts and washers which retain con : must rotate freely and there must be a minimum of 0.12 E
necting rod assemblies to damper arms. inch clearance to structure.
d. Remove nut; washer and spacers from top and Reinssst elevapors (Refer to paragraph 3:332.:)
bottom brackets and remove brackets, leaving damper
Quality Assurance Summary
assembly
Note a. Inspect installation of upper and lower brackets to
The viscarus damper assembly must be stored
damper assembly to check nut and cotter pin installation.
with the topside up. If stored with thetopside b. Inspect installation of upper and lower rod assem
upside down for more than four hours, blies for tightness of attachments and lock -wiring of F
lower bolt head .
possible that air may be entrapped in the fluid
between the disc and the housing, thus reducing c. Inspect attachment of brackets to structure. Damper
damping rate. This condition can be corrected must rotate freely and there must be a minimum of 0.12
by stodng the damper in its normal position inch clearance to structure.
ac nom temperature, approximately 21,140
(70 ° F ) for one week 3-330 . ELEVATOR MAINTENANCE А.
A
PROCEDURES .
3-328. REPAIR AND PARTS REPLACEMENT
3 :331. REMOVAL (Sze fourt 3-105
Spares and Repair Parts Data
Forward to next higher maintenance level: Tools and Equipment List
Truck , Fork Lift TC - 200 с
3-329 . INSTALLATION Hoist HSKS - 1531B
Materials List Elevator Sling Assembly 551241-1
Cotter Pin ( 2 ) MS24665-300 Manpower Requirements

D 923033-1
B
Spacer ( top ) Two men are required.
Spacer ( bottom ) 923033-3
Removal Procedure
Manpower Requiremene a placand control column.
Oneman is required. b , Open six afc fadome Marches and roll radome back
on track
Quality Assurance Requitement c. Support the elevator withelevator sting Assembly,
An inspectionis required when stepsappear in ildlirs. LCO 5512411 or equivalent and move the elevaror to
she up position
Inscalfäcian Procedure d. Remove che lock wire and two bolts craching clin
* Install upper bracket using one 923033-1_spaceti inboard end of the elevator to the end fittit g of the ele
AN320-5 nut and MS24665-300 correr pan. vatør porque tube.
b . Install lower bracket using one 923033-3 spacer, e. Move the elevarotco thedownt position and teinove
AN320-5 nut and MS2466-300 colterpin. one bole attachingthe elevatorto che torquetube
f. Open the four hinged boli access panelslocated
E c. Inspect installation of upper and lower bearing across the underside of the hotizontal stabiltzer Ettling
brackets to check nut and coiter pin installation. odgs, and panel E207 L / R on top trailing edge of the
d. Install upper tog assembly using an NAST10417 fiorizontal stabilizer:
bolt and NAS679A4Wnur with an ANGGODA16 wastet
g Disconnect the two viscous damper push tods
under the bolt head and under the nuc Bolt head is up: located at hotizonrat scabilizer station 93,84.
e, Install lowerrod assembly using an AN174H13. h . Disconnecta roll, tape and stow elevador trim tab
bail agid NASGIDA W nut with an ANOG0D416 washer cables for removal with the elevator Turnbuckles for
under the bolt head and under the nuc Bolthead is the riglit elevator trim cäb are disconnected in the fuse.
down. Lock:wire boli head co lower lever, lage rail tone area. Turnbuckles for theleft elevatot trim
f. Inspect installation of upper and lower rod assem . cab are disconnected by gaining access through E206 1
E blies for tightness of attachments and lock-wiring of access panel on the trailing edge of the lowerleft horr
lower bolt head . zontal subilizer
3-294
AM.225
Figure 2-2.- Typical page of a Maintenance Instructions Manual .
19
power requirement ( item B ) for the shop chief's and contains information for use at Intermediate
use in assigning personnel to perform the job . and Depot level facilities.
All tools and equipment other than standard The Structural Repair Manual is identified by
tools are noted (item C) ahead of the main a “ -3 ” in the manual publications code ( fig. 2-1 ) .
tenance procedure, so that these items may be The two volumes are further identified by an
drawn from the toolroom prior to starting the additional dash number . An example of the code
operation. for a Structural Repair Manual in current use is
When consumable materials such as lubri NA 01-75PAA -3-1. This is the code for Volume
cants , lock wire , and cotter pins are required I of the Structural Repair Manual for the P-3A
during an installation procedure , a listing of aircraft.
these items (item D) is made ahead of the Each volume of the Structural Repair Manual
procedural steps . Miscellaneous small parts is divided into sections . Section I contains
(other than standard AN and MS hardware), information of a general nature . Each of the
which are necessary for removal and installation , other sections contains information of a more
also appear in the materials list . specific nature . These sections cover portions of
As an aid to Quality Assurance Representa the aircraft such as wings, tail, fuselage, alighting
tives, those steps in a procedure which require gear , and engines. There is also a section
an inspection are set in in italics (items marked covering typical repairs .
E). (NOTE : In some MIM's the steps in a Before attempting to use the Structural
procedure which require a Quality Assurance Repair Manual, the mechanic should read the ·
inspection are underlined . ) These italicized steps introduction to Volume I. Included in the
are a very important feature and are summarized introduction is information concerning the use
(item F) at the end of each procedure . of the manual . NOTE : Since the format of the
Classified maintenance information is not various Structural Repair Manuals may differ,
included in the regular volumes of the Main the instructions in the introduction may differ
tenance Instructions Manual . Essential classified slightly .
information is contained in separate volumes or The Structural Repair Manual is sup
supplements of the Maintenance Instructions plemented by the NA 01-1A Series general
Manual , which are classified “ confidential.” manuals .
Classified volumes of the Maintenance Instruc
tions Manual are bound in red in order that they Periodic Maintenance
may be readily identified . These volumes must Requirements Manual
be handled in accordance with the Department
of the Navy Security Manual for Classified This manual contains the complete require
Information (OpNav Instruction 5510.1 Series) . ments for inspection of the aircraft, its
components, and accessories. The inspection
Structural Repair Manual requirements are stated in such a manner as to
establish what equipment is to be inspected ,
The Structural Repair Manual is used as a when it is to be inspected , and what conditions
guide in making structural repairs to the air are to be sought . It does not contain instructions
frame. It contains general information such as for repair, adjustment , or other means of
airframe sealing, control surface rebalancing , correcting defective conditions, nor does it
general shop practices, damage evaluation and contain instructions for troubleshooting to find
support of structure , and a description of the causes for malfunctioning.
structure through the medium of indexed il
lustrations and repair drawings. Periodic Maintenance
The Structural Repair Manual for most new Requirements Data
aircraft is published in two volumes . This is not
due to its size but is to suit its usage by different The Periodic Maintenance Requirements
facilities. Volume I is for use at all levels of Manuals are being replaced by periodic main
maintenance. Volume II supplements Volume I tenance requirements data contained in three
20
types of publications - Periodic Maintenance In ment , and special support equipment subject to
formation Cards (PMIC ), Maintenance Require separate maintenance .
ments Cards (MRC ), and Sequence Control
Charts ( SCC ). The latest type IPB has a separate volume for
the Numerical Index . The Numerical Index
The PMIC's have a listing of items having an
approved mandatory replacement interval and contains an alphanumeric listing of all the parts
those items requiring scheduled removal in the IPB or volume . In addition to the part
numbers , the Numerical Index contains such
component cards as defined in OpNav Instruc
tion 4790.2. information as federal stock number data , figure
They also contain a maintenance reference and index numbers , source code data , and
table that lists those publications which have recoverability information .
been incorporated in the maintenance require The number of IPB manuals for some aircraft
ments since the last revision . are numerous and for this reason some of the
The Maintenance Requirements Cards and the aircraft manufacturer's have published a Master
Sequence Control Chart are discussed in Military Locator Index in conjunction with their IPB.
Requirements for Petty Officer 3 & 2 , NavPers This Master Locator Index is used to locate the
10056 - C , Chapter 14 . IPB manual in which the part number is shown
when only the part number is known . Most
Master Locator Index pages are divided into 4
Illustrated Parts Breakdown columns , each containing a part number and a
manual number column . The number shown in
the " Manual Number" column is the last dash
The purpose of the Illustrated Parts Break number of the NavAir IPB manual in which the
down (IPB) is to assist supply , maintenance , and
>
part will be found . Example : Part No.
overhaul personnel in the identification , requisi 128B10855 , for an A-6A Aircraft , listed in the
tioning, storing , and issuing of parts for the Master Locator Index , shows a “ 3 ” in the
applicable aircraft. " Manual Number" column . This means that
The IPB for older aircraft, like the Main complete information on the part will be found
tenance Instructions Manual , may be found in in A-6A IPB, NavAir 01-85 ADA 4-3. Once
one volume . The IPB prepared for current directed to a specific volume of the IPB the part
production aircraft contains several volumes, can be further traced through the use of that
which usually correspond to the volumes in the volume's numerical index .
Maintenance Instructions Manual .
The IPB , like the Maintenance Instructions Prior to using any volume of the IPB , all of
the information in Section I should be read . The
Manual , has a code number. A “ -4 ” in part III of information contained in this section will aid the
the publications code (fig. 2-1 ) identifies the
AMS in locating the necessary part or parts
IPB . The individual volumes of the IPB are
identified by an additional dash and number . An quickly and easily .
example of the code number for an IPB in
current use is NA 01-60ABC -4-3 . This is the
code number for the Mechanical Controls Technical Manual of
volume of the RA- 5C IPB . Weight and Balance Data
Each volume of the IPB is divided into at least
two sections and sometimes three - Section I , This manual provides a standard system for
Introduction , Section II , Group Assembly Parts field weight and balance control of certain
List , and Section III , when used , Numerical aircraft. The forms, charts, and records in this
Index . The Introduction ( Section I ) contains manual are prepared by the manufacturer prior
detailed instructions for the use of the IPB. to delivery of the aircraft to the Navy and
Section II includes illustrations of all parts of provide the means of maintaining a continuous
the applicable aircraft and its systems, equip and current record of the basic weight and
21
balance and loading information during the provide adequate instructions for operating the
aircraft's service life . item and maintaining it throughout its service
Procedures and instructions for maintaining life. Accessories Manuals therefore contain
the weight and balance records are contained in descriptive data ; detail instructions for installa
the manual. These records must be maintained tion , operation , inspection , maintenance, and
by operating and overhaul activities and must be overhaul; and an illustrated parts list . All Acces
brought up to date ' prior to transfer of the sories Manuals available for issue are listed in
aircraft. The manual must be retained in the numerical order (by publication number) in the
aircraft at all times. Accessories Section of Part C , Section VIII of
NavSup Publication 2002. They are also listed in
00-500A , but in alphanumeric order according
General Aircraft Manuals ( 01 Series) to part number. In 00-500B , Accessories
Manuals are listed under the aircraft in which
the accessory is installed .
To avoid confusion between the General Accessories Manuals are used to supplement
Manuals ( 00 series) and general Aircraft Manuals information found in the aircraft Maintenance
(01 series) , an explanation is in order at this Instructions Manual . For example , when the
point . This chapter is concerned with Maintenance Instructions Manual does not give
AERONAUTIC publications. There are many instructions for repairing a particular item ,
general aeronautic publications that do not reference should be made to the applicable
directly concern aircraft ; these are in the 00 Accessories Manual .
series. There are other manuals that are ap
plicable to aircraft in general without being If an accessory is relatively simple , all the
identified with a specific model ; these are necessary instructions may be contained in a
general AIRCRAFT manuals . Some general air single manual . An example is NA 03-25 BA-19 ,
craft manuals with which the AMS works are as Overhaul Instructions with Illustrated Parts
follows: Breakdown for a landing gear wheel manufac
tured by the B. F. Goodrich Company.
NA 01-1A - 1, General Manual for Structural More complex accessories may require two or
Repair . more manuals. For example , one manual may
cover operation , service , and overhaul instruc
NA 01-1A-8 , Aircraft Structural Hardware
for Aircraft Repair. tions , while the parts breakdown is contained in
a separate manual.
NA 01-1A -509, Aircraft Cleaning and Cor
rosion Control for Organizational and Inter To determine what manuals are available for a
mediate Maintenance Levels. particular accessory , proceed as follows:
If the name of the manufacturer and the
model/ part number of the item are known , turn
ACCESSORIES MANUALS ( 03 SERIES)
to the alphanumeric part number listing in
NavAir 00-500A and locate the item. All
The 03 series manuals cover all types of manuals applicable to that particular item of
accessories . An accessory is defined as any item equipment will be listed by code number along
of equipment which is required for operation of with the item nomenclature .
the aircraft and which cannot be considered an
integral part of the airframe or engine . Examples
of accessories for which the AMS is responsible SUPPORT EQUIPMENT MANUALS
are aircraft wheels and helicopter rotor com ( 17 , 18 , AND 19 SERIES )
ponents.
The manufacturer of each item of support
The manufacturer of each item of equipment equipment is required to furnish adequate
(wheels, valves, cylinders , etc. ) is required to instructions for operating the equipment and
22
maintaining it throughout its service life. Like personnel to injury or property to loss or
aircraft Maintenance Instructions Manuals and damage .
Accessories Manuals, these publications prepared Safety precautions shall be posted in a
by the manufacturer are issued under the au conspicuous place on or near any equipment,
thority of the Naval Air Systems Command and component, or material which presents a hazard
are then official Navy publications. to the security of the activity or to the safety of
The 17 and 18 series of aeronautic manuals
personnel. For example , those precautions
necessary for the safe handling, stowage , and
provide information and instructions for most
security of dangerous materials such as
tools , machinery, and test equipment used in explosives or flammables shall be posted at or
support of aircraft and components. Each item near the storage spaces designated for those
is covered by a manual which contains the materials .
purpose , procedures for preparing the item for Each individual is responsible for knowing ,
use , operation , inspection , maintenance, lubrica understanding, and observing all safety pre
tion , troubleshooting , and other pertinent data .
cautions applicable to his work and work area .
The 19 series manuals contain information on All chapters of the Safety Precautions Manual
ground servicing and automotive equipment are extremely important, and the AMS should
related to performing aircraft maintenance. be especially concerned with the chapter titled
Aviation . This chapter covers general pre
Support Equipment Manuals are stocked , cautions applicable to the maintenance, repair ,
cataloged , listed , and located in the same and overhaul of aircraft.
manner as Accessories Manuals.
NOTE : Ground support equipment data
formerly provided as Descriptive Data Sheets TECHNICAL INFORMATION FILE
( 20 Series publications ) are now identified as
OF GROUND SUPPORT EQUIPMENT
Ground Support Equipment Illustrations
(GSEI ) . This information is coordinated with (MIL -HDBK - 300B )
other branches of the service and is published
and identified as MIL-HDBK-300 .
r This publication is intended to provide , in
у concise and convenient form , factual pictorial
and descriptive data to familiarize designers,
en SAFETY PRECAUTIONS MANUAL engineering, maintenance and training personnel
( NAVMAT P- 5100 SERIES ) and Government contractors with the charac
teristics, performance capability and physical
а
makeup of the ground support equipment
The safety precautions contained in this presently in the inventory of the military
he manual are applicable to all Navy personnel, services and under development for use with
arn military and civilian, and to all naval commands aircraft and missile systems . In the case of
in and activities . They are of necessity basic and Government contractors , the data sheets are
All general in nature and are not inclusive of all intended to provide sufficient information for
of conceivable operations and functions involved in determining that an item of equipment is
song the great variety of Navy activities. In many suitable or unsuitable for a contemplated ap
instances references are made to other publica plication. This will insure the following:
tions for detailed safety precautions applicable
to specific conditions . A lack of documented 1. Maximum usage of in -service assets.
hazards and pertinent precautions is not to be 2. Elimination of duplicate design or develop
construed as an indication of their nonexistence ment of ground support equipment for different
or unimportance; therefore, the continuous weapon systems .
oport cooperation and vigilance of all personnel is
uate needed to see that all operating procedures and This handbook contains information on
and work methods do not unnecessarily expose ground support equipment for aircraft and
23
missile weapon systems . Ground support equip cannot be satisfactorily disseminated by revi
ment is construed to include ground operation, sions or changes to technical manuals. This
handling , and servicing equipment . Ground information is disseminated in the form of
support equipment is further defined as all Changes , or in the case of special circumstances ,
equipment required on the ground to make a by Interim Changes or Bulletins.
weapon system operational in its intended A formal TD is a document issued as a
environment. Change , or as an Amendment or Revision
Data sheets for the Technical Information thereto , and promulgated by letter . Formal
File (TIF) will normally be selected or sub technical directives are used to direct the ac
mitted only for ground support equipment items complishment and recording of modifications to
that have a unit cost of $ 1,000 and over or a weapons , weapons systems, support equipment , >
potential or actual procurement total dollar trainers , and related equipment and are
value in excess of $ 100,000 , regardless of unit comprised of Changes and Amendments and/or
cost . Revisions thereto .
Data sheets will not normally be acquired or An interim TD is a document issued as a
submitted for common tools or power tools Bulletin or a Change , or as an Amendment or
normally found in a standard machine shop ; Revision thereto , and promulgated by message
component parts or sub -assemblies of end items ; to insure speedy dissemination . The interim TD
kits , sets of tools , fixtures for manufacturing in is reserved for those instances requiring im
depot use ; sling, adapters , small containers , mediate correction of an operational or safety
cabinets ; or obsolete items of supply . condition which embodies risks calculated to be
This handbook supersedes individual descrip intolerable within the lead time of a formal
tive data sheets which were previously issued directive or maintenance publication change.
separately for each item of support equipment Interim Changes are superseded by a Formal
not covered by an individual technical manual . Change directive which will have the same
number as the interim directive . Interim Bulletin
directives are not superseded by formal Bulletins
as was previously the case . The NavSup Publica
LETTER TYPE PUBLICATIONS tion 2002 , Section VIII , Part D , will still have
many formal Bulletins listed until they are
TECHNICAL DIRECTIVES eventually phased out .
A Change is a document containing instruc
The Technical Directive (TD) System has tions and information which directs the ac
been established for control and issue of all complishment and recording of a material
technical directives . This system standardizes the change, a repositioning , a modification , or an
method of issuance for such directives and is the alteration in the characteristics of the equipment
authorized means for directing the accomplish to which it applies . A Change is issued to direct
ment and recording of modifications and that parts be added , removed , or changed from
9
one -time inspections to equipment procured by the existing configuration or that parts or
and for the NavAirSysCom . The TD system is an material be altered , relocated, or repositioned .
important element in the programs designed to A Change may be issued in parts to ac
maintain equipment in a configuration which complish distinct parts of a total directed action
provides the optimum conditions of safety , or to accomplish action on different configura
operational, and material readiness. The system tions of affected equipment . A Change may also
encompasses two types of technical directives be issued for record purposes . A Record Purpose
differentiated by their method of dissemination . Change is a TD issued to provide documentation
These two types are Formal (letter type) and of a modification which has been completely
Interim (message type ) . In general terms, they incorporated by the contractor or inhouse
are both considered as letter type technical activity in all accepted equipment and which
directives. Such directives contain instructions does not require retrofit or the modification of
or information of a technical nature which repairables in the Navy's possession .
24
An Amendment is a document comprised of Photographic.

information which clarifies , corrects, adds to, Support Equipment .
deletes from , makes minor changes in require Airborne Weapon .
ments to, or cancels an existing technical Clothing and Survival Equipment .
directive. It is only a supplement to the existing Target Control System.
directive and not a complete directive in itself. A Meteorological Equipment .
maximum of three Amendments may be applied
to any TD, each remaining in effect until If the technical directive involves safety of
rescinded or superseded by a Revision . A flight, the word “ SAFETY ” will appear im
requirement for further amendment action mediately following the title and number.
necessitates the issuance of a Revision . Technical directives are numbered by two
A Revision is a completely new edition of an different methods .. Some are numbered
existing technical directive . It supersedes the consecutively from the beginning of the calendar
original directive or revision and all existing year with the last two digits indicating the year
Amendments . of issue. Thus, a Change or Bulletin designated
A Bulletin is an interim document comprised 47-54 would be the 47th change or bulletin of
of instructions and information which directs an that type issued in 1954. This type of number
initial inspection to determine whether a given ing system is no longer being used for identify
condition exists . It specifies what action is to be ing new directives . However , those which have
taken if a given condition is found or not found . been numbered in this manner and are still in
Interim Bulletin directives are self- rescinding effect are cataloged under this system .
with rescission dates of 30 June or 31
The present numbering system is a conse
December , whichever is appropriate for the case
cutive numerical application regardless of the
at hand . Rescission is the process by which the year of issue. For example , F - 4 Airframe Change
TD's are removed from active files after all
requirements have been incorporated. Final 204 would be the 204th Airframe Change that is
rescission action is directed in the TD Index , applicable to the F-4 aircraft. This numbering
NavSup Publication 2002 , Section VIII , Part D. system has been in effect for some time and
All activities maintaining active technical most technical directives are cataloged under
libraries must maintain the TD's on file until
this system .
they are deleted from the TD Index . The numbers assigned to Changes and
Cancellation of a technical directive is the
Bulletins are provided by the Technical
process whereby the TD is removed from the Directives Control Center , which is located at
the Naval Air Technical Services Facility
active files when it is determined that a previous
ly issued TD is not to be incorporated . Cancella ( NATSF ), Philadelphia . Changes or Bulletins
that have been amended will have their basic
tion is directed by the issuance of an Amend
number followed by the words " Amendment
ment to the TD. The cancellation explicitly 1 , " " Amendment 2 , " etc. A revised directive
states the required configuration of each article
will have the basic directive number followed
initially specified for modification , for example,
whether installed modifications are to remain with the words " Rev. A ," " Rev. B ," etc. , as
installed or are to be removed , etc. appropriate to denote the first, second , etc. ,
revisions to that basic directive .
The title subject of a Change or Bulletin will
be one of the following, as appropriate : The Changes and Bulletins are automatically
distributed to all concerned activities through
Airframe. inclusion on the Mailing List Request for Aero
Powerplant . nautic Publications, NavAir Form 5605/3 . All
Avionics . TD's are issued by NavAir or NavAir Tech SerFac
Accessory . except in cases where the time delay in obtain
Aviation Armament . ing approval is unacceptable . In such cases the
Aircrew System . controlling custodians are authorized to issue
Propeller. interim TD's to preclude unacceptable risks to
25
personnel or equipment . The Changes or Bulle scheduled basis , not later than 18 months after
tins are generally based on Contractor Service the date of issuance .
Bulletins, other letters of recommendation , or Routine Action directives are issued where
proposed modifications from field service activ there are reliability , capability , or maintain
ities . ability deficiencies which could , if uncorrected ,
become a hazard through prolonged usage or
Directive Categories have an adverse effect on the operational life or
general service utilization of equipment . The
Technical directives are assigned a “ category ” conditions embody a degree of risk or require
ment determined to be tolerable within a broad
in accordance with the importance and urgency
time limit . The compliance requirement specifies
of accomplishing the work involved . A category the incorporation of the instructions not later
of Immediate , Urgent, Routine , or Record
Purposes is assigned each technical directive. than the next regularly scheduled overhaul or
rework , or for equipment not reworked or
The category “ Immediate Action ” is assigned overhauled on a scheduled basis , not later than
to directives which are issued to correct safety
conditions , the uncorrected existence of which 18 months after issuance of the directive . If
would probably result in fatal or serious injury accomplishment of the work requires Depot
to personnel , extensive damage , or destruction level maintenance capability , the compliance
of property. Immediate Action directives involve may be deferred if it will seriously interfere with
operational commitments or schedules .
the discontinued use of the aircraft, engines , or
Routeine Action directives are identified by the
equipment in the operational employment under words " ROUTINE ACTION ” printed in black
which the adverse safety condition exists , until
the directive has been complied with. If the use capital letters at the top center of the cover
page .
of the aircraft, engines, or equipment will not
involve the use of the affected component or The category “ Record Purposes ” is used on a
system in either normal or emergency situations, technical directive when a modification has been
compliance may be deferred , but should be completely incorporated by the contractor or
accomplished no later than the next periodic in - house activity in all accepted equipment and
inspection for the aircraft and no later than 120 when retrofit is not required on repairables in
days from the date of issue for the equipment . the Navy's possession . They are identified by the
The Immediate Action directive is identified by words “ RECORD PURPOSES" printed in black
a border of red X's broken at the top center of capital letters at the top center of the cover
the page by the words " IMMEDIATE page . This type of TD merely documents the
ACTION ,” also printed in red . action for configuration management purposes;
The category " Urgent Action ” is assigned to therefore , compliance information is not ap
directives which are used to correct safety plicable and is indicated as such .
conditions which , if uncorrected, could result in
personnel injury or property damage . Such
conditions compromise safety and embody risks INSTRUCTIONS AND NOTICES
calculated to be tolerable within narrow time
limits and may or may not necessitate the Instructions and Notices are directives
imposition of operating restrictions . Urgent containing information and instructions
Action directives are identified by the words concerning policy, administration , and air opera
“ URGENT ACTION ” printed in red ink at the tions . They are issued by all bureaus , systems
top of the first page and a border of red commands , ships, stations, and operating
diagonals around the cover page. activities . Those issued by the Naval Air Systems
The compliance requirement specifies that the Command are known as NavAir Instructions and
incorporation of the instructions must be ac Notices.
complished not later than the next regularly Instructions are directives of a continuing
scheduled rework or overhaul or for equipment nature and are effective until canceled or super
not reworked or overhauled on a regularly seded by a later directive.
26
Notices are directives of a one-time nature or by the U. S. Naval Aviation Safety Center and is
directives which are applicable for a brief period distributed to all naval aeronautic organizations
of time . Each Notice contains a provision for its on the basis of 1 copy for every 10 persons. It
own cancellation . presents the most accurate information current
Instructions are numbered in consecutive ly available on the subject of aviation accident
order according to the subject covered in the prevention.
Instruction . Notices are numbered according to A large number of aviation accidents are
the subject covered and serialized by the date of maintenence-induced ; that is , they occur during
issue . They may be addressed to “ All Ships, preparation for, performance of, and securing
Stations , and Units concerned with Naval Air from maintenance or as a result of sloppy or
craft ," or to certain activities only . Each activity improper maintenance . For instance , one
maintains a file of all pertinent Instructions and fatality was reported which occurred when a
Notices still in effect. maintenance man unintentionally ejected him
self while arming an ejection seat . Additionally ,
a recent statistic reported in Approach revealed
MISCELLANEOUS AVIATION that in 9 accidents during a recent 15 -month
I PUBLICATIONS period 9 aircraft were lost - 9 million dollars lost
2
due to the omission of 9 cents worth of cotter
n Several other unofficial publications of pins.
S. general interest to aviation personnel are avail The Approach magazine reports the results of
able in most operating activities . These should accident investigations ; and for those accidents
e
be read regularly by all maintenance personnel. that are maintenance-induced , describes what
K
was done wrong and how it should have been
EI
NAVAL AVIATION NEWS done; suggests corrective measures to prevent
future accidents resulting from these causes ; and
a when appropriate , cites aeronautic technical
n
The Naval Aviation News , NavAir 00-75R - 3,
is published monthly by the Chief of Naval publications which provide authority for
of changes in techniques or material to improve the
d
Operations and the Naval Air Systems Com maintenance product .
mand . Its purpose is to disseminate data on
un In short , the maintenance man who reads and
ne
aircraft training and operations , space tech
nology , missile , rocket , and other aviation heeds the messages in Approach is the man who
ck benefits from other mechanics' experiences. Put
ordnance developments , aeronautical safety , air
21
craft design , powerplants, aircraft recognition, Approach on your required reading list and look
he for it every month .
technical maintenance , and overhaul procedures.
S;
As its name implies , this publication is es
P sentially a news magazine. It enables readers to
keep abreast of the latest unclassified develop
ments in every facet of naval aviation . In ad MECH
dition , the coverage of fleet operations and the
human interest articles on the noteworthy feats MECH is published quarterly by the U.S.
and accomplishments of individuals , both officer Naval Safety Center and is distributed to naval
es
and enlisted , make the Naval Aviation News an aeronautic organizations on the basis of 1 copy
7S
entertaining as well as an informational per 10 persons. It presents the most accurate
a
periodical . information available on maintenance - caused
7S
mishap prevention and general aviation ground
ng APPROACH safety . Contents are informational and should
ms
not be considered as regulations, orders , or
d Approach , NavAir 00-75-510 , The Naval directives. Reference to commercial products
Aviation Safety Review, is published monthly does not imply Navy endorsement .
7g
Er
27
CHAPTER 3
AIRCRAFT MATERIALS
In this chapter we will discuss the properties, aircraft maintenance and repair, even a slight
characteristics, and uses of various materials deviation from design specifications or the
used in the construction of aircraft, primarily substitution of inferior materials may result in
metals and plastics . An AMS should have a the loss of both lives and equipment . The use of
knowledge and understanding of these proper unsuitable materials can readily erase the finest
ties, characteristics, and uses in order to inspect, craftsmanship . The selection of the specific
maintain , and repair the airframe properly.
> material for a specific repair job demands
An AMS is required to inspect metals for flaws familiarity with the most common properties of
and defects. Therefore, information on the various metals .
general procedure for the inspection of metals
using the dye penetrant method is also dis PROPERTIES OF METALS
cussed .
This section is devoted primarily to the terms

AIRCRAFT METALS
used in describing various properties and charac
teristics of metals in general . Of primary concern
in aircraft maintenance are such general proper
Metallurgists have been working for more ties of metals and their alloys as hardness,
than a half century improving metals for aircraft
construction. Each metal has certain properties
malleability , ductility, elasticity, toughness,
density, brittleness , fusibility , conductivity ,
and characteristics which make it desirable for a
contraction and expansion , etc. The AMS must
particular application , but it may have other know the definition of the terms included here
qualities that are undesirable . For example , as they form the basis for further discussion of
some metals are hard , others comparatively soft; aircraft metals .
some are brittle , some tough; some can be
formed and shaped without fracture; and some
are so heavy that weight alone makes them Hardness
unsuitable for aircraft use . The metallurgist's
objectives are to improve the desirable qualities Hardness refers to the ability of a metal to
and tone down or eliminate the undesirable resist abrasion , penetration , cutting action , or
ones. This is done by alloying (combining) of permanent distortion. Hardness may be in
metals and by various heat -treating processes. creased by working the metal and , in the case of
One does not need to be a metallurgist to be a steel and certain titanium and aluminum alloys,
good AMS, but he should possess a knowledge by heat treatment and cold -working (discussed
and understanding of the uses, strengths, limita later). Structural parts are often formed from
tions, and other characteristics of aircraft metals in their soft state and then heat treated
structural metals. Such knowledge and under to harden them so that the finished shape will be
standing is vital to properly construct and retained . Hardness and strength are closely
maintain any equipment , especially airframes. In associated properties of all metals.
28
Chapter 3 - AIRCRAFT MATERIALS
Brittleness members and parts are so designed that the

maximum loads to which they are subjected will
Brittleness is the property of a metal which never stress them beyond their elastic limit.
allows little bending or deformation without (NOTE : STRESS is the internal resistance of
shattering. In other words , a brittle metal is apt any metal to distortion . ) This desirable property
to break or crack without change of shape. ( elasticity ) is present in metals used for making
Because structural metals are often subjected to springs.
shock loads, brittleness is not a very desirable
property . Cast iron, cast aluminum , and very
> Toughness
hard steel are brittle metals.
A material which possesses toughness will
Malleability withstand tearing or shearing and may be
stretched or otherwise deformed without break
A metal which can be hammered , rolled , or ing. Toughness is a desirable property in aircraft
metals .
pressed into various shapes without cracking or
breaking, or other detrimental effects, is said to
be malleable . This property is necessary in sheet Density
metal which is to be worked into curved shapes Density is the weight of a unit volume of a
such as cowlings, fairings, and wingtips. Copper material . In aircraft work , the actual weight of a
is one example of malleable metal . material per cubic inch is preferred since this
figure can be used in determining the weight of a
Ductility part before actual manufacture . Density is an
important consideration when choosing a mate
Ductility is the property of a metal which rial to be used in the design of a part and still
permits it to be permanently drawn, bent , or maintain the proper weight and balance of the
twisted into various shapes without breaking. aircraft.
This property is essential for metals used in
making wire and tubing . Ductile metals are Fusibility
greatly preferred for aircraft use because of their
ease of forming and resistance to failure under Fusibility is defined as the ability of a metal
shock loads. For this reason , aluminum alloys to become liquid by the application of heat.
are used for cowl rings, fuselage and wing skin , Metals are fused in welding. Steels fuse around
and formed or extruded parts, such as ribs, 2,500° Fahrenheit ( F) and aluminum alloys at
spars , and bulkheads. Chrome-molybdenum steel approximately 1,110° F .
f is also easily formed into desired shapes.
Ductility is similar to malleability . Conductivity
Elasticity Conductivity is the property which enables a

metal to carry heat or electricity . The heat
Elasticity is that property which enables a conductivity of a metal is especially important
o metal to return to its original shape when the in welding , because it governs the amount of
or force which causes the change of shape is heat that will be required for proper fusion.
n removed . This property is extremely valuable, Conductivity of the metal , to a certain extent ,
of because it would be highly undesirable to have a determines the type of jig to be used to control
s, part permanently distorted after an applied load expansion and contraction . In aircraft, electrical
ed was removed . Each metal has a point known as conductivity must also be considered in conjunc
m the ELASTIC LIMIT beyond which it cannot be tion with bonding , to eliminate radio interfer
ed
loaded without causing permanent distortion . ence . Metals vary in their capacity to conduct
be When metal is loaded beyond its elastic limit and heat . Copper , for instance, has a relatively high
ly permanent distortion does result, it is said to rate of heat conductivity and is a good electrical
have been STRAINED . In aircraft construction, conductor .
29
Contraction and Expansion apart . Tensile strength is measured in pounds per

square inch ( psi) and is calculated by dividing
Contraction and expansion are reactions the load , in pounds required to pull the material
produced in metals as the result of heating or apart, by its cross -sectional area , in square
cooling . A high degree of heat applied to a metal inches. Metal being pulled is under tension .
will cause it to expand or become larger. Cooling COMPRESSION . - Compression is the
hot metal will shrink or contract it . Contraction opposite of tension . The compressive strength of
and expansion affect the design of welding jigs , a material is its resistance to a crushing force ,
castings , and tolerances necessary for hot-rolled which is the opposite of tensile strength.
material . Compressive strength is also measured in psi .
SHEAR . - Shear is the tendency on the part of
QUALITIES OF METALS parallel members to slide in opposite directions.
It is like placing a cord or thread between the
The selection of proper materials is a primary blades of a pair of scissors. In fact, that is how
consideration in the development of an airframe shears got their name. When a piece of metal is
and in the proper maintenance and repair of being cut with shears, the material is subject ( as
aircraft. Keeping in mind the general properties it comes in contact with the cutting edges ) to
of metals, it is now possible to consider the shear. The shear strength is the shear force in
specific requirements which metals must meet to pounds per square inch at which a material fails.
be suitable for aircraft purposes. It is the load divided by the shear area .
Strength , weight, and reliability - these three BENDING . - Bending may be described as the
factors determine the requirements to be met by deflection or curving of a member due to forces
any material used in airframe construction and acting upon it . The bending strength of material
repair. Airframes must be strong and also as light is the resistance it offers to deflecting forces.
in weight as possible. There are very definite TORSION . - Torsion is a twisting force. Such
limits to which increases in strength can be action would occur in a member fixed at one
accompanied by increase in weight . An aircraft end and twisted at the other. The torsional
so heavy that it could not support more than a strength of material is its resistance to twisting.
few hundred pounds of additional weight would
be of little use in this age . All metals, in addition Weight
to having a good strength /weight ratio , must be
>
thoroughly reliable , thus minimizing the pos The relationship between the strength of a
sibility of dangerous and unexpected failures. In material and its weight per cubic inch, expressed
addition to these general properties, the material as a ratio , is known as the STRENGTH /
selected for definite application must possess WEIGHT RATIO . This ratio forms the basis of
specific qualities suitable for the purpose . comparing the desirability of various materials
In determining the most suitable material for for use in airframe construction and repair.
a particular aircraft construction or repair job , Neither strength nor weight alone can be used as
the following qualities must be considered . a means of true comparison . In some applica
tions, such as the skin of monocoque structures
Strength (ch . 4) , thickness is more important than
strength ; and in this instance , the material with
The material must possess the strength the lightest weight for a given thickness or gage
required by the demands of dimensions, weight , is best . Thickness or bulk is necessary to prevent
and use . There are five basic stresses which buckling or damage caused by careless handling.
metals may be required to withstand . These are
tension, compression, shear, bending , and Corrosive Properties
torsion . Each is examined separately in the
following paragraphs. Corrosion is the eating away or pitting of the
TENSION . - The tensile strength of a material surface of the internal structure of metals.
is its resistance to a force which tends to pull it Because of the thin sections and the safety
30
Chapter 3 -AIRCRAFT MATERIALS
factors used in aircraft design and construction , failure . Resistance to this condition is known as
it would be dangerous to select a material shock and fatigue resistance . It is essential that
subject to severe corrosion if it were not possible materials used for critical parts be resistant to
to reduce or eliminate the hazard. Corrosion can these stresses .
be reduced or prevented by using better grades The preceding discussion of the properties
of base metals ; coating the surfaces with a thin and qualities of metals is intended to show why
coating of paint , tin , chromium , or cadmium ; or the AMS must know which traits in metals are
by an electrochemical process, called anodizing . desirable and which are undesirable to do certain
Corrosion and its control is discussed at length jobs. The more one knows about a given
in chapter 11 . material, the better able he is to handle it
intelligently in airframe repair.
Working Properties
METAL WORKING PROCESSES
Another significant factor to consider in the
selection of metals for aircraft maintenance and When metal is not cast in a desired manner , it
repair is the ability of material to be formed , is formed into special shapes by mechanical
bent , or machined to required shapes . The working processes. Several factors must be
hardening of metals by cold -working or forming considered when determining whether a desired
is termed WORK HARDENING . If a piece of shape is to be cast or formed by mechanical
metal is formed (shaped or bent ) while cold , it is working. If the shape is very complicated ,
said to be cold-worked . Practically all the work casting will be necessary in order to avoid
an AMS does on metal is cold-work . While this is expensive machining of mechanically formed
convenient , it causes the metal to become harder parts. On the other hand , if strength and quality
and more brittle . of material are the prime factors in a given part ,
If the metal is cold -worked too much that is, a casting will be unsatisfactory. For this reason ,
if it is bent back and forth or hammered at the steel castings are seldom used in aircraft work.
2 same place too often ), it will crack or break . There are three basic methods of metalwork
.) Usually , the more malleable and ductile a metal ing ; namely , hot-working, cold -working, and
is, the more cold -working it can withstand . extruding . The process chosen for a particular
application depends upon the metal involved
Joining Properties and the part required , although in some in
stances one might employ both hot and cold
a Joining metals structurally by welding, working methods in making a single part.
d brazing, or soldering, or by such mechanical
17 means as riveting or bolting, is a tremendous Hot-Working
of help in design and fabrication . When all other
Is properties are equal , material that can be welded Almost all steel is hot-worked from the ingot
I. has the advantage . into some form from which it is either hot- or
as cold-worked to the finished shaped . When an
a Shock and Fatigue Properties ingot is stripped from its mold , its surface is
es solid, but the interior is still molten. The ingot is
in Aircraft metals are subject to both shock and then placed in a soaking pit which retards loss
th fatigue (vibrational) stresses. Fatigue occurs in of heat , and the molten interior gradually
ge materials which are exposed to frequent solidifies . After soaking, the temperature is
nt reversals of loading or repeatedly applied loads, equalized throughout the ingot , which is then
g. if the fatigue limit is reached or exceeded . reduced to intermediate size by rolling, making
Repeated vibration or bending will ultimately it more readily handled.
cause a minute crack to occur at the weakest The rolled shape is called a bloom when its
point . As vibration or bending continues , the sectional dimensions are 6 x 6 inches or larger,
he crack lengthens until complete failure of the and approximately square . The section is called
1s. part results. This is termed shock and fatigue a billet when it is approximately square and less
ty
31
than 6 x 6 inches. Rectangular sections which Cold -Working

have width greater than twice the thickness are
called slabs. The slab is the intermediate shape Cold-working applies to mechanical working
from which sheets are rolled . performed at temperatures below the critical
HOT - ROLLING . - Blooms, billets, or slabs
> range and results in a strain hardening of the
are heated above the critical range and rolled metal . In fact, it becomes so hard that it is
into a variety of shapes of uniform cross section. difficult to continue the forming process with
The more common of these rolled shapes are out softening the metal by annealing.
sheet , bar, channels , angles , I -beams, and the Since the errors attending shrinkage are
like. In aircraft work , sheet , bar , and rods are eliminated in cold working, a much more
the most commonly used items that are rolled compact and better metal is obtained . The
from steel . As discussed later in this chapter, strength and hardness , as well as the elastic limit ,
hot-rolled materials are frequently finished by are increased , but the ductility decreases. Since
cold-rolling or drawing to obtain accurate finish this makes the metal more brittle, it must be
dimensions and a bright, smooth surface. heated from time to time during certain opera
FORGING . -Complicated sections which can tions to remove the undesirable effects of the
not be rolled , or sections of which only a small working.
quantity is required , are usually forged. Forging While there are several cold -working
of steel is a mechanical working of the metal processes, the two with which the AMS is
above the critical range to shape the metal as principally concerned are cold -rolling and cold
desired . Forging is done either by pressing or drawing . These processes give the metals
hammering the heated steel until the desired desirable qualities which cannot be obtained by
shape is obtained . hot-working
Pressing is used when the parts to be forged COLD-ROLLING. -Cold-rolling usually refers
are large and heavy , and this process also to the working of metal at room temperature. In
replaces hammering where high -grade steel is this operation , the materials that have been
required . Since a press is slow acting , its force is hot-rolled to approximate sizes are pickled to
uniformly transmitted to the center of the removed any scale , after which they are passed
section , thus affecting the interior grain struc through chilled finished rolls. This gives a
ture as well as the exterior to give the best smooth surface and also brings the pieces to
possible structure throughout. accurate dimensions. The principal forms of
Hammering can be used only on relatively cold -rolled stocks are sheets, bars, and rods.
small pieces. Since hammering transmits its force COLD - DRAWING . - Cold -drawing is used in
almost instantly , its effect is limited to a small making seamless tubing, wire , streamlined tie
depth . Thus , it is necessary to use a very heavy rods, and other forms of stock . Wire is made
hammer or to subject the part to repeated blows from hot-rolled rods of various diameters . These
to insure complete working of the section. If the rods are pickled in acid to remove scale , dipped
force applied is too weak to reach the center, in lime water , and then dried in a steam room
the finished forging surface will be concave. If where they remain until ready for drawing. The
the center is properly worked , the surface will
>
lime coating adhering to the metal serves as a
be convex or bulged. The advantage of hammer
lubricant during the drawing operation. Figure
ing is that the operator has control over the 3-1 illustrates the drawing of rod , tubing, and
amount of pressure applied and the finishing wire .
temperature, and is able to produce parts of the The size of the rod used for drawing depends
highest grade . upon the diameter wanted in the finished wire .
This type of forging is usually referred to as To reduce the rod to the desired wire size , it is
smith forging and is used extensively where only drawn cold through a die. One end of the rod is
a small number of parts are needed . Consider filed or hammered to a point and slipped
able machining and material are saved when a through the die opening, where it is gripped by
part is smith forged to approximately the the jaws of the draw , then pulled through the
finished shape . die . This series of operations is done by a
32
mechanism known as the drawbench , as shown and more resistant to impact . Heat treating can
in figure 3-1 . also make a metal softer and more ductile . No
In order to reduce the rod gradually to the one heat-treating operation can produce all of
desired size, it is necessary to draw the wire these characteristics. In fact, some properties are
through successively smaller dies . Because each often improved at the expense of others. For
of these drawings reduces the ductility of the example , in being hardened , a metal may
wire, it must be annealed from time to time become brittle .
before further drawings can be accomplished. All of the heat-treating processes are similar in
Although cold -working reduces the ductility, it that they involve three steps -heating the metal
increases the tensile strength of the wire to a specific temperature , holding or soaking at
enormously. the specified temperature for a definite period ,
In making seamless steel aircraft tubing, the and cooling. They differ, however , in the
tubing is cold -drawn through a ring-shaped die temperatures to which the metal is heated , the
with a mandrel or metal bar inside the tubing to time at temperature , the rate at which it is
support it while the drawing operations are cooled , and , of course , in the final result .
being performed. This forces the metal to flow The most common forms of heat treatment
between the die and the mandrel and affords a for ferrous metals (metals containing an iron
means of controlling the wall thickness and the base) are hardening, tempering, normalizing,
inside and outside diameters. annealing, and casehardening. Most nonferrous
metals (aluminum , magnesium, titanium , copper
Extruding etc. ) can be annealed and many of them can be
hardened by heat treatment. An AMS should
The extrusion process involves the forcing of have a general understanding of the following
metal through an opening in a die , thus causing heat-treating terms , definitions, and processes.
the metal to take the shape of the die opening . ANNEALING is a heat -treating operation in
Some metals such as lead, tin , and aluminum which a metal is heated to a temperature above
may be extruded cold ; but generally, metals are its recrystallization point and is then cooled
heated before the operation is begun . slowly . Its purpose may be to induce softness,
The principal advantage of the extrusion alter ductility , or refine the grain size of the
process is in its flexibility . Aluminum , because metal . During annealing, the metal is usually
of its workability and other favorable properties, cooled in a furnace, or is packed in insulating
can be economically extruded to more intricate material to retard cooling.
shapes and larger sizes than is practicable with CASEHARDENING is a heat-treating opera
many other metals . Extruded shapes are tion in which the surface of the metal is made
produced in very simple as well as extremely hard and wear resistant while the interior
complex sections. remains relatively soft and tough . In this opera
A cylinder of aluminum , for instance , is tion , the surface of the metal is altered in
heated to 750° to 850° F and is then forced composition by adding carbon , nitrogen , or a
through the opening of aa die by a hydraulic ram. combination of both .
Many structural parts , such as stringers, are CRITICAL TEMPERATURE RANGE is the
formed by the extrusion process. temperature at which a ferrous metal undergoes
a change in internal structure while being heated
HEAT TREATMENT or cooled (also called transformation range .)
NORMALIZING is a heat -treating operation
Heat treatment is a series of operations involving the heating of a ferrous metal above its
involving the controlled heating and cooling of a critical temperature range and cooling it in still
metal in its solid state . Heat treating is for the air for the purpose of removing stresses .
purpose of obtaining or restoring certain desired PRECIPITATION HEAT TREATMENT is an
characteristics or conditions so that the metal aging treatment for nonferrous alloys, usually
will be more suitable for a specific use . By heat performed at room or slightly elevated tempera
treating, a metal may be made harder, stronger, tures. Certain aluminum alloys are given this
33
HOT ROLLED DRAWING JAW

ROD DRAWN ROD
STEEL DIE 25 % TO 45 % REDUCTION

FOR EACH DRAW
MANDREL ROD DIE TUBING DRAW HEAD
SHORT MANDREL
DIE WIRE
DIE HEAD JAWS
DRAW HEAD
L
ROD
AM.227
Figure 3-1. - Cold -drawing operations for rod, tubing, and wire.
34
treatment following the solution heat treatment . but by adding small amounts of other elements
QUENCHING is the cooling of a metal from a such as copper , manganese , magnesium , zinc ,
relatively high temperature by immersing it in a and the like, its strength can be increased many
cooling medium . The cooling medium may be times . Aluminum containing such other
water , oil , or air . elements purposely added during manufacture is
RECRYSTALIZATION POINT is the called an aluminum alloy .
temperature at which the grains in a metal In addition to increasing the strength , alloying
recrystalize or re -form into very small crystals. may change the heat-resistant qualities of a
SOAKING refers to holding a metal at a metal, its corrosion resistance , electrical
required temperature for a specified time to conductivity , or magnetic properties. It may
obtain an even temperature throughout the cause an increase or decrease in the degree to
section . which hardening occurs after cold-working.
SOLUTION HEAT TREATMENT is a heat Alloying may also make possible an increase or
treatment for nonferrous alloys in which the decrease in strength and hardness by heat
alloy is heated to a specified temperature (below treatment . Alloys are , therefore , of great impor
the melting point ) , is held at this temperature tance to the aircraft industry in providing
for the required length of time , and is then materials with properties that pure metals alone
quenched . The purpose of this treatment is to do not possess .
cause as much of the alloying constituents as
possible to go into solid solution and to retain FERROUS AIRCRAFT METALS
this condition by quenching.
TEMPER DESIGNATION is a term which
A wide variety of materials is required in the
refers specifically to non ferrous alloys. It repair of aircraft . This is a result of the varying
consists of letters or letters and numbers which needs with respect to strength , weight,
show the condition of the alloy and the heat durability , and resistance to deterioration of
treatment it has had . The temper designation is specific structures or parts. In addition , the
usually printed on the surface of the metal .
particular shape or form of the material plays an
TEMPERING is a heat-treating operation in important role . In selecting materials for aircraft
which hardened steel is partially annealed and repair , these factors plus many others are
the desired mechanical properties induced by considered in relation to their mechanical and
reheating the metal to a temperature below its physical properties . Among the common mate
critical point .
rials used are ferrous metals . The term FER
ROUS applies to the group of metals having iron
ALLOYING OF METALS as their principal constituent .
A substance that possesses metallic properties Identification
and is composed of two or more chemical
elements , of which at least one is a metal, is If carbon is added to iron , in percentages
called an ALLOY . The metal present in the alloy ranging up to approximately 1.00 percent , the
in the largest proportion is called the BASE product will be vastly superior to iron alone and
METAL. All other metals and /or elements added is classified as carbon steel . Carbon steel forms
to the alloy are called ALLOYING ELEMENTS. the base of those alloy steels produced by
The metals are dissolved in each other while combining carbon with other elements known to
molten , and they do not separate into layers improve the properties of steel. A base metal
when the solution solidifies. Practically all the (such as iron ) to which small quantities of other
metals used in aircraft are made up of a number metals have been added is called an ALLOY .
of alloying elements. The addition of other metals is to change or
Alloying elements , either in small or in large improve the chemical or physical properties of
amounts, may result in a marked change in the the base metal .
properties of the base metal . For example, pure SAE NUMERICAL INDEX. -The steel
aluminum is a relatively soft and weak metal , classification of the Society of Automotive
35
Engineers (SAE ) is used in specifications for all this test the piece of iron or steel is held against
highgrade steels used in automotive and aircraft a revolving stone and the metal is identified by
construction . A numerical index system the sparks thrown off. Each ferrous metal has its
identifies the composition of SAE steels . own peculiar spark characteristics. The spark
Each SAE number consists of a group of streams vary from a few tiny shafts to a shower
digits , the first of which represents the type of of sparks several feet in length. Few nonferrous
steel ; the second , the percentage of the principal metals give off sparks when touched to a
alloying element ; and usually the last two or grinding stone. Therefore, these metals cannot
three digits the percentage, in hundredths of 1 be successfully identified by the spark test .
percent , of carbon in the alloy. For example , the Wrought iron produces long shafts that are
SAE number 4150 indicates a molybdenum steel dull red colored as they leave the stone and end
containing 1 percent molybdenum and 50 up a white color. Cast iron sparks are red as they
hundredths of 1 percent of carbon. Refer to the leave the stone and turn to a straw color.
SAE numerical index shown in table 3-1 to see Low - carbon steels give off long straight shafts
how the various types of steel are classified into having a few white sprigs. As the carbon content
four -digit classificaticn numbers . of the steel increases , the number of sprigs along
each shaft increases and the stream becomes
Table 3.1 . - SAE numerical index . whiter in color. Nickel steel causes the spark
stream to contain small white blocks of light
within the main burst .
Type of steel Classification

Types, Characteristics, and
Carbon 1xxx Uses of Alloyed Steels
Nickel 2xxx
Nickel- chromium 3xxx While steel of the plain carbon type remains
Molybdenum 4xxx the principal product of the steel mills, so-called
Chromium 5xxx alloy or special steels are being turned out in
Chromium - vanadium 6xxx ever increasing tonnage . Let us now consider
Tungsten 7xxx those alloyed steels and their uses in aircraft.
Silicon - manganese 9xxx CARBON STEELS. - Steel containing carbon
in percentages ranging from 0.10 to 0.30 percent
are classed as LOW- CARBON STEEL .
The equivalent SAE numbers range from 1010
to 1030. Steels of this grade are used for making
such items as safety wire, certain nuts, cable
HARDNESS TESTING METHODS. bushings, and threaded rod ends. Low - carbon
Hardness testing is a factor in the determination steel in sheet form is used for secondary
of the results of heat treatment as well as the structural parts and clamps , and in tubular form
condition of the metal before heat treatment . for moderately stressed structural parts.
There are two commonly used methods of Steels containing carbon in percentages
hardness testing , the BRINELL and the ROCK ranging from 0.30 to 0.50 percent are classed as
WELL tests. These tests require the use of MEDIUM -CARBON STEEL . This steel is
specific machines and are not covered in this especially adaptable for machining or forging
training manual. (A knowledge of hardness and where surface hardness is desirable . Certain
testing procedures is a requirement for E-6 .) An rod ends and light forgings are made from SAE
additional somewhat indirect method (SPARK 1035 steel.
TESTING ) is used in identifying ferrous metals, Steel containing carbon in percentages ranging
this identification , in turn , giving some from 0.50 to 1.05 percent are classed as HIGH
indication of the hardness of the metal . CARBON STEEL . The addition of other
Spark testing is a common means of identify elements in varying quantities adds to the
ing ferrous metals which have become mixed. In hardness of this steel . In the fully heat- treated
36
condition it is very hard and will withstand high and about 1.00 percent chromium . When heat
shear and wear and have little deformation . It treated , they have strength , toughness , and
has limited use in aircraft . SAE 1095 in sheet resistance to wear and fatigue. A special grade
form is used for making flat springs, and in wire of this steel in sheet form can be cold - formed
form for making coil springs. into intricate shapes. It can be folded and
NICKEL STEELS . -The various nickel steels flattened without signs of breaking or failure .
are produced by combining nickel with carbon SAE 6150 is used for making springs; and
steel . Steels containing from 3 to 3.75 percent chrome-vanadium with high-carbon content ,
nickel are commonly used . Nickel increases the SAE 6195 , is used for ball and roller bearings.
hardness , tensile strength , and elastic limit of CHROME - MOLYBDENUM STEELS.
steel without appreciably decreasing the Molybdenum in small percentages is used in
ductility . It also intensifies the hardening effect combination with chromium to form chrome
of heat -treatment . SAE 2330 steel is used molybdenum steel which has various uses in
extensively for aircraft parts such as bolts, aircraft. Molybdenum is a strong alloying ele
terminals, keys, clevises, and pins . ment , only 0.15 to 0.25 percent being used in
CHROMIUM STEELS. - Chromium steels are the chrome-molybdenum steels ; the chromium
high in hardness , strength, and corrosion content varies from 0.80 to 1.10 percent .
resistant properties . SAE 51335 is particularly Molybdenum raises the ultimate strength of steel
adaptable for heat-treated forgings which require without affecting ductility or workability . Moly
greater toughness and strength than may be bdenum steels are tough , wear-resistant , and
obtained in plain carbon steel . It is used for such harden throughout from heat treatment. They
articles as the balls and rollers of antifriction are especially adaptable for welding, and for this
bearings. reason are used principally for welded structural
CHROME -NICKLE OR ' STAINLESS parts and assemblies. SAE 4130 is used for parts
STEELS . - These are corrosion -resisting metals. such as engine mounts , nuts , bolts, gear struc
The anticorrosive degree is determined by the tures, support brackets for accessories and other
surface condition of the metal as well as by the structural parts.
composition, temperature , and concentration of The progress of jet propulsion in the field of
the corrosive agent. naval aviation has been aided by the continuous
The principal part of stainless steel is research in high -temperature metallurgy. This
chromium , to which nickel may or may not be research has brought forth alloys to withstand
added . The corrosion-resisting steel most often the high temperatures and velocities encount
used in aircraft construction is known as 18-8 ered in jet power units. These alloys are chemic
steel because of its content of 18 percent ally similar to the previously mentioned steels,
chromium and 8 percent nickel . One of the but may also contain cobalt , copper, and
>
distinctive features of 18-8 steel is that its columbium in varied amounts as alloying ele
strength may be increased by cold -working . ments .
Stainless steel may be rolled , drawn , bent , or
formed to any shape . Because these steels NONFERROUS AIRCRAFT METALS
expand about 50 percent more than mild steel
and conduct heat only about 40 percent as The term NONFERROUS refers to all metals
rapidly , they are more difficult to weld . Stain which have elements other than iron as their
less steel, with but a slight variation in its principal constituent . This group includes alumi
chemical composition , can be used for almost num , titanium , copper , and magnesium and their
any part of an aircraft. Some of its more alloys; and in addition , such alloy metals as
>
common applications are in the fabrication of monel and babbitt .

exhaust collectors, stacks and manifolds, struc
tural and machined parts , springs, castings , and Aluminum and Aluminum Alloys
tie rods and cables .
CHROME-VANADIUM STEELS.- These are Commercially pure aluminum is a white ,
made of approximately 0.18 percent vanadium lustrous metal , light in weight and corrosion
37
resistant. Aluminum combined with various per The various types of aluminum may be
centages of other metals (generally copper, divided into two classes -CASTING ALLOYS
manganese , magnesium , and chromium) form (those suitable for casting in sand, permanent
the alloys which are used in aircraft construc mold , and die castings) and the WROUGHT
tion . Aluminum alloys in which the principal ALLOYS ( those which may be shaped by
alloying ingredients are either manganese , mag rolling, drawing, or forging ). Of the two , the
nesium , or chromium , or magnesium and silicon wrought alloys are the most widely used in
show little attack in corrosive environments. On aircraft construction , being used for stringers ,
>
the other hand, those alloys in which substantial bulkheads , skin , rivets, and extruded sections.
percentages of copper are used are more sus Casting alloys are not so extensively used in
ceptible to corrosive action . The total percent aircraft.
age of alloying elements is seldom more than 6 WROUGHT ALLOYS . -Wrought alloys are
or 7 percent in the wrought aluminum alloys. divided into two classes - nonheat treatable and
heat treatable . In the nonheat-treatable class,
TYPES , CHARACTERISTICS, AND USES.
Aluminum is one of the most widely used metals strain hardening (cold -working) is the only
in modern aircraft construction . It is vital to the means of increasing the tensile strength . Heat
aviation industry because of its high strength / treatable alloys may be hardened by heat treat
weight ratio , its corrosion -resisting qualities , and ment , by cold -working, or by the application of
both processes.
its comparative ease of fabrication . The out
Aluminum products are identified by a
standing characteristic of aluminum is its light universally used designation system. Under this
weight. In color , aluminum resembles silver
arrangement, wrought aluminum and wrought
although its possesses a characteristic bluish
tinge of its own . Commercially pure aluminum aluminum alloys are designated by a four-digit
index system .
melts at the comparatively low temperature of The first digit of the designation indicates the
1,220° F . It is nonmagnetic and is an excellent major alloying element or alloy group , as shown
conductor of electricity . in table 3-2. Thus lxxx indicates aluminum of
Commercially pure aluminum has a tensile 99.00 percent or greater , 2xxx indicates an
strength of about 13,000 psi, but by rolling or aluminum alloy in which copper is the major
other cold -working processes its strength may be alloying element , 3xxx indicates an aluminum
approximately doubled . By alloying with other alloy with manganese as the major alloying
metals, together with the use of heat-treating element, etc. Although most aluminum alloys
processes, the tensile strength may be raised to
as high as 96,000 psi , or to well within the
>
strength range of structural steel. Table 3-2 . - Designations for aluminum

alloy groups.
Aluminum alloy material, although strong , is
easily worked , for it is very malleable and
ductile. It may be rolled into sheets as thin as
0.0017 inch or drawn into wire 0.004 inch in
diameter . Most aluminum alloy sheet stock used
in aircraft construction ranges from 0.016 to Aluminum - 99.00 percent minimum
and greater .. 1xxx
0.096 inch in thickness; however, some of the Aluminum alloys, grouped by major
larger aircraft use sheet stock which may be as alloying element:
thick as 0.356 inch .
Copper . . 2XXX
One disadvantage of aluminum alloy is the Manganese . . . 3xxx
difficulty of making reliable soldered joints. Silicon . . . 4xxx
Oxidation of the surface of the heated metal Magnesium . O . C . 5xxx
prevents soft solder from adhering to the Magnesium and silicon . . 6xxx
material ; therefore, to produce good joints of Zinc . 7xxx
aluminum alloy, a riveting process is used . Some Other elements 8xxx
aluminum alloys are also successfully welded .
38
contain several alloying elements , only one structural purposes in aircraft in preference to
group ( 6xxx) designates more than one alloying the nonheat-treatable alloys. Heat-treatable
element . alloys commonly used in aircraft construction
In the lxxx group the second digit in the (in order of increasing strength ) are 6061 , 6062 ,
designation indicates modifications in impurity 6063 , 2017 , 2024, 2014 , 7075 , and 7178 .
limits. If the second digit is zero , it indicates Alloys 6061 , 6062 , and 6063 are sometimes
that there is no special control on individual used for oxygen and hydraulic lines and in some
impurities. The last two of the four digits applications as extrusions and sheet metal .
indicate the minimum aluminum percentage .
Alloy 2017 is used for rivets, stressed -skin
Thus , alloy 1030 indicates 99.30 percent covering , and other structural members.
aluminum without special control on impurities.
Alloys 1130, 1230, 1330, etc. , indicate the same Alloy 2024 is used for airfoil covering and
fittings. It may be used wherever 2017 is
aluminum purity with special control on one or specified , since it is stronger.
more impurities. Likewise , 1075 , 1175 , 1275 , Alloy 2014 is used for extruded shapes and
etc. , indicate 99.75 percent aluminum . forgings. This alloy is similar to 2017 and 2024
In the 2xxx through 8xxx groups , the second in that it contains a high percentage of copper.
digit indicates alloy modifications. If the second It is used where more strength is required than
digit in the designation is zero , it indicates the that obtainable from 2017 or 2024 .
original alloy , while numbers 1 through 9 ,
assigned consecutively , indicate alloy modifica Alloy 7178 is used where highest strength is
tions. The last two of the four digits have no necessary . Alloy 7178 contains a small amount
special significance, but serve only to identify of chromium as a stabilizing agent as does alloy
the different alloys in the group . 7075 .
The temper designation follows the alloy Nonheat-treatable alloys used in aircraft
designation and shows the actual condition of construction are 1100, 3003 , and 5052. These
the metal . It is always separated from the alloy alloys do not respond to any heat treatment
designation by a dash , as shown in Table 3-3. other than a softening, annealing effect. They
The letter F following the alloy designation may be hardened only by cold -working.
indicates the “ as fabricated ” condition , in which
> Alloy 1100 is used where strength is not an
no effort has been made to control the mechani important factor but where weight, economy ,
cal properties of the metal . and corrosion resistance are desirable . This alloy
The letter O indicates dead soft , or annealed , is used for fuel tanks , fairings, oil tanks, and for
>
condition . the repair of wingtips and tanks .

The letter W indicates solution heat treated . Alloy 3003 is similar to 1100 and is generally
Solution heat treatment consists of heating the used for the same purposes . It contains a small
metal to a high temperature followed by a rapid percentage of manganese and is stronger and
quench in cold water. This is an unstable harder than 1100 , but retains enough work
temper, applicable only to those alloys which ability that it is usually preferred over 1100 in
spontaneously age at room temperature . Alloy most applications.
7075 may be ordered in the W condition. Alloy 5052 is used for fuel lines, hydraulic
The letter H indicates strain hardened ; that is, lines , fuel tanks, and wingtips. Substantially
cold-worked , hand -drawn , or rolled . Additional higher strengths without too much sacrifice of
digits are added to the H to indicate the degree workability can be obtained in 5052. It is
of strain hardening. (See table 3-3 .) Alloys in therefore preferred over 1100 and 3003 in many
this group cannot be strengthened by heat applications. Table 3-4 shows the nominal
treatment , hence the term nonheat treatable . chemical compositions for the wrought alloys.
The letter T indicates fully heat treated . Alclad is the name given to standard
Digits are added to the T to indicate certain aluminum alloys which have been coated on
variations in treatment . both sides with a thin layer of pure aluminum .
Greater strength is obtainable in the heat Alclad has very good corrosion - resisting qualities
treatable alloys . Therefore, they are used for and is used exclusively for exterior surfaces of
39
Table 3-3. - Temper designations for aluminum alloys.
Designation Condition indicated Example
-F... As fabricated 3003 - F
-O Fully annealed .. 6061-0
-W Unstable following solution heat

treatment. 7075 - W
-H Strain hardened ( cold worked )
-HI , Strain hardened only 3003 - H12

plus one or more digits.
-H2, Strain hardened and then partially annealed . 3003 - H24
-H3, Strain hardened and then stabilized 5052 - H36
-T . Heat treated
-T3 . o Solution heat treated and then cold worked. 2024 - T3
-T4 ...
. . Solution heat treated ... 2024-14
-T5 ... Artificially aged only 6063 - T5
-T6 . Solution heat treated and then artificially 7075 - T6

aged .
-T7 . . Solution heat treated and then stabilized to 7075 - T7

control growth and distortion .
-18 .. Solution heat treated, cold worked, and then 2024- T86
artificially aged.
-T9 . Solution heat treated, artificially aged, and 6061 - T91

then cold worked.
-TIQ ... Artificially aged and then cold worked . 2014- T10
NOTE : The -T designations above may have one or more digits added to denote certain variations of
the basic heat treatments described .
40
Table 3-4 . - Chemical composition of aluminum alloys.

Alloy Alloying elements in percent. Aluminum and normal
impurities constitute remainder.
Silicon Copper Manganese Magnesium Chromium Zinc
3003 0.6 0.2 1.2 0.1

2014 0.8 4.5 0.8 0.4 0.1 0.25
2017 0.8 4.0 0.5 0.5 0.1 0.25
2117 2.5 0.3
2024 0.5 4.5 0.6 1.5 0.1 0.25
5052 0.45 0.1 0.1 2.5 0.25 0.1
-
5056 0.1 5.2 0.1
6061 0.6 0.25 0.15 1.0 0.25 0.25
6062 0.6 0.25 0.15 1.0 0.06 0.25
6063 0.4 0.1 0.1 0.7 0.1 0.25
7075 0.5 1.6 0.3 2.5 0.3 5.6
7178 2.0 0.3 2.7 0.3 6.8
aircraft. Alclad sheet is available in all tempers Aluminum alloy castings are produced by one
of 2014, 2017 , 7075 , and 7178 .
> of three basic methods - sand mold , permanent
CASTING ALLOYS . - Aluminum casting mold , and die cast . In casting aluminum , it must
alloys , like wrought alloys , are divided into two be remembered that in most cases different
groups. In one, the physical properties of the types of alloys must be used for different types
alloys are determined by the elements added and of castings. Sand castings and die castings
cannot be changed after the metal is cast . In the require different types than those used in
other, the elements added make it possible to permanent molds .
heat treat the casting to produce desired SHOP CHARACTERISTICS OF ALUMINUM
physical properties . ALLOYS . - Aluminum is one of the most readily
-
The casting alloys are identified by a letter workable of all the common commercial metals.
preceding the alloy number. This is exactly It can be fabricated readily into a variety of
opposite from the case of wrought alloys in shapes by any conventional method ; however,
which the letters follow the number . When a formability varies a great deal with the alloy and
letter precedes a number, it indicates a slight temper.
variation in the composition of the original In general, the aircraft manufacturers form
alloy. This variation in composition is made the heat-treatable alloys in the - or -T4 condi
simply to impart some desirable quality . In tion before they have reached their full strength.
casting alloy 214, for example, the addition of They are subsequently heat treated or aged to
zinc , to increase its pouring qualities is the maximum strength (-T6) condition before
designated by the letter A in front of the installation in aircraft. By this combination of
number, thus creating the designation A214 . processes, the advantage of forming in a soft
When castings have been heat treated , the condition is obtained without sacrificing the
heat treatment and the composition of the maximum obtainable strength /weight ratio .
casting are indicated by the letter T and an Aluminum is one of the most readily weldable
alloying number. An example of this is the sand of all metals . The nonheat-treatable alloys can
casting alloy 355 which has several different be welded by all methods , and the heat-treatable
compositions and tempers and is designated by alloys can be successfully spot welded . The
355 - T6 , 355- T51, and A355 - T51. melting point for pure aluminum is 1,220 ° F,
41
while various aluminum alloys melt at slightly of glass, moistened titanium will leave a dark
lower temperatures. Aluminum products do not line similar in appearance to a pencil mark .
show any color changes on being heated , even
up to the melting point. Riveting is the most Copper and Copper Alloys
reliable method of joining stress-carrying parts
of heat- treated aluminum alloy structures. Most commercial copper is refined to a purity
of 99.9 percent minimum copper plus silver . It is
the only reddish colored metal and is second
Titanium and Titanium Alloys only to silver in electrical conductivity . Its use as
a structural material is limited because of its
Titanium and titanium alloys are used chiefly great weight. However, some of its outstanding
for parts which require good corrosion resist characteristics, such as its high electrical and
ance , moderate strength up to 600° F, and light heat conductivity , in many cases overbalance the
weight . weight factor.
TYPES , CHARACTERISTICS, AND USES. Because it is very malleable and ductile ,
Titanium alloys are being used in quantity for copper is ideal for making wire . In aircraft ,
jet engine compressor wheels, compressor copper is used primarily for the electrical system
blades, spacer rings , housing compartments , and and for instrument tubing and bonding. It is
airframe parts such as engine pads, ducting, wing corroded by salt water but is not affected by
surfaces, firewalls, fuselage skin adjacent to the fresh water. The ultimate tensile strength of
engine outlet , and armor plate . copper varies greatly . For cast copper , the
In view of titanium's high melting tempera tensile strength is about 25,000 psi ; and when
ture , 3,300°° F,
approximately 3,300 F, its high cold-rolled or cold -drawn , its tensile strength
>
temperature properties are disappointing. The increases, ranging from 40,000 to 67,000 psi .
ultimate and yield strengths of titanium drop BRASS . -Brass is a copper alloy containing
fast above 800° F . In applications where the zinc and small amounts of aluminum , iron , lead ,
declines might be tolerated , the absorption of
>
manganese, magnesium , nickel , phosphorous,
oxygen and nitrogen from the air at temperature and tin . Brass with a zinc content of 30 to 35
above 1,000° F, makes the metal so brittle on percent is very ductile while that containing 45
long exposure that it soon becomes worthless. percent has relatively high strength . MUNTZ
Titanium has some merit for short - time METAL is a brass composed of 60 percent
exposure up to 2,000° F where strength is not copper and 40 percent zinc. It has excellent
important, as in aircraft firewalls. corrosion -resistant qualities when in contact
Sharp tools are essential in machining tech with salt water. Its strength can be increased by
niques as titanium has a tendency to resist or heat treatment. As cast , this metal has an
back away from the cutting edge of tools. It is ultimate tensile strength of 50,000 psi and can
readily welded , but the tendency of the metal to be elongated 18 percent . It is used in making
absorb oxygen , nitrogen , and hydrogen must bolts and nuts , as well as parts that come in
never be ignored. Machine welding with an inert contact with salt water. RED BRASS , some
gas atmosphere has proven most successful. times termed bronze because of its tin content ,
Both commercially pure and alloy titanium is used in fuel and oil line fittings. This metal has
can absorb large amounts of cold -work without good casting and finishing properties and
cracking. Practically anything that can be deep machines freely .
drawn in low - carbon steel can be duplicated in BRONZES . -Bronzes are copper alloys
commercially pure titanium , although the containing tin. The true bronzes have up to 25
titanium may require more intermediate anneals. percent tin , but those below 11 percent are most
IDENTIFICATION OF TITANIUM. useful, especially for such items as tube fittings
Titanium metal, pure or alloyed , is easily in aircraft.
identified. When touched with a grinding wheel , Among the copper alloys are the copper
it makes white spark traces which end in aluminum alloys , of which the aluminum
brilliant white bursts . When rubbed with a piece bronzes rank very high in aircraft usage. They
42
would find greater usefulness in structures if it tensile strength rising from 70,000 psi in the
were not for their strength / weight ratio as annealed state to 200,000 psi in the heat- treated
compared with alloy steels. Wrought aluminum state . The resistance of beryllium copper to
bronzes are almost as strong and ductile as fatigue and wear makes it suitable for dia
medium-carbon steel and possess a high degree phrams , precision bearings and bushings , ball
of resistance to corrosion by air , salt water , and cages , spring washers , and nonsparking tools .
chemicals. They are readily forged , hot- or
cold -rolled , and many react to heat treatment. Monel
These copper-base alloys contain up to 16
percent of aluminum ( usually 5 to 11 percent) Monel , the leading high -nickel alloy, combines
to which other metals such as iron , nickel, or the properties of high strength and excellent
manganese may be added . Aluminum bronzes corrosion resistance . This metal consists of 67
have good tearing qualities , great strength , hard percent nickel , 30 percent copper, 1.4 percent
ness , and resistance to both shock and fatigue . iron , 1 percent manganese , and 0.15 percent
Because of these properties , they are used for carbon. It cannot be hardened by heat treat
diaphragms and gears , air pumps , condenser ment - responding only to cold-working.
bolts, and slide liners. Aluminum bronzes are Monel , adaptable to castings and hot or cold
available in rods , bars , plates , sheets , strips, and working , can be successfully welded and has
forgings. working properties similar to those of steel . It
Cast aluminum bronzes , using about 89 per has a tensile strength of 65,000 psi which , by
cent copper , 9 percent aluminum , and 2 percent means of cold -working, may be increased to
of other elements , have high strength combined 160,000 psi , thus entitling this metal to
with ductility , and are resistant to corrosion , classification among the tough alloys. Monel has
shock , and fatigue . Because of these properties, been successfully used for gears and chains , for
cast aluminum bronze is used in gun mounts , operating retractable landing gears , and for
bearings , and pump parts. These alloys are useful structural parts subject to corrosion . In aircraft,
in areas exposed to salt water and corrosive monel has long been used for parts demanding
gases. both strength and high resistance to corrosion ,
Manganese bronze is an exceptionally high such as exhaust manifolds and carburetor needle
strength , tough , corrosion-resistant copper zinc valves and sleeves.
alloy containing aluminum, manganese , iron,
and occasionally nickel or tin . This metal can be K-Monel
formed , extruded, drawn , or rolled to any
desired shape. In rod form , it is generally used K-monel is a nonferrous alloy containing
for machined parts . Otherwise it is used in mainly nickel, copper, and aluminum . It is
catapults , landing gears, and brackets . produced by adding a small amount of
Silicon bronze is composed of about 95 aluminum to the monel formula. It is corrosion
percent copper, 3 percent silicon , and 2 percent resistant and capable of hardening by heat
manganese, zinc , iron , tin , and aluminum .
treatment . K-monel has been successfully used
Although not a bronze in the true sense of the for gears, chains, and structural members in
word because of its small tin content , silicon aircraft which are subjected to corrosive attacks.
bronze has high strength and great corrosion This alloy is nonmagnetic at all temperatures.
resistance and is used variably . K-monel can be successfully welded .
BERYLLIUM COPPER . - Beryllium copper is
one of the most successful of all the copper-base
alloys. It is a recently developed alloy containing Magnesium and Magnesium Alloys
about 97 percent copper, 2 percent beryllium ,
and sufficient nickel to increase the percentage Magnesium , the world's lightest structural
of elongation . The most valuable feature of this metal , is a silvery-white material weighing only
metal is that the physical properties can be two -thirds as much as aluminum. Magnesium
greatly stepped up by heat treatment - the does not possess sufficient strength in its pure
43
state for structural uses; but when alloyed with Magnesium alloys possess good casting charac
zinc , aluminim , and manganese , it produces an teristics. Their properties compare favorably
alloy having the highest strength /weight ratio . with those of cast aluminum . In forging, hy
TYPES , CHARACTERISTICS, AND USES. - draulic presses are ordinarily used ; although ,
Magnesium is probably more widely distributed under certain conditions , forging can be ac
in nature than any other metal . It can be complished in mechanical presses or with drop
obtained from such ores as dolomite and hammers .
magnesite, from underground brines , from waste Magnesium embodies fire hazards of an un
liquors of potash , and from sea water. With predictable nature . When in large sections , its
about 10 million pounds of magnesium in 1 high thermal conductivity makes it difficult to
cubic mile of sea water, there is no danger of a
>
ignite, and prevents its burning. It will not burn
dwindling supply. until the melting point is reached , which is
Magnesium is used extensively in the approximately 1,200° F. However, magnesium
manufacture of helicopters. Its low resistance to dust and fine chips are ignited easily . Pre
corrosion has been a factor in reducing its use in cautions must be taken to avoid this if possible,
conventional aircraft. and to extingush them immediately . An
The machining characteristics of magnesium extinguishing powder , such as powdered soap
alloys are excellent . Usually the maximum stone , clean, dry, unrusted cast iron chips, or
speeds of machine tools can be used with heavy graphite powder, should be used .
cuts and high feed rates. Power requirements for
magnesium alloys are about one-sixth of those
for mild steel . An excellent surface finish can be CAUTION : Water or any standard liquid or
produced , and in most cases grinding is not foam extinguisher causes magnesium to burn
essential. Standard machine operations can be more rapidly and may cause small explosions.
performed to tolerances of a few ten
thousandths of an inch . There is no tendency of
the metal to tear or drag .
Magnesium alloy sheets can be worked in
much the same manner as other sheet metal with
one exception - the metal must be worked while HYDRAULIC RAM
hot . The structure of magnesium is such that the
alloys work-harden rapidly at room tempera
tures. The work is usually done at temperatures RUBBER
ranging from 450° to 650° F, which is a dis PAD
advantage. However, compensations are offered
by the fact that in the ranges used , magnesium is
more easily formed than other materials. Sheets
can be sheared in much the same way as other
metals, except that a rough flaky fracture is
produced on sheets thicker than about 0.064
inch . A better edge will result on a sheet over
0.064 inch thick if it is sheared hot .
Annealed sheet can be heated to 600° F, but
hard rolled sheet should not be heated above
275 ° F. A straight bend with short radius can be
made by the GUERIN PROCESS, as shown in
> MALE DIE STATIONARY BED
figure 3-2 , or by press or leaf brakes. The Guerin
process is the most widely used method for
forming and shallow drawing, employing a
rubber pad as the femal die , which bends the AM.228
work to the shape of the male die . Figure 3-2. -Guerin process.
44
ac SUBSTITUTION AND maintenance and repair involving substitution

oly INTERCHANGEABILITY and interchangeability of aircraft structural
ny OF AIRCRAFT METALS metals . BE SURE YOU HAVE THE AERO
gh, NAUTIC TECHNICAL PUBLICATION OF THE
ac In selecting interchangeable or substitute MOST RECENT ISSUE .
гор materials for the repair and maintenance of
naval aircraft, it is of the utmost importance to
un check the appropriate aeronautic technical
its publications when specified materials are not in
t to stock nor obtainable from another source . It is INSPECTION OF METALS
urn impossible to determine that another material is
7 is as strong as the original by mere observation . When a metallic part is suspected of having a
jum There are four requirements that must be kept tiny crack or other invisible defect, it is general
Pre clearly in mind in this selection. The first and ly inspected by one of the following methods :
ible , most important of these is maintaining the the penetrant method , the magnetic particle
An original strength of the structure. The other inspection method , the radiographic ( X - ray)
оар three are maintaining contour or aerodynamic method, the eddy current method , or the
s , or smoothness, maintaining original weight if ultrasonic method .
possible or keeping added weight to a minimum , The various types and methods of penetrant
and maintaining the original corrosive -resistance inspections are suitable for locating almost any
properties of the metal . type of defect open to the surface on a variety
d or The importance of checking the specific of nonabsorbent materials such as ferrous and
burn technical publication can be appreciated by nonferrous metals, ceramics, hard rubber,
S.
understanding that different manufacturers plastic , and glass. Metals that can be magnetized
design structural members to meet various load ( ferrous metals) are usually inspected by the
requirements for specific aircraft. Structural magnetic particle method. The X-ray method
repair of these members, apparently similar in may be used for inspecting any of the foregoing
construction, will thus vary in their load carry metals. All of these methods are nondestructive
ing design with different aircraft . tests , which means they are performed on the
Structural repair instructions , including tables actual part without damage to the part.
of interchangeability and substitution for To advance to E - 4 , all AMS strikers must be
ferrous and nonferrous metals and their able to perform dye penetrant inspections, and
specifications for all types of aircraft used by to advance from E - 4 to E-5 , the AMS must be
>
.
the Navy , are normally prepared by the contrac able to interpret the results obtained by using
tor. Such instructions are usually promulgated in the penetrant method. Coverage on other
the -3 manual covering structural repair instruc methods of inspecting metals mentioned above
tions for specific model of aircraft. Similar is not included in this chapter, as proficiency in
information is also contained in NavAir 01-1A- 1 , these methods is not a requirement at this level.
General Manual for Structural Repair. The following section will provide basic
NavAir 01-1A- 1 , section III , table IV , presents
> coverage on the types and methods of penetrant
the substitution and conversion information for inspection, general inspection procedures, and
aluminum alloy sheet metal. In section IV , table > interpretation of results. Complete and detailed
IV, steel specifications are given ; table V , in
> > coverage necessary for a thorough understanding
section IV , covers aluminum specifications. of the penetrant methods of inspection is
NavAir 01-1A-9 , Aerospace Metals - General provided in NavAir 01-1A - 16 ,, Nondestructive
Data and Usage Factors , provides precise data on Inspection Methods, Technical Manual . Tests on
BED
specific metals to assist in selection , usage, and critical aircraft components require a thorough
processing for fabrication and repair. knowledge of all material included in that
Always consult these publications and the -3 section of the manual for the specific test being
aircraft manual for the specific -type aircraft conducted to insure proper testing and inter
.M.228 when confronted with a problem concerning pretation .
45
PENETRANT INSPECTIONS the defects. If the part has been in contact with
water it may be possible to heat the part slightly
Penetrant inspection is a nondestructive test to evaporate the water.
for defects open to the surface in parts made of Penetrant is then applied to all surfaces. This
any nonporous material . Penetrant inspection may be done by dipping , flow -on , brushing, or
depends for its success upon a penetrating liquid spraying. It is important that all suspect areas be
entering the surface opening and remaining in wet with penetrant . The penetrant must be
that opening, making it clearly visible for the allowed to remain on the part for a period of
operator. It calls for visual examination of the
time called the penetration (dwell ) time . This
part by the operator after it has been processed , allows the penetrant to seek and fill surface
but the visibility of the defect is increased so openings. The length of the penetration time
that it can be detected. Visibility of the
penetrating material is increased by the addition varies with the process and techniques used , the
material of which the part is made , and the
of dye which may be either one of two types of defects present .
types -visible or fluorescent.
The excess surface penetrant is removed from
The main disadvantage of penetrant inspec
the part by means of a forceful water spray . This
tion is that the defect must be open to the operation does not remove the penetrant from
surface in order to let the penetrant into the deep defects but does remove the penetrant on
defect. For this reason , if the part in question is the surface.
made of material which is magnetic, the A developer is then applied to the part before
magnetic particle inspection or X-ray is generally inspection. The function of the developer is to
recommended . It is also essential that there be blot back to the surface the penetrant that is
no contaminant within the defect which might entrapped in fissures or defects in the part . The
either prevent the penetrant from entering or developer should be allowed to remain on the
which may reduce its visibility . part for a time before inspection for defects .
The materials used in the visible dye
This elapsed time is to allow the developer to
penetrant inspection are available in aviation
bring back to the surface and magnify the traces
supply stock in the form of a complete inspec of penetrant . Some types of defects in some
tion kit . Included in the kit are the following parts may be detectable without the use of a
items : two spray cans of penetrant , dye
developer, but for consistent and positive
remover -emulsifier , and developer . For results , current instructions recommend that a
replenishment purposes, these materials are also developer always be used . A drying operation is
available as individual items . The chemicals are necessary which increases the effectiveness of
available in ordinary containers for use when the method and , depending upon the type of
dipping or brushing is desired . developer used , either dries the wet developer or
The fluorescent inspection materials and prepares the part for the application of the dry
equipment are also furnished in kit form . The developer.
complete equipment is contained in a metallic After the proper developing time has elapsed ,
carrying case. Included are the following items : the part is ready for inspection . If the penetrant
penetrant , penetrant cleaner, penetrant used has a fluorescent dye in it , the inspection
developer (both powder and suspension types), must be performed in a darkened area and under
dauber for applying powder, and a black light black light. If the penetrant used has a visible
(ultra violet ) assembly complete with power die , then inspection can be performed under
transformer. The chemicals may be replenished ordinary lighting conditions.
individually from aviation supply stock . All traces of the developer should be removed
from the part before it is returned to service .
General Inspection Procedure
First of all , the part to be inspected must be Types of Processes
clean . This includes the removal of surface dirt ,
scale, paint , and oil , as well as removing any There are two types of penetrant inspection
materials or compounds that might fill or cover processes. Type I employs the use of fluorescent
46
penetrants, and Type Il processes employ the lists the types and methods of penetrant inspec
use of visible dye penetrants. Within each type tion and their related group of materials..
there are three methods, which are referred to as
>
Group I through group III penetrants are
methods A , B , and C. Each method within a visible dye penetrants containing dyes that make
type uses a specific group of materials. Table 3-5 them readily visible when exposed to natural or
Table 3-5 . - Penetrant inspection types, methods, and

material groups
s
MIL- I-25135
Penetrant Material Family of Items
e Type Method Used Group Used In Group
m I А Water-washable Group IV Consists of a water-washable

is fluorescent dye fluorescent penetrant and a
m dry , wet , or non aqueous wet
on developer.
re I B Post -emulsifiable Group V Consists of a post -emulsifiable

to fluorescent dye. fluorescent penetrant , an emul
is sifier, and a dry , wet , or non
he aqueous wet developer.
he
cts . Group VI Consists of a high -sensitivity
to post-emulsifiable fluorescent
ces penetrant , an emulsifier, and
me a dry , wet , or nonaqueous
fa wet developer.
Live
I с Solvent-removable Group VII Consists of a solvent- remov
at a
n is fluorescent dye . able fluorescent penetrant, a
of penetrant remover (solvent) and
e of a nonaqueous wet developer.
er or
II A Water-washable Group III Consists of a water -washable
dry
visible dye . visible dye penetrant and a
osed, dry , wet , or nonaqueous
crant wet developer .
ction
nder
II B Post -emulsified Group II Consists of a post-emulsifi
sible
visible dye . able visible dye penetrant,
nder an emulsifier , and a dry , wet ,
or nonaqueous wet developer .
oved
II с Solvent- removable Group I Consists of a solvent-remov
visible dye . able visible dye penetrant, a
penetrant remover (solvent ),
and a dry , wet , or nonaqueous
wet developer .
ction
scent
47
artificial white light. Penetrants in group I are Sulfonates in the emulsifying agents will not
removed by wiping with a cloth dampened by a affect nickel bearing steels .
specially prepared compatible solvent supplied NOTE : This method is not recommended for
with the portable penetrant kit . Penetrants in detecting extremely fine intergranular corrosion
group II are water washable (for removal) after or stress corrosion defects.
application of an emulsifier. This two -step The water -washable flourescent dye penetrant
process makes group II penetrants more suitable used in this type/method insures good visibility
for detecting wide , shallow defects. Group II of flaw patterns and can be easily washed off
penetrants are referred to as post-emulsifiable with water . Since it is considered a one- step
penetrants. Group III penetrants contain an process , it is fast and economical in time and is
emulsifier which makes them water washable as relatively inexpensive to perform . This process is
furnished . not reliable in finding scratches and shallow
Group IV through VII penetrants contain discontinuities as the penetrant is susceptible to
dyes which will fluoresce (glow ) when exposed overwashing. It is not reliable on anodized
to black light . Group IV penetrants contain an surfaces, and the penetrant can be affected by
emulsifier which makes it water washable as acids and chromates.
furnished. Groups V and VI are water washable Following precleaning and drying , the water
after application of an emulsifier the same as washable fluorescent penetrant is applied to the
group II . Group VII penetrants are removed by
surface being inspected by dipping, flow -on ,
wiping with a solvent-dampened cloth the same spraying, or brushing methods . After the pre
as group I. determined dwell time , it is flushed from the
surface with a low-pressure (20-30 psi) spray of
Selection of Inspection Process cold water . The developer is then applied and
The selection of the best type of penetrant
will cause the penetrant to bleed from any
discontinuities or defects, and these flaw indica
inspection suitable for the job at hand will tions will become visible when exposed to black
depend on several factors as follows:
light .
TYPE I , METHOD B , INSPECTION
1. Previously established requirements PROCESS . - This method is used when
specified on documents requiring the inspection . inspecting large volumes of parts which may
2. Penetrant sensitivity required . have defects that are contaminated with in
3. Surface condition of the part .
service soils or that may be contaminated with
4. Configuration of the part .
acids or other chemicals that will harm water
5. Number of parts to be tested .
6. Facilities and equipment available . washable penetrants. It is the type/method
recommended for use when :
7. Effect of the penetrant chemicals on the
material being tested .
A higher sensitivity than that offered by Type
I , Method A , is required .
TYPE I, METHOD A,
A, INSPECTION Discontinuities are wider than their depth .
PROCESS . - This method lends itself to inspect
-
Inspecting parts for stress cracks, inter

ing large volumes of parts , large areas , rough granular corrosion , or grinding cracks.
surfaces, and threads and keyways. It is the Variable , controlled sensitivities are necessary
recommended type /method to be used when : so that nondetrimental discontinuities can be
Discontinuities are not wider than their disregarded while harmful or detrimental ones
depth. can be detected .
The lowest flourescent penetrant sensitivity is The group V penetrant used with this type/
sufficient to detect the defects inherent to the method is more sensitive than the group IV
part . penetrant of Type I , Method A ; however, the
Removal of excess penetrant may be difficult group VI penetrant used with Type I , Method B ,
due to rough surfaces on the part. is more sensitive than group V.
48
NOTE : Only group VI materials are used for spraying, or brushing methods . After the pre
inspecting for stress cracks or intergranular determined dwell time , it is then removed with
corrosion . the solvent remover . The part is thoroughly
The fluorescent penetrant used in this process dried and developer is applied . Penetrant will
is more brilliant than other processes and affords bleed from any discontinuities or defects and
greater visibility when exposed to black light. the flaw indications will be apparent when
For field use where light exclusion is not always exposed to black light .
possible ,, it provides the greatest degree of TYPE II , METHOD A, INSPECTION
f
brilliance. PROCESS . - This process is utilized for inspect
P The Type I , Method B , process is highly ing surfaces when the circumstances described
is sensitive to fine defects and is also good on for Type I , Method A , exist and a fluorescent
८.
is wide , shallow defects. The penetrant washes dye penetrant is not necessary. A black light is
easily after emulsification and the penetrant is not needed ; therefore, the work area need not
not as susceptible to overwashing. Since it is be darkened . The process is relatively in
ed considered a two-step process , because of the expensive , highly portable , excellent for spot
emulsifier, it is slower than Type I , Method A. checking , and can be used on anodized parts .
The process is not as good on rough surfaces, The penetrant is easily washed off with fresh
er keyways, or threads ; and because of the extra water .
he materials used in the inspection , it is slightly Following precleaning and drying , the water
on , more expensive. washable visible dye penetrant is applied by
re Following precleaning and drying, the post dipping, flow -on, spraying, or brushing methods.
the emulsifiable fluorescent penetrant is applied to After the predetermined dwell time , it is flushed
of the surface being inspected . After being allowed from the surface with a low -pressure spray of
and to dwell for the predetermined time, the water and the surface is dried . The application
any emulsifier is applied. The emulsifier combines of developer then draws out penetrant left in
ica with the penetrant and is water washable . The any discontinuities or defects, and these flaw
ack excess penetrant is then removed using a low indications should appear clearly against the
pressure (30 to 40 psi) spray of cold water . The white developer background. The indications
part is then thoroughly dried and the developer can be easily seen in natural or artificial light .
JON applied. The penetrant is then drawn to the TYPE II , METHOD B , INSPECTION
when surface and any flaw indications will become PROCESS . - This method is used when a higher
may apparent as a brilliant greenish -yellow color sensitivity than that afforded by Type II ,
in when exposed to black light. The sensitivity of Method A, is required . It is used when inspecting
with this process can be controlled by the type of large volumes of parts , parts that are con
ater penetrant used , dwell time , emulsifying time,
>
taminated with acid or other chemicals that will
thod rinsing technique, and drying temperature and harm water-washable penetrants , parts which
time. may have defects that are contaminated with
TYPE I, METHODC , INSPECTION
inservice soils , and for inspecting finished sur
Type PROCESS . - This method is used for spot inspec faces and other general purpose applications .
tion on large or small parts where the water The materials in this process are the most
h. rinsing method is not fensible because of part sensitive of the visible dye penetrant inspection
inter size , weight, surface conditions , and lack of methods ; however , it is not recommended for
water , or there is no heat for drying or field use. detecting extremely fine intergranular corrosion
essary The use of solvent required to remove the or stress corrosion defects.
an be penetrant prohibits this process in inspecting Following precleaning and drying, the post
ones large areas. Its sensitivity can also be reduced by emulsifiable visible dye penetrant is applied to
the application of excessive amounts of the surface being inspected by dipping , flow -on,
penetrant remover . spraying, or brushing methods. After this group
type/
up IV Following precleaning and drying, the solvent II penetrant is allowed to dwell for a predeter
er , the removable fluorescent penetrant is applied to mined time , the emulsifier is applied . The
nod B , the surface being inspected by dipping , flow -on , emulsifier combines with the penetrant, which
49
becomes water washable . The excess penetrant is to the flaw openings wetted by the penetrant
then washed off using a low-pressure ( 30-40 psi) liquid and provides sharp flaw delineations. It is
spray of cold water . Application of the desired applied by dipping, dusting , or flowon method .
developer will then draw out and absorb the Aqueous wet developer consists of an
intense red penetrant from the discontinuity to absorbent powder supplied in dry form which is
provide a clear indication against the white mixed and suspended in water for application to
developer background. the part being penetrant inspected . The suspen
TYPE II II , METHOD C , INSPECTION sion of the wet developer must be agitated to
PROCESS . - This method is used when spot insure thorough suspension of the absorbent
inspection is required and where water rinsing is powder in the water. Excess penetrant is re
not feasible . The use of solvent in removing the moved from the part and the wet developer is
penetrant prohibits inspection of large areas and applied to the part while it is still wet . The wet
the process is not adaptable for detecting developer, on drying , provides an absorbent
extremely fine defects. white background for maximum color contrast
Following precleaning and drying , the solvent and causes the penetrant to bleed from the flaw
removable visible dye penetrant is applied as cavity , obtaining increased inspection accuracy .
with previous methods . After the predetermined Wet developers cause greater bleeding and are
dwell time , it is removed from the surface with more sensitive when applied as a spray . They are
solvent remover and the part is thoroughly applied by dipping or flow -on method .
dried . The application of the developer draws Nonaqueous wet developer consists of an
out the bright red indication as with the other absorbent powder suspended in aa volatile liquid .
two visible penetrant types and methods. This developer offers the highest relative
EMULSIFIERS. -The emulsifiers discussed sensitivity and is used primarily for spot inspec
under the various types and methods are tion where the surface being inspected has not
liquid additives which, when applied to post been heated during the process. The sensitivity
emulsifiable penetrants, combine with the of the developer can be increased by vibrating
excess surface penetrant to render it water the spray gun during application . The preferred
removable . These emulsifiers have low pene method of application is spraying. It may also be
trating properties , a necessary feature to avoid applied by brushing, but this is not generally
having the emulsifier remove the penetrant from preferred .
the discontinuity. They are of a contrasting NOTE : Nonaqueous developers should not be
color to the post-emulsifiable penetrant so that applied to a hot part until the part has been
it can be determined easily if all the emulsifier cooled enough to be hand held . Some of the
has been removed during the water rinsing. nonaqueous developers have a flash point of
Proper rinsing of fluorescent emulsifiers is 50° F.
checked using the black light . Emulsifier dwell Developer dwell time will depend on the type
time is that time which it takes for the emul of penetrant developer and the type of defect.
sifier to mix with the surface penetrant in order Allow sufficient time for an indication to form,
for it to rinse properly . but do not allow penetrant to bleed into the
DEVELOPERS. -As previously mentioned developer in such quantities to cause a loss of
under the types and methods ( table 3-5 ) , there defined indications .
are three types of developers-dry , aqueous wet ,
> The developer dwell time will vary from a few
and nonaqueous wet . minutes to an hour or more . A good rule of
Dry developer is a highly absorptive fluffy thumb is as follows: development time for a
white powder. It is applied to the part after it given material or type of defect is about one -half
has been thoroughly dried and provides a of the time considered proper for penetration
contrasting background to flaw indications and dwell time .
absorbs the penetrant at the defect. The dry Interpreting Results
type developers cause less bleeding of the
penetrant indication and thus provide better With penetrant inspections there are no false
resolution . The dry developer adheres primarily indications in the sense that such things occur in
50
etrant the magnetic particle inspection. However, there sectioning and viewing under black light will
s. It is are two conditions which may create accumula rapidly build up experience and knowledge of
thod . tions of penetrant that sometimes are confused the character of defects lying below various
fan with true surface cracks . types of indications. For best results , inspection
Lich is The first condition is a result of poor washing. should be done in a darkened area . The darke
on to If all the surface penetrant is not removed in the the area of inspection , the more brilliant the
spen washing or rinse operation following the indications will show . This is extremely impor
ed to penetration time , the unremoved penetrant will tant when looking for very fine indications . The
Ibent be visible . This condition is usually easy to inspection table should be kept free of random
is re identify since the penetrant will be in broad fluorescent materials . If penetrant has been
areas rather than in the sharp patterns found spilled in the inspection area , on the table , o
per is
e wet
with true indications . When accumulations of the operator's hands , it will fluoresce brilliantly
rbent unwashed penetrant are found on a part , the and may confuse the operator.
ntrast
part should be completely reprocessed . Degreas Visible dye penetrant indications appear as
e flaw
ing is recommended for removal of all traces of red lines. As the developer dries to a smooth
the penetrant. white coating , red indications will appear at the
агасу .
Another condition which may create false location of defects. If no red indications appear
d are
indications is where parts are press -fit to each there are no surface flaws present . No specia
ey are
other. For example , if a wheel is press -fit onto a lighting is required for the visible dye penetran
shaft , the penetrant will show an indication at inspection.
of an the fit line . This is perfectly normal since the It is possible to examine an indication of
liquid . two parts are not meant to be welded together. discontinuity and to determine its cause as wel
elative Indications of this type are easy to identify since as its extent . Such an appraisal can be made i
nspec they are so regular in form and shape. something is known about the manufacturing
as not The success and reliability of the penetration processes to which the part has been subjected
sitivity inspection depend upon the thoroughness with The extent of the indication , or accumulation o
orating which the operator prepares the part from the penetrant , will show the extent of the dis
eferred precleaning all the way through to the actual continuity , and the brilliance will be a measure
also be search for indications. It is not a method by of its depth . Deep cracks will hold more
nerally which a part is thrown into a machine which penetrant and therefore will be broader and
separates the good parts from the bad . The more brilliant . Very fine openings can hold only
not be operator must carefully process the part , search small amounts of penetrant and therefore wil
s been out indications , and then decide the seriousness appear as fine lines.
of the of defects found in order to determine the The most effective training tool for identify
pint of disposition of parts with indications. Penetrant ing and recognizing defects is a collection of
inspections are important tools for finding parts with typical defects which can be referred
ne type defects before those defects grow into failures. to frequently . Parts that have been rejected
defect. As an operator , it is up to you to get the most because of defects should be clearly marked o
form , out of the method used . partially damaged so that they will not be
to the Fluorescent indications , when viewed under confused with acceptable parts. Unless the
loss of black light , fluoresce brilliantly and the extent defects are extremely large the indications wil
of the indication marks the extent of the defect. remain on the parts for several months or longer
7 a few Pores , shrinkage, lack of bond and leaks will It is not advisable to reinspect any part using
rule of show as glowing spots , while cracks, laps, forging a different type process than the one originally
for a bursts or cold shuts will show as fluorescent used . Fluorescent penetrants and visible dye
ne -half lines. Where a large defect has trapped a penetrants are not very compatible ; therefore, il
tration quantity of penetrant the indications will spread at all possible , if reinspection of a part is
on the surface. Experience in the use of the required , the original process should be
method allows interpretations to be drawn from employed .
the extent of the spread as to the relative size of Documentation of penetrant inspections can
o false the defects. Grinding into certain defects, or be done on Support Action Forms (SAF's),
ccur in
51
Maintenance Action Forms (MAF's) , or Tech their shatter resistance , which is much higher
nical Directive Compliance Forms ( TDCF's ), than that of the airstretched solid plastics.
depending upon the circumstances which Stretched acrylic is a thermoplastic conform
warrant or require the inspection . Figure 3-3 ing to Military Specification MIL-P-25690. This
illustrates the use of a MAF for penetrant specification covers transparent , solid , modified
inspection during a calendar inspection , and acrylic sheet material having superior crack
figure 3-4 illustrates the TDCF being used propagation resistance (shatter resistance , craze
because of an Aircraft Bulletin . When the MAF resistance , fatigue resistance) as a result of
is used , the worker in most cases initiates and proper hot stretching.
completes the form , while the TDCF is usually Stretched acrylic is prepared from modified
initiated by Maintenance/Production Control, acrylic sheets , using a processing technique in
and the worker complies with it and completes which the sheet is heated to its forming tempera
the form . ture and then mechanically stretched so as to
Detailed information on MAF's and TDCF's increase its area approximately 3 or 4 times with
and their uses is covered in Military Require a resultant decrease in its thickness. Most of the
ments for Petty Officer 3 & 2 , NavPers 10056-C , Navy's high -speed aircraft are equipped with
and OpNav 4790.2 ( Series) Instruction. canopies made from stretched acrylic plastic .
Identification
Most transparent plastic sheet used in naval

NONMETALLIC MATERIALS
aircraft is manufactured in accordance with
various MIL specifications, some of which are
TRANSPARENT PLASTICS listed in table 3-6. Individual sheets are covered
Transparent plastic materials used in aircraft with a heavy masking paper on which the
specification number appears . In addition to
canopies, windshields, and other transparent serving as a means of identification, the masking
enclosures may be divided into two major
classes, or groups, depending on their reaction to paper helps to prevent accidental scratching of
heat . They are the THERMOPLASTIC materials the plastic during storage and handling.
and the THERMOSETTING materials . Table 3-6 . - Transparent plastics.
Thermoplastic materials will soften when
heated and harden when cooled . These materials
can be heated until soft, formed into the desired
shape , and when cooled will retain this shape .
The same piece of plastic can be reheated and Type Specification No.
reshaped any number of times without changing
the chemical composition of the material. Solid Thermoplastic
Thermosetting plastics harden upon heating , Thermoplastic
Heat - resistant MIL - P - 5425
and reheating has no softening effect. They
acrylic
cannot be reshaped after once being fully cured Modified acrylic MIL- P- 8184
O
by the application of heat . These materials are Stretched modified MIL - P - 25690
rapidly being phased out in favor of stretched acrylic (8184)
acrylic , a thermoplastic material. Thermosetting
Transparent plastics are manufactured in two Polyester craze MIL- P- 8257
forms of material -solid (monolithic ) and resistant
laminated. Laminated plastic consists of two
Laminated
sheets of solid plastic bonded to a rubbery MIL- P- 25374
Laminated modified C
inner -layer material similar to the sandwich

material used in plate glass . acrylic (8184)
Laminated transparent plastics are well suited
to pressurized applications in aircraft because of
52
ch higher
ics . MAINTENANCE ACTION FORM
conform OPNAV FORM 4790/40 ( 10-69 ) S / N.0107.770.4400
1. JOB CONTROL NUMBER 2. TYPE EQUIP . 3. BU/ SER NO . 4. ACTION 5. WORK 6. MAINT . LEVEL 7. ACTION DATE
ORG . CENTER
-690 . This ORG . DATE SER SUF
2 3
modified PH5 2020 A00 1515 77 PHS 140 XORG INT DEP 2021
AAEA
8. WORK UNIT CODE 10. TYPE MAINT . 11. ACTION 12. MAL 13. ITEMS 14. MAN . 15. EMT 16 .
ior crack 9. WHEN DISCD
TAKEN PROC . HOURS
nce , craze 030

result of 20. REMOVEC ГЕМ
o Р 000 o 114 14
14
21 INSTALLED ITEM
.1 MFGR 2 SERIAL NUMBER . 1 MFGR .2 SERIAL NO .
modified
3 PART NUMBER 4 TIME / CYCLES .3 PART NUMBER 4 TIME CYCLES
unique in
B. DISCREPANCY C. CORRECTIVE ACTION
tempera
so as to
mes with
COMPLETE CARDS 133A - 133A.1 OF COMPLETED CARDS 133A-133A./, LOOK PHASE
ost of the
CALENDAR INSPECTION AND DYE PENETRANT INSPECTION FOR
CALENDAR INSPECTION.
ped with
astic .
D. ENTRIES REQUIRED SIGNATURE E. CORRECTED BY F. INSPECTED BY G. SUPERVISOR
in naval CONFIGURATION YES NO
LOG YES NO
nce with ACCESS RECORD YES NO
I.Bulbur.A52. 2.HinsonAmbe Ç.Comes AMSC
which are 30 .
REPAIR CYCLE DATA
40 .
FAILED MATERIAL
- covered DATE DATE
1
ACT
TKN MAL
3
QTY
4
MFGR
5
PART NUMBER / REF .. SYMBOL
hich the
1. REMOVED 5. TO AWP
Jition to RECEIVED
2. 6. OFF AWP
MATL . CONTROL
masking
3. WORK STARTED 7. TO AWP
ching of
4. COMPLETED 8. OFF AWP
RFI B COND R/ S 9 .
0.
H. PCN PRIORITY DATE DUE
IN OUT
J. K.
ACCUMULATED HOURS REQUIRED MATERIAL
DAT TIME
tion No. NAME / SHIFT DATE MAN - HOURS EMT REQ . NO . MFGR PART NUMBER OTY PRI
ORD REC
AWP
-5425
8184
25690
TOTAL
8257
AM.5
25374
Figure 3-3.- MAF used for penetrant inspection during calendar inspection .
53
TECHNICAL DIRECTIVE COMPLIANCE FORM

OPNAV FORM 4790/43 ( 10-69) SIN 0107-770-4600
1. JOB CONTROL NUMBER 2. TYPE 3. BU / SER NO . 4. ACTION 5. WORK 6. MAINTENANCE LEVEL 7. ACTION
STATISTICAL
EQUIP ORG CENTER 1 2 3 DATE
PHS 2020 126 AAEA 156994 PH5 120 XORG INT DEP
202 /
DATA
8. SYSTEM 9. STATUS10 . ITEMS 11. MAN HRS 12. EMT 13. INTERIM 14. TECHNICAL DIRECTIVE IDENTIFICATION 15. CORR
PROC
1 CODE .2 BASIC NO ... 3 REV . , 4 AMD S PART .6 KIT
11 ves X NO
C 3.5 3.5 74 80 00
46 OLD ITEM 47. NEW ITEM
.1 MFGR .2 SERIAL NUMBER .1 MFGR 2 SERIAL NUMBER
3 PART NUMBER 3 PART NUMBER

.CONTROL
A. PRI B PRIMARY C. ASSISTANT WORK CENTERS D. BY DATE E EST M / H F CREW G. KIT REQD . H. SE REQD .
MAINT
WORK CENTER SIZE
3 120 none 2024 4.0 1 Yesby no respono

YES NO
1 . REMARKS
Perform dye penetrant inspection as per A / C Bulletin No. 80

MATERIAL
A MATERIAL / KIT STOCK NUMBER B DATE ORDERED C. STUB NO . D. DATE F. ISSUED BY

RECEIVED
E REMARKS G DELIVERED BY
H. DATE
CENTER
A. STATUS G - STATUS CODES

WORK
A -ASSISTING WORK CENTER

B. SAMI / CAMI
NO .
Performed dye penelandinapeetim sapo C - COMPLIED WITH
D - DOES NOT
D. At Bulletin e 80-70 crackerwealed
ACCOMPLISHED BY E. INSPECTED BY F SUPERVISOR
APPLY
P - PREVIOUSLY COMPLIED WITH
RBibles Aus27.Henson Ams E Robinson AMSC W - WORK IN PROGRESS

&RECORDS
A. COMPLIANCE RECORDED ON HISTORICAL RECORDS B. DATE SIGNATURE

LOGS
LOG ACCESSORY CARD
C. CONFIGURATION FORM DATE SIGNATURE

20247 Priorazi
D
YES NO
2026 m . Prior AZI .- 10067
AM.7
Figure 3-4 . - TDCF documentation for penetrant inspection .
Identification of unmasked sheets of plastic is Storage and Handling

often difficult; however, the following informa
- tion may serve as an aid . MIL -P -8184 , a Transparent plastic sheets are available in a
modified acrylic plastic, has a slight yellowish number of thicknesses and sizes which can be
tint when viewed from the edge ; MIL-P-8257 , a cut and formed to required size and shape .
thermosetting polyester plastic , has a bluish or These plastics will soften and/ or deform when
blue-green tint ; and MIL - P -5425 , heat-resistant heated sufficiently ; therefore, storage areas
acrylic, is practically clear. In addition , stretched having high temperatures must be avoided . ·
acrylic sheets and fabricated assemblies are Plastic sheets should be kept away from heating
permanently marked to insure positive iden coils, radiators, hot water , and steam lines.
tification . Storage should be in a cool , dry location away
Plastic enclosures on aircraft may be distin from solvent fumes, such as may exist near paint
guished from plate glass enclosures by tapping spray and paint storage areas . Paper masked
lightly with a blunt instrument. Plastic will transparent plastic sheets should be kept indoors
resound with a dull thud or soft sound , whereas as direct rays of the sun will accelerate deteriora
plate glass will resound with a metallic sound or tion of the masking paper adhesive, causing it to
ring. cling to the plastic so that removal is difficult.
54
Plastic sheets should be stored with the removed permanently ; therefore, prevention
masking paper in place , in bins which are tilted crazing is a necessity. )
at approximately 10 degrees from the vertical to When it is necessary to remove masking pap
prevent buckling. If it is necessary to store from the plastic sheet during fabrication , th
sheets horizontally , care should be taken to surface should be remasked as soon as possibl
avoid chips and dirt getting between the sheets. Either replace the original paper on relative
Stacks should not be over 18 inches high , and flat parts or apply a protective coating on curve
small sheets should be stacked on the larger ones parts .
to avoid unsupported overhang. Storage of
transparent plastic sheets presents no special fire REINFORCED PLASTICS
hazard , as they are slow burning.
>
Masking paper should be left on the plastic Glass fiber reinforced plastic and honeycom
sheet as long as possible . Care should be are used in the construction of radome
exercised to avoid scratches and gouges which wingtips , stabilizer tips , antenna covers , fairing
may be caused by sliding sheets against one access covers , etc. It has excellent dielectr
another or across rough or dirty tables. characteristics, making it ideal for use
Formed sections should be stored so that they radomes. Its high strength/weight ratio , resis
ance to mildew and rot , and ease of fabricatic
are amply supported and there is no tendency make it equally suited for other parts of th
for them to lose their shape . Vertical nesting aircraft .
should be avoided . Protect formed parts from The manufacture of reinforced plast
temperatures higher than 120° F. Protection
from scratches may be provided by applying a laminates involves the use of liquid resins í
inforced with a filler material . The resin , whe
protective coating .
properly treated with certain agents known
If masking paper adhesive deteriorates catalysts , or hardeners, changes to an infusib
through long or improper storage , making re solid .
moval of paper difficult, moisten the paper with The reinforcement materials are impregnate
aliphatic naphtha, which will loosen the with the resin while the latter is still in the liqu
adhesive . Sheets so treated should be washed ( uncured ) state . Layers or plies of cloth a
immediately with clear water. stacked up and heated under pressure in a mo
CAUTION : Aliphatic naphtha is highly to produce the finished , cured shape . Anoth
volatile and flammable . Extreme care should be technique , called “ filament winding,” consists
exercised when using this solvent . winding a continuous glass filament or tap
Do not use gasoline, alcohol , kerosene , impregnated with uncured resin , over a rotatir
xylene , ketones , lacquer thinners, aromatic male form . Cure is accomplished in a mann
hydrocarbons , ethers , glass cleaning compounds, similar to the woven cloth reinforced laminate
or other unapproved solvents on transparent Glass fiber reinforced honeycomb consists of
able in a acrylic plastics to remove masking paper or relatively thick, central layer called the core ar
7 can be
other foreign material , as these will soften two outer laminates called facings. (See figu
shape. and/or craze the plastic surface. ( NOTE : Just as 3-5 . )
m when
woods split and metals crack in areas of high, The core material commonly used in radom
se areas localized stress , plastic materials develop, under construction consists of a honeycomb structu
avoided. similar conditions, small surface fissures called made of glass cloth impregnated either with
heating CRAZING . These tiny cracks are approximately polyester or epoxy , or a combination of nylo
m lines. perpendicular to the surface, very narrow in and phenolic resin . The material is normal
on away width, and usually not over 0.01 inch in depth . fabricated in blocks that are later cut on
ar paint These tiny fissures are not only an optical bandsaw to slices of the exact thickness desire
masked defect, but also a mechanical defect, inasmuch or it may be originally fabricated to the prop
indoors as there is a separation or parting of the thickness.
teriora material . Once a part has been crazed , neither The facings are made up of several layers
ng it to the optical nor mechanical defect can be glass cloth , impregnated and bonded togeth
cult .
55
balsa wood . This material is found in a variety of

places such as wing surfaces, decks , bulkheads,
HONEYCOMB stabilizer surfaces, ailerons, trim tabs, access
CORE
doors , and bomb bay doors. Figure 3-6 il
lustrates one type of sandwich construction
using a honeycomb-like aluminum alloy core,
sandwiched between aluminum alloy sheets,
called facings. The facings are bonded to the
lightweight aluminum core with a suitable
adhesive so as to develop a strength far greater
than that of the components themselves when
used alone .
Another type structural sandwich construc
2 FA CINGS
( MULTIPLE LAYERS OF GLASS CLOTH)
tion consists of a low-density balsa wood core
combined with high -strength aluminum alloy
facings bonded to each side of the core . The
grain in the balsa core runs perpendicular to the
AM.230 aluminum alloy facings, and the core and alumi
Figure 3-5. -Reinforced plastic. num facings are firmly bonded together under
controlled temperatures and pressures .
with resin .. Each layer of cloth is placed in The facings in this type construction carry the
position and impregnated with resin before major bending loads, and the cores serve to
another layer is added . Thicker cloths are support the facings and carry the shear loads.
normally used for the body of the facings, with The outstanding characteristics of sandwich
one or more layers of a finer weave cloth on the construction are strength , rigidity , lightness, and
surface . surface smoothness .
The resins are thick , sirupy liquids of the
so -called contact-pressure type ( requiring little
or no pressure during cure ) , some times referred
to as contact resins. They are usually thermoset
ting polyester or epoxy resins. Cure can be UPPER FACING
effected by adding a catalyst and heating , or (SKIN)
they can be cured at different temperatures by
adjusting the amount and type of catalysts. -CORE - ALUMINUM
Inspection and repair procedures for reinforced ADHESIVE TAPE
HONEYCOMB
plastic are covered in chapter 7 of this manual.
SANDWICH CONSTRUCTION
LOWER FACING
From the standpoint of function, sandwich (SKIN )
parts in naval aircraft can be divided into two
broad classes: ( 1 ) radomes and (2 ) structural.
The first class , radomes, is a reinforced plastic
sandwich construction designed primarily to N
permit accurate and dependable functioning of TUISITIO
011
the radar equipment . This type construction was
discussed in the preceding section under rein
forced plastics .
The second class, referred to as structural
sandwich , normally has either metal or rein AM.231
forced plastic facings on cores of aluminum or Figure 3-6 . - Sandwich construction .
56
CHAPTER 4
AIRFRAME CONSTRUCTION
Familiarity with the various terms used in outline and general design. They vary mainly in
reference to airframe construction is one of the size and arrangement of the different compart
first requirements of the Aviation Structural ments . Detail design varies with the manufac
Mechanic. Maintenance of the airframe is turer and the requirements of the type of service
primarily the responsibility of the AMS; there which they are intended to perform . For
fore, he should be familiar with the principal instance , the U- 16 (widely used in Search and
units which make up the airframe and know the Rescue ) may have to operate as an amphibious
purpose , location , and construction features of aircraft. When operating
operating from water the
each . fuselage , being watertight , keeps the aircraft
The airframe of a fixed -wing (sometimes afloat. In fact, the fuselage so nearly performs
referred to as " conventional” when distin the function of a boat that it is called the
guishing from helicopters) aircraft is generally HULL .
considered to consist of five principal units-the Two general types of fuselage construction
fuselage, wings , stabilizers, flight control sur are the WELDED STEEL TRUSS and the
faces, and landing gear. Helicopter airframes MONOCOQUE designs . The welded steel truss is
consist of the fuselage (or hull) , main rotor and used in many of the smaller, civilian type
related gearbox , tail rotor (on helicopters with a aircraft and was formerly used in many Navy
single main rotor), and the landing gear . A aircraft. It is still being used in some helicopters.
further breakdown of these principal units into An example of truss type construction is shown
major components is made in this chapter, in figure 4-1 .
describing the purpose , location , and construc
tion features of each.
FIXED -WING AIRCRAFT
FUSELAGE
The fuselage is the main structure or body of

the airframe. It provides space for personnel,
cargo , controls, and most of the accessories and
other equipment . In single-engine aircraft, it also
houses the powerplant . In multiengine aircraft
the engines may either be in the fuselage, or
attached to or suspended from the wing struc
ture .
Fuselages of the various types of naval aircraft AM.232
have much in common from the standpoint of Figure 4.1 . - Truss type fuselage construction .
57
The monocoque design relies largely on the which usually extend across several points of
strength of the skin or covering to carry the support. The longerons are supplemented by
various loads ( discussed in chapter 3 ) . This other longitudinal members, called STRING
design may be divided into three classes : ERS. Stringers are more numerous and lighter
MONOCOQUE , SEMIMONOCOQUE, and RE in weight than are longerons. The vertical
INFORCED SHELL . The monocoque has as its structural members are referred to as BULK
only reinforcement vertical rings , station webs , HEADS, FRAMES, and FORMERS . The
formers, and bulkheads . The semimonocoque heaviest of these vertical members are located at
has, in addition to these vertical reinforcements, intervals to carry concentrated loads and at
the skin reinforced by longitudinal members. points where fittings are used to attach other
The reinforced shell has the skin reinforced by a units, such as the wings , powerplant , and
complete framework of structural members. stabilizers . Figure 4-2 shows a modified form of
Different portions of the same fuselage may the monocoque design now used in all combat
belong to any one of these three classes, but type aircraft.
most Navy aircraft are considered to be of The metal skin , or covering, is riveted to the
semimonocoque type construction . longerons, bulkheads , and other structural
The semimonocoque fuselage is constructed members and carries part of the load . Skin
primarily of the alloys of aluminum and thickness varies with the loads carried and the
magnesium , although steel and titanium are stresses sustained .
found in areas of high temperatures. Primary There are a number of advantages in the use
bending loads are taken by the LONGERONS, > of the semimonocoque fuselage. The bulkheads,
I TT
T DI
r T
nT
Y
J A
SN
TOTI
TE
NA
RY UUENC /2 0/24
AM.233
Figure 4-2 . - Semimonocoque fuselage construction .
58
Chapter 4-AIRFRAME CONSTRUCTION
frames, stringers, and longerons facilitate the Various points on the fuselage are located by
design and construction of a streamlined station number . Station 0 (zero) is usually
fuselage, and add to the strength and rigidity of located at or near the nose of the aircraft, an
the structure . The main advantage ; however, lies other stations are located at measured distance
in the fact that it does not depend on a few (in inches) aft of station zero .
members for strength and rigidity. This means A typical station diagram is shown in figur
that a semimonocoque fuselage, because of its 4-3 . On this particular aircraft, station 0 i
stressed -skin construction , may withstand located 16 inches forward of the nose . Th
considerable damage and still be strong enough fuselage break ( for engine removal ) is located a
to hold together. station 277.5 .
Fuselages are generally constructed in two or Quick access to the accessories and othe
more sections. On fighters and other small types equipment carried in the fuselage is provided fo
of aircraft , they are generally made in two or by numerous access doors , inspection plates
three sections , while larger aircraft may be made landing wheel wells, and other openings
up of as many as six sections . Servicing diagrams showing the arrangement o
131.9
111.8
-277.5
22
8CANTED
37
BLKD
103
. 1.8
47
27
91
-9961
170.2
184.2
54.5
337.5
61.3
119.5
307.5
152
131
93
376
364
283
9061
418
128.5
177.2
163,8
292.5
141
322.5
400
373
352
.
AM.23
Figure 4.3. -Typical station diagram .
equipment and location of access doors are particular design for any given aircraft depend
supplied by the manufacturer in the Main upon a number of factors; for example , size
tenance Instructions Manual and Maintenance weight , and use of the aircraft, its desire
Requirements Cards for each aircraft. Figure 4-4 landing speed and desired rate of climb. Th
shows the servicing diagram for a typical air wings are designated as left and right, cor
craft. responding to the left and right sides of the pilo
when seated in the aircraft.
The wings of Navy aircraft are usually o
WINGS all-metal construction with cantilever design
that is no external bracing . Both aluminum allo
The wings are airfoils designed to develop the and magnesium alloy are used extensively i
major portion of the lift of the aircraft. The wing construction . The internal structure i
59
15 5,13 8
13
19 16 9
16 12
15
6,9,10
15 9,16 4 13,14
18 17 3 7 6,9 2
AM.235
1. Forward refueling and defueling receptacle. 10. Pneumatic system servicing.
2 Aft refueling and defueling receptacle. 11 . Compressor oil reservoir .
3. Oil filling and draining. 12 . Pneumatic system chemical dryer.
4. Liquid oxygen filling and draining. 13. Pneumatic system depressurizing and draining.
5. Emergency oxygen servicing. 14. Electronic pressurizing desiccator. .
6. Hydraulic reservoir servicing panel. 15 . Pitot-static system draining.

7. Hydraulic systems servicing. 16. Landing gear strut servicing.
8. Hydraulic reservoir air dump valves and sight 17. Arresting gear snubber.
gages. 18. Arresting gear hook bumper.
9. Accumulator servicing . 19 . A.c external power.
Figure 4-4 . - Typical servicing diagram .
60
Chapter 4 -AIRFRAME CONSTRUCTION
made up of SPARS and STRINGERS running the ribs to the spars. The spars support all
spanwise , and RIBS and FORMERS running distributed loads as well as concentrated
chordwise (leading edge to trailing edge). The weights , such as fuselage, landing gear , and (on
spars are the principal structural members of the multiengine aircraft) nacelles . Corrugated sheet
wing and are often referred to as BEAMS. aluminum alloy is sometimes used as a subcover
One of the numerous methods of wing ing for wing structures , especially on very large
construction is shown in figure 4-5 . In this aircraft. The C- 121 wing has this type of
illustration two main spars are used with ribs construction .
placed at intervals to space them and develop The wing, like the fuselage, is constructed in
wing contour . This is called TWO-SPAR sections . One commonly used type is made up
construction . Other variations of wing construc of a CENTER SECTION with OUTER PANELS
tion include MONOSPAR (one spar), MULTI and WINGTIPS . Another arrangement may have
SPAR ( three or more spars) , and BOX BEAM in
> WINGSTUBS as integral parts of the fuselage in
which stringers and spar-like sections are joined place of the center section , although from the
together in a box shaped beam about which the outside they are very much like the wing center
remainder of the wing is constructed . section in appearance .
The skin is riveted , or in some cases attached Inspection openings and access doors are
with screws, to all these internal members and provided , usually on the lower surfaces of the
carries part of the wing stresses . During flight, wing, and drain holes are placed in the lower
applied loads which are imposed on the wing surfaces. On some aircraft, built-in walkways are
structure act primarily on the skin . From the provided on the areas where it is intended that
skin they are transmitted to the ribs and from personnel will walk or step . On others there are
TRAILING
EDGE
he
Zu
82 r
1 NOSE
bia FAIRING
ZILE
RIBS
SPARS
AM.236
Figure 4-5 . - Two-spar wing construction .
61
LEFT AND RIGHT WING

JACK POINT FITTINGS
A777 HU
MAIN STRUT
JACK POINT
R / H AND L / H
FUSELAGE JACK
POINT FITTING
BO
TAIL JACK
POINT FITTING
AM.237
Figure 4-6 . - Typical jacking diagram .
no built-in walkways, but removable mats or STABILIZERS

covers are used to protect the wing surface when
servicing the aircraft. The stabilizing surfaces of an aircraft consist
of vertical and horizontal airfoils, called the
Jacking points are provided on the underside VERTICAL STABILIZER (or fin ) and the
of each wing in the form of recessed openings HORIZONTAL STABILIZER . These two
for quick installation of jackpads . A typical airfoils, together with the rudder and elevators ,
jacking diagram is shown in figure 4-6. On some form the tail section . For inspection and main
aircraft the jack pads may be used as tiedown tenance purposes the entire tail section is
fittings for tiedown of the aircraft; other aircraft considered a single unit of the airframe called
make use of removable jack pads and more the EMPENNAGE.
convenient tiedown fittings. Jacking and The primary purpose of the stabilizers is to
tiedown procedures are described fully in stabilize the aircraft in flight, that is , to keep the
>
chapter 12 . craft in straight and level flight. The vertical

stabilizer maintains the stability of the aircraft
Various points on the wing are located by about its vertical axis. This is known as
station number. Wing station 0 (zero) is located DIRECTIONAL STABILITY . The vertical
at the centerline of the fuselage, and all wing stabilizer usually serves as the base to which the
stations are measured outboard from that point, rudder is attached . The horizontal stabilizer
in inches . provides stability of the aircraft about the lateral
62
axis. This is LONGITUDINAL STABILITY . It movement is about the lateral axis. The rudder,
usually serves as the base to which the elevators attached to the vertical stabilizer, determines the
are attached . horizontal direction of flight ( turning or yawing
On all high -performance aircraft the motion) of the aircraft. This is DIRECTIONAL
horizontal stabilizer is a movable airfoil, con CONTROL and it occurs about the vertical axis
trollable from the cockpit , commonly referred of the aircraft .
to as the “flying tail.” At extremely high ( at or The ailerons and elevators are operated from
about the speed of sound ) speeds , the elevators the cockpit by a control stick on fighter type
have a tendency to lose their effectiveness. aircraft and by a wheel and yoke assembly on
Forces acting upon the control stick become large aircraft such as transports and patrol
very high , and longitudinal control of the planes. The rudder is operated by rudder pedals
aircraft becomes difficult. By changing the angle on all types of aircraft .
of attack of the stabilizer , adequate longitudinal The ailerons are operated by a lateral ( side to
control is maintained . This is accomplished by side ) movement of the control stick, or a turning
raising or lowering the leading edge of the motion of the wheel on the yoke , and are
stabilizer. interconnected in the control system so that
Construction features of the stabilizers are in they work simultaneously in opposite directions
many respects identical with those of the wings. to one another . As one aileron moves downward
They are usually of all-metal construction and of to increase lift on its side of the fuselage , the
cantilever design . Monospar and two spar aileron on the opposite side of the fuselage
construction are both commonly used . Ribs moves upward to decrease lift on its side . This
develop the cross - sectional shape . Fairing is used opposing action results in more lift being
to round out the angles formed between these produced by the wing on one side of the
surfaces and the fuselage . fuselage than on the other side , the result being
a controlled movement or roll due to unequal
forces on the wings.
FLIGHT CONTROL SURFACES The elevators are operated by a fore- and -aft
movement of the control stick or yoke , as the
>
The flight control surfaces are hinged or case may be . Raising the elevators causes the
movable airfoils designed to change the attitude aircraft to climb ; lowering the elevators causes it
of the aircraft during flight. The basic controls to dive or descend . The elevators are raised by
are the AILERONS , ELEVATORS , and pulling back on the stick or yoke , and they are
RUDDER. A miscellaneous grouping of the lowered by pushing the stick or yoke forward .
remainder of the flight controls would include
the TRIM TABS , SPRING TABS , WING The rudder is operated by the rudder pedals
FLAPS , SPEED BRAKES , SLATS , > and and is used to move the aircraft about the
SPOILERS . vertical axis . Moving the rudder to the right
turns the aircraft to the right ; moving it to the
Basic Controls left turns the aircraft to the left. The rudder is
moved to the right by pushing the right rudder
pedal , and is moved to the left by pushing the
The basic controls -ailerons , elevators, and
rudder - are used to move the aircraft about its
left pedal.
three axes . ( See fig. 4-7 . ) The ailerons are Practically all high -speed aircraft have hy
attached to the trailing edge of the wings and draulic actuators incorporated within the flight
control the rolling ( or banking ) motion of the control systems to aid the pilot in movement of
aircraft. This is known as LONGITUDINAL the control surfaces at accelerated airspeeds.
CONTROL since the roll is about the longi Another method of decreasing the amount of
tudinal axis. The elevators , attached to the force required to operate the controls is by the
horizontal stabilizers, control the climb or use of spring tabs , which are described later.
descent ( pitching motion of the aircraft ) . This is The construction of control surfaces is similar
known as LATERAL CONTROL since the to that of the wing and stabilizers. They are
63
VERTICAL AXIS
LATERAL AXIS
ROLL
LONGITUDINAL AXIS
YAW
PITCH
AM.238
Figure 4-7 . - Axes and fundamental movements of the aircraft.
usually built around a single spar or torque tube . controls not designated as basic controls . These
Ribs are fitted to the spar near the leading edge, controls supplement the basic controls by aiding
and at the trailing edge are joined together with the pilot in controlling his aircraft. There are
a suitable metal strip or extrusion . The control various types used on naval aircraft, but only the
surfaces of some aircraft are fabric -covered , but most common are discussed here .
all jet aircraft have all-metal surfaces for TRIM TABS . - Trim tabs are small airfoils
additional strength . Some basic control surfaces recessed into the trailing edge of aa basic control
have lead counterweights inside the leading edge. surface. Their purpose is to enable the pilot to
This balances the surface , making it easier to trim out any unbalanced condition which might
move the surface in flight. Counterweights also exist during flight, without exerting any pressure
prevent the surface from fluttering during flight. on the control stick or rudder pedals. Each trim
For greater strength , especially in thinner tab is hinged to its parent control surface , but is
airfoil sections typical of trailing edges , a honey operated independently by a separate control.
comb type of construction is utilized . ( This type Trimming is accomplished by setting the tab
of material is described in detail in chapter 3. ) in the opposite direction to that in which it is
desired for the basic control surface to be
Miscellaneous Flight Controls moved . The airflow striking the trim tab causes
the larger surface to move to a position that will
Miscellaneous flight controls include those correct the unbalanced condition of the aircraft.
64
Chapter 4 - AIRFRAME CONSTRUCTION
For example , to trim out a hose-heavy condi

tion , the pilot sets the elevator trim tab in the
DOWN position . This causes the elevator to be
moved and held in the UP position , which in
turn causes the tail of the aircraft to be ered . PLAIN FLAP
Without the use of the trim tab , the pilot would
have to hold the elevator in the UP position by
exerting constant pressure on the control stick
or wheel .
Internal construction of trim tabs is similar to SPLIT FLAP
that of the other control surfaces, although
increasing use is being made of plastic materials
to fill the tab completely , thus improving its
stiffness. They may also be honeycomb filled.
Tabs are covered with either metal or reinforced LEADING EDGE
plastic . Trim tabs are actuated either electrically FLAP
or manually on all aircraft.
SPRING TABS . - Spring tabs are similar in
appearance to trim tabs , but serve an entirely
different purpose. Spring tabs are used for the
FOWLER FLAP
same purpose as hydraulic actuators, that is, to
aid the pilot iņ moving a larger control surface.
On the P - 2 aircraft, a spring tab is hinged to
the trailing edge of each aileron alongside the AM.239
trim tab . The spring tab is actuated by a Figure 4-8 . - Types of flaps.
spring -loaded , push-pull rod assembly which is
also linked to the aileron control linkage. The
linkage is connected in such a way that move
ment of the aileron in one direction causes the use of flaps during takeoff serves to reduce the
spring tab to be deflected in the opposite length of the takeoff run .
direction . This provides a balanced condition , Most flaps are hinged to the lower trailing
thus reducing the amount of force required by edges of the wings inboard of the ailerons ;
the pilot to move the ailerons. The deflection of however, leading edge flaps are in use on at least
the spring tab is directly proportional to the one model Navy aircraft, the F-4 , Phantom II .
aerodynamic load imposed upon the aileron. Four types of flaps are shown in figure 4-8 . The
Therefore, at low speeds the spring tab remains PLAIN type flap forms the trailing edge of the
in a neutral position with respect to the aileron airfoil when the flap is in the up position . In the
(faired ) and the aileron is then entirely manually SPLIT flap , the trailing edge of the airfoil is split
controlled. At high speeds , however , where the and the lower half is so hinged that it can be
aerodynamic load is great, the tab functions as lowered to form the flap. The FLOWER flap
an aid to the pilot in moving the primary control operates on rollers and tracks, causing the lower
surface. Spring tabs are referred to by some surface of the wing to roll out and then extend
manufacturers as balance tabs , other may call downward . The LEADING EDGE flap operates
them servo tabs . similar to the plain flap, that is, it is hinged on
WING FLAPS . - Wing flaps are used to give the bottom side and , when actuated , the leading
the aircraft extra lift. Their purpose is to reduce edge of the wing actually extends in a downward
the landing speed, thereby shortening the length direction to increase the camber of the wing.
of the landing rollout , and to facilitate landing Leading flaps are used in conjunction with other
in small or obstructed areas by permitting the type flaps.
gliding angle to be increased without greatly SPOILERS . - Spoilers, in general, are for the
increasing the approach speed. In addition, the purpose of decreasing wing lift; however, their
65
specific design , function , and use vary with
different type aircraft.
Lateral control of the A -5 is exercised entirely
The spoilers on the P-2 aircraft are long through a system of spoilers and deflectors. In
narrow surfaces, hinged at their leading edge to this installation , an automatic ratio changer
the upper wing skin . (See fig. 4-9 .) In the provides reduced throw of the spoilers and
retracted position , the spoiler is flush with the deflectors for the same amount of stick move
wing skin . The action of the spoilers is to ment when above a given speed . This reduces
destroy the smooth flow of air over the wing so the rate of roll and keeps it within controllable
that burbling takes place. The lift is consequent limits .
iy greatly reduced and considerable drag is SPEED BRAKES . - Speed brakes are hinged
added to the wing . Spoilers are effective for movable control surfaces used for reducing the
lateral control of the P - 2 at high angles of speed of aircraft. Some manufacturers refer to
a
ttack . In the extended position , the spoiler is them as DIVE BRAKES , others call them DIVE
pivoted up and forward approximately 60 FLAPS. On some aircraft they are hinged to the
degrees above the hinge point. sides or bottom of the fuselage, on others they
Another type of spoiler in common use is a are attached to the wings. Regardless of their
long, slender, curved and perforated baffle that location , speed brakes serve the same purpose on
is raised edgewise through the wing upper all aircraft on which they are used . Their
surface forward of the aileron . It also disrupts primary purpose is to keep the speed from
the orderly flow of air over the airfoil and building up too high in dives . They are also used
destroys lift. This type of spoiler is used on S -2 in slowing down the speed of the aircraft
aircraft and is also illustrated in figure 4-9. preparatory landing. Speed brakes are
The S-2 spoilers are actuated through the operated hydraulically or electrically .
same linkage that actuates the ailerons. This SLATS . - Slats are movable control surfaces
arrangement makes movement of the spoiler attached to the leading edge of the wing . When
dependent upon movement of the aileron. The the slat is retracted , it forms the leading edge of
linkage to the aileron is devised so that the the wing . When the slat is open ( extended
spoiler is extended only when the aileron is forward ), a slot is created between the slat and
raised. In other words, when the aileron moves the wing leading edge . Thus, high -energy air is
downward , no deflection of the spoiler takes introduced into the boundary layer over the top
place. of the wing . At low airspeeds this improves the
lateral control handling characteristics , allowing
the aircraft to be controlled at airspeeds below
the otherwise normal landing speed . This is
known as “ boundary layer control. ” Boundary
layer control is intended primarily for use during
>
operations from carriers; that is , for catapult

takeoffs and arrested landings .
Boundary layer control can also be ac
FLAP TYPE complished by directing high -pressure engine
bleed air through a narrow orifice located just
forward of the wing flap leading edge. This latter
method is used on the T - 1 aircraft. ( Review
NavPers 10307-C , Airman . )
LANDING GEAR
RETRACTABLE TYPE
The landing gear of fixed -wing aircraft
consists of main and auxiliary units. For land
based aircraft and amphibians, two main wheels
Figure 4-9 . - Types of spoilers. AM.240
are placed side by side under the wings or under
the fuselage, and an auxiliary wheel is located
66
either under the nose or tail . If the aircraft is with hydraulic fluid and compressed air or
designed for carrier operations, an arresting gear
> nitrogen. Figure 4-11 shows the internal
(hook ) is also provided . When amphibians are construction of a shock strut .
operating from water , the hull provides The telescoping cylinders, known as cylinder
buoyancy , but because of the large wingspan , and piston , when assembled , form an upper and
wingtip floats are needed to provide stability at lower chamber for movement of the fluid . The
low speeds . lower chamber ( piston ) is always filled with
The landing gear of the earliest aircraft fluid , while the upper chamber ( cylinder)
consisted merely of protective skids attached to contains compressed air or nitrogen . An orifice
the lower surfaces of the wing and fuselage. As is placed between the two chambers through
aircraft developed, skids became impractical, which fluid passes into the upper chamber
and were replaced by a pair of wheels placed during compression and returns during extension
side by side ahead of the center of gravity with a of the strut . The size of the orifice is controlled
tail skid supporting the aft section of the by the movement of a tapered metering pin up
aircraft. The tail skid was later replaced by a and down through the orifice.
swiveling tailwheel. This arrangement was Whenever a load comes on the strut due to
standard on all land -based aircraft for so many landing or taxiing and compression of the two
years that it became known as the conventional strut halves starts , the piston (to which wheel
type landing gear . As the speed of aricraft and axle are attached) forces fluid through the
increased , the elimination of drag became orifice into the cylinder, where the rising fluid
increasingly important . This led to the develop level compresses the air or nitrogen above it.
ment of retractable landing gear . When the strut has made sufficient stroke to
Just before World War II , new aircraft were absorb the energy of the impact , the air or
designed with the main landing gear located nitrogen at the top expands and forces the fluid
behind the center of gravity and an auxiliary back . The slow metering of the fluid acts as a
gear under the nose of the fuselage. This became snubber , preventing rebounds. Instructions for
known as the tricycle type landing gear , and in servicing shock struts with hydraulic fluid and
many ways , it is a big improvement over the compressed air or nitrogen are contained on an
conventional type . The tricycle gear is more instruction plate attached to the strut , as well as
stable in motion on the ground, maintains the in the Maintenance Instructions Manual for the
fuselage in a level position which increases the type aircraft involved . The shock absorbing
pilot's visibility and control , and also makes qualities of a shock strut are heavily dependent
landing easier , especially in cross winds. Nearly on maintenance of proper air or nitrogen
all present -day Navy aircraft including amphi pressure and fluid level . ( Shock strut servicing is
bians are equipped with this type landing gear. covered in chapter 12. )
RETRACTING MECHANISMS . - Some air
Main Landing Gear craft have electrically actuated landing gear but
most are hydraulically actuated . In figure 4-10 ,
A main landing gear assembly is shown in the retracting mechanism is hydraulically
figure 4-10. The major components of the actuated and consists of an actuating cylinder,
assembly are shock strut, tire , tube , wheel , UP position and DOWN position locks , a safety
retracting and extending mechanism , and side switch , two position-indicating switches, and
struts and supports. Tires, tubes, and wheels are
9 side struts and supports. The landing gear
discussed in chapter 9. A description of the control handle in the cockpit allows the landing
major components follows. gear to be retracted or extended by directing
The shock strut absorbs the shock that hydraulic fluid under pressure to the actuating
otherwise would be sustained by the airframe cylinder. The locks hold the gear in the desired
structure during takeoff, taxiing, and landing. position and the safety switch prevents ac
The AIR-OIL type shock strut is used on all cidental retracting of the gear when the aircraft
Navy aircraft. This type strut is composed is resting on its wheels.
essentially of two telescoping cylinders filled A position indicator on the instrument panel
67
2
2
‫دالد‬
‫لل‬‫ل‬
GEAR UP
‫للال‬
‫ܝ‬
‫ܠܠܠܠܠܜ‬
4 5 6 GEAR DOWN
7
8
9
15 10
14 11
13
12
Ei
AM.241
1. Side strut bearing support 9. Shock strut
2. Truss member. 10.. Safety switch .
3. Fulcrum bearing support. 11 . Torque arms.
4. Spring-loaded cartridge. 12 . Towing eye.
5. Hydraulic actuating cylinder. 13. Brake assembly .
6. Downlock assembly. 14. Lower side strut member .
7. Air valve. 15 . Upper side strut member.
8. Piston rod attachment fitting.
Figure 4-10.-Main landing gear assembly .
68
Nose Gear
A typical nose gear assembly is shown in

AIR VALVE
figure 4-12. Major components of the assembly
include shock strut, drag struts , retracting
mechanism, wheel , tire, tube, and shimmy
damper .
OUTER The nose gear shock strut , drag struts, and
CYLINDER retracting mechanism are all similar to those
already described for the main landing gear.
-METERING PIN
The shimmy damper is a self- contained hy
draulic unit which resists sudden twisting loads
applied to the nosewheel during ground opera
ORIFICE PLATE tion but does permit slow turning of the wheel.
(See fig. 4-12 . ) The primary purpose of the
shimmy damper is to prevent the nosewheel
nominio
from shimmying (extremely fast left -right

TORQUE
oscillations) during takeoff and landing. This is
ORIFICE
ARMS accomplished by the metering of hydraulic fluid
through a small orifice between two cylinders or
chambers.
Some aircraft are equipped with steerable
INNER nosewheels and do not require a separate self
CYLINDER
( PISTON ) contained shimmy damper. In such cases, the
WHEEL AXLE steering mechanism is hydraulically controlled
and incorporates two spring-loaded hydraulic
TOWING EYE steering cylinders which , in addition to serving
as a steering mechanism , also automatically
>
subdue shimmy and center the nosewheel.
Tail Gear
The tail gear assembly consists of a shock

strut, retracting mechanism , wheel , tire , yoke ,
>
centering mechanism , and locking mechanism ,

AM.242 The shock strut and retracting mechanism are
Figure 4-11 . - Shock strut, showing internal construction . similar to those described for the main landing
gear .
The wheel is usually equipped with a solid
rubber tire; however
however,, some aircraft use a
indicates the position of the landing gear to the pneumatic tire on the tail wheel . The yoke
pilot . The position indicator is operated by the usually consists of a fork or single arm of
position -indicating switches mounted on the UP aluminum or steel, which link the wheel axle
and DOWN locks of each landing gear. with the shock strut . The centering mechanism
EMERGENCY EXTENTION .-Methods of causes the tailwheel to caster to the trailing
extending the landing gear in the event of position during ground handling of the aircraft.
normal system failure vary with different models It consists of a spring assembly which forces a
of aircraft. Most aircraft utilize an emergency roller against a cam mounted on top of the
hydraulic system . All others are pneumatic shock strut inner cylinder.
(compressed air or nitrogen), mechanical, The locking mechanism is independent of the
gravity, or a combination of these systems . centering mechanism and is operated by a
69
3
1
T nd
A HU Pi : 18 %
13
GEAR UP
7
14 .
10
11
12
GEAR DOWN
AM.243
1. Hydraulic actuating cylinder. 8. Cam.

2. Downlock switch. 9. Lower drag strut member.
3. Uplock cylinder. 10. Uplock engagement fitting.
4. Uplock switch . 11 . Piston-axle.
5. Uplock. 12. Torque arms.
6. Upper drag strut Shock strut cylinder.
13.
7. Downlock. 14. Shimmy damper.
Figure 4-12 . - Nose gear assembly.
control cable system connected to the tailwheel is used only during takeoff and landing. When
lock control lever in the cockpit . When the the control lever is placed in UNLOCK , the tail
control lever is in LOCK position , the tailwheel wheel is free to swivel. This position must be
is locked in the trailing position . LOCK position used for taxiing and all other ground handling
70
PRIMARY
RELEASE DASHPOT
CABLE BOTTLES
DASHPOTS
ARRESTING
HOOK
BUMPER
ARRESTING
HOOK
ASSEMBLY
EMERGENCY
RELEASE CABLE
AM.244
Figure 4-13. -Arresting gear installation.
operations . FAILURE TO OBSERVE THIS hook , and conduct specified inspection and
CAN RESULT IN SERIOUS STRUCTURAL regular replacement of hook points. Removed
DAMAGE . hooks are forwarded to the nearest naval air
station that provides Depot maintenance
Arresting Gear support for inspection , test , and overhaul .
The arresting gear shown in figure 4-13

consists of an arresting hook and its control Tail Skag
mechanism . The hook generally consists of a
steel shank and detachable steel point . The Most aircraft having a tricycle type landing
control mechanism is hydraulically operated . It gear are equipped with a tail skag to protect the
is similar to the retracting mechanism for the aft fuselage section from damage while landing,
landing gear, but is operated independently of taxiing , or while being serviced .
the landing gear by a separate control in the The tail skag consists of a steel shoe or solid
cockpit. On some aircraft the arresting gear is wheel , a conventional air-oil shock strut, retract
electrically operated . ing mechanism , and attachment fittings. The
The aircraft arresting gear is a critical part of retracting mechanism operates simultaneously
the aircraft equipment . In keeping with this with the landing gear mechanism so that when
importance , operating activities are required to the landing gear is lowered the tail skag is
maintain the appropriate logs, including the lowered , and when the landing gear is retracted
number of arrested landings on every arresting the tail skag is retracted. Some aircraft are
71
equipped with a stationary bumper in place of a the ground (hover). No runway is required for a
retractable tail skag. helicopter to takeoff or land . The roof of an
office building is an adequate landing area . The
helicopter is considered a safe aircraft because
ROTARY-WING AIRCRAFT the takeoff and landing speed is practically zero.
As will be noticed during study of the
The history of rotary -wing development following section concerning the construction of
embraces 500 - year old efforts to produce a helicopters, they are in many ways similar to
workable direct -lift-type flying machine . Man's fixed -wing aircraft. The chapter concludes with
early experiments in the helicopter field were a brief study of helicopter theory of flight.
fruitless. It is only within the last 30 years that
encourgaging progress has been made , and it is FUSELAGE
within the past 20 years that production line
helicopters have become a reality . Today, Like the fuselage in fixed -wing aircraft,
helicopters are found throughout the world , helicopter fuselages may be welded truss or
performing countless tasks especially suited to some form of monocoque construction . The
the unique capabilities of the modern -day welded truss fuselages predominate in the very
version of the dream envisioned centuries ago by small one- and two-place “ choppers." Larger
Leonardo da Vinci . helicopters, characteristic of those designed for
Da Vinci , who is recognized as the “ Father of the military, run to the monocoque design .
the Helicopter , " made a series of drawings, with A typical Navy helicopter, the H-3 aircraft
proper notations, which introduced the direct built for the Navy by Sikorsky Aircraft, is
lift principle of flight. The da Vinci Helix (as he illustrated in figure 4-14. A flying boat type hull
termed his craft ) was a spiral wing on a vertical provides this helicopter with water -operational
shaft. It embodied the basic principles of the capabilities for emergencies only . The fuselage
present-day helicopters . Da Vinci claimed that consists of the entire airframe from the forward
air had substance ( we call it density ) , and that a fuselage to the tail pylon. A cabin area occupies
spiral wing device, if turned at a sufficiently high most of the forward fuselage not used for the
speed , would bore up into the air much in the flight deck (pilot and copilot compartment ).
same fashion as an auger bores into wood . The fuselage areas are sometimes known as the
Early in the development of rotary -wing body group as is the case in the H-3 .
aircraft, a need arose for a new word to The body group is of all metal semi
designate this direct- lift flying device , and a monocoque construction , consisting of
resourceful Frenchman seized upon the two aluminum alloy and titanium skin panels cover
words , “ Helis” which means screw or spiral, and ing a reinforced aluminum alloy framework or
“ Pteron ” which means wing. Combining these skeleton . The skeleton of the lower fuselage
two words he fashioned the word " helicopter," consists of bulkheads , frames, and formers sup
which should be pronounced " hell-i-cop -ter .' ported longitudinally ( fore and aft) by a keel
A helicopter employs one or more power beam, chine angles , longerons , and stringers. The
driven horizontal air screws or rotors from skeleton of the remainder of the body group
which it derives lift and propulsion . If a single consists of bulkheads and frames, which form
rotor is used , it is necessary to employ a means the crosssectional shape, and longerons, inter
to counteract torque . If more than one rotor is costals (between rib stiffeners), and stringers
used , torque can be “ washed out” effectively by which form the longitudinal contour .
turning a combination of rotors in opposite
directions. LANDING GEAR GROUP
The fundamental advantage the helicopters
has over conventional aircraft is that lift and The landing gear group includes all the equip
control are relatively independent of forward ment necessary to support the helicopter when
speed. A helicopter can fly forward , backward, not in flight - conventional landing gear consist
or sideways, or remain in stationary flight above ing of a right- and left-hand main landing gear
72
NAVY
AM.245
Figure 4-14. -H-3 helicopter.
and a nonretractable tail landing gear plus right Retractable alighting gear is not a feature
and left-hand sponsons which house the main common to all helicopters, nor even a majority
landing gear during flight and aid in stabilizing of them . The H-3 is discussed here because it is
the aircraft during emergency operation from one of the Navy's latest helicopter designs and it
water when the aircraft is floating. has the emergency water operational capability.
The H-3 is illustrated in figure 4-14. Note the
Main Landing Gear boat-shaped hull and the sponsons with landing
gear extended from them . Most other heli
Each main landing gear is composed of a copters have fixed tricycle alighting gear or a
shock strut assembly , dual wheels, a retracting dual sled -like skid arrangement which eliminates
cylinder, an uplock cylinder, and upper and the necessity for a nose or tail support.
lower drag braces. The wheels retract into a well
recessed into the underside of the sponsons. The
dual wheels, equipped with tubeless tires and Tail Landing Gear
hydraulic brakes, are mounted on axles which
are part of the lower end of the shock strut The H-3 tail landing gear is nonretractable and
piston . full swiveling and serves as an aft touch -down
Normally, the main landing gear is extended point for land -based operations only. An air oil
hydraulically. However, in the case of hydraulic type shock absorber unit, hinged to the yoke
failure, an emergency system of compressed air and shaft, cushions the landing shock . All
may be used to lower the gear. Should the air components, with the exception of the axle and
system fail, a valve , actuated by the pilot , allows the shock absorber, are made from 7075 - T6
the gear to fall of its own weight. aluminum alloy forgings.
73
9.
10
II
12 2 3
AM.246
1. Cuff. 7. Tip pocket.
2 Plate. 8. Tip cap.
3. Spar . 9. Abrasion strip.
4. Root pocket cap . 10. Abrasion strip .
5. Root pocket. 11 . Ice guard.
6. Pocket (typical). 12. Bracket
Figure 4-15 . - Typical rotary wing blade.
MAIN ROTOR ASSEMBLY blade is attached to the hub . The main support
ing member of the blade is a hollow , aluminum
The main rotor ( rotary wing) and the rotor alloy extruded spar which forms the leading
head are discussed in this section under the one edge . The steel cuff is bolted to the root end of
heading because their functions are so closely the spar .
related . Neither has a function without the Twenty - three individual pockets , each
other . constructed of aluminum ribs , an aluminum
channel , and aluminum skin covering, are
Rotary Wing bonded to the aft edge of the spar. The tip end
of the blade contains a readily removable tip
The main rotor or rotary wing of the H-3 is cap, fastened to the spar and tip pocket rib by
comprised of five identical wing blades. Other means of screws . The root pocket of the blade is
types of helicopter rotors may have two , three, sealed at its inboard end by an aluminum alloy
or four blades . A typical wing blade is illustrated root cap , cemented and riveted to the pocket .
in figure 4-15 . A stainless steel abrasion strip is bonded to
The rotary wing blade illustrated in figure the leading edge of the spar from blade pocket
4-15 is fabricated of aluminum alloy, with the No. 8 and extends along the entire leading edge ,
exception of the forged steel cuff by which the including the tip cap . Also, the blade illustrated
74
is fitted with a deicing guard . The guard is

composed of fine wire braid heating elements,
interwoven in bands and embedded in a rubber
strap to which is bonded a stainless steel strap .
The guard is bonded to the leading edge of the
spar and is molded to the contour of the blade .
2
5
Rotor Head
The rotary wing head is splined to , and >
supported by , the rotary wing shaft of the main

gearbox. The head supports the rotary wing
blades, is rotated by torque from the main
gearbox , and transmits movements of the flight
controls to the blades.
The principal components of the head are the
hub and swashplate. The hub consists of a hub
plate and lower plate ; hinges , between each arm
of the plates ; sleeve-spindles which are attached AM.247
1. Pitch link.
to the hinges ; and a damper-positioner for each 2 Rotary rudder blade.
wing blade. The swashplate consists of a rotating 3. Spindle.
swashplate and stationary swashplate . Other 4. Pitch control beam.
components of the rotary wing head are anti 5. Rotary rudder hub.
flapping restrainers, droop restrainers, adjustable 6 Pylon.
pitch control rods, and rotating and stationary Figure 4-16.-Tail rotor group.
scissors .
The swashplate and adjustable pitch control
rods permit movement of the flight controls to aircraft with directional control . These are
be transmitted to the rotary wing blades. The pylon, rotary rudder blades, and rotary rudder
hinges allow limited movement to the blades in head . The rotary rudder head includes such
relation to the hub . These movements are items as the hub , spindle , and pitch control
known as LEAD, LAG , and FLAP. LEAD beams.
occurs during slowing of the drive mechanism
when the blades have a tendency to remain in Pylon
motion . LAG is the opposite of LEAD and
occurs during acceleration when the blade has The pylon illustrated in figure 4-16 is of
been at rest and tends to remain at rest . FLAP is aluminum semimonocoque construction , and is
the tendency of the blade to rise with high lift composed of beams, bulkheads, stringers,
demands as it tries to screw itself upward into formers, and channels . Various gages of alumi
the air. The damper-positioners restrict lead and num skin located on the left- and right-hand
lag motion and position the blades in prepara sides of the box structure are part of the
tion for folding. Sleeve-spindles allow each blade primary pylon structure . Reinforced plastic fair
to be rotated on its spanwise axis to change the ings in the leading and aft surfaces forming the
blade pitch . The anti-flapping restrainers and airfoil contour of the pylon are considered to be
droop restrainers restrict flapping motion when secondary structure .
the rotary wing head is slowing or stopped. The pylon houses an intermediate gearbox
and the tail gearbox . The pylon is attached on
TAIL ROTOR GROUP the right side of the aircraft to the main fuselage
by hinge fittings. These hinge fittings also serve
The tail rotor group (fig. 4-16) is comprised as the pivot point for the pylon to fold alongside
of those helicopter components that provide the the right side of the rear fuselage. Folding of the
75
pylon reduces the overall length of the H-3 principles involved in the aerodynamics of flight.
helicopter by 7 1/2 feet, thereby greatly facili Instead , there is but brief mention of the
tating its handling, particularly aboard ship. principles themselves , with the major emphasis
on their application to the helicopter.
Rotary Rudder Head Although in many respects the helicopter
differs radically from the conventional aircraft,
The rudder head , usually located on the left rotary -wing aerodynamics is not something
side of the pylon , produces anti-torque forces entirely new and different from fixed -wing
which may be varied by the pilot to control aerodynamics. The same basic principles apply
flight heading. The rotary rudder head is driven to both aircraft. During flight, the two types of
by the tail gearbox. Change in blade pitch is aircraft are subjected to many of the same forces
accomplished through the pitch change shaft and affected by many of the same reactions. In
that moves through the horizontal shaft of the short , the principles involved in rotary-wing
tail gearbox. As the shaft moves inward toward aerodynamics are those basic principles with
the tail gearbox , pitch of the blade is decreased . which the Aviation Structural Mechanic S Third
As the shaft moves outward from the tail Class or Striker has already learned while
gearbox, pitch of the blade is increased . The preparing himself for advancement to Airman .
pitch control beam is connected by links to the In flight, both conventional aircraft and the
forked brackets on the blade sleeves. helicopter are acted upon by four basic forces-
A flapping spindle for each blade permits WEIGHT, LIFT, THRUST, and DRAG . In ad
flapping of the blade to a maximum of 10 dition , both types of aircraft are affected by
degrees in each direction . torque reaction .
LIFT . -Weight and lift are closely related in
Rotary Rudder Blades that weight tends to pull the aircraft - or
helicopter- down, and lift holds it up . Right
The blades are on the rotary rudder head . here is where the basic similarity between the
Each blade consists of an aluminum spar, an helicopter and the airplane begins ; both aircraft
aluminum pocket with honeycomb core , an are heavier than air and both are supported by
aluminum tip cap, an aluminum trailing edge the reactions of airfoils to air passing over them .
cap , and an abrasion strip . In addition , those This reaction , or lift, is a result of pressure
blades that have de -icing provisions have a differential. The pressure on the upper surface
neoprene anti-icing guard , embedded with elec of the supporting airfoil is less than atmospheric,
trical heating elements. The root end of the while the pressure on the lower surface is equal
blade permits attaching to the rotary rudder to , or greater than , atmospheric.
head spindles. The abrasion strip protects the The conventional aircraft's airfoils are, of
leading edge of the blade, or the de -icing guard , course , the wings. The helicopter's airfoils are
from sand , dust, and adverse weather conditions. the rotor blades. One aircraft has fixed wings
The skin is wrapped completely around the spar, and the other rotary wings, but the same basic
and the trailing edge cap is installed over the principles of lift apply to both.
edges of the skin at the trailing edge of the The length , width , and shape of an airfoil all
blade . The tip cap is riveted to the outboard end affect its lifting capacity. However, for any one
of the blade . airfoil there are but two primary factors affect
ing the amount of lift the airfoil will develop .
THEORY OF FLIGHT The relation between these two factors - velocity
of airflow and angle of attack -and their effect
At this point it is assumed that the AMSAN on lift can be expressed as follows:
or AMS3 who is studying for advancement in For a given angle of attack , the greater the
rating is familiar with theory of flight and its speed , the greater the lift.
application to fixed -wing aircraft. ( Review Nav For a given speed , the greater the angle of
Pers 10307 -C , Airman .) Therefore, this chapter attack (up to the stalling angle), the greater the
contains no extended discussion of the basic lift.
76
Thus, lift can be varied by varying either one

of these two factors. Furthermore, increasing
either speed or angle of attack , or both, (up to
DET
certain limits) increases lift.
CHORD PLANE OF AIRFOIL
Velocity of Airflow . - Not only is velocity of WIND
airflow a primary factor affecting lift , but a

certain minimum velocity is required in order CHORD PLANE OF AIRFOIL CHORDS
that the airfoils may develop sufficient lift to get

either an airplane or a helicopter into the air and
keep it there . This means that for either the
airplane or the helicopter , the airfoils must be
moved through the air at a relatively high speed .
In the conventional aircraft the required flow
of air over the airfoils can be obtained only by
moving the entire aircraft forward . If the wings
must move through the air at 100 miles per hour
to produce sufficient lift to support the aircraft AM.248
in flight, then the fuselage and all other parts of Figure 4.17. -Chord planes of airfoils .
the aircraft must move forward at that same
speed. This means that the aircraft must takeoff,
fly, and land at relatively high speeds . Further With the conventional aircraft , the angle of
>
more , it means that the aircraft is limited to attack can be varied only by changing the
forward flight; it cannot fly backwards or attitude of the entire aircraft ( F-8 excepted ) .
sideways. When , for example , the pilot wishes to climb, he
The helicopter's airfoils must also move pulls back on the control stick or column so that
through the air at comparatively high speed to the aircraft will take a nose -high attitude ,
produce sufficient lift to raise the aircraft off thereby increasing both angle of attack and lift.
the ground or keep it in the air. But here, the When he reaches the desired altitude , he levels
required speed is obtained by rotating the off to decrease the angle of attack . When he
airfoils. Furthermore, the rotor can turn at the wishes to descend , he pushes forward on the
required takeoff speed while the fuselage speed stick or column , causing the aircraft to take a
remains at zero . nose- low attitude.
Thus, the speed of the airfoils (rotor blades), The pilot can increase or decrease the heli
and the resultant velocity of airflow over them , copter's angle of attack without changing the
is independent of fuselage speed . As a result , the
> attitude of the fuselage. He does this by
helicopter does not require high forward speeds. changing the pitch of the rotor blades by means
of the entire aircraft for takeoff, flight, and of a cockpit control provided for this purpose.
landing. Nor is it limited to forward flight. It can In fact, under certain flight conditions, the angle
rise vertically . It can fly forward , backward , or of attack continually changes as the rotor blade
sideways as the pilot desires. It can even remain turns 360 degrees. This occurs whenever the
stationary in the air while the rotating airfoils rotor plane of rotation is tilted , as it is during
develop sufficient lift to support the aircraft . In forward , backward , and sideways flight. This
fact, all of these kinds of flight are normal for tilting of the plane of rotation of the main rotor
the helicopter . and the aerodynamics of the various kinds of
Angle of Attack.- Velocity of airflow around flight are discussed later. (Plane or rotation is
an airfoil is but one of the factors affecting lift. also known as the tip path plane and includes
The other factor is angle of attack . For either an that area swept by the rotating blades.)
airplane wing or a helicopter rotor blade , the
> Angle of Incidence . -For the airplane, the
angle of attack is the angle formed by the chord final value of the angle of attack depends on the
plane of the airfoil and the relative wind , as attitude of the airplane and one other factor
shown in figure 4-17. the angle of incidence. The angle of incidence,
77
FIXED ANGLE
LONGITUDINAL AXIS
WIND
LONGITUDINAL AXIS
VARIABLĘ ANGLE VARIABLE ANGLE
AM , 249
Figure 4-18 . - Angles of incidence.
for either an airplane or helicopter, is the angle An unsymmetrical airfoil may be efficient for
formed by the chord of the airfoil and the an airplane wing, but it has one disadvantage
longitudinal axis of the aircraft. The longitudinal that makes it unsatisfactory for use as a rotor >
axis of a helicopter is aa line at right angles to the blade . The center of pressure “ walks” forward
main rotor drive shaft.
The conventional aircraft's angle of incidence
is determined by the designer and is built into
the aircraft. The angle of incidence cannot be UNSYMMETRICAL AIRFOIL
changed by the pilot .
The helicopter's angle of incidence can be ((COCO ) ) )
changed at will by the pilot - by changing the
pitch of the rotor blades. Like the angle of WIND
CENTER OF
attack ,, the angle of incidence continually PRESSURE TRAVEL
changes as the rotor revolves whenever the SYMMETRICAL AIRFOIL
control stick is moved from the neutral position
and the rotor plane of rotation is tilted . Note
the comparative angles of incidence, as sketched
in figure 4-18 .
AIRFOIL SECTION . - Airfoil sections used CENTER OF
PRESSURE FIXED
for airplane wings vary considerably - each being
selected to meet specific requirements. The
airfoil may be symmetrical or unsymmetrical , AM.250
like the ones shown in figure 4-19 . Figure 4.19 . - Center of pressure.
78
and rearward as the angle of attack changes. The within the rotor system.
center of pressure is an imaginary point on the During vertical ascent , thrust acts vertically
airfoil where all of the aerodynamic forces are upward while drag acts vertically downward .
considered as being concentrated . On an un Here the drag opposing the upward motion of
symmetrical airfoil the center of pressure is the helicopter is increased by the down-wash of
toward the rear of the wing at small angles of air from the main rotor. Thrust must be suf
attack and moves forward as the angle of attack ficient to overcome both of these forces which
is increased. This forward movement continues make up the total drag. In the illustration ( fig.
until the angle of attack is approximately the 4-20) , note that thrust acts in the same direction
same as the angle of maximum lift coefficient. and in line with lift. Furthermore, the main
( The angle of maximum lift coefficient is that rotor is responsible for both thrust and lift .
angle at which 1 square foot of airfoil travelling Therefore, the force representing the total re
at 1 mile per hour will produce the greatest action of the airfoils to the air may be con
possible lift.) sidered as being divided into two components.
The center of pressure cannot be permitted to One component , lift, is the force required to
walk back and forth on a helicopter rotor blade, support the weight of the helicopter. The other
since shifting of the center of pressure would component , thrust , is the force required to
introduce pitch -changing forces. This would be overcome the drag on the fuselage . But drag is a
undesirable - and dangerous. Therefore, the separate force from weight , as is indicated in
center-of-pressure travel is controlled by airfoil figure 4-20.
design and is usually at a point 25 percent back Now let us examine the thrust and drag forces
from the leading edge of the rotor blade . A acting on the fuselage during forward flight.
symmetrical airfoil has the desirable charac In any kind of flight - vertical, forward , back >
teristic of limiting center -of -pressure travel . ward , sideways, or hovering- the resultant lift
THRUST AND DRAG . - Like weight and lift,
-
thrust and drag are closely related . Thrust moves

the aircraft in the desired direction ; drag tends
to hold it back . THRUST
The conventional aircraft's thrust is , in
general , forward , and drag to the rear. These 1
LIFT
forces always act in opposite directions and are
usually horizontal, or only slightly inclined from 1
the horizontal. Seldom , if ever , do these forces
approach the vertical . Furthermore, the con
ventional aircraft's thrust can be separated and
considered apart from lift. The propeller (or jet)
is responsible for thrust ; the wings are respon
sible for lift.
The helicopter gets both its lift and thrust
from the main rotor . In vertical ascent , thrust
acts upward in a vertical direction, while drag,
the opposing force, acts vertically downward . In
forward flight, thrust is forward and drag to the DRAG
rear. In rearward flight, the two are reversed . In

short, thrust acts in the direction of flight and
drag acts in the opposite direction . WEIGHT
The thrust and drag forces and two of these
conditions - vertical flight and forward flight
are discussed in the following paragraphs. These AM.251
discussions deal with the thrust and drag forces Figure 4-20 . - Alignment of forces during
acting on the fuselage , not with the forces vertical ascent.
79
RESULTANT LIFT LIFT RESULTANT

LIFT
↑
thhutt
소 THRUST
DRAG
WEIGHT
AM.252
Figure 4-21. - Transition from vertical to forward flight.
forces of a rotor system are perpendicular to the one direction , the fuselage tends to rotate in the
tip path plane ( plane of rotation ). Remember, opposite direction . This torque effect is in
the tip path plane is the imaginary plane accord with Newton's third law of motion which
described by the tips of the blades in making a states that , “ To every action there is an opposite
cycle of rotation . During vertical ascent or and equal reaction . ” In the helicopter , the
hovering, the tip path plane is horizontal and reaction is in a direction opposite to that in
this resultant force acts vertically upward , as which the rotor is driven by the engine and is
shown in figure 4-21. To accomplish forward proportional in magnitude to the power being
flight, the pilot tilts the tip path plane forward . delivered by the engine.
The resultant force tilts forward with the rotor Torque is of real concern to both the designer
as shown in the illustration . The total force , now and pilot . There must be provisions for counter
being inclined from the vertical , acts both acting torque and for positive control over its
upward and forward ; therefore, it can be
> effect during flight. On dual-rotor and coaxial
resolved into two components as shown in the rotor helicopters, the rotors turn in opposite
illustration . One component is lift , which is directions, thus “ washing out ” torque reaction.
equal to and opposite weight. The other In jet helicopters with engines mounted on the
component , thrust, acts in the direction of flight main rotor blade tips, the power is initiated at
to move the helicopter forward . the rotor blade ; therefore, the reaction is
Although this discussion covers only two between the blade and the air, with no torque
flight conditions, it should point the way to a reaction between the rotor and the fuselage.
basic understanding of thrust and drag forces Therefore, it is in helicopters of the single main
acting on the helicopter fuselage during flight. In rotor configuration that torque presents a
rearward flight, the thrust and drag forces are problem to the pilot during flight.
similar to those in forward flight, but are The usual way of counteracting torque in a
reversed. The tip path plane is tilted to the rear, single main rotor helicopter is by means of an
the thrust component acts to the rear , and drag antitorque rotor. This axuiliary rotor is mounted
opposes the rearward motion of the aircraft . In vertically on the outer portion of the tail boom .
sideways flight, the pilot tilts the tip path plane Turning at a constant rpm , usually slightly
in the desired direction of flight, thrust is to the higher than one -half engine speed , the tail rotor
right or left in the direction of flight, and drag produces thrust in a horizontal plane , opposite
acts in the opposite direction . in direction to the torque reaction developed by
TORQUE. -As the helicopter rotor turns in the main rotor. Figure 4-22 shows the direction
80
means of heading the helicopter in the desire

direction of flight. Therefore, the tail roto
control pedals serve as rudder pedals. The effec
of the tail rotor controls is shown in figure 4-23
Applying left rudder causes the nose of th
helicopter to turn to the left ; applying righ
rudder causes the nose to swing to the righ
When the pilot wishes to maintain a constan
heading , he keeps just enough pitch in the ta
rotor to neutralize torque effect.
Although the tail rotor is the primary mean
of counteracting and controlling torque , the ta
rotor alone does not quite do the job . This
ROTOR BLADE
ROTATION true because torque cannot be compensated fo
by a single force. The tail rotor alone woul
prevent rotation of the fuselage, but woul
cause TRANSLATION (movement in a latera
direction ) of the helicopter, during hovering , i
the direction of tail rotor thrust.
Complete compensation for torque requires
TAIL ROTOR THRUST COUPLE - a pair of equal forces acting in op
-
DIRECTION
OF TORQUE
TO COMPENSATE posite directions . Tail rotor thrust constitute
FOR TORQUE one of the forces. The second force i
introduced by rigging the helicopter with the ti
path plane tilted from 1 to 2 1/2 degrees to th
AM.253 left, depending upon the helicopter. Figure 4-2
Figure 4-22 - Torque reaction and compensation. shows the balance of forces on a helicopte
employing a single right-to -left main rotor. Not
that the slight tilt of the tip path plane to th
left results in a thrust force to the left. Thi
of the torque reaction and the direction of tail force and tail rotor thrust form the coupl
rotor thrust for a helicopter in which the main required to completely compensate for torque
rotor turns from the pilot's right, to his front, to
his left, and then to his rear. Most single rotor Hovering
systems turn in this direction .
Since the torque effect on the fuselage is a Hovering is the maintaining of a positio
result of the engine power supplied to the main above a fixed spot on the ground , usually at a
rotor, any change in engine power brings about a altitude of about 8 feet. Helicopters normall
corresponding change in the torque effect. hover on takeoffs and landings .
Furthermore, power requirements vary with For the helicopter to hover, its main rot
flight conditions. Therefore , the torque effect is must supply lift equal to the helicopter's weigh
not constant but varies during flight. This means Lift is controlled by controlling the pitch of th
that there must be some provision for varying rotor blades. As the blades rotate, air flow
tail rotor thrust. Usually , a variablepitch tail across the leading edge of each blade in th
rotor is employed and rudder pedals are linked direction indicated in figure 4-25 . The airflo
by cables with the pitch change mechanism in crosses the leading edge of each blade througl
the tail rotor head . This permits the pilot to out the complete rotational cycle of 36
increase or decrease tail rotor thrust, as required,
> degrees. At the same time the blades have
to neutralize the torque effect. tendency to screw upward into the air , and a
The tail rotor and its controls serve as both a flows down through the rotor system froi
means of counteracting torque effect and a above as shown in figure 4-26 .
81
" TO 2-1/ 2 " TILT
T
NOSE
LEFT
RUDDER THRUST TAIL
ROTOR
THRUST
MAIN ROTOR
ROTOR BLADE TORQUE REACTION
ROTATION
AM. 255
Figure 4-24 . -Balance of forces on a helicopter.
MAIN ROTOR TAIL ROTOR THRUST

TORQUE REACTION INCREASING
NOSE
RIGHT
RUDDER
W
LO
RF
AI
ROTOR BLADE
ROTATION
AM.256
TAIL ROTOR THRUST
Figure 4-25 . -Airflow across blades.
MAIN ROTOR
TORQUE REACTION DECREASING
The pitch and rpm of the rotor blade are

controlled by the COLLECTIVE PITCH stick .
Control by this stick affects all the blades
AM.254 collectively . The normal location of this control
is shown in figure 4-27 . By raising or lowering
Figure 4-23. - Effect of tail rotor pitch the collective pitch stick one can change the
changes on heading. collective pitch-the pitch on all of the main
82
from the bottom of the collective pitch stick to

the carburetor by a series of push-pull rods . As
the blade pitch is increased , calling for more
engine power to maintain a constant rotor rpm ,
the synchronization unit opens the throttle. The
opposite is also true, of course . If the blade
pitch is decreased, less engine power is required
www
Somew
for the same rotor rpm, so the synchronization
unit acts to reduce engine power.
On the upper end of the collective pitch stick
is a motorcyclegrip type throttle, with which the
throttle can be rolled on " or "rolled off” if the
synchronization unit does not maintain exact
engine rpm . This hand throttle permits over
riding of the synchronization unit in making the
final adjustments to obtain the specified engine
rpm .
AM . 257 Directional Flight

Figure 4-26 . - Airflow through blades.
Directional flight of a helicopter demands
pilot coordination to properly execute the
desired flightpath . The helicopter can fly either
vertically , horizontally , or a combination of the
two directions. Both vertical and horizontal
flight are discussed in the following paragraphs.
CYCLIC CONTROL STICK
VERTICAL FLIGHT . - Vertical flight is con
TOT . trolled exactly the same way as hovering, since
hovering is an element of vertical flight. To
climb , the collective pitch stick is raised , using
the throttle on the pitch stick to make any rpm
COLLECTIVE PITCH
STICK WITH MOTORCYCLE
adjustments not made automatically . At the
GRIP TYPE THROTTLE same time , the cyclic control (discussed under
“ Horizontal Flight ”) is held in a vertical posi
tion , so that lift will be vertical . The flow of air
MB
CLI
DES
CEN
D is still over the leading edge of each blade , but
the helicopter is now moving upward as shown
in figure 4-28 .
When the helicopter is climbing vertically the
main rotor supplies not only the lift necessary to
AM.258 support the helicopter's weight, but also the
Figure 4-27 . - Main rotor pitch controls . thrust necessary to cause the helicopter to rise
vertically . To descend, the collective pitch stick
is lowered to decrease main rotor pitch and the
rotor blades - the same amount . Raising the stick resultant lift.
increases the pitch ; lowering it decreases the HORIZONTAL FLIGHT. -Horizontal flight is
pitch. If the rotor rpm remains constant , in controlled by tilting the tip path plane in the
creasing or decreasing the blade pitch causes the direction of desired flight - forward , backward ,
helicopter to climb or descend . to the left, or to the right. As detailed in figure
To maintain constant rotor rpm during pitch 4-28 , the helicopter moves in the direction the
change, a built- in synchronization unit is linked tip path plane is tilted .
83
HIGH FLAP
LOW PITCH RESULT
APPLIED
LIT
SHRUST
LOW FLAP HIGH PITCH

RESULT APPLIED
VERTICAL FLIGHT
AM.260
Figure 4-29. -Pitch changes for forward flight.
The pilot tilts the tip path plane by means of

the cyclic pitch control. This control provides a
mechanical means of changing the pitch of the
BACKWARD FLIGHT main rotor blades in any direction of tilt
throughout their full 360 degrees of rotation . Cy
clic pitch change is equal and opposite , as shown
in figure 4-29 . If the blade pitch is increased 3
degrees on one side of the rotor center, at a
point 180 degrees around the cycle of rotation,
the blade pitch is decreased 3 degrees.
For every pitch change there is a resulting
flapping action of the individual blades, as they
constantly change pitch during rotation . As is
shown , maximum flapping takes place 90
SIDEWARD FLIGHT
degrees around the cycle of rotation from the
place where the pitch change was applied. The
equal and opposite pitch change and the result
ing flapping of the individual blades causes the
tip path plane to tilt in the same direction as the
pilot moves the cyclic control stick . Thus, to fly
forward , backward, sideways, or in fact, any di
rection horizontally , all that is required is to tilt
the cyclic control stick in the desired direction .
To climb or descend while moving forward ,
FORWARD FLIGHT
backward, or to either side, is merely a matter of
coordinating the movements of the collective
pitch control , which governs vertical flight; and
AM.259 the cycle control, which governs horizontal
Figure 4-28. - Directional flight attitudes. flight.
84
CHAPTER 5
SHEET-METAL WORKING MACHINES, TOOLS,

AND PROCEDURES
TOOLS Readiness List (IMRL).

NavAir 00-35QG -016 includes all of the ac
The AMS3 and AMS2 must have a thorough countable and consumable general suppor
knowledge of the tools of his trade to enable equipment which is required for the main
him to increase his performance and the quality tenance and operation of all types of aircraft a
of his products. Using this knowledge and the Intermediate and Organizational levels o
applying it in the right direction will aid in maintenance . Most of the tools listed in NavAi
increasing the squadron's efficiency and opera 00-35QG-016 , appropriate for use by the AMS
tional availability. One of the most important are found in the toolbox he is issued .
factors that a mechanic can have is the ability to The Individual Material Readiness Lis
use the tools which are required to complete any
Individual Material
(IMRL) , which applies to an activity by name
given task in a skilled and technical manner. specifies items and quantities of aircraft ground
A mechanic is known by the tools he keeps. support equipment required for materia
The use of tools may vary ; but safety , good care , readiness of the aircraft maintained by the
and the proper stowage of tools never vary. In activity .
this chapter, some of the various tools that the Whenever the number of tools in the activity
AMS uses in the course of his duties are briefly falls below a certain minimum , the centra
>
described . The Rate Training Manuals , Tools and toolroom supervisor reorders to replenish hi
Their Uses, NavPers 10085 ( Series) , and Airman , stock . The quantity status of tools on hand i
NavPers 10307 (Series), also contain a descrip
>
determined by regular inventories.
tion of most of the tools used by the AMS,
.
together with detailed instructions for using CUSTODY

them. The material given in this chapter is
intended to supplement , rather than repeat , the When it becomes necessary or desirable for a
information given in Tools and Their Uses and AMS to have a toolbox 'assigned to him on
the Airman manuals .
custody basis, the shop supervisor will notify th
toolroom personnel to issue an AMS toolbox to
PROCUREMENT
the designated person . Normally, the centra
Some activities have a centrally located tool toolroom will have a locally prepared toolbo:
room which procures tools for the activity as a inventory form . This form will be applicable to
whole . This allows for better usage and ac the particular aircraft, equipment, and main
countability of the equipment. An activity's tenance level to be supported. They will issu
alloted amount of handtools is in accordance the toolbox in accordance with this inventor
with an allowance which is established by form , making two copies-one (master copy ) to
NavAir 00-35QG-016 , Consumable General
> be held by the central toolroom , and one to b
Support Equipment for All Types, Classes, and placed in the toolbox in a grease -resistan
Models of Aircraft, and the Individual Material envelope. The AMS should use this copy t
85
inventory his toolbox after completion of each the Illustrated Parts Breakdown ; for example ,
assigned task to insure that all of his tools have NavAir 01-75PAA -4-13 , P -3A Special Support
been placed back in his toolbox . Equipment , and NavAir 01-24FDA -4-6 , F -4A
NOTE : Reinventory of tools taken to the Special Support Equipment. When determining
jobs is a MUST to eliminate the possibility of special support equipment allowances for any
damage to the aircraft due to foreign objects left activity , refer to the Individual Material
adrift within or around the aircraft . Readiness List .
INVENTORY
HANDTOOLS
The AMS who has custody of a toolbox must
prevent the loss of tools through neglect or Before discussing the tools individually , a few
misuse. Although handtools are normally classed comments on the care and handling of handtools
as consumable items , they are very expensive in general might be appropriate . The condition
and must be paid for when lost or carelessly in which an AMS maintains his assigned tools
damaged. One method of preventing loss of determines his efficiency as well as affecting the
tools is a thorough inventory after each job judgment that his superiors pass upon him in his
assignment. Usually , the activity will have a local day-to-day work. A mechanic is always judged
instruction concerning the inventory interval heavily by the manner in which he handles his
and method of reporting lost or damaged tools. tools .
NOTE : Broken or damaged tools can damage Each mechanic should keep all his assigned
aircraft hardware and parts. They can also cause tools in his toolbox when he is not actually
personal injury to the worker or others. using them. He should have a place for every
At the periodic inventory , which is normally tool , and every tool should be kept in its place .
performed by central toolroom personnel, all All tools should be cleaned after every use and
broken or missing tools should be replaced. before being placed in the toolbox . If they are
Nonproductive time between job assignments not to be used again the same day, they should
provides ample time for further inspection and be oiled with a light preservative oil to prevent
upkeep of toolboxes. Someone has said " show rusting. Tools that are being used at a work
me a mechanic with a poor toolbox and I will bench or at a machine should be kept in easy
show you a poor mechanic ." reach of the mechanic , but should be kept where
In addition to the tools normally issued with they will not fall or be knocked to the deck .
the toolbox , there are many special tools an Tools should not be placed on finished parts of
AMS3 or AMS2 will come in contact with and machines.
use . Later in this chapter we will discuss just a
few of these tools. Special tools are normally RIVETING TOOLS
kept in the central toolroom and signed out on
an as-needed basis. These tools are returned to Rotary Rivet Cutters
the toolroom as soon as the AMS has completed
his work assignment. (Tools should be returned In case one cannot obtain rivets of the
no later than the same day as checked out .) required length , rotary rivet cutters ( fig. 5-1 ) are
Each activity has an allowance of special tools used to cut longer rivets to the desired length.
which they may have on custody . Often the When using the rotary rivet cutter , insert the
allowance for an item is only one , which means rivet part way into the correct diameter hole,
positive control must be exercised . The special place the required number of shims (shown as
tools allowance list for a particular aircraft on staggered , notched strips in the illustration )
which the AMS might be working is contained in under the head, and squeeze the handles. The
the activity's Individual Material Readiness List compound action from the handles rotates the
(IMRL) publications. two discs in opposite directions. Rotation of
Some of the newer aircraft manuals list the discs shears the rivet smoothly to give the
special tools and equipment in one section of correct length (as determined by the number of
86
Chapter 5 - SHEET-METAL WORKING MACHINES, TOOLS, AND PROCEDURES
eliminate any opening between them before

rivet is bucked . Each draw set has a hole 1
inch larger than the diameter of the rivet sh
for which it was made. Sometimes, especiall
hand working tools, the draw set and the r
header are incorporated into one tool .
header part consists of a hole sufficie
shallow for the set to expand the driven i
“ bucktail” and form aa head on it when the s
struck by a hammer. Figure 5-2 illustrate
rectangular- shaped hand set which combines
draw and header sets and a flush set used wi
pneumatic hammer .
Sets used with pneumatic hammers ( 1
guns) are provided in many sizes and shape
fit the type and location of the rivet. These
AM.290
are the same as the hand rivet sets except
the shank is shaped to fit into the rivet gun .
Figure 5.1. - Rotary rivet cutter. sets are made of high -grade carbon tool steel
are heat treated to provide the neces
shims inserted under the head ) . When using the strength and wear resistance . The tip or hea
larger cutter holes , place one of the tool handles the rivet set should be kept smooth and his
in a vise , insert the rivet in the hole , and shear it polished at all times to prevent marring of
heads .
by pulling the free handle . If this tool is not
available, diagonal cutting pliers can be used as
an emergency cutter although the sheared edges Bucking Bars
will not be as smooth and even as when cut with
the rotary rivet cutter . Bucking bars are tools used to form buck
(the head formed during riveting operations
Rivet Set rivets. They come in many different shapes
sizes, as illustrated in figure 5-3 . Bucking
A rivet set is a tool equipped with a die for are normally made from an alloy steel simila
driving a particular type of rivet. Rivet sets are
used in both hand and pneumatic hammer
riveting methods. Rivet sets are available to fit
every size and shape of rivet head . The ordinary
hand set is made of 1 / 2 -inch -diameter carbon
steel about 6 inches long and is knurled to
prevent slipping in the hand . Only the face of
the set is hardened and polished . Sets for the
oval head rivets (universal, round , and brazier)
HA
are recessed ( or cupped ) to fit the rivet head. In
selecting the correct set , be sure that it will
provide the proper clearance between the set
and the sides of the rivet head and between the
surfaces of the metal and the set . Flush or flat
sets are used for countersunk and flathead rivets.
In order to set flush rivets properly , the flush
sets should be at least 1 inch in diameter .
Special sets , called " draw " sets, are used to AM
" draw up ” the sheets being riveted in order to Figure 5-2 . - Rivet sets.
87
the ability of the AMS using it . If possible, hold

the bucking bar in such a manner that will allow
the longest portion of the bar to be in line with
the rivet. The AMS should hold the bucking bar
lightly but firmly against the end of the rivet
4 shank so as not to unseat the rivet head . The

inertia of this tool provides the force that bucks
( upsets) the rivet, forming a flat, head - like
bucktail.
Hole Finder
ANGLE SPECIAL STRINGER Ahole finder is a tool used to transfer

BUCKING FLANGE existing holes in aircraft structures or skin to
V replacement skin or patches. The tool has two
leaves parallel to each other and fastened to
gether at one end . The bottom leaf of the hole
finder has a teat installed near the end of the
leaf which is aligned with a bushing on the top
TORPEDO
DIAMOND SPECIAL leaf, as illustrated in figure 5-4. The desired hole
POINT TUBE
to be transferred is located by fitting the teat on
the bottom leaf of the hole finder into the
existing rivet hole . The hole in the new part is
made by drilling through the bushing on the top
leaf. If the hole finder is properly made , holes
drilled in this manner will be perfectly aligned .
NUT PLATE
SPECIAL DUCKBILL A separate duplicator must be provided for each
OFFSET diameter of rivet to be used .
AM.292
Figure 5-3. -Bucking bars.
tool steel . The particular shape to be used

depends upon the location and accessibility of
the rivet to be driven . The size and weight of the
bar depend on the size and type of the rivet to
be driven. Under certain circumstances, and for
specific rivet installations, specially designed AM.293
bucking bars are manufactured locally . These Figure 5-4. -Hole finder.
bars are normally made from tool steel . The
portion of the bar designed to come in contact
with the rivet has a polished finish . This helps to Skin Fasteners
prevent marring of formed bucktails . Bucking
bar faces must be kept smooth and perfectly flat There are several types of skin fasteners used
and the edges and corners rounded at all times. to temporarily secure parts in position for
NOTE : Never hold a bucking bar in a vise drilling and riveting and to prevent slipping and
unless the vise jaws are equipped with protective creeping of the parts. C - clamps, machine screws,
covers. This will prevent marring of the bucking and Cleco fasteners are frequently used in the
bar . Navy. ( See figure 5-5 .) Of the three, the Cleco is
A satisfactory rivet installation depends the most popular. Cleco fasteners come in sizes
largely on the condition of the bucking bar and ranging from 1/16 to 3/8 inch. The size is
88
Chapter 5 - SHEET-METAL WORKING MACHINES, TOOLS , AND PROCEDURES
normally stamped on the fastener, but may also spring compressed, the pin of the Cleco is
be recognized by the following color code : inserted in the drilled hole . The compressed
1/16 inch - black spring is then released, allowing spring tension
3/32 inch - cadmium on the pin of the Cleco to draw the materials
1/8 inch - copper together. Clecos should be stored on a U channel
5/32 inch - black plate to protect the pins of the Cleco . Clecos
3/16 inch- brass stores at random among heavy tools will become
1/4 inch - green useless due to bent pins .
3/8 inch - red
The Cleco fastener is installed by compressing STRIKING TOOLS
the spring with Cleco pliers (forceps ). With the
Generally speaking, this group is composed of
various types of hammers , all of which are used
to apply a striking force where the force of the
hand alone is insufficient. Each of these ham
V mers is composed of a head and a handle , even

though these parts differ greatly from hammer
to hammer .
The mallet and the ball -peen hammer (fig.
5-6) are of the most concern to the AMS and
adequate coverage on their selection , use , care,
and safety is contained in Tools and Their Uses,
HITEL NavPers 10085 (Series) , and Airman , NavPers >
10307 ( Series ), and is therefore not repeated

here .
경 BALL PEEN HAMMER

marts
희
.
PLASTIC HAMMER
M
PLASTIC FACE
AM.294 AM.23
Figure 5-5. -Skin fasteners. Figure 5-6.-Striking tools .
89
CUTTING TOOLS This lug fits into one of the notches of the nut.
The spanner may be made for just one particular
Included in this group of tools are diagonal size notched nut , or it may have a hinged arm to
cutting pliers, files, hacksaws , twist drills, count adjust it to a range of sizes.
ersinks, chisels, and the various types of snips Pin spanners have a pin in place of a hook ,
used by the AMS to trim or cut material by and the pin fits into a hole in the outer part of
hand. (See fig. 5-7 . ) the nut . Face pin spanners are designed so that
Adequate coverage on the selection , care , and the pins fit into holes in the face of the nut .
use of cutting tools is contained in Tools and The AMS uses several different types of
Their Uses, NavPers 10085 ( Series ), and Airman, spanner wrenches which are manufactured for a
NavPers 10307 (Series), and is therefore not specific job . Figure 5-11 shows a special spanner
repeated here . being used on a wheel nut of a main landing
wheel .
MISCELLANEOUS TOOLS
TENSIOMETER
Miscellaneous tools are tools that do not fall
into the category of striking or cutting tools. The tensiometer is an instrument used in
Some of the miscellaneous tools that are of checking cable tension. The amount of tension
concern to the AMS are the flashlight, mechani applied in a cable linkage system is controlled by
cal fingers, inspection mirrors, and steel scales. turnbuckles in the system . NOTE : Tension is
(See fig. 5-8 . ) the amount of pulling force applied to the cable.
The Rate Training Manuals, Tools and Their A tensiometer is a useful instrument , but is
Uses, NavPers 10085 (Series), and Airman, not precision -built. It is inaccurate for cable
NavPers 10307 (Series ), adequately cover the tension under 30 pounds. All tensiometers in use
use and care of these tools and is therefore not must be checked for accuracy at least once a
repeated here . month .
One type of tensiometer is shown in figure
5-12 . This instrument works on the principle of
measuring the amount of force required to
SPECIAL TOOLS deflect a cable a certain distance at right angles
to its axis. The cable to be tested is placed under
TORQUE WRENCHES the two blocks on the instrument, and the lever
assembly on the side of the instrument is pulled
There are times when , for engineering reasons, down. Movement of this lever pushes up on the
a definite pressure must be applied to a nut. In center block , called a riser. The riser pushes the
such cases a torque Wrench must be used. The cable at right angles to the two clamping points.
three most commonly used torque Wrenches are The force required to do this is indicated by a
the Deflecting Beam , Dial Indicating , and Micro
> > pointer on the dial . Different risers are used with
meter Setting types. ( See fig. 5-9 .) different size cables . Each riser carries an identi
Adequate coverage on the selection , care , and fying number and is easily inserted in the
use of torque wrenches is contained in Tools and instrument.
Their Uses, NavPers 10085 ( Series ), and Airman , Each tensiometer is supplied with a calibra
NavPers 10307 (Series ), and is therefore not tion table to convert the dial readings into
repeated here . pounds. One of these calibration tables is illu
strated in figure 5-12. For example, in using a
SPANNER WRENCHES No. 2 riser with a 3/16 inch-diameter cable , if
the pointer on the dial indicates 48 , the actual
Many special nuts are made with notches cut tension on the cable is 100 pounds. It will be
into their outer edge. For these nuts, a hook noted that in the case of this particular instru
spanner ( fig. 5-10) is required . This is a wrench ment, the No. 1 riser is used with 1 / 16-, 3/32-,
that has a curved area with a lug on the end . and 1 / 8-inch-diameter cables.
90
Chapter 5 - SHEET-METAL WORKING MACHINES , TOOLS , AND PROCEDURES
POINTS
STRAIGHT SNIPS
00
THROAT
DIAGONAL CUTTING PLIERS
AVIATION SNIPS
Snoorsoola
MMMM
WWWWWWWWWWWWWW
HACKSAWS
TYPICAL BIT TYPE COUNTERSINK

HEEL -FACE TIP
COLD CHISEL
LENGTH
-TANG
CAPE CHISEL
SINGLE - CUT
ROUND NOSE
COARSE BASTARD SECOND- CUT SMOOTH
DIAMOND POINT
DOUBLE - CUT
TYPES OF POINTS ON METAL
FILE NOMENCLATURE AND GRADES OF FILE TEFTH CUTTING CHISELS
AM.1123
Figure 5-7 . - Types of cutting tools .
91
MECHANICAL FINGERS
wan
UOT TUDU
Voor
RU
9.
RIGID TYPE
8 THS .
IT 2
‫سلسبيليا‬
17 16 THS.
32 NDS .
21
N
EXTENDED POSITION RETRACTED POSITION
(A) (B) 64 THS.
STEEL SCALE
32
INSPECTION MIRROR
www
AM.1126
Figure 5-8 . -Miscellaneous tools.
92
90 DEGREES
M
I
T
DIAL
INDICATING W
i
n
c
o
n
f
o
n
d
i
b
i
l
e
v
i
n
o
MICROMETER
SETTING
DEFLECTING BEAM
AM.30
Figure 5-9 . - Torque Wrenches.
CAUTION : The calibration table applies to top of the instrument is moved to the closed
the particular instrument only and cannot be position which locks the pointer in place . Then ,
used with any other . For this reason , the the lever assembly is released and the instrument
calibration table is secured inside the cover of removed from the cable with the pointer locked
the box in which the instrument is kept. The in position . After the reading has been taken,
chart is serialized with the same serial number as the brake lever rod is moved to the open
the instrument . position , and the pointer will return to zero .
During the adjustment of turnbuckles , the The tensiometer, like any other measuring
calibration table must be used to obtain the instrument , is a delicate piece of equipment and
desired tension in a cable . For example , if it is should be handled carefully. Tensiometers
desired to obtain a tension of 110 pounds in a should never be stored in a toolbox .
3 / 16 - inch -diameter cable, the No. 2 riser is Temperature changes must be considered in
inserted in the instrument and the figure oppo cable type systems since this will affect cable
site 110 pounds is read from the calibration tensions. When a temperature is encountered
table . In this case , the figure is 52. The that is lower than that at which the aircraft was
turnbuckle is then adjusted until the pointer rigged , the cables become slack because the
>
indicates 52 on the dial . (NOTE : Tensiometer aircraft structure contracts more than the cables .
readings should not be taken within 6 inches of When temperatures higher than that at which
any turnbuckle , end fitting, or quick discon the aircraft was rigged are encountered, the
nect.) aircraft structure expands more than the cables
In some cases, the position of the tensiometer and the cable tension is increased.
on the cable may be such that the face of the The cables in any cable linkage system are
dial cannot be seen by the operator. In such rigged in accordance with a temperature chart
cases, after the lever has been set and the pointer which is contained in the applicable Mainte
moved on the dial, the brake lever rod on the nance Instructions Manual. This chart will give
93
the proper tensions for the various temperature on the model shown in figure 5-13 . On some
changes above and below the temperature at models the depth of cut adjustment can be made
which the system was rigged . in increments of 0.0008 inch. The operator can
change cutters and adjust their depth without
RIVET HEAD SHAVER the use of special tools. Once the depth is set,
the positive action of the serrated adjustment
The rivet head shaver shown in figure 5-13 is locking collar prevents accidental loss of setting.
used by the AMS to smooth countersunk rivet The AMS should position the cutters directly
heads that protrude slightly but are still within over the rivet head , holding the tool at an angle
specified limits. The rivet head shaver is also of 90 degrees to the surface being smoothed .
called a Micro Miller. The depth of cut adjust With the tool turning maximum rpm , it is then
ment can be made in increments of 0.0005 inch pressed in towards the surface , maintaining the
90-degree angle. The pressure feet will then be
compressed until they bottom out . At this time ,
assuming the rivet head shaver is adjusted
correctly prior to the shaving operation , the
rivet head will be shaved aerodynamically
smooth .
HOOK
SPANNER WRENCH
ADJUSTABLE HOOK
SPANNER WRENCH
SPANNER
WRENCH
od PIN
SPANNER WRENCH
AM.304
Figure 5-11 . -Using a special spanner wrench on a
wheel nut of a main landing wheel.
PNEUMATIC RIVETERS
FACE PIN Rivet guns vary in size and shape and have a
SPANNER WRENCH
variety of handles and grips, ranging from the
offset type to the pistol grip type . Nearly all
riveting is done with pneumatic riveters . The
AM.31 pneumatic riveting guns operate on compressed
Figure 5-10 . - General- purpose spanner wrenches. air supplied from a compressor or storage tank .
94
LEFT SECTOR RIGHT
NO . 2 RISER
BRAKE LEVER ROD
CABLE TENSION 100

INDICATOR
10 90 - 3/16 "
DIAMETER CABLE
80
30
50
· LEVER ASSEMBLY
No. 1 Riser NO . 2 No. 3

DIA 1/16 3/32 1/8 Tension 5/32 3/ 16 7/32 1/4
Lbs .
14 15 21 30 14 20
18 22 27 40 18 25
23 27 33 50 22 29
27 32 39 60 26 33
31 37 44 70 29 37
35 41 49 80 32 41
39 45 54 90 35 45
43 49 59 100 38 48
46 53 63 110 41 52
49 57 67 120 44 55
53 61 71 130 47 58
56 65 75 140 49 61
59 68 79 150 51 64
62 71 82 160 54 67
65 74 86 170 56 70
68 77 90 180 58 72
70 80 93 190 60 74
72 83 96 200 62 76
220 66 81
Typed figures are instru 240 70 85
ment scale reading cor 260 74 89
responding to tension 280 78 93
Instrument No. 6659
300 80 97
Model 401-10-2
AM.33
Figure 5-12. -Cable tensiometer and chart.
Normally, rivet guns are equipped with an air trigger, and into the cylinder in which the piston
regulator on the handle to control the amount moves. Air pressure forces the piston down
of air entering the gun . Regulated air entering against the rivet set and exhausts itself through
the gun (Fig . 5-14) passes through the handle side ports . The rivet set recoils, forcing the
and throttle valve, which is controlled by the piston back , and the cycle is repeated . Each time
95
Slow -Hitting Gun
ADJUSTMENT LOCKING SLEEVE

The slow -hitting gun has a speed of 2,500
bpm (blows per minute ). As long as the trigger is
TWT ..
held down , the rivet set continues to strike the
SKIRT
rivet. This gun is widely used for driving
medium - sized rivets. It is easier to control than
the one-shot gun.
CUTTER Fast-Hitting Gun
The fast -hitting gun heads the rivet with a

ADJUSTMENT
number of relatively lightweight blows . It strikes
LOCKING COLLAR between 2,500 and 5,000 bpm and is generally
used with the softer rivets. Like the slow -hitting
STABILIZER ASSEMBLY gun, it continues to strike the rivet head as long
as the trigger is depressed. This gun is sometimes
PRESSURE FOOT referred to as a vibrator.
Corner Riveter
The corner riveter is so named because it can

AM.305 be used in corners and in close quarters where
Figure 5-13. - Rivet head shaver. space is restricted . The main difference between
this riveter and the other types described lies in
the fact that in this type the set is very short and
the piston strikes the rivet set , the force is can be used in confined spaces as can be seen in
transmitted to the rivet. Rivet sets come in figure 5-15 .
various sizes and shapes to fit the various shaped
rivet heads. Squeeze Riveter
Several types of pneumatic riveters are in
general use . Included are the one-shot gun , The squeeze riveter differs from the other
slow -hitting gun , fast-hitting gun, corner riveter, riveters in that it forms the rivet head by means
and the squeeze riveter. (See fig. 5-15 .) The type of squeezing or compressing instead of by
of gun used depends on the particular job at distinct blows. Once it is adjusted for a particular
hand, each type having its advantages for certain type of work , it will form rivet heads of greater
types of work. Small parts can be riveted by one uniformity than the riveting guns. It is made
man if the part is accessible for both bucking both as a portable unit and as a stationary
and driving, provided the work is properly riveting machine. As a portable unit , it is larger
secured . The greater part of riveted work , than the riveting guns and can be used only for
however , requires two men . certain types of work that can be accommo
dated between the jaws. The stationary , or fixed
>
One - Shot Gun jaw , contains the set and is placed against the
rivet head in driving. The rivet squeezer illu
The one -shot gun is designed to drive the rivet strated in figure 5-15 is the pneumatic type.
with just one blow . It is larger and heavier than
other types and is generally used for heavy Rivet Gun Selection
riveting. Each time the trigger is depressed the
gun strikes one blow . It is rather difficult to The size and the type of gun used for a
control on light- gage metals . Under suitable particular job depend upon the size of rivets
conditions it is the fastest method of riveting. being driven and the accessibility of the rivet.
96
SLIDING VALVE PISTON SET SLEEVE BLANK RIVET SET
...
.
‫بهة‬
SET RETAINER
EXHAUST DEFLECTOR CYLINDER
THROTTLE
THROTTLE LEVER MOVEMENT OF AIR DURING

FORWARD STROKE
THROTTLE VALVE MOVEMENT OF AIR DURING
-THROTTLE TUBE REARWARD STROKE
M.
Sillas
BUSHING
AMAL REGULATOR
mo ADJUSTMENT
SCREW
AIR PATH
AM.306
Figure 5-14 . - Rivet gun internal airflow .
For driving medium -sized , heat -treated rivets Table 5-1 . - Approximate air pressures for rivet guns.
which are in accessible places, the slow -hitting
gun is preferred. For small, soft alloy rivets, the
fast-hitting gun is preferable. There will be
places where a conventional type gun cannot be Rivet size Air pressure psi
used . For this type of work, a corner gun is
3/32 35
employed.
The larger the rivet, the greater the air 1/8 40
5/32 60
pressure that is required. Air pressure reaches 3/16 90
the gun through a long, flexible hose. Approxi
mate air pressures for four of the most common
rivet sizes are given in table 5-1 . Conditions may
vary slightly with different alloys.
97
TAPS AND DIES
Taps and dies are used to cut threads in metal ,

ONE SHOT plastic , or hard rubber. The taps are used for
cutting internal threads, and the dies are used to
cut external threads. Taps and dies usually come
in complete sets, containing tap wrenches, die
stocks , guides , and the necessary screw - drivers
and wrenches to loosen and tighten adjusting
PISTOL GRIP screws and bolts .
Taps and dies should be kept clean and well
oiled when not in use. Store them so that they
SLOW HITTING do not contact each other or other tools . Tools
and Their Uses, NavPers 10085 ( Series ), de
scribes and illustrates the principles involved in
OFFSET the selection of the proper taps and/or dies for
HANDLE different types of work.
SCREW AND BOLT EXTRACTORS
Screw and bolt extractors are used to remove

broken screws and bolts without damaging the
COMPRESSION ( SQUEEZE ) RIVETER surrounding materials or the threaded hole .
The straight flute type extractors are available
in sizes to remove broken or damaged screws
having 1/4 to 1/2 inch outside diameter.
Spiral tapered extractors are sized to remove
screws and bolts from 3/16 inch to 2 1/8 inches
outside diameter .
Most sets of extractors include twist drills and
CORNER a drill guide . Tools and Their Uses, NavPers
10085 ( Series) , illustrates and outlines the pro
cedures to use in removing screws and bolts that
pe have been damaged or broken .

STRAP WRENCH
The strap wrench is used during assembly and

disassembly of cylinder type components. The
FAST HITTING strap wrench (fig. 5-16) has a metal body with a
webbed strap attached . To use this wrench , the
webbed strap is placed around the cylinder and
passed through the slot in the metal body . As
STRAIGHT the mechanic turns the wrench in the desired
direction , the webbed strap tightens around the
cylinder. This gripping action of the strap causes
the cylinder to turn. With the end cap held
stationary, the cylinder will be tightened or
loosened , depending upon the direction the
mechanic turns the wrench . The main advantage
AM.307 of this type of wrench, if used properly, is that
Figure 5.15.- Various types of rivet guns. it will not mar or damage the cylinder.
98
Chapter 5 - SHEET-METAL WORKING MACHINES , TOOLS, AND PROCEDURES
RIG PINS
Rig pins are used by the AMS in rigging

control systems . Figure 5-17 shows a rigging pin
kit used on one of the Navy's aircraft. As can be
seen by this kit, rig pins may come in various
sizes and shapes and may be designed for one or
many installations. The AMS should refer to the
specific Maintenance Instructions Manual for use
and selection of rig pins. Rigging of controls and
use of rig pins are discussed in chapter 8 of this
manual .
THROW BOARDS
Throw boards are special equipment used on

AM.308 specific aircraft for accurate measurement of
Figure 5-16. -Strap wrench . control surface travel . ( See fig. 5-18 . ) Each
REMOVE BEFORE FLIGHT

Hot
f
149173 380
338 310W38
L
доские! EQUIP
Liis
11pici
BURBANK,CCAL
PDS
GT
laim
AM.309
Figure 5-17. -Rigging pin kit.
99
RUDDER
W TAB
RUDDER
TT
O
TT
TT
PROTRACTOR
TT
TT
TT
NAMEPLATE
INSPECTION PLATE
TAIL
BOLTS
AM.310
Figure 5-18 . - Typical throw board used for rigging rudder and rudder tab controls.
throw board has a protractor type scale which out on the metal , the next step is to cut it out.
indicates a range of travel in degrees. Zero The type of cutting equipment to be used
degree normally indicates the neutral position of depends primarily upon the type and thickness
the control surface . When the throw board is of the material. Another consideration is the size
mounted in place and the control column/stick and number of pieces to be cut . A few fairly
is in neutral, the trailing edge of the control thin pieces of comparatively soft metal may be
surface should be aligned on zero . As the control more readily turned out by hand -trimming
column/stick is moved to its extreme limits , the methods. But for harder, metals, faster output,
AMS reads the corresponding degree indication and generally more workmanship results,
on the throw board . If the travel of the control machines designed for metal cutting purposes
surface is out of limits , the AMS should adjust are used .
cables , push-pull rods, control limit stops, etc. ,
as necessary , to obtain the correct control
surface travel . When inspecting and rigging con
trol surfaces, the specific Maintenance Instruc CUTTING EQUIPMENT
tions Manual should be consulted . The use of
Machines used in cutting sheet metal may be
throw boards is discussed further in chapter 8 .
divided into two groups -manually operated and
power operated. Each type of cutting machine
CUTTING SHEET METAL has a definite cutting capacity which should
never be exceeded . A few of the more common
Cutting of sheet metal is a common occur types that are available to the AMS are described
rence for the AMS. Once a project has been laid in this section .
100
Chapter 5 - SHEET -METAL WORKING MACHINES , TOOLS , AND PROCEDURES
Squaring Shears on the bed - the beginning and ending marks o

the cutting edge of the bed , and the cut made
Squaring shears ( fig. 5-19) are used for cutting A holddown mechanism positioned by hold
and squaring sheet metal . They may be foot down handles ( fig. 5-19 ) is incorporated in fron
operated or power operated. Squaring shears of the movable cutting edge in the crosshead . It
consist of a stationary blade attached to a bed , purpose is to clamp the work firmly in plac
and a movable blade attached to a crosshead . To while the cut is being made . The clamp
make a cut , the work is placed in the desired quickly and easily made -the operator merel
position on the bed of the machine and the rotates the handle toward himself and th
blade is moved through its downward stroke . holddown lowers into place. A firm downwar
The stroke of the cutter blade is always identical pressure on the handle at this time should rotat
in its relation to the bed . Foot-powered squaring the mechanism over center on its eccentric car
shears are equipped with a spring which raises and lock the holddown in place . Reverse th
the blade when foot pressure is taken off the action to release the work.
treadle . A scale graduated in fractions of an inch Three distinctly different operations-cuttin
is scribed on the bed. Two side guides, consisting to a line, squaring, and multiple cutting to
of thick steel bars , are fixed to the bed , one on specific size -may be accomplished on the squai
the left and one on the right. Each is placed so ing shears. When cutting to a line , proceed a
that its inboard edge creates a right angle with above - place the beginning and ending marks o
the cutting edge of the bed. These bars are used the cutting edge and make the cut . Squarin
to align the metal when absolutely square requires a sequence of several steps. First , squar
corners are desired. When cuts other than right one end of the sheet with one side. Then squar
angles are to be made across the width of a piece the remaining edges, holding one squared endo
of metal , the beginning and ending points of the the sheet against the side guide and making th
cut must be determined and marked in advance. cut , one edge at a time, until all edges have bee
>
Then the work is carefully placed into position squared .

When several pieces are to be cut to the sam
dimensions , make use of the adjustable gage sto
with which most squaring shears are equipped
HOLD -DOWN
-HANDLES SAFETY GUARD This stop is located behind the bed cutting edge
BACK GAGE CROSSHEAD and its purpose is to limit the amount of meta
BEVEL GAGE
SIDE GAGE that can be slipped between the cutting edges o
AITAS the blade and bed . The supporting rods for th
MIHANOMAN
stop gage are graduated in inches and fraction
of an inch , and the gage bar is rigged so that i
may be set and fixed at any point on the rods
BED
FRONT
GAGE
With the gage set at the desired distance fror
EXTENSION
CUTTING
BLADE
ARM the cutting blade , push each piece to be cu
against the stop . It is then possible to cut a
pieces to the same dimensions without measu
‫דייזי‬
FOOT TREADLE
ing and marking each one separately . (NOTE
Physically measure the first piece in such a serie
HOUSING to make sure that the stop is accurately set.)
12
"
Throatless Shears
13
GRADUATIONS ON BED ( ENLARGED)

Throatless shears (fig. 5-20) are constructe
so that sheets of any length may be cut and th
metal turned in any direction during the cuttin
AM.261 operation. Thus, irregular lines can be followed
Figure 5-19. - Squaring shears. or notches made without distorting the meta
101
This type of throatless shears is essentially an Unishear

adaptation of heavy handshears or snips in which
the handles are removed , one blade secured to a Unishear is a trade name for a type of
base , and a long lever attached to the tip of the portable power shears, used for cutting curves
movable blade . The heavy duty throatless shears and notches as well as straight-line cutting.
are capable of cutting stainless steel up to 0.083 This tool might be called a power -operated,
inch in thickness . combination snips . It has two short blades. The
lower blade is held in a fixed position. The
Hand Bench Shears upper blade moves up and down in short strokes
at a high rate of speed . Its chewing motion is the
The hand bench shears are similar in opera basis for the widely used nickname of this power
>
tion to a papercutter. They have one fixed blade tool - nibblers.” The tool will cut metal up to
and a movable blade , hinged at the back , similar its rated capacity which should never be ex
to the throatless shears except that the blades ceeded . Figure 5-21 illustrates an 18 - gage uni
are straight and , therefore , used only for straight
. shear .
cutting. Some bench shears have a punching The cutting blades are easily removed for
attachment on the end of the frame opposite the sharpening and replacement . The machine will
shearing blades . This attachment is for punching cut as fast as it can be fed up to 15 feet per
holes in metal sheets . minute . This is a ruggedly constructed machine;
and for satisfactory performance, the best of
care is necessary . It should be kept cleaned and
oiled at all times .
LEVER Hand-Operated Turret Punch

A hand-operated turret punch is shown in
STOP
figure 5-22. Twelve mated punches and dies are
mounted in a rotating turret . Each die block has
-KNIFE the size of hole it will punch, as well as the
thickness of the material it will accommodate ,
stamped on the front. These capacities are for
PLATE
mild steel, and this must be kept in mind when
punching stainless steel or other alloys.
The operation of the turret punch is simple :
release the locking handle on the side of the
punch frame, rotate the turret until the desired
punch set is lined up with the actuating mechan
ism (ram), then lock the turret into position .
Punch the hole by pulling the operating lever
toward the operator , which actuates the ram and
AM, 262
punch.
Figure 5-20. -Throatless shears.
MACHINE FORMING OF SHEET METAL

For cutting stock that is narrower in width
than the length of the blades, the lever of the SLIP -ROLL FORMING MACHINE
shears can be pulled all the way down . When
cutting larger pieces, a continuous series of short Sheet metal can be formed into curved shapes
bites should be made , since complete closing of over a pipe or a mandrel, but the slip -roll
the blade tends to tear the sheet at the end of forming machine ( fig. 5-23 ) is much easier to use
each cut . and produces more accurate bends . Rolling
102
Willich
V
SLA
YMI ?
U
A
d
a
g
o
d
LEY
TOR
o
ntn
sta
kon
tri pulseira
*
*
*
nis
* mi
WHISPER 549
6 TMC3LAXE, ELECAM
CN
TOV .
.
0
...
AM.263
Figure 5-21 . -18-gage unishear.
machines are available in various sizes and
capacities ; some are hand operated , like the one
shown in figure 5-23 , and others are power
operated .
MACHINE
DEMAN
NA
The machine shown in the illustration has two
WIE MADE
PHILA..
rollers in the front and one roller at the rear.

Co.
N
Adjusting screws on each end of the machine

U.S.A
sein control the distance between the front rolls. By

IM
varying the adjustments, the machine can be

used to form cylinders, cones, and other curved
shapes. The front rolls grip the metal and pull it
34
into the machine; therefore, the adjustment of
TURK PICK
TCA
distance between the two front rolls is made on
PA.
the basis of the thickness of the sheet being

worked .
To form a cylinder in the machine ( fig. 5-24),
follow this procedure :
1. Adjust the front rolls so that they will grip
the sheet properly .
2. Adjust the rear roll to height that is less
AM.264 than enough to form the desired radius of the
Figure 5-22. - Hand-operated turret punch . cylinder.
103
HOUSING -GROOVES OPERATING HANDLE
LOWER FRONT UPPER FRONT

ROLL ROLL
D.0000
KNURLED ADJUSTING SCREWS -BASE GROOVES

KNURLED
ADJUSTING SCREWS -
AM.265
Figure 5-23 . - Slip -roll forming machine.
-
th
SECTIONAL VIEW
OF ROLLS
RS
AM.266
Figure 5-24.- Forming a cylinder.
104
3. Check to be sure that all three rolls are rolls in such a manner that the element lines
parallel. (Same space exists between any two (A-A’ , B-B ’ , etc. , in the illustration) pass over
>
rollers at each end of the rollers.) the rear roll in a line parallel to the roll. This
4. Start the sheet into the space between the involves slipping the large end of the cone
two front rolls . As soon as the front rolls have through the rolls at a slightly faster rate than the
gripped the sheet , raise the free end of the sheet small end is being rolled through .
slightly . The grooves at the end of the rolls can be
5. Pass the entire sheet through the rolls . This used to form circles of wire or rod ; they can also
forms part of the curve required for the cylin be used to roll wired edges , as shown in figure
der . 5-26 .
6. Set the rear roll higher to form a shorter
radius .
7. Turn the partially formed sheet end over
end and again pass it through the rolls.
8. Continue turning the sheet end over end
and passing it through the rolls , each time
adjusting the rear roll for a new radius, un til a
truly cylindrical shape has been formed .
9. Remove the cylinder from the machine.
The top front roll has a quick -releasing device by
which one can release one end of the roll. This
allows the released end of the roll to be raised and
the newly formed cylinder slipped off just as
one would slip a ring from his finger.
Conical shapes can be formed by setting the
back roll at an angle before running the sheet
through it , or they can be made with the rolls
parallel. (See fig . 5-25 .) To make a cone with the
rolls parallel, the sheet must be fed through the
7
Figure 5-26. -Rolling a wired edge.
AM. 268
ROTARY MACHINE
The rotary machine shown in figure 5-27 is

used on cylindrical and flat sheet metal to shape
.
the edge or to form a bead along the edge .

1
Various shaped rolls (some illustrated in fig.

8
5-28) can be installed on the rotary machine to

B
perform the following operations; beading, turn
ing, wiring, crimping, and burring. These opera
tions are described in the following paragraphs.
-
C c'
Beading Rolls
Beading rolls are used for turning beads
( grooves) on such items as tubing, cans, and
buckets ; and for stiffening and gripping. Beads
may also be placed on sheet stock that is to be
welded. There are several different types of
AM. 267 beading rolls. Those shown in figure 5-28 are the
Figure 5-25 . - Rolling a conical shape. single bead rolls. Whenever beading , the groove
105
should not be made too deeply in a single Wiring Rolls

rotation as this tends to weaken the metal .
Wiring rolls are used to finish the wired edges
prepared in the turning rolls. To use the wiring
rolls, adjust the top roll so that it is directly
CRANKSCREW
above the point on the lower roll where the
beveled and flat surfaces meet , as shown in (A)
-UPPER ROLL of figure 5-29 . Adjust the guide to the position
LOCK NUT shown in ( B) , then bring the top roll down so
that it will turn the edge of the metal as shown
ADJUSTING SCREW TOWER ROLL
in (C ) . Remove the stock from the machine by
OPERATION HANDLE raising the top roll .
Crimping Rolls
Crimping rolls are used to make one end of a
pipe smaller than the other so that two sections
AM.269 may be slipped together, one end into the other.
>
Figure 5-27 . - Rotary machine. A bead is placed on a pipe first, then it is

crimped. The bead forms a shoulder to keep the
Turning Rolls pipe from slipping too far into the adjoining
section.
Turning rolls are used for turning an edge to
receive a stiffening wire. When turning an edge , Burring Rolls
rest the cylinder to be wired on the lower wheel
and press against the gage . The gage is adjusted Burring is perhaps the most difficult opera
according to the size of wire to be used . With tion performed on a rotary machine . Before
the work set in place , bring down the upper roll placing the work in the machine , make sure that
until it grips the metal . Turn the crank slowly , the cylinder or circular disc to be burred is cut
holding the metal so that it will feed into the or formed as perfectly round as possible . Then
rolls while continuing to press against the guide. adjust the gage on the machine so that the space
After the first revolution , gradually raise the between the inside of the upper roll and the gage
metal until it touches the outer face of the top is set to the width of the burr. Next , place the
roll . Remove the stock by raising the top roll. object between the rolls and against the gage ,
H
1
SINGLE BURRING ROLLS STRAIGHT TURNING ROLLS WIRING ROLLS
BEAD ROLLS CRIMPING ROLLS
AM.270
Figure 5-28. -Roll dies used on rotary machine.
106
Chapter 5 - SHEET -METAL WORKING MACHINES, TOOLS, AND PROCEDURES
and lower the upper roll until it scores the They must not be used as backing when chisel
material slightly. Now turn the crank slowly , ing holes or notches in sheet metal , or when
allowing the metal to slide between the thumb performing any other job which might damage
and fingers. Apply a slight upward pressure as the faces of the stakes.
the metal passes between the rolls . After the
first revolution , lower the top roll and again pass BENDING IN A VISE
the metal between the rolls. Repeat this process,
raising the edge slightly with each complete Straight-line bends of comparatively short
revolution of the material until the edge has sections can be made by hand with the aid of
been burred to the proper angle. wooden or metal bending blocks . After the part
has been laid out and cut to size , clamp it rigidly
along the bend line between two forming blocks
held in a vise . The forming blocks usually have
GUIDE one edge rounded to give the desired bend
UPPER radius . ( See fig. 5-31 . ) By tapping lightly with a
ROLL
rubber, plastic , or rawhide mallet , bend the
metal protruding beyond the bending block to
the desired angle.
LOWER Start tapping at one end , and work back and
ROLL forth along the edge , making the bend gradually
( A) (B) (C) and evenly. Continue this process until the
protruding metal is bent to the desired angle. If
a large amount of metal extends beyond the
AM.271
bending blocks , maintain enough hand pressure
against the protruding sheet to prevent the metal
Figure 5.29. -Wiring operation. from bouncing. Remove any irregularity in the
flange by holding a straight block of hardwood
edgewise against the bend and striking it with
BENDING SHEET METAL heavy blows of a hammer or mallet . If the
amount of metal protruding beyond the bending
Straight-line bends and folds in sheet metal blocks is small , make the entire bend by using
are ordinarily made on the cornice brake and bar the hardwood block and hammer.
folder; however , a considerable amount of bend
>
Curved flanged parts have mold lines that are
ing is also carried out by hand -forming methods. either concave or convex . The concave flange is
Hand forming may be accomplished by using formed by stretching , while the convex flange is
stakes , blocks of wood , angle iron , a vise , or the
> formed by shrinking. Such parts are shaped with
edge of a bench. the aid of hardwood or metal form blocks.
These blocks are made in pairs and specifically
BENDING OVER STAKES for the shape of the part being formed . Each
pair fits exactly and conforms to the actual
Stakes are used to back up sheet metal for the dimension and contour of the finished article .
forming of many different curves, angles, and Cut the material to be formed to size ,
seams in sheet metal . Stakes are available in a allowing about one-quarter inch of excess ma
wide variety of shapes, some of which are shown terial for trim . File and smooth the edges of the
in figure 5-30. The stakes are held securely in a material to remove all nicks caused by the
stake holder or stake plate (also illustrated ) cutting tools. This reduces the possibility of the
which is anchored in a workbench . The stake material cracking at the edges during the form
holder contains a variety of holes to fit a ing operation . Place the material between the
number of different types of shanks. form blocks and clamp tightly in a vise so that
Although stakes are by no means delicate, the material will not move or shift. Clamp the
they must be handled with reasonable care. work as closely as possible to the particular area
107
BEAKHORN STAKE
CREASINGSTAKE
WITH HORN
COPPERSMITH
Toon SQUARE
STAKE 7 APRON
BLOWHORN STAKE
SHANK
COMMON
SQUARE STAKE U HATCHET BEVEL EDGE
STAKE BOTTOM STAKE SQUARE STAKE
T
CANDLE MOLD STAKE
HORN
CONDUCTOR STAKE
T
NEEDLECASE STAKE
SOLID
MANDREL STAKE
1
HOLLOW MANDREL
STAKE DOUBLE -SEAMING STAKE
AM.272
Figure 5-30 . - Stakes and stake plate.
being formed to prevent strain on the form extreme ends of the part , and continue toward
block and to keep the material from slipping . the center of the bend. This procedure permits
Concave surfaces are formed by stretching the some of the material at the ends of the part to
material over a form block . (See fig . 5-32. ) Using be worked into the center of the curve where it
a plastic or rawhide mallet with a smooth, will be needed . Continue hammering until the
slightly rounded face, start hammering at the metal is gradually worked down over the entire
108
flange and flush with the form block. After the BENDING ON A BRAKE
flange is formed, trim off the excess material
and check the part for accuracy . The easiest and most accurate method of
making straight-line bends on a piece of sheet
metal is by the use of a box and pan brake or a
cornice brake. The use of these brakes is
MATERIAL TO BE FORMED
relatively simple; however, if they are not used
FORM BLOCKS correctly , the time and the work involved in
7 ( TYP) BEVEL TO ALLOW FOR
MATERIAL SPRING BACK computing and laying out of bend allowance, as
well as the metal , are wasted . Before bending
any work demanding an accurate bend radius
and definite leg length, the settings of the brake
should be checked with a piece of scrap metal .
When making an ordinary bend on a brake , place
the sheet to be bent on the bed so that the bend
line is directly under the upper jaw or clamping
bar, then pull down the clamping bar handle.
>
This brings the clamping bar down to hold the

AM.273 sheet firmly in place . Set the stop for the proper
Figure 5-31 . -Preparation for straight bend by hand. angle or amount of bend , and make the bend by
raising the bending leaf until it strikes the stop.
If more than one bend is to be made , bring the
next bend line under the clamping bar and
Convex surfaces are formed by shrinking the repeat the bending procedure.
material over a form block . (See fig. 5-33 . ) Using
a wooden or plastic shrinking mallet and a Cornice Brake
backup or wedge block , start at the center of the
curve and work toward both ends. Hammer the
The cornice brake ( fig. 5-34 ) is designed for
flange down over the form , striking the metal bending large sheets of metal . It is adjustable for
with glancing blows at an angle of approxi
mately 45 degrees, and with a motion that will
tend to pull the part away from the radius of the
form block . While working the metal down over SMOOTH , SLIGHTLY ROUNDED
the form block , the wedge block is used to keep PLASTIC OR RAWHIDE MALLET
the edge of the flange as nearly perpendicular to
the form block as possible . The wedge block also
lessens the possibility of buckles and of splitting
or cracking the metal . MATERIAL
BEING
Another method of hand forming convex FORMED
flanges is by using a lead bar or strap. The
material , while secured in the form block , is
struck by the lead strap which takes the shape of FORM
BLOCKS
the part being formed and forces it down against
the form block . One advantage in using this
method is that the metal is formed without
marring or wrinkling and is not thinned out as
much as it would be by other methods of hand
forming. This method is also illustrated in figure
5-33 . After the flange is formed by either
method , trim off the excess material and check AM.274
the part for accuracy . Figure 5-32. - Forming concave hand bend.
109
BACKUP BLOCK
SHRINKING UNFORMED MATERIAL
MALLET
SHRINKING
MALLET
THE
BACKUP
MATERIAL
BEING
FORMED
BLOCK
V FORM
BLOCKS
FORM BLOCKS
LEAD BAR
‫ک مرری‬
FORM
BLOCK
MATERIAL BEING
FOR MED
AM.275
Figure 5-33.-Forming convex hand bends.
clamping a wide variety of metal thicknesses and limited. This is a useful feature when it is desired
for bending this metal to a variety of radii. to make a number of pieces with the same angle
The brake is equipped with a stop gage , of bend .
consisting of a rod, a yoke , and a setscrew , by The standard cornice brake is extremely
means of which the travel of the bending leaf is useful for making single hems , double hems,
110
Chapter 5 - SHEET -METAL WORKING MACHINES, TOOLS , AND PROCEDURES
lock seams, and various other shapes , some of The finger brake is particularly useful in the
which require the use of molds. The molds are forming of boxes, pans, and other similar shapes.
fastened to the bending leaf of the brake by If these shapes were formed on a cornice brake,
means of friction clamps, in such a position that one would have to straighten part of the bend
the work can be formed over them . Figure 5-35 on one side of the box in order to make the last
shows sheet that is ready to be formed over a bend . In the finger brake, simply remove the
mold attached to a cornice brake . fingers that in the way and use only the fingers
required to make the bend .
Box and Pan Brake The fingers are secured to the upper leaf by
thumbscrews, as shown in figure 5-37 . All
The box and pan brake ( fig. 5-36 ) is often fingers which are not removed for any operation
called the finger brake since it does not have one must be securely seated and firmly tightened
solid upper jaw as does the cornice brake , but before the brake is used .
instead is equipped with a series of steel fingers To keep brakes in good condition , keep the
of varying widths. The finger brake can be used working parts well oiled and be sure that the
to do everything that the cornice brake can do jaws are free of rust and dirt . In operating the
and several things that the cornice brake cannot brakes , take care to avoid doing anything that
do . would spring the parts, force them out of
CUMPING MR HANDLES COUNTER -WEIGHT

(TYPICAL TWO PLACES ) ( TYPICAL TWO PLACES)
-UPPER JAWOR CLAMPING MAR

DOOD
OOOO
ADJUSTABLE STOP
LENDING LEAP
BENDING LEAF HANDLE

(TYPICAL TWO PLACES )
UPPER JAW OR CUMPING MAR UPPER JAWOR CLAMPING MAR
REQUIRED BEND RADIUS FORMED MATERIAL
MATERIAL TO KE FORMED
BENDING LEAF
BENDING LEAF
X STATIONARY DED
BENDING OPERATION
Figure 5-34 . - Cornice brake and operation .

STATIONARY BED
AM.276
111
alignment, or otherwise damage them . Never use

brakes for bending metal that is beyond their
capacity as to thickness, shape, or type. Never
try to bend rod , wire, strap iron , or spring steel
sheets in a brake. If it is necessary to hammer
the work , take it out of the brake first.
UPPER JAW
STOCK
MOLD
Home
-LOWER JAW
AM.278
Figure 5-36 . - Box and pan brake being used to form box .
LEAF
AM.277
1
Figure 5-35. -Cornice brake with mold and stock.
BENDING ON BAR FOLDER AM.279

Figure 5-37 . - Finger secured in box and pan brake.
The bar folder may be used to bend and fold
metal in a number of different shapes, as
illustrated in figure 5-38 . This machine has two SHEET METAL EDGES AND SEAMS
adjustments, one for regulating the width of the
fold and the other to provide sharp or rounded REINFORCED EDGES
bends. To operate the bar folder, adjust the
thumbscrew to the specified width of the fold , There are several methods used to reinforce or
then turn the adjusting knob on the back of the stiffen the edges of sheet metal . One method is
machine for the desired sharpness of the bend. to form either a single or double hem ; another is
Insert the metal under the folding blade until it to reinforce the edge with a wire or rod .
rests against the stops. Hold the metal firmly in A single hem is formed by simply turning the
place with one hand , grasp the handle with the metal back on itself once , as shown in figure
>
other , and pull forward until the desired fold is

> 5-40. A double hem , also shown in the illustra
made . The necessary steps in making a single tion , is formed in the same manner, except that
hem are illustrated in figure 5-39. the metal is folded twice instead of once .
112
Chapter 5 - SHEET -METAL WORKING MACHINES, TOOLS, AND PROCEDURES
(A ) (B)
STARTING THE MAKING THE FOLD
FOLD
(C ) FLATTENING THE HEM
AM.281
Figure 5-39. -Bar folding a single hem.
V
SINGLE HEM DOUBLE HEM
AM.282
Figure 5-40. -Single and double hems.
SHEET METAL SEAMS
AM.280 The place where two sheets of metal are

Figure 5-38. - Types of bends made on a bar folder. joined together is called a seam . The three most
common types of seams used in sheet metal
work are the lap seam, grooved seam , and the
A wire edge is made by wrapping the metal standing seam .
around a piece of wire or rod , the metal being The lap seam is the least difficult to fabricate.
bent by hand or on a bar folder. An allowance In making this seam , the pieces of stock are
equal to two and one-half times the diameter of merely lapped one over the other and secured by
the wire should be provided for the fold to riveting or soldering, or both, the method used
receive the wire . Figure 5-41 shows a wire edge depending upon the degree of structural strength
being formed by hand although a much more required and whether or not a watertight seam is
workmanlike job is accomplished by using the required .
rotary machine illustrated in figure 5-27. The A grooved seam is used in the construction of
final wrapping operation may be continued cylindrical objects, such as funnels, pipe sec
either with the peen of a hammer or with a tions, containers, marking buoys , and tanks. The
>
wiring machine . steps in forming a grooved seam are shown in

113
Us
tool
- 바 -a
2
3 DISTRIBUTION OF
SEAM ALLOWANCE
AM.285
Figure 5-43. - Steps in forming a standing seam .
section , the remaining portion on the other.

Sections A and B are equal , and C is one
thickness of the metal less than A.
BEND ALLOWANCE
AM.283
When bending metal to exact dimensions , the
Figure 5-41 . -Hand forming a wire edge. amount of material used in forming the bend
must be known . The amount of material which
figure 5-42 . Step (C) is accomplished with either is actually used in making the bend is known as
a hand or machine groover . BEND ALLOWANCE .
The standing seam is frequently used when Bending compresses the metal on the inside of
joining two sections or parts of an object, such the bend and stretches the metal on the outside
as the splash ring to the body of a funnel. The of the bend . Approximately halfway between
steps in making a standing seam are shown in these two extremes lies a space that neither
figure 5-43. If the object has straight sides, the shrinks nor stretches, but retains the same
flanges may be turned in the bar folder; and if length. This is known as the neutral line or
cylindrical, the flanges are turned on the burring neutral axis. Figure 5-44' illustrates the neutral
machine. Notice the distribution of the allow axis of a bend .. It is along this neutral axis that
ance for the seam. Two -thirds of it is on one bend allowance is computed .
(A) ( B)
BEND ALLOWANCE TERMS
>C Familiarity with the following terms is neces

sary for an understanding of bend allowance and
OPEN LOCKS LOCKS HOOKED
its application to an actual bending job. Figure
(c ) 5-45 illustrates most of these terms .
Leg. The longer part of aa formed angle.
Flange. The shorter part of a formed angle
SEAM GROOVED the opposite of leg. If each side of the angle is
the same length , then each is known as a leg.
Mold Line (ML) . The line formed by extend
ing the outside surfaces of the leg and flange.
AM.284 ( An imaginary point from which real base
Figure 5-42. - Forming a grooved seam. measurements are provided on drawings.)
114
Radius ( R) . The radius of the bend - always to

the inside of the metal being formed unless
otherwise stated .. ( The minimum allowable
radius for bending a given type and thickness of
material should always be ascertained before
proceeding with any bend allowance calcula
tions . )
Setback ( SB) . The setback is the distance
from the bend tangent line to the mold point. In
a 90 -degree bend SB = R + T (radius of the bend
plus thickness of the metal ). The setback dimen
SHRINKING sion must be determined prior to making the
bend as it (setback) is used in determining the
location of the beginning bend tangent line.
NEUTRAL
AXIS Bend Line ( also called BRAKE or SIGHT
line ). The layout line on the metal being formed
which is set even with the nose of the brake and
STRETCHING
serves as a guide in bending the work . ( Before
forming a bend , it must be decided which end of
AM.286
the material can be most conveniently inserted
in the brake . The bend line is then measured and
Figure 5.44 . - Neutral axis .
marked off with a soft-lead pencil from the bend
tangent line closest to the end which is to be
Bend Tangent Line ( BL) . The line at which placed under the brake . This measurement
the metal starts to bend and the line at which should be equal to the radius of the bend. The
the metal stops curving. All the space between metal is then inserted in the brake so that the
the bend tangent lines is the bend allowance . nose of the brake will fall directly over the bend
Bend Allowance ( BA ) . The amount of ma line , as shown in figure 5-46 .)
terial consumed in making a bend . Flat ( short for flat portion). The flat portion
or flat of a part is that portion not included in
the bend . It is equal to the base measurement
minus the setback .
BEND THICKNESS ( )
TANGENT LINE
( BL ) BEND
FLANGE LINE MANDREL
F
Ja
L
А LEG BEND
T
ALLOWANCE -JAW
RADIUS (R )
-BEND ALLOWANCE (BA) PIECE
MOLD LINE (ML) TO BE
FLAT
BENT
MOLD POINT R +t SETBACK (90° BEND)
BENDING BED
-BASE MEASUREMENT
LEAF
AM.287 ' AM.288

Figure 5-45. –Bend allowance terms. Figure 5-46 . - Locating bend line in brake.
115
Base Measurement. The base measurement is Table 5-3 shows the bend allowance per
the outside dimensions of a formed part . Base degree of bend for some commonly used thick
measurement will be given on the drawing or nesses , and bend radii used in aircraft construc
blueprint , or may be obtained from the original tion . This table is based on the foregoing
part . formula. The blank spaces on the table are
Closed Angle. An angle that is less than 90 spaces where values were omitted because the
degrees when measured between legs, or more bends would be too sharp for satisfactory
than 90 degrees when the amount of bend is production.
measured . (See fig. 5-47 .)
Open Angle. An angle that is more than 90
degrees when measured between legs , or less
than 90 degrees when the amount of bend is LAYOUT PRACTICES
measured.
K No. One of 179 numbers on the K chart
In laying out metal prior to bending it to a
corresponding to one of the angles between 0 desired shape, there are certain precautions
and 180 degrees to which metal can be bent . which should be observed . In the following
( See table 5-2 ). Whenever metal is to be bent to
paragraphs are some of the more important
any angle other than 90 degrees (K No. of 1.0), precautions; for information on the use of
the corresponding K No. is selected from the layout tools refer to Tools and Their Uses,
chart and is multiplied by the sum of the radius NavPers 10085-B.
and the thickness of the metal. The product is Every precaution must be taken to avoid
the amount of setback for the bend .
marring aluminum -alloy sheet and even steel
sheet should be carefully handled. To protect
the under surface of the material from any
possible damage , it is often advisable to place a
LOPE piece of heavy paper , felt, or plywood between
NANG
LE the material and the working surface . In working
135° with a large sheet of material, it is important to
45° CLOSED ANGU
avoid bending it ; hence , it is a good idea to have
a helper in placing it on the working surface.
A layout fluid should be applied to the
surface of the metal so that the pattern will
AM.289 stand out clearly . Any one of several approved
Figure 5-47. -Open and closed angles. fluids may be used . Zinc chromate and bluing
fluid are two of the most commonly used . Since
zinc chromate protects a metal surface against
BEND ALLOWANCE FORMULA corrosion and also serves as a base for paint, it
need not be removed after the layout is com
Ву experimentation with actual bends in pleted. Bluing fluid is merely a blue dye dis
metals , aircraft engineers have found that ac solved in alcohol . It does not protect metal
curate bending results could be obtained by against corrosion or serve as a paint binder, so it
using the following formula for any degree of should be removed either with ordinary paint
bend from 1 to 180 . thinner or alcohol.
To begin the layout , one edge of the metal
( 0.01743 x R +0.0078 x T) x N = BA should be straight. Use the squaring shears if
necessary , then test the job with a straightedge.
where All measurements can then be based on the
straight edge of the sheet. Lines at a known
R equals the desired bend radius , angle or parallel to the straight edge can be made
T equals thickness of the material, and by marking off points from a combination
N equals number of degrees of bend . square held firmly against the straight edge .
116
Table 5-2. -K chart.

o
Aº K No. Aº K No. Aº K No. Aº K No.
1 0.00873 46 0.42447 91 1.0176 136 2.4751

2 .01745 47 . 43481
. 92 1.0355 137 2.5386
3 .02618 48 . 44523 93 1.0538 138 2.6051
4 .03492 49 .45573 94 1.0724 139 2.6746
5 .04366 50 .46631 95 1.0913 140 2.7475
6 .05241
. 51 .47697 96 1.1106 141 2.8237
7 .06116
. 52 .48773 97 1.1303 142 2.9042
8 .06993 53 .49858 98 1.1504 143 2.9887
9 .07870 54 .50952 99 1.1708 144 3.0777
10 .08749 55 .52057 100 1.1917 145 3.1716
11 .09629
o 56 .53171
. 101 1. 2131 146 3.2708
12 .10510 57 .54295 102 1.2349 147 3.3759
13 . 11393 58 .55431 103 1.2572 148 3.4874
14 . 12278
.
59 .56577 104 1.2799 149 3.6059
15 . 13165 60 .57735 105 1.3023 150 3.7320
16 . 14054 61 .58904 106 1.3270 151 3.8667
17 .14945
.
62 .60086
. 107 1.3514 152 4.0108
18 . 15838 63 .61280 108 1.3764 153 4.1653
19 .16734 64 .62487 109 1.4019 154 4.3315
20 .17633 65 .63707 110 1.4281 155 4.5107
21 . 18534 66 .64941 111 1.4550 156 4.7046
22 . 19438 67 .66188
.
112 1.4826 157 4.9151
23 . 20345 68 .67451 113 1.5108 158 5.1445
24 .21256 69 .68728 114 1.5399 159 5.3995
25 .22169 70 .70021
. 115 1.5697 160 5.6713
26 . 23087 71 .71329 116 1.6003 161 5.9758
27 .24008 72 .72654 117 1.6318 162 6.3137
28 .24933 73 .73396 118 1.6643 163 6.6911
29 .25862 74 .75355 119 1.6977 164 7.1154
30 . 26795 75 .76733 120 1.7320 165 7.5957
31 . 27732 76 .78128
.
121 1.7675 166 8. 1443
32 . 28674 77 .79543 122 1.8040 187 8.7769
33 . 29621
0 78 .80978 123 1.8418 168 9.5144
34 .30573 79 .82434 124 1.8807 169 10.385
35 .31530 80 .83910
.
125 1.9210 170 11.430
36 .32492 81 .85408
. 126 1.9626 171 12.706
37 .33459
. 82 .869 29
. 127 2.0057 172 14.301
38 .34433 83 .88472 128 2.0503 173 16.350
39 .35412 84 .90040 129 2.0965 174 19.081
40 .36397 85 .91633 130 2.1445 175 22.904
41 .37388 86 .93251
.
131 2.1943 176 26.636
42 .38386 87 .94896 132 2.2460 177 38. 188
43 .39391 88 .96569
. 133 2. 2998 178 57.290
44 . 40403 89 .98270 134 2.3558 179 114.590
45 .41421 90 1.00000 135 2.4142 180 Infinite
117
Table 5-3. -Bend allowance per degree of bend .
THICKNESS
RADIUS 0.020 0.025 0.032 0.040 0.050 0.063
1/32 0.00070 0.00074 0.00079
1/16 .00125
.
.00129
0 .00135 0.00140 0.00148 0.00158
3/32 .00179 .00183 .00188 .00195 .00202 .00212
1/8 .00234 .00238 .00243 .00249 .00257 .00267
5/32 .00288 .00292 .00297 .00304 .00311 .00321
3/16 .00342 .00347 .00352 .00358 .00366 . 00376
7/32 .00397 .00401 00406 .00412 .00420 .00430
1/4 .00451 .00455

.
.00461 .00467 .00475
. .00485
If it is impossible to obtain a straight edge on A scriber must never be used for drawing lines
a sheet to start a layout , or if the distance from on aluminum or magnesium except to indicate
the edge is too great , a reference line may be where the metal is to be cut or drilled . All other
used . The reference line may be made by lines must be drawn with a soft -lead pencil.
connecting any two points with a straight line. Folding a piece of metal along a sharp line made
Perpendiculars may be erected to the reference with a scriber will weaken the metal and
line by using a compass or dividers, thus forming possibly cause it to crack along the bend . If it
a cross. Once the cross is accurately laid out , it does not crack at the time of bending, it is very
may be used as a basis for almost any type of susceptible to cracking in service, possibly at a
fitting layout . time when failure of the part can be cata
strophic.
118
CHAPTER 6
AIRCRAFT HARDWARE
Aircraft hardware is a term used in reference SOLID RIVETS

to a great many items used in aircraft construc
tion . Some hardware, such as electrical and Solid rivets are classified by their head shape ,
powerplant hardware , is not applicable to the by the material from which they are manu
AMS rating. The AMS is concerned with such factured, and by their size . Rivet head shapes
hardware as rivets, turnlock fasteners, bolts, and their identifying code numbers are shown in
screws, nuts , washers, wire and cables, and figure 6-1 . The prefix MS identifies hardware
related hardware . under the cognizance of the Department of
Because of the small size of most hardware Defense and the item conforms to written
items , their importance is often overlooked ; military standards. The prefix AN identifies
however , the safe and efficient operation of any specifications which are developed and issued
aircraft is greatly dependent upon correct selec under joint authority of the Air Force-Navy .
tion and use of aircraft structural hardware . This Countersunk-head rivets. Countersunk-head
chapter discusses these various items , and pro rivets, often referred to as FLUSH RIVETS , are
vides information which will aid in the selection used where streamlining is important. On com
and correct use of aircraft structural hardware . bat aircraft, practically all external surfaces are
flush riveted . Countersunk-head rivets are ob
tainable with heads having an included angle of
RIVETS 78 and 100 degrees. The 100 -degree is the most
commonly used type.
Every AMS should be a skilled riveter. The Universal-head rivets. Universal-head rivets
fact that there are hundreds of thousands of offer only slight resistance to airflow and are,
rivets in the airframe of some of our late model therefore, frequently used on external surfaces,
tactical aircraft is an indication of how im especially on helicopters, transports , and other
portant riveting is in the work of the AMS . A low -speed aircraft where aerodynamic smooth
glance at any aircraft will disclose the thousands ness is not of prime importance.
of rivets in the outer skin alone . In addition to
the riveted skin , rivets are also used for joining Rivet Identification Code
spar sections , for holding rib sections in place ,
for securing fittings to various parts of the The rivet codes as shown in figure 6-1 are
aircraft, and for fastening innumerable bracing sufficient to identify rivets only as to head
members and other parts together. Rivets that shape . To be meaningful and precisely identify a
are satisfactory for one part of the aircraft are rivet , certain other information is encoded and
often unsatisfactory for another part . It is added to the basic code.
therefore important that the AMS know the A letter or letters following the head -shape
strength and driving properties of the various code identify the material or alloy from which
types of rivets and how to identify them as well the rivet was made . ( Table 6-1 includes aa listing
as how to drive or otherwise install them . of the most common of these codes.) The alloy
119
code is followed by two numbers separated by a are relatively soft and easy to drive. The cold
dash . The first number is the numerator of a work resulting from driving increases their
fraction which specifies the shank diameter in strength slightly. The 1100-F rivets are used
thirty -seconds of an inch. The second number is only for riveting nonstructural parts. These
the numerator of a fraction in sixteenths of an rivets are identified by their plain head . (See
inch and identifies the length of the rivet. The table 6-1 . )
rivet code is illustrated in figure 6-2 . Alloy 2117 rivets. Like the 1100-F rivets,
these rivets need no further treatment when
Rivet Composition received from the manufacturer, and can be
stored indefinitely . They are furnished in the
.
Most of the rivets used in aircraft construc solution-heat-treated (T4) temper, but will
tion are made of aluminum alloy. A few types, change to the solution -heat-treated -and -cold
used for special purposes, are made of mild steel , worked (T3 ) temper after driving. The 2117-14
Monel, titanium , and copper. Of the aluminum rivet is in general use throughout aircraft struc
alloy rivets, those made of 1100 , 2117 , 2017 ,> tures and is by far the most widely used rivet,
2024 , and 5056 are considered standard . (See especially in repair work . In most cases the
table 3-4 inch . 3 for composition of various 2117-T4 rivet may be substituted for 2017-14
alloys.) and 2024- T4 rivets for repair work by using the
Alloy 1100 rivets. Alloy 1100 rivets are next larger diameter of rivet. This is desirable
supplied in the “ as fabricated ” (F) temper and since both the 2017 - T4 and 2024-14 rivets must
are driven in this condition . No further treat be heat treated prior to using , or kept in cold
ment is required and the rivet properties do not storage . The 21 17-14 rivets are identified by a
change with prolonged periods of storage . They dimple in the head .
Alloy 2017 and 2024 rivets . As mentioned in
the preceding paragraph , both these rivets are
supplied in the T4 temper and must be heat
treated . These rivets must be driven within 20
minutes after quenching or refrigerated at 32° F
M
TI AN 470
MS 20470
UNIVERSAL
AN 426
MS20426
COUNTERSUNK
or lower which will delay the aging time 24
hours . If either time is exceeded , reheat treat
ment is required . These rivets may be reheated
as many times as desirable provided the proper
solution heat-treatment temperature is not
exceeded . The 2024- T4 rivets are stronger than
the 2017 -T4 and are therefore harder to drive.
The 2017- T4 rivet is identified by the raised teat
AM.311
on the head, while the 2024 - T4 has two raised
Figure 6-1 .-Rivet head shapes and code numbers. dashes on the head .
Alloy 5056 rivets. These rivets are used
primarily for joining magnesium alloy structures
because of their corrosion resistant qualities
MS 20 426 AD 5 - 8
Length in sixteenths (8 / 16ths when used with magnesium. They are supplied
of an inch ) .
in the H32 temper (strain-hardened and then
Diameter in thirty - seconds ( 5 / 32nds
of an inch ) . stabilized ). These rivets are identified by a raised
Material or alloy (2117-T4) . cross on the head. 5056-H32 rivets may be
-Head shape ( countersunk ). stored indefinitely with no change in driving
characteristics.
-Specification (Military
Standard ) .
HI-SHEAR RIVETS
AM.312 Hi-shear (pin) rivets are essentially threadless
Figure 6-2 . - Rivet coding example. bolts. The pin is headed at one end and is
120
Chapter 6 -AIRCRAFT HARDWARE
Table 6-1 . - Rivet material identification .
Material or Code letters Head marking

alloy on rivet
1100 -F А Plain
Oil
2117 - T4 AD Indented
dimple
-
-
-
-
-
1
|
2017 -T4 D Raised
teat
1
1
1
1
1
1
2024-14 DD Raised
double
dash
1
5056 -H32 B Raised
cross
grooved about the circumference at the other. A inch for the diameter and sixteenths of an inch
metal collar is swaged onto the grooved end , for the rivet grip length. Thus an NAS 1055-5-7
effecting a firm tight fit. They are available in rivet would be a Hi-Shear rivet with a counter
two head styles , the flat protruding head and the sunk head, its diameter would be 5 /32-inch, and
flush 100 -degree countersunk head . Hi-Shear its maximum grip length would be 7 / 16 -inch .
rivets are made in a variety of materials and are The collars are identified by a basic code
used only in shear applications. Due to the shear number and a dash number which corresponds
strength being greater than either the shear or to the dash number for the diameter of the rivet .
bearing strength of aluminum alloys, they are An A before the dash number indicates an
used to greater advantage only in the thicker aluminum alloy collar. An NAS528-A5 collar
gage sheets. They are never used where the grip would be used on a 5 /32-inch diameter rivet pin.
length is less than the shank diameter. Hi-Shear Repair procedures involving the installation or
rivets are illustrated in figure 6-3 . replacement of Hi-Shear rivets generally specify
the collar to be used.
Rivet Identification
BLIND RIVETS
Hi-Shear rivets are identified by code numbers
similar to the solid rivets. The size of the rivet is There are many places on an aircraft where
measured in increments of thirty -seconds of an access to both sides of a riveted structural part is
코 GROOVE
SHEARING
EDGE
O
FLUSH HEAD FLAT HEAD COLLAR

RIVET RIVET
AM.295
Figure 6-3 . - Hi- Shear rivet installation .
121
impossible, or where limited space does not same principle as the friction lock rivets, both
permit the use of a bucking bar . Furthermore, in employing a mandrel stem and a hollow shank .
the attachment of many non -structural parts, The main difference between the friction lock
such as aircraft interior furnishings, flooring, and mechanical lock rivets is in the method of
deicing boots , flotation equipment , and the like, pin retention ; the friction lock relies on friction
the full strength of solid shank rivets is not alone for pin retention , while the mechanical
necessary and their application would add extra lock rivet employs a mechanical lock between
weight to the aircraft thereby reducing the the head of the rivet and the pull stem . Note in
payload . view B that the collar, shown clearly in view A
For use in such places , rivets have been attached to the head , has been driven into the
designed which can be formed from the outside.. head and has assumed a wedge or cone shape
They are lighter than solid shank rivets , yet around the groove in the pin . This holds the
amply strong . These rivets are manufactured by shank firmly in place from the head side.
various corporations and have characteristic The self-plugging rivet is made of 5056 -H14
peculiarities , chief of which is the requirement aluminum alloy and includes the conical recess
of special installation tools. Rivets in this cate and locking collar in the rivet head . The stem is
gory are commonly referred to as blind rivets made of 2024 - T36 aluminum alloy . Pull grooves
because of the self-heading feature. which fit into the jaws of the rivet gun are
Self -Plugging Rivet . The self -plugging rivet provided on the stem end that protrudes above
( friction lock ) retains the stem in position by the rivet head. The blind end portion of the
friction . The stem is drawn up into the rivet stem incorporates a head and a land with an
shank and the mandrel portion of the stem extruding angle which expands the rivet shank .
upsets the shank on the blind side , forming a Applied loads permissible for self-plugging
plug in the hollow center of the rivet . The excess rivets are comparable to those for solid shank
portion of the stem breaks off at a groove due to rivets of the same shear strength , regardless of
the continued pulling action of the rivet gun or sheet thickness. The composite ultimate shear
tool. The two styles or rivet heads are the strength of the 5056-H14 shank and the
universal and the 100 -degree countersunk . These 2024 - T36 pin exceeds 38,000 psi on standard
correspond to the MS20470 and MS20426 solid rivet hole diameter ; their tensile strength is in
rivets , respectively . Materials used are 21 17-14 excess of 28,000 psi . Pin retention charac
and 5056-F aluminum alloys , and Monel for teristics are excellent in these rivets and the
special application . The shank diameter and grip possibility of the pin working out is minimized
lengths are designated by dash numbers after the by the lock formed in the rivet head .
basic number. The first dash number indicates Rivnuts. The Rivnut is a hollow rivet made of
the shank diameter in thirty -seconds of an inch 6063 aluminum alloy , counterbored and
and the second number indicates the grip length threaded on the inside . Installation is ac
in sixteenths of an inch. The material code is the
same as for solid rivets.
Table 6-2 . - Rivet types with basic numbers.
Pull-Through Rivets . Pull -through rivets are
essentially the same as the self-plugging rivets,
except that when the mandrel pulls on the stem,
CONFIGURATION HEAD BASIC NUMBER
the stem forms the head on the rivet shank , then TYPE
IDENTIFICATION
pulls all the way through the shank , leaving a 100 DEGREE
MS20601
hole in the rivet . COUNTERSINK
SELF PLUGGING
The same installation tools are used for the UNIVERSAL
MS20600
HEAD
self-plugging ( friction lock) and pull -through
rivets. Table 6-2 shows the basic rivet types with
IT
100 DEGREE
MS20605
COUNTERSINK
basic numbers. Figure 6-4 illustrates the installa HOLLOW
PULL THRU
tion of both types of rivets . UNIVERSAL
HEAD
MS20604
Self-Plugging rivets (mechanical lock). Figure

6-5 illustrates a blind rivet that operates on the
122
INSTALLATION
TOOL
SELF PLUGGING
RIVET
쟁
工业显。 SELF PLUGGING
RIVET STEM
TRIMMED
INSTALLATION
TOOL
HOLLOW PULL
THRU RIVET
RIVET INSTALLED
PULL THRU
AM.315
Figure 6-4 . - Self-plugging ( friction lock) and pull-through rivet installation.
complished with the aid of aa special tool , which indicate the nominal diameter and the actual
heads the rivet on the blind side of the work . number of threads per inch of the machine
Rivnuts are primarily used as a nut plate , as in screw that fits into the Rivnut . Rivnuts are
the attachment of deicer boots ; however, they available with our without small projections,
may be used as rivets in secondary structures, or called keys , attached to the underside of the
for the attachment of accessories such as instru head to keep the Rivnut from turning. Keyed
ments, brackets, and soundproofing materials. Rivnuts are used when the Rivnut serves as a nut
After a suitable group of Rivnuts has been plate , while Rivnuts without keys are used for
installed, accessories can be fastened in place straight blind riveting jobs where no torque
with screws . loads are imposed.
Rivnuts are manufactured in two head styles, Open-end Rivnuts are the most widely used
flat and countersunk , and in two shank designs, and are recommended in preference to the
open and closed ends, as shown in figure 6-6 . closed end type , except in sealed flotation or
Each of these rivets is available in three sizes, pressurized compartments, in which cases the
Nos. 6-32 , 8-32, and 10-32 . These numbers closed -end Rivnut must be used .
123
Blind Lockbolt . The blind lockbolt shown in

figure 6-7 ( B) is similar to the self-plugging rivet
shown in figure 6-5 . It features a positive
mechanical lock for pin retention.
LOCKING TURNLOCK FASTENERS

COLLAR
NOTE SHEET
GAP Turnlock fasteners are used to secure inspec
LOCKING COLLAR
tion plates , doors , and other removable panels
on aircraft. Turnlock fasteners are also referred
to by such terms as quick -opening, quick -action ,
and stressed -panel fasteners. The most desirable
feature of these fasteners is that they permit
quick and easy removal of access panels for
I inspection and servicing purposes. Removal and
( A ) INSERTED ( B ) INSTALLED
LOCKBOLT PIN
AM.316
Figure 6-5 . - Self-plugging rivet ( mechanical lock) .
LOCKBOLT FASTENERS
Lockbolt fasteners are designed to meet high

strength requirements. Used in many structural
homo
applications, their shear and tensile strengths
equal or exceed the requirements of AN and
NAS bolts .
Lockbolt Pins (tension pull type ). The lock
bolt shown in figure 6-7 (A) consists of a pin
and collar. They are available in two head styles,
protruding and countersunk . Pin retention is
accomplished by swaging the collar into the
locking grooves on the pin .
COUNTERSUNK FLAT HEAD
COLLAR
)
A
(
(
B
)
OPEN END OPEN END

CLOSED END CLOSED END
AM.317
Figure 6-6 . - Sectional view of Rivnut showing head AM.297
and end designs. Figure 6-7 . - Lockbolts.
124
Chapter 6-AIRCRAFT HARDWARE
replacement of damaged turnlock fasteners is sembly . (See fig . 6-8 . ) The receptacle consists of
one of the responsibilities of the AMS. an aluminum alloy forging mounted in a
Turnlock fasteners are manufactured and stamped sheetmetal base. The receptacle as
supplied by a number of manufacturers under sembly is riveted to the access door frame,
various trade names. Some of the most common which is attached to the structure of the aircraft .
ly used are the Dzus (pronounced zoo '-s ), The grommet is a sheet-metal ring held in the
Camloc, and Airloc, all of which are discussed in access panel with the retaining ring . Grommets
the following sections . are furnished in two types, the flush type and
the protruding type. In addition to serving as a
CAMLOC FASTENERS grommet for the hole in the access panel , it also
holds the stud assembly . The stud assembly
The 4002 series Camloc fasteners consist of consists of a stud, a cross pin, spring, and a
>
four principal parts , the receptacle , the spring cup. The assembly is so designed that it
grommet, the retaining ring , and the stud as can be quickly inserted into the grommet by
OUTER MEMBER
STUD ASSEMBLY
STUD ASSEMBLY GROMMET

GROMMET
RETAINING
RING
RIVET
FLUSH OR
PROTRUDING
GROMMET
INNER
MEMBER
RECEPTACLE
GROMMET -STUD
RETAINING RETAINING
RING RING
PROTRUDING TYPE INSTALLATION
STUD RETAINING
RING ( USED ON OUTER MEMBER
SOME FASTENERS) STUD ASSEMBLY
GROMMET
GROMMET
RETAINING
RECEPTACLE RING
RIVET
INNER
MEMBER
RECEPTACLE
FLUSH TYPE INSTALLATION
AM.38
Figure 6-8. -Camloc 4002 series fastener .
125
compressing the spring . Once installed in the studs are held in the panel with flat or cone
grommet, the stud assembly cannot be removed shaped washers , the latter being used with flush
unless the spring is again compressed . fasteners in dimpled holes . This fastener may be
distinguished from screws by the deep No. 2
CAMLOC HIGH-STRESS Phillips recess in the stud head and by the
PANEL FASTENERS bushing in which the stud is installed .
A threaded insert in the receptacle provides
The Camloc high-stress panel fastener shown an adjustable locking device . As the stud is
in figure 6-9 is a high -strength , quick release, inserted and turned counterclockwise 1/2 turn
rotary type fastener and may be used on flat or or more , it screws out the insert sufficiently to
curved , inside or outside panels . The fastener permit the stud key to engage the insert cam
may have either a flush or protruding stud . The when turned clockwise . Rotating the stud
2
6
2
-4 9
10
-5
JO
AM.39
1. Tension spring. 6. Receptacle attaching rivets.
2. Stud assembly . 7. Outer skin .
3. Bushing. 8 Inner skin.
4. Retaining ring. 9. Insert
5. Receptacle assembly. 10. Cover.
Figure 6-9 . - Camloc high -stress panel fastener.
126
Chapter 6 - AIRCRAFT HARDWARE
clockwise 1/4 turn engages the insert , and pin . The receptacle is riveted to the access panel
continued rotation screws the insert in , tighten frame.
ing the fastener. Turning the stud 1/4 turn Two types of Airloc receptacles are available ,
counterclockwise will release the stud , but will
> the fixed type (insert A) and the floating type
not screw the insert out far enough to permit (insert B) . The floating type makes for easier
reengagement on installation . The stud should alignment of the stud in the receptacle. Several
be turned at least 1/2 turn counterclockwise to types of studs are also available , but in each
reset the insert. instance the stud and cross pin come as separate
units so that the stud may be easily installed in
AIRLOC FASTENERS the access panel .
The Airloc receptacle is fastened to the inner
Figure 6-10 illustrates the parts that make up surface of the access panel frame by two rivets.
an Airloc fastener. As with the Camloc fastener, Rivet heads must be flush with the outer surface
the Airloc fastener also consists of a receptacle , of the panel frame. When replacing receptacles,
a stud , and a cross pin . The stud is attached to drill out the two old rivets and attach the new
the access panel and is held in place by the cross receptacle by flush riveting. Be careful not to
FIXED TYPE FLOATING TYPE

( A) (8)
RECEPTACLE CROSS PIN
11
al PANEL STUD
Figure 6-10.-Airloc fastener.
127
AM.40
mar the sheet. When inserting the stud and cross Figure 6-11 shows the parts making up a
pin , insert the stud through the access panel and, light-duty Dzus fastener. Notice that they
by use of a special handtool, insert the cross pin include a spring and a stud . The spring is made
in the stud . Cross pins can be removed by means of cadmium-plated steel music wire and is
of special ejector pliers. usually riveted to an aircraft structural member.
The stud comes in a number of designs ( as
DZUS FASTENERS shown in insets A , B , and C) and mounts in a
>
dimpled hole in the cover assembly.

Dzus fasteners are available in two types. One When the panel or plate is being positioned on
is the light-duty type, used on box covers , access the aircraft preparatory to securing it in place,
hole covers , and lighweight fairing. The second is the spring riveted to the structural member
the heavy-duty type, which is used on cowling enters the hollow center of the stud , which is
and heavy fairing. The main difference between retained in the plate or panel . Then , when the
the two types of Dzus fasteners is a grommet, stud is turned about 1/4 turn , the curved jaws of
used by heavyduty but not by light-duty the stud slip over the spring and compress it.
fasteners. Otherwise their construction features The resulting tension locks the stud in place
are about the same. thereby securing the panel or plate .
С
D
OVAL
TYPE
FLUSH
TYPE WING
TYPE
les
STUD
SPRING
MID -
COVER DIMPLED
ASSEMBLY HOLE
AM.319
Figure 6-11. - Dzus fastener.
128
THREADED FASTENERS in the case of flat-end bolts (fig.6-12 ) or in the

case of chamfered (rounded ) end bolts , at least
BOLTS one full chamfer should extend through the nut.
If the bolt is too short , it may not extend out of
Many types of bolts are used on aircraft and the bolthole far enough for the nut to be
each type is used to fasten something in place. securely fastened . If it is too long, it may extend
However, before discussing some of these types, so far that it interferes with the movement of
it might be helpful at this point to list and nearby aircraft parts. Unnecessarily long bolts,
explain some commonly used bolt terms. The especially in numbers, can affect weight and
AMS should know the names of bolt parts. He balance and reduce the aircraft payload
should also be aware of the bolt dimensions that capacity .
must be considered in selecting a bolt. Figure In addition, if a bolt is too long or too short,
6-12 illustrates both types of information . its grip will usually be the wrong length . As
The three principal parts of a bolt are the shown in figure 6-13 , grip length should be
HEAD , THREAD , and GRIP . It is possible that approximately the same as the thickness of the
two of these parts are well known but perhaps material to be fastened . If the grip is too short,
the “ grip ” is an unfamiliar term. If so , notice the threads of the bolt will extend into the
that the grip is the unthreaded part of the bolt bolthole and may act like a reamer when the
shaft and that it extends from the threads to the material is vibrating . To prevent this, make
bolthead . The head is the larger diameter of the certain that no more than two threads extend
bolt and may be one of many shapes or designs. into the bolthole . Also make certain that any
The head retains the bolt in place in one threads that enter the bolthole extend only into
direction and the nut used on the threads retains the thicker member that is being fastened . If the
it in the other direction. grip is too long , the nut will run out of threads
In order to choose the correct replacement before it can be tightened. In this event a bolt
for an unserviceable bolt , several bolt with a shorter grip should be used, or if the bolt
dimensions must be considered , one being the grip extends only a short distance through the
length of the bolt . As shown in figure 6-12 , the hole , a washer may be used .
bolt length is the distance from the tip of the A second bolt dimension that must be con
threaded end to the head of the bolt . Correct sidered is diameter. As shown in figure 6-12, the
length selection is indicated when the chosen diameter of the bolt is the thickness of its shaft .
bolt extends through the nut at least 1/32 inch If this thickness is 1/4 inch or more, the bolt
diameter is usually given in such fractions of an
inch as 1/4, 5/16, 7/16, 1/2 , and the like.
LENGTH
However, if the bolt is less than 1/4 inch thick ,
the diameter is usually expressed as a whole
WIDTH
-HEAD
number. For instance, a bolt that is 0.190 inch

in diameter is called a No. 10 bolt , while aa bolt
that is 0.164 inch in diameter is called a No. 8 .
DIA METER
The results of using a wrong-diameter bolt
THICKNESS
should be obvious. If the bolt is too big, it

HEAD
cannot of course enter the bolthole. If the

THREADS GRIP diameter is too small , the bolt has too much
play in the bolthole, and the chances are that it
is not as strong as the correct size of bolt .
The third and fourth bolt dimensions that
should be considered when choosing bolt
replacement are head thickness and width . If the
head is too thin or too narrow , it may not be
AM.320 strong enough to bear the load imposed on it. If
Figure 6-12. - Bolt terms and dimensions. the head is too thick or too wide, it may extend
129
So far that it interfers with the movement of Boltheads

adjacent aircraft parts.
The most common type of head is the hex
nead, shown in figure 6-12. This type of head
may be thick for greater strength or relatively
thin in order to fit in places having limited
clearances. In addition , the head may be
TIT common or drilled . A hex head bolt may have a
single hole drilled through it between two of the
sides of the hexagon and still be classed as a
common . The drilled head hex bolt has three
holes drilled in the head , connecting opposite
sides of the hex .
(
)
A
BOLT GRIP LENGTH CORRECT
CD EYE BOLT
CM ‫ רוח‬:
BOLT GRIP LENGTH TOO SHORT

( B)
( 0)) CLOSE TOLERANCE BOLT
( C)
INTERNAL WRENCHING BOLT
(D )
BOLT GRIP LENGTH TOO LONG CLEVIS BOLT
AM.321 AM.322
Figure 6-13. - Correct and incorrect grip lengths. Figure 6-14 . - Boltheads.
130
Four additional types of boltheads are shown Bolt Material

in figure 6-14 . Notice that panel A in that
The type of metal used in an aircraft bolt
illustration shows an eyebolt , often used in helps to determine its strength and its resistance
flight control systems. Panel B shows a counter to corrosion . Therefore, make certain that mate
sunk head , close tolerance bolt. Panel C shows rial is considered in the selection of replacement
an internal wrenching bolt . Both the counter bolts. Like solid shank rivets, bolts have
sunk head bolt and the internal wrenching bolts distinctive head markings that help to identify
have hexagonal recesses (six -sided holes) in their
the material from which they are manufactured.
heads. They are tightened and loosened by use
of appropriate size, Allen wrenches. Panel D In certain cases, aircraft manufacturers are
compelled to make bolts of different dimensions
shows a clevis bolt with its characteristic round
or greater strength than the standard types. Such
head. This head may be slotted , as shown , to bolts are made for a particular application and it
receive a common screwdriver or recessed to
receive a Reed and Prince or a Phillips screw is of extreme importance that like bolts are used
driver . in replacement . Such special bolts are usually
identified by the letter S stamped on the head.
Bolt Threads
Figure 6-15 shows the tops of several hex-bolt
heads , each marked to indicate the type of bolt
material .
Another structural feature in which bolts may
differ is threads . These usually come in one of Bolt Identification
the two types-coarse or fine, and the two are
not interchangeable . For any given size of bolt Unless current directives specify otherwise,
there are a different number of coarse and fine every unserviceable bolt should be replaced with
threads per inch . For instance , consider the a bolt of the same type . Of course , substitute
1 / 4 -inch bolts. Some are called 1 /4-28 bolts, and interchangeable items are sometimes
because they have 28 fine threads per inch . available , but the ideal fix is a bolt - for-bolt
Others have only 20 coarse threads per inch and replacement . The part number of a needed bolt
are called 1 /4-20 bolts. To force one size of may be obtained by referring to the Illustrated
threads into another size even though both are Parts Breakdown (IPB ) for the aircraft con
1/4 inch will strip the finer threads or softer cerned . Exactly what this part number means
metal . The same thing is true concerning the depends upon whether the bolt is AN (Air
other sizes of bolts ; therefore, make certain that Force -Navy ), NAS (National Aircraft Standard )
bolts selected have the correct type of threads. or MS (Military Standard ).
HEAD MARKINGS
STEEL ALUMINUM CORROSION STEEL STEEL

CLOSE ALLOY RESISTANT ( 125,000 ( 160,000 TO
TOLERANCE ( 62,000 STEEL P.S.T.) 180,000
( 125,000 TO P.S.1. ) ( 125,000 P.S.I. )
145,000 A.S.I) P.S.I.)
AM.41
Figure 6-15 . - Bolthead markings.
131
case of a series number ending in 0, for instance

AIR FORCE BOLT SAFETYING AN30 , the O stands for 10, and the bolt has a
NAVY BOLT MATERIAL PROVISIONS diameter of 10/16 inch (5/8 inch).
Refer again to figure 6-16 and notice that a
dash follows the series number. When used in
the part numbers for general-purpose AN bolts,
clevis bolts, and eyebolts, this dash indicates
AN 4 - 20A that the bolt is made of carbon steel . With these
types of bolts, the letter C, used in place of the
dash, means corrosion -resistant steel ; the letter
DASH NUMBER
D means 2017 aluminum alloy ; and the letters
SERIES
NUMBER ( BOLT GRIP DD stand for 2024 aluminum alloy . For some
( CLASS AND AND LENGTH ) bolts of this type , a letter H is used with these
DIAMETER )
letters or with the dash . If it is so used , the H
>
shows that the bolt has been drilled for safety

AM.323 ing .
Next , notice the number 20 that follows the
Figure 6-16 . - AN bolt part number breakdown.
dash. This is called the dash number, and it
represents the bolt's grip (as taken from special
AN PART NUMBER . - There are several tables ). In this instance the number 20 stands
for a bolt that is 2 1/32 inches long.
classes of AN bolts, and in some instances their
The last character in the AN number il
part numbers reveal slightly different types of
information . However,
However , most AN numbers lustrated in figure 6-16 is the letter A. This
signifies that the bolt is not drilled for cotter pin
contain the same type of information . safetying. If no letter were used after the dash
Figure 6-16 shows a breakdown of a typical number, the bolt shank would be drilled for
AN bolt part number. Like the AN rivets safetying.
discussed earlier, it starts with the letters AN. NAS PART NUMBER . - Another series of
Next , notice that a series number follows the bolts used in aircraft construction is the
letters AN . This number usually consists of two National Aircraft Standard (NAS) . (See fig.
digits, and the first digit (or absence of it) shows 6-17 .) In considering one of the NAS bolts,
the class of the bolt . For instance, in figure 6-16 NAS144 ( special internal wrenching type),
the series number has only one digit, and the notice that the bolt identification code starts
absence of one digit shows that this part number with the letters NAS, which show , of course ,
represents a general-purpose hex-head bolt. that the code represents a National Aircraft
However, the part numbers for some bolts of Standard piece of hardware. Next , notice that
this class have two digits. In fact, general
purpose hex-head bolts include all part numbers
beginning with AN3 , AN4, and so on through
AN20 . Other series numbers and the classes of NAS 25
bolts that they represent are as follows: Dash number (bolt grip in
sixteenths ) .
AN21 through AN36 -clevis bolts . Diameter in sixteenths .
AN42 through AN49 - eyebolts.
Series number .
The series number shows another type of National Aircraft Standard
information besides bolt class. With a few bolt .
exceptions , it indicates bolt diameter in six

teenths of an inch. For instance, in figure 6-16
the last digit of the series number is 4, so this AM.324
bolt is 4/16 inch ( 1/4 inch) in diameter. In the Figure 6-17 . - NAS bolt part number breakdown.
132
Chapter 6- AIRCRAFT HARDWARE
the series has a three -digit number, 144. The HI-LOK FASTENERS
first two digits ( 14) show the class of the bolt .
The next number (4) indicates the bolt diameter The Hi- Lok fastener shown in figure 6-19
in sixteenths of an inch . The dash number (25 ) combines the features of a rivet and a bolt, and
indicates bolt grip in sixteenths . is used for high - strength , interference fit of
MS PART NUMBER . – Military Standard (MS) primary structures. The Hi-Lok fastener consists
is another series of bolts used in aircraft of a threaded pin and threaded locking collar.
construction. In considering the part number The pins are made of cadmium-plated alloy steel
shown in figure 6-18 , the MS indicates that the with protruding or 100 -degree flush heads.
bolt is a Military Standard bolt . The series Collars for the pins are made of anodized
number ( 20004 ) indicates the bolt class and 2024 - T6 aluminum or stainless steel . The
diameter in sixteenths of an inch ( internal threaded end of the pin is recessed with a
wrenching, 1 /4-inch diameter ). The letter H hexagon socket to allow installation from one
before the dash number indicates that the bolt side . The major diameter of the threaded part of
has a drilled head for safetying. The dash the pin has been truncated ( cut undersize ) to
number (9 ) indicates the bolt grip in sixteenths accomodate a 0.004- inch maximum interference
of an inch . fit. One end of the collar is internally recessed
with a 1 /16 - inch , built-in variation which auto
matically provides for variable material thickness
MS 20004 H 9 without the use of washers and without preload
changes . The other end of the collar has a
Dash number (bolt grip in
sixteenths ) . torque -off wrenching device which controls a
predetermined residual tension of preload
Safetying provisions. ( 10 % ) in the fastener.
Series number ( class and diameter
in sixteenths ) .
HELI -COIL INSERTS
Military Standard bolt .
Heli-Coil thread inserts are primarily designed

AM.298 to be used in materials which are not suitable for
Figure 6-18 . -MS bolt part number breakdown. threading because of their softness. They are
000001
HI - LOK COLLAR
HI - LOK PIN HI - LOK PIN

HI - LOK FASTENER PROTRUDING 100 FLUSH
INSTALLATION HEAD TYPE HEAD TYPE
AM.325
Figure 6-19 . - Hi-Lok fastener.
133
Tang Opposite External Threads

End
Internal
Threads
Grip
Coil
PLAIN MID -GRIP
CROSS SECTION APPLICATION
HELI - COIL HELI- COIL
AM.326
Figure 6-20.-Heli-Coil inserts.
made of a dianiond cross -sectioned stainless steel a gripping effect on the engaging screw . For
wire which is helically coiled and , in its finished quick identification, the self-locking mid -grip
form , is similar to a small spring which has been inserts are dyed red .
fully compressed . There are two types of Heli
Coil inserts. (See fig. 6-20 . ) One is the plain
insert, made with a tang that forms a portion of
> JO -BOLT FASTENERS
the bottom coil offset, and is used to drive the
insert. This tang is left on the insert after The Jo -Bolt shown in figure 6-21 is a high
installation, except when its removal is necessary strength , blind , structural fastener that is used
to provide clearance for the end of the bolt . The on difficult riveting jobs when access to one side
tang is notched to provide for the breakoff from of the work is impossible. The Jo - Bolt consists
the body of the insert , thereby providing full of three parts: an aluminum alloy or alloy steel
penetration for the fastener. nut , a threaded alloy steel bolt , and a corrosion
The second type of insert used is the self resistant steel sleeve, which are factory pre
locking mid -grip insert which has a specially assembled. The head styles available for Jo-Bolts
formed grip coil midway of the insert, producing are the 100 -degree flush head, hexagon
-BOLT
Huweliwal
NUT
‫المسلسلنا‬
COLLAR
INSTALLED PROTUDING HEAD INSTALLED FLUSH HEAD
AM.327
Figure 6-21. - Jo -Bolts.
134
protruding head , and the 100 -degree flush milla PLAIN HEX NUT. - The plain hex nut is of
ble head . rugged construction . This makes it suitable for
carrying large tensional loads. However, since it
AIRCRAFT NUTS requires an auxiliary safetying device, such as a
checknut or lock washer, its use on aircraft
Aircraft nuts differ in design and material just structures is somewhat limited .
as bolts do , in that they are designed to do a LIGHT HEX NUT . - The light hex nut is a
specific job with the bolt . For instance , some of nuch lighter nut than the plain hex nut and must
the nuts are made of cadmium -plated carbon be locked by an auxiliary device. It is used for
steel , stainless steel, brass , or aluminum alloy . miscellaneous light-tension requirements.
The type of metal used is not identified by CHECKNUTS . - The checknut is employed as
markings on the nuts themselves. Instead , the a locking device for plain nuts , setscrews,
material must be recognized from the metallic threaded rod ends , and other devices.
luster of the metal . WINGNUTS. - Wingnuts are intended for
Nuts also differ greatly in size and shape . In places where the desired tightness can be
spite of these many and varied differences they obtained by use of the fingers and where the
all fall under one of two general groups - self assembly is frequently removed , such as battery
locking and nonself-locking. Nuts are further terminal connections . In the illustration , note
divided into types such as plain nuts, castle nuts, the hole in one of the wings, which is used for
checknuts, plate nuts, channel nuts, barrel nuts , safetying the nut with wire .
internal wrenching nuts , external wrenching
>
nuts , shear nuts , sheet spring nuts , and wingnuts. Self -Locking Nuts
Each of these groups is discussed in subsequent Self- locking nuts provide tight connections
paragraphs and sections. which will not loosen under vibrations. Self
locking nuts approved for use on aircraft meet
Nonself -Locking Nuts
Nonself -locking nuts require the use of a
separate locking device for security of installa
tion . There are several types of these locking
devices which are mentioned in the following
paragraphs in connection with the nuts on which
they are used . Since no single locking device can
be used with all types of nonself-locking nuts,
the AMS must select one suitable for the type of
nut being used . Figure 6-22 illustrates four CASTLE NUT PLAIN NUT
nonself-locking nuts .
CASTLE NUT. - The castle nut is used in
conjunction with drilled -shank bolts, hex-head
bolts, clevis bolts , eyebolts, and drilled head
studs. It is fairly rugged and can withstand large
tensional loads. Slots ( called castellations ) in the
nut are designed to accommodate a cotter pin or
lock wire for safetying purposes.
CASTELLATED SHEAR NUT . - The castel
lated shear nut is designed for use with devices
such as drilled clevis bolts and threaded taper May
pins which are normally subjected to shearing CASTELLATED
WING NUT
stress only . Like the castle nut , it is castellated SHEAR NUT
for safetying, but is not as deep nor as strong as AM.42

the castle nut . Figure 6-22 -Nonself-locking nuts.
135
critical specifications as to strength, corrosion ends must not be used. Bolts, studs , and screws
resistance, and temperatures. The two general of 1/4 inch or less with cotter pin holes shall not
types of self-locking nuts are the all-metal nuts be used with self-locking nuts. Bolts, studs, and
and metal nuts with a nonmetallic insert to screws over 1/4 inch in diameter may be used
provide the locking action . New self-locking nuts with self-locking nuts, provided the cotter pin
must be used each time components are installed holes are free from burrs.
in critical areas throughout the entire aircraft, Used self-locking nuts are generally suitable
including all flight, engine, and fuel control for reuse in noncritical applications provided the
linkage and attachments. The Boots and the threads have not been damaged and are in a
Flexloc are examples of the all -metal type; the serviceable condition and if the locking material
Elastic Stop is an example of the nonmetallic is not damaged or permanently distorted .
insert type . Figure 6-23 shows several types of NOTE : If any doubt exists about the condi
self-locking nuts. tion of the nut, replace it with a new one .
The Boots self-locking nut is of one -piece When anchoring lightweight parts the sheet
all -metal construction , designed to hold tight in spring nut (fig . 6-24) is used . Applications
spite of severe vibration . It has two sections include supporting line clamps , electrical equip
connected by a spring which is an integral part ment , small access doors , etc. It is made of sheet
of the nut . This load - carrying and locking nut is spring steel , cut so as to have two flaps. The
so spaced that the two sets of threads are out of ends of these flaps are notched to form a hole
phase - that is , so spaced that a bolt which has that is somewhat smaller in diameter than the
been screwed through the load -carrying section screw used . The sheet spring nut has a definite
must push the locking section outward against arch which tends to flatten out as the screw
the force of the spring in order to engage the pulls the flaps in toward the threads. This
threads of the locking section properly . Thus , flattening action forces the flaps of the nut
the spring, through the medium of the locking tightly into the threads of the screw , and the
section, exerts a constant locking force on the springiness of the sheet spring nut pushes
bolt in the same direction as a force that upward on the screw threads, binding them and
tightens the nut . The nut can be removed and locking the screw in place. With the sheet spring
used again without impairing its efficiency. nut, either a standard or a sheet -metal self
Other types of all-metal self-locking nuts are tapping screw is used .
constructed with the threads in the load - carrying
portion of the nut out of phase with the threads
in the locking portion, or with a saw cut top WASHERS
portion with a pinched -in thread. The locking
action of these types depends upon the
resiliency of the metal when the locking section Washers used in aircraft structures may be
and load -carrying section are forced into align grouped into three general classes - PLAIN
ment when engaged by the bolt or screw washers, LOCKWASHERS, and SPECIAL
threads. washers. Figure 6-25 shows some of the most
The Elastic Stop nut is constructed with a commonly used types.
nonmetallic (nylon) insert which is designed to Plain washers are widely used under nuts to
lock the nut in place . The insert is unthreaded provide a smooth bearing surface, to act as a
and has a smaller diameter than the nut proper. shim in obtaining the correct relationship be
When a screw or bolt is inserted, contact tween the threads of the bolt and the nut , and
between the bolt or screw threads and the insert to adjust the position of castellated nuts with
produces the locking action . The Elastic Stop respect to drilled cotter pin holes in bolts. Plain
nut is a low -temperature nut and must not be washers are also used under lockwashers to
subjected to temperatures above 250° F. prevent damage to surfaces of soft materials.
There are certain precautions which must be Lockwashers are used with plain nuts when
observed with all self -locking nuts. Bolts, studs, self-locking or castellated type nuts are not
and screws with damaged threads and rough applicable. Sufficient friction is provided by the
136
22
BOOTS AIRCRAFT NUT FLEXLOC NUT
TL
O O
NON - METALLIC ELASTIC ELASTIC TWO - LUG
INSERT STOP NUT ANCHOR NUT
LOCK NUT
11 BOOTS AIRCRAFT CHANNEL ASSEMBLY

O
O C
CM ELASTIC STOP NUT CHANNEL ASSEMBLY
AM.44
Figure 6-23 . - Self- locking nuts.
137
A B
ch
TOP VIEW SIDE VIEW
C INWARD D LOCK WASHERS

THREAD LOCK
OI
ARCHED
SPRING LOCK IBE
PLAIN BALL SOCKET TAPER PIN
DOUBLE- LOCKED
STARTING POSITION SPECIAL WASHERS
POSITION
AM.45
Figure 6-25. -Various types of washers.
AM.328
Figure 6-24 . - Sheet spring nut.
are used in conjunction with NAS internal
wrenching bolts . The washer used under the
spring action of the washer to prevent loosening head is countersunk to seat the bolthead / shank
of the nut from vibration . Lockwashers are not radius. A plain washer is used under the nut .
to be used on primary structures, secondary
structures, or accessories where failure might INSTALLATION OF
result in damage or danger to aircraft or person NUTS AND BOLTS
nel .
Special washers, such as ball- socket and seat Be certain that each bolt is of correct mate
washers, taper pin washers, and washers for rial. Examine the marking on the head to
internal-wrenching nuts and bolts , are designed determine whether a bolt is steel or aluminum
for special applications . alloy.
Ball- socket and seat washers are used in It is of extreme importance to use like bolts
applications where the bolt is installed at an in replacement. In every case, refer to the
angle to the surface, or where perfect alignment applicable Maintenance Instructions Manual and
with the surface is required at all times. These Illustrated Parts Breakdown .
washers are used together . Be sure that washers are used under both the
Taper pin washers are used in conjunction heads of bolts and nuts unless their omission is
with threaded taper pins and are installed under specified. A washer guards against mechanical
the nut to effect adjustment where a plain damage to the material being bolted and
washer would distort . prevents corrosion of the structural members.
Washers for internal-wrenching nuts and bolts An aluminum alloy washer should be used under
138
the head and nut of a steel bolt securing as bolts , but differ mainly in that they usually
aluminum alloy or magnesium members. Steel have a lower material strength , a looser thread
washers should be used when joining steel fit, and shanks threaded along their entire
members with steel bolts. length . However, several types of structural
Whenever possible the bolt should be placed screws are available which differ from structural
with the head on top or in the forward position . bolts only in the type of head ; the material is
This position tends to prevent the bolt from equivalent and there is a difinite grip . Screws
slipping out if the nut is accidentally lost . may be divided into four main groups
structural screws , machine screws , self-tapping
SAFETYING OF NUTS screws , and setscrews.
It is very important that all nuts , except the Structural Screws

self- locking type , be safetied after installation .
This prevents nuts from loosening in flight due Structural screws are used for assembly of
to vibration . Figure 6-26 illustrates the proper structural parts , as are structural bolts . They are
way to secure a nut using a cotter pin . made of alloy steel and are properly heat
treated . Structural screws have a definite grip
length ( fig . 6-27 ) and the same shear and tensile
strengths as the equivalent size bolt . They differ
from structural bolts only in the type of head .
These screws are available in round-head ,
1
countersunk-head, and brazier -head types , either
slotted or recessed for the various types of
screwdrivers .
Machine Screws
OPTIONAL PREFERRED
The commonly used machine screws are the
round -head , flat-head, fillister -head , pan -head,
>
AM.43 truss-head , and socket-head types.

Figure 6-26 . - Cotter pin installation. FLAT- HEAD MACHINE SCREWS.
Flat -head machine screws are used in counter
APPLICATION OF TORQUE sunk holes where a flush finish is desired . These
screws are available in 82 and 100 degrees of
Torque is the amount of twisting force head angle and have various types of recesses
applied when tightening a nut . If torque values and slots for driving.
are specified in the appropriate manual , a torque ROUND - HEAD MACHINE SCREWS.
wrench must be used . Regardless of whether Round-head machine screws are frequently used
torque values are specified or not , it is improtant in assembling highly stressed aircraft com
that all nuts in a particular installation be ponents.
tightened a like amount . This permits each bolt FILLISTER-HEAD MACHINE SCREWS.--
in a group to carry its share of the load. It is a Fillister-head machine screws are used as general
good practice, therefore, to use a torque wrench purpose screws and also may be used as cap
in all nut and bolt applications . screws in light applications such as the attach
ment of cast aluminum gearbox cover plates.
SCREWS SOCKET- HEAD MACHINE SCREWS.
Socket-head machine screws are designed to be
Screws are the most common type of screwed into tapped holes by internal wrench
threaded fasteners used on aircraft. They are ing. They are used in applications which require
similar to other types of threaded fasteners, such high strength precision products, compactness of
139
internal threads as it is turned into the hole in

which it is inserted. Self-tapping screws can be
used only in comparatively soft metals and
materials. Self-tapping screws may be further
divided into two classes or groups -machine
self-tapping screws and sheet-metal self-tapping
+ GRIP
screws .
Machine self-tapping screws are usually used

for attaching removable parts , such as name
-LENGTH plates , to castings. The threads of the screw cut
mating threads in the casting after the hole has
been predrilled undersize. Sheet-metal self
tapping screws are used for such purposes as
temporarily attaching sheet metal in place for
riveting and for permanent assembly of non
structural assemblies, where it is necessary to
insert screws in blind applications.
-GRIP
CAUTION : Self -tapping screws should never
be used to replace standard screws , nuts, or
LENGTH rivets in the original structure .
Setscrews
Setscrews are used to position and hold in

place components such as gears on a shaft .
Setscrews are available with many different
point styles. They are classified as hexagon
socket and fluted -socket headless set screws.
MISCELLANEOUS FASTENERS
GRIP
Some fasteners cannot be classified as rivets,
LENGTH : turnlocks, or threaded fasteners . Included in this
category are taper and flathead pins .
TAPER PINS
AM.329
Figure 6-27 . - Structural screws.
Taper pins ( fig. 6-28 (A) and (B)) are used in
joints that carry shear loads and where the
the assembled parts, or sinking of heads below absence of clearance is essential. The threaded
surfaces into holes . taper pin is used with a taper- pin washer and a
PAN -HEAD AND TRUSS -HEAD MACHINE shear nut if the taper pin is drilled or with a
SCREWS . - Pan -head and truss -head screws are self-locking nut if undrilled . When a shear nut is
general-purpose screws used where head height is used with the threaded taper pin and washer , the
unimportant . These screws are available with nut is secured with a cotter pin.
cross-recessed heads only.
FLATHEAD PINS
Self-Tapping Screws
The flathead pin is used with tie rod terminals
A self-tapping screw is one that cuts its own or secondary controls , which do not operate
140
SAFETYING MATERIAL
STATIONARY The AMS will come in contact with many

MEMBER А. different types of safetying materials. These
materials are used to stop rotation and other
-PLAIN movement of fasteners, and securing of other
TAPER equipment likely to come loose due to vibration
PIN
set up in the aircraft during flight operations .
MOVABLE
MEMBER COTTER PINS
Cotter pins are used to secure bolts , screws,

PLAIN TAPER PIN INSTALLED nuts, and pins. Some cotter pins are made of
low -carbon steel , while others consist of stainless
STATIONARY
MEMBER B steel and thus are more resistant to corrosion . In
-COTTER PIN addition , stainless steel cotter pins may be used
in locations where nonmagnetic material is
required . Regardless of shape or material, all
THREADED
cotter pins are used for the same general
-CASTELLATED
TAPER NUT purpose -- safetying. Figure 6-29 shows three
PIN types of cotter pins and how their size is
-TAPER PIN determined .
MOVABLE WASHER
MEMBER NOTE : Whenever uneven prong coţter pins
are used , the length measurement is to the end
THREADED TAPER PIN INSTALLED of the shortest prong .
FLATHEAD PIN С
-LENGTH
COTTER PIN
CC WASHER LDIAMETER
FLATHEAD PIN INSTALLED UNEVEN PRONGS OPTIONAL
©
AD.28
Figure 6-29 . - Types of cotter pins.
AM.330
Figure 6-28 . - Types of aircraft pins. SAFETY WIRE
Safety wire comes in many types and sizes.

continuously . The flathead pin should be One must first select the correct type and size of
secured with a cotter pin . The pin is normally wire for the job. Annealed corrosion -resisting
installed with the head up ( fig. 6-28 (C)). This wire is used in high -temperature, electrical
precaution is taken to maintain the flathead pin equipment , and aircraft-instrument applications.
in the installed position in case of cotter pin All nuts except the self-locking types must be
failure . safetied ; the method used depending upon the
141
Annealed copper safety wire is used for

sealing first aid kits, portable fire extinguishers,
oxygen regulator emergency valves, and other
valves and levers used for emergency operation
BOLT HEADS
of aircraft equipment. This wire can be broken
by hand in case of an emergency .
AUS
CONNECTORS AND COUPLINGS
A variety of clamping devices are utilized in

connecting ducting sections to each other or to
CASTLE NUT various components. Whenever lines, com
ponents, or ducting are disconnected or removed
for any reason , install suitable plugs , caps , or
coverings on the openings to prevent the entry
SAFETY METHODS SHOWN ARE FOR
of foreign materials. Tag the various parts to
RIGHT HAND THREADS . LEFT HAND OPPOSITE . insure correct reinstallation . Care should be
exercised during handling and installation to
insure that flanges are not scratched , distorted,
or deformed . Flange surfaces should be free of
dirt, grease, and corrosion . The protective flange
caps should be left on the ends of the ducting
until the installation progresses to the point
where removal is necessary to continue with the
SAFETY WIRE OVER HEAD installation .
In most cases it is mandatory to discard and
replace seals and gaskets . Insure that seals and
gaskets are properly seated and that mating and
alignment of flanges are fitted so that excessive
SAFETY WIRE AROUND HEAD
torque is not required to close the joint and
impose structural loads on the clamping device.
Adjacent support clamps and brackets should
remain loose until installation of the coupling
AM.331 has been completed .
Figure 6-30 . - Safety wire installation.
particular installation. Figure 6-30 illustrates the

FLEXIBLE CONNECTORS/ COUPLINGS
correct methods of installing safety wire. The Some of the most commonly used plain band
following general rules apply to safety wiring : couplings are illustrated in figure 6-31. When
installing a hose between two duct sections, as
1. All safety wires must be tight after installa illustrated in figure 6-31 , the gap between the
tion , but not under so much tension that normal duct ends should be 1/8 inch minimum to 3/4
handling or vibration will break the wire. inch maximum . When installing the clamps on
2. The wire must be applied so that all pull the connection, the clamp should be 1/4 inch
exerted by the wire tends to tighten the nut . minimum from the end of the connector.
3. Twists should be tight and even and the Misalignment between the ducting ends should
wire between nuts as taut as possible without not exceed 1/8 inch maximum .
overtwisting. Wire between nuts should be Marman type clamps commonly used in
twisted with the hands. The use of pliers will ducting systems should be tightened to the
damage the wire. Pliers may be used only for torque value indicated on the coupling. Tighten
final end twist prior to cutting off excess wire. all couplings in the manner and to the torque
142
(
MARMAN BAND CLAMP
E
MARMAN BAND CLAMPS TO

BE USED IN TIGHT AREAS
AN737 BAND CLAMP FOR

AN737 BAND CLAMP STANDARD INSTALLATIONS
1 / 8 - INCH MAXIMUM MISALIGNMENT
1/8 INCH MINIMUM

3/4 INCH MAXIMUM
1/4 INCH MINIMUM

AM . 1135
Figure 6-31. - Flexible line connectors.
value as specified on the clamp or in the 1. Fold back half of the sleeve seal and slip it
applicable Maintenance Instructions Manual . onto the sleeve .
2. Slide the sleeve (with the sleeve seal
When installing flexible couplings, such as the partially installed ) onto the line .
one illustrated in figure 6-32, the following steps 3. Position the split sleeves over the line
are recommended to assure proper security : beads.
143
When installing rigid couplings, follow the

SPLIT SLEEVE
steps listed below and illustrated in figure 6-33 .
COUPLING SLEEVE SLEEVE
SEAL
1. Slip the V -band coupling over the flanged
tube.
2. Place a gasket into one flange. One quick
rotary motion assures positive seating of the
gasket .
3. Hold the gasket in place with one hand
LINE BEADS while the mating flanged tube is assembled into
the gasket with a series of vertical and horizontal
motions to assure the seating of the mating
flange to the gasket .
NOTE : View B of figure 6-33 illustrates the
proper fitting and connecting of a rigid coupling,
SPLIT utilizing a metal gasket between the ducting
SLEEVE flanges.
SLEEVE SEAL
SLEEVE FOLDED BACK
4. While holding the joint firmly with one
hand , install the V -band coupling over the two
flanges.
5. Press the coupling tightly around the
flanges with one hand while engaging the latch.
AM.91 6. Tighten the coupling firmly with a ratchet
Figure 6-32 . - Installation of flexible line couplings. wrench . Tap the outer periphery of the coupling
with a plastic mallet to assure proper alignment
4. Slide the sleeve over the split sleeves and of the flanges in the coupling. This will seat the
fold over the sleeve seal so that it covers the sealing edges of the flanges in the gasket.
entire sleeve . Tighten again , making sure the recommended
torque is not exceeded .
5. Install the coupling over the sleeve seal and 7. Check the torque of the coupling with a
torque to correct value. torque wrench and tighten until the specified
torque is obtained .
NOTE : Torque values for the various sizes 8. Safety wire the V-band coupling as il
and types of couplings may be found by lustrated in figure 6-34 as an extra measure of
referring to the applicable Maintenance Instruc security in the event of T-bolt failure. If the nut
tions Manual. Some couplings will have the on the T-bolt is drilled for safetying, extend the
correct torque value marked on the outside of safety wire to the nut so that it will pull on the
the band . nut in a clockwise ( tightening ) direction . Most
V-band connectors will utilize a T -bolt with
some type of self-locking nut .
RIGID COUPLINGS MECHANICAL CONTROLS

The rigid line coupling illustrated in figure Included among the responsibilities of the
6-33 is referred to as a V-band coupling . When AMS are various mechanical control systems. A
installing this coupling in restricted areas , some mechanical control system may be either a cable
of the stiffness of the coupling can be overcome type system , push -pull rod system , or a
by tightening the coupling over a spare set of combination of both . Push-pull rod systems are
flanges and gasket to the recommended torque sometimes called " rigid " control systems, but
value of the joint . Tap the coupling a few times this is not to imply that cable type systems are
with a plastic mallet before removing it. to be called " flexible" control systems.
144
GN
E
(1 ) (2)
19 (3)
SA
, JD (4 )
249
56
(5) ( 6)
(A )
LATCH •
GASKET FLANGE
HIGH - STRENGTH " T " BOLT
END VIEW
COUPLING
CO O L NUT
FLANGE . -COPPER GASKET FLANGE
( B)
AM1136
Figure 6-33. - Installation of rigid line couplings.
145
present in system controls and no lost motion

LOCKWIRE WITH exists between the actuating device and the unit.
MS20995 - NC40 Consequently , cable-controlled units respond
2 STRANDS
MIN 3 TURNS quickly and accurately to cockpit control move
IN THIS AREA ment. In some simple cable systems, only one
cable is used and a spring provides the return
action .
Control Cables
V BAND COUPLER
O AM.1137
Figure 6-34 . - Safetying a V -band coupling.
CABLE CONTROL SYSTEMS

A cable is a group of wires or a group of
strands of wires twisted together into a strong
wire rope. The wires or strands may be twisted
in various ways. The relationship of the direc
tion of twist of each strand to each other and to
the cable as a whole is called the lay . The lay of
the cable is an important factor in its strength ,
for if the strands are twisted in a direction
opposite to the twist of the strands around the
center strand or core , the cable will not stretch
(or set ) as much as one in which they are all
twisted in the same direction . This direction of
twist (in opposite direction) is most commonly
adopted . Therefore, it is called regular or
ordinary lay. Cables may have right regular lay
or a left regular lay . If the strands are twisted in
the direction of twist around the center strand
Cables have many advantages. They will not or core , the lay is called a lang lay . There is a
sever readily under sudden strains such as occur right and left lang lay . The only other twist
during towing, as of aircraft, trucks , and the arrangement, that is, twisting the strands
like. Cables are stronger than steel rods or tubing alternately right and left , then twisting them all
of the same size . They flex without setting either to the right or to the left about the core is
(permanent deformation ) and can be led easily called a reverse lay. Most aircraft cable has a
around obstacles by use of pulleys . Cables can right regular lay.
be installed over long distances (such as in large When aircraft cables are manufactured, each
aircraft) without a great degree of sagging (or strand is first formed to the spiral or helical
bending), and vibration will not cause them to shape to fit the position it is to occupy in the
harden, crystallize, and break, as may be the finished cable . The process of such forming is
case with push-pull control rods . Because of the called preforming, and cables made by such a
great number of wires used in cables , cable process are said to be preformed. The process of
failure is never abrupt , but is progressive over preforming is adopted to secure flexibility in the
periods of extended use . When used for the finished cable and to relieve bending and twist
manipulation of a unit in a control system , they ing stresses in the strands as they are woven into
are usually worked in pairs - one cable to move the cable . It also keeps the strands from spread
the unit in one direction , the other to move it in ing when the cable is cut . All aircraft cable is
the opposite direction . Yet, in spite of the internally lubricated during construction .
second cable , weight is saved , because a push Aircraft control cables are fabricated either
pull rod needed to cause a similar movement in a from flexible , preformed , carbon -steel wire , or
unit would have to be quite thick and heavy from flexible, preformed, corrosion -resistant
(comparatively speaking). Since cables are used steel wire . The smaller corrosion -resistant steel
in pairs and are stretched taut, very little play is cables are made of steel containing not less than
146
17 percent chromium and 8 percent nickel while Cable Fittings

the larger ones ( those of the 5/ 16-, 3/ 8-, and
7/ 16-inch diameters) are made of steel which , in Cable ends may be equipped with several
addition to the amounts of chromium and nickel different types of fittings such as terminals ,
just mentioned , also contain not less than 1.75 thimbles, bushings and shackles . Terminal fit
percent molybdenum . tings are generally of the swaged type . (NOTE :
The swaging process is described in detail in
Cables may be designated 7 x 7,7 x 19 , or 6 x chapter 8. ) Terminal fittings are available with
19 according to their construction . A 7 x 7 cable threaded ends , fork ends, eye ends, single-shank
consists of six strands of seven wires each , laid ball, and double - shank ball end .
around a center strand of seven wires. A 7 x 19 Threaded ends, fork ends , and eye end
cable consists of six strands of 19 wires, laid terminals are used to connect the cable to
around a 19-wire central strand . A 6 x 19 IWRC turnbuckles , bellcranks, and other linkage in the
cable consists of six strands of 19 wires each , system . The ball type terminals are used for
laid around an independent wire rope center . attaching cable to quadrants and special con
nections where space is limited . The single -shank
The size of cable is given in terms of diameter ball end is usually used on the ends of cables and
measurement. If one speaks of a 1 / 8-inch cable the double -shank ball may be used at either the
or a 5 / 16-inch cable , he means that the cable ends or in the center of a cable run . Figure 6-36
measures 1/8 inch or 5/16 inch in diameter, illustrates the various types of terminal fittings.
measured as shown in figure 6-35 . Note that the Thimble , bushing, and shackle fittings may be
cable diameter is that of the smallest circle used in place of some types of terminal fittings
which would enclose the entire cross -section of when facilities and supplies are limited and
the cable . Aircraft control cables vary in immediate replacement of the cable is necessary .
diameters ranging from 1/16 inch to 3/8 inch . Figure 6-37 illustrates these fittings.
1
1 /8-5 / 32-7 / 32 DIAMETER 7X19
7 STRANDS - 19
DIAMETER WIRES TO EACH
STRAND
1/ 16- 3/32 DIAMETER 7X7
DIAMETER 7 STRANDS -7
WIRES TO EACH
AM.332
Figure 6-35 . - Cable cross sections.
147
Turnbuckles minor adjustments in cable length and for

adjusting cable tension . One of the terminals has
A turnbuckle is a mechanical screw device right-hand threads and the other has left-hand
consisting of two threaded terminals and a threads. The barrel has matching right -and left
threaded barrel. Figure 6-38 illustrates a typical hand threads internally. The end of the barrel
turnbuckle assembly . Turnbuckles are fitted in with left-hand threads inside can usually be
the cable assembly for the purpose of making identified by either a groove or knurl around
DOUBLE SHANK BALL END TERMINAL
SINGLE SHANK BALL END TERMINAL
WIRE CABLE THIMBLE
ROD END TERMINAL
THREADED CABLE TERMINAL
CABLE BUSHING
FORK END CABLE TERMINAL
CABLE SHACKLE
EYE END CABLE TERMINAL
AM.334
AM.333 Figure 6-37 . - Thimble, bushing, and shackle type
Figure 6-36 . - Types of terminal fittings. fittings.
148
SWAGING TERMINAL GROOVE BARREL PIN EYE
AM.335
Figure 6-38 . - Typical turnbuckle assembly.
After a turnbuckle is properly adjusted , it

must be safetied . There are several methods of
safetying turnbuckles. However, only two
methods have been adopted as standard proce
dures by the services. These methods are il
lustrated in figure 6-40 . The preferred method is
THREE THREADS the clip-locking method shown in (A). The
OUT
( MAX . ) wire-wrapping method shown in (B) is obsolete
TURNBUCKLE
BARREL
and should be employed only where facilities
FOUR THREADS will not permit the use of the clip locking
IN method .
Adjustable Connector Links
An adjustable connector link consists of two

or three metal strips with holes so arranged that
TOTAL TOLERANCE 7 THREADS EACH they may be matched and secured with a clevis
bolt to adjust the length of the connector. They
are installed in cable assemblies for the purpose
of making major adjustments in cable length and
to compensate for cable stretch. Adjustable
AM.336 connector links are used most often in very long
Figure 6-39. - Turnbuckle thread tolerance. cable assemblies .
that end of the barrel . Barrels and terminals are

available in both long and short lengths . Quick Disconnects
When installing a turnbuckle in a control
system , it is necessary to screw both of the
> Quick disconnects are used in cable systems
terminals an equal number of turns into the that may require frequent disconnecting. One
turnbuckle barrel. It is also essential that all type of quick disconnect is made with steel balls
turnbuckle terminals be screwed into the barrel swaged to the ends of the cable and which are
at least until not more than three threads are slipped into a slotted bar and secured with
exposed. On initial installation , the turnbuckle spring -loaded sleeves on each end of the bar.
terminals should not be screwed inside the Figure 6-41 illustrates the procedure for discon
turnbuckle barrel more than four threads. Figure necting and connecting this type of quick
6-39 illustrates turnbuckle thread tolerances . disconnect fitting.
149
STRAIGHT END
HOOK SHOULDER
LOOP END
HOOK LIP
-HOOK LOOP
-HOOK END
LOCK CLIP
DIRECTION OF PULL FOR INSPECTION
(A)
TURNBUCKLE FORK TURNBUCKLE
LOCK WIRE 4 TURNS WRAP CABLE
BARREL
2 TURNBUCKLE
::
4 TURNS WRAP TKIMBLE

EYE ANI 70
LOCK WIRE 4 TURNS WRAP
1 anco
SWAGED TERMINAL
( B)
AM.337
Figure 6-40 . - Safetying turnbuckles. (A ) Preferred method ; (B ) wire-wrapping method.
Cables Guides FAIRLEADS . - Fairleads may be made of a

solid piece of material to completely encircle
Fairleads, rubstrips, grommets, pressure seals, cables when they pass through holes in bulk
and pulleys are all types of cable guides. They heads or other metal parts (See fig. 6-42 .) This
are used to protect control cables by preventing type also may be used to reduce cable whipping
the cables from rubbing against nearby metal and vibration in long runs of cable. In the same
parts. They are also used as supports to reduce figure is a rubstrip , which protects cable along
cable vibration in long stretches (runs) of cable. one side from rubbing against metal edges.
Figure 6-42 shows some typical cable guides. Split fairleads are made for easy installation
150
NOTE HOW FITTING FITS

APPLY PRESSURE IN CLIP - IN LINE WITH
OUTER RECESS.
3/16 CABLE OUTER RECESS
1 DISCONNECTED POSITION
(FULL TENSION )
DISCONNECTING
PROCEDURE
EZ -RELEASED POSITION
CABLES DISCONNECTED
2 (TENSION BROKEN )
CABLE END FITTING
SPRING SLEEVE FITTING
CABLE END FITTING

CABLES DISCONNECTED
3 (TO BE JOINED)
APPLY PRESSURE
INNER RECESS
CONNECTING
PROCEDURE
SET AS SHOWN
4 CONNECTING POSITION
CABLES CONNECTED
5 (FULL TENSION)
AM.338
Figure 6-41. - Quick - disconnect procedure.
151
.
.
RUBSTRIP .
.
.
.
.
.
ODS
.
.
.
.
SPLIT
FAIRLEAD
SOLID FAIRLEAD ROUTE THE CABLE THROUGH THE

BULKHEAD AND SPRING CLIP WITH
THE CONCAVE SIDE OF THE CLIP
TOWARD THE BULKHEAD .
А B
RESTRAINING
RINGS -CONTROL
CABLE
RETAINING
UR
" GROOVE
SS
PUREN
D ED
ZE IZ
RI
SU
ES
GROMMET PR
AIR SEAL BULKHEAD
с D
AM.339
Figure 6-42 -Typical cable guides.
around single cables to protect them from to move with a minimum of friction . Most
rubbing on the edges of holes. pulleys used on aircraft are made from layers of
GROMMETS . - Grommets are made of rubber cloth impregnated with phenolic resin and fused
for use on small openings where single cables together under elevated temperatures and
pass through the walls of unpressurized compart pressures. Aircraft pulleys are extremely strong
ments . and durable and cause a minimum of wear on
PRESSURE SEALS . - Pressure seals are used
! the cable passing over them . Pulleys are provided
on cables or rods which must move through with grease -sealed bearings and usually do not
pressurized bulkheads. They fit tightly enough require further lubrication . However, pulley
to prevent air pressure loss but not so tightly as bearings may be pressed out, cleaned , and
to hinder movement of the unit . relubricated with special equipment . This is
usually accomplished only by Depot level main
Pulleys tenance activities .
Pulley brackets ( fig. 6-43 ), made of sheet or
Pulleys (or sheaves) are grooved wheels used cast aluminum , are required with each pulley
to change cable direction and to allow the cable installed in the aircraft. In addition to holding
· 152
o PULLEY
FAIRLEAD
BRACKET INSTALLATION
CABLE CABLE
ATTACHMENT TATTACHMENT
POINT POINT
PUSH-PULL TUBE
000
PIVOT PIVOT
POINT POINT
TYPICAL BELLCRANK TYPICAL WALKING BEAM
TYPICAL TYPICAL
SECTOR QUADRANT
AM.340
Figure 6-43 . - Control system components .
the pulley in the correct position and at the Sectors and Quadrants
correct angle, the brakets provide a guard to
prevent the cable from slipping out of the These units are generally constructed in the
groove on the pulley wheel. form of an arc or in a complete circular form .
153
They are grooved around the outer circum structure do not permit a straight run . They are
ference to receive the cable , as shown in figure often used in push -pull tube systems to decrease
6-43. The names sector and quadrant are used the length of the individual tubes and thus add
interchangeably . Sectors and quadrants are rigidity to the system.
similar to bellcranks and walking beams which A bellcrank has two arms which form an angle
are used for the same purpose in rigid control of less than 180 degrees, with a pivot point
systems. where the two arms meet . The walking beam is a
straight beam with a pivot point in the center.
Examples of a bellcrank and a walking beam are
RIGID CONTROL SYSTEMS also shown in figure 6-43. The two are so similar
in construction and use that the names bellcrank
Rigid control systems transfer useful move and walking beam are often used inter
ment through a system of push-pull rods, bell changeably .
cranks, walking beams, idler arms , and bungees. Bellcranks and walking beams are mounted in
The simplest rigid control system may consist of the structure in much the same way as pulley
push-pull rods and bellcranks only . assemblies . Brackets or the structure itself may
be used as the point of attachment for the shaft
Push - Pull Rods or bolt on which the unit is mounted .
Push-pull rods are rigid rods equipped with Idler Arms

eye fittings at each end or with aa clevis fitting at
one end and an eye fitting at the other. The eyes Idler arms are levers with one end attached to
contain a pressed -in bearing . The rods are the aircraft structure so it will pivot , and the
generally hollow, and they neck down to a other end is attached to the push-pull tubes.
smaller diameter at each end where the fittings Idler arms are used to support push-pull tubes
are attached . One or both of the fittings are and guide them through holes in structural
screwed into the necked portion of the rod and members .
are held in place by locknuts and are therefore
adjustable. When only one stem is adjustable the Bungee
stem of the other eye fitting is riveted into the
neck at its end of the rod . A hole is drilled into Bungees are tension devices used in some rigid
the threaded necks of the push-pull rods for systems that are subject to a degree of shock or
inspection to insure that the stem has engaged a overloading. They are similar to push -pull rods
safe number of threads. The stem must be visible and perform essentially the same function
through the hole. Push-pull rods are generally except that one of the fittings is spring loaded in
made in short lengths to prevent bending under one or both directions. That is , a load may press
compression loads and vibration . so hard in compression against the fittings that
the bungee spring will yield and take up the
Bellcranks and Walking Beams load, thus protecting the rest of the rigid system
against damage. The internal spring may also be
Bellcranks and walking beams are levers used mounted so as to resist tension rather than
in rigid control systems to gain mechanical compression. An internal double-spring arrange
advantage and to change the direction of motion ment will result in a bungee that protects against
in the system when parts of the airframe both overtension and overcompression .
154
CHAPTER 7
AIRCRAFT DAMAGE REPAIR
DAMAGE REPAIR PROCEDURES CLASSIFICATION OF DAMAGES
In the modern age of high -speed aircraft, the The Structural Repair Manual normally
AMS must be familiar with the principle of specifies the type of repair to be made to a
streamlining and fairing; also , the behavior of damaged structure . Damages can normally be
various metals in high -velocity air currents and classified under one of the following classifica
torsional stresses encountered during high -speed tions : negligible damage , damage repairable by
flying and maneuvering. One of the most impor patching, damage repairable by insertion, and
tant jobs the AMS will encounter is the repair of damage necessitating replacement. (See fig. 7-1 .)
damaged skin . All repairs must be of the highest The AMS must decide , after preinspection of the
quality and must conform to certain require damaged area , on one of the four classifications.
ments and specifications.
Methods of repairing the structure of a Negligible Damage
damaged aircraft are given in the Structural
Repair Manual for the specific aircraft . No one Negligible damage is damage or distortion that
set of repair rules will apply to all aircraft. The can be permitted to exist or can be corrected by
problem of repairing a damaged section is a simple procedure. Frequently , negligible
usually solved by duplicating the original part in damage can be repaired by stop drilling cracks ,
strength , using the materials and procedures removing dents , and fabricating temporary
specified in the aircraft Structural Repair fabric patches without placing any restrictions
Manual . on the aircraft.
PREINSPECTION OF DAMAGED AREAS Damage Repairable by Patching

When any part of the airframe has been Damage which exceeds negligible damage
damaged, the first step is to clean off all grease,, limits should be investigated to determine the
dirt, and paint in the vicinity of the damage so possibility of using a patch repair. A patch repair
that the extent of the damage may be deter is made by adding material around the damaged
mined. The adjacent structure must be inspected area to enable the damaged structure to carry its
to determine what secondary damage may have designed load .
resulted from the transmission of the load or
loads which caused initial damage .
the Damage Repairable by Insertion
Thoroughly inspect the adjacent structures for
dents, scratches, abrasions, punctures, cracks, This repair involves the removal of the
loose seams, and distortions. Check all bolted damaged portion of a member and replacing this
fittings which may have been damaged or portion with materials identical in shape and
loosened by the load which caused the damage strength to the damaged member . A backup
to the structure . plate (doubler) is used with this type of repair to
155
NEGLIGIBLE DAMAGE
DAMAGE REPAIRABLE BY PATCHING
DAMAGE REPAIRABLE BY INSERTION

‫ܘܘ‬
DAMAGE NECESSITATING REPLACEMENT
AM.341
Figure 7-1 . - Classification of damages.
156
Chapter 7 -AIRCRAFT DAMAGE REPAIR
reinforce the damaged area and provide aa surface from the illustration for the damaged com
to fasten the filler. This repair is used where a ponent.
flat surface is required. 4. From the component diagram , find the
index number /numbers for the damaged unit/
Damage Necessitating Replacement units.
5. The index number /numbers are then
Damage which cannot be repaired by any matched with the item number/numbers on the
practical means is classified as damage neces repair material chart . This chart will normally
sitating replacement . give the parts description, drawing number, gage,
type of material , and location of repair diagram .
6. The repair diagram is found by locating
SELECTION OF REPAIR MATERIAL the required section of the manual and turning
to the correct figure in that section . Access
The major requirement in making a repair is provisions and negligible damage information are
the duplication of strength of the original given on the repair diagrams. After the damage
structure . The Structural Repair Manual for the has been cleaned up , determine whether or not
aircraft concerned must be consulted for the the damage is negligible in accordance with the
alloy thickness, and temper designation of the
>
repair diagram . If the damage is within the limits
repair material to be used . This manual will also of negligible damage, it may be disregarded
designate the type and spacing of rivets or unless it is necessary to close the hole for
fasteners to be used in the repair. aerodynamic smoothness or sealing purposes. If
In some instances, substitution of materials the damage exceeds the limits of negligible
are allowed. For example, the P - 3 Structural damage, it must be repaired in accordance with
Repair Manual specifies that 2024 - T42 clad the repair diagram or replaced .
material may be substituted for 2024-T3 clad
materials in fuselage areas having sharp or
double curvatures. When making a substitution LAYOUT FOR REPAIR
of materials, and conflicting information be
tween manuals exists, the Structural Repair All repairs must be laid out to the given
Manual for the aircraft being repaired should be dimensions or by using the damaged part as a
used . pattern . Care should be exercised to avoid
When using the Structural Repair Manual, the scratching the repair material , except where
AMS normally has several steps . to take in cutting the material is desired . Scratches may
finding the correct repair materials and proce develop into cracks and cracks into structural
dures. Figure 7-2 illustrates each of the steps, failures. All marks on repair materials, other
and are listed in the procedures to follow . than cut lines, should be made with a pencil.
NOTE : The P-3 Structural Repair Manual was
selected as a typical manual. The procedures
that follow are typical , but are not standard.
Various manufacturers use different methods to SKIN REPAIRS
indicate the types of materials used and special
instructions for using their particular manual. Skin repair patches may be divided into two
1. The extent of the damage to the aircraft is general types , the LAP PATCH and the FLUSH
determined by the preinspection of the damaged PATCH . A brief description of both types of
area as previously explained . patches follows .
2. Using a master index diagram , identify the A lap patch is an external patch that has the
damaged group of the aircraft. From the table edges of the patch and the skin overlapping each
shown on the diagram , determine the section of other. The overlapping portion of the patch is
the manual where the component is found . riveted to the skin. On some aircraft, lap patches
3. After locating the correct group master are permitted in certain areas , but only where
index diagram , obtain the correct item number aerodynamic smoothness is not important.
157
ta
IM
19
To
0
4
1 FROM COMPONENT MASTER INDEX , LOCATE
DETERMINE EXTENT OF DAMAGE STRUCTURE ILLUSTRATION
DO NOT USE DRAWING NUMBERS -NUMBER FOLLOWING VIRGULE

FOR ORDERING PARTS - INDICATES OPPOSITE HAND
REFER TO NAVWEPS 01-75PAA - 4 PART
TCS
.
2
‫ܢܢ‬
IJU
m
In
Dcu
yºu
ooo
2 ONO -2.1.11
FROM MASTER INDEX DIAGRAM, LOCATE FROM KEY TO STRUCTURE ILLUSTRATION ,

APPLICABLE GROUP MASTER INDEX 5 LOCATE REPAIR ILLUSTRATION
CITKA OLLA
.
• .. CLA
NIMIA ALU SS
• OAM I l
Te vis
.
.
H- ( ) 190
ри
ха
DE
the NE
n
TA
IL
Amo .. Wa
.
' y
NOTE
L .
C
I C
. .
AZ
3 6
COMPARE CLEANED - UP DAMAGE WITH THE LIMITS OF NEGLIGIBLE
FROM GROUP MASTER INDEX DAMAGE , IF DAMAGE EXCEEDS THESE LIMITS, REPAIR THE PART
10.3.3
LOCATE COMPONENT MASTER INDEX IN ACCORDANCE WITH INSTRUCTIONS OR REPLACE PART,R14001.17
HC07187
AM.342
Figure 7-2.-How to use a Structural Repair Manual.
158
Chapter 7 - AIRCRAFT DAMAGE REPAIR
A flush patch consists of a filler patch which skin . This type of skin usually has a low margin
is flush with the skin when inserted. It is backed of safety .
up and riveted to a reinforcement plate which,
in turn , is riveted to the inside of the skin . This Lap Patches
reinforcement plate is usually referred to , on
some repair diagrams, as the doubler, or backup Lap patches may be installed in areas where
plate. On some high performance aircraft , only aerodynamic smoothness is not important. In
the flush patch is permitted in making skin areas where it is permitted , the lap patch may be
>
repairs. used in repairing cracks as well as small holes.

In repairing cracks, always drill a small hole ,
(normally called stop drilling), in each end of
OPEN AND CLOSED SKIN AREAS the crack before applying the patch . This is
normally done by using a No. 30 or 40 drill bit.
One of the factors which determine the exact This prevents the concentration of stresses at the
procedure to be used in making skin repairs is apex of the crack and distributes the stresses
the accessibility to the damaged area . Much of around the circumference of the hole . The patch
the skin on an aircraft is inaccessible from the must be large enough to install the required
inside for making repairs. The skin in such areas number of rivets as determined from the rivet
is referred to as CLOSED SKIN . Skin that is schedule indicated for the gage material in the
accessible from both sides is called OPEN SKIN . area which is damaged . ( See fig. 7-3 .) The
Repairs to open skin may usually be made in recommended patch may be cut circular, square,
the conventional manner, using specified types rectangular , or diamond shaped . The edges are
of standard rivets, but in repairing closed skin , normally chamfered (beveled ) to an angle of 45
some type of special blind fasteners must be degrees, for approximately one-half its thick
used. The exact type of fastener used will ness .
depend upon the type of repair made and the
recommendations of the aircraft manufacturer.
.
Another of the important factors to be
considered when making a skin repair is the
☺
stress intensity of the damaged panel . For

example, certain skin areas are classified as
highly critical, other areas as semicritical , while
still other areas may be classified as noncritical.
Repairs to damages in highly critical areas must
provide 100 percent strength replacement ;;
semicritical areas require 80 percent strength
replacement ; and noncritical areas require 60
percent strength replacement . When a repair
specifies it must provide 60 percent strength
replacement , this indicates the amount of repair
strength necessary to maintain a margin of
safety in skin areas . The 60 percent stress AM.343
intensity repair is specified when production Figure 7-3. - Lap patch for repairing a crack in
methods and stiffening requirements have stressed skin.
resulted in an overstrength skin with a high

margin of safety. This repair provides strength
and stiffness equivalent to specific design The rivet pattern is laid out on the patch ,
requirements rather than the original structure using the proper edge distance and spacing. The
of the material. The 100 percent stress intensity installation position of each rivet is marked with
repair makes the strength of the repaired skin a center punch. The impression in the material
equal to , or greater than , the original undamaged made with the center punch helps to keep the
159
damaged area is removed by cutting and

trimming the hole to a circular, square,
rectangular, or diamond shape . The corners of
the hole should be rounded to a minimum of
1 /4 -inch radius. The lap patch is fabricated and
installed in the same manner as previously
explained for repairing cracks.
Flush Patches
SURROUNDING
MATERIAL DENTED
‫נה‬DRILL Flush patches should be used where aero
F ‫ מנמו‬SLIPS OUT
‫גימנ‬ dynamic smoothness is required. The type of
‫ר‬
TOO DEEP flush patch used depends on the location of the
damaged area . One type is clear of internal
structures, and the other it is not . Like all types
CORRECT DEPTH TOO SHALLOW of repairs, the AMS must consult the applicable
Structural Repair Manual for the necessary
repair information . The repairs discussed next
are typical of most repairs .
AM.344 FLUSH PATCH CLEAR OF INTERNAL
Figure 7-4 . - Drilling holes for rivets. STRUCTURES . -In areas which are clear of
internal structure, the repair is relatively simple
drill from slipping away from the hole being to make . This is especially true where there is an
drilled. (See fig. 7-4 ). Drill only a minimum access door or plate through which the rivets can
number of rivet holes in the patch, normally be bucked. In inaccessible areas, the flush patch
four will suffice at an angle of 90 degrees to may be made by substituting blind rivets for
each other . Position the patch over the surface standard rivets, where permissible, and devising a
being repaired, insuring that the correct edge means of inserting the doubler through the
distances are being maintained . Drill four holes opening.
in the surface being repaired , using the predrilled One method is shown in figure 7-5 , in which
>
holes in the patch as a pattern for alignment. As the doubler has been split. To insert the doubler,
each hole is drilled , using the proper temporary slip the split edge under the skin and twist the
fasteners, secure the patch in place . When the doubler until it slides in place under the skin .
patch is temporarily secured , drill the remaining The screw in the center of the doubler is
rivet holes through the patch and surface being temporarily installed to serve as a " handle" for
repaired . Remove the patch and deburr all rivet inserting the doubler through the hole. This type
holes, using a deburring tool or a large drill bit . of patch is normally recommended for holes up
Prime the repair materials with the proper to 1 1/2 inches in diameter. It is generally more
corrosion preventive material prior to the satisfactory to trim a hole larger than 1 1/2
riveting operation. Secure the patch in position , inches to a rectangular or elliptical shape ,
using temporary fasteners, to maintain align rounding all corners to a generous radius. (See
ment during riveting. Riveting procedures are fig . 7-6. )
covered later in this chapter. On larger repair areas it is usually possible to
Holes may be repaired in either stressed or buck the doubler rivets by inserting and holding
nonstressed skin which are less than 3/16 inch in the bucking bar through the center of the
diameter by filling with a rivet. Drill the hole doubler. The filler is then riveted in place using
and install the proper size rivet to fill the hole. blind fasteners, if in a closed skin area . When
For holes 3/16 inch and larger, the AMS should blind rivets are used as substitutes for solid
consult the applicable Structural Repair Manual rivets, the Structural Repair Manual normally
for the necessary repair information . The specifies the next larger size. The proper edge
160
ASSUMED
DAMAGE ( 1)
(1 )
ASSUMED
DAMAGE ( 3)
( 3)
(2 )
( 2)
(4 )
-( 5)
(5 )
(6 )
(6 )
Oy
ASSEMBLED
REPAIR
ASSEMBLED
REPAIR
AM.345
AM.346
( 1 ) Assumed damage. ( 2) Damage cut out to a smooth ( 1 ) Ass ned damage. ( 2) Damage cut out to smooth
round hole. (3) Doubler split for insertion through cut rectangular shape. ( 3) Doubler. (4) Filler. (5 ) Doubler
out. (4) Filler. (5) Doubler riveted in place. (6 ) Filler riveted in place. (6) Filler riveted in place.
riveted in place.
Figure 7-6 . - Flush rectangular patch .
Figure 7-5. -Repair of small holes in skin with a
flush patch .
161
distances for the substitute fasteners must be

maintained .
ASSUMED DAMAGE
NOTE : Edge distance is discussed later. In all (1)
flush patches , the filler should be of the same
gage and material as the original skin . The
doubler , generally , should be of the same mate
rial , one gage heavier than the skin . Structural
Repair Manuals will specify the allowable substi (3 )
tution of materials. This can be in the form of a
note on the repair diagram . For example , the
RA-3B Structural Repair Manual shows the (2 )
following information in the form of a note :
Curved sheet : When substituting 2024-T for
0.025 to 0.071 inch 7075 -T, the 2024-T should
be one gage heavier than called for in 7075-T; if
the gage of the 7075-T is 0.080 or 0.090 inch ( 5)
the 2024-T should be two gages heavier than the
7075 -T.
Flat sheet : Substitute one gage heavier
2024 - T for all 7075 - T skin gages.
(4)
When laying out the size of the doubler , the

length should exceed the width . This enables the
doubler to be slipped in through the skin , so it
can be positioned for installation . This
eliminates the splitting and manipulation of the
patch required in installing doublers of square
and round flush patch repairs.
The filler is fabricated slightly less than the
dimensions of the hole being repaired . General
ly , the maximum clearance between the skin and
the filler is 1/32 inch . The doubler is fabricated
larger than the hole being repaired to allow for
the specified number of rivets required to attach ( 6)
the doubler to the skin being repaired . The
doubler, filler, and attaching skin rivet pattern
may be laid out , drilled , and deburred in the
identical manner as described previously for a
lap patch . After the required corrosion
preventive materials have been applied, the ASSEMBLED
doubler is positioned in the structures interior REPAIR
and secured with temporary fasteners. Inspect
the rivet holes for proper alignment and rivet the
doubler in place , using solid rivets . The filler can
then be riveted in place using blind fasteners. AM.347
NOTE : If the flush repair is in an open skin ( 1 ) Assumed damage. (2) Damaged skin cut out to a
area , the filler may be riveted to the doubler smooth round hole and rib repaired. (3) Two half- round
prior to installing the doubler. doublers. (4) Doublers riveted in place. (5 ) Filler. (6)
FLUSH PATCH OVER INTERNAL Filler riveted in place.
STRUCTURES . – Fabricating a flush patch over
-
Figure 7-7. -Flush patch over internal structure .

162
internal structure may tend to become difficult. stressed cover plate . The cover plate is normally
In some instances, it may be done by simply fabricated from material identical to the skin . A
using a split doubler and a filler, as shown in single row of nut plates is riveted to the doubler,
figure 7-7 . Frequently a split doubler, filler and the doubler is then riveted to the interior
strips, and filler are used in the repair. The filler side of the skin with two rows of rivets,
strip is used as a spacer, if a structural com staggered as shown in figure 7-8 . The cover plate
ponent under the skin has been damaged . In all is attached to the doubler with machine screws.
cases, the existing structure rivet holes should be When an access door is permitted and installed
used when the rivet pattern is laid out . The flush over internal structure , screws should be
patch over internal structure is installed using installed through the cover plate into the
the same methods as described for a flush patch internal structural member wherever possible .
clear of internal structure , except for modifica
tion of the doubler . Skin Replacement
Flush Access Door Sometimes damage to the metal skin is so
extensive that an entire panel must be replaced .
A flush access door installation , as shown in Also , an excessive number of patches or minor
figure 7-8 , is sometimes permitted . It is installed repairs to a section or area may require the
to facilitate repair to the internal structure and replacement of the entire panel .
to repair damage to the skin in certain areas . The As in all other forms of repairs, the first step
flush access door consists of a doubler and a is to inspect the damaged area thoroughly to
C
C
IC
C
FLUSH ACCESS COVER PLATEX

Сno
g
co
C
O
GO
12R
TYPICAL
EXISTING SKIN
EXISTING RIB
DOUBLER
FLUSH ACCESS COVER PLATE -EXISTING SKIN
SCREW DOUBLER -EXISTING

RIB
-EXISTING RIB NUT PLATE
SECTION A - A
AM.348
Figure 7-8.- Flush access door installation .
163
determine the extent of the damage . Inspect the the old sheet as a guide . The two sheets are then
internal structure for damage or signs of strain . fastened together with sheet metal fasteners.
Such members, when bent , fractured , or The use of sheet metal screws is not recom
wrinkled, must be replaced or repaired. They mended since they injure the edges of the rivet
may be sheared considerably without visible holes. The drilling should proceed from the
external evidence of such a condition. Drill out center to the outside of the sheet, inserting sheet
rivets at various points in the damaged area and metal fasteners at frequent intervals.
examine them for signs of shear failure. If impossible to use the old sheet as a
During the inspection , note carefully all template , the holes in the new sheet should be
unusual riveting problems - conditions which drilled from the inside of the structure . Use the
render riveting difficult or which make replace holes in the reinforcing members as guides, and
ment impossible. Any fixtures which will hinder insert fasteners in the same manner as described
riveting and prevent the use of straight bucking above. This is called back -drilling. Before placing
bars will be apparent in a thorough inspection. the new sheet on the framework to drill the
There will also be places where flanges or holes , make certain that the reinforcing
reinforcing members, or the intersection of members are aligned and flush at the points at
stringers, longerons , formers, frames, or rings which they intersect , otherwise the holes in the
make the bucking of rivets very difficult. This new sheets will not be accurately aligned. For
problem can be solved by designing and making the same reason , the new sheet should have the
>
bucking bars to suit these particular situations. same contour as the old before drilling the rivet
Care must be taken to avoid mutilating the holes .
damaged skin in the process of removal . In most In duplicating holes from reinforcing
cases it can be used as a template for layout of members to skin , extreme care must be
and drilling holes in the new piece of skin. exercised or both frame and skin will be ruined .
The rivet holes in stringers, longerons, bulk Since most bulkheads, ribs , and stringers depend
heads , formers, frames, rings, and other internal on the skin for some of their rigidity, they can
members must be kept in as good condition as easily be forced out of alignment in the drilling
possible . If any of these members are loosened process. The skin must be held firmly against the
by the removal of rivets, their location should be framework , or the pressure from the drilling will
marked so that they can be returned to their force it away from the frame and cause the holes
original position as necessary , while the repair is to be out of alignment. This may be overcome
being made . by placing a block of wood against the skin and
Reference should be made to the applicable holding if firmly while the drilling progresses.
repair material chart in the aircraft Structural Also, make sure that the drill is held at a
Repair Manual for the gage and alloy of material 90 -degree angle to the skin at all times, or the
to be used for the replacement panel. The size holes will be elongated and out of alignment.
and shape of the panel may be determined in When drilling through anchor nuts a smaller
either of two ways . The dimensions can be pilot drill should be used first. Care must be
measured during the inspection , or the old skin used so as not to damage the anchor nut threads.
can be used as a template for the layout of the The pilot holes are then enlarged to the proper
sheet and the location of the holes, the latter size .
method being preferable and more accurate. It may be necessary to use an angle attach
Regardless of the procedure used, the new sheet ment or flexible shaft drill in places where it is
must be large enough to replace the damaged impossible to insert a straight drill. In case
area , and may be cut with an allowance of 1 to 2 neither type can be inserted , the new section can
inches of material outside the rivet holes. be marked carefully with a soft pencil through
If the old sheet is not too badly damaged, it the holes in the old section. Another method of
should be flattened out and used as a template. marking the location of the new holes is to use a
The new sheet , having been cut approximately 1 transfer or prick punch as shown in figure 7-9 .
inch larger than the old , should then be drilled Center the punch in the old hole, then tap the
near the center of the sheet, using the holes in punch lightly with a hammer. The result should
164
At the free end of the botton section of the

hole finder is a guide rivet which drops into the
old holes in the sheet still in place. The free end
TRANSFER of the top section of the hole finder has a hole
PUNCH in a position which exactly matches the position
of the guide rivet, and through this opening the
USE OLD SKIN AS
new hole is drilled . Thus, as the hole finder is
TEMPLATE moved along, the guide rivet drops into an old
hole and automatically determines the position
of the new hole .
TS WONOCIVEXY I
After all the holes have been drilled, the
TYTDANIA TENLOOPSY temporary fasteners are taken out and the sheet
is removed from the framework . The burrs left
NEW SKIN by drilling must be removed from both sides of
all holes in the skin , the stringers, and the rib
flanges. Burring may be accomplished with a few
AM.349 light turns of a deburring tool or drill bit . In this
Figure 7-9 . - Transferring rivet holes. way particles of metal left around the edges of
the drilled holes are eliminated . If they were not
removed , the joint would not be tight and rivets
might expand , or flash, between the parts being
riveted .
NEW REINFORCED PLASTIC AND

SKIN
SANDWICH CONSTRUCTION REPAIR
OLD
SKIN This section deals with the materials and
ANGLE
procedures to be used in repairing reinforced
NEW
plastic and sandwich construction components.
SKIN 10
SAN
The procedures discussed are general in nature.
When actually repairing reinforced plastic and/or
sandwich construction components, refer to the
applicable Structural Repair Manual .
REPAIR OF REINFORCED PLASTIC
The repair of any damaged component made

AM.350 of reinforced plastic requires the use of identical
Figure 7-10. -Using a hole finder. materials, whenever they are available , or of
>
approved substitutes for rebuilding the damaged

portion . Abrupt changes in cross -sectional areas
be a mark which will serve to locate the hole in must be avoided by tapering joints, by making
the new sheet. small patches round or oval instead of
Still another way to locate the rivet holes rectangular, and by rounding the corners of all
without a template is to use a hole finder, large repairs. Uniformity of thickness of core
similar to the one shown in figure 7-10. This and facings is exceedingly important in the
device makes it possible to drill holes in the new repair of radomes. Repairs of punctured facings
section of skin in perfect alignment with the and fractured cores, therefore, necessitate re
holes in the old section . The hole finder is made moval of all the damaged material, followed by
in two sections-an upper part and a lower part replacement with the same type of material and
which are fastened together at one end . in the same thickness as the original.
165
All repairs to components housing radar or DAMAGE TO FACING

radio gear must be made in accordance with the
manufacturer's recommendations. This informa
tion may be found in the aircraft Structural
Repair Manual or in drawings and specifications.
(A) FACING
Investigation of Damage
DAMAGED MATERIAL REMOVED BY SANDING
Before a thorough inspection of the damage
can be made , the area should be cleaned with a
cloth satu rated with methyl-ethyl-ketone
(MEK ). After drying, the paint should be re
(B )
moved by sanding lightly with No. 280 grit
sandpaper, then clean the sanded area with IMPREGNATED CLOTH
MEK. The extent of damage can then be
determined by tapping the suspected areas with
a blunt instrument . The damaged areas will have
a dull or dead sound , while the undamaged areas
will have a clear metallic sound.
Damages are divided into four general classes : (C)
surface damage , facing and core damage ,
puncture damage (both facings and core), and
damage requiring replacement .
Surface Damage REPLACED LAMINATIONS SANDED TO CONTOUR
( D)
The most common types of damage to the
surface are abrasions, scratches, scars, dents,
cuts, and pits. Minor' surface damages may be
repaired by applying one or more coats of
room -temperature catalyzed resin to the
AM.351
damaged area . More severe damages may be
Figure 7-11 .-Ply repair (scarfed method ).
repaired by filling with a paste made from
room -temperature resin and short glass fibers.
Over this coated surface, apply a sheet of figure 7-11 . This repair is made in the following
cellophane, extending 2 or 3 inches beyond the manner : Sand out the damaged laminate plies as
repaired area . After the cellophane is taped in shown in view ( B). The area should be sanded to
place , work out all the air bubbles and excessive a circular or oval shape , then the area should be
resin with the hand or a rubber squeegee . Allow tapered uniformly down to the deepest penetra
the resin to cure at room temperature , or if tion of the damage .
necessary , the cure can be hastened by the use
> The diameter of the scarfed ( tapered ) area
of infrared lamps or hot sandbags. After the should be at least 100 times the depth of the
resin has been cured, remove the cellophane and penetration . Care should be exercised when
sand off the excess resin ; then the entire using a mechanical sander. Excess pressure on
repaired area is lightly sanded preparatory to the sander can cause the sandpaper to grab ,
refinishing. resulting in the delamination of undamaged
PLY DAMAGE ( SANDWICH TYPE plies.
LAMINATES ).-
) When the damage has pene CAUTION : The sanding of glass cloth re
trated more than one ply of the cloth in the inforced laminates produces a fine dust that may
sandwich type laminates , the repair may be
> cause skin irritation . In addition , breathing of an
made using the scarfed method illustrated in excessive amount of this dust may be injurious;
166
therefore, precautions as to skin and respiration used , the dimensions should be maintained as
protection must be observed . illustrated .
Brush coat the sanded area with one coat of In areas that have become delaminated , or
room -temperature -setting resin and apply the contain voids or bubbles, clean the area with
contoured pieces of resin -impregnated cloth , as
> MEK and determine the extent of the delamina
shown in (C ) of figure 7-11 . Tape a sheet of tion , then drill holes at each end or on the
cellophane over the built-up repair and work out opposite sides of the void using a No. 55 drill
the excess resin and air bubbles . Cure the repair bit , extending through the delaminated plies.
in accordance with the resin manufacturer's Figure 7-13 illustrates the procedure for repair
instructions, then sand the surface down (if of delaminated plies.
necessary ) to the original surface of the facing. Additional holes may be needed if air entrap
PLY DAMAGE (SOLID LAMINATES ).- Ply ment occurs when injecting the resin . Using a
damage to solid laminates may be repaired using hypodermic needle or syringe, slowly inject the
the scarfed method described for sandwich type appropriate amount of resin until the void is
laminates, or the stepped method shown in filled and flows freely from the drilled holes.
figure 7-12 (A) may be used. After the voids are completely filled, bring the
When the wall is being prepared for the area down to proper thickness by working the
stepped repair, a cutting tool with a controlled excess resin out through the holes , then cure and
depth will facilitate the cutout and should be refinish .
used to avoid possible damage to the layers
underneath . If the layer of glass cloth under Facing and Core Damage
neath is scratched or cut, the strength of the
repair will be lessened. Care should be exercised HONEYCOMB CORE . - Damages extending
not to peel back or rupture the adhesion of the completely through one facing of the material
laminate layers beyond the cutout perimeter. and into the core require removal of the
Removal of the cutouts may be accomplished by . damaged core and replacement of the damaged
peeling from the center and working carefully to facings in such a manner that normal stresses can
the desired perimeter of the cutout . Scrape each be carried over the area . The scarfed method
step , wipe clean with cloths moistened with illustrated in figure 7-14 is the preferred method
MEK, and allow to dry thoroughly . Cut the for accomplishing small repairs of this type.
replacement glass fabric pieces to an exact fit Repairs of this type may be accomplished as
with the weave directions of the replacement follows:
plies running in the same direction as the Carefully trim out the damaged portion to a
existing plies . Failure to maintain the existing circular or oval shape and remove the core
weave direction will result in a repair that is completely to the opposite facing. Be careful
greatly under strength . Replace each piece of not to damage the opposite facing. The damaged
fabric, being careful to butt the existing layers facing around the trimmed hole is then scarfed
of fabric plies together, but do not overlap back carefully by sanding. The length of the
them . The laminate layers should be kept to the scarf should be at least 100 times the facing
proper matching thickness . thickness as shown in (B ) of figure 7-14. This
When the entire wall has been penetrated , as scarfing operation must be done vary accurately
shown in figure 7-12 (B) , one-half of the to a uniform taper .
damaged plies should be removed from one side Cut a piece of replacement core material (or a
and the replacement buildup completed , then suitable substitute ) to fit snugly in the trimmed
repeat removal and buildup procedure on the hole . It should be equal in thickness to the
opposite side . If the damage occurs over a original core material. Brush coat the repair area
relatively large or curved area, make up a plaster and the replacement honeycomb , exercising care
mold conforming to the contour and extending to prevent an excessive amount of resin from
1 inch past the damage , and insert it in the entering the honeycomb cells .
damaged area when repairing the first half of the Insert the honeycomb repair section and place
plies. When the stepped method of repair is the resin -impregnated cloth over the repair area
167
LAMINATED GLASS LAMINATED GLASS

FABRIC DAMAGED FABRIC BROKEN THRU
ONE SIDE ONLY
CROSS SECTION DAMAGE CROSS SECTION DAMAGE
А A B B
.50 50
.50
SECTION A-A 25 SECTION B- B
.50
REPAIR CUTS REPAIR CUTS
-REPAIR PLIES
REPAIR PLIES
WWW
REPAIR INSTALLED REPAIR INSTALLED
( A) (B)
AM.352
Figure 7-12.- Repair of solid laminates ( stepped method ) .
168
Hypodermic needle filled

with resin .
Laminated part
Void or delaminated
area .
Drill two holes at opposite ends

of damaged area to depth that
extends into void or delamination . Remove final - finish or rain - erosion
coating approximately 2 inches
beyond cutout in upper ply .
Plies of laminated part. Repair material :

Resin injected into
drilled hole .
SECTION A-A
AM.353
Figure 7-13. -Delaminated ply repair.
DAMAGE TO CORE DAMAGED FACING SCARFED

-100 T CORE FOR PATCH
REMOVED
(A) (B)
CORE REPLACED IMPREGNATED CLOTH
TUNUT
(C )
AM.354
Figure 7-14 . - Honeycomb type core repair.
169
as shown in (C) of figure 7-14 . Cover the repair LAMINATED GLASS FORMED IN PLACE FILLER
FABRIC SKIN BROKEN OR HONEYCOMB CORE
area with cellophane sheeting and cure the repair DAMAGED
in accordance with the resin manufacturer's
instructions.
After the repair has been cured , sand the
surface to its original contour. The entire area
should be lightly sanded before refinishing.
FOAM TYPE CORE. -The damaged core
should be removed by cutting perpendicular to
the surface of the face laminate opposite the
DAMAGE
damaged face. Scrape the inner facing surface
clean , making sure there is no oil or grease film
in the area , to insure good bondage of the foam
to the laminate . Fill the area where the core has
been removed with the filler material specified
in the aircraft Structural Repair Manual. Figure B B
7-15 illustrates the replacement of a foam type

core .
NOTE : Do not use MEK to clean the damage
as it may soften and weaken the foam .
Puncture Damage CUT AWAY DAMAGED CORE

AREA AND FILL WITH
SPECIFIED FILLER
HONEYCOMB CORE . - Repairs to damages
-
.50
completely through the sandwich structure may REMOVE LAYERS OF
LAMINATE AS SHOWN
be accomplished either by the scarfed method
(similar to the repair described for damage
extending into the core ) or the stepped method .
The scarfed method is normally used on small
punctures up to 3 or 4 inches in maximum
dimension and in facings made of thin cloths SECTION B-B
(which are difficult to peel), whereas the
stepped method is usually employed on larger REPAIR CUTS
repairs to facings composed of thick cloths. REPAIR MATERIAL
The scarfed method of repair for punctures is

the same as that used for damage extending into ..
.
the core , with the exception that the opposite

side of the sandwich is provided with a tem
porary mold or block to hold the core in place
during the first step. ( See (C ) fig. 7-16. )
After the first facing repair is cured complete
ly , the mold and the shim (temporarily replacing
REPAIR INSTALLED
the facing on the opposite side) are removed .
The repair is then completed by repeating the NOTE
procedure used in the first step. When this facing O REPLACE DAMAGED CORE MATERIAL
is cured , the surface should be sanded down to
>
WITH SPECIFIED FILLER
the original contour and the repair area lightly
sanded in preparation for refinishing. AM.355
When using the stepped method of repair, the Figure 7-15. -Foam type core repair.
damaged area is first trimmed out to a round or
170
-HOLE THROUGH RADOME HOLE THROUGH RADOME
(A )
(A )
HOLE TRIMMED, CORE REMOVED,
HOLE TRIMMED, CORE REMOVED, AND FACING
SCARFED
Himalt AND FACING " STEP - PEELED "
(B)
(B) IMPREGNATED CLOTH WITH
EXTRA THIN LAYER
IMPREGNATED CLOTH + 2
TEMPORARY BLOCK -TEMPORARY SHIM

OR MOLD
TEMPORARY BLOCK TEMPORARY SHIM
MOLD COMPLETE OPPOSITE FACING IN A SIMILAR
(C) OPERATION
(C )
AM.356
Figure 7-16 . - Scarfed repair method.
AM.357
Figure 7-17. -Stepped repair method.
oval shape, or to a rectangular or square shape
( preferable having rounded corners). manner as the outer facing. After the inner
The individual plies are then cut out as repair has been cured, the entire repair area
illustrated in figure 7-17 . Each ply is “ stepped ” should be sanded to the original contour and
back 1-1 /2 inches and trimmed out using a sharp prepared for refinishing.
knife. The sides of the repair should be parallel FOAM TYPE CORE . -When the puncture
with the weave of the cloth , if possible. penetrates the entire wall, remove the damaged
NOTE : Do not cut through more than one core and face laminates to one -fourth inch past
layer of cloth . If the layer of cloth underneath is the perimeter of the hole on the inner face.
scratched , the strength of the repair will suffer. Make a plaster support to replace the removed
The opposite facing is shimmed and backed core, conforming to the curvature of the inside
up with a mold and the core material is inserted layer of the inner face. Figure 7-18 illustrates a
as previously described . The outer repair plies punctured repair with a plaster support.
are soaked in the resin and laid over the After repair to the inner face has been
damaged area . An extra layer of thin cloth is laid completed, remove the plaster support and
over the repair area to extend one -half inch over continue the repair on the opposite side .
the undamaged facing. The repair area is then
covered with a sheet of cellophane to apply Finishing of Repaired Areas
pressure , and allowed to cure .
The inner facing is then replaced in the same In the repair of reinforced plastic parts, the
171
LAMINATED GLASS
FARK SKINS BROKEN
final step is to refinish the part with a finish
ON BOTH SIDES FORMED IN PLACE FILLER identical to the original, or an acceptable substi
OR HONEYCOMB COR
DAMAGED . tute. In refinishing radomes and other surfaces
which enclose electronic equipment , do not use
metallic pigmented paints or other electronic
reflective type materials because of undesirable
shielding and interference effects. Always use
the materials recommended in the applicable
Structural Repair Manual for refinishing both
the interior and exterior surfaces of reinforced
DAMAGE
plastic components .
PLASTER SUPPORT Reinforced plastic components whose frontal
areas are exposed to high speeds are frequently
coated with a rain erosion coating. Rain erosion
coatings protect the component against pits
which are caused by raindrops hitting the
component at high aircraft speeds. These pits or
.25
eroded areas can cause delamination of the
component glass cloths if allowed to progress
unchecked .
COAT THIS SURFACE OF SECTION A-A
SUPPORT WITH PARTING RAIN EROSION RESISTANT COATINGS.
AGENT
Rain erosion resistant coatings for reinforced
plastic components conform to Specification
MIL-C-7439 . Coatings conforming to this speci
А А fication are classified as follows:
Class I is aa rain erosion resistant coating which
is furnished in kit form . This kit consists of a
primer, accelerator, diluting solvent, and
neoprene .
Class II is a rain erosion resistant coating with
an additional surface treatment to minimize
PLASTER SUPPORT radio noise resulting from precipitation static on
PLASTER SUPPORT AND REPAIR CUTOUT the coated surface. This coating is also supplied
REPAIR MATERIAL in kit form and consists of a primer, accelerator,
diluting solvent , neoprene , and antistatic coat
ing .
These kits (MIL -C - 7439, Classes I and II) are
packaged unaccelerated to provide longer shelf
life. The neoprene is ready to use only after the
catalyst (accelerator) has been added . The
material in these kits should be mixed and
applied in accordance with the instruction sheet
REPAIR INSTALLED supplied by the kit manufacturer.
NOTE
Safety Precautions
D REPLACE DAMAGED CORE MATERIAL
WITH SPECIFIED FILLER
The following general safety precautions
should be observed when making repairs to
AM.358 reinforced plastic components. These safety
Figure 7-18. -Foam type puncture repair. precautions should be reviewed before at
tempting any repairs to reinforced plastics .
172
1. Local station safety regulations as to fire Delamination

and health hazards must be complied with .
2. All solvents are flammable, therefore, Facing-to -core voids of less than 2.5 inches in
observe proper handling procedures. diameter can usually be repaired by drilling a
3. Personnel involved in the mixing or han series of holes 0.06 to 0.10 inch in diameter in
dling of catalyzed resin prior to the curing the upper facing over the void area . An
operation should wear rubber gloves. After using expandable foaming resin , such as Thermofoam
rubber gloves , the hands should be cleaned with 607 , or equivalent, is then injected through the
soap and water and rinsed with vinegar to holes with a pressure type caulking gun .
neutralize any catalyst particles. When the void is on the lower surface of the
4. Never mix the catalyst and promoter panel, only sufficient resin must be injected as
together as they are explosively reactive as a to completely fill the void . With voids on the
mixture . Always mix the promoter with the upper surface, the core area should be filled
resin first and then add the catalyst to the until the resin comes out of the injection holes.
mixture . These holes should be sealed with a thermo
5. The toxicity of polyester formulation has setting epoxy resin adhesive , and the entire
not been definitely established . Some of the assembly cured with lamps, as required for the
components are known to cause nasal or skin adhesive system .
irritation to certain individuals . Adequate When the void areas are large, it is necessary
ventilation should be provided. to remove the facing over the damaged area and
6. The sanding operation on glass cloth re follow the repair procedures for a puncture. (See
inforced laminates gives off a fine dust that may fig. 7-19 . )
cause skin or respiratory irritations. Inhalation
of excessive amounts of this dust should be
avoided. Protection should be provided for Punctures
respiration and skin .
7. Do not store catalyzed resin in an air-tight A puncture is defined as a crack , break , or
container or an unvented refrigerator. hole through one or both skin facings with
resulting damage to the honeycomb and /or balsa
wood core . The size of the puncture , amount of
REPAIR OF SANDWICH CON damage to the core , assembly to be repaired
STRUCTION (HONEYCOMB (rubber, elevator, etc.), and previous repairs to
AND BALSA WOOD CORE ) the damaged assembly are factors to be con
sidered in determining the type of repair to be
The repairs discussed in this section are made. Damage to a honeycomb and/or balsa
applicable to structural type sandwich construc wood core assembly that exceeds a specified
tion consisting of aluminum alloy facings length or diameter in inches or the total number
bonded to aluminum honeycomb and balsa of repairs exceeds a specified percentage of the
wood cores . total bonded area necessitates replacement of
the assembly.
Minor Surface Damage NOTE : These figures are found in the ap
plicable Structural Repair Manual.
The most common types of damage to the HONEYCOMB CORE .-The repair shown in
surface are abrasions, scratches, scars , and minor figure 7-19 (A) is used when a puncture through
dents. These minor surface damages require no one skin facing has caused only minor damage to
repair other than the replacement of the original the core material. To repair this type damage
protective coating to prevent corrosion; proceed as follows: Cover the component with a
provided no breaks, holes, or cracks exist. The suitable protective covering (polyvinyl sheet or
procedures and materials used in replacing the kraft paper ). Cut out a section of the protective
original protective coating are outlined in covering that will extend approximately 2 inches
chapter 11 . beyond the damaged area . Use masking tape to
173
MASK AREA AROUND

DAMAGE APPROXIMATELY PATCH : SANE MATERIAL AS DAMAGED
TWO INCHES BEYOND FACING . PATCH MUST EXTEND AT LEAST

I INCH BEYOND STOP HOLES. PATCH
STOP HOLES .
ADHESIVE
FILL VOID WITH
SPECIFIED FILLER.
(
)
A
SECTION A - A
STOP DRILL
EXISTING STRUCTURE
REPAIR PARTS
CORE FILLER
FILLER
PATCH : I INCH BEYOND
THE HOLE ON ALL SIDES.
BEVEL EDGE9 450
‫ܣܝ‬
CORE REPLACEMENT FILLER
SKIN
SECTION B - B
(B)
PATCH
PATCH
SECTION C - C
MILES
-PATCH
( c)
AM.359
(A) Skin facing, minor damage to core ;

(B ) Skin facing, extensive damage to core ;
(C ) Skin facings and core damaged.
Figure 7-19 . - Sandwich construction puncture repair ( honeycomb core).
174
hold the cutout in place . Stop-drill as necessary

through the skin facing only.
( 1)
Strip the paint and protective coating 1 1/2
ASSUMED DAMAGE inches beyond the stop -drilled holes. The
When who n
o
stripped area is then cleaned with a special .
cleaning paste. Fill the void with the specified

filler material to within approximately 0.063
inch of the skin facing and cure as directed .
( 2) Prepare a round or oval patch large enough to
overlap the damaged area at least 1 inch. Apply
sealant to the undersurface of the patch and to
Z
GOATRIDIUILTHIVAIP ZA
WA
the filler and skin surface. Install the repair
patch, maintaining correct overlap, and clamp to
the assembly to assure contact with the skin
facing. Cure as directed. Remove the excess
adhesive and refinish as necessary .
AKITOACHIM LVU UN The repair shown in figure 7-19 (B) is used
( 4)
when a puncture through one skin facing has
caused extensive damage to the honeycomb
core . When the core has been damaged
extensively the damaged material must be re
placed .
ASSEN BLED REPAIR
(59
Prepare the assembly as previously described .
B
Cut out the damaged skin facing with a hole saw
or aviation snips. File the edges of the hole
smoothly . Using a pocket knife, carefully cut
out the damaged core. CAUTION : Do not
damage the opposite facing. Install a new core
LIMIT
filler and complete the repair as previously
described for view (A) of figure 7-19 .
The repair shown in figure 7-19 (C) is used
when both skin facings and the core have been
( 31 damaged . Use the same procedures as described
ATHOR above for view (A) and (B) to facilitate this
SECTION A-A
repair.
(54 BALSA WOOD CORE . - The repair shown in
figure 7-20 is used when no gain in structural
HTTP WHOUNT strength is desired and is only to be used for
sealing holes of 1 square inch or less in external
SECTION B - B
( 5% surfaces. The damaged area should be cut out to
a smooth circular or rectangular shape . A 3/8
inch minimum radius must be provided at the
corners of rectangular cutouts.
AM.360 NOTE : The afore -mentioned information
· ( 1 ) Assumed damage. (2) Damage cut out to a smooth applies to all repairs made to balsa wood core
rectangular hole. ( 3) Inner metal face cut back and panels. In cutting out the damaged area, care
beveled. (4) Filler plug. (5) Filler glued in place, sealed , must be taken not to separate the metal faces
and fabric patches applied. from the core . This can be accomplished by
using a very fine -toothed coping or hacksaw
Figure 7-20 . -Balsa wood repair with filler plug and blade for straight cuts, and cylindrical saws (hole
fabric patch . saws) for cutting holes or rounding corners.
175
After the damaged section has been cut out ASSUMED

DAMAGE
file the edges smooth using a fine cut file only.
Then inspect the area for separation of the skin
facing from the balsa wood core . If the facing u
has separated from the core, rebond the two W
WWUILTWunun
surfaces, using the procedures outlined in the

previous section on skin separation. Then ( 2) SHUH
complete the repair as shown in figure 7-20. -( 3 )
SECTION A -A
Figure 7-21 illustrates one flush type balsa
wood core repair that is used on puncture
damages larger than 1 inch . To facilitate this (4)
+
X
type repair, cut out the damaged area as
x
+
X
x
previously described. After the damaged area has
X
X
AT
been cut out , the inner metal face is cut back 1 AIDIA
x
inch and the core material is removed . (See (3 ) UUTONH A
MOHINH DOUAPUTHIN
4X
fig . 7-21 . ) 1
X
t
Inspect for adhesion of the face to the core
X
t
( 7)
+t
and seal the exposed filler material to prevent
XX
t
the entry of moisture . Lay out the required rivet
t
7 t
+
t
X
pattern and drill pilot holes in the panel . (See
t t
+
( 5)
t t
x
X
(4) fig. 7-21 .) NOTE : The rivet size , rivet
*
t
(6)
*
spacing, and number of rows of rivets are given
X
F
+
+
**
in the appropriate repair section of the ap
*
X
+
plicable Structural Repair Manual.
*
x X
)
Next , prepare two patch plates ; a wood ,
x
+
15)
plywood , or phenolic filler; and a metal filler.
оо
(See ( 5) fig. 7-21 . ) The outer patch plate should ( 8)
O
o
fill the hole in the core, and the inner patch
о
so
о
plate should overlap the hole in the core
0
0
approximately 1 inch for each row of rivets . о
о
Locate the patch plates and wood filler. Using n
Mario an
the pilot holes in the panel as a guide, drill pilot HAMAM withmicroem
holes through the patch plates and wood filler.
The patch plates and wood filler are then ASSEMBLED
bonded to the panel using the specified adhe REPAIR
sive. Next , locate the metal filler and drill pilot
holes through both patch plates and the wood
filler . ANTOT MODEL
All pilot holes are then size drilled , and
machine or press countersunk , as applicable. SECTION B - B
Complete the repair by installing the specified
rivets.
AM.361
When aerodynamic smoothness is not desired ,
a nonflush patch such as the one shown in figure ( 1 ) Assumed damage. (2) Damage cut out to a smooth
7-22 can be used . Notice that this type repair rectangle. (3) Inner metal face cut back and core
utilizes two patch plates , a wood filler, and removed. (4) Rivet pattern. ( 5) Patch plates. ( 6) Wood,
plywood , or phenolic filler. (7 ) Metal filler. (8 ) Flush
nonflush rivets. Otherwise, the procedures rivets installed .
described for the repair shown in figure 7-21 are
applicable to this type repair. Figure 7-21 . -Balsa wood repair with flush patch .
176
TRAILING EDGE REPAIR

n
a
r
a
t
(1)
i
V A trailing edge is the rearmost edge of an
NI
MA airfoil (wing, flap, rudder, elevator, etc.). It may
TA
UL >
WLO
WIO ASSUMED DAMAGE
be a formed or machined metal strip or possibly
a metal covered honeycomb or balsa wood core
material which forms the shape of the edge by
tying the ends of a rib section together and
joining the upper and lower skins. These trailing
..
edges are very easily damaged. The majority of

(6 ) this type damage can be avoided if care is taken
(5 ) when moving aircraft in confined spaces, and / or
V
when positioning ground support equipment

a
(6 ) (2 )
r
around parked aircraft.

s
t a
( 3)
t
X
NOTE : The trailing edges on some high
w
WD /
performance aircraft are almost knife edge in
construction . Extreme care must be taken when
72 working around these surfaces to avoid person
17: 47 ,
TUNEC nel injury .
ROVIHIN
MARATHO The following paragraphs briefly describe the
procedures to be used in repairing damage to
(6 ) both the all metal and sandwich construction
-14 )
trailing edges .
ALL METAL
Trailing edge repairs to all-metal construction

assemblies and/or control surfaces are performed
(7) using basically the same procedures outlined in
0
section one of this chapter, titled “ Damage

0
a • :) . Repair Procedures.”
0
MHANHNH
ina The lap or flush patch may be used , depend
Vimane muu VOU'NUNI : ing on the size of the damage, type aircraft, and
the assembly or control surface to be repaired .
ASSEMBLED REPAIR NOTE : Normally, the flush patch is used on
control surfaces to insure aerodynamic smooth
ness .
YALUKOHARI CHIHUIMAHIK SANDWICH CONSTRUCTION
SECTION A - A A typical trailing edge repair to a sandwich

construction assembly is shown in figure 7-23 .
AM.362 RIVETING PROCEDURES
( 1) Assumed damage. (2) Damage cut out to a smooth
rectangle. (3 ) Rivet pattern. (4) Nonflush patch plates. The AMS must use his knowledge , ability, and
(5) Wood filler. (6) Rivet patterns. (7 ) Nonflush rivets experience when planning an aircraft structural
installed .
repair. This does not end after the proper
Figure 7-22.–Balsa wood repair with nonflush patch. materials have been selected . Each type of rivet
must be selected and driven in a precise manner
to meet riveting specifications. Some of the
177
CUT OUT DAMAGED AREA WITH 0.5

INCH MINIMUM RADII IN
THE CORNERS .
FILL EDGES OF TRIMMED AREA WITH

SPECIFIED FILLER .
MASK OFF AREA 2 INCHES FROM THE
INTENDED CUTOUT.
REMOVE PAINT AND CHEMICAL
SURFACE TREATMENT.
PATCH
ADHESIVE
1-1 / 2 INCHES CORE REPLACEMENT FILLER
-----
I INCH
EXISTING STRUCTURE
(MAX ) REPAIR PARTS
een CORE FILLER
FILLER
1-1/ 2 3 INCHES (MAX ) 1-1 / 2

INCHES INCHES
AM.363
Figure 7-23.-Trailing edge repair ( sandwich construction ).
specifications are rivet spacing and edge dis by one made of 2017 aluminum alloy unless the
1
tance , diameter of rivet hole, aerodynamic 2017 rivet is a size larger. Similarly , when 2117
smoothness , and size of the rivet bucktail. These rivets replace 2017 rivets the next larger size
can be accomplished only through determina should be used .
tion , practice, and accurate manipulation of all 2. When rivet holes become enlarged , de
standard layout and riveting equipment. formed , or otherwise damaged, use the next
larger size as replacement.
3. Countersunk -head rivets are to be replaced
RIVET SELECTION by rivets of the same type and degree of
countersink , either AN426 or MS20426 .
The following rules govern the selection and 4. All protruding head rivets are to be
use of rivets in making a repair: replaced with universal head , either AN470 or
MS20470.
1. Replacements must not be made with 5. Rivets of smaller diameter than 3/32 inch
rivets of lower strength material unless they are will not be used for any structural parts, control
larger than those removed . For example, a rivet parts, wing covering, or similar parts of the
of 2024 aluminum alloy should not be replaced aircraft.
178
rivet center. TRANSVERSE PITCH is the dis

tance between rows of rivets and is measured
tot
from rivet center to rivet center. EDGE DIST
ANCE is the distance from the center of the
rivet to the edge of the material being riveted .
There are no specific rules which are ap
plicable to every case or type of riveting. There
are, however, certain general rules which should
1 1/2 D be followed.
Rivet Spacing
Rivet spacing (pitch) depends upon several

factors, principally the thickness of the sheet,
G - GRIP ( TOTAL THICKNESS ) diameter of the rivets, and the manner in which
D - DIAMETER OF RIVET the sheet will be stressed. Rivet spacing should
never be less than 3D ( 3 times the rivet
1 1/2 D+G =TOTAL LENGTH OF RIVET
diameter ). Spacing is seldom less than 4D nor
more than 8D .
Transverse Pitch
AM.364
Figure 7-24. -Rivet length . When two or more rows of rivets are used in a
repair job, the rivets are staggered to obtain
6. Minimum rivet diameter is one times the maximum strength . The distance between the
thickness of the thickest sheet to be riveted. rows of rivets is called transverse pitch. Trans
7. Maximum rivet diameter is three times the verse pitch is normally 75 percent of existing
thickness of the thickest sheet to be riveted . rivet pitch but should never be less than 2 1 /2D.
8. The proper length of rivet is an important
part of the repair. Should too long a rivet be Edge Distance
used , the formed head will be too large, or the
rivet may bend or be forced between the sheets Edge distance for all rivets, except those with
being riveted . Should too short a rivet be used , a flush head, should not be less than 2D (twice
the formed head will be too small or the riveted the diameter of the rivet shank ) nor more than
material will be damaged. The length of the rivet 4D. Flush-head rivets require an edge distance of
should equal the sum of the thickness of the at least 2 1 /2D. If rivets are placed too close to
metal plus 1 1/2 times the diameter of the rivet, the edge of the sheet , the sheet is apt to crack or
as shown in figure 7-24. The formula for pull away from the rivets ; and if placed too far
determining rivet length is specified as follows: away from the edge, the sheet is apt to turn up
at the edge.
1 1/2 D + G = L, NOTE : On most repairs, the general practice is
to use the same rivet spacing and edge distance
where D = rivet diameter , G = grip ( total that the manufacturer used in the surrounding
thickness of material), and L = total length of area , or the Structural Repair Manual for the
>
rivet. particular aircraft may be consulted. Figure 7-25

illustrates rivet spacing and edge distance.
SPACING AND EDGE DISTANCE
DRILLING RIVET HOLES
RIVET SPACING , also referred to as RIVET
PITCH , is the distance between rivets in the Standard twist drills are used for drilling rivet
same row, and is measured from rivet center to holes. Table 7-1 specifies the size drill for the
179
Locations for the rivet holes should be center

punched and the drilling done with a power
drill, either electric or pneumatic . Electric drills
B constitute a fire hazard when drilling on or near
an aircraft due to the arcing of the brushes,
therefore, the pneumatic drill must be used . The
center-punch mark should be large enough to
701
A prevent the drill from slipping out of position,
but must not be made with enough force to dent
O o the surrounding material. (See fig. 7-4 .) The
drilling can be done with a hand drill if no
power drill is available . All burrs must be
removed before riveting by using a larger size
drill, or by using a deburring tool.
>
A-EDGE DISTANCE
Use of Portable Drills
B -RIVET PITCH
C TRANSVERSE PITCH Before using a drill, turn on the power and
>
( DISTANCE BETWEEN ROWS ) check it for trueness and vibration . Do not use a
drill bit that wobbles or is slightly bent.
T :ueness may be visibly checked by running the
motor freely.
AM.365 The most common error made by the in
Figure 7-25. -Rivet spacing and edge distance. experienced man is to hold a portable drill at an
incorrect angle to the work . Make sure the drill
is held at right angles to the work . When drilling
Table 7-1 . -Drill sizes for various size rivets.
in a horizontal position, it can be seen if it is too
far to the right or left, but it is difficult to tell if
the rear of the drill is too high or too low . Until
the AMS learns how to hold a drill at the correct
Rivet Drill Drill
diameter size size angle, he should have another man sight the
angle before starting the drill.
3/32 No. 41
Another common mistake is to put too much
0.0960
pressure on the drill. Pushing or crowding a drill
1/8 No. 30 .1285 may break the drill point, cause the drill to
plunge through the opposite side of the sheet,
5/32 No. 21 .1590 leaving rough edges around the hole, or cause
the drill to side slip on the metal causing hole
3/16 No. 11 .1910 elongation.
The drill should not be stopped immediately
1/4 No. F .2570 upon breaking through , but should be inserted
for approximately half its length while still
5/16 No. P. .3230
running, and then withdrawn . This operation
3/8 No. W .3860 requires judgment and skill since it is very easy
to ream the hole oversize ; but if this is done
properly , cleaner holes will result.
FLUSH RIVETING
various size rivets . Note that there is a slight
clearance in each case, which prevents binding of Progression has been made possible towards
the river in the hole. higher speed aircraft by improved design,
180
al
H
MALE DIE
MALE DIE
GUIDE
RAM
FEMALE
DIE
AM.336
Figure 7-26.-Dimple countersinking.
stronger and lighter aluminum alloys, and more Dimple Countersinking

powerful engines. Attention has been turned
towards the elimination of protruding head Dimple countersinking is accomplished by
rivets on the exterior surfaces of aircraft. In using male and female dies ( fig. 7-26 ). The
fabricating stressed metal skin on modern air female die shown in figure 7-26 has incorporated
craft, all exposed rivet heads must be counter in it a spring-loaded ram which flattens the
sunk to lie flush with the outer surface of the
bottom of the dimple as it is formed . This
skin . It is essential to provide an aerodynamical prevents cracks from forming around the
ly smooth surface.
dimple. The forming of a dimple is a combined
Flush rivets are more difficult to install, since bending and stretching operation. A circular
the parts being riveted must be countersunk, bend is formed around the hole. As in any
which is one extra operation following drilling. bending operation , the tension force at the
Another hazard is the closeness of the rivet set upper side of the bend (break) creates the radius
to the metal during riveting. If considerable skill at the junction of the two surfaces - the top side
is not used , the metal will be damaged by the of the sheet and downward bent inner wall of
rivet set . Flush rivets are made with heads of the dimple depression . The stretch occurs
several different angles, but the 100 -degree rivet around the hole as it is displaced from its
is standard for all Navy aircraft. original position and relocated at the bottom of
the dimple. The female die must have a slightly
The two methods used in countersinking for larger cone diameter than the corresponding
flush riveting are dimple and machine counter dimension of the male die. This allows for
sinking. In some instances, a combination of the material thickness and to relieve the bending
two may be used ; in other words, the top sheet load at the break in order to avoid circum
of an assembly may be dimpled while the under ferential cracks around the boundaries of the
sheet is machine countersunk . dimple. As a further safeguard, a slight radius is
181
THERMO DIMPLE GUN
DIMPLING SQUEEZER
CONTROL UNIT
O
DO
PO
J OO
Pro
0
AM.367
Figure 7-27. -Hot dimpling kit.
made on the female die at the junction of the more brittle materials is advantageous for the
top face with the dimple depression . reduction of cracking and also from the stand
1
Dimpling dies are made to correspond to any point of dimple shape . The heat is applied to the
size and degree of countersunk rivet head material by the dies , which are maintained at a
available. The dies are numbered , and the specific temperature by electrical heaters. The
correct combination of dies to use is indicated in heat is thus transferred to the material to be
charts specified by the manufacturer. Both male dimpled only momentarily and none of the
and female dies are machined accurately and heat- treat characteristics of the material are lost .
have highly polished surfaces. When dimpling a There are several models of dimpling
hole, place the material on the female die and machines used in the Navy , from the bulky floor
>
insert the male die in the hole to be dimpled . models to portable equipment. One of the most
The dies are generally brought together, forming popular portable types is shown in figure 7-27.
the dimple by a mechanical or pneumatic force . Basically , it has three units — the dimpling con
-
HOT DIMPLING . -As newer aluminum alloys

-
trol unit , dimpling squeezer, and the thermo
were developed to increase the shear and tensile dimple gun .
strength , they became increasingly difficult to The dimpling control unit is a small compact
form , since these alloys are harder and more unit designed to regulate automatic control
brittle . These aluminum alloys are subject to dimple die temperatures, prepressure , dwell
cracking when formed or dimpled cold . For this time, and final forming pressure. This same unit
reason , it is necessary to use a hot dimpling is used with both the hot dimpling squeezer and
process. The application of hot dimpling to the the thermo dimple gun .
182
-Dwell
7-2
.Table
chart
time
-temperature
Tool
Equipment Material
AT259
Portable
squeezer -T6
7075S 6°FMALE
- 50
O °F
- 50
6FEMALE
o ° ivets
R
AN426-100
thickness
Material .016 .020 .025 .032 .040 .051 .064 .072 .081 .091
numbers
Die
Size
Male Female
1.5 /1.5
1.5
1.5 1.75 11.75 1.75
3/32 -3
AT252DA -3
AT251DA
15 15 20 30 30
/1.5
1.5
/
1.5 1.5 2.0
/
1.5 2.0 2.0
1/8 AT252DA
-4 -4
AT251DA
15 15 15 15 20 20 30 35
183
1
//.5
1.5 1 .5
/1.5 2.0 2.25
5/32 AT252DA
-5 -5
AT251DA
15 15 15 15 20 30 35 40
1.5 1.5 .5
1/1.5 1.25 2.0 2.0
3/16 -6
AT252DA -6
AT251DA
20
15 30 35
/1.5
1.5
1.25
1.5
1/4 -8
AT252DA -8
AT251DA
15 15 15 15 25 30
D
chart
:towell
Key Dwell
pressure
in
seconds
.
in
time pounds
.
The hot dimpling squeezer is specially

lesigned for use where stationary squeezer
operation is impractical and some times
DIMPLING DIMPLING
mpossible . It is capable of working all material PRESSURE HIGH PRESSURE LOW
cages up to and including 0.091 inch . The
queezer type is designed to dimple in areas that
re inaccessible to other types of equipment. STRAIGHT EDGE
Tale and female dies are independently heated
y heaters operated from an electrical source.
The heaters produce a short heat-up and DIMPLING
PRESSURE CORRECT
ecovery time. The male die is adjustable for
-TEST
maximum squeeze for all gages of material. Also SPECIMEN
ncorporated is a cooling feature which affords
ase of handling and also reduces the power loss
lue to heat interference .
The thermo dimple gun is used to dimple in AM.368
he center of panels and in those areas otherwise Figure 7-28 . - Checking dimple equipment air pressure.
naccessible to yoke type dimpling equipment.
When being used on the aircraft, the thermo imaginary lines cross is the information block
limple gun drives the dimple from the exterior denoting the required dwell time in seconds and
vhile the female die and dolly bar are used on
dwell pressure in pounds. In this case the dwell
he inside. The thermo dimple gun is aircooled , time is 1.5 seconds and the dwell pressure is 20
eliminating the need for cumbersome heat pounds.
esistant gloves. This tool is small, compact , well When setting up any dimpling equipment ,
palanced , and easy to handle. follow the step-by-step procedure outlined in
Operation of the Hot Dimpler.-Prior to the Operating and Maintenance Manual supplied
etting the dimpling control unit up for with the equipment . Since equipment types
limpling, the AMS should refer to the equip vary , it is impractical to specify a standard
nent manufacturer's dwell time chart . ( See table procedure in this course . However, there are
7-2 .) Select the proper chart, taking into con four general requirements of a dimple, and by
ideration which type of equipment is to be used examining each, it is possible to denote
ind the material to be dimpled. Notice in table improper setting up of equipment.
7-2 the type of equipment is a portable squeeze 1. Sharpness of definition. It is possible to
суре and the material being dimpled is get a dimple with a sharp break from the surface
7075S - T6. The temperature required for both into the dimple . The sharpness of the break is
he male and female dies is 650 ° F. The second controlled by two things ( 1 ) amount of pressure
ine indicates the rivet to be used , in this case, and ( 2) material thickness.
100 degree countersink rivet. The third line 2. Condition of dimple. The dimple must be
ndicates the gage of material to be dimpled. The checked for cracks or flaws that might be caused
ower left side of the chart indicates the by damaged or dirty dies, or by improper
>
Hiameter of rivet to be used and part numbers of heating.

both the male and female dies. The chart is used 3. Warpage of material. The amount of warp
n this manner : If 0.040 material was being age may be held to a minimum if the correct
limpled, using 1/8 inch diameter rivets, the pressure setting is held. When dimpling a strip
AMS should draw an imaginary line down the with too much pressure, the strip tends to form
0.040 column and across the chart on the a convex shape as shown in figure 7-28 . When
1/ 8 -rivet size line. At the point where the two insufficient pressure is used it tends to form a
184
FIBRE COLLAR
CHIP OPENING
CUTTER
LOCK NUT
CUTTER SHAFT
ot
PILOT
BODY
STOP
ASSEMBLY
AM.369
Figure 7-29 . - Stop -type countersink .
thickness. A countersink has a cutting face

beveled to the angle of the rivet head and is kept
centered by a pilot shaft inserted in the rivet
COUNTERSUNK
100 DEEP
DIMPLED
TOO DEEP
COUNTERSUNK
TOO SHALLOW
DIMPLED
TOO SHALLOW
hole. A stopping device automatically acts as a
depth gage so that the hole will not be counter
sunk too deep . Figure 7-29 shows a stop-type
countersink .
The countersink should always be equipped
with the fiber collar shown in figure 7-29 , to
COUNTER SINK IMPERFECT
CROOKED DIMPLING prevent marring of the metal surface. A hand ,
electric , or air drill may be used to operate the
AM.370
countersink , and should not be operated above
>
Figure 7-30 . - Incorrect countersinking.

2,500 rpm . The countersink must be sharp to
avoid vibration and chatter. Figure 7-30 il
concave shape. This can be checked by using a lustrates several effects of incorrect counter
straight edge. sinking.
4. General appearance. The dimple should be
checked with the fastener that is to be used,
RIVET DRIVING PROCEDURE
making sure it meets the flushness requirement.
This is important as the wrong type or size dies
are sometimes used by mistake. Before driving any rivets, make sure all holes
line up perfectly, all shavings and burrs have
Machine Countersinking been removed, and the parts to be riveted are
fastened securely together. It is important that
Machine countersinking is used for flush the sheets be held firmly ' together in the
riveting all sheet 0.064 inch and greater in immediate area of the rivet being driven .
185
To adjust the speed of the gun , place it taps may mean “ bad rivet, remove and drive
against a block of wood. Never operate a rivet another" ; and so on.
gun without resistance against the set , as the The upset head, often referred to as the buck
vibrating action may cause the retaining spring tail, should be one and one -half times the original
to break , allowing the set to fly out. diameter of the original shank in width and one
CAUTION : A rivet set can be a deadly half times the original diameter in height as
weapon . If a rivet set is placed in a rivet gun shown in figure 7-31 . If the head thus formed is
without a set retainer and the throttle of the gun narrower and higher than the dimensions given,
is opened, the rivet set may be projected like a more driving is necessary . If it is wider and
bullet . This may cause either severe injury to a shallower, it must be removed and replaced .
person or the destruction of equipment .
The gun should be adjusted so that the rivet RIVET REMOVAL
may be driven in the shortest possible time , but Rivets must be removed and replaced if they
care must be taken not to drive the rivet so hard
or in such a manner as to dimple the metal . show even the slightest deformity or lack of
Practice will enable one to properly adjust a gun alignment. Among the reasons for replacing
for any type of work . rivets are the following: Rivet marred by
When the rivet has been pushed into proper bucking bar or rivet set ; rivet driven at slant, or
position and held there firmly with the set of shank bent over ; rivet too short, causing head to
the rivet gun resting squarely against the rivet be shallow ; rivet pancaked too flat from over
driving; sheets spread apart and rivet flashed
head, the bucking bar is held firmly and squarely
against the protruding rivet shank . (In most between sheets ; rivet driven too lightly, causing
sheets to buckle ; two rivet heads not in align
instances, the bucking bar must be manipulated
ment ; and head of countersunk rivet not flush
by another man, called the bucker.) The gunner
with outside surface or driven below surface .
then exerts pressure on the trigger and starts
driving. The gun must be held tightly against the Examples of these incorrectly driven rivets are
rivet head and must not be removed until the shown in figure 7-32 .
trigger has been released.
The bucker removes the bucking bar and
checks the upset head after the gunner has
stopped driving. A signal system is usually DRIVEN AT UNDER OFF CENTER
OVER DRIVEN
employed to develop the necessary teamwork SLANT DRIVEN
and consists of tapping lightly against the work .

One tap may mean “ not fully driven, hit it
again " ; two taps may mean “ good rivet" ; three
HOLE TOO HEAD HEAD NOT DOLLY OFF
LARGE NICKED FLUSH HOLE CENTER
TOO SMALL
xD
T
-1 /2xD -14D --** SHEETS NOT HARD RIVET RIVET DIE HOLES IN SHEET
HELD TOGETHER IN SOFT NICKED NOT ALIGNED
RIVET FLASHED METAL SHEET
AM.371
Figure 7-31 .-Rivet dimensions before and after AM.372
bucking. Figure 7-32. - Incorrectly driven rivets.
186
FILE A FLAT ON MANUFACTURED CENTERPUNCH THE FLAT . DRILL THROUGH THE HEAD .
HEAD. USE DRILL ONE SIZE
SMALLER THAN RIVET
SHANK .
REMOVE WEAKENED HEAD WITH PUNCH OUT

SHARP CHISEL . RIVET
AM.373
Figure 7-33 . - Removal of rivets.
When removing rivets, care should be taken head, the shank should be drilled out. However,
not to enlarge the rivet hole , as this would if the sheet is firmly supported from the
necessitate the use of a larger size rivet for opposite side , the shank may be punched out
replacement . To remove a rivet, file a flat with a drift punch. (See fig. 7-33 .)
surface on the manufactured head if accessible .
It is always preferable to work on the manufac The removal of flush rivets requires slightly
tured head rather than on the one that is more skill. If the formed head on the interior is
bucked , since the former will always be more accessible and has been formed over heavy
symmetrical about the shank . Indent the center material such as an extruded member, the
of the filed surface with a center punch and use formed head can be drilled through and sheared
a drill of slightly less than shank diameter to off, as mentioned above . If the material is thin,
drill through the rivet head . Remove the drill it may be necessary to drill completely through
and , with the other rivet end supported , shear the shank of the rivet and then cut the formed
the head off with a sharp chisel . Always cut head with diagonal cutting pliers. The remainder
along the direction of the plate edge . If the of the rivet may then be drifted out from the
shank is unduly tight after the removal of the inside .
187
G - II HAND GUN .
YOQ ...
G - 15 (SERIES) POWER GUN

7 G - 6H DRAW BOLT
.
n
nou
un
no
an nd
Wo
po
Ma
23 .
1
G - 6H COUNTERSUNK
HEAD SLEEVE
G - 6H UNIVERSAL HEAD SLEEVE
AM.374
Figure 7-34 . - Self- plugging rivet (friction lock ) installation tools.
BLIND RIVET INSTALLATION the G -11 hand gun . The G -40 power gun uses
the H -40 pulling heads primarily ; however,
The description and use of blind rivets are through the use of a 226 adapter, G -6H heads
covered in chapter 6. The special tools and may be used . Extensions are available for all
installation and removal methods are covered in guns using G -6H heads. Figure 7-34 shows the
the following sections. Selection of the proper G - 11 and G -15 rivet guns with the G -6H pulling
equipment depends on a number of variables; heads .
space available for equipment , type of rivets to The heads are manufactured in three different
be driven , availability of air pressure , etc. sizes to accommodate the different rivet
diameters. For ease of selection , the sizes are
Installation Tools for stamped on the parts of the pulling head.
Friction Lock Rivets
Installation Procedures
The guns used for installing this type of
self-plugging rivet are the G -11 hand gun and the It is important that the proper drawbolt and
G - 15 (series) and G -40 (series) power guns. The sleeve be used for the rivet being installed . The
G - 15 power gun uses G -6H pulling heads as does drawbolt should correspond to the diameter of
188
head of the rivet firmly , and to insure contact

between the parts being riveted . Pull the trigger
until the stem breaks. The stem will be ejected
RIVET INSERTED
IN MATERIAL
through the rubber tube at the back of the gun
head . It is important that this tube be in place in
GUN HEAD order to prevent stems from getting into the gun
INSTALLED mechanisms.
OVER STEM
Inspection
DIRECTION OF PULL
BY GUN BOLT
The rivet is satisfactory if the pin is firm and
the head is seated tightly on the face of the
STEM PULLED
material. Occasionally, the head will rise slightly
in the area which was under the slot of the
AND BROKEN ,
GUN FREED , pulling head . This condition is acceptable if the
RIVET UPSET head is not too badly deformed and the tension
characteristics of the joint are not made critical
by the deformation of the head . Figure 7-36
illustrates satisfactory and unsatisfactory self
STEM TRIMMED plugging rivets.
INSTALLATION
Removal
COMPLETE
These rivets are removed in much the same

manner as the common , solid shank rivets,
except for the preliminary step of driving out
AM.375
the rivet stem . (See fig. 7-37 . )
Figure 7-35. -Self-plugging rivet (friction lock) 1. Punch out the rivet stem with a pin punch .
installation .
2. Drill out the rivet head , using a drill
the rivet, and the sleeve should correspond to slightly smaller than the rivet shank .
the rivet diameter and head style . Speed of 3. Pry off the weakened rivet head with a pin
installation may be increased by inserting a punch .
number of rivets in the work and then applying 4. Push out the remainder of the rivet shank
the gun . In other instances, such as overhead with a pin punch . If the shank will not push out,
work , it is apparent that this method would be drill the shank , taking care not to enlarge the
impractical and the rivet should be loaded into hole in the material. If the hole should be
the gun and then inserted into the prepared enlarged, finish -drill for an oversize rivet.
hole. The rivet must be completely inserted into
the slot in the drawbolt, because improper Installation Tools for
Mechanical Lock Rivets
seating of the rivet may permit the head to
break off before the rivet is properly set . (See
fig. 7-35.) When using a hand gun , hold the rigid One of the tools used for driving these rivets
handle of the gun parallel to the rivet axis. Open is the CP350 blind rivet pull tool. (See fig. 7-38 .)
the movable handle as far as it will go , then The nose of the tool includes a set of chuck jaws
partially close. Repeat this operation until the which fit the pull grooves in the rivet pin and
rivet stem breaks , then release the gun by pull it through the rivet shank to drive the rivet;
completely closing the movable handle. When an outer anvil which bears against the outer part
using the power gun, hold the head of the gun of the manufactured head during the driving
parallel to the axis of the rivet. Push the gun operation ; and an inner anvil which advances
against the work with enough force to seat the automatically to drive the locking collar home
189
HH
SATISFACTORY UNSATISFACTORY
11
T
GRIP LENGTH TOO SHORT
FOR MATERIAL THICKNESS
H Du
a
1
UNDERSIZE OVERSIZE
HOLE HOLE
AM.376
Figure 7-36 . - Inspection of self-plugging rivets (friction lock) .
after the blind head is formed . A short nose relief valve operation pressure is properly
assembly , interchangeable with the standard adjusted for the size rivets being driven . Also
assembly , is available for use in areas where make sure that the rivets are of proper length.
there is not sufficient clearance for the standard The tool has only one operating adjustment.
nose . This adjustment is used to control the pull on
A change in rivet diameter requires a change the pin at which the inner anvil advances. The
in chuck jaws, outer anvil, inner an vil, inner desired amount of the pull depends on the
anvil thrust bearing, and an adjustment of the diameter of the rivets to be installed , and the
shift valve operating pressure as described below . pull is varied by changing the pressure at which
A change in the rivet head type from universal the adjustable shift valve operates. To adjust,
head to countersunk head, or vice versa , requires proceed as follows:
a change of the outer anvil only , if there is no
>
change in the rivet diameter. 1. Remove pipe plug from tool cylinder and
A special chuck jaws assembly tool is connect a pressure gage to the tool .
furnished with the tool. To facilitate in sertion of 2. Press trigger and release it the instant a
the chuck jaws into the chuck sleeve , mount the puff of exhaust indicates that the shift valve
three jaws on this assembly to form a cone , and controlling the inner anvil has shifted . The gage
lower the inverted chuck sleeve over the jaws. will then indicate the shift pressure. See table
Always be sure that the pull tool is equipped 7-3 for the approximate pressures.
with the correct size chuck jaws, outer and inner NOTE : The trigger must be released im
anvils to fit the rivets being driven, and that the mediately as the valve shifts. Otherwise the gage
190
down the line pressure to 60 psi with an air

regulator , part number 900-102 , attached to the
air inlet bushing. When using a CP350C rivet pull
tool to drive 1 / 16- and 5/32-inch diameter
PUNCH rivets, use air inlet bushing, part number 81479 ,
To DRILL HEAD ONLY

and shift valve stop, part number 83731. When
driving 1 / 8 -inch diameter rivets, use air inlet
bushing, number 83642, and cut down the line
pressure to 60 psi with air regulator, part
number 900-102 , attached to the air inlet
bushing.
>
Installation Procedures
Proper driving procedures are vital to obtain a

K
firm joint . The recommended procedures are as

follows:
1. Hold the head of the gun steady and at

right angles to the work .
2. Press on the head of the gun hard enough
電 to hold the rivet firmly against the work . Do not
use a great amount of pressure unless necessary
to bring the part being riveted into contact .
AM.377
3. Squeeze the gun trigger and hold until the
Figure 7-37. -Removal of self-plugging rivets rivet pin breaks, then release the trigger. The
( friction lock). next rivet should not be driven until the return
action has caused the gun to latch . A distinct
will record the higher pressure which builds up click will be heard, indicating that the gun is
as soon as the valve has shifted. ready for the next installation cycle .
3. To adjust the pressure , loosen the valve
adjusting screw locknut and turn the valve Figure 7-39 shows the complete installation
adjusting screw clockwise to increase pressure , of a self -plugging (mechanical lock) rivet.
or counterclockwise to decrease pressure , until The rivet is actually cold -squeezed by the
the desired pressure is obtained. Check the action of the pin head drawing against the
pressure after tightening the valve -adjusting hollow shank end. Shank expansion through the
screw locknut . When rivets of extremely long action of the extruding angle, blind head
grip length are to be driven an adjustment to the formation, and setting of the mechanical lock in
high pressure limit should be made . For efficient the rivet head all follow in automatic sequence
operation of the tool, the minimum desired line and require but a fraction of a second . In some
pressure should be not less than 90 psi and the places such as near the trailing edge of a control
maximum not more than approximately 110 psi. surface, there may not be sufficient space
When using a CP350 A or B rivet pull tool , it between the two surfaces to insert the rivet.
may be necessary to increase the inside diameter In such cases , the pin may be forced into the
of the air inlet bushing, part number 81479 , hollow shank until the head of the pin just
from 0.055 to 0.065 inch when driving touches the end of the shank . Since no further
3 / 16 - inch diameter rivets if the line pressure is shank expansion will result, the drill hole should
below 90 psi . When driving 1 /8-inch diameter not be enlarged to provide a free fit of the
rivets, it may be necessary to use air inlet already expanded rivet. To insert the rivet, use a
bushing, part number 82642, having a 0.040 >
hollow drift pin which will accommodate the
inch inside diameter . If the tool " flutters,” cut rivet pin and the locking collar. (See fig. 7-40.)
191
OUTER
CHUCK ANVIL
JAWS
INNER
0
TRIGGER ANVIL
LONG NOSE ASSEMBLY
CP 350
BLIND RIVET
PULL TOOL
AIR INLET BUSHING SHORT NOSE ASSEMBLY

I PIPE PLUG
LOCKNUT
VALVE ADJUSTING SCREW

AM.378
Figure 7-38 . - Self- plugging rivet (mechanical lock) pull tool .
Table 7-3 . - Adjustments for CP350 blind rivet pull The mechanical lock feature increases the load
tool. carrying capacity in single shear from about 10.3
percent in the case of thick sheets where joint
strength is considered critical in rivet shear, to as
much as 63.3 percent in thin sheets where sheet
Rivet Shift valve operating bearing is considered critical.
diameter pressure
Inspection
1/8 30 to 31 psi
Visual inspection of the seating of the pin in
5/32 46 to 47 psi the manufactured head is the most reliable and
simple means of inspection. If the proper grip
3/16 66 to 67 psi length has been used and the locking collar and
broken end of the pin are approximately flush
with the manufactured head, the rivet has been
properly upset and the lock formed . Insufficient
grip length would be indicated by the pin
This allows a driving force to be exerted on the breaking below the surface of the manufactured
head of the rivet. Drive the head into firm head, and excessive grip length would be
contact with the sheet and then apply the rivet indicated by the pin breaking off well above the
pull tool in the usual manner to upset the rivet. manufactured head. In either case, the locking
Due to the mechanical lock feature of the pin collar might not be properly seated , thus form
and sleeve , the driven rivet is substantially the ing an unsatisfactory lock . Table 7-4 gives limits
mechanical equivalent of a one -piece solid rivet. for proper pin seating.
192
Mechanical - lock rivet before installation .

( 1 ) Note shorter stem on blind side providing
marked improvement for limited blind
clearance applications .
NOTE SHEET GAP
As the stem is pulled into the rivet sleeve ,

it immediately forms the blind head . The
( 2) mechanical - lock always forms the blind head
firmly against the blind sheet .
m
Continued movement of the stem pushes the
(3) blind sheet ahead of the blind head until
the sheets are firmly clamped together and
the rivet is firinly seated .
SHEET GAP
CLAMPED TOGETHER
The plugging portion of the stem expands

the rivet sleeve to fill the hole and re
(4 ) duces in diameter as it passes through the
rivet sleeve , providing excellent hole fill
-even in oversize holes .
The movement of the stem is stopped by

the pulling head at a point where the
(5) groove in the stem and the chamfer in
the rivet line up to make a receptacle
for the locking ring .
The pulling head shifts automatically ,

(6) inserts the positive mechanical locking
vi ring , and fractures the stem flush with
the rivet head ,
AM.316
Figure 7-39. - Self-plugging rivet (mechanical lock ).
193
3. Use the proper size drill to drill nearly

through the rivet head . For a 1 /8 -inch diameter
RIVET PIN PRESSED INTO
SLEEVE BEFORE INSERTION rivet, use a number 31 drill; for a 5/32 , use a
number 24 ; and , for a 3/16, use a number 15 .
4. Break off the drilled head , using a drift pin
as a pry .
5. Drive out the remainder of the rivet with a
pin having a diameter equal to, or slightly less
HOLLOW DRIFT PIN
than, the rivet diameter.
Installation Tools for Rivnuts

AM.379 Tools used in the installation of Rivnuts
Figure 7-40. - Inserting self-plugging rivet
( mechanical lock) .
include the heading tool and the keyway cutter.
The heading tool , as shown in figure 7-42, has a
threaded mandrel onto which the Rivnut is
Table 7-4.-Inspection criteria for self-plugging threaded until the head of the Rivnut is against
rivets (mechanical lock). the anvil of the heading tool . This tool normally
comes in three different sizes. They are
identical , except for the size of their threaded
mandrel. The heading tool comes in sizes 6-32,
Rivet С 8-32, and 10-32 which correspond with the
А B
diameter thread sizes of the standard Rivnuts. The key
0.012 0.016 0.008
way cutter is used for cutting a notch in the
1/8 inch Rivnut hole for the Rivnut keyway. In some
5/32 inch .015 .020 .010
.018 .024 .012 instances the keyway cutter cannot be used
3/16 inch because the material is too thick . If such is the
A. Maximum allowable distance of locking col case , use a small round file to form the keyway.
lar above or below rivet head.
B. Maximum allowable distance of top of land Installation Procedures
on pin above rivet head .
C. Maximum allowable distance of top of land The drilling of holes for Rivnuts requires the
on pin below rivet head . same precision as that required for solid shank
rivets. The shank of the Rivnut must fit snugly
in the hole . To obtain the best results for a
Removal flathead installation , first drill a pilot hole
Removal of this rivet is accomplished easily smaller than the shank diameter of the Rivnut,
then ream to the correct size . Pilot and ream
without damage to the work by use of the
following procedure: (See also fig. 7-41.) drill sizes for Rivnuts are given in table 7-5 .
The application of flush Rivnuts is subject to
1. Shear the lock by driving out the pin , certain limitations. For metal which has a
using a tapered steel drift pin not over 3/32-inch thickness greater than the minimum grip length
diameter at the small end . If working on thin of the first Rivnut in a series, use the machine
material, back up the material while driving out countersink ; and for metal thinner than the
the pin. If inaccessibility prohibits this, partially minimum grip length of the first Rivnut in a
remove the rivet head by filing, or with a rivet series, use the dimpling process. The counter
shaver. An alternative would be to file the pin sunk Rivnut should not be used unless the metal
flat, center punch the flat, and carefully drill out is thick enough for machine countersinking, or
the tapered part of the pin forming the lock. unless the underside is accessible for the
2. Pry the remainder of the locking collar out dimpling operation . Aside from the countersink
with a drift pin . ing operation , the procedure for installing a
194
FILE A SMALL FLAT PRY OUT REMAINDER

ON RIVET HEAD OF LOCKING COLLAR
CENTERPUNCH FLAT
DRILL ALMOST THROUGH
RIVET HEAD
DRILL OFF TAPERED PORTION

OF PIN WHICH FORMS THE LOCK,
PRY OFF RIVET HEAD
ACCOMPLISH STEPS 1,2, AND 3

1
ONLY IF RIVET IS IN A THIN

OR RESILIENT MATERIAL
SHEAR LOCK TAP SHANK

BY DRIVING OUT WITH
OUT PIN PIN
AM.380
Figure 7-41. - Removing self-plugging rivets ( mechanical lock) .
flush Rivnut is the same as that for the flathead heading tool together until the Rivnut starts to
Rivnut. head over. Then release the handle and screw the
When installing Rivnuts , always check the stud farther into the Rivnut. This prevents
threaded mandrel of the heading tool to see that stripping the threads of the Rivnut before it is
it is free from burrs and chips from the previous properly headed . Again squeeze the handles
installation . Then screw the Rivnut onto the together until the Rivnut heading is complete.
mandrel until the head touches the anvil. Insert Now remove the stud of the heading tool from
the Rivnut in the hole (with the key positioned the Rivnut by turning the crank counter
in the keyway , if a key is used ) and hold the clockwise .
heading tool at right angles to the work . Press The action of the heading tool draws the
the head of the Rivnut tightly against the sheet Rivnut against the anvil, causing a bulge to form
while slowly squeezing the handles of the in the counterbored portion of the Rivnut on
195
HT TUTULUI TH
-NOTCHED
HOLES
HEADING
TOOL
!!!!M.
KEYWAY CUTTER
AM.381
Figure 7-42. - Hand -operated Rivnut heading and keyway cutter tools.
Table 7-5. -Drill sizes for Rivnuts. after the hole has been reamed . Operate the
keyway cutter by inserting it in the hole and
squeezing the handles. Always cut the keyway
on the side of the hole away from the edge of
the sheet.
Rivnut size 6-32 8-32 10-32
Pilot drill Inspection

19 (0.166) 8 (0.199) 1 (0.228)
size
After the installation of Rivnuts, as well as
Ream drill
12 (0.189) 2 (0.221) 1/4 " (0.250) other fasteners, the AMS must inspect the
size completed installations. The Rivnuts are
inspected for the following: Manufactured head
is inspected for correct installation of the Rivnut
keyway in its keyway slot, insuring it is flush
the inaccessible side of the work . This bulge is with the surface in which it is installed. The
comparable to the upset head on an ordinary threaded portion of the Rivnut shank is
solid shank rivet. The amount of squeeze inspected for cracks, stripped threads, and
required to head the Rivnut properly is best general condition . Threads that are found to be
determined by practice. stripped may have an improperly upset head.
When keyed Rivnuts are used, cut the keyway The stripped threads would also prevent the
196
installation of screws . When possible, in open fasteners are covered in chapter 6. The special
skin areas, inspect the shank for a properly upset . tools and installation and removal methods are
head . covered in the following sections.
NOTE : Rivnuts which are not to be used at
the time of installation, or not used for any Installation Tools for
other reason , should be plugged with a screw Hi- Shear Rivets
designed specifically for that purpose. This will
eliminate pockets, which could hold moisture The special tools required for use with Hi
and cause corrosion if left open. Shear rivets differ from conventional sets only in
the design of the collar swaging and trimming
Removal features and the discharge port through which
excess collar material is ejected. (See fig. 7-43 .)
Defective Rivnuts should be replaced by the Various tools and combinations of tools are
same size Rivnuts whenever possible . When the available for installing rivets in limited access
hole has been enlarged by removal, substitution areas .
of the next larger size can be made. To remove a
Rivnut, select a drill the same size as the original Installation Procedures
hole . Drill out the Rivnut head , using light
>
pressure and the hollow Rivnut shank as a guide. Figure 7-43 illustrates four steps in the
The Rivnut shank should fall out of the hole installation of the pin and collar to form the
behind the sheet, or it may be drifted out , using rivet. In step 1 , the pin is inserted into the work.
a pin punch . A bucking bar is placed against the head of the
pin . In step 2, the collar is slipped over the
SPECIAL RIVET AND grooved end of the pin . A gun or squeezer set is
FASTENER INSTALLATION placed over the collar. As driving pressure is
applied in step 3 , the collar begins to form into
The description and use of special rivets and the grooved end of the pin . Step 4 shows the
BUCKING BAR
( STEP )
a
HI- SHEAR RIVET SET
( STEP 2 )
I
EXCESS TRIM MATERIAL
( STEP 3 ) ( STEP 4 )
AM.313
Figure 7-43. - Hi-Shear rivet installation.
197
USE CHISEL THAT HAS CUTTING EDGE

NARROWER THAN COLLAR HEIGHT
PUNCH
BUCKING BAR TO
yo SUPPORT RIVET
STEP 1 . STEP 2 .
SPLIT RIVET COLLAR TWO PLACES DRIVE RIVET PIN OUT WITH PUNCH
( A ) CHISEL METHOD
DRILL BUSHING DRILL BUSHING
STEP 1 . STEP 1 .
DRILL SHANK DOWN DRILL THROUGH
TO LOCKING GROOVE
DRILL APPROXIMATE
RIVET HEAD
이
DRILL SAME SIZE
AS RIVET
SIZE OF RIVET
PUNCH PUNCH
STEP 2 . STEP 2 .
DRIVE RIVET PIN DRIVE RIVET PIN
OUT WITH PUNCH OUT WITH PUNCH
( B ) DRILL GUIDE METHOD

a
HOLLOW END MILL
PUNCH
STEP 1 . STEP 2 .
MILL COLLAR DOWN TO EDGE OF PIN GROOVE DRIVE RIVET PIN OUT WITH PUNCH
(C ) HOLLOW END MILL METHOD
AM. 16
Figure 7-44 . - Hi- Shear rivet removal.
198
collar formed or swaged completely into the

grooved end of the pin . Excess material is
trimmed off the collar automatically by the tool
during driving.
W Step 1 . Pin is inserted from
one side of work through pre
pared hole . Metal collar is
Removal then placed over the pintail .
When tool nose is applied ,
chuck jaws grip pull grooves .
Hi-Shear rivets may be removed by various
methods . However, only some of these methods
are recommended as the others may increase the
possibility of damaging the parts. Cutting the
collar off with a chisel or other sharp tool
should be done only where other methods are
DRIVING
not practical and the structure is fairly rigid. MTM
Step 2 . Tool pulls on pin
and starts drawing sheets
CYCLE
(See (A) fig . 7-44 .) Special care must be taken to together .
prevent damage to the part or to the hole. The

use of a drill guide is recommended in drilling
out aa Hi-Shear rivet. (See (B) fig. 7-44.) The base
of the guide has a conical surface which fits over
the driven collar. A drill with a diameter
approximately equal to the rivet diameter is
then used to drill the shank end of the rivet Step 3 . As the pull on the
117MM pin increases , tool anvil
down to the locking groove . The rivet is then AAN
tolmudilihat swages collar into locking
grooves and a permanent
driven out with a small punch. When absolutely lock is formed .
necessary , the head of the rivet may be drilled
>
out , but a guide should be used on protruding

head rivets.
A collar removal tool, consisting of a hollow
end mill, may also be used to remove the collar.
>
( See (C) fig . 7-44 .) The rotating cutter is applied Tool continues to
Step 4 .
to the collar until a sufficient amount of collar 0901144101 pull until pin breaks at the
material has been removed to permit a sharp tap breakneck groove and is ejected .
Tool anvil disengages from
of a hammer to drive out the pin . A stop swaged collar .
prevents the cutter teeth from contacting and

damaging the work surface.
Installation Procedures for AM.318

Lockbolt Fasteners Figure 7-45 . - Lockbolt installation .
Figure 7-45 illustrates four steps in the
installation of the lockbolt fastener. This Special care must be taken to prevent damage to
fastener is installed using the CP352 pneumatic the structure or to the hole . The most
driving tool (similar to the CP350 blind rivet acceptable method of removal is to cut the
pull tool illustrated in figure 7-38). collar off, using a hollow end mill in a drill
motor. After removal of the collar, the pin may
Removal be driven out with a punch .
Lockbolt collars may be removed by various Installation Procedures for

methods . In general the procedure is the same as Hi-Lok Fasteners
for removing Hi- Shear rivets. (See fig. 7-44 .)
Cutting the collar off with a chisel should be Hi-Lok fasteners may be installed by one
done only where the structure is fairly rigid. person working from one side of the work , using
199
MATERIAL COLLAR WRENCH TIP
MONACO
PIN
PIN HEX RECESS
Insert the pin into 2. Manually screw the collar 3. Insert the hex wrench tip of the
the prepared hole. onto the pin a minimum power driver into the pin's hex recess .
of two turns .
COLLAR POWER DRIVER INSTALLED FASTENER
COLLAR WRENCHINC
COLLAR WRENCHING
DEVICE DEVICE
4. Firmly press the driver against the 5. The Hi - Lok fastener is

collar , operate the power driver until installed with the correct
the collar's wrenching device has torque volue .
been torqued off.
( A ) HI - LOK INSTALLATION
( Power Tools )
Allen
Wrench
Allen
Wrench
Ratchet
Socket Water Pump Pliers

( B ) HI - LOK FASTENER ( C ) REMOVAL OF INSTALLED HI - LOK
INSTALLATION FASTENER
( Hand Tools ) ( Hand Tools )
AM. 17
Figure 7-46 . - Hi-Lok fastener installation and removal.
200
standard power or handtools and Hi-Lok adapter correct torque value as the collars are designed
tools. Hi-Lok adapter tools can be fitted to to break off (torque off ) at preestablished
high -speed power drivers in straight, 90 -degree, torque levels .
offset, and extension configurations. View (A)
figure 7-46 illustrates steps in the installation of Removal
Hi- Lok fasteners using power tools .
Hi-Lok fasteners may be installed using the Hi-Lok fasteners are easily removed with
following handtools : Allen hex key (Allen standard handtools in a manner similar to
wrench ) and open -end or ratchet-type wrenches. removing a nut from a bolt. To remove a Hi-Lok
(See ( B ) fig. 7-46 .) To install the fastener, insert fastener, insert an Allen wrench in the hex recess
the pin into the prepared hole and manually of the pin . Hold the Allen wrench firm and,
screw the collar onto the pin a minimum of two using a pair of channel-lock or vise -grip pliers,
turns. Insert the proper size Allen wrench into rotate the collar counterclockwise until re
the hex recess of the pin and, using a ratchet or moved . (See (C) fig. 7-46 .) Hi-Lok pins are
open -end wrench , rotate the collar clockwise reusable if no thread damage is incurred during
until the wrenching device of the collar has been removal. AN or NAS nuts may be substituted
torqued off. The fastener is installed with the for Hi-Lok collars.
RATCHET
WRENCH ADAPTER
NOSE ADAPTER
HANDLE
O.
SETSCREW
100001
0000001
STRUCTURE ( REF )
AM.299
Figure 7-47 . - Jo -Bolt installation tool.
201
Installation Tools for the correct size for different size and type of
lo - Bolt Fasteners Jo - Bolts. It is recommended that the holes be
drilled undersize and then be brought up to final
Special tools are required for the installation size for reaming. After bringing the holes up to
of Jo-Bolts. In no case shall power screwdrivers correct size and prior to installing the Jo-Bolts,
or drill motors be converted to Jo - Bolt driving the part to be joined must be secured firmly in
tools. The handtool illustrated in figure 7-47 position . Cleco fasteners, C-clamps , or any of
consists of a tool body, nose adapter, and
> several varities of temporary fasteners may be
wrench adapter which can be used for installing used for this purpose . Figure 7-48 illustrates the
all sizes and types of Jo-Bolt fasteners. The nose installation of Jo-Bolts . Insert the correct grip
adapter is secured in the tool body and prevents length Jo - Bolt in the hole. The fastener can be
he nut portion of the Jo-Bolt from turning pushed easily into a properly prepared hole and
during installation . The wrench adapter rides in no case shall it be driven forcibly into the
Free inside the nose adapter and gets its turning hole . A very light tap fit is permissible in
action from the ratchet wrench. aluminum alloy parts but not in steel . Select the
correct nose and wrench adapter for the fastener
nstallation Procedures and secure them in the handtool body . Place the
nose adapter of the driving tool over the slabbed
When installing Jo-Bolts it is important that portion of the bolt shank so that it engages the
he fastener holes and countersink diameters be head of the Jo-Bolt . On flush head Jo-Bolts the
.NORMAL INSTALLATION DRIVING TOOL

WRENCHING END
WRENCH OF BOLT
BOLT
ADAPTER NOSE
ADAPTER
BOLT
BREAK -OFF
NUT
Mohan
COLLAR
Step 1 Step 2 Step 3
Select proper grip length Engage nose adapter of When power is applied ,
then insert fas tener in tool with nut and slabbed the collar is compressed
hole . portion of bolt . over the tapered end of
the nut . The bolt is
notched to break off at
a predetermined tension
force .
INSTALLED PROTRUDING HEAD

WE
İNSTALLED FLUSH HEAD
THREADED BLIND FASTENER THREADED BLIND FASTENER
AM.327
Figure 7-48 . - Jo -Bolt installation .
202
dogs on the nose adapter shall fit into the slots turnlock fasteners. Three of the most widely
of the fastener head . On the protruding head, used turnlock fasteners are the Camloc, Dzus ,
including the millable head fasteners, the nose and Airloc.
adapter will fit over the fastener head . Hold the
tool tightly against the Jo-Bolt head and CAMLOC INSTALLATION TOOLS
perpendicular to the surface of the work . Failure
to hold the tool perpendicular may result in the The following list of Camloc tools should be
stem breakoff before the Jo-Bolt is tight. Hold available to assure satisfactory Camloc installa
ing the handle of the tool stationary , turn the tion , but does not represent the minimum tools
ratchet handle. As power is applied , the bolt is required for any particular installation :
turned while the nut is held . The sleeve,
Pliers , No. 4P3 .
compressed between the bolt head and tapered
end of the nut, is drawn over the end of the nut.' Snapring tool , No. T26.
The sleeve is expanded , forming the blind head Cutters, Nos. 4 -G2C and 4 -GC .
against the inner surface of the part. When the Hole saws, Nos. HS-471 D and HS-500.
sleeve is drawn up tight, the slabbed portion of Flaring tools, Nos . T -55-1 and T -50-1 .
the bolt is snapped on , completing the driving Dimpling tools , Nos . 4 -G200M , 4G200F,
operation . After driving, the end of the bolt, at 2-S200M, and 2 -S200F .
the breakoff point, should be touched up with
zinc chromate primer. CAMLOC REPAIR PROCEDURE
Removal Repair of Camloc fasteners includes removal

of the damaged stud, grommet, or receptacle ,
The procedure to be used for the removal of a proper preparation of the hole , and installation
Jo-Bolt will depend on whether the fastener is of the replacement part. In all cases, alignment
clamped up tight or whether it is loose . If the of the stud, grommet, and receptacle must be
Jo - Bolt is clamped up tight in the hole , it can be maintained . When structural repair of the access
removed by drilling just through the fastener door or access frame is necessary , all repair work
>
head and then driving out the shank portion should be completed before aligning receptacle
with a hammer and punch . ( See (A) fig . 7-49 .) If holes with stud or grommet holes.
the Jo-Bolt is loose in the hole , it must be Hole preparation is dependent upon the series
prevented from turning by using a drill bushing of fastener specified and the sheet thickness of
which has dogs to engage the head slots and a the material to which the fastener must be
handle or other device to hold it. (See ( B) fig. attached . All holes - plain , dimpled, counter
7-49 .) While holding the Jo-Bolt to prevent it sunk , or counterbored- should be predrilled
from turning, drill the bolt portion of the undersize with the size drill (pilot hole) recom
fastener completely out , removing the bolt head mended in the Structural Repair Manual for the
and fastener sleeve . After the bolt head and particular aircraft.
sleeve have been removed, pick out the nut Remove all chips and burrs before installing
portion of the fastener. For all drilling opera fastener parts . Select proper size stud, grommet,
tions on Jo-Bolts, select a drill motor that does and/or receptacle . In cases of varying sheet
not turn over 500 RPM . thickness which would cause high locking
torque , the stud assembly should be replaced
with one of suitable length to insure uniform
TURNLOCK FASTENER REPAIR low locking torque . Stud length increments of
0.030 inch allow for varying material thick
A number of approved turnlock fasteners are nesses. The total grip length for the stud
in use on aircraft. They are used to fasten small assembly includes both top and bottom sheet
removable inspection panels, doors, fairings, and thicknesses. Stud selection tables will be listed in
other parts frequently removed. The AMS the aircraft Structural Repair Manual. Always
should be proficient in inspection and repair of refer to these tables for replacement sizes.
203
Drill Selection Chart

Jo - Bolt Column 1 Column II
Nominal Diameter Drill Size Drill Size
5/32 No. 42 (0.089) No. 23 (0.154)

(0.0935 ) 5/32 (0.1562)
3/16 No. 35 (0.110 inch) No. 12 (0.189 inch)
1/4 No. 24 (0.152 inch) D (0.246 inch)
5/16 No. 17 (0.173) M (0.295)
3/8 No. 5 (0.2055) 23/64 (0.3594)
STEP 1 STEP II
SELECT CORRECT PILOT DRILL FROM COLUMN 1 OF THE DRILL SELECT CORRECT FOLLOW UP DRILL FROM COLUMN II OF
SELECTION CHART, THEN DRILL BELOW THE HEAD – THE DRILL SELECTION CHART, THEN DRILL TO THE
SHANK JUNCTION OF THE NUT. PILOT HOLE DEPTH .
STEP III
USE A HAMMER AND NOMINAL SIZE PUNCH TO DRIVE OUT
THE SHANK AND BLIND HEAD.
( A ) TIGHT FASTENER
STEP 1 STEP II
PREVENT NUT FROM TURNING BY ENGAGING SELECT DRILL , IN ACCORDANCE WITH COLUMN 1 OF THE STEP III
DRIVING TOOL NOSE ADAPTER ; HOLDING THE DRILL SELECTION CHART, THEN DRILL THROUGH THE
NOSE ADAPTER WITH VISE - GRIP PLIERS. SHANK , SEVERING THE BOLTHEAD . PICK THE NUT FROM THE HOLE WITH A PUNCH .
( B ) LOOSE FASTENER
AM.300
Figure 7-49. - JoBolt removal.
i
204
Grommet selection is determined as follows: The following repair methods apply to the
1. In the 4002 series, the grommet is used in 4002 series Camloc fastener.
combination with the stud assembly , but is
dependent upon the type of hole required , the Stud Damage
total thickness of the material, and the specified
counterbore of the snapring. Stud assemblies 4002-1 through -15 are re
2. In the 2700 series, the spring cup of the moved by compressing the spring with Camloc
stud assembly eliminates the use of a grommet. pliers and lifting out the stud. To install a new
3. In the 40551 series, the grommet is a stud, compress the spring and insert the stud
nonremovable part of the stud assembly . into the grommet . (See fig. 7-50. ) When the
NOTE : Lateral movement of the grommet spring is released , the stud assembly cannot fall
must be held to a minimum . Vertical movement out .
of the grommet , when the fastener is unlocked, Stud assemblies -16 and longer are retained in
should be held to a minimum to prevent possible the grommet by a split washer. No pliers are
loss or fallout of the grommet. required for removal or installation of these
AM.382
Figure 7-50.- Installing Camloc stud.
205
snapring, using snapring tool T26 , as shown in

figure 7-51 . The snapring must be fully seated
behind the shoulder of the grommet.
Receptacle Damage
Remove the attaching rivets, using standard
removal procedures, in replacing the damaged
receptacle. The new receptacle, which should be
identical to the original, is then riveted into
place.
DZUS FASTENER REPAIR
Dzus fasteners are of two types , the light-duty

type and the heavy -duty type . The main dif
ference in repairing is that the heavy -duty type
requires an additional operation , as the retaining
grommet must also be removed and replaced.
The S shaped spring is replaced if damaged or
broken .
Installation
The light-duty Dzus fastener is installed in

three steps. (See (A) fig. 7-52 . ) The hole is
dimpled, using a special set of dies. The correct
size of stud is then inserted in the dimpled hole .
Using another set of dies, the dimpled material is
then forced into the undercut of the stud , which
locks the stud in place.
The heavy -duty Dzus fastener is installed in
four steps . (See ( B) fig . 7-52. ) A hole is drilled
AM.383 to the proper size, and the grommet is inserted.
Figure 7-51. - Installing snapring behind shoulder of The grommet is then set (partially flared ). The
grommet. correct size of fastener is then inserted through
the grommet. Using a set of dies , the grommet
studs. The stud is inserted in the grommet , and material is flared , forcing the grommet to clinch
the split washer is placed on the stud shank the undercut part of the stud and the panel. This
between the cross pin and the spring cup . The clinching action locks the stud in position.
stud cross pin should not be removed under any
circumstances. Removal
Grommet Damage The light-duty Dzus fastener may be removed

by placing the stud over a hole in an anvil and
Remove the grommet by first prying off the striking it with a hammer and drift punch. After
snapring and slip the grommet out of the hole . the broken stud is driven out , the hole will be
>
Check for possible damage to the hole size , the too large and will be dimpled on the wrong side .
dimple, or countersink , and for correct This may be remedied by flattening the hole
dimensions. Remove all burrs and install a new area with a hammer and redimpling with the
grommet identical to the original. Install a new proper size dimpling tool. Removal of the
206
DIMPLING DIES CLINCHING

DIES
zoom
STEP 1 STEP 2 STEP 3
DRILL & DIMPLE INSERT FASTENER CLINCH
( A ) LIGHT - DUTY FASTENER
SETTING DIES CLINCHING DIES
NILI
STEP 1 STEP 2 STEP 3 STEP 4
DRILL & INSERT GROMMET SET GROMMET INSERT FASTENER CLINCH
( B ) HEAVY - DUTY FASTENER
AM.384
Figure 7-52. -Dzus fastener installation .
heavy -duty Dzus fastener requires a different in the lap patch.

procedure, as a grommet is used in the hole and
must be cut away before the damaged stud can Repair of a Spring
be removed . Insertion of a new grommet is
necessary before installing a new stud . When a spring is broken or damaged , replace
The heavy -duty Dzus fastener may be re with an identical spring. Different spring heights
moved by cutting away the grommet, using are available for each fastener. There are also
diagonal cutter type pliers. The old fastener is special springs which are used for installation in
then free to fall out of the hole . Inspect the hole box corners and panels which would be
area for damage , and repair as necessary. The subjected to either horizontal or vertical move
new fastener and grommet are then reinstalled in ments .
the original hole,> as described earlier.
AIRLOC FASTENER REPAIR
Repair of the Hole The Airloc assembly consists of the recep

tacle, stud, and cross pin as seen in figure 6-10
When the hole is too badly worn to permit (ch . 6 ). The repair of this fastener is normally
reinstallation of the same sized heavy -duty made by complete replacement of the damaged
fastener, it is recommended that a lap patch be parts. The stud and cross pin should never be
installed over the old hole and a new hole cut in reused due to the press fit, which is necessary
the lap patch . The new fastener is then installed for cross pin retention.
207
c
y
e
h
t
f
AM.386
Figure 7-54 . - Inserting cross pin, using special
Airloc handtool .
AM.385 add the thickness of the inner structure and

Figure 7-53 . - Airloc stud head shapes, outer panels, doors, gaskets, reinforcements,
>
countersunk and round .
etc. , in thousandths of an inch . Add to this,
0.010 inch to allow for wrinkling and warpage
Installation Procedures of materials. Select the nearest even 0.010 inch
above the total , for the proper length of stud .
The Navy normally uses Nos. 2 , 5 , and 7 NOTE : When using a floating type receptacle,
Airloc receptacles. Each receptacle is held in add to the preceding measurements 0.020 inch
place by rivets. The No. 2 receptacle is installed for No. 2 receptacles or 0.030 for Nos . 5 and 7
using 3 /32 -inch rivets; No. 5 uses 1 /8- or receptacles.
3 /32-inch rivets; and the No. 7 uses 1 / 8 -inch After determining the correct length of stud,
rivets. Receptacles with flat rivet holes may be insert the new stud into the panel or sheet.
replaced by a receptacle with countersunk holes. Using the special Airloc tool , press the cross pin
The stud normally comes in two head types, into the stud hole , as shown in figure 7-54 .
the countersunk and round head. (See fig . 7-53 .) When Airloc fasteners do not fasten properly
If round head studs are not available, the outer and the studs are known to be the correct
sheet may be dimpled and the countersunk head length , excess misalignment is normally the
stud substituted . The head of the stud is cause. This condition can often be corrected by
stamped to indicate the total grip length. The removing the panel and fastening the studs in a
length of studs is available in varying increments different sequence . Fastening the difficult studs
of ten -thousandths of an inch . first, or by starting in the middle of the panel
To select the proper stud, the AMS must and working toward each end , usually corrects
determine the total grip length . To obtain this, this condition .
208
Removal
Removal of damaged receptacles is ac

complished by removing the rivets, using stand
ard removal procedures . The stud is removed by
pressing out or clipping off the cross pin . The
cross pins for 1 -inch and 1 3 /8-inch studs are
normally removed by pressing out, using special
hand pliers. (See fig. 7-55 . ) The cross pin for
3 /4 -inch studs may be removed either by using
the hand pliers or by clipping off the cross pin.
AM.387
Figure 7-55.-Hand pliers for removing
cross pins.
209
CHAPTER 8
AIRFRAME MAINTENANCE
This chapter is essentially a continuation of studying the following NavPers manuals : Fluid
chapter 7. While chapter 7 dealt mostly with the Power, NavPers 16193-B, and Basic Electricity,
repair of damage to the structural parts of the NavPers 10086 - B .
airframe, this chapter deals with the main
tenance of nonstructural airframe components. TYPICAL SYSTEM DESCRIPTION
In the area of nonstructural airframe com
ponents, the AMS is responsible for such tasks as Typical among simple, unboosted flight
removal, installation , and balancing of flight control systems is the primary flight control
control surfaces; removal and installation of system incorporated in the T -28. The flight
detachable aft fuselage sections, and replace control surfaces (ailerons, elevators, and rudder)
ment of glass and plastic enclosure components. are actuated through a series of push-pull rods,
cables, bellcranks, sectors , and idlers. Figure 8-1
schematically illustrates the elevator portion of
FLIGHT CONTROL SYSTEMS the T -28 flight control system .
The elevators are operated by a fore -and - aft
Flight control systems require little routine movement of the control stick . Raising the
maintenance other than inspection and lubrica elevators causes the aircraft to climb ; lowering
tion . However, it is very important that these be the elevators causes it to dive or descend. The
performed as carefully and conscientiously as elevators are raised by pulling back on the stick,
possible . An inoperative or malfunctioning flight and they are lowered by pushing the stick
control system can result in aborted flight or forward.
total loss of aircraft, cargo , and crew. As can be seen in figure 8-1 , each control
A flight control system includes all the stick is mounted in such a way that it can pivot
components required to control the aircraft backwards and forwards on its mounting pin.
about each of the three axes affecting flight (ch. The front and rear sticks are connected to each
4). A simple flight control system may be all .
other by a push-pull rod attached to their lower
mechanical; that is, operated entirely through ends. A second push -pull rod is attached to the
mechanical linkage and cables from the pilot to lower end of the aft stick . Then , as either stick is
the control surface . Other more sophisticated moved longitudinally the other stick moves in
flight control systems may utilize electrical or the same direction and an equal distance , and
hydraulic power to provide some or all of the the elevators are deflected proportionately. Built
“muscle " in the system . Still others combine into the bracket supporting the rear stick are
some of the features of all three types of adjustable stops which limit the fore -and -aft
systems . The emphasis in this chapter is on movement of the sticks and prevent over
mechanical systems ; however, the AMS should controlling the elevators (see inset).
be familiar with the hydraulic and electrical The push -pull tube (rod ) that connects to the
components as well. A basic knowledge of lowest point of the aft control stick extends aft
hydraulics and electricity may be attained by to the bellcrank . Notice that the function of the
210
Chapter 8 - AIRFRAME MAINTENANCE
12
-16 13 7
-14 10
-15 -14
sic
15 115
9
6 10
18
ber -17
5 2
4
20
19
10
5 JO
AM.432
1. Aft control stick . 11 . Aft sector.
2. Stop bolts. 12. Elevator fitting assembly.
3. Push- pull tube adjustment. 13. Rigging dimension.
4. Bellcrank. 14. Vertical reference line.
5. Rig pins 15. Centerline - stick neutral.
6. Bungee. 16 . Stick throw limit- UP elevator.
7. Forward sector. 17 . Stick throw limit- DOWN elevator.
8. Bobweight. Stick throw range-elevator control.
18.
9. Turnbuckles. Locating angle - vertical reference line.
19.
10. Push -pull tubes. 20. Longitudinal reference line (cockpit floor ).
Figure 8-1 . -Typical elevator flight control system .
bellcrank is to change the direction of the bungee. The bungee is spring-loaded to the
push-pull action from fore-and -aft to up-and center position and regardless of the direction of
down. The second push -pull tube connects the deflection of the elevators, the bungee will assist
forward cable sector and the bellcrank and in returning the system to neutral .
causes the sector to rotate in accordance with From the forward sector , the cables extend
9
the stick movements . back through the aircraft to the aft cable sector.
The forward cable sector pictured in figure Notice in the drawing , just aft of the cable
8-1 incorporates a bobweight which partially turnbuckles, a zigzag line breaking both of the
compensates the system for the weight of the cables . This is a draftsman's symbol used to
elevators. As the sector moves the bobweight up indicate that the cables are really proportionate
or down , the elevators move in the opposite ly longer than is shown here but that they have
direction . The elevator cables are attached to the been reduced in length so that the remaining
forward edges of the sector. Also on the forward essential components of the elevator control
sector is an arm which connects to a centering system may all be shown in the one drawing.
211
NEUTRAL
STICK LEFT LEGEND

HYDRAULIC PRESSURE
RETURN PRESSURE
PIVOT POINT
LEFT HAND RIGHT HAND
CONTROL CABLE CONTROL CABLE
POWER MECHANISM
CABLE SECTOR
POWER MECHANISM
CONTROL VALVES NEUTRAL
UTIUTY
HYDRAULIC
SYSTEM
FLIGHT
CONTROL
HYDRAULIC LOAD FEEL BUNGEE
SYSTEM
NEUTRAL
POWER MECHANISM
LEFT AILERON (UPI DISCONNECT
NEUTRAL
POWER MECHANISM CYLINDER
į NEUTRAL RIGHT AILERON (DOWO
AM. 1048
Figure 8-2. -Aileron control system .
The aft sector is essentially the same as the down .

forward sector and acts as a slave to the forward The A - 4 aileron control system illustrated in
sector. Cables from the forward sector attach to figure 8-2 is typical of a power boost system .
the aft edges of the aft sector. A push -pull tube This system is equipped with a power
from the aft sector extends to, and connects mechanism which provides hydraulic power to
with , the elevator fitting assembly . operate the ailerons. However, in the event of
The elevator fitting assembly, commonly hydraulic power failure, the mechanism can be
called the elevator " horn ,” is built onto the disconnected, placing the system in complete
elevators and extends outward ( usually down manual operation .
ward) from the elevator surface at right angles to Operation of the system is initiated when the
the plane of rotation and the chord line of the control stick in the cockpit is moved to the left
elevator surfaces. As the fitting assembly is or to the right. When the stick is moved, cables
moved fore or aft, the elevators are moved up or
> connected to the bellcrank in the control stick
212
Chapter 8 -AIRFRAME MAINTENANCE
housing are moved to actuate the sector on the cable is corroded , relieve the tension on the
power mechanism . With the actuation of the cable and carefully untwist the cable to visually
sector, the power mechanism operates, trans inspect the interior. Any corrosion on the
ferring the movement to the mechanical linkage interior strands of the cable constitutes failure
which in turn actuates the ailerons. and the cable must be replaced. If no internal
corrosion is detected , remove loose external rust
CONTROL SYSTEM MAINTENANCE and corrosion with a clean dry rag or fiber brush
and apply the specified preservative compound.
Control system maintenance includes inspec
tion to discover actual and potential defects,
servicing with lubricants as required, and the A CABLE WITH BROKEN
correction of reported malfunctions and defects. WIRES DISTRIBUTED NOT
OVER 6 IN I - INCH DIS
Malfunctions which occur in control systems TANCE IS STILL HES
include frayed and loosened cables, worn and SERVICEABLE 3 INC
loosened bearings, unnatural tightness (binding),

and broken or damaged components .
THESE WIRES
ARE BROKEN
Cable Maintenance
THIS IS A 7X19 CONTROL
Cable type control systems require more CABLE MADE OF 6 STRANDS
AROUND I CENTER STRAND.
maintenance than rigid linkage type systems and EACH OF 7 STRANDS HAS
19 WIRES MAKING 7 X 19 OR
must therefore be inspected more thoroughly. 133 WIRES IN ALL .
Cables must be kept clean at all times and must A CABLE WITH MORE THAN 6
be inspected periodically for broken wires, WIRES BROKEN WITHIN A I - INCH
DISTANCE MUST BE REPLACED
corrosion , kinking, and excessive wear.
Broken wires are most apt to occur in lengths
of cable which pass over pulleys or through
fairleads. Tests have proved that control cables
may have broken wires and still be capable of AM,433
carrying their designated load. However, on Figure 8-3 . - Determining serviceable cable.
certain periodic inspections, cables are checked
for broken wires by passing a cloth along the
length of the cable without removing the pre
servative . Where the cloth snags along the cable
is an indication of one or more broken wires.
The bare hands should never be used in checking
for broken wires.
Any 7 x 19 cable that shows more than 6 WIRE NIPPERS
broken wires in any 1 -inch length , or any 7 x 7
cable that shows more than 3 broken wires in ME
any 1 inch , must be replaced. A maximum of 3

broken wires per inch is allowable in the length PLACE CABLE
of cables passing over pulleys, drums, or through PERPENDICULAR
TO CUTTING JAWS
fairleads. Figure 8-3 illustrates how to determine AS SHOWN
a serviceable cable .
Corrosion, kinking, and excessive wear should
be given particular attention during cable
inspection . If found to be kinked or badly worn,
the cable should be replaced, even though the
number of broken wires is less than that AM.434
specified for replacement. If the surface of the Figure 8-4 . - Cutting small cable with wire nippers.
213
CUTTING JAWS
e
r
a
MAXIMUM
40.
CUTTING 7
DIAMETER ‫ یر‬:
3/32"5/32" 7/32"
AM.435
Figure 8-5 . - Cable cutting machine.
NOTE : Do not use metal wool or solvents to cable assembly . This may be accomplished by
clean installed cable as use of metal wool will measuring the old cable assembly , or from
embed tiny dissimilar metal particles, thus measurements provided in the Maintenance
creating further corrosion problems ; and the use Instructions Manual for the aircraft concerned .
of solvents will remove the internal cable Cutting of cables may be accomplished by
lubricant, allowing the cable strands to abrade any convenient method except an oxyacetylene
and further corrode. cutting torch . The method of cutting usually
When a cable is found to be unserviceable and depends upon the tools and machines available.
a spare cable is not available , an exact duplicate If a cable tends to unravel, the ends may be
of the damaged cable may be prepared . This will sweat -soldered, or wrapped with a strip of tape
involve cutting a length of cable to the proper prior to cutting.
length , attaching the necessary end fittings, and Small diameter cable may be cut satisfactorily
· testing the assembly . with a pair of heavy duty diagonal cutters, side
In determining the proper length to which the cutters, or a pair of wire nippers similar to those
new cable will be cut , it is first necessary to shown in figure 8-4. Best results are obtained if
determine the overall length of the finished the cutting jaws are held perpendicular to the
214
cable during the cutting operation . Cables up to

3/32 inch in diameter may be cut in one
operation by this method . Larger cables may
require two or more cuts. When cutting large
diameter cables in this manner, use the end of
the cutting blade and cut only a few strands at a
time.
The most satisfactory method of cutting As @ Core
cables is with a cable -cutting machine having
special jaws to accommodate various sizes of
cable. (See fig. 8-5 .) To use this machine,
position the cable in the proper diameter groove
and hold the cable firmly within 2 inches of the
cutting blades . Hold the cable at right angles to
the cutting blades and pull the operating handle
down sharply . no
A cold chisel used in conjunction with a soft
metal block may also be used for cutting cables.
This method should be used only as a last resort MECHANICAL
because of the way the cable ends will be frayed. TYPE
Figure 8-6 illustrates this method of cutting a
cable. The chisel should be held straight up, with
the cutting blade at right angles to the cable.
Using a heavy hammer, strike the chisel with a
FW
D
-SLOT FOR
INDEX FINGER
COLD CHISEL RE
AR
SOFT METAL
BLOCK
HOLD CHISEL BLADE INLET AIR

PERPENDICULAR TO SUPPLY LINE
CABLE
FOOT VALVE
SHUT- OFF
VALVE
PNEUMATIC
TYPE
AM.437
AM.436 Figure 8-7 . -Hand -swaging tools - mechanical and
Figure 8-6 . - Cutting cable with a cold chisel . pneumatic.
215
nard , sharp blow in order to get a clean , square clean and that all strands remain in a compact
cut . group as shown in figure 8-8. Place a drop or
After the cable is cut, the next step in making two of light lubricating oil on the cable end,
up an aircraft cable is attachment of the then insert the end into the terminal to a depth
terminals. Most terminal fittings are SWAGED of about 1 inch . Bend the cable toward the
onto the ends of control system cables. Swaging terminal, straighten it back to the normal
s essentially a squeezing process in which the position , then push the cable all the way into
cable is inserted into the barrel of the terminal, the terminal barrel. This bending process puts a
then by great pressure applied by dies in a kink in the cable end, which provides enough
swaging machine, the barrel of the terminal is friction to hold the terminal in place until the
compressed or shrunk in diameter so that it swaging operation is completed . It also tends to
clasps tightly around the cable, and the metal of separate and spread the strands inside the
the inside walls of the barrel is molded and cold terminal barrel, thus reducing the strains caused
lowed by force into the crevises of the cable. by swaging.
Figure 8-7 illustrates two types of hand -swaging Both of the hand-swaging tools shown in
ools. The one in the upper part of the illustra figure 8-7 are widely used by naval aircraft
ion is mechanically operated, while the lower maintenance activities. The procedure for using
one is pneumatically operated. both types is described in the following para
When preparing to swage a terminal, cut the graphs.
able to the required length, allowing for the When operating the mechanical type , the
elongation ( increase in length due to stretching) AMS places the proper size pair of dies on the
of the fitting which will occur during the swaging tool . The terminal is then located in the
swaging process. The amount of elongation will jaws of the tool as shown in figure 8-9 , and the
vary with the type and size fitting used. There swaging operation is performed . As the dies
ore, the elongation must be taken into account rotate in such a manner as to pull the terminal
whenever making up any cable. Tables are from right to left, the dies compress the terminal
>
urnished in the publication NavAir 01-1A - 8 , barrel onto the cable and swaging occurs . Rota
Aircraft Structural Hardware, or superseding tion of the dies is accomplished by opening and
publication , which provides elongation data for closing the handles in the manner of a pair of
ill types and sizes of fittings. scissors.
Make sure that the cable end is cut square and After completion of swaging and removal of
the fitting from the swaging tool , measure the
outside diameter of the shank with a micrometer
or with the gage furnished with the swaging
SQUARE-CUT CABLE END
outfit to determine whether or not the terminal
has been swaged sufficiently . This may be
determined by checking the measurement with
the applicable cable terminal table in NavAir
01-1A-8 .
The pneumatic swaging tool shown in figure
8-7 is a lightweight portable unit designed to
precision swage the metal of a terminal into the
interstices (crevices) of the cable strands. The
-SWAGE TYPE CABLE swager may be mounted on a base plate and
TERMINAL BARREL
used on a bench , or it can be taken to the job.
When the swaging tool is taken to the location
of the job , it may be held in the hand at the
balance point or cradled in the arm while using.
The pneumatic swaging kit has several dif
AM.438 ferent sizes and types of dies used for swaging
Figure 8-8 . - Inserting cable in swage -type terminal. ball and sleeve type terminals and for cutting
216
The following step -by -step procedure is

recommended for setting up the pneumatic
swaging tool :
1. Connect the air supply to the foot valve.

For efficient operation use an inlet air line with
at least 3/8 inch inside diameter and 90 pounds
minimum line pressure.
2. Connect the swager air line to the foot
valve .
3. Clean the dies, remove any steel particles
which may have adhered to the die cavity , and
apply a light film of oil to the entire die .
4. Insert the dies in the swaging tool as
previously described .
CAUTION : Do not insert or remove dies until
the air supply which is connected to the swager
is shut off.
MECHANICAL TYPE With the pneumatic tool set up for use, the
following steps should be followed while
swaging terminals to cables.
1. Position the terminal on the cable, using

the old cable as a pattern , or follow the
instructions given in the applicable technical
directives. When using a ball type terminal, a
minimum 1 1/2 inches of cable must extend
beyond the ball to allow room for holding and
turning the terminal during swaging. The excess
is trimmed, if necessary , after the swaging
operation . When using MS 20667 terminals, 1/4
inch of cable must extend through the terminal.
On all other terminals, the cable is bottomed
(inserted all of the way into the terminal).
2. Each terminal is cleaned, using a suitable
PNEUMATIC TYPE solvent, then coated with a light oil.
3. With the terminals positioned in the cavity
of the forward die , slide the rear die to its
AM.439 forward position using the slot provided in the
Figure 8-9. -Locating the terminal in the swaging yoke for the index finger.
tools. NOTE : To prevent damage to terminal or
cable during the swaging cycle, maintain light
and trimming cable. Like the mechanical pressure on the cable towards the front of the
swaging tool, the dies come in matched sets, and swager. This holds the terminal and cable firmly
must be used together. The dies are installed by in the forward die cavity .
inserting either die through the yoke opening, 4. Depress the foot valve firmly and rotate
into the die cavity with the keyway down and the cable back - and- forth in 180 -degree arcs or
the shank facing to the rear of the swager. Slide complete revolutions. The length of time the
the first die back in order to clear the opening foot valve is held depends upon the type and
for the insertion of the mating die. The second size of fitting being swaged. This time can be
die is inserted with the shank facing forward . found by referring to the chart supplied with the
217
pneumatic swaging tool . If the terminal will not correct length of the new tube is obtained by
rotate , stop swaging immediately, rotate the loosening the checknut and turning the end
terminal 90 degrees, and start swaging again. fitting in or out, as necessary . When the push
5. Release the foot pedal to stop swaging, pull tube has been adjusted to its correct length ,
and remove the terminal from the swaging tool the checknut must be tightened against the
for inspection. If the diameter is oversize or the shoulder of the end fitting. Normally, only one
terminal surface is too rough , repeat the opera end of a push -pull rod is adjustable. The
tion . adjustable end has a hole (witness hole ) drilled
If swaged terminals are to be used on both in the rod , located at the maximum distance the
>
ends of the cable , recheck the overall length of base of the end fitting is allowed to be extended.
the cable and trim , if necessary , prior to If the threads of the end fitting can be seen
installing the second terminal. Make certain that through this hole , the end fitting is within safe
all additional fittings and accessories , such as limits.
cable stops and fairleads, are slipped onto the When attaching push - pull tubes with ball
cable in the proper sequence . The other terminal bearing end fittings, the attaching bolt and nut
may then be swaged , using the same procedure must tightly clamp the inner race of the bearing
as that used for the first one . to the bellcrank , idler arm , or other supporting
All newly fabricated cables should be tested structure . A nut and bolt only finger tight does
for proper strength before they are installed in not utilize the bearing for the purpose it was
aircraft. The test consists of applying a specified intended . Therefore, nuts should be tightened to
tension load on the cable for a specified number the torque values listed in the aircraft Main
of minutes. The proof loads for testing various tenance Instructions Manual.
size cables are given in tables contained in After installing a new push-pull tube in a
NavAir 01-1A-8 , or subsequent publications. flight control system , the control surface must
Proof loading will result in a certain amount of be checked for correct travel. Procedures for
permanent stretch imparted to the cable. This accomplishing this are described later in this
stretch must be taken into account when chapter. If travel is incorrect, the length of the
fabricating cable assemblies. Cables which are push -pull tube must be readjusted .
made up slightly long may be entirely too long
after proof loading.
Replacing of cables in the aircraft, especially Troubleshooting
those routed through inaccessible spaces, can be
difficult. One method used is to secure a snaking When the cause and remedy for a reported
line to the cable to be replaced , remove the malfunction in a control system are not im
pulleys from the brackets, and pull out the old mediately obvious to the AMS it may be
cable , pulling the snaking line into the cable necessary to troubleshoot the system . Most
system run at the same time. Attach the new aircraft Maintenance Instructions Manuals
cable assembly to the snaking line and pull the provide troubleshooting charts which list some
snaking line out to pull the new assembly into of the more common malfunctions likely to
place. Replace the pulleys and attach the new occur in the system . Each discrepancy is ac
cable in the system . companied by one or more probable causes and
a remedy is prescribed for each cause . The
Push -Pull Linkage Maintenance troubleshooting charts are organized in a
definite sequence under each possible trouble,
Push -pull tube linkage must be inspected according to the probability of failure and ease
closely for dents and cracks and for bent lengths of investigation . In order to obtain maximum
of tubing. Damaged tubes may have to be value from these charts, they should be used
replaced. End fittings are checked for damage systematically in accordance with the aircraft
and for wear and security of attachment. Worn manufacturer's recommendations. A portion of
or loose fittings must be replaced. the troubleshooting chart for the control system
When replacing a damaged push -pull tube , the illustrated in figure 8-1 is shown in table 8-1 . Home
218
Table 8-1. - Troubleshooting flight control system .
Trouble Probable Remedy

cause
Cockpit controls hard to move . Control system not rigged Rerig control system .
correctly.
Control cable tension too Check tension with tensio
high. meter .
Equipment or structure Check routing of linkages

interfering with move and cables , correct as
ment of control system . necessary
Control cable fouled on Check vicinity of turn

equipment. buckles .
Control cables incorrectly Reroute control cables .

routed .
Pulley out of alignment. Straighten or replace

pulley bracket .
Defective or dry bearing Clean and lubricate bearing
in the system . or replace if damaged .
Defective bungee in Adjust bungee . Replace
system . if necessary .
Sectors torqued too high . Isolate sector and torque to

proper value or replace
if defective .
Cockpit controls will not move Rig pin left in system dur Remove rig pin .
with the surface controls dis ing rigging procedure.
connected .
Bungee jammed . Remove and repair , or
replace .
Foreign object jammed Remove foreign object and
into system . inspect system for damage.
Quadrant bolt torque too Torque bolt to specified
high . torque as per Maintenance
Instructions Manual.
Control surfaces will not move . Attaching bolts overtorqued . Torque correctly .
Movable surface striking Replace or repair movable
or binding on fixed sur surface as required . Re
face . Hinge pin bent or place or align .
misaligned .
219
Since most present day aircraft incorporate control system is to insure neutral alignment of
some form of electrical control and/ or hydraulic all connecting components and to regulate and
boost in their flight control systems , main limit the surface deflection in both directions. In
tenance of these systems must include the the elevator system illustrated in figure 8-1 ,
related electrical circuits and hydraulic systems rigging begins at the aft sector.
in many instances . Although an AE or AMH is The aircraft manufacturer has determined the
generally called upon to locate and correct position of the aft sector when it is in the
electrical or hydraulic troubles, respectively, the neutral position . He has furnished a rig pin hole
AMS should be able to check circuits for loose in the sector and a mating hole in the adjoining
connections , perform continuity checks if structure. (See ( 5) in fig. 8-1 at aft sector .) With
necessary , and perform minor troubleshooting the rig pin inserted in the aft sector and in the
of the hydraulic system. A knowledge of aircraft structure the sector is held firmly in the
electrical and hydraulic symbols and the ability neutral position . With the sector in this position,
to read electrical circuit diagrams and hydraulic the push -pull tube connecting the sector with
system schematics are necessary ; therefore , the the elevator fitting assembly is adjusted to
AMS should study the training manuals Basic position the elevators to the neutral ( stream
Electricity and Fluid Power. lined) position. The neutral position is deter
Loose electrical connectors are located by mined by use of an elevator rigging fixture
checking all those in the circuit . A connector illustrated in figure 8-10. The curved section of
that can be turned by hand is loose and should the rigging fixture is graduated in degrees on
be tightened handtight. either side of the neutral (zero degree ) position
A continuity check is simply a matter of which is about midway of the curved part of the
determining whether or not the circuit to the rigging fixture .
applicable unit is complete. The check for The rigging fixture is fastened securely to the
continuity may be made with a test lamp , which aircraft at indicated points of attachment. When
can be drawn from supply. properly mounted , the index marks ( gradua
To perform an electrical continuity check , the tions) on the curved section align with the
connector at the electrically controlled unit is elevators and indicate the position , in degrees, of
first disconnected . Then , with all necessary
switches and circuit breakers closed , the test
lamp is connected into the circuit at the
electrical connector. The lamp thus indicates
OR
whether or not the circuit is complete.
pon
T
E VA
Continuity checks may also be made with the
own
EL
use of a multimeter. A multimeter is an instru
ment used for measuring resistance, voltage , or R
amperage . Using this instrument is primarily the IZE
IL
responsibility of the AE ; however, the AMS may AB E
ST FAC
R od
learn to use it by referring to Basic Electricity, S U owo
- co
NavPers 10086-B, Chapter 15. Remember,
certain portions of this training manual are
recommended supplemental reading for all AMS
personnel .
Satisfactory background information on
hydraulic theory may be acquired by referring

to the training manual , Fluid Power , NavPers
16193 ( Series ).
Rigging and Adjustment

AM.390
The purpose of rigging and adjusting a flight Figure 8-10 . - Elevator rigging fixture .
220
the elevators at any time. If, with the aft sector

> As mentioned in chapter 6 , only two methods of
rig pin in place, the elevators are not in neutral ; safetying turnbuckles have been adopted as
for example, 5 degrees above the neutral mark , standard procedures by the armed services — the
lengthening the push -pull rod end will push the clip -locking ( preferred ) method and the wire
elevator fitting assembly forward and thereby wrapping method .
lower the elevators . If the elevators are too low , CLIP -LOCKING TURNBUCKLES . - The clip
then shortening the rod will bring them up as locking method of safetying uses an NAS lock
required . clip. To safety the turnbuckle, align the slot in
The next step in rigging and adjusting is the the barrel with the slot in the cable terminal.
adjusting and tightening of the pair of cables in Hold the lock clip between the thumb and
the system . This is accomplished by tightening fore-finger at the end loop. Insert the straight
the turnbuckles on each cable evenly until the end of the clip into the aperture formed by the
required tension is obtained . During cable aligned slots. Bring the hook end of the lock clip
tightening the rig pin is retained in the aft over the hole in the center of the turnbuckle
sector, leaving the forward sector free to turn. barrel and seat the hook loop into the hole.
Therefore, when the necessary tension is Application of pressure to the hook shoulder at
recorded on one cable , that is also the tension the hole will engage the hook lip in the
on the other cable. To insure that the cables turnbuckle barrel and complete the safety lock
were tightened evenly , check the forward sector ing of one end. The above steps are then
rig pin hole to see if the rig pin can be inserted repeated on the opposite end of the turnbuckle
through the sector and into the structure. If this barrel. Both locking clips may be inserted in the
is not possible, then the cables must be adjusted same turnbuckle barrel hole or they may be
by loosening one and tightening the other the inserted in opposite holes. (See fig. 6-40 in
same amount. This will maintain the correct chapter 6. )
tension on the cables and at the same time Lock clips must be examined after assembly
rotate the forward sector to the neutral position. for proper engagement of the hook lip in the
The cable section is properly rigged when it is turnbuckle barrel hole by the application of
possible to insert and remove the forward sector slight pressure in the disengaging direction . Lock
rig pin easily with the aft sector pin installed and clips must not be reused, as removal of the clips
the cables tightened to the prescribed tension . from the installed position will severely damage
Figure 8-11 illustrates a tool for holding the them.
terminals on cable ends to prevent their rotation WIRE -WRAPPING OF TURNBUCKLES.
while adjusting the turnbuckle barrel. First, two safety wires are passed through the
When all adjusting and rigging on the cables is hole in the center of the turnbuckle barrel, and
completed, safety the turnbuckles as necessary . the ends of the wires are bent 90 degrees toward
the ends of the turnbuckle, as shown in figure
>
6-40,
Next , the ends of the wires are passed through
the holes in the turnbuckle eye or between the
jaws of the turnbuckle fork , as applicable. The
i
wires are then bent toward the center of the

turnbuckle and each one wrapped four times
around the shank, securing the wires in place .
When a swaged turnbuckle terminal is being
safetied, one wire must be passed through the
hole provided for this purpose in the terminal. It
is then looped over the free end of the other
wire and both ends wrapped around the shank,
as shown in figure 6-40.
AM.391 RIGGING AND ADJUSTING RIGID
Figure 8-11 . - Turnbuckle rigging clamp. CONTROLS . - The push -pull tube connecting
221
the forward sector and the bellcrank is adjusted ment the elevators should be held in neutral
to the correct length by installing a rig pin in the (plus or minus the prescribed number of
bellcrank and turning the rod adjustable eye in degrees) by bungee action . If the elevators are
or out until the rod can be installed between the too high , shorten the bungee rod end . If they are
sector and bellcrank without binding. At this too low , lengthen the bungee. With the bungee
point three rig pins are in place and should properly adjusted , tighten the bungee rod end
remain in place until the control sticks are rigged locknut and safety it as required.
to neutral .
When positioning the control sticks to neutral Removal and Installation
the rear stick must be adjusted first as we are
working forward from the elevator surface . The It is sometimes necessary to remove control
push -pull tube connecting the bottom of the surfaces from aircraft for the purpose of repair
rear stick with the bellcrank must be adjusted or replacement. The instructions presented in
until the stick centerline ( 15 , fig. 8-1 ) is the the following paragraphs are general instruc
prescribed number of degrees forward of a tions, applicable to several types of aircraft. For
vertical reference line ( 14). The vertical refer specific instructions and precautions, always
ence line is a position that the centerline of the consult the applicable Maintenance Instructions
control stick would attain at a 90 -degree angle Manual before removing a control surface from
( 19) to the cockpit floor (20), as determined by any aircraft.
a level protractor. REMOVAL . - Removal of a control surface
Adjust the length of the push -pull tube should not be attempted until the aircraft is
between the control sticks to position the front placed in a hangar or other area protecting it
control stick to an angle identical to that of the from the wind . Before any control surface is
aft control stick , and remove all three rig pins. removed from the aircraft, it should be tagged
This completes the rigging and adjusting of the with the bureau number of the aircraft and the
control system to neutral. All that remains is to location of the control surface on the aircraft.
adjust the stops that limit the fore and aft travel The first step is to remove the necessary
of the control sticks and rig and adjust the access opening covers and fairings. To prevent
bungee that holds the system in the neutral the loss of these inspection plates and fairings,
position . they should be left attached to the aircraft by
The stop bolts (2 , fig. 8-1 ) are located, one one screw or by a piece of safety wire. The other
each, in front and behind the aft control stick . screws should be put in a container to prevent
They are installed so that the stick contacts the them from being lost .
stop bolts at the extreme limits of its travel. The Disconnect bonding wires, electrical con
maximum travel of the elevators in each nectors , and control linkage. Before dis
direction is determined by the manufacturer and connecting cable linkage, the tension should be
is controlled by the stop bolts . With the rigging relieved at the most convenient turnbuckle.
fixture still in place , move the control stick all Next , support the entire control surface , either
the way forward and adjust the stop until the manually or with mechanical supports, in such a
elevator DOWN throw conforms to the instruc manner as to remove all the load from the
tions in the applicable Maintenance Instructions hinges. Remove the hinge bolts, using a mallet
Manual. Pull the stick all the way aft and adjust and brass drift pin where necessary . The control
the aft stop bolt to obtain the correct elevator surface should be supported and all the hinges
UP throw. The stop bolts are safety wired in kept in alignment until the last hinge bolt has
place after this adjustment. been removed . On long control surfaces it may
The last item to be adjusted in this control be necessary to replace the hinge bolts with drift
system is the centering bungee. Connect the pins to keep the hinges aligned while removing
bungee and adjust its rod end so that with the the remaining hinge bolts.
stick against the stop bolt in the full down Secondary and auxiliary control surfaces are
elevator position , the bungee is a minimum of sometimes attached with piano wire hinges.
1/32 inch from bottoming . After this adjust Removal of the piano wire can be accomplished
222
by cutting off the bent ends, securing one end of surface correctly supported , install the hinge
the wire in the chuck of a hand drill, and bolts. In the case of a secondary or auxiliary
rotating the wire with the drill while withdraw surface attached by piano hinge wire , a new wire
ing it . Excessive spinning will have a wearing should be used .
effect on the hinge material and should be After a control surface is installed , the control
avoided. The reuse of piano hinge wire is not linkage is then connected and the rigging of the
considered safe, therefore, any wire removed system checked .
should be discarded .
After all the hinges are disconnected, remove Balancing of Flight Control Surfaces
the control surface from the aircraft, supporting
it carefully to prevent damage to the hinge All flight control surfaces are balanced at the
brackets and adjoining surfaces. Replace the time of manufacture by the addition of counter
hinge bolts in the hinges to prevent them from weights inside the leading edge of the control
being lost or damaged . surface. This balance must be maintained
INSTALLATION . - Before installing a control (within certain tolerances) throughout the serv
surface, check the identification tag to deter ice life of the control surface, because flutter or
mine the location on the aircraft. Place the dynamic oscillation of these surfaces in flight is
surface in position carefully , being sure that all sensitive to balance . Balance tolerances are
the hinge holes are properly aligned . Drift pins always specified in the applicable aircraft Struc
may be used to align the holes . With the control tural Repair Manual.
BALANCE STAND
BRACKET
RUDDER TIP
PIN
RUDDER RUDDER HINGE

FITTING
VIEW A
WEIGHTS AND CONTAINER
भाग
BALANCE STAND
HINGE CENTERLINE
keta -X
RUDDER SECTION
AM.392
Figure 8-12 . - Typical balance stand .
223
Following the repair to (or modification of) been +50 to +60 pound/inches, additional
any control surface, a balance check should be counterweights would have been necessary .
made to determine whether the specified toler
ances of the control surface have been exceeded .
This check is made on a specially constructed AFT FUSELAGE SECTION
balance stand similar to the one illustrated in REMOVAL AND INSTALLATION
Figure 8-12 .
When a control surface is mounted on a Most singleengine jet aircraft have the engine
balance stand , a downward movement of the
> incorporated in the fuselage. Access to the
railing edge below the horizontal position engine for removal and installation is provided
ndicates a positive (+) unbalanced moment . An by means of a removable aft section of the
upward movement of the trailing edge above fuselage. All or part of other systems located in
horizontal indicates a negative (-) unbalanced the aft fuselage section are the flight control
moment. surfaces and systems ; landing gear, arresting
Before making a balance check, the control gear, and takeoff assist systems ; personnel
surface must be complete with tab and other environmental systems; hydraulic power
equipment and the final coat of paint already systems ; automatic flight control systems ; and
applied . The area must be free from drafts in electrical power systems and lighting provisions.
order for an accurate check to be made . Strictly speaking, maintenance of aft fuselage
TYPICAL BALANCING PROCEDURE . - The -
sections is limited to installation and removal.
Following procedure is taken from the Structural Should repairs to the airframe become neces
Repair Manual of a typical naval aircraft. sary , such work is effected in accordance with
the applicable aircraft Structural Repair Manual.
1. Mount the control surface on a balance It is a responsibility of the AMS to remove and
tand , using the two outer hinge brackets install aft fuselage sections , which hereafter may
mounts . (See fig . 8-12 . ) also be referred to as the tail section , or merely ,
2. Suspend a container from the leading edge tail .
or trailing edge (as necessary ) and add weight to Many of the functions associated with
he container until the control surface is in a removal and installation of tail sections are
horizontal position . common to nearly all aircraft having a
3. Measure the distance from the point of removable tail . The procedure presented in the
suspension of the container to the control following paragraphs is taken from the Main
surface hinge centerline . This distance is tenance Instructions Manual for the A -4
designated as X. Distances forward of the hinge (Skyhawk ) and is a typical example of the steps
ine are indicated +X, and distances aft of the involved . The preparatory steps are general in
hinge line are indicated-X. nature and apply to all aircraft.
4. Remove the container , and determine the
weight of the container and its contents. This REMOVAL
weight is designated as W.
5. The total weight , W , multiplied by the The first thing to do after being assigned to
listance, X, is equal to the calculated un remove the tail section from an aircraft is to
Dalanced moment . assemble all the special tools and support equip
EXAMPLE : A control surface in a balance ment specified in the applicable Maintenance
stand requires a 7-pound weight (container and Instruction Manual . It is futile to start the job if
contents ), located 6.5 inches forward of the a needed piece of support equipment is un
hinge line to balance the surface in a horizontal available .
position. This indicates an unbalanced moment The second step should be a briefing by the
of +45.5 pound/inches in the control surface. crew leader to the crew (four men are required
The tolerance for this control surface is +40 to on the Skyhawk) on various phases in the
+50 pound/inches ; therefore, no correction is tail-removal sequence and the part each is
necessary . Had the tolerance for this surface expected to accomplish . All of the CAUTION
224
and WARNING notes in the Maintenance hooks. The adapter hook straps are then
Instructions Manual which relate to the job at adjusted to secure the tail section to the adapter.
hand should be read and discussed. At the end The main bolts are now ready to be removed .
of the briefing, the crew leader (regardless of The removal of the main bolts must be
experience) should retain the Maintenance performed in a definite sequence. In addition , as
Instructions Manual containing the steps in the some of the bolts that splice the two parts of the
removal sequence so that he may use the list of fuselage together are removed , bullet- shaped
steps as a checkoff list to make sure no vital step thread protectors are installed on the bolts . The
is overlooked or performed dangerously out of thread protectors are also called aft fuselage
sequence . attachment aligners, since they are also used to
Prior to the actual separation of the tail help align the forward and aft sections of the
section from the main fuselage there are many fuselage during reinstallation of the tail . With
preparatory steps to be taken . These include the thread protectors in place the aft section will
such preparations as the following: not damage the splice bolt threads as the two
fuselage sections are disengaged .
1. Insuring approximately even fuel levels in Before moving the tail the entire work area
external tanks. should be reinspected for proper disengagement
2. Aileron gust lock installed . of all lines, hoses, quick -disconnects, and elec
3. Flaps are raised . trical connections. If all is clear, move the tail
4. All ground handling safety equipment is section , supported by the trailer and installation
installed . adapter, away from the wing and fuselage
5. All external power (hydraulic and forward section .
electrical ) is disconnected .
6. Removal of all necessary access doors and INSTALLATION
panels.
7. Release of air pressure from the arresting Installation of a tail section is essentially the
hook hold -down unit . reverse of the removal procedure . Many of the
preparatory steps have to be rechecked to insure
After completing the preparatory steps listed that the tail can be reinstalled safely. Just prior
in the foregoing, all electrical lines, control to actually mating the two fuselage sections an
cables, hydraulic and pneumatic tubing, oxygen inspection should be made of the interiors of
system lines, and drain lines must be discon each section and all hardware which must be
nected and stowed as per the Maintenance reconnected . Some systems such as the fire
Instructions Manual and each of the applicable detection system should be checked out in both
line ends or tubing openings covered to prevent the forward and aft fuselage sections separately.
contamination while separated . The checking of the fire detection system
In order to remove the tail section from the components makes replacement of damaged
Skyhawk , the tailpipe clamp and tailpipe must components possible before the aft fuselage
be removed next . section is installed .
With the aft fuselage installation adapter Extreme care must be exercised during
properly secured to the installation and removal installation of the tail to prevent damage to
trailer, position the trailer beneath the tail control cables, electrical cables, hydraulic lines,
section . Adjust the height of the installation and the heat radiation shields on the lower sides
adapter, using hoist mechanisms on the trailer; of the engine.
then insert the pin to secure the arresting hook With the aft fuselage installation adapter
attaching fitting. Operate the trailer hoist installed on the installation and removal trailer,
mechanisms to raise the adapter until it contacts and the tail section securely mounted on the
the fuselage aft section firmly at the supporting adapter, move the tail section into position for
points. Adjust the adapter hooks on the installa attachment to the forward fuselage section .
tion adapter to align with the holes in the left During the actual attachment of the aft
and right-hand sides of the fuselage; engage the fuselage section to the forward section, another
225
MAINTENANCE ACTION FORM

OPNAV FORM 4790/40 ( 10-69 ) S/ N.0107.770.4400
1. JOB CONTROL NUMBER 2. TYPE EQUIP . 3. BU / SER NO . 4. ACTION 5. WORK 6. MAINT . LEVEL 7. ACTION DATE
ORG . CENTER
ORG . DATE SER SUF
2 3
AC3 20201033 AACD 150160 AC 3 120 ORG . O INT P 2025

DEP
8. WORK UNIT CODE 9. WHEN DISCO 10. TYPE MAINT. 11. ACTION 12. MAL 13. ITEMS 14. MAN . 15.EMT 16 .
TAKEN PROC . HOURS
20.
11410
REMOVEC TEM
D B
21
s
INSTALLED
800
ITEM
o 4010
.1 MFGR 2 SERIAL NUMBER .1 MFGR .2 SERIAL NO .
13 PART NUMBER .4 TIME / CYCLES . 3 PART NUMBER .4 TIME CYCLES
B. DISCREWCY C. CORRECTIVE ACTION
REMOVE AND REINSTALL REMOVED AND INSTALLED

TAL SECTION FOR TAIL SECTION
POWER PLANTS
D. ENTRIES REQUIRED SIGNATURE E. CORRECTED BY F. INSPECTED BY G. SUPERVISOR

CONFIGURATION YES NO
30 .
LOG
ACCESS RECORD
YES
YES
NO
NO
46 .
8. Bulownisz 1.Hewson B.Bennett
AMSZ
FAILED MATERIAL
AMSC
REPAIR CYCLE DATA
2 .4
ACT
DATE DATE TKN
MAL OTY MFGR PART NUMBER /REF , SYMBOL
1. REMOVED 5. TO AWP
2. RECEIVED 6. OFF AWP

MATL . CONTROL
3. WORK STARTED 7. TO AWP
4. COMPLETED 8. OFF AWP
RF1 B COND R / S 9.
0.
H. PCN PRIORITY DATE DUE
IN OUT
J. K.
ACCUMULATED HOURS REQUIRED MATERIAL
VAT TIME
NAME / SHIFT DATE MAN - HOURS EMT REQ . NO . MFGR PART NUMBER QTY PRI
ORD REC
AWP
TOTAL
AM.5
Figure 8-13 . -MAF documentation for the removal and reinstallation of a tail section .
226
definite sequence is employed . Many of these handled only with clean cotton gloves.
steps require inspection by a Quality Assurance 2. The use of harmful liquids as cleaning
Representative as soon as they are completed . agents should be avoided .
Once the tail section structure is properly 3. Fabrication, repair, installation , and main
>
attached to the forward fuselage, then recon tenance instructions must be closely followed .
nection of all the systems between the aft and 4. Operations which might tend to scratch or
forward sections can be accomplished . Every distort the plastic surface must be avoided. Care
system that can be checked must be checked for must be taken to avoid scratching plastic sur
proper operation after reconnection . Other faces with finger rings or other sharp objects.
systems may require servicing prior to operation .
When the crew has completed their work the Just as woods split and metals crack in areas
Quality Assurance Representative will assure of high , localized stress , plastic materials
himself on final inspection that the work has develop , under similar conditions , small surface
been properly completed . fissures called CRAZING . These tiny cracks are
Figure 8-13 illustrates the use of a single copy approximately perpendicular to the surface, very
Maintenance Action Form (MAF ) for the re narrow in width , and usually not over 0.01 inch
moval of a tail section to facilitate other in depth . These tiny fissures are not only an
maintenance and the reinstallation of the same optical defect, but also a mechanical defect,
tail section . inasmuch as there is a separation or parting of
material .
TRANSPARENT PLASTIC Crazing may be caused by improper cleaning,
ENCLOSURES improper installation , improper machining, or
cold forming. Once a part has been crazed ,
Because of the many uses of plastic materials neither the optical nor mechanical defect can be
in aircraft enclosures , optical quality ( quality removed permanently ; therefore, prevention of
promoting good vision) is of great importance . crazing is most necessary .
These plastic materials are similar to plate glass
in many of their optical characteristics. Ability
to locate and identify other aircraft in flight, to CLEANING PLASTIC SURFACES
land safely at high speeds , to maintain position
in formation , and in some cases, to sight guns For exterior surfaces, flush with plenty of
accurately through plastic enclosures, all depend water, using the bare hand gently to feel and
upon the surface cleanliness, clarity , and dislodge any dirt , sand , or mud. The plastic is
freedom from distortion of the plastic material. then washed with a mild soap, specification
These factors, in turn , depend entirely upon the P - S -560 and clean water. NOTE : Water contain
amount of care exercised in the handling, ing dirt and abrasive materials may scratch the
fabrication , maintenance , and repair of the plastic surface.
material. A clean soft cloth , sponge , or chamois may be
Plastics have many advantages over glass for used to carry the soap and water to the plastic .
aircraft application, particularly the lightness in The cloth, sponge , or chamois should not be
weight and ease of fabrication and repairs ; used for scrubbing ; use the hand method as
however, they lack the surface hardness of glass, described for removing dirt or other foreign
and are very easily scratched , with resulting particles.
impairment of vision . Care must be exercised Dry with a clean damp chamois , a soft clean
while servicing all aircraft to avoid scratching or cloth , or soft tissue by blotting the surface until
otherwise damaging the plastic surface. dry . Rubbing the surface of the plastic will
Specific procedures are described later in this induce (build up) an electrostatic charge that
section for light maintenance ; however, the attracts dust particles to the surface . If the
following general rules should be emphasized : surface does become charged , patting or gently
blotting with a damp , clean cloth will remove
1. Transparent plastic materials should be this charge as well as the dust .
227 .
To clean interior plastic surfaces, dust the to its original thickness when excessive heat is
face lightly with a soft cloth . Do not wipe the applied. The best procedure is to keep either the
face with a dry cloth . Next , wipe carefully wheel or plastic constantly in motion relative to
h a soft damp cloth or sponge . Keep the one another. Keep the pressure against the wheel
th or sponge free from grit by rinsing it to a minimum , and change the direction of
quently in clean water . buffing often .
Cleaning and polishing compound , Specifica Briefly, the procedure for removing scratches
n P- P-560, may be used to remove grease and is as follows:
Apply the compound with a soft cloth, rub A single deep scratch or imperfection is
a circular motion until clean , and polish with reduced by sanding to a number of small,
ther soft cloth . shallow scratches. These scratches, in turn , are
reduced to a larger number of still smaller
scratches on a buffing wheel to which a fine
MOVAL OF SCRATCHES abrasive is applied. These finest scratches are
further reduced or filled in with tallow or wax.
The AMS is required to remove and install A final buffing or polishing brings the surface to
opies, escape hatches , and other aircraft
>
a high gloss . The depth of scratch will determine
uctures that contain plastic sections. Great how many of these operations are necessary.
e must be taken to protect the finish of the However, each step in the process must be
stic . Plastic is very soft as compared to other performed thoroughly, or subsequent polishing
>
craft structural materials. The surface is easily will not remove scratches left by previous
atched or damaged , and should be protected operations.
the use of proper protective covers and It is obvious that sanding and buffing cause
rage racks which are provided by the aircraft thickness variations in the plastic around the
nufacturer or are manufactured locally. It is scratch . If skillfully done , these operations will
ier to avoid scratches than to remove them . It cause only minor optical distortions which will
possible , however , to restore even a badly not be serious in most applications . Distortion
atched surface to a good finish by buffing and may be reduced by gently polishing and feather
netimes sanding. ing a fairly large area around the scratch . In
Aircraft Maintenance Instructions Manuals critical optical sections, however, even minor
cify limits on the length , width , and depth of
> distortions may cause serious deviations in
cks , and in what areas they are allowed . sighting. Such sections, even though scratched,
ese measurements are normally made by the should not be sanded or buffed. If necessary ,
of an optical micrometer. If a scratch these sections are replaced .
ceeds the specified limitations, the surface
st be replaced . Sanding
Before starting to sand or buff, be sure the
stic surface is clean . The buffing wheels and Transparent plastics should never be sanded
mpounds should also be free of dirt and grit unless absolutely necessary , and then only when
avoid seriously scratching the surface during surface scratches, which may impair vision , are
- polishing operation . If the buffing wheels too deep for removal by buffing.
ve been used before, remove any hardened When sanding is necessary , the finest smallest
>
ow by running the wheels against a metal grit abrasive paper that will remove the scratch
ge . or other defect should be used first. Normally ,
It is important to remember that most plastic the AMS will never need abrasive paper coarser
closures are thermoplastic and soften when than No. 320A ; however, abrasive paper as
ted . The friction of sanding or buffing too coarse as No. 240A may be used if the situation
g or too vigorously in one spot can generate warrants . The abrasive paper is wrapped around
ugh heat to soften or burn the surface. Also, a felt -covered , wooden or rubber block and the
stic that has been deep-drawn , or formed to defective area rubbed lightly, using plain water
mpound curvatures, has a tendency to return or water with a 2 percent soap content as a .
228
DO NOT SAND UNLESS ABSOLUTELY NECESSARY TO RE

MOVE DEEP SCRATCHES . HOLD SANDPAPER BY SMOOTH
RUBBER OR WOODEN BLOCK . SAND OVER A WIDE AREA
TO PREVENT OPTICAL DISTORTIONS . EXCESS PRESSURE
IN SANDING OR BUFFING WILL BURN PLASTIC .
SCRATCH
0 ALWAYS WET PAPER
SAND WITH
ROTATING
MOTION
RIGHT WRONG
AM.393
Figure 8-14 . -Proper method of sanding plastic.
lubricant. Use circular strokes as shown in figure sequence : Nos. 400A, 500A, and 600A. Wash
8-14. Never use a straight back -and- forth the plastic after each operation. During each
motion . Sand an area about two or three times step , the deeper scratches left by the preceding
the length of the defect in order to minimize grade of abrasive should be removed.
optical distortion and excessive thinning of the
plastic . The initial sanding should then be Buffing
followed by similar treatments , using successive
ly finer grades of sandpaper in the following In order to remove the fine, hairline scratches
229
aused by sanding, transparent plastic may be is then used to bring the plastic to a high polish.
uffed. It is often possible to remove scratches Both wheels are made up of numerous layers of
y buffing alone , provided the scratches are not cloth discs , but the abrasive wheel is made hard
oo deep by several rows of stitches, as shown in the
There are a number of standard commercial illustration . The finish wheel is unstitched with
uffing compounds satisfactory for use on trans spacers (washers ) mounted between every fourth
arent plastic enclosures. They are usually or fifth cloth disc .
composed of very fine alumina or similar Power for turning the buffing wheel may be
brasive in combination with wax , tallow, or > supplied by mounting it in a portable drill, as
rease binders. They are available in the form of shown in figure 8-16 , or a pedestal-type machine
>
ars or tubes for convenience in applying to the similar to the one shown in figure 8-17 may be
uffing wheel . used .
Plain tallow is often applied to the buffing At the start of each buffing operation , the
heel. It may be used in addition to buffing plastic must be clean and dry. Some of the
ompound , or may be used alone . In the latter buffing compounds now available will leave the
ase , tallow functions similar to wax inasmuch surface clean so that washing is not necessary .
s it fills in hairline scratches and gives a high Where necessary , however, washing should
loss to the surface . follow each step in buffing.
Buffing wheels are made of cotton cloth or If a panel has been sanded previously or is
elt . For removing scratches caused by sanding, deeply scratched , the abrasive wheel should be
n “ abrasive ” wheel and a “ finish ” wheel are used first.
eeded . (See fig . 8-15 . ) The abrasive wheel , Apply fresh compound to the wheel and buff
which is relatively hard and to which buffing lightly along and across all scratches. Keep the
ompound is applied , is used for removing the plastic or wheel in motion with relation to each
leeper scratches. The finish wheel , which is soft, other to prevent generating too much heat, thus
damaging the plastic .
Complete the buffing operation by using the
FINISH WHEEL
finish wheel , bringing the plastic surface to a
N
O
high gloss.
W
After all scratches have been removed with

the finish wheel , a coat of wax should be applied
by hand .
CAUTION : Hand polishing is recommended
in critical vision areas. Overheating transparent
plastic , by buffing, induces internal stresses and
optical distortions .
INSTALLATION OF
PLASTIC PANELS
There are a number of methods of installing

transparent plastic panels in aircraft, some of
ABRASIVE WHEEL which are shown in figures 8-18 through 8-21 .
Which method the aircraft manufacturer uses
depends upon the position of the panel in the
aircraft, the stresses to which it will be
subjected, and a number of other factors. In
installing a replacement panel , always follow the
AM.394 same mounting method used by the manu
Figure 8-15 . - Buffing wheels. facturer of the aircraft.
230
AM.395
Figure 8-16 . - Buffing wheel mounted in portable drill .
The following general rules apply to all types Since plastic expands and contracts three
of mountings. Fitting and handling should be times as much as metal , suitable allowances for
done with masking paper in place , although the dimensional changes with temperature must be
edges of the paper may be peeled back slightly made. Minimum clearances between the frame
and trimmed off for installation . and the plastic are listed in NavAir 01-1A- 12.
Since transparent plastic is brittle at low Clearance should be equally divided on all sides.
temperatures, installation of panels should be Screw torquing procedures should be in ac
done at normal temperatures . cordance with the applicable Maintenance
Plastic panels should be mounted between Instructions Manual . Plastic panels should not be
some type of gasket material to make the installed under unnatural stresses. Each screw
installation waterproof, to reduce vibration, and must be torqued as specified to enable it to
to help distribute compressive stresses on the carry its portion of the load. If a plastic panel is
plastic. Minimum packing thickness is 1/16 inch. installed in a binding or twisted position and
Rubber, fiber glass impregnate, and nylon are screws are not torqued correctly , the plastic
the most commonly used gasket materials . panel may fail while the aircraft is undergoing
231
AM.396
Figure 8-17 . - Pedestal type buffer with stitched and unstitched cloth wheels.
normal taxiing and flight operations. each screw is removed from the panel, it is
During the removal of a plastic panel , there installed in its respective position on the card
may be several different lengths of screws to be board . This is done with each screw as it is
removed . The AMS will save a lot of time if he removed .
acquires the habit of keeping screws separated. During installation of the panel , each screw is
An easy way to do this is to draw a diagram of removed from the cardboard and reinstalled in
the panel on cardboard. Puncture each screw 1
the same hole from which removed until all of
hole, with an awl, through the cardboard . As
> the screws are reinstalled.
232
PLASTIC FACE SHEET

// PLASTIC SHEET
T BUTYRAL
INNER LAYER
T
3T
2T LAMINATED
SYNTHETIC
FIBER
CLOTH
IT iż LAMINATED
SYNTHETIC
FIBER
CLOTH
AM.398
AM.397 Figure 8-19 . - Approved edge attachment for laminated
Figure 8-18 . - Approved edge attachment for solid plastic .
plastic.
233
PLASTIC PLASTIC SHEET

LAMINATE
SYNTHETIC FIBER
RUBBER CLOTH LOOP
EXTRUSION
SPECIAL
EXTRUSION
AM.399
RETAINING
Figure 8-20 . - Typical sighting dome attachment. CABLE
FRAME
SKIN
AM.400
Figure 8-21. - Typical loop edge attachment.
234
CHAPTER 9
LANDING WHEELS, TIRES, AND TUBES
WHEELS Some wheels are designed for use with tires

and tubes while others are designed for use with
The AMS- must have the knowledge and tubeless tires . Those designed for use with tires
professional ability to change wheel and tire and tubes have knurled flanges to prevent tire
assemblies, repack and replace wheel bearings , slippage on the wheel . Wheels for use with
and build up tires, as well as practice the safety tubeless tires have the wheel sections sealed by
precautions related to these procedures. General an O -ring and employ special valves which are a
ly , the wheels require only normal upkeep and part of the wheel .
take up little of the AMS' time ; however , he
may be stationed where wheel assemblies DIVIDED ( SPLIT) TYPE WHEEL
frequently come in contact with salt water or
salt air . In an area such as this, the AMS will Figure 9-1 illustrates a typical divided (split)
spend a considerable amount of time stripping type wheel . This type of wheel is divided into
paint and treating the wheels to help control or two halves, which are held together by bolts and
eliminate corrosion . Wheels are removed from nuts. The two halves are sealed by an O -ring on
aircraft frequently for tire changes, inspections, wheels designed for use with tubeless tires. Each
lubrication of wheel bearings, and inspection of wheel half is statically balanced so that any two
the wheel brakes . Familiarity with the various opposite halves of the same size and type ( part
types of wheels , their construction features, and
how they are properly installed on the aircraft
are therefore highly important items .
This section describes the types of wheels
currently used on naval aircraft , illustrates the
various components of a typical wheel assembly ,
and describes the procedure for removing and -- willa
installing a wheel properly. Installation of each
component in its proper order in the wheel hub ,
and correct adjustment of the wheel bearings are
especially important items .
Aircraft landing wheels are made from either
aluminum alloys or magnesium alloys . Both of
these materials provide a strong, lightweight
wheel , requiring very little maintenance.
>
Wheels used on naval aircraft are of two

general types - the DIVIDED type and the
DEMOUNTABLE FLANGE type. Both of these
000
designs make tire changing a fairly simple AM.401
operation. Figure 91. -Typical divided ( split) type wheel .
235
no. ) may be joined together to form one wheel These designations refer to the features of
assembly . Thus, if the outboard half of a wheel construction and the types of tire casings with
is damaged beyond repair , a new outboard half which they are used . The dimensions by which
can be drawn from supply and assembled to the wheels are identified are not necessarily the
old inboard half. This type of wheel is used on dimensions of the wheels themselves, but refer
nose , main , and tail gears. to certain dimensions of the tire. Size designa
tions are discussed in the section on tires.
DEMOUNTABLE FLANGE TYPE WHEEL Similarity of one wheel to another in size and
shape is no proof that the wheels can be
The demountable flange landing wheel is interchanged , since one wheel may be designed
made so that one flange of the wheel can be for heavy duty while the other one is designed
removed for changing the tire. The flange is held to carry a lighter load. Also, one wheel may be
in place on the assembled wheel by a lockring or designed for use with an entirely different type
bolts. The wheel is balanced with the flange of brake assembly.
mounted on the wheel , and both the wheel and
flange are marked . To insure proper balance of TYPICAL WHEEL ASSEMBLY
the wheel when assembling , these two marks
should be lined up together . Figure 9-2 il A complete wheel assembly is shown in figure
lustrates a typical demountable flange type 9-3 . The wheel casting ( 6) is the basic unit of the
landing wheel . This type wheel is more common wheel assembly . It is to this part that all other
ly used on the main landing gear. components of the assembly are assembled and
upon which the tire is mounted .
The demountable flange (4) is assembled to
the wheel with the chief purpose being to
simplify tire removal and installation . The
demountable flange lockring (3 ) secures the
flange to the wheel. It is fitted into a groove in
the wheel casting.
28.
200 AM.402
The bearing cups ( 12) and ( 13 ) are shrink
fitted into the hub of the wheel casting and are
the parts on which the bearings ride. The
bearings (5 ) and ( 7) are the tapered roller type.
Each bearing is made up of a cone and the
rollers. This type bearing absorbs side thrust as
well as radial loads and landing shocks. Bearings
must be cleaned and repacked with grease
periodically , as discussed later in the chapter.
A three -piece grease retainer retains the grease
in the inboard bearing and keeps out dirt and
Figure 9-2 . - Typical demountable flange type wheel. moisture . It is composed of a felt seal (9) and an
inner and outer closure ring (8 ) and ( 10) . A
Wheels are further classified into the follow lockring ( 11 ) secures the assembly inside the
wheel hub .
ing types :
The hubcap (2) seals the outboard side of the
Type I -Smooth contour. hub . It is also secured with a lockring ( 1 );
Type II -High pressure . however, on some aircraft the hubcap is secured
Type III -Low pressure . with screws .
Type IV - Extra low pressure. All wheels designed for use on the main
Type VI -Low profile. landing gear are equipped with braking
Type VII -Extra high pressure . components . These components are attached to
Type VIII -Extra high pressure (low profile ). the wheel casting and may consist of either a
236
Chapter 9 - LANDING WHEELS, TIRES, AND TUBES
15
1 2 3 12
00 -14
-13
7
obo
0
5
ok,
AM.403
1. Hubcap lockring. 9. Inboard bearing felt seal.
2. Hubcap. 10. Inboard bearing closure ring.
3. Demountable flange lockring. 11 . Inboard bearing closure lockring.
4. Demountable flange. 12. Outboard bearing cup .
5. Outboard bearing. 13 . Inboard bearing cup .
6. Wheel casting. 14. Disc drive key.
7. Inboard bearing. 15. Fusible plug.
8. Inboard bearing closure ring.
Figure 93. -Typical wheel assembly.
brake drum or brake drive keys. The wheel in may occur and cause severe damage to
figure 9-3 is equipped with drive keys ( 14). This equipment and personnel. To counteract this
type wheel is designed for use with disc type situation , aircraft manufacturers have developed
brakes. Those equipped with brake drums are a safety device called a fusible plug . The fusible
designed for use with expander tube brakes, or plug ( 15 ) contains an alloy which will melt and
the old shoe type brake which is no longer used permit the tire to deflate in the event the wheel
on naval aircraft. is exposed to excessive heat from overbraking or
The trend in the armed forces seems to be other causes . This release of air pressure will
larger and faster aircraft, which means heavier prevent damage to personnel or equipment.
loads and higher landing speeds. Friction caused Wheels which contain fusible plugs should have a
by long rollouts, taxing, etc , cause heat to be metal tag affixed which reads, “Fusible Plugs
absorbed by the wheel. Possible wheel failure Installed .”
237
ICTURA
ALANCING OF WHEELS order ) they are lubricated with Specification

MIL -G -81322A, wide temperature range grease.
Wheel assemblies are statically balanced at the Wheel bearings may be lubricated either by
me of their manufacture. The method of pressure equipment or hand methods as il
alancing is such that the limits of the assembly lustrated in figures 9-4 and 9-5 . However, the
mbalance will not be exceeded by changing pressure method is recommended since it is
najor portions of the rotating assembly , such as easier, faster, reduces the
the possibility of
rake drums or demountable flanges. Split contamination, and , when utilized correctly , will
>
heels are balanced so that assembling the wheel assure a more even distribution of grease within
alves in alternate positions or assembling halves critical areas. Felt grease retainers are cleaned or
f different wheels together will not unbalance replaced if saturated with lubricant. Bearing
ne assembly beyond the specified limits. cups are inspected for wear and damage .
alance weights are securely attached in such a NOTE : Insure bearings are completely dry
anner that the wheel performance is not prior to packing with lubricant . Water or
mpaired . Any weights which have been added condensation will cause bearings to rust.
a wheel to bring it within proper balance Fusible plugs are inspected to detect fused or
hould not be removed . However , if a wheel has partially fused plugs. Figure 9-6 gives examples
een rendered out of balance due to loss, of fusible plugs ; the top row shows usable plugs,
reakage, or accidental removal of the balance the second row partially fused plugs , and the
eights, the wheel must be rebalanced in accord bottom row illustrates fused plugs. Wheels
nce with existing instructions. containing either partially fused or fused plugs
must have all plugs contained in the wheel
VHEEL MAINTENANCE replaced . Then the wheel must be inspected for
AND INSPECTION damage using the procedures listed in the ap
plicable Overhaul Instructions Manual for that
The AMS removes wheels from aircraft specific wheel.
eriodically for a thorough inspection . Wheels In reinstalling the wheel on the aircraft,
re cleaned , using a suitable solvent, prior to proper adjustment of the bearings is extremely
nspection. The wheels are then inspected for important. The procedure is as follows:
orrosion , cracks , distortion , condition of paint
or protective coatings , and checked for evidence 1. Tighten the axle nut while spinning the
of overheating due to braking action . wheel by hand.
CAUTION : When an aircraft wheel is to be 2. When the wheel no longer spins freely,
emoved from the aircraft, the air must be back off the axle nut one castellation ( 1/6 turn ).
emoved from the tire prior to removing the When properly installed and adjusted , the wheel
vheel . This precaution must be taken because of will turn freely, but will have no side wise
he possibility that the bolts in split type wheels movement . (This procedure may vary from one
night have been sheared from landing, thus aircraft to another ; the AMS must refer to the
causing the wheel halves to separate when the applicable Maintenance Instructions Manual . )
xle nut is removed . In the past , several people 3. Safety the axle nut , and install hubcap and
have been killed by their failure to remove the lock it in place.
ir from the tire before removing the axle nut.
Wheel bolts used to fasten divided (split) type AIRCRAFT TIRES
vheels are inspected for cracks or condition .
This inspection is normally performed using the Proper care and maintenance of tires have
nagnetic particle inspection in accordance with always been important items in aircraft main
-pplicable directives. tenance; however, with the development and use
Braking surfaces are checked for looseness of the fast-landing aircraft of today , careful tire
und for excessive or uneven wear. Wheel bearings maintenance has become increasingly important.
re cleaned with an approved solvent. After the Aircraft tires are built to withstand a great deal
vheel bearings are cleaned and inspected (in that of punishment, but only by proper care and
238
Chapter 9 - LANDING WHEELS , TIRES , AND TUBES
AM.404
Figure 9-4 . -Hand lubrication of wheel bearings.
maintenance can they give safe and dependable in construction except that they have a rubber
service. inner liner that is integral with the inside surface
of the tire for air retention, and they also
TIRE CONSTRUCTION employ materials and construction in the bead
area designed to form a seal with the wheel
Figure 9-7 shows the construction details of a flange. Wear indicators ( tread depth holes
tube-type aircraft tire. Tubeless tires are similar located in the tread area or lands located in the
239
The BEADS are multiple strands of high

tensile strength steel wire imbedded in rubber
and wrapped in strips of open weave fabric. The
beads hold the tire firmly on the rims and serve
as an anchor for the fabric plies turned up
around the bead wires.
The CHAFING STRIPS are one or more plies
of rubber -impregnated woven fabric wrapped
around the outside of the beads. They provide
additional rigidity to the bead construction and
prevent the metal wheel rim from chafing the
tire. Tubeless tires have an additional ply of
rubber over the chafing strips which functions as
an air seal .
The BREAKERS are one or more plies of
cord or woven fabric impregnated with rubber.
When used , they are located between the tread
>
rubber and the cord body, and provide extra

reinforcement to prevent bruise damage to the
tire. Breakers are not considered part of the cord
AM. 1215 body .
Figure 9-5 . - Pressure lubrication of wheel bearings.
Tread Patterns
bottom of the tread grooves) have been in The tread is a layer of rubber on the outer
corporated into select tires as an aid in
circumference of the tire . There are four designs
measuring tread wear. of tread patterns available for use on naval
The CORD BODY consists of multiple layers aircraft.
of nylon with individual cords arranged parallel The tread patterns may be any of the follow
to each other and completely encased in rubber. ing designs .
The fabric, therefore, has all its strength in only
one direction . Each layer of coated fabric 1. Plain . A plain tread is one with a smooth
constitutes one ply of the cord body. Adjacent uninterrupted surface.
cord plies in the body are assembled with the 2. Nonskid . A nonskid tread is any grooved
cords crossing nearly at right angles to each or ribbed type tread.
other. This arrangement provides a strong and 3. Ribbed . A ribbed tread pattern is one
Flexible construction that distributes impact having three or more continuous circumferential
hocks over a wide area . The main function of ribs .
Che cord body is to give the tire tensile strength 4. Channel. Channel tread tires are heavier
to resist internal pressures and to maintain tire than the respective standard types to reduce
hape . It must be able to withstand severe wheel shimmy and improve ground handling of
lexing, heat , and impact shocks during normal aircraft.
cire operations .
The TREAD is a layer of rubber on the outer Tread Construction
circumference of the tire. It provides the
wearing surface and protects the cord body The tread construction will be one of the
underneath from abrasion, cuts, bruises, and following types.
moisture . NOTE : Other tread types may be provided
The SIDEWALL is an outer layer of rubber under specific circumstances or as required by
djoining the tread and extending down to the applicable MS standards or drawings.
peads . Like the tread, it protects the cord body 1. Rubber tread . A rubber tread is con
From abrasion, cuts , bruises, and moisture. structed from 100 percent new (no reclaim )
240
Chapter 9 - LANDING WHEELS , TIRES , AND TUBES
@
629
52
Ol).
USABLE FUSE PLUGS
PARTIALLY FUSED PLUGS
ya
FUSED PLUGS
NOTE : WHEELS CONTAINING FUSED OR PARTIALLY FUSED

PLUGS MUST HAVE ALL PLUGS REPLACED .
AM.405
Figure 9-6 . - Fusible plugs.
rubber. It may be new natural rubber, new tread . (See fig. 9-8 . )
synthetic material, or a blend of new natural and 4. Reinforced cut- resistant tread . A re
new synthetic materials. inforced cut- resistant tread is one that combines
2. Cut-resistant tread . A cut -resistant tread is the features of both the cut-resistant and
one which has improved cut -resistant properties reinforced -tread design.
that are imparted to the tire by incorporating
into the undertread a barrier that resists penetra Ply Rating
tion of cutting objects.
3. Reinforced tread. A reinforced tread is The reference to the number of cord fabric
one constructed with fabric cord or other plies in a tire has been superseded by the term
reinforcing materials as an integral part of the " ply rating .” This is used to identify a given tire
241
BREAKERS
OR INSERTS
TREAD
the AS PLIES
SIDEWALL
CHAFING CORD BODY

STRIPS
PLY BEAD
TURN - UPS AREA
BEAD WIRES
AM.406
Figure 9-7 . - Typical aircraft tire construction .
with its maximum recommended load for

specific types of service. It does not necessarily
represent the number of cord fabric plies in a
tire. Most nylon cord tires have ply ratings
greater than the actual number of fabric plies in
the cord body .
Type and Size Designation

There are seven types of tires used on aircraft
now in service . Figure 9-9 illustrates the various
types and how the size of each is designated.
Dimension A in the illustration is the outside
diameter of the tire . Dimension B is the cross
AM. 1216 sectional width of the tire at its widest point.
Figure 9.8 . - Reinforced- tread construction . Dimension C is the inside diameter of the tire .
242
SMOOTH HIGH LOW

-B B
CONTOUR (SC ) PRESSURE (HP) PRESSURE ( LP )
ОС
A
TYPE 1 TYPE II TYPE III
16
Size designated by A in inches Size designated by Ax B in Size designated by B - C in inches .
for main wheels or A in inches and inches . B is given in inches and decimals .
decimals for tailwheels . Example : 32 x 8 C is given in inches .
Example : Mainwheel - 56 Example : 16.00-16
Tailwheel- 12.50
B EXTRA LOW LOW

-B -B
PRESSURE (ELP) PROFILE (LPR ) EXTRA HIGH
PRESSURE (EHP)
TYPE IV С А.
TYPE VI
TYPE VII
ID
Size designated by Ax B - C in Size designated by Ax B - C in
inches. Size designated by AxB in inches. A
inches . A is given in inches . B is given in inches . B is given in inche
Example : 29x13-5 and C may be given in inches and decimals to prevent mistake with
or inches and decimals .
Type I tires of similar size .
Example : 22x7.25-11.50 Example : 26x6.6
EXTRA HIGH
PRESSURE
-B LOW PROFILE
(EHP LPR )
Size designated by AxB -C in
inches . A is given in inches . B
А с and C may be given in inches
TYPE VIII or inches and decimals .
Example : 26x8.0-14
AM.408
Figure 9.9 . - Types and size designation of tires.
Identification Markings Maintenance Action Forms (MAF ) and other

required maintenance forms. Each marking
The AMS should be familiar with the mark which is engraved or embossed on the sidewall
ings on the sidewall of tires. Some of this for identification purposes is discussed in this
information is needed to facilitate completion of section .
243
SIZE AND TYPE . - The size of the tire is plies of the cord body . They relieve air that
ndicated as previously explained, and the type accumulates in the cord body by normal
s indicated by the Roman numeral designated diffusion through the tubeless tire liner and the
or that type of tire . tire carcass. Vent holes in tubeless tires are
PLY RATING . -On some tires " ply rating” is marked with a bright green dot .
bbreviated as “ PR ” . NOTE : Tubeless tires must be marked TUBE
CORD BODY MATERIAL . - Type of material LESS .
Esed in the carcass if other than nylon. In addition to the above markings, all tires are
DATE OF MANUFACTURE AND SERIAL marked with the manufacturer's name or trade
JUMBER. -The date of manufacture of the tire mark , manufacturer's mold number, and
s included in the serial number . The serial country of manufacture (if other than USA) .
lumber consists of a maximum of 10 positions. RETREAD TIRE IDENTIFICATION.- The
Che first four positions indicate the date of identification data required of the original tire
nanufacture in the form of a Julian date ( last manufacturer is required to remain on the tire
ligit of the year followed by the day of the and must be replaced by engraving or embossing
ear, i.e. , 23 May 1968 is written 8144 ). The if removed during retreading. In addition , the
ext positions (not to exceed six ) selected by retread tire is required to be legibly marked and
he manufacturer may be either numbers or identified as follows: The letter " R " or " TR "
etters , or a combination of both . followed by a numeral “ 1” , “ 2 ” , or “ 3 ” , etc. , to
>
BALANCE MARKER.- The balance marker is indicate the first, second, or third time the tire
red dot permanently branded into the sidewall has been retreaded , Julian date of retread
of the tire immediately above the bead . It manufacture, and the name of the retread
ndicates the lightweight point of the tire and manufacturer and plant location .
nust be placed next to the balance marker on When a retread tire has a cut repair extending
he inner tube when mounting. >
into the carcass plies, a letter " c " is placed in the
CUT- LIMIT IDENTIFICATION . - The cut new rubber in the shoulder area directly
amit dimension is expressed in thirty-seconds of adjacent to the cut repair.
in inch , and is rounded to the next smaller
hirty -seconds of an inch increment when a STORAGE OF TIRES
raction of a thirty -second inch is involved. It is
nolded in a minimum of two places equally The life of a tire is directly affected by
paced on each sidewall of the tire. storage conditions. Tires should be stored
TREAD CONSTRUCTION.- Tires with fabric indoors in a dark, cool, dry room . It is necessary
einforced tread are marked FABRIC TREAD . that they be protected from light ( especially
VENT MARKINGS . - Tube -type tires with sunlight) to prevent checking. This may be
nflation pressures greater than 100 psi and all accomplished by painting the storeroom
ubeless tires must be suitably vented to relieve windows. They must also be protected from
rapped air . Tube-type tires are vented in either excessive heat , strong air current, dirt, and
of two ways . The first method uses air bleed dampness. Tires must not be allowed to come in
idges on the inside tire surface and grooves on contact with oils, greases, solvents, or other
he bead faces. The ridges and grooves channel petroleum products that cause rubber to soften
o the outside the air trapped between the inner deteriorate . The storeroom should not
ube and the tire . The second method uses four contain any kind of sparking electrical equip
or more vent holes that extend completely ment that would produce ozone , nor any
through each tire sidewall. They relieve both fluorescent lights.
ocketed air and air that accumulates in the Tires should be stored vertically in racks,
ord body by normal diffusion through the according to size as shown in figure 9-10. The
nner tube and tire . Tube-type tire vent holes are edges of the racks must be planed down or
narked with an aluminum or white colored dot. designed so that the tire tread does not rest on a
Tubeless tires have vent holes that penetrate sharp edge. Tires must never be stacked
rom the outside of the tire sidewall to the outer horizontally in piles. The issue of tires from the
244
Chapter 9 - LANDING WHEELS, TIRES , AND TUBES
1
11
1
AM . 1217
Figure 9-10.-Tire storage rack.
7
storeroom should be strictly on the basis of age safe service life. Military aircraft inner tubes and
from the date of manufacture so that the older tubeless tire liners are made of natural rubber to
tires will be used first, preventing the chance of satisfy extreme low temperature performance
deterioration of the older tires in stock . requirements. Natural rubber is a relatively poor
air retainer. This accounts for the high daily
INSPECTION AND inflation pressure loss and the need for frequent
7 MAINTENANCE OF TIRES pressure checks . If this check discloses more
*
than a normal loss of pressure, check the valve
There are two types of inspections conducted core for leakage by putting a small amount of
on the tires; one is conducted with the tire saliva or water on the end of the valve and watch
I
mounted on the wheel, while the other is for bubbles. Replace the valve core if it is
conducted with the tire dismounted . leaking. If no bubbles appear, it is an indication
1
that the inner tube (or tire) has a leak . When a
Mounted Inspection tire and wheel assembly shows repeated pressure
។
loss exceeding 5 percent of the correct operating
During the first preflight inspection each day, inflation pressure, it should be removed from
the tires must be inspected for correct pressure, the aircraft and sent to the IMA.
tire slippage on the wheel ( tube type tires), cuts, After making a pressure check , always replace
wear, and general condition . Tires must also be the valve cap , insuring that it is screwed on
inspected before each flight for obvious damage fingertight. The cap prevents moisture, salt, oil,
that may have been caused during or after the and dirt from entering the valve stem and
previous flight. damaging the valve core . It also acts as a
Maintaining the correct inflation pressure in secondary seal if a leak should develop in the
an aircraft tire is essential to obtain maximum valve core .
245
Objects being pried from the tire frequently are

ejected suddenly and with considerable force.
Therefore, to avoid eye injury , safety glasses or a
face shield must be worn. (A gloved hand over
the object may be used to deflect it . )
Tires must be removed from the aircraft when
the tread pattern is worn to less than 1 /32 -inch,
at any spot , or to the limits of the tread wear
indicators; if the tire's sidewall cord body fabric
is exposed ; or if the tread cuts exceed the depth
specified on the sidewall of the tire or in the
Technical Manual , Aircraft Tires and Tubes,
>
NavAir 04-10-506 . Figure 9-12 shows the

method for measuring cuts, cracks, and holes.
>
Dismounted Inspection
Whenever a tire has been subjected to a hard

landing or has hit an obstacle , it should be
dismounted for a complete inspection to deter
mine if any internal injuries have occurred. The
tire beads should be spread and the inside of the
tire inspected with the aid of a light . If the lining
has been damaged or there are other internal
AM.409 injuries, the tire should be removed from service.
Figure 911. -Tire slippage mark. Check the entire bead area and the area just
above the bead for evidence of rim chafing and
damage . Check the wheel for damage which may
Tires which are equipped with inner tubes, damage the tire after it is mounted.
and operate with less than 150 psi, and all
helicopter tube type tires must utilize tire DISMOUNTING AND MOUNTING
slippage marks . The slippage mark is a red stripe
painted 1 inch wide and 2 inches long, extending During mounting and dismounting of tires,
equally across the tire side wall and the wheel safety is paramount . Compressed air and
rim as illustrated in figure 9-11 . Aircraft meeting nitrogen present a safety hazard, if the operator
the above requirements should be inspected for is not aware of the proper operation of the
tire slippage on the rim after each flight. If the inflation equipment and the characteristics of
markings do not align within 1/4 inch, the wheel the inflation medium . It is also very important
assembly must be replaced and the defective to know the wheel type and be familiar with the
assembly forwarded to the IMA for repair. manufacturers recommended procedure before
Failure to correct tire slippage may cause the attempting to dismount a tire. For specific
valve stem to be ripped from the tube. precautions concerning a particular installation,
During the visual inspection of tires for cuts, always consult the applicable Maintenance
wear, and general condition, any foreign objects Instructions Manual.
such as stones, glass, metal, or other materials
embedded in the tread should be removed . A Dismounting
common screwdriver or other blunt instrument
may be used. The AMS working in the tire shop should
WARNING : When probing for foreign recheck tires for complete deflation prior to
objects, extreme care must be used to prevent disassembling the wheel and breaking the bead
the probe from penetrating deeper into the tire. of the tire . Breaking the bead means separating
246
>
-CUT
NO
X
1 94
1. MEASURE REMAINING TREAD DEPTH .

2. MEASURE DEPTH OF CUT .
3. SUBTRACT THE DEPTH OF THE EVALUATE THIS
CUT AS 7/8 IN. LONG
REMAINING TREAD FROM THE DEPTH
OF THE CUT . THE RESULT IS THE
MEASUREMENT TO BE COMPARED WITH
THE LIMITS SPECIFIED IN NAVAIR
04-10-506 OR ON THE SIDEWALL OF
THE TIRE AS APPLICABLE . DEPTH IS READ AT
THIS POINT
4. ALL MEASUREMENTS SHOULD BE
MEASURED WITH A TREAD DEPTH GAUGE .
FSN 5210-357-5951
9/32
-5/32
4/32
AM. 1218
Figure 9-12 . - Method of measuring depth and length of cuts, cracks, and holes.
the bead of the tire from the wheel flange. When recommended by NavAir 04-10-506 . Other com
a tire has been completely deflated and set aside mercially available or locally fabricated equip
to await the bead -breaking operation, the valve ment which uses either a hydraulically actuated
core should be removed and a deflated tire flag cylinder or a mechanically actuated device may
(as shown in fig. 9-13 ) installed on the valve also be used , provided the equipment will not
stem . The tire flags should be so constructed as damage the tires or wheels. The bead -breaking
not to be installable unless the valve core has equipment shown in figure 9-14 is available in
been removed . two models. Model Lee- 1 is designed for installa
BREAKING THE BEAD. -The use of proper
-
tion and service in shore based facilities and
equipment for breaking the bead of the tire Model Lee-IX is an explosion-proof version of
away from the wheel flange will save materials the Lee- 1 intended for shipboard use .
and manhours. Aircraft tires, inner tubes, and The following is a step -by -step procedure in
wheels can be damaged beyond repair by the proper operation of the Model Lee -1 equip
improper mounting and dismounting equipment ment .
and procedures. The equipment in figure 9-14 is 1. Insure the tire is completely deflated .
247
TIRE
DEFLATED
VALVE
CORE SINI!
REMOVED DES
Figure 9-13 . - Deflated tire flag. AM.410
2. Determine the type and size of wheel to be

dism ounted and assemble the proper parts on
the drive shaft.
6. Using the UP pushbutton , raise the center
of the wheel to line up with the center of the
3. Push the outer centering rollers toward the bead -breaking disc .
front of the machine and roll the wheel (posi
7. Rotate the tire by pushing the tire rotating
tioned with the lockring side facing outward for toggle to the right. Position the front beadbreak
demountable flange wheels) on the outer center
ing disc against the outside bead of the wheel
ing rollers. Using the up and down pushbuttons, flange. If necessary, adjust the position of the
raise or lower the drive shaft to the proper hydraulic pump assembly by loosening the
height for the wheel being dismounted , and push position lock pin and sliding the pump to the
the wheel onto the drive shaft. If an open proper position. After turning the pump release
rimmed tire assembly is being dismounted omit valve clockwise as far as it will go , apply
step 4 and proceed to step 5 . hydraulic pressure against the bead by pumping
4. Insert the locking bar and turn about 90 the handle as illustrated in figure 9-15 . Use the
degrees counterclockwise. Mount the wheel cone guide handle to properly position the disc. Push
on the locking bar and insert the locking pin . the bead back far enough to allow the removal
5. Push the air valve switch to the right; this of the lockring or loose flange.
will clamp the wheel on the drive shaft. 8. Remove the lockring and loose flange. If
necessary use the bead shoes ( fig. 9-16) to hold
248
UP - DOWN
PUSH BUTTONS TIRE
ROTATING
SWITCH AIR VALVE
AIR SUPPLY
HYDRAULIC BEAD INLET
BREAKING PUMPS
DRIVE SHAFT
LARGE WHEEL
CONES AND
110 - V POWER PACK LOCKING BAR
( DRIVE FOR
HYDRAULIC LIFT )
SHOE
BEAD SHOES SPREADING
AND HOLDER CONE
: WHEEL SHOES
SMALL WHEEL
CONES
AM.411
Figure 9. 14.- Aircraft wheel holder and tire bead breaking machine.
the bead back while removing the lockring. 9. Repeat the bead -breaking operation
Release and retract the front bead -breaking disc against the rear surface of the tire, using the rear
by turning the release valve counterclockwise. bead breaking assembly .
249
..
COM
BEAD SHOES
©
AM.412
Figure 9-15 . - Using bead -breaking pump.
10. On all divided (split) type wheels, after AM.413

he beads are broken, remove all nuts and bolts Figure 9.16 . - Shaft arranged to hold tire bead while
while the wheel assembly is still mounted on the removing lockring.
machine .
Dismounting Divided (Split) Wheels . - Tire
pead is broken away from the wheel and nuts hex nut ( if any) and push the valve away from
nd bolts are removed as previously described. the seated position to prevent damage to the
NOTE : If the tire is a tube type, remove the inner tube valve attachment when breaking the
nex nut (if any) and push the valve away from bead .
he seated position to prevent damage to the If trouble is encountered in removing the
nner tube valve attachment when breaking the flange while the wheel is mounted on the bead
cire bead loose . Remove the wheel assembly breaking machine, remove the tire from the
From the tire. If the tire is a tubeless type , machine. Lay the tire and wheel assembly flat
emove the wheel seal carefully from the wheel with the demountable flange side up. Drive the
half and place it on a clean surface. Wheel seals demountable flange down by tapping with a
n good condition may be reused if replacement rubber, plastic, or rawhide -faced mallet, far
eals are not available. If the tire is a tube type, enough to enable removal of the locking ring.
emove the inner tube . Inner tubes can be reused CAUTION : Extreme care must be taken
f in good condition, and if less than 5 years old . when breaking the beads loose and when
Dismounting Demountable Flange Wheels. -
removing the lockring on some demountable
fire bead is broken away from the wheel as flange wheels. The toe of the demountable
previously described. flange on these wheels extends very close to the
NOTE : If the tire is a tube type, remove the tube valve stem . Excessive travel of the
i
250
demountable flange, when removing the lock inches long in contrasting colors. It is located on
ring, or of the tire bead , when breaking the the valve side of the tube . The balance mark on
beads loose , will damage the rubber base of the a tire is a red dot approximately 1/2 inch in
inner tube valve . diameter. It is located on the sidewall near the
If the tire is a tubeless type , remove the wheel bead .
seal carefully and place it on a clean surface . Inflate the tube until it is rounded out and
Wheel seals in satisfactory condition may be place the valve -hole half of the wheel into
reused if replacement seals are not available . position in the tire. Push the valve stem through
Turn the tire and wheel assembly over, and lift the hole . Insert the other half of the wheel and
the wheel out of the tire . If the tire is a tube align the boltholes.
type, remove the inner tube. Inner tubes may be NOTE : All bolts must be magnetic particle
reused if in a satisfactory condition . Remember inspected to insure they are not defective. Install
to keep the wheel flange and locking ring four bolts, nuts, and washers 90 degrees apart.
together as a unit to avoid possible mismatch Start the bolts by hand , and draw up evenly
during remounting . until the wheel halves seat . Install the remaining
bolts , nuts, and washers. Tighten the bolts in a
Mounting crisscross order to prevent distorting the wheel
or damaging the inserts . A pneumatic powered
Prior to mounting a tire on a wheel , the AMS impact wrench may be used, provided the
must inspect the tire for condition and insure torque obtained does not exceed 25 percent of
the inside of the tire is free of foreign materials. the specified final torque required for the wheel .
The inner tube must be inspected for bead Use a currently calibrated torque Wrench and
chafing, thinning, folding, surface checking, heat tighten each bolt in increments of 25 percent of
damage, fabric liner separation, valve pad separa the specified torque value in a crisscross order
tion , damaged valves, leaks, and other signs of until the total torque value required for each
deterioration . The wheel assembly is inspected bolt in the wheel has been reached .
in accordance with current directives. NOTE : When " Lubtork ” is specified on the
Mounting of divided (split ) and demountable wheel half, coat all treads and bearing surfaces
flange wheel assemblies is covered here to of boltheads with MIL - T -5544 antiseize
acquaint the AMS with the basic procedures. compound. “ Lubtork ” must not be used on
For specific information in regard to a given tire magnesium wheels. For magnesium wheels use
assembly , consult the applicable Maintenance MIL -G -21164 lubricant. All excessive lubricant
Instructions Manual. should be removed .
MOUNTING DIVIDED ( SPLIT ) WHEELS. Prior to mounting tubeless tires , check the
All wheel halves should be matched by year and tire sidewall for the word “ Tubeless .” Treat all
month of manufacture as closely as possible . tires not so marked as tube type tires. When
Wheel assemblies received from overhaul having mounting tubeless tires , install the valve stem
matching overhaul dates on both rims should be (valve core removed ) in the wheel assembly.
maintained as matched assemblies. In the event a Removing the valve core prevents unseating of
wheel assembly is received or made up of wheel the wheel seal by pressure built up when the tire
halves having different overhaul dates, the wheel is installed . Insert one wheel half in the tire and
overhaul should be based upon the earlier date. position the tire so that the balance marker on
All wheels should fit together easily without the tire is located at the valve stem . Install the
forcing. wheel seal , which has been lubricated with a
When mounting a tube type tire, dust the light coat of MIL -G -4343 lubricant, on the outer
tube with talcum powder and insert the tube in wheel half. Install the other wheel half and align
the tire. The tire should be positioned so that the boltholes. Install bolts, washers, and nuts in
the balance marker on the tube is located next the same manner as explained earlier for the
to the balance marker of the tire . wheel assembly containing inner tubes.
NOTE : The balance marker on an inner tube MOUNTING DEMOUNTABLE FLANGE
is a stripe approximately 1/2 inch wide and 2 WHEELS . - When mounting a tube type tire on a
251
demountable flange wheel, the inner tube is tube type tires which are inflated to 150 psi or
prepared and inserted in the tire in the same less.
manner as on a split or divided wheel. The wheel A loss of pressure , not to exceed 5 percent,
s then positioned on a flat surface with the will be experienced during the first 24 hours
fixed flange down . Push the tire on the wheel after initial inflation of a new tire . This is
assembly as far as it will go , guiding the valve attributed to normal tire stretch and the tire
stem into the valve slot with the fingers. Install pressure should be adjusted accordingly .
the demountable flange on the wheel , and secure INFLATION OF NEW TIRES . - After the
the locking ring in accordance with the assembly buildup of a tire and when the tire is ready to be
nstructions required by the applicable wheel inflated , it is placed within a safety cage for
manual . inflation. A typical safety cage is shown in figure
When mounting a tubeless type tire on a 9-17 . The method of inflation used depends on
demountable flange wheel , install the valve stem whether a tube or tubeless type tire is being
valve core removed) in the wheel assembly. inflated .
Removing the valve core prevents unseating the Inflation of Tube Type Tires. -Remove the
wheel seal by pressure built up when the tire is valve core and place the wheel assembly in the
nstalled . The wheel seal is lubricated with the
same lubricant and in the same manner as
previously mentioned for split or divided wheel
assemblies using tubeless tires. The wheel seal is
nstalled on the flange sealing surface. Install the
demountable flange on the wheel, and secure the
ocking ring in accordance with the assembly
nstructions required by the applicable wheel
manual .
fire Inflation
The AMS is required to have a thorough

nowledge of servicing tires. The equipment
ised and procedures for inflating tires are
covered in chapter 12. The actual inflation
nedium is covered in the following section .
In the past, aircraft tires have been inflated
vith clean dry air. The trend now is from aa clean
Iry air source to nitrogen . Nitrogen ,
BB -N -411B ) type 1 class 1 , is preferred because
oxygen in the air reacts with the tire rubber at
high temperatures and pressure. This causes
leterioration , reduces the tire life, and consti
utes a blowout hazard . If circumstances dictate
hat air rather than nitrogen must be used , the
ir line from the compressor must be equipped
vith a trap to remove all water and oil.
All high -pressure inflation sources must be
equipped with reducing valves that limit the line
ressure to 600 psi or 50 percent above the
naximum tire inflation pressure , whichever is
he lesser.
Slippage marks must be painted on all newly AM.414
nounted helicopter tube type tires and other Figure 9.17 . - Safety cage for inflation of tires.
252
from the safety cage , and the cause of the leak

determined . If a slow leak is detected, the air
retention test should be extended to 24 hours.
The tire should not be issued until remedial
action is taken if the leakage exceeds 5 percent .
Inflation of Tubeless Tires.- Tubeless tires are
inflated in the same manner as previously
explained for tube type tires except it is not
necessary to inflate tubeless tires with the valve
core removed .
RETREADING AND REPAIR
The Navy considers all aircraft tires to be

potentially retreadable. Used aircraft tires
should not be discarded or scrapped until it has
been definitely determined that they are unfit
for further use .
All tires removed from aircraft should have
the injuries marked with a wax crayon . The tire
is then turned in to the Intermediate Main
AM. 1219 tenance Activity (IMA) for screening. The IMA
Figure 9-18.- Remote inflator assembly. will determine if the tire is serviceable or
nonserviceable and take the necessary action .
safety cage . Attach a remote tire inflation gage Serviceable Tires

assembly ( figure 9-18 ) to the valve stem . Check
to make sure the inner tube is not being pinched Serviceable tires are those judged suitable for
between the tire bead and the wheel flange. continued service use by the tire shop personnel.
Check demountable flange wheels to make sure They should be retained in service until the
the demountable flange and locking ring are remaining tread at any spot is 1/32 inch thick or
seated properly . Secure the safety cage door and to the limits of the tread wear indicators.
inflate the tire to its maximum operating Defects permitted are cut limits contained on
pressure to seat the tire beads against the rim the tire sidewall or as listed in the technical
flanges. Deflate the tire, install the valve core , manual, Aircraft Tires and Tubes, NavAir
and reinflate the tire to its maximum operation 04-10-506 . Cuts are permitted in the sidewall
pressure. Allow the tire to remain at this provided they do not penetrate to the cord body
pressure for a minimum of 10 minutes. At the fabric .
end of this 10 -minute period, there should be no
detectable pressure loss. Nonserviceable Tires
If no pressure loss is detected, the tire
pressure is reduced to 50 percent of the Nonserviceable tires may be nonretreadable or
maximum operating pressure or 100 psi, which retreadable .
ever is the lesser . The tire /wheel assembly is then NONRETREADABLE . - Nonretreadable tires
removed from the safety cage , a valve cap are coded for condemnation and forwarded to
installed , and the assembly stored in a rack , the nearest Property Disposal Officer via the
ready for issue. local Supply Department . The following inspec
If there is a significant pressure loss, the tire tion criteria must be used by the tire shop
pressure is reduced to 50 percent of the maxi personnel to determine those tires that are
mum operating pressure , the assembly removed nonretreadable :
253
1. Blowouts. cloth saturated in a soap and water solution .

2. Punctures extending through the entire Rinse well with tap water.
carcass measuring more than 1/4 inch in
diameter /length on the outside and more than Uneven Tread Wear
1/8 inch in diameter/length on the inside.
3. Loose , frayed, or broken cords evident on If a tire shows signs of uneven or excessive
the inner tire surface . tread wear, the cause should be investigated and
4. Cord body fabric damage, visible to the the condition remedied before the tire is ruined.
naked eye without the use of mechanical UNDERINFLATION . - Underinflation causes
devices. the tire to wear rapidly and unevenly at the
NOTE : Exposure of cords on fabric rein outer edges of the tread as shown in figure 9-19.
forced tread tires ( which is imprinted on the tire An underinflated tire develops higher tempera
sidewall ) is permissible. tures during use than a properly inflated tire and
5. Kinked , broken , or exposed wire beads. this can result in tread separation or blowout
6. Tread separation and bulges exceeding 1 type failure.
inch . OVERINFLATION . - Overinflation reduces
7. Tires saturated with rubber deteriorating the tread contact area causing the tire to wear
liquids. faster in the center as shown in figure 9-20.
8. Tires exposed to excessive heat .
RETREADABLE . - All tires removed from

service which are not condemned are potentially
repairable and must be returned to the Supply
Department for retreading. The number of
retreads a carcass may receive will be based
solely on carcass integrity as determined by the
applicable inspection criteria .
PREVENTIVE MAINTENANCE
Debris on the runways and parking areas

causes tire failures and results in many tires
being removed long before giving full life, as a
result of cuts . It is therefore important that such
areas be kept clean at all times .
When ground handling an aircraft, do not
pivot with one wheel locked or turn sharply at
slow speeds, as this not only scuffs the tread off,
but also causes internal separation of the cords.
Always be sure the aircraft is moving before
attempting a turn . This allows the tire to roll
instead of scrape .
Particular care should be observed in prevent
1
ing oil , grease, hydraulic fluid , or other harmful

materials from coming in contact with the tires.
During maintenance, when there is a chance that
harmful materials may come in contact with the
tires, they should be protected by covers. To AM, 1220
clean tires which have come in contact with oil, Figure 9-19 . - Rapid tread wear caused by
grease , or other harmful materials, use a brush or underinflation .
254
AM.1221
Figure 9-20.-Rapid tread wear caused by
overinflation .
Overinflation increases the possibility of damage

to the cord on impact with foreign objects and AM.1222
arresting cables on the runway or flight deck . Figure 9-21. -Rapid tread wear caused by misalignment
MISALIGNMENT. - Figure 9-21 shows rapid
and uneven tire wear caused by incorrect camber
or toe-in . The wheel alignment should be cor off and landing . This makes handling of the
rected in accordance with the applicable aircraft aircraft difficult.
manual to avoid further wear and mechanical
problems.
BALANCE . - Correct balance of the tire, tube, Nylon Flat Spotting
and wheel assembly is important. A heavy spot
on an aircraft tire causes that spot to always hit If the aircraft stands in one place under a
the ground first upon landing , resulting in heavy static load for several days , local stretch
excessive wear at the one spot and an early ing may cause an out-of -round condition with
failure at that part of the tire. A severe case of the resultant thumping during takeoff and land
imbalance causes excessive vibration during take ing.
255
Dual Installations
VENT RIDGES
On dual-wheel installations , tire should be
matched in accordance with dimensions
indicated in table 9-1 . Tires vary somewhat in
size between manufacturers and can vary a great
deal after being used. When two tires are not
matched , the larger one supports most or all of
the load . Since one tire is not designed to carry
this increase in load, a failure may result .
Table 9-1 . - Tolerances for diameters of paired tires in

dual installations.
Tire outside Maximum difference in AM, 1223

diameter outside diameters Figure 9-22 . - Inner tube vent ridges.
Less than 1/8 inch circumference . The reinforcement extends a

18 inches
minimum of 1/2 inch beyond that portion of
18 to 24 inches 1/4 inch the tube which contracts the rim .
25 to 32 inches 5/16 inch Type III inner tubes used at inflation pres
sures above 100 psi , and all type VII inner tubes,
33 to 40 inches 3/8 inch have radial vent ridges molded on the surface, as
41 to 48 inches 7/16 inch shown in figure 9-22, to relieve air trapped
between the casings and the inner tube during
49 to 55 inches 1/2 inch inflation .
56 to 65 inches 9/16 inch Inner tube valves are designed to fit specific
More than 65 5/8 inch wheel rims. However, special valve bending
inches configurations or extensions to provide access to
the valve stem when servicing the tire may be
required.
STORAGE
INNER TUBES
Tubes should be stored under the same
The purpose of the inner tube is to hold the conditions as that outlined for tires. New tubes
air in the tire. Tubes are identified by the type should be stored in their original containers.
and size of the tire in which they are to be used. Used tubes should be partially inflated (to avoid
creasing in storage ), dusted with talc (to prevent
IDENTIFICATION sticking) and stored in the same manner as tires.
Each tube should be plainly marked to identify
Tube types are designated the same as for the contents , size, type, cure date, and stock
corresponding tires in which they are to be used. number. Under no circumstances should inner
For example, a type I tube is designed for use in tubes be hung over nails or hooks .
a type I tire . Tube size is the size of the tire the
tube is designed to fit. INSPECTION
Inner tubes required to operate at 100 psi or
higher inflation pressures are usually reinforced Inner tubes should be inspected and classified
with a ply of nylon cord fabric around the inside as serviceable or nonserviceable. Usually, leaks
256
Chapter 9 - LANDING WHEELS , TIRES, AND TUBES
due to punctures, breaks in the tire , cuts , and the following defects should be classified as
the like, can be detected by the eye, but small repairable :
leaks require a water check. Complete sub
mersion in water is the best way to locate small 1. Bent , chafed, or damaged metal valve
leaks. If the tube is too large to be submerged , threads.
spread water over the entire surface and examine 2. Replaceable leaking valve cores.
carefully for air bubbles. The valve stem and
valve base should be swished around to break NONREPAIRABLE . - Nonserviceable tubes
any temporary seals. The tube should be with the following defects should be classified as
checked for bent or broken valve stems, also for nonrepairable :
stems with damaged threads.
1. Any tear, cut , or puncture which
Serviceable Tubes completely penetrates the tube.
2. Fabric reinforced tubes with blisters
Inner tubes should be classified as serviceable greater than 1/2 inch in diameter in the rein
if they are found to be free of leaks and other forced area .
defects when inflated with a minimum of 3. Chafed or pinched areas caused by beads
nitrogen required to round out the tube and or tire breaks .
then immersed in water . 4. Valve stems pulled out of fabric base type
tubes .
Nonserviceable Tubes 5. Deterioration or thinning due to brake
heat .
Nonserviceable tubes may be repairable or 6. Folds or creases.
nonrepairable. 7. Severe surface cracking.
REPAIRABLE . - Nonserviceable tubes with 8. No balance marker.
257
CHAPTER 10
TUBING, FLEXIBLE HOSE, AND CLAMPS
In this chapter we will discuss rigid tubing, FLUID LINE IDENTIFICATION

flexible hose , and the line clamps that are used
to support and bond rigid tubing to the aircraft Each fluid line in the aircraft is identified by
structure . Modern day aircraft have hundreds of bands of paint or strips of tape around the line
feet of tubing and flexible hose running through near each fitting. These identifying media are
out the wings and fuselage . The AMS is not applied at least once in each compartment.
responsible for maintaining the fluid systems in Various other information is also applied to the
Navy aircraft, but in many instances he is called lines.
upon to assist the AMH and AME in maintaining In most instances, lines are marked by the use
their respective systems. Therefore a knowledge of tape or decals. On lines 4 inches and larger in
of the materials, tools , equipment required, and diameter, lines in an oily environment, hot lines,
the proper procedures to follow in fabricating and on some cold lines, tages may be used in
and installing tubing, flexible hose , and line place of tape or decals.
clamps is necessary . NOTE : On lines in engine compartments,
Many lives have been lost in aircraft accidents where there is the possibility of tapes, decals, or
caused by fluid line and/or fitting failure. The tags being drawn into the engine induction
following quotes are typical of some found in system , the information can be applied as
aircraft accident reports . follows: Type or print (ballpoint pen) the
information on white paper or decal and place it
“ Hydraulic fitting cracked . Probable cause , in position on the tubing. Apply a length of
overtorque of nut during line installation follow clear, heat- shrinkable rubber tubing, MIL
ing system maintenance.” R -46846 type V, over the area, 1 /2 - inch longer
>
than the label.

“ Hole in utility system pressure line. Inves
tigation revealed chafing of pressure line by port Identification tape codes indicate the func
aileron control cable . Cause , support clamp not tion , contents, hazards, direction of flow , and
reinstalled after hydraulic pressure line was pressure in the fluid line . These tapes are applied
replaced following system maintenance, thus in accordance with MIL -STD -1247. This Military
allowing the pressure line to contact the control Standard was issued in order to standardize fluid
cable." line identification throughout the Department
" Flexible hose parted at end fitting. Cause, of Defense. Figure 10-1 illustrates the method of
incorrect end fittings installed during fabrication applying these tapes as specified by this stand
ard .
of replacement hose assembly by maintenance The function of aa line is identified by use of a
personnel.” tape, approximately 1 inch wide, upon which
NOTE : The quotes listed above point out word(s), color(s), and geometric symbols are
just a few different maintenance errors that have printed. Functional identification markings, as
caused or are suspected of causing aircraft provided in MIL -STD -1247, are the subject of
>
accidents . international standardization agreement. Three
258
Chapter 10-TUBING , FLEXIBLE HOSE, AND CLAMPS
CONTENTS
PRESSURE
COMPRESSED AIR PH DAN 3,600 PST

PNEUMATIC
COMPRESSED AIR PH DAN 3000 PSI
ENIDMATA soov.9-22
DIRECTION
HAZARD CODE OF FLOW
IDENTIFICATION
OF FUNCTION
AM.66
Figure 10-1. - Fluid line identification application.
fourths of the total width on the left side of the line identified by the word “ TOXIC ” contains
tape has a code color or colors which indicate materials which are extremely hazardous to life
one function only per color or colors. The or health .
function of the line is printed in English across Anesthetics and harmful materials (AAHM ).
the colored portion of the tape ; therefore, even All materials productive of anesthetic vapors and
a non English -speaking person can troubleshoot all liquid chemicals and compounds hazardous
or maintain the aircraft if he knows the code but to life and property, but not normally produc
cannot read English . The right-hand one -fourth tive of dangerous quantities of fumes, or vapors,
of the functional identification tape contains a are in this category .
geometric symbol which is different for every Physically dangerous materials (PHDAN ). A
function . This is to insure that all technicians, line which carries material which is not danger
whether English speaking or not , who may be ous with in itself, but which is asphyxiating in
colorblind may still be able to positively identify confined areas or which is generally handled in a
the line function by means of the geometric dangerous physical state of pressure or tempera
design rather than by the color(s) or word(s). ture is identified by the marking “ PHDAN .”
Figure 10-2 is a listing, in tabular form , of Table 10-1 lists some of the fluids with which
functions and their associated identification the AMS may be required to work and the
media as used on the tapes. hazards associated with each.
The identification -of-hazards tape shows the
hazard associated with the contents of the line.
Tapes used to show hazards are approximately
one-half inch wide , with the abbreviation of the RIGID TUBING
hazard contained in the line printed across the
tape. There are four general classes of hazards Rigid tubing assemblies are made up mainly
found in connection with fluid lines . These of aluminum alloy or stainless steel tubing.
hazards are outlined in the following paragraphs. However, copper tubing is used in certain parts
Flammable material ( FLAM ). The hazard of some oxygen systems.
marking “ FLAM ” is used to identify all mate Two aluminum alloys are in common use
rials known ordinarily as flammables or alloy 5052 may be used for lines carrying
combustibles. pressures up to 1,500 psi and alloy 6061 for
Toxic and poisonous materials ( TOXIC ). A pressures up to 3,000 psi.
259
FUNCTION COLOR SYMBOL
Fuel Red
Rocket Oxidizer Green , Gray

Rocket Fuel Red , Gray
Water Injection Red , Gray , Red
Lubrication Yellow
Hydraulic Blue , Yellow

Solvent Blue , Brown
Pneumatic Orange , Blue

Instrument air Orange , Gray
Coolant Blue
Breathing Oxygen Green
Air Conditioning Brown , Gray

Monopropellant Yellow , Orange
Fire Protection Brown
De - Icing Gray
Rocket Catalyst Yellow , Green

Compressed gas Orange
Electrical Conduit Brown , Orange

Inerting Orange , Green **
AM.67
Figure 102. - Functional identification tape data .
As a general rule, exposed lines and lines 8 tubing is 8/16 or 1/2; etc. Wall thickness is
subject to abrasion, intense heat, or extremely specified in thousandths of an inch.
high pressures are made of stainless steel. Replacement tubing assemblies should be
Flexible hose is generally used in connection fabricated from the same type materials as the
with moving parts or where a line is subject to original part. Most aircraft Maintenance Instruc
considerable vibration . tions Manuals contain a table of acceptable
substitutes which lists the original material and
TUBING SIZES wall thickness and substitutes with wall thick
nesses for each .
The tubing used in the manufacture of rigid
tubing assemblies is sized by outside diameter TUBE FITTINGS
(OD) and wall thickness. Outside diameter sizes
are in sixteenth -inch increments, the number of Fittings for tube connections are made of
the tube indicating its size in sixteenths of an aluminum alloy , steel, and corrosion -resistant
inch . Thus, No. 6 tubing is 6/16 or 3/8 inch ; No. steel (CRES). Fittings are made in many shapes
260
Chapter 10 - TUBING , FLEXIBLE HOSE, AND CLAMPS
Table 101. -Hazards associated with various fluids.
Contents Hazard
Air (under pressure) PHDAN

Alcohol FLAM
Carbon dioxide SLEEVE
PHDAN
Freon PHDAN NUT
Gaseous oxygen PHDAN TU BING
Liquid nitrogen PHDAN
Liquid oxygen PHDAN
LPG (liquid petroleum gas) FLAM
Nitrogen gas PHDAN
Oils and greases FLAM AM.68
JP - 5 . FLAM Figure 103. - Flared -tube fitting.
Trichlorethylene AAHM
Flareless - Tube Fitiings (MS)
The flareless-tube fitting shown in figure 10-4

consists of a sleeve and a nut. Notice that the
tubing is not flared. (In order to effect a seal
and forms, each designed to fulfill certain between the tubing and the sleeve, an operation
requirements. The following paragraphs cover called presetting is performed which is discussed
two common styles of tube fittings - the flared later in this chapter). The connector has a
(AN ) type and the flareless (MS) type . Also counterbore, a portion of which is beveled 24
covered here is the metal lip -seal fitting, which is degrees. The seat in the connector forms a stop
being used on the A-7 and A4 aircraft. for the tube , and the beveled area causes the
sleeve to seal the connection as the nut is
tightened .
Flared - Tube Fittings ( AN ) There are two types of flareless -tube fittings
in current use . The newer most widely used type
The flared -tube fitting shown in figure 10-3 consists of a long sleeve (MS21922) and short
consists of a sleeve and a nut . The sleeve fits nut . (MS21921). The older type consists of a
directly over the tube, and one end is counter short sleeve (MS21918 ) and a long nut
sunk at the same angle as the tubing flare. The (MS21917 ).
nut fits over the sleeve, and when tightened , Flareless -tube fittings are made of aluminum
draws the sleeve and tubing flare tightly against and steel. The aluminum fittings are identified,
the male fitting ( connector ) to form the seal. visually, by their green and yellow color, which
The male fitting has a cone-shaped surface with is caused from the anodizing treatment. Steel
the same angle as the inside of the flare. The fittings are cadmium plated, which makes their
sleeve supports the tube so that vibration does colors a silvery -white.
not concentrate at the edge of the flare, and
distributes the stresses over a wider area for Metal Lip - Seal Fittings
added strength .
Flared -tube fittings are identified by their Metal lip -seal fittings (unions, reducers, and
color. Aluminum alloy fittings are blue and steel plugs ) are utilized throughout most brazed
fittings are black . tubing type systems. Figure 10-5 illustrates a
261
component . The conventional fitting requires

MS
the use of an O -ring seal. The metal lip -seal
SLEEVE, NUT
SEAT CONNECTOR fittings utilize an integral metal contact seal (fig.
10-5 ).
240 25 When the lip -seal fittings are installed in the
port of a component and properly tightened , the
metal contact seal area provides pressure -assist
type sealing without the use of O - rings. The two
COMPONENTS types of fittings are completely interchangeable;
however, the lip -seal fittings provide better
system integrity because of the absence of
O -rings.
AM.69
Figure 10-4 . - Flareless -tube fittings.
REMOVAL AND REPLACEMENT OF
metal lip -seal plug and union or reducer. These DAMAGED TUBING
fittings are identical in application to the
conventional fluid fitting common to most All tubing is pressure tested prior to installa
AM's. tion and is designed to withstand several times
The major difference between conventional the operating pressure to which it will be
type fluid fittings and the lip -seal type is the subjected. If a tube bursts or cracks, it is
manner in which they form a fluid pressure seal generally the result of excessive vibration,
when installed in the port of a hydraulic improper installation, or from damage caused by
INTEGRAL
METAL - CONTACT
SEAL
UNION OR
REDUCER
PLUG STANDARD
ANOI0050 BOSS
UNION OR REDUCER INSTALLED

IN STANDARD ANOIO 050 BOSS .
AM.933
Figure 10-5 . - Metal lip - seal fittings.
262
Chapter 10-TUBING, FLEXIBLE HOSE, AND CLAMPS
collision with an object. All tubing failures produce a square end, free from burrs. Tubing
should be carefully studied and the cause of the may be cut with a tube cutter or a fine-tooth
failure determined if possible. Replacements hacksaw .
should be of the same size and material as the Correct use of the tube cutter is shown in
original or an acceptable substitute . The ap figure 10-6 . The procedure is as follows: Place
plicable Maintenance Instructions Manual usual the tube in the cutter with the cutting wheel at
ly lists acceptable substitutes for the original the point where the cut is to be made . Tighten
material. the adjusting knob so as to apply light cutter
pressure on the tube , then rotate the cutter
LAYOUT OF LINES toward its open side , as shown in the illustra
tion . As the cutter is rotated about the tube,
A damaged line should be carefully removed continue to apply light pressure to the cutting
so that it may be used as a template or pattern wheel by intermittently tightening the knob.
for the replacement item. If the old piece of Too much pressure applied to the cutting wheel
tubing cannot be used as a pattern, an ac at one time may deform the tubing or cause
ceptable one can be made by placing one end of excessive burrs. After the cut is completed ,
a piece of soft iron wire into one of the fittings remove all burrs inside and outside , then clean
where the tube is to be connected . Form the the tube to make sure no foreign particles
necessary bends in order to place the opposite remain .
end of the wire into the other connection . When If a tube cutter is not available , a fine -tooth
the template satisfactorily spans the area (32 teeth per inch) hacksaw may be used in
between the fittings, it can be used as a pattern cutting tubing. A convenient method of holding
to bend the new tube . tubing when cutting it with aa hacksaw is to place
Select a path with the least total degrees of the tube in a flaring block and clamp the block
bend, as this reduces flow loss and simplifies in a vise. After cutting tubing with aa hacksaw all
bending. Use a path with all bends in the same saw marks must be removed by filing. After
plane, if possible .
Never select a path that requires no bends. A
tube cannot be cut or flared accurately enough
RD
WATE
CUTTING
OPEN
SIDE
so that it can be installed satisfactorily without CUTTER

TOTA
OF
A TUBE
RO
bends . Bends are also necessary to permit the

tubing to expand or contract under temperature
changes and to absorb vibration. If the tube is
small (under 1/4 inch) and can be hand formed ,
casual bends may be made to allow for this. If
WAW
the tube must be machine formed, definite CUT

bends must be made to avoid a straight as
sembly .
Care must be taken to start all bends a
reasonable distance from the end fittings , as the
sleeves and nuts must be slipped back along the TUBE
tube during the fabrication of flares and during

inspections. In all cases, the new tube assembly
should be so formed prior to installing that it is
not necessary to PULL or DEFLECT the as
sembly into alignment by means of the coupling CLEAN CUT
nuts .
TUBE CUTTING
AM.70
The ideal objective, when cutting tubing, is to Figure 10-6 . - Tube cutting.
263
aircraft grade, high -strength, stainless -steel

tubing, as well as all other metal tubing. It is
designed to be fastened to a bench or tripod,
and the base is formed so as to provide a secure
grip in a vise.
АГ TAА The simple hand bender shown in figure 10-8
uses two handles as levers to provide the
mechanical advantage necessary to bend the
tubing , while this type tube bender employs a
handcrank and gears. The forming die is keyed
ECTION A - A to the drive gear and secured by a screw ( fig.
10-9 ).
The forming die on the mechanical tube
AM.71 bender is calibrated in degrees similar to the
Figure 10-7 . – Properly burred tubing. radius block of the hand type bender. A length
of replacement tubing may be bent to a
iling, remove all burrs and sharp edges from the specified number of degrees or it may be bent to
side and outside of the tube as shown in figure duplicate the bend in the damaged tube or
0-7 . Clean out the tube and make sure no pattern. Duplicating the bend of a damaged tube
oreign particles remain . or pattern is accomplished by laying the pattern
on top of the tube being bent and slowly
bending the new tube to the required bend.
'UBE BENDING NOTE : Certain types of tubing are more elastic
than others ; therefore, it may be necessary to
The objective in tube bending is to obtain a bend the tube past the required bend to allow
mooth bend without flattening the tube . Tube for springback .
ending is usually accomplished with one of the
ube benders discussed in this section ; however,
7 case of an emergency , aluminum tubing under TUBE FLARING
14 inch in diameter may be bent by hand .
A hand flaring tool similar to that shown in
land Tube Bender figure 1010 is usually used for single flaring
tubing. This tool consists of a flaring block or
The hand tube bender ( fig. 10-8 ) consists of grip die , a yoke, and a plunger or flaring pin.
our parts - handle, radius block, clip , and slide The grip die consists of two steel blocks hinged
ar handle. The radius block is marked in at one end and held in alignment by a pilot pin.
egrees of bend ranging from 0 to 180. The slide A number of countersunk holes, varying in size
ar handle has a mark which is lined up with the to conform with tube diameters and with
ero mark on the radius block . The tube is countersinks matching standard flare angles and
serted in the tool ; and after lining up the radii, are provided with half of the hole in each
narks, the slide bar handle is moved around block .
ntil the mark on the slide bar handle reaches The yoke fits over the two halves of the grip
he desired degrees of bend on the radius block. die and has a setscrew which is used to lock the
yoke at the desired position . The yoke also
lechanical Tube Bender serves as a centering guide for the plunger. The
plunger is tapered to the same angle as the
The tube bender shown in figure 10-9 is countersunk holes in the grip die.
ssued as a kit . The kit contains the equipment To flare the end of a tube with this tool, slip
Lecessary for bending tubing from 1/4 inch to the fitting nut and sleeve onto the tube and
/4 inch in diameter. place the tube in the proper size hole in the grip
This tube bender is designed for use with die . ( The end of the tube should extend 1/64
264
NOTE : THIS BENDER CAN BE SLIPPED OVER

PARTIALLY CONNECTED TUBES AS IT IS 1 RAISE SLIDE BAR
APPLIED AT DIRECT POINT OF BEND HANDLE UPWARD
RIGHT
HAND
2 PLACE TUBE
TUBE
HANDLE
LEFT HAND
3 PREPARE TO RAISE CLIP OVER TUBE
4 DROP CLIP OVER TUBE NOTE : ZERO MARK COINCIDES

WITH MARK ON BLOCK
TUBE
-081
5 WITH RIGHT HAND, CONTINUE

LEFT HANO
TO BEND TUBE TO DESIRED
ANGLE BY PRESSING SLIDE BAR HANDLE
AS SHOWN BELOW
90
MARK
6 TO REMOVE BENT TUBE,
LIFT SLIDE BAR HANDLE TO
ORIGINAL POSITION AND
RAISE CLIP
TU
BE
RIGHT HAND
‫مرا‬ A BEND OF
90 ° DONE AS
LEFT SHOWN IN ABOVE
HAND STEPS
AM.72
Figure 10-8 . - Tube bending.
inch above the surface of the grip die .) Center with a hammer or mallet. Turn the plunger a
the plunger over the end of the tube and tighten half turn after each blow and make sure it seats
the yoke setscrew to secure the tubing in the properly before removing the tube from the grip
grip die and hold the yoke in place. The flare is die. After completing the flare, inspect to insure
made by striking the plunger several light blows that no cracks are evident.
265
FOLLOW BAR
FORMING DIE
PLUNGER
15%
CRANK
HOOK ROLLER BEARING

SUPPORT ASSEMBLY
AM.73
Figure 10-9 . -Mechanical tube bending tool.
FINISHED DOUBLE
DIE BLOCK FLARE
PLUNGER
YOKE
TOOL BODY
RAM
GRIP DIE
SET SCREW
FINISH FLARE
PUNCH
UPSET FLARE
DIE BLOCKS PUNCH
TUBING
AM.74 AM.75
Figure 10-10 . - Tube flaring tool (single flare). Figure 10-11. - Tube flaring tool ( double flare ).
266
NOTE : The flared end of the tube should not ram lightly until a good seat is formed . Always
be any larger than the largest diameter on the check the seat at intervals during the finishing
sleeve being used. operation to avoid overseating.
Double flares should be used on all 5052
aluminum alloy tubing up to 3 /8-inch diameter. A finished double flare is shown in figure
Steel tubing need not be double flared. The 10-11 .
double flare reduces cutting of the flare by CAUTION : When fabricating oxygen lines,
overtightening and the consequent failure of the insure that all tools are kept free of oil and
tubing assembly under operating pressure. grease .
Aluminum alloy tubing used in low - pressure
oxygen systems should always be double flared. PRESETTING FLARELESS
Figure 10-11 shows one of the tools used in the TUBE FITTINGS
manufacture of double flared tube assemblies.
This flaring tool is issued as a kit. The kit Although the use of flareless -tube fittings
contains a tool body , a ram , and a finish flare eliminates all tube flaring, another operation ,
punch . Also included are a set of die blocks and referred to as PRESETTING , is necessary prior
an upset flare punch for each size of tubing to installation of a new flareless-tube assembly.
which may be flared with this kit. Presetting is necessary to form the seal between
To double flare a tube assembly , prepare the the sleeve and the tube without damaging the
end of the tube as shown in figure 10-7 . Select connector .
the proper size die blocks and proceed as Presetting should always be accomplished
follows: with a presetting tool as shown in figure 10-12.
These tools are machined from tool steel and
1. Place one-half of the die block in the hardened so that they may be used with a
flaring tool body with the countersunk end minimum of distortion and wear. It is recom
towards the ram guide. mended that a mandrel be used during the sleeve
2. Install the nut and sleeve and lay the presetting operation . A mandrel consists of a
tubing in the die block with approximately 1/2 short piece of solid bar of any hard material
inch protruding beyond the countersunk end . such as steel . It should have an outside diameter
3. Place the other half of the die block into of 0.002 to 0.005 inch less than the inside
the tool. Close the latch plate and tighten the diameter of the tube. Using a mandrel assists in
clamp nuts finger tight. attaining an improved sleeve cut during the
4. Insert the upset flare punch in the tool presetting operation. For field use , a short piece
body with the gage end toward the die blocks. of drill rod of the proper diameter may be used
NOTE : One end of the upset flare punch is as a mandrel. The mandrel should be long
counter-bored or recessed to gage the amount of enough to support the tube inside diameter at
tubing needed to form a double lap flare. Insert the sleeve cut and also at the point where the
the ram and tap lightly with aa hammer or mallet sleeve shoulder grips the tube.
until the upset flare punch meets the die blocks NOTE : A connector may be used as a
and the die blocks are firmly set against the stop presetting tool in an emergency . However, when
plate on the bottom of the tool . connectors are used as presetting tools,
5. Tighten the latch plate nuts with aa wrench . aluminum connectors should be used only once
Tighten the nuts alternately , beginning with the and steel connectors should not be used more
closed side to prevent distortion of the tool . than five times. The presetting operation is
6. Reverse the upset flare punch and insert it described in the following paragraphs.
in the tool body . Insert the ram into the tool NOTE : There are two types of flareless -tube
body and tap lightly with a hammer or mallet fittings in current use . The older type consists of
until the upset flare punch contracts the die a short sleeve (MS21918) and a long nut
blocks . (MS21917 ). The newer type consists of a long
7. Remove the upset flare punch and ram . sleeve (MS21922) and a short nut (MS 21921 ).
Insert the finishing flare punch and ram . Tap the The presetting operation for the two types
267
sleeve over the tube, making certain that the
pilot and the cutting edge of the sleeve point
PRESETTING SLEEVE NUT toward the end of the tube . (See fig. 10-12.) If a
TOOL
mandrel is used, it should be inserted in the tube
www at this time .
2. Lubricate the threads of the presetting
tool and the nut with the approved lubricant.
Hydraulic fluid , Specification MIL -H -5606 , is
the approved lubricant for hydraulic lines; and
pneumatic grease, Specification MIL -G -4343, is
the approved lubricant for pneumatic lines.
Refer to NA 01-1 A-20, Aviation Hose Assembly
and Tube Repair, for the approved lubricants for
other systems.
CAUTION : Hydraulic fluid or any other
petroleum base lubricants must not be used as a
thread lubricant for oxygen lines.
3. Place the tool in a vise and hold the tubing
firm and square on the seat in the tool. (The end
of the tube must bottom firmly in the tool.) The
tube should be rotated slowly between the
thumb and fingers while the nut is turned down
SLEEVE PILOT SLEEVE
until the sleeve seizes on the tube . When the
tube no longer turns, the nut is ready for final
ma tightening
4. The final tightening force necessary to set
the sleeve on the tube depends on the type of
fitting. When presetting the older type fittings,
NUT tighten the nut (MS21917 ) 1 1/6 more turns for
PRESETTING TOOL CUTTING EDGE all sizes of tubing and all types of tubing
material. This force sets the sleeve (MS21918 )
on the tube.
SEALING POINTS SPRING WASHER EFFECT
When presetting the newer type fitting - the
long sleeve (MS21922 ) and the short nut
(MS21921 )-the required tightening force varies.
If a mandrel is used, the final tightening force
varies with the size of the tubing. If a mandrel is
not used, the tightening force varies with the
size, wall thickness, and material of the tubing.
Tables of these tightening forces (turn values)
are presented in NA 01-1 A - 20. These tables
AM.76 should be consulted when presetting this type
Figure 10-12. - Presetting flareless -tube assembly . fitting.
The final tightening force permanently as
sembles the sleeve to the tube . Sleeves should
differs to some extent. These differences are not be removed from the tube and reused under
pointed out as applicable in the following any conditions.
discussion . After presetting (fig. 10-13), the nut should
1. Cut the tubing to the correct length , with be uncoupled from the presetting tool , and the
the ends perfectly square . Burr the inside and sleeve and tube inspected for the following:
outside of the tube. Slip the nut and then the 1. The sleeve cutting lip should be embedded
268
4. The sleeve should be slightly bowed and

rotation of the sleeve is permitted . A 1 /64 -inch
SLEEVE PILOT
SLEEVE lengthwise movement of the sleeve is also
X permitted .
5. As a final check to determine that the
HEZ TUBE
fitting is properly preset , it should be proof
tested at a pressure equal to twice the intended
working pressure .
INSTALLATION OF
TUBE ASSEMBLIES
AM.703 Before a tubing assembly is installed in an

Figure 10-13 . - Preset sleeve - flareless- tube fitting. aircraft, it should be carefully inspected . Dents
and scratches should be removed (if possible
without weakening the tube) prior to installa
into the tube outside diameter approximately tion . The proper nuts and sleeves should be
0.003 to 0.008 inch (distance (X ) in figure installed and a proper fit obtained where the
10-13), depending on the size and material of tubing is flared . Flareless assemblies should be
the tubing. As shown, a lip of material will be
> checked for proper presetting. Each tube as
raised under the pilot. The pilot of the sleeve sembly should be proof pressure tested to twice .
should contact or be quite close to the outside its operating pressure prior to installation. The
diameter of the tube . (See distance ( Y ) .) The tubing assembly should be clean and free from
tube projection from the pilot of the sleeve to all foreign matter.
the end of the tube (distance (Z )) should be The nuts should be hand screwed to the mating
approximately as listed in table 10-2 . These connector, then tightened with the proper
figures will vary with wall thickness for a given wrench . The tubing assembly should not have to
size . be pulled into place with the nut , but should be
2. A slight collapse of the inner diameter of properly aligned prior to tightening.
the tube at the sleeve cut and at the shoulder is Tubing which runs through cutouts should be
permissable. installed with care so that it will not be scarred
3. The sealing surface of the sleeve must be when worked through the hole . If the tubing
smooth and free from nicks and scratches. assembly is long, the edges of any cutouts
should be taped before the tubing is installed .
Table 10-2 . - Distance from sleeve to tube end . It is important to tighten tube fitting nuts
properly . A fitting wrench or open end wrench
should be used when tightening tube con
nections. NOTE : Pliers should never be used to
tighten tube connections.
Tube size Approximate tube projection
(inches) Flared - Tube Assemblies
3/16 7/64 Correct and incorrect methods of installing

1/4 7/64 flared - tube assemblies are illustrated in figure
5/16 5/32 10-14 . Proper torque values are given in tables
3/8 11/64 10-3 and 10-4 . It must be remembered that
1/2 3/16 these torque values are for flared -tube fittings
5/8 13/64 only.
3/4 7/32 If an aluminum alloy tube assembly leaks
1 15/64 after tightening to the required torque , it must
not be tightened further. Overtightening may
severely damage or completely cut off the
269
DO NOT DEFLECT INTO PLACE;

REPLACE TUBE ASSEMBLY
INCORRECT – WILL DAMAGE

FLARE OR THREADS, OR CAUSE
SLEEVE TO CRACK ' UNDER
VIBRATION OF TIGHTENED
INCORRECT - MAY PULL OFF OR

-
DISTORT FLARE IF TIGHTENED
CORRECTLY FITTED
AND TIGHTENED
0.025 CLEARANCE BETWEEN

FLARE AND SHOULDER
BEFORE TIGHTENING
AM.77
Figure 10-14. -Correct and incorrect method of installing flared fittings.
tubing flare or may result in damage to the CAUTION : A nut should never be tightened
sleeve or nut . The leaking connection should be when there is pressure in the line, as this will
disassembled and the fault corrected . Common tend to damage the connection without adding
faults are as follows: any appreciable torque to the connection.
1. Flare distorted into the nut threads .
2. Sleeve cracked . Flareless - Tube Assemblies
3. Flare out of round .
4. Flare cracked or split . When installing flareless -tube assemblies,
5. Inside of flare rough or scratched . inspect to insure that no scratches or nicks are
6. Connector mating surface rough or evident and that the sleeve is properly preset.
scratched . Lubricate the threads of the nuts and con
7. Threads of connector or nut dirty , nectors with hydraulic fluid . Place the assembly
damaged , or broken. in the proper position in the aircraft and finger
If a steel tube assembly leaks, it may be tighten clamps, brackets, supports, and nuts.
tightened 1/6 tum beyond the noted torque in The tubing ends should fit snugly in the con
an attempt to stop the leakage ; then if unsuc nectors and require little pressure to hold them
cessful, it must be disassembled and repaired. in place .
Undertightening of connections may be CAUTION : Hydraulic fluid must not be used
serious, as this can allow the tubing to leak at to lubricate fluid line connections in oxygen
the connector because of insufficient grip on the systems.
flare by the sleeve. The use of a torque Wrench Use the torque values listed in table 10-5
will prevent undertightening. whenever possible while tightening flareless nuts.
270
Chapter 10 - TUBING , FLEXIBLE HOSE , AND CLAMPS
>
Table 10-3 . - Torque limits for flared tube fittings.
Torque For AN818 Nut

( inch -pounds)
Tubing outside Aluminium Alloy Tubing Steel Tubing

Diameter Flare AND 10061 or AND 10078 Flare AND10061
(inches) With Aluminium Nuts With Steel Nuts
Min Max Min Max
1/8 20 30 75 85
3/16 25 35 90 100
1/4 40 65 135 150
5/16 60 80 180 200
3/8 75 125 270 300
1/2 150 250 450 500
5/8 200 350 650 700
3/4 300 500 900 1000
1 500 700 1200 1400
1-1 /4 600 900 1500 1800
1-1 / 2 600 900 2000 2300
1-3 /4 750 1050 2600 2900
2 800 1100 3200 3600
Table 10-4 . - Torque values for double flared type be impossible to run the nut down with the
coupling nuts (oxygen system fittings) . fingers, use a wrench, but be alert for the first
signs of bottoming. It is important that the final
tightening commence at the point where the nut
just begins to bottom .
Tube OD
With a wrench, turn the nut 1/6 turn (one flat
Torque
on a hex nut). Use a wrench on the connector to
(inch) ( inch - pounds)
prevent it from turning while tightening the nut.
Working torque Maximum torque After the tube assembly is installed, the system
should be pressure tested. Should a connection
5/16 100 125 leak , it is permissible to tighten the nut an
additional 1/6 turn (making a total of 1/3 turn ).
3/5 200 250 If, after tightening the nut a total of 1/3 turn ,
leakage still exists, the assembly should be
1/2 300 400 removed and the components of the assembly
inspected for scores, cracks , presence of foreign
material, or damage from overtightening.
NOTE : Overtightening a flareless- tube nut

If it is not possible to use a torque wrench, use drives the cutting edge of the sleeve deeply into
the following procedure for tightening nuts. the tube , causing the tube to be weakened to the
Tighten the nut be hand until an increase in point where normal in -flight vibration could
resistance to turning is encountered . Should it cause the tube to shear. After inspection (if no
271
Table 10-5 . - Torque values for flareless fittings.
WRENCH TORQUE FOR 304 1/8 H STEEL TUBES

Tube Wrench torque
outside diameter Wall thickness inch - pounds
3/16 0.016 90-110

3/16 0.020 90-110
1/4 0.016 110-140
1/4 0.020 110-140
5/16 0.020 100-120
3/8 0.020 170-230
3/8 0.028 200-250
1/2 0.020 300-400
1/2 0.028 400-500
1/2 0.035 500-600
5/8 0.020 300-400
5/8 0.035 600-700
5/8 0.042 700-850
3/4 0.028 650-800
3/4 0.049 800-960
1 0.020 800-950
1 0.065 1600-1750
WRENCH TORQUE FOR 304-1A or 3471A STEEL TUBES
3/8 0.042 145-175

1/2 0.028 300-400
1/2 0.049 500-600
1 0.035 750-900
WRENCH TORQUE FOR 6061 -T6 or T4 TUBES

1/4 0.035 110-140
3/8 0.035 145-175
1/2 0.035 270-330
1/2 0.049 320-380
5/8 0.035 360-440
5/8 0.049 425-525
3/4 0.035 380-470
1 0.035 750-900
1 1/4 0.035 900-1100
discrepancies are found), reassemble the con Brazed Hydraulic

nections and repeat the pressure test procedures. Tube Assemblies
CAUTION : Do not in any case tighten the
nut beyond 1/3 turn (two flats on the hex nut ); Brazed hydraulic tubing systems are appearing
this is the maximum the fitting may be in many of the later model aircraft within the
tightened without the possibility of permanently Navy. The brazed hydraulic tubing system
damaging the sleeve and tube . includes a multi-branch feature which results in
272
BRAZE ALLOY
FILLER
TEE
-TUBING
TEE
-TUBING
( A)
NUT AND SLEEVE

( TYP )
(A)
AM.932
Figure 10-15 .-- Brazed hydraulic tubing assembly.
fewer threaded connections and the near tion are covered in Structural Hardware, NavAir
elimination of O -ring seals . A typical example of 01-1A-8 .
a brazed hydraulic assembly is provided in figure Overtightening of the B-nut on the flareless
10-15 . Brazed tubing assemblies are made of type fitting used to connect most brazed tubing
rigid corrosion -resistant steel and assembled with assemblies usually results in damage to the sleeve
sleeves and coupling nuts. Individual segments of and consists of a necking down or swagging of
the assembly are generally identified by separate the tip. This necking down can usually be
part number and dash number and are brazed corrected by the use of a sleeve sizing punch
together into an assembly . On some aircraft such assembly as illustrated in figure 10-16 . Because
as the A -4F , a direction -of-flow arrow is of the malleability of the sleeve material, sizing
>
electroetched on each individual segment of can be accomplished several times before the
each tube assembly . prospect of material failure would require re
Maintenance of brazed tubing is limited to placement of that segment.
identification marking maintenance, sleeve SLEEVE SIZING . - The sleeve sizing proce
sizing, segment repair, or complete assembly dure can be accomplished without removing the
replacement. Tubing identification maintenance line assembly from the aircraft, space permit
consists of installing color band tape on new ting. The tube assembly is disconnected and
tubing assemblies and on existing assemblies drained, then the end of the tubing assembly to
where the color bands have become lost , worn , be sized and the threaded body on the punch
. or illegible. The requirements, location , and assembly are lubricated with hydraulic fluid .
precautions for installing color band identifica Connect the B -nut on the end of the tube
273
NUT CAP BODY PUNCH openings on the tube assembly except two, one
B - NUT at the highest and one at the lowest openings.
SLEEVE Pour solvent ( P - D -680 ) into the highest opening
to remove all hydraulic residue. Connect 20 to
TUBE
40 psi of air pressure upstream of any cutting,
SLEEVE AND TUBE WALL
burring, and sleeve presetting operations and
COLLAPSED insure that the coupling downstream is open for
PUNCH RETRACTED
purge air exit. This will prevent entry of metal
particles in the hydraulic system . The proce
dures for repair of such tubing assemblies may
NUT CAP BODY B - NUT
PUNCH
vary slightly in the various MIM's . Following
SLEEVE repair, the assembly must be tested.
TUBE
Oxygen System Tube Assemblies
SLEEVE AND TUBE WALL
COLLAPSED Care must be taken at all times to keep the
tubing clean and free of foreign matter during
PUNCH EXTENDED
installation . Thread antiseize compounds and
tapes should not be used on flared tubing fitting
threads. Antiseize tape (MIL - T - 27730A ) may be
AM.934 used on tapered pipe fitting threads.
Figure 10-16 . - Sleeve sizing - flareless fitting. Pipe threaded fittings should be started by
hand. A torque Wrench should be used to
tighten all pipe threaded fittings. The torque
assembly to the threaded part of the body on values for pipe threaded fittings are listed in
the punch assembly fingertight. Using a wrench table 10-6 .
to hold the body , tighten the B-nut 1/6 turn CAUTION : The importance of the following
(one hex side) beyond fingertight . Next , still cannot be overemphasized : It is imperative that
holding the body of the punch assembly , slowly all oxygen equipment, lines, and fittings be kept
turn the cap on the punch assembly until the free from GREASE, DIRT, OIL , HYDRAULIC
punch is bottomed in the extended position . FLUID, AND LEAKS . Leakage in oxygen sys
Reverse the wrench action to withdraw the tem connections should be eliminated since the
punch . Disconnect the punch assembly from the leakage rate may increase with time and vibra
tube assembly and inspect the sleeve. Slight tion .
collapse of the tube assembly is permissible. No
nicks or scoring marks are allowed on the sleeve,
and no movement of the sleeve except rotation FLEXIBLE HOSE
is permissible. Pressure test the repaired as
sembly for leakage as specified in the applicable Flexible hose is used in connecting moving
MIM . If the pressure test is positive , reconnect parts with stationary parts and in locations
the tube assembly to the aircraft system , air subject to severe vibration . It is heavier than
bleed the lines, and service the hydraulic system . aluminum alloy tubing and deteriorates rapidly ;
SEGMENT REPAIR . -Whenever a segment or therefore, it is used only where absolutely
a fitting of a brazed tubing assembly has been necessary . The two types, rubber and Teflon
damaged , it can generally be repaired. Figure flexible hose , are discussed in the following
10-17 provides an example of typical segment paragraphs.
repairs to a damaged assembly. With all pressure
relieved in the system to be repaired, disconnect RUBBER
all couplings. Cap or plug all openings on
adjacent lines and components to prevent loss of Flexible rubber hose consists of a seamless
fluid and contamination . Cap or plug all synthetic rubber inner tube covered with layers
274
Chapter 10- TUBING , FLEXIBLE HOSE , AND CLAMPS
DAMAGE DAMAGE TO
BRAZED TEE
DAMAGE TO
BRAZED TEE
DAMAGE TOO CLOSE

TO BRAZED TEE FOR
SPLICE REPAIR
BRAZED TUBE
ASSEMBLY
DAMAGE
EXISTING FITTING
EXISTING TUBE
TYPICAL DAMAGE AREAS
ASSEMBLY
REWORKED TUBE ASSEMBLY

NEW FITTING NEW FITTING ASSEMBLY
NEW FABRICATED TUBE
SPLICE ASSEMBLY
NEW FITTING
NEW FITTING

REWORKED TUBE ASSEMBLIES
NEW FITTING
EXISTING FITTING
-NEW FABRICATED TUBE

SPLICE ASSENBLY
REWORKED TUBE ASSEMBLY TYPICAL REPAIR AREAS
AM.935
Figure 10-17 . - Brazed tubing segment repair.
of cotton braid and wire braid , and an outer hose which is commonly used in medium
layer of rubber impregnated cotton braid. It is pressure applications. This hose is identified by a
provided in low -pressure, medium -pressure, and Military Specification number, the hose size , the
high -pressure types. Figure 10-18 illustrates the quarter year and year of manufacture , and the
275
Table 10-6 . - Torque values for pipe threaded fittings fittings and are fabricated only by commercial
( oxygen system ). activities and intermediate or depot maintenance
level activities, because of the special tools
required . Medium -and low -pressure hose as
semblies are equipped with detachable type end
Torque ( inch -pounds) fittings ( described later) and may be fabricated
at the intermediate maintenance level.
Pipe thread
(inch) Minimum Maximum FABRICATION AND REPLACEMENT
1/8 40 150 Flexible hose must be replaced if peeling,

1/4 60 200 flaking of the hose cover, or exposure of the
:
3/8 100 400 fabric reinforcement to the elements occur.
When failure occurs in a flexible hose
equipped with swaged end fittings, the unit is
generally replaced without attempting a repair;
that is, the correct length of hose, complete with
hose manufacturer's symbol . This information is factory -installed end fittings, is drawn from
stenciled on the hose at intervals of not more supply .
than 9 inches the entire length of the hose. The When failure Occurs in low -pressure or
stenciled information indicates the natural lay of medium-pressure hose equipped with detachable
the hose . type end fittings, the replacement unit is usually
The size of flexible hose is determined by the fabricated by the AIMD. Undamaged end fit
inside diameter (ID) and indicated by a number tings on the old length of hose may be removed
ing system identical to that used with rigid and reused ; otherwise , new fittings must be
tubing. Therefore, the fittings used on No. 6 drawn from supply along with a sufficient length
hose will be the same size and have the same of hose .
threads as those used on No. 6 (3/8 inch) tubing. NOTE : Inspect bulk hose prior to use to
High -pressure hose is available to the insure that its shelf life has not expired .
operating activity in complete assemblies only. Figure 10-19 illustrates one type of de
These assemblies are equipped with swaged type tachable end fitting. This fitting is intended for
TWO COTTON BRAIDS - IMPREGNATED

WITH SYNTHETIC COMPOUND
MIL-H - 8794-Size-6-2/68 -Mig Symbol

YELLOW SINGLE WIRE BAND
SYNTHETIC RUBBER INNER TUBE
AM.79
Figure 1018. -Medium -pressure hose .
276
Chapter 10-TUBING, FLEXIBLE HOSE, AND CLAMPS
SOCKET NIPPLE NUT
MUHJAUTUMIK O
ASSEMBLED
FITTING
PART NO. 597

AM.80 ASSEMBLY TOOL KIT
Figure 10 19. - Sleeve type flexible hose fitting ( SIZES —3 THRU 12 )
(MS -24587 ).
AM.81
use with medium -pressure hose which conforms Figure 10-20 . -Medium -pressure hose assembly tool kit.
to Specification MIL - H -8794. This fitting is
designed for use in flared -tube systems . Other
hose fittings which are designed to be used with instructions contained in the applicable Mainte
flareless -tube fittings are also available. nance Instructions Manual . In cases where proof
test pressures are not included in the aircraft
Assembly of Sleeve Type Fittings Maintenance Instructions Manual, refer to Avia
tion Hose Assembly and Tube Repair, NavAir
A tool kit is available for assembling the 01-1 A-20. Table 10-7 lists the prooftest pressure
MS-24587 fittings to MIL -H -8795 (medium for a few sizes of medium -pressure (MIL - H
pressure ) hose . Figure 10-20 illustrates the hose 8795 ) hose when assembled with MS-24587
assembly tool kit , which contains the assembly
> fittings for use in aircraft hydraulic systems.
tools for use on the smaller sizes (3/16 through
3/4 inch ) of hose. If a tool kit is not available,
the corresponding size AN -815 adapter may be Installation of Flexible
used . Hose Assemblies
Figure 10-21 illustrates the steps in as
sembling the MS-24587 fitting, using the proper Flexible hose must not be twisted on installa
size assembly tool from the hose assembly tool tion , since this reduces the life of the hose
kit . considerably and may cause the fittings to
After assembly , always make sure all foreign loosen as well. Twisting of the hose can be
matter is removed from the inside of the hose by determined from an identification stripe running
blowing out with compressed air. along its length, or as in the case of medium
All shop-assembled flexible hose must be pressure hose ( shown in figure 10-18 ) by the
proof tested after assembly . Proof testing is stenciled information that is used to identify the
accomplished by plugging or capping one end of hose .
the hose and applying pressure to the inside of The minimum bend radius for flexible hose
the hose assembly. 1 varies according to size and construction of the
Proof testing of shop fabricated hose assem 1
hose and the pressure under which the hose will
blies should be accomplished in accordance with operate. Tables and graphs showing minimum
277
co
✓
( A) (B) ( C)
(D) (E)
AM.82
A. Clamp the hose in the vise and cut the required end exposed. Lubricate the inside of the hose and the
length with a fine tooth hacksaw. nipple threads with hydraulic fluid or light lubricating
B. Secure the socket in the vise. Turn the hose oil .
counterclockwise into the socket until it bottoms. E. Using a wrench on the assembly tool, screw the
Unscrew 1/4 turn . nipple into the socket and hose. Excercise care to
C. Insert the nipple in the nut. Install the proper prevent the hose from turning. A clearance of 1/32 to
size assembly tool and tighten , using two wrenches. 1/16 inch between the nut and socket is required so that
D. Place the socket in the vise with the threaded the nut will swivel. Remove the assembly tool.
Figure 10-21. - Assembly of MS- 24587 fitting to medium -pressure flexible hose .
Table 10-7. -Proof test pressures for medium-pressure hose assembled with MS - 24587 fittings.
Hose size Operating pressure Proof pressure Burst pressure

number (psi) (psi) (psi)
4 3,000 6,000 12,000
5 3,000 5,000 10,000
1
os
6 2,000 4,500 9,000

8 2,000 4,000 8,000
10 1,750 3,500 7,000
12 1,500 3,000 6,000
278
bend radii for all types of installations are support enough to prevent bending and kinking.
provided in Aviation Hose Assembly and Tube 4. Do not permit flexible hose to impinge on,
Repair, NA -01-1 A -20. Bends which are too and thus possibly deflect, rigid supporting lines.
sharp will reduce the bursting pressure of 5. Allow a slight slack in the hose line to
flexible hose considerably below its rated value . accommodate changes in length that will occur
Flexible hose should be installed so that it when pressure is applied .
will be subject to a minimum of flexing during 6. Do not straighten a bent hose that has
operation. Hose must be supported at least every taken a permanent set.
24 inches. Closer supports are desired. 7. Do not hang, lift, or support objects from
A flexible hose must never be stretched tight Teflon hose .
between two fittings. About 5 to 8 percent of its Maintenance
total length must be allowed as slack to provide
freedom of movement under pressure. When Teflon hose , like all aircraft parts , has definite
under pressure, flexible hose contracts in length wearability limits. The chafing caused by hose
and expands in diameter. rubbing against other surfaces, for instance, has
undermined many parts and systems. Disaster
TEFLON consequent to such wear can be averted only
Teflon hose is a flexible hose designed to through frequent inspection and maintenance by
meet the requirements of higher operating alert maintenance and quality assurance person
nel .
temperatures and pressures in present-day
INSPECTION.- Whereas all rubber aircraft
weapon systems. Teflon hose can generally be
used in the same manner as rubber hose . hose must be inspected for aging and associated
Teflon hose consists of a tetrafluorethylene deterioration immediately prior to installation ,
resin which is precessed and extruded into tube Teflon hose, being comparatively inert, is
shape to a desired size . It is covered with exempt from shelf -life control. However, Teflon
stainless steel wire which is braided over the hose assemblies must be visually inspected for
tube for strength and protection . The advantages leakage , abrasion, and kinking according to the
of this hose are its operating temperature range aircraft inspection requirements in the ap
( -67° F to + 450° F ), its chemical inertness to all plicable Maintenance Instructions Manuals . The
presence and extent of the following possible
fluids normally used in hydraulic and engine
lubrication systems, and its long life. At this defects must be determined.
Kinking. – Kinking is an imperfection induced
time, only medium-pressure and high -pressure in Teflon when it is bent at a closer angle (or
types are available and are complete assemblies
shorter radius) than its characteristics allow .
with factory -installed end fittings. These fittings
may be either the detachable type or the swaged This is a common cause of failure, because
type. When failures occur, replacement must be Teflon hose tends to assume the shape of the
made on a complete assembly basis. position in which it is installed and becomes
The size of Teflon hose is determined in the semipermanently set or “ preformed ” in these
same way the size of rubber hose is determined . configurations. These so - called preformed hoses
Teflon hose , like rubber hose , has definite kink easily and their walls are severely weakened
limits and particular characteristics that demand if they are excessively bent or twisted or if they
are permitted to follow their natural tendencies
understanding and attention in the general han
dling during installation and removal. To insure to revert to their orientations. They must be
its satisfactory function and reduce the likeli handled very carefully while being removed and
should be tied with wire that will hold them in
hood of failure , the following rules should be
observed when working with Teflon hose : shape pending reinstallation.
Excessive Cold Flow . - Cold flow is the name
1. Do not exceed recommended bend limits. given the deep permanent impressions and
2. Do not exceed twisting limits. cracks in the hose cover caused by the pressure
3. Clamp the hose assemblies at least every of the hose clamps. Replace hose when cold
24 inches (more closely if possible) to lend flow becomes too deep .
279
Weather -Checking . - Weather -checking, the oc Separation of Outer Cover . - When the cotton
currence of numerous fine cracks caused braid or rubber coverings of metal-reinforced
by exposure to various weather conditions hose become loose, frayed , or chafed to the
over extended periods, causes no serious dam point that the metal reinforcement is exposed or
age as long as it does not expose the fabric of damaged , replace the hose . If a hose shows some
the hose cover. However, weather-checking wear but the metal is not exposed or damaged,
deepened to the point of exposing this fabric wrap the frayed or chafed areas in flexible,
can contribute to the weakening and eventual electrical-insulation sleeving and secure it over
failure of hose . the hose with support clamps.
To examine the extent of weather -checking, Wire-Braid Damage . - Wire -braid damage is
flatten the walls of the hose together, with force considered excessive when two or more wires in
if necessary . If the cord fabric can be seen at any a single plait or six or more in an assembly (or
point , replace the hose . Replace the hose also if lineal foot when assemblies are longer than 12
radial cracks at the end of the hose are deeper inches) are broken . Broken wires, where kinking
than one -eighth inch or are halfway from the of Teflon hose is suspected , are felt as sharp
ends of the hose to the clamps . dents or twists in the braid .
Internal Cracking . - Fuel hoses , both Teflon CAUTION : When performing wire -braid
and rubber , dry out and crack when they lose damage check , the Teflon hose must always be
the placticizer that keeps them pliable. Hoses handled with great care so that the wire -braid
remain pliable while in active use with gasoline damage does not injure the hands.
flowing through them but lose their plasticizers CLEANING . - Teflon hose is nonabsorbent
when the fuel is drawn off. and nonadhesive, and is usually unaffected by
Therefore, fuel lines of previously used air fuels, lubricating oils, coolants, and solvents
craft that are to be returned to service after used around aircraft. It is easily cleaned in
extended storage must be inspected for internal oleum spirits, kerosene, trichlorethylene , or
cracking. Those showing internal cracks, which synthetic detergents. When dipped in or flushed
are best revealed by pressing the hose with the with the cleaning solution , the hose merely
fingers to widen imperfections, should be re needs a slight brushing to remove the surface
placed , while those showing no visible cracks at debris.
either end are considered satisfactory through WARNING : Because some solvents are highly
out . flammable and some toxic, proper precautions
D
BULKHEAD
U
FITTINGSZ CLAMP BLOCK , LINE CLAMPS

V
i
t
a
i
n
AM.415
Figure 10-22 . —Methods used to secure fluid lines.
280
Chapter 10 -TUBING , FLEXIBLE HOSE , AND CLAMPS
must be taken when they are used . Prolonged

inhalation of fumes must be avoided .
STORAGE . -When storing Teflon hose , be
sure to :
1. Cap or plug the ends ofall hose assemblies

with metal or plastic plugs.
2. Tape hose ends to prevent wire flareout.
3. Store hose in straight position if possible .
When it is necessary to coil hose , use the widest
coil possible .
BONDING CLAMPS
CLAMPS
As stated earlier in this chapter there are

hundreds of feet of tubing and flex hose running
throughout the aircraft structure. These fluid
lines are routed to follow the configuration of
the aircraft structure to provide support for the
lines. Clamps, bulkhead fittings, clips, brackets,
and clamp blocks not only secure the lines to
the adjacent structure, but also provide a
dampening effect to prevent harmful vibration .
Fluid lines must be kept separated from the
aircraft structure and other lines to prevent
chafing. Chafing ( rubbing) of the lines can cause
failure of the system . As the lines rub against
each other or the aircraft structure , the wall
thickness of the tubing is diminished until it can CLAMPS ( CUSHIONED )
SUPPORT
no longer withstand the fluid pressure, and the
line ruptures. The three most common methods
of securing fluid lines are shown in figure 10-22 . AM.78
Figure 10-23. - Bonding and support clamps.
INSTALLATION OF CLAMPS
While performing maintenance actions the
AMS may be required to remove clamps and / or Support clamps should be installed at 15 -inch
clamp blocks . In all cases, unless directed by intervals and as close to tubing bends as possible .
Aircraft Changes, Bulletins, etc. , the clamp(s) In no case should clamps be installed at intervals
and /or clamp block (x) with all of the necessary greater than 20 inches.
hardware (washers, spacers, nuts, screws and/or When tubing is supported to a structure or
bolts) must be reinstalled . other rigid member, a minimum clearance of
CAUTION : Do not allow any dropped hard 1/16 inch must be maintained with the structure
ware to remain lying in the aircraft upon or member. A minimum clearance of 1/4 inch
completion of maintenance actions. must be maintained between the tubing and
The most abused and neglected are the line adjacent rigid structure or moving components.
clamps which are used to properly bond Extra support clamps may be used in any
(provide a path for static electricity ) and sup installation to prevent vibration and chafing, or
port rigid tubing and flexible hose . Figure 10-23 to provide line clearance .
shows both the plain bonding clamps and the Figure 10-24 illustrates six ways to secure
cushioned steel clamp. The cushioning material fluid lines to each other using support clamps to
may be either rubber or Teflon . maintain line clearance and prevent chafing due
281
SPACER
ADAPTER
(A) (B ) (C )
தான்
EG
G
ers
wern
( 0) (E) ( F)
AM.416
Figure 10-24 . - Securing lines using support clamps.
to vibration . In view (A) an adapter is used to fluid lines properly .

maintain the desired line clearance. View ( B) Figure 10-25 shows a flexible hose secured to
illustrates the use of a spacer, and views (C), (D) , the aircraft structure. The lower view shows
(E) , and ( F) show the use of support clamps what could happen if too large a clamp were
positioned in such a manner as to separate the used .
282
Chapter 10 -TUBING , FLEXIBLE HOSE , AND CLAMPS
RIGHT
WRONG
ABRASION
CLAMP TOO LARGE
ABRASION
AM.417
Figure 10-25 . - Installation procedures ( right and wrong ).
283
CHAPTER 11
CORROSION CONTROL
CORROSION tion of relatively pure metal from its ore and the
addition of other elements (either metallic or
Modern high -speed aircraft are dependent nonmetallic ) to form alloys. Alloying consti
upon the structural soundness of the metals tuents are added to base metals to develop a
which make up the largest percentage of their variety of useful properties. For example , in
thousands of parts. The greatest threat to aircraft structural applications, high strength - to
structural integrity of naval aircraft is metals weight ratios are the most desirable properties in
corrosion. With higher strength demands being all alloys.
made of aircraft metals and the closer tolerances After refining, regardless of whether or not
of flight safety demanded , these aircraft would alloyed, base metals possess a potential or
rapidly become inoperative without regular anti tendency to return to their natural state . How
corrosion attention . ever , potential is not sufficient in itself to
Corrosion endangers the aircraft by reducing initiate and promote this reversion. There must
the strength and changing the mechanical also exist a corrosive environment, in which the
characteristics of the materials used in its significant element is oxygen . It is the process of
construction . Materials are designed to carry oxidation - combining with oxygen-that causes
certain loads and withstand given stresses as well wood to rot or burn and metals to corrode.
as to provide an extra margin of strength for Control of corrosion is dependent upon main
safety. Corrosion can weaken the structure taining a separation between susceptible alloys
thereby reducing or eliminating this safety and the corrosive environment. This separation
factor. Replacement or reinforcement opera is accomplished in various ways. A good intact
tions are costly, time-consuming, and reduce coat of paint provides almost all of the corrosion
usage of the aircraft. Severe corrosion can cause protection on naval aircraft. Sealants are used at
failure of parts or systems which is an obvious seams and joints to prevent entry of moisture
danger. Corrosion in vital systems can cause into the aircraft; preservatives are used on
malfunctions that endanger the safety of flight, unpainted areas of working parts; and shrouds,
and such dangers reemphasize the importance of covers, caps, and other mechanical equipment
corrosion control. provide varying degrees of protection from
Metals corrosion is the deterioration of metals corrosive media. None of these however, provide
as they combine with oxygen to form metallic 100 percent protection in the long run - paint is
oxides. This combining is a chemical process subject to oxidation and decay through weather
which is essentially the reverse of the process of ing; sealants may work out by vibration or else
smelting the metals from their ores. Very few be eroded by rain and windblast. Preservatives at
metals occur in nature in the pure state . For the best offer only temporary protection when used
most part they occur naturally as metallic on operating aircraft and the mechanical cover
oxides. These oxides may also be mixed with ings are subject to improper installation and
other undesirable impurities in the ores. The neglect . Control of corrosion properly begins
refining processes generally involve the extrac with an understanding of the causes and nature
284
Chapter 11 - CORROSION CONTROL
primarily to avoid the establishment of the

electrical circuit, or secondly , to remove it as
ELECTROLYTE
( FRESH OR SALT WATER , soon as possible after establishment before
GREASE ,DIRT,ETC. ) , serious damage can result. Figure 11-1 illustrates
the electron flow in a corrosion environment
(electrolyte ) resulting in destruction of the
anodic area . Note that the surface of a metal ,
especially alloys of the metal, may contain
anodic and cathodic areas due to impurities or
alloying constituents which have different
ELECTRON FLOW potentials than the base metal .
ANODIC CATHODIC Electrochemical attack is evidence in several
AREA AREA
forms, depending upon the metal involved , its
size and shape, its specific function , atmospheric
conditions, and the type of corrosion -producing
METAL agent (electrolyte) present. There are many
forms of metals deterioration resulting from
electrochemical attack about which a great deal
is known. But despite extensive research and
experimentation , there is still much to be
AM.49 learned about other, more complex and subtle
Figure 11-1 .-Simplified corrosion cell. forms. Descriptions are provided later in this
chapter for the more common forms of
of this phenomenon . Corrosion is caused by corrosion found on airframe structures.
electrochemical or direct chemical reaction of a Since there are so many factors which con
metal with other elements . In the direct tribute to the process of corrosion, selection of
chemical attack , the reaction is similar to that materials by the aircraft manufacturer must be
which occurs when acid is applied to bare metal. made with weight versus strength as a primary
Corrosion in its most familiar form is a reaction consideration and corrosion properties as a
between metal and water and is electrochemical secondary consideration . In the interest of aero
in nature . dyanmic efficiency , even the number of drain
In the electrochemical attack , metals of dif holes is limited until accumulated operational
ferent electrical potential are involved and they data indicates a greater drain requirement. Close
need not be in direct contact . When one metal attention during aircraft design and production
contains positively charged ions and the other is also given to heat treating and annealing
negatively charged ions and an electrical procedures, protective coatings, choice and ap
conductor is bridged between them , current plication of moisture barrier materials, dissimilar
with flow as in the discharge of a dry cell metals contact , and access doors and plates. In
battery . In electrochemical corrosion the other words, every logical precaution is taken by
conductor bridge may be any foreign material the aircraft manufacturers to inhibit the onset
such as water, dirt, grease , or any debris that is
> and spread of corrosive attack .
capable of acting as an electrolyte. The presence There are many factors that affect the type,
of salt in any of the foregoing mediums tends to speed, cause , and the seriousness of metal
accelerate the current flow and hence speed the corrosion . Some of these corrosion factors can
rate of corrosive attack. be controlled ; others cannot. Preventive main
Once the electrical couple is made, the tenance factors such as inspection , cleaning, and
>
electron flow is established in the direction of painting and preservation are within the control
the negatively charged metal (cathode ), and the of the operating squadron . They offer the most
positively charged metal (anode) is eventually positive means of corrosion deterrence .
destroyed . All preventive measures taken with The electrochemical reaction which causes
respect to corrosion control are designed metal to corrode is a much more serious factor
285
ander wet , humid conditions. The salt in sea

>
MONEL RIVET
water and the salt in the air is the greatest single ( SMALL CATHODE )
cause of aircraft corrosion. Hot climates speed
he corrosion process because the electro
chemical reaction develops fastest in a warm
solution , and warm moisture in the air is usually
sufficient to start corrosion if the metals are
uncoated. As would be expected , hot dry
climates usually provide relief from constant
corrosion problems. Extremely cold climates
produce corrosion problems if a salt atmosphere
s present. Melting snow or ice provides the neces RELATIVELY LITTLE
sary water to begin the electrochemical reaction. CORROSIVE ATTACK
Thick structural sections are subject to cor ALUMINUM SHEET
osive attack because of possible variations in ( LARGE ANODE )
heir composition , particularly if they were heat
reated during fabrication . Similarly , when large
ections are machined or cut out after heat HEAVY
reatment, thinner sections have different CORROSIVE ALUMINUM RIVET
hysical characteristics than the thicker areas. In ATTACK ( SMALL ANODE )
nost cases , different in physical characteristics
provides enough difference in electrical potential
co render the piece highly susceptible to cor
-osion . Another corrosion factor regarding size
of materials lies in the area relationship between
lissimilar metals . When two dissimilar metals are
ased where possible contact may develop , if the o s
>
more active metal is small , compared to the less

ctive one , corrosive attack will be severe and
s
extensive if the insulation should fail. If the area
of the less active metal is small compared to the MONEL SHEET
other , anodic attack is relatively slight. Figure (LARGE CATHODE )
1-2 illustrates this factor.
One of the biggest problems in corrosion
control is in knowing what materials to use,
where to find them , and the limitations ap AM.50
plicable to their use . Materials used should be Figure 11-2. - Effects of area relationships in dissimilar
those covered and controlled by military metal contacts.
specifications, preferably those authorized
specifically for use on aircraft. Corrosion control 2. Preservation of Naval Aircraft, NavAir
nformation pertaining to materials, methods, 15-01-500 .
and techniques is scattered throughout many 3. Chart - Cleaning Materials for Naval Air
directives and instructions , and this information Systems -Maintenance and Overhaul Operations,
s constantly being revised as better chemicals NavAir 07-1-503 .
and protective methods are developed. The 4. Chart - Corrosion Preventive Compounds
following is a list of sources of information that used by Naval Air Systems Command , NavAir
should be readily available for reference in every 01-1 A-518.
unit's technical library or in the airframes shop. 5. Corrosion Control , Cleaning, Painting, and
1. Aircraft Cleaning and Corrosion Control Decontamination. (One volume of the Main
for Organizational and Intermediate Main tenance Instructions Manuals for all late model
tenance Levels, NavAir 01-1 A-509 . aircraft is on these subjects.)
286
6. Periodic Maintenance Requirements Cards should not be done unless corrosion is present.
(as applicable ). Touchup of new damage to paint finishes will
prevent corrosion from starting there .
The cleaning of aircraft is an important
PREVENTIVE MAINTENANCE function in retaining the aerodynamic efficiency
and safety of aircraft. In keeping with this
“ An ounce of prevention is worth a pound of importance , acceptable materials, methods , and
cure.” Where corrosion prevention on naval procedures for use in aircraft maintenance clean
aircraft is concerned the foregoing cliche is a ing are prescribed in current directives and must
ridiculous understatement. Compared with the be used . Instances of serious damage have
cost of some late model aircraft which runs into resulted to exterior and interior of aircraft due
millions of dollars the cost of corrosion pre to the lack of correct information regarding
vention is a mere pittance. Preventive main materials and equipment and their use . Ship
tenance is a powerful tool which can be used to board procedures are not necessarily the same as
effectively control even the most difficult cor procedures ashore , but the same materials are
rosion problems . available and comparable results are ac
Most corrosion prevention programs are complished, although different application
adjusted by the operating activity to meet severe methods may be necessary .
conditions aboard ship and then decreased in How often an aircraft should be cleaned
scope when the aircraft is returned to the depends on the type of aircraft and the environ
relatively mild conditions prevailing ashore. ment in which it has been operating . It is
When regular corrosion preventive maintenance important that the aircraft be kept in a clean
must be neglected in emergencies due to tactical condition and repeated cleaning should be ac
operating requirements, a period of intensive complished as often as necessary . The necessity
care should follow in order to bring the aircraft for cleaning is indicated whenever there is any
back up to standard. appreciable amount of soil accumulation within
Preventive measures most commonly taken exhaust track areas ; by the presence of salt
with respect to corrosion require the aircraft to deposits or other contaminants such as stack
be kept as clean as possible , all surface finishes gases; by evidence of paint surface deterioration
intact , correct and timely use of covers and such as softening, flaking, or peeling ; and by the
shrouds, periodic lubrication, and the applica presence of excessive oil or exhaust deposits or
tion of preservatives where required. Years of spilled electrolyte and deposits around battery
experience have proven the need for such areas. Cleaning is always mandatory immediately
measures if the aircraft are to remain airworthy. after exposure to fire extinguishing materials,
Where corrosion preventive maintenance is after exposure to adverse weather conditions
neglected , aircraft soon become unsafe to fly. and salt spray , after the aircraft has been parked
Squadrons with the best corrosion preventive near seawalls during high wind conditions, after
programs are likely to have the best safety low level flight, and after repairs or service
records, most utilization of aircraft, and lowest which has left stains , smudges , or other gross
operating costs. evidence of maintenance. A daily cleaning or
wipedown is required on all exposed unpainted
surfaces such as struts, actuating cylinder rods,
SURFACE MAINTENANCE etc.
Aircraft must be thoroughly cleaned before
Surface maintenance includes regular cleaning being placed in storage and should also receive a
of the aircraft as well as touchup of protective thorough cleaning at the time of depreservation.
paint coatings . Since paint touchup is ac Unpainted aircraft are cleaned and also polished
complished after removal of corrosion , coverage at frequent intervals. Aboard ship , cleaning and
on this subject is included under the heading, removal of salt deposits are necessary as soon as
Corrosion Elimination , later in this chapter . This possible to prevent corrosion .
does not imply that touchup of damaged paint Components which are critically loaded
287
designed with minimum safety margins to using them . ( The flashpoint is the temperature
conserve size and weight) such as helicopter at which the first flash from the material is seen,
otor parts, and components and parts which are as an open flame is passed back and forth over a
xposed to corrosive environments, such as sample of flammable liquid being heated in a
ngine exhaust gas, acid , or rocket blast, are cup . )
cleaned as often as possible to minimize Another hazard associated with solvents, and
exposure to these corrosive agents. to a certain extent with all cleaning materials, is
NOTE : Lubrication and preservation of the effect on the surface or material being
xposed components are necessary to displace cleaned . Some solvents will deteriorate rubber,
ny of the cleaning solution entrapped during synthetic rubber, asphaltic coverings, etc. This is
Che cleaning operation . such an important consideration that it must
always be taken into account when selecting
Materials cleaning materials. It may do a good job in
removing dirt , grease , oil, exhaust gas deposits,
Only NavAir specification cleaning materials etc. , but may also damage the object being
>
nay be used on aircraft. Navy specification cleaned or soften and ruin otherwise good paint
cleaning materials are made up and compounded coatings.
co accomplish definite results and are made Solvent , Drycleaning.This material is a
vailable only after complete testing and actual petroleum distillate commonly used in aircraft
Field acceptance . All specification materials are cleaning. It is furnished in two types, I and II .
nspected and tested before acceptance and Type I material, commonly known as Stoddard
lelivery to the supply activities. Cleaning agents solvent , has a flashpoint slightly above 100 ° F.
commonly used by Organizational and Inter Type II has a higher (safer ) flashpoint and is
mediate maintenance activities are included in intended for shipboard use .
Che following categories. In naval aviation maintenance , Stoddard
SOLVENTS. - Solvents are liquids which solvent (type I ) is used as a general all-purpose
Hissolve other substances. There are a great cleaner for metals , painted surfaces, and fabrics.
number of different solvents, but for cleaning It may be applied by spraying, brushing,
purposes , organic solvents are most often used . dipping, and wiping. This material is preferable
Some solvents are chlorinated . When solvents to kerosene for all cleaning purposes because
contain more than 24 percent by volume of kerosene leaves a light oily film on the surface.
chlorinated materials they must be kept in Mineral Spirits. This is another liquid
pecially marked containers and care must be petroleum distillate which is used as an all
aken to insure that equipment in which these purpose cleaner for metal and painted surfaces
solvents are used are designed and operated as to and as a diluting material for emulsion com
prevent the escape of such solvents , as a liquid
> pounds , but is not recommended for fabrics.
or vapor, into the workroom . Like Stoddard solvent , it may be applied by
All personnel occupied with or working near spraying , brushing, dipping, and wiping.
chlorinated solvents should be particularly care Aliphatic Naphtha.- This is an aliphatic
Ful to avoid breathing the vapors . While the hydrocarbon product used as an alternate
vapors from some solvents are more toxic than compound for cleaning acrylics and for general
others, prolonged breathing of the fumes can be cleaning purposes that require fast evaporation
njurious to health . and no remaining film residue . It may be applied
In addition to the breathing hazard associated by dipping and wiping. Saturated surfaces must
with solvents , they also present varying degrees not be rubbed vigorously , as it is a highly
of fire and explosion hazards, depending upon volatile and flammable solvent with a flashpoint
he material. It is considered that solvent below 80° F. Avoid prolonged breathing and
cleaners having a flashpoint greater than 105° F skin contact . Use in well - ventilated areas only.
are relatively safe. Those having flashpoints Aromatic Naphtha. - This is a petroleum
below 105 ° F require explosion proofing of aromatic distillate. This naphtha is a bare-metal
equipment and other special precautions when cleaner and is also used for cleaning primer coats
288
before applying lacquer. It will remove oil , control from a light mist or fogging spray to a
grease , and light soils. It is also highly flammable full spray with high -pressure water.
and reasonably toxic . Avoid prolonged breathing ALKALINE WATERBASE CLEANING
and skin contact . CAUTION : Do not use COMPOUND . - This compound is similar to the
aromatic naphtha on acrylic surfaces as it will water emulsion cleaner. It is a general purpose
cause crazing ( fine surface cracks). cleaner used to remove light to moderate soils. It
Safety Solvent . -Methyl chloroform is is mixed in 1 part compound to 9 parts water
intended for use where a high flashpoint and less for light soils and 1 part compound to 3 parts
toxic solvent than carbon tetrachloride is water for removing medium soils. It may be
required . It is used for general cleaning and applied to the surface by mopping, wiping , spray
grease removal of assembled and disassembled equipment , or foam producing equipment. It is
>
engine components in addition to spot cleaning, safe for use on fabrics, leather, glass, ceramics,
but should not be used on painted surfaces. and transparent plastics. Follow the previously
Safety Solvent is not suitable for oxygen sys described procedure for washing the aircraft and
tems although it may be used for other cleaning rinse thoroughly with fresh water before the
in ultrasonic cleaning devices. It may also be compound dries to prevent streaking.
applied by wiping, scrubbing, or booth spraying . SOLVENT EMULSION CLEANERS . - This
The term Safety Solvent is derived from the high cleaner, conforming to Specification P -C -444, is
flashpoint . Many later issue maintenance intended for heavy duty cleaning and should be
manuals label safety solvent as Trichlorethane used with caution around painted surfaces as it
1,1,1 . will soften paint if in contact with the paint
Methyl Ethyl Ketone (MEK ).– This material is finish very long. It will remove corrosion
used as a cleaner for bare -metal surfaces. It will preventive coatings and should not be used on
not mix to any great extent with water but is a parts thus protected unless it is desired that such
diluent for lacquers. It is applied with wiping protective coatings be removed . For heavy
cloths or soft bristle brushes over small areas at a cleaning , the cleaning compound is mixed in a
time. concentration of 1 part compound to 4 parts of
WATER EMULSION CLEANERS . - Emulsion dry -cleaning solvent ( Stoddard solvent) or
cleaners tend to disperse contaminants into tiny mineral spirits. For lighter duty use , it can be
droplets which are held in suspension in the mixed at a 1 to 9 ratio.
cleaner until they are flushed from the surface . WATERLESS CLEANER . – This compound is
-
Water emulsion compound conforming to intended for use on painted and unpainted
MIL - C-22543 contains emulsifying agents, aircraft surfaces in heavy duty cleaning opera
coupling agents , detergents, solvents, corrosion tions where water for rinsing is not readily
inhibitors, and water. It is intended for use on available or where freezing temperatures do not
painted and unpainted surfaces in heavy duty permit the use of water. It is relatively nontoxic,
cleaning operations where milder specification noncorrosive, nonflowing gel or cream , and its
materials of lower detergency would not be detergent properties enable it to be used as an
effective . It is used in varying concentrations, effective agent for the removal of grease , tar,
depending on the condition of the surface. A wax , carbon deposits , and exhaust stains. It
concentration of 1 part compound to 4 parts should not be applied to canopies or other
water, by volume, is recommended for heavier acrylic plastic surfaces. It is safe for use as a
soiled surfaces. For mildly soiled surfaces, the waterless hand cleaner.
concentration is changed to 1 part compound to MECHANICAL CLEANING MATERIALS.
9 parts water, by volume . Starting at the bottom
> Mechanical cleaning materials such as abrasive
of the area being cleaned, apply the mixed papers , polishing compounds, polishing cloths,
solution by spraying or brushing to avoid wools , wadding, etc. , are available in the supply
streaking. Loosen surface soils by a mild brush system for use as needed. However, their use
ing or mopping and follow with a thorough fresh must be in accordance with the cleaning proce
water rinse. The automatic shutoff type water dures outlined in NavAir 01-1 A-509 , the specific
spray nozzle is best for rinsing. It gives hand aircraft Maintenance Instructions Manual, and
289
directions supplied with the material being used factors, such as the amount of cleaning that is
f damage to finishes and surfaces is to be regularly performed, the type of aircraft that is
voided. In cases of conflicting information, being cleaned , the location of the activity , and
>
NavAir 01-1 A-509 will always take precedence. the availability of facilities such as air pressure,
Aluminum Oxide Paper. -Aluminum oxide water, and electricity.
paper ( 300 grit or finer) is available in several Several specialized items of equipment are
orms and is safe to use on most surfaces since it available for cleaning aircraft. These include
loes not contain sharp or needle -like abrasives pressure type tank sprayers, a variety of spray
which can embed themselves in the base metal guns and nozzles , high - pressure cleaning
peing cleaned or in the protective coating being machines, and industrial type vacuum cleaners.
maintained . The use of carborundum ( silicon One of the latest devices for faster and
carbide) papers as a substitute for aluminum economical cleaning of aircraft is a swivel type
oxide paper should be avoided . The grain struc conformable applicator cleaning kit developed
ure of carborundum is sharp , and the material is by the 3M Company . Officially designated
so hard that individual grains can penetrate and Scotch -Brite Conformable Applicator Cleaning
pury themselves even in steel surfaces. Kit No. 251 , it is designed to clean aircraft
Powdered Pumice . - This material is a mild exteriors several times faster than using cotton
brasive cleaner. The pumice is used as a slurry mops or bristle brushes.
with water and is applied to the surface with The applicator head of the cleaning kit is
clean rags and bristle brushes . curved and flexible to conform readily to
Impregnated Cotton Wadding . -Cotton which convex and concave aircraft exteriors. A swivel
has been impregnated with a cleaning material is joint on the back of the applicator head provides
ised for the removal of exhaust gas stains and further flexibility . The 5 x 7 inch Scotch Brite
For polishing corroded aluminum surfaces . It is cleaning and polishing pad attaches easily to the
also used on other metal surfaces to produce a applicator head and provides a more aggressive
high reflectance. and efficient scrubbing medium than bristle
Aluminum Metal Polish . - Aluminum metal fibers . It can be used without fear of scratching
polish is used to produce a high -luster, long aluminum or painted surfaces.
asting polish on unpainted aluminum -clad sur The swivel and applicator head are attached
aces. It is not used on anodized surfaces as it to a standard brush handle . The excellent
will remove the oxide coat . conformability of the applicator allows easier
Aluminum Wool . – Three grades of aluminum application of a constant scrubbing pressure on
vool - coarse , medium, and fine -are stocked for
> curved skin panels and eliminates the need for a
general abrasive cleaning of aluminum surfaces. maintenance stand to keep brushes in maximum
Lacquer Rubbing Compound, Type III. -For contact with the surface .
he removal of engine exhaust residues and Some larger shore activities maintain a self
minor oxidation, lacquer rubbing compound, contained vehicle Flight Line Maintenance
Type III , may be used. Heavy rubbing over rivet
> Master for use of all tenant activities. The Flight
heads or edges where protective coatings may be Line Maintenance Master is self-propelled and
hin should be avoided as the coverings may be self -contained . It provides a heated soap solution
lamaged most easily at these points . with its own water system . It has a 1,000 - gallon
capacity and is equipped with an extendable
Cleaning Equipment boom to accommodate cleaning of high
horizontal and vertical stabilizers.
The cleaning of aircraft not only requires the The cleaning solution is sprayed at high
use of correct cleaning materials , but also the pressure from the boom or ground level posi
use of properly maintained equipment to tions or both positions simultaneously . Control
produce efficient and satisfactory results. A of the boom and cleaning solution can be made
pecific cleaning area should be prepared and from the boom or the vehicle cab . The
equipped for performing cleaning operations . maneuverability of the vehicle makes it extreme
The choice of equipment depends on several ly efficient in cleaning all exterior aircraft
290
surfaces. Brushing of surfaces can be easily components that can be damaged by moisture or
accomplished by the boom operator. The the cleaning agent being used.
ground hose is equipped with a crank rewind WATER RINSE CLEANING . - The water
and is 50 feet long . The boom is equipped with rinse method is recommended as the most
floodlights to accomodate nighttime use of the efficient and satisfactory method of cleaning
vehicle. As with other support equipment , the aircraft when they are only lightly contaminated
maintenance master should only be operated by with loosely adhering soils and water soluble
qualified and licensed personnel. In some cases corrosion products . The aricraft is prepared as
specialized equipment must be manufactured previously outlined , and all materials and equip
locally by the activity , otherwise it is procured ment that will be required during the cleaning
through regular supply channels . are ascertained to be on hand and ready for use.
In addition to the specialized equipment The proper washing procedure to insure
mentioned above, other items such as hoses, complete coverage is illustrated and described in
brushes, sponges, and wiping clothes are figure 11-3 . Apply water by progressing upward
required for aircraft cleaning. These items are and outward , scrubbing briskly with a long
procured through supply . handled fiber cleaning brush as necessary while
Items of personal protection such as rubber the water is being applied. Do not scrub aa dried
gloves, rubber boots , goggles, and aprons should surface . After scrubbing, rinse the surface from
be worn when necessary to protect clothing, the top downward with a high -pressure stream
skin , and eyes from fumes and splashing of of water until all the water soluble residues and
caustic materials . loosened soils have been completely flushed off
the aircraft.
Cleaning Methods and Procedures WATER EMULSION CLEANING . - The
The first step in cleaning the aircraft is emulsion cleaning method is used to clean
selecting the proper cleaning agent for the aircraft contaminated with oil, grease , or other
method of cleaning to be used . The recom foreign matter which cannot be easily removed
mended type cleaning agent for each method , by other methods. The aircraft is prepared in the
including instructions and precautions to be same manner as it was for the water rinse
observed in their use , may be found in NavAir method .
01-1 A-509 and the applicable Maintenance Wet down the surface to be cleaned with fresh
Instructions Manual for the type of aircraft water. Apply a concentrated solution of 1 part
being cleaned . emulsion compound cleaner to 4 parts of water
The next step is the preparation of the to the heavily soiled areas, such as engine
aircraft for cleaning. Ground the aircraft to the nacelles, landing gear assemblies, or other special
deck after spotting it in a cool place if possible. areas that will require such a strong solution.
If the aircraft has been heated while parked in Scrub these areas and allow the concentrated
the sun or areas of the aircraft are heated as a solution to remain on the surface . Limit the size
result of operations , it should be cooled before of the area being cleaned to that size which can
the start of cleaning by the use of fresh water be easily cleaned while keeping the surface wet.
washdown . Many cleaning materials will clean Next apply a diluted solution of emulsion
faster at elevated temperatures, but the risk of compound and water, mixed to a ratio of 1 part
damage to paint , rubber, and plastic surfaces is emulsion compound to 9 parts water, to the
increased by the cleaners which are concentrated entire surface to be cleaned including those areas
by the rapid solvent evaporation caused by the covered with the concentrated
previously covered
high temperatures. Static electricity generated solution . Scrub the surfaces thoroughly and
by the cleaning operation will be dissipated allow the solution to remain on the surfaces 3-5
through the ground wire. After securing all the minutes before rinsing. Rinse from the top
obvious openings such as canopies and access downward until all soils have been removed . If a
panels, further secure the aircraft against entry high-pressure stream of water is used for rinsing,
of water and cleaning compounds as necessary. hold the nozzle at an angle and a reasonable
Mask or otherwise cover all equipment or distance from the surface being sprayed .
291
STEP 1 WASH THE UNDERSIDE OF WING ,

SPRAYING FROM THE CENTER
SECTION TOWARDS THE WING
TIPS .
5ਣ ಕಲ್ಲಿ
NOTE : OPEN DOORS AND FLAPS
TO FLAPWELLS , DIVE BRAKES ,
SPOILERS , CONTROLLABLE LEAD
ING EDGES , ETC. , TO PERMIT
CLEANING OF HIDDEN AREAS .
ܵ‫ܕܪ‬ laul
STEP 2 WASH THE UNDERSURFACE OF
FUSELAGE AND TAIL SECTIONS
FROM LANDING GEAR TOWARDS
BOTH ENDS AND SPRAY IN THE
DIRECTION OF MOVEMENT .
STEP 3 WASH THE UPPER SIDE OF WINGS

AND CENTER SECTION OF FUSELAGE .
DIRECT SPRAY INWARD WHILE MOVING
OUTWARD TOWARDS WING TIPS .
SPRAY THE REMAINING PARTS

STEP 4 OF THE UPPER SIDE OF FUSE
LAGE AND TAIL SECTIONS MOV
ING FROM CENTER TO ENDS . ALL
AREAS OF THE AIRCRAFT MUST BE
COMPLETELY COVERED BY THE
CLEANING SOLUTION .
LEGEND
DIRECTION OF STEPS
DIRECTION OF SPRAY
SPRAYED AREAS
AM, 51
Figure 11-3 . - Aircraft washing procedures.
292
If any areas are still not clean , repeat the approximately 10 minutes ; scrub and wipe off
operation in those areas only. After rinsing, the thoroughly with a clean wiping cloth . Make sure
aircraft may be dried with a clean sponge or all soils and cleaning material are removed ,
cloths to insure against streaking that could be exercising special care around fasteners and
caused by emulsion cleaning. Normally , if the unsealed areas. In freezing weather a dry ap
aircraft is thoroughly rinsed , streaking will be plicator should be used in lieu of a dampened
held to a minimum . one .
SOLVENT - EMULSION CLEANING.
Solvent -emulsion cleaning is intended for clean Post-Cleaning Requirements
ing heavily soiled unpainted surfaces and parts
and for use in removing corrosion preventive Following cleaning, the aircraft should be
coatings. The cleaning compound is mixed in a relubricated in accordance with the Maintenance
concentration of 1 part compound to 9 parts of Requirements Cards. Insure that all low-point
dry cleaning solvent or mineral spirits. The solu drains are open . Apply aircraft preservatives as
tion is applied to a water -free surface, otherwise required to those clean, exposed unpainted
the water would lessen the solvent action . Since surfaces. The types of preservatives are discussed
this cleaner will remove thick preservative mate later in this chapter. Insure that the felt wiper
rials, it should be used with care to prevent washers on all hydraulic cylinders are moistened
unwanted removal of such coatings. with hydraulic fluid and that all exposed strut
The solution is applied by brush or with a and actuating cylinder rods are wiped down with
high -pressure spray using a nozzle that gives a a clean rag saturated with hydraulic fluid .
coarse fan -shaped spray . Scrub the surface with Remove any damaged or loosened sealant and
a brush as the solution is being applied . Allow replace in accordance with the applicable Main
the solution to remain on the surface long tenance Instructions Manual or Structural
enough to loosen the soil without drying. Repair Manual .
Reapply and rescrub the more difficult soiled Figure 11-4 illustrates the documentation of a
areas as necessary . Rinse thoroughly , using a Support Action Form (SAF ) utilized to account
large volume of fresh water to remove all loose for the time spent cleaning an aircraft. The
soils and cleaning compound . spaces 1 through 9 and A and B are self
SPOT CLEANING . – Light oily soiled surfaces explanatory and should be filled in accordingly.
may be spot cleaned by wiping these areas with For detailed instructions on the SAF and its
a dry -cleaning solvent . The solvent is applied uses, consult Military Requirements for Petty
with a saturated wiping cloth . Brush or wipe the Officer 3 & 2 , NavPers 10056 -C , or OpNav
surface as necessary then wipe clean with a dry 4790.2 .
cloth, removing the solvent residue and loosened NOTE : If the cleaning is done after normal
soil. The solvent wipe may leave a light residue working hours, on Saturday, Sunday , or
which may be removed with soap and water declared holidays and the activity concerned is
followed by fresh water rinsing. required to record manhour data, a Manhour
WARNING : Drycleaning solvent should not Accounting (MHA ) Card must be submitted in
be used in oxygen areas or around oxygen addition to the SAF.
equipment . The solvent is not oxygen com
patible and will cause explosion and/or fire. USE OF COVERS AND SHROUDS
WATERLESS WIPE DOWN . - When water is
not available , heavy soils and operational films Each aircraft, when delivered by the manufac
may be removed by using waterless cleaner. The turer, is equipped with a complete set of tailored
cleaner is applied by dipping a dampened cloth dust and protective covers. A typical set of
into the creamlike waterless cleaning material covers is shown in figure 11-5 installed on an
and then spreading the material thinly over the A -6A .
area to be cleaned . Scrub the surface until the All covers and shrouds should be installed in
soil and cleaner become intermixed or emulsi such a manner that free drainage is assured. Do
fied. Allow the material to remain on the surface not create a bathtub which will trap and hold
293
1 2 3 4 5 6 7 B 9 A 8
NAINT ACTION TYPE ITEMS MAN

TYPE АСТ. WORK SUPPORT LOCAL
NOVEMBER
LEVEL SIGNATURE
MMMPC
REVISED
EQUIP. ORG . CENTER DATE CODE MAINL PROC . HOURS CONTROL

FORM
*
TEST
1964
NO
.10
A.P.BBALA1.2.1100.250,2.0 A ,/ 1,412 FE. Bruia
FORM
SUPPORT CODES TYPE MAINTENANCE CODES
010 OPERATIONAL SUPPORT 'A GENERAL SUPPORT

020 CLEANING / PRESERVATION / DEPRESERVATION C PREFLIGHT INSPECTION
030 INSPECTION D POSTFLIGHT / DAILY INSPECTION
040 CORROSION CONTROL E ACCEPTANCE / TRANSFER INSPECTION
050 GENERAL FUNCTIONS F TRANSIENT MAINTENANCE
060 BUILD UP AND TEAR DOWN / ENGINE L LOCAL MANUFACTURE
TEST STAND OPERATION T SUPPLY SUPPORT
070 MISSION SHOP SUPPORT U RECLAMATION AND SALVAGE
080 INSPECTION OF AVIATORS EQUIPMENT ,
SAFETY AND SURVIVAL EQUIPMENT
090 NON - AERONAUTICAL WORK
IRMO57379
AM.6
Figure 11-4. -SAF documentation for cleaning aircraft.
AM.52
Figure 11-5 . - A -6A dust and protective covers,
294
water. Shrouds or covers may also act as a the sand or gravel from shoe soles before climb
greenhouse in warm weather and cause col ing on aircraft.
lection and condensation of moisture under When removing cowling and access plates dur
neath . They should be loosened or removed and ing inspections the removed hardware should
the aircraft ventilated on warm sunny days. not be placed on the deck to blow around and
Where protection from salt spray is required become scratched . If it is not practical to pro
aboard carriers, the covers should be left in place vide pads or cushioning for these components,
and the aircraft ventilated only in good weather. they should at least be secured to prevent their
Fresh water condensate will do far less damage movement . When using handtools to remove
than entrapped salt spray . screws and quick-opening fasteners on the air
In emergencies where a regular waterproof craft exterior , particular care should be taken to
canvas covers are not available, suitable covering avoid scratching the paint . Five minutes of extra
and shrouding may be accomplished by using time spent in careful use of tools could save
polyethylene sheet , polyethylene coated cloth, hours of paint touchup and corrosion removal
or metal foil barrier material, all of which are work later .
available in the Navy supply system . These
covers should be held in place with adhesive AIRCRAFT PRESERVATION
tapes designed specifically for severe outdoor
application . The tapes are also available in The susceptibility of an aircraft to corrosion
supply . damage is greatest during those periods when the
aircraft is dirty , inactive , or being shipped . Since
GROUND HANDLING REQUIREMENTS aircraft spend more time on the ground than in
the air , even in an active squadron , the need for
Maintenance Instructions Manuals for aircraft effective protection becomes apparent .
usually provide brief and simple ground handling Suitable protection against corrosive attack is
procedures which , if observed , can do much achieved essentially by placing a barrier between
toward reducing corrosive attack . Little things the cleaned surface that is to be protected and
like heading the aircraft into the wind and any possible source of moisture . During manu
installing available covers, battens, shrouds, etc. , facture or overhaul of the aircraft, protective
to keep water, salt,> and dirt out of areas difficult barriers such as electroplate , paint , or chemical
to get at and easy to overlook , can save a surface treatment are provided. Surfaces that
tremendous amount of maintenance work later. cannot be so treated, and in some instances the
There are many other common sense practices treated surfaces themselves, must be covered
which should be observed to minimize paint with special corrosion-preventive compounds.
damage and the loss of built -in protective The protection these compounds give is effective
systems during normal ground handling of the only if no moisture , dirt , or active corrosion is
aircraft. Much damage is done to aircraft paint present on the treated surface. It is essential ,
films by failure to use the tiedown points therefore, that the aircraft be thoroughly clean
provided , or by passing tiedown cables and lines and dry before a preservative compound is
over or around supporting structures in such a applied . It is also necessary that an unbroken
manner that the paint finish is worn , chipped , or film of preservatives be applied in as moisture
broken, especially at sharp edges. free an atmosphere as practicable .
Painted aircraft surfaces will withstand a nor Compounds alone do not provide complete
mal amount of foot traffic and abrasion by fuel protection . Tapes, barrier paper, and sealing de
hoses and air lines . However , shoe soles and fuel vices must also be used to seal off the numerous
ing hoses pick up bits of sand , gravel, and metal openings on aircraft which , if allowed to remain
chips and become a coarse abrasive which op during long-time storage , would permit the
scratches and scuffs the protective finish to the entry of moisture and dirt . To provide addi
point where it is rendered completely ineffective tional protection against corrosion a complete
under shipboard operating conditions. For this moisture barrier is sometimes provided . Internal
reason , time should be taken to wipe or brush areas that have been sealed off are dehydrated
295
y installing dessicants (moisture absorbents) to salt spray is required . Present instructions gen
emove entrapped unless the cavity is protected erally limit its use to seaplanes and amphibian
with a vapor corrosion inhibitor. When any area surfaces.
annot be sealed adequately , provision must be Grade 2 is a soft-film , grease -type material
nade for ventilation and moisture drainage. that can be used on most operating parts. Its
When certain installed equipment in an air chief disadvantage is the fact that it may be
raft is not being used regularly , its components washed off under direct exposure to salt water
re required to be preserved . For example , the or may be removed by inadvertent wiping. It
uns of an aircraft must be cleaned after each protects under relatively severe conditions and,
iring. The type of oil or other protective treat given adequate maintenance and touchup as
nent which is to be applied subsequently de necessary , can be used for most maximum pro
ends upon the anticipated period of idleness tection requirements.
or the guns. Grade 4 preservative forms thin , semitrans
The requirements for the preservation of parent films through which identification data
perating aircraft are of the most concern of a can usually be read . It also sets up relatively dry
Third or Second Class AMS; therefore , this sec to the touch so that preserved parts may be
ion emphasizes the use of preservative coatings easily handled. This grade has proved particu
o supplement paint films, prevent salt spray and larly effective in protecting wheel well areas and
alt water damage to operating aircraft, and other exposed surfaces where film transparency
minimize exposure during routine maintenance is required and moderate protective characteris
nd repair . tics can be tolerated . The main disadvantages of
In maintenance of aircraft surfaces, under this material is that it is easily removed by water
perating conditions, preservation means supple spray and requires replacement at 1 -month inter
nenting the protection already present, or pro vals under severe exposure conditions.
iding temporary protection to damaged areas,
y the use of various protective coatings and Sprayable, Strippable
arrier materials . A brief description of some of Coating Compounds
he more common materials used in aircraft pres
rvation and readily available in Navy stock is Activities based outside of the continental
ncluded in the following paragraphs . United States occasionally receive aircraft from
rework activities or the procuring agency via
Compound , Corrosion -Preventive, ocean surface shipment. This is especially true of
Solvent Cutback helicopter and limited range fighter aircraft.
These aircraft are protected during shipment
This material is familiarly known as " paral with a sprayable , strippable coating system , con
etone . " It is supplied in three grades for spe forming to MIL -C -6799 , Type II . Type II coat
ific application . All grades of this compound ing systems , which are more common to mainte
nay be applied by brush , dip , or spray . They nance personnel, are normally applied by
may be easily removed with Stoddard Solvent or spraying and have no harmful effects on metal ,
nineral spirits . These materials are designed for plastic , or painted surfaces. It is also useful for
old application . Some preservative compounds protecting transparent acrylic surfaces, such as
nust be applied hot ; therefore, when intending canopies , against abrasion during maintenance or
o use one of the grades of this solvent cutback extended periods of down time . The type II
naterial, the specification number (MIL - C system consists of a black base coat and aa white
6173 ) should always be verified . topcoat to provide maximum heat reflection
Grade 1 forms a dark , hard -film , opaque during outside exposure . Nylon ripcords with
over . Its general use is limited because of the finger size loops are placed strategically about
ifficulty in removing aged coatings and also be the aircraft prior to spraying to accommodate
ause of the hiding power of the material when the manual stripping of coatings. When properly
t is applied over corroded areas. This material is applied , the coatings can be easily removed. If
used only where maximum protection against coatings are sprayed too thin for easy removal,
296
they can be recoated and allowed to dry. The will show 100 -percent protection for a period of
top layer will adhere to previous layers and all 30 days or more .
layers may be manually stripped in one opera Lubrication Oil , General
tion .
Purpose, Preservative
Corrosion -Preventive Petroleum
There are several different types of lubricating
(MIL - C - 11796 ) oil, some of which contain preservatives. In
order to be absolutely sure that the proper oil is
These preservatives are designed for hot appli used in a given situation , each must be identified
cation and are available in two classes-Class 1
( hard film ) and Class 3 (soft film ). Both consist with its specification number. The specification
number for the oil discussed in this section is
of corrosion inhibitors in petroleum . They are VV -L- 800 .
removed with Stoddard Solvent or mineral
VV-L-800 oil was compounded for lubrica
spirits. Where a hard film is not necessary, Class
3 should always be used as it is easier to apply
tion and protection of piano -wire hinges and
other critical surfaces and whenever a water
and remove yet renders the same degree of pro displacing, low -temperature, lubricating oil is re
tection . Class 1 is generally used for long-time quired .
indoor protection of highly finished metal sur VV-L-800 may be applied , as received , by
faces and aircraft control cables. Class 3 is used
brush , spray , or dip methods. It is readily re
to provide protection of metal surfaces such as
moved with Stoddard solvent or mineral spirits.
antifriction bearings, shock -strut pistons , and
other bright metal surfaces. Lubricating Oil, General
Class 1 must be heated to 170° to 200° F
Purpose, Low Temperature
before applying by brush or dip . For brushing
class 3 material, it must be between 60° and
This general purpose oil (Specification MIL - L
120° F and for dipping , between 150° and 180°
F. 7870) is suitable for use anywhere that a general
purpose lubricating oil with low temperature,
low viscosity , and corrosive -preventive prop
Oil, Preservative , erties is required .
Hydraulic Equipment This oil is suitable for brush , spray , dip , or
general squirt-can application . It is not necessary
This oil is used in the preservation of hydrau to remove before reoiling or for inspection .
lic systems and components and shock struts.
This oil is similar in appearance to , but is not Corrosion Preventive
interchangeable with , operating hydraulic fluid, Compound (MIL - C -81309 )
therefore before using operating hydraulic fluid
(MIL - H -5606 ) or this preservative oil (MIL This material is a water displacing corrosion
H-6083 ) for any purpose the specification num prevention compound and lubricant. It forms a
ber should be checked to ascertain that the cor thin , clear protective coating when applied by
rect oil is being used . The preservative oil aerosol , brush , dip , or spray . It offers only short
contains oxidation and rust inhibitors, viscosity term protection so must be reapplied frequently.
improver, and antiwear agents . Hydraulic parts On exposed surfaces, protection at its best
and components being turned in for screening would be 7 days between applications and up to
and repair are flushed and drip drained with 30 days on internal surfaces which are protected
MIL - H -6083 oil prior to being forwarded . from direct outside environments . It is easily re
Designed primarily for hydraulic components moved with drycleaning solvents. It is very effec
this oil may be used on any bare critical surface tive when used in the following areas : Piano-wire
that needs protection . Operating hydraulic fluid hinges, removable fasteners, B -nuts, linkages,
will protect a steel panel immersed in water for bolts and nuts ,, ejection seat mechanisms,
only about 48 hours. The same metal panel canopy locks, control surface hinges, electrical
coated with MIL - H -6083 inhibited hydraulic oil connectors , and microswitches.
297 .
Packaging and Barrier Materials CORROSION DETECTION
A minimum of packaging is necessary at the Timely detection of corrosion is essential to

operating activity level . However , critical aircraft any corrosion control program . Of course corro
nd engine areas require shrouding against con sion can be detected after a part fails (if the
amination during maintenance and repair. Fuse aircraft can be recovered ) , but it is too late to do
age openings require adequate seals when clean anything about it other than to intensify inspec
ng and stripping materials are used . At least tions of other, similar aircraft . Inspection for
hree acceptable barrier materials are available in corrosion and deterioration should be a part of
Navy stock for sealing and shrouding large air all routine inspections . There are , on every air
craft openings . craft, certain areas that are more prone to corro
WATER -VAPORPROOF BARRIER MATE sion than others . One should check these areas
RIAL.- This material is a laminated metal foil carefully . In order for the corrosion inspection
arrier that has good water-vapor resistance and to be thorough the person inspecting must know
an be used for closing of intake openings, for the types of corrosion likely to be found and the
rotection of acrylics during cleaning , and for symptoms or appearance of each type . Some
ecessary packaging of removed components times corrosion is hidden and special detection
nd accessories being returned to overhaul . It is methods are utilized in the search. Various as
neat sealable with a soldering or clothes iron . pects of corrosion detection are discussed in the
POLYETHYLENE PLASTIC FILM . - This following sections .
barrier material is used for the same purposes as
he metal foil barrier material and is much less
LOCATION OF CORROSION
xpensive. It is however not puncture resistant. PRONE AREAS
The plastic film is heat sealable only with special
Equipment .
POLYETHYLENE COATING CLOTH . - This Discussion of corrosion prone areas in this
cloth is used to a great extent in ground support section includes trouble spots or areas that are
equipment covers . Its use is preferred over the common to all aircraft. For this reason , coverage
lastic film material for general aircraft shroud for any given aircraft model is not necessarily
ng because of its greater tear and puncture re complete . Figure 11-6 illustrates trouble spots
istance . applicable to a jet engine aircraft. Reference to
TAPE , FEDERAL SPECIFICATION the Periodic Maintenance Requirements Cards
PP - T -60, CLASS 1. - This pressure -sensitive for specific model aircraft will enable inspec
ape is used for closure of small aircraft openings tions to be amplified and expanded to the neces
nd for direct contact use on noncritical metallic sary degree .
urfaces. The tape has moderate water -vapor re
istance, which is generally adequate for mainte
ance use . The main disadvantage of this tape is Exhaust Trail Areas
hat some cloth-backed materials have not been
preshrunk , and tape closures tend to pull loose
vhen exposed to high humidity conditions . Both jet and reciprocating engine exhaust de
posits are very corrosive. These deposits are par
PRESSURE SENSITIVE ADHESIVE ticularly troublesome where gaps, seams, hinges,
TAPE.- This item is a material developed speci and fairings are located down the exhaust path
ically for exterior preservation and sealing used and where the deposits may be trapped and not
n aircraft maintenance programs. It is designed reached by normal cleaning methods. Inspection
For application at temperatures as low as 0° F of these surfaces should include special attention
ind should perform satisfactorily over the tem to the areas indicated in figure 11-7 . Inspection
.
perature range from -65° F to 140° F. It is an procedures should also include the removal of
excellent general purpose tape for exterior pre fairings and access panels located in the exhaust
ervation and sealing operations . path.
298
3 -10 9
2 11
5
13
16
17 -14 12
19 18
20
22
21
23
24
AM.53
1. Pallet components. 13. Exposed indicator switches.
2. Rudder pedals. 14. Magnesium wheels.
3. Cockpit floor. 15. Exposed rigid tubing.
4. Battery compartment. 16. Main wheel well.
5. Piano hinges. 17. Cooling air inlet.
6. Control cables. 18. Bilge areas.
7. Cooling air inlet 19. Piano hinges.
8 Missile rocket blast areas. 20. Relief tube exits.
9. Exhaust areas Exposed position indicator switches.
21 .
10 . Extensible equipment platform compartments. Air intake ducts and engine frontal areas.
22
11 . Flap carriage cutouts. 23. Exposed rigid tubing .
12. Slat drives and track cutouts. 24. Magnesium wheels.
Figure 11-6. -Typical corrosion prone areas on jet engine aircraft.
JATO , Rocket, and Gun Blast Areas Battery Compartments and

Battery Vent Openings
Surfaces located in the path of JATO, rocket,
and gun blasts are particularly subject to corro Fumes from battery electrolyte are difficult
sive attack and deterioration (fig. 11-8 ). In addi to contain and will spread throughout the bat
tion to the corrosive effect of the gases and ex tery compartment, vents, and even adjacent in
haust deposits , protective finishes are often ternal cavities, causing rapid , corrosive attack on
blistered by heat , blasted away by high -velocity unprotected surfaces. The external skin area
gases, or abraded by spent shell casings or solid around the vent openings should also be checked
particles from gun and rocket exhausts. These regularly for this type corrosion . Corrosion from
areas should be watched for corrosion and this cause will continue to be a serious problem
cleaned carefully after firing operations . whenever batteries are used .
299
they may attract and hold moisture, which in
UUUUU
turn causes corrosive attack . Inspectors should
pay attention to bilge areas located under galleys
C and lavatories, and to personnel relief and waste
со
с
C C
C
disposal vents or openings on the aircraft ex
6 e C G C C teriors. Human waste products are very corrosive
C C C to the common aircraft metals.
0 с C C с с с с со
CC
СС
Bilge Areas
CC
CC
A common trouble spot on all aircraft is the
СС
bilge area. This is a natural collection point for
CCCCCCCC с waste hydraulic fluids, water , dirt, loose fas
>
teners , drill shavings, and other odds and ends of

debris. Oil puddles quite often mask small quan
tities of water which settle to the bottom and
CAROUND RIVET HEADS
UNDER FAIRINGS
E IN SKIN CREVICES set up hidden corrosion cells. Keeping bilge areas
free of all extraneous material, including oil, is
the best insurance against corrosion .
Wheel Wells and Landing Gear
The wheel well area probably receives more
punishement than any other area on the aircraft.
AM.54
Figure 11-7 . - Exhaust trail corrosion points.
It is exposed to mud, water, salt , gravel, and
other flying debris from runways during flight
operations and is open to salt water and salt
spray when the aircraft is parked aboard ship.
CORROSION PROBLEM AREAS Due to the many complicated shapes, as
semblies, and fittings in the area, complete
coverage with a protective paint film is difficult
to attain. Because of the heat generated from
braking, preservative coatings cannot be used on
jet aircraft landing gear wheels. During inspec
tions , particular attention should be given the
following:
Mangnesium wheels, especially around bolt
heads, lugs, and wheel web areas.
HESE AREAS ARE ALSO POTENTIAL
ATER TRAPS ON SOME AIRCRAFT Exposed metal tubing, especially at nuts and
ferrules, and under clamps and identification
GAS OUTLET DOOR tapes.
Exposed position -indicator switches and other
electrical equipment .
AM.55
Crevices between stiffeners, ribs, and lower
Figure 11-8. -Gun blast area corrosion points. skin surfaces which are typical water and debris
Lavatories and Galleys traps.
These areas , particularly on the deck behind Water Entrapment Areas
avatories, sinks, and ranges, where spilled food
nd waste products may accumulate , are likely Design specifications require that aircraft have
rouble spots if not kept clean . Even if some drains installed in all areas where water may col
contaminants are not corrosive in themselves, lect . However, in many cases these drains may
300
not be effective, either due to improper location CORROSIVE AGENTS ENTER

or because they are plugged by sealants, ex AT UNSEALED SKIN EDGES
traneous fasteners, dirt , grease, and debris. Daily
>
SPOT WELD SPOT WELD
inspection of drains should be a standard re
quirement , especially aboard ship.
Wing Fold, Flap and

Speed Brake Recesses
CORROSIVE AGENTS TRAVEL
Flap and speed brake recesses are potential BETWEEN SKINS, AROUND
RIVETS AND WELDS
corrosion problem areas mainly because they are
normally closed when on the ground. Dirt and CORROSION BUILD- UP CAUSES
water may collect and go unnoticed . Wing fold BUCKLING OF OUTER SKIN
areas present a different problem and , like wheel
wells, contain many complicated shapes and as
semblies which are difficult to cover with a pro
tective paint coating or preservative film . Wing
fold areas are extremely vulnerable to salt spray AM.56
when wings are folded aboard ship. Thorough Figure 11-9 . - Spot-welded skin corrosion points.
inspection of this area should include a mirror
check of the back sides of tubing and fittings. magnesium skin surfaces, with special attention
Also , particular attention should be paid to to edges, areas around fasteners, and cracked,
aluminum alloy wing lock fittings such as are chipped , or missing paint.
used on some current aircraft models. Corrosion of spot-welded skins is chiefly the
result of the entrance and entrapment of corro
External Skin Areas sive agents between the layers of metal . (See fig.
Most external aircraft surfaces are ordinarily 11-9 . ) Some of the corrosion may be caused
covered with protective paint coatings and are originally by fabrication processes , but its
readily visible or available for inspection and
progress to the point of skin bulging and spot
weld fracture is the direct result of moisture or
maintenance. Even here, certain types of con
figuration or combinations of materials become salt water working its way in through open gaps
and seams. This type of corrosion is first evi
troublesome under shipboard operating condi denced by corrosion products appearing at the
tions and require special attention if serious crevices through which the corrosive agents
corrosion difficulties are to be avoided.
entered . Corrosion may appear at other external
Magnesium skin , when painted over, is not or internal faying ( closely joined) surfaces, but is
visibly different from any other painted metal
usually more prevalent on external areas. More
surface. However , those surfaces which are of advanced corrosive attack causes skin buckling
magnesium are identified in the applicable Struc and eventual spot -weld fracture . Skin buckling
tural Repair Manual . When aircraft contain mag in its early stages may be detected by sighting
nesium skin panels, these must be given special along spot -welded seams or by using a straight
attention during inspections for corrosion . Some edge.
current aircraft have steel fasteners installed
through magnesium skin with only protective
finishes under the fastener heads or tapes over Piano Type Hinges
the surface for insulation . In addition , all paint Figure 11-10 illustrates the effect of corrosion
coatings are thin at trimmed edges and corners. on the piano wire type hinges used on most air
These conditions, coupled with magnesium's craft. These are not only prime spots for corro
sensitivity to salt water attack, make up a po- sion due to the dissimilar metal contact between
tential corrosion problem whenever magnesium the steel pin and aluminum hinge tangs, but are
is used . Therefore, any inspection for corrosion also natural traps for dirt, salt, and moisture.
should include the location and inspection of all When this type of hinge is used on access doors
301
IL
familiar reddish colored iron rust. When iron and
BARE STEEL HINGE PIN
its alloys corrode, dark iron oxide coatings
usually form first, and these coatings, such as
-AL. ALLOY EXTRUSIONS heat scale on steel sheet stock, may protect iron
surfaces rather efficiently. However, if sufficient
>
oxygen and moisture are present, the iron oxide

is soon converted to hydrated ferric oxide,
which is the conventional red rust .
F Aluminum
Aluminum and its alloys exhibit a wide range

of corrosive attack , varying from general etching
of the surfaces to penetrating attacks along the
HIDDEN CORROSION OCCURS internal grain boundaries of the metal . The
HERE . JOINT FREEZES AND corrosion products are seen as white to gray
LUGS BREAK OFF WHEN powdery deposits and more voluminous than the
HINGE IS ACTUATED original metal . In its early stages , aluminum
corrosion is evident as general etching, pitting ,
and roughness of the surface . The surface attack
progresses quite slowly at first; however , it will
be accelerated if corroding material is not given
AM.57 immediate attention .
Figure 11-10 . - Hinge corrosion points. Paint coatings tend to mask evidence of corro
sion , but the fact that the corrosion products are
and plates which are opened only during more voluminous will result in corrosion show
periodic inspections, they tend to freeze in place ing up as blisters, flakes, chips, lumps, or other
between inspections . The inspection for corro irregularities in the paint coating. Often white or
sion of these hinges should include lubrication gray streaks of corrosion products will become
and actuation through several cycles to insure readily apparent at breaks in the paint film . Any
complete penetration of the lubricant. such indications should result in further investi
gation to determine the extent that corrosion
APPEARANCE OF CORRODED PARTS has progressed .
One of the problems involved in corrosion Magnesium and Its Alloys

control is recognizing corrosion products when
they occur . The following paragraphs include Magnesium corrosion products are white and
brief descriptions of typical corrosion product quite large compared to the size of the base
characteristics of the more common materials of metal being corroded . The deposits have a
aircraft construction. Photographs of typical tendency to raise slightly and the corrosion
corroded surfaces are provided in NavAir 01 spreads rapidly . When white puffy areas are dis
1 A - 509 and reference to that publication will covered on magnesium it requires prompt atten
enable maintenance personnel to become more tion as the corrosion may penetrate entirely
familiar with and be able to identify corrosion in through the structure in a very short time .
its various stages.
Iron and Steel Copper and Copper Alloys

Possibly the best known and easiest recog Copper and its alloys are generally corrosion
nized of all forms of metals corrosion is the resistant , although the products of corrosive
302
attack on copper are commonly known . Some tect by forming an actual physical noncorrosive
times copper or copper alloy surfaces will barrier over the steel . Electroplated coatings,
tranish to a dull gray - green color and the surface particularly chromium on steel, are somewhat
may still be relatively smooth . This discoloration porous, and corrosion eventually starts at these
is the result of the formation of a fine-grained, pores or pin holes unless a supplementary coat
airtight copper oxide crust, called a patina. This ing is applied and maintained .
patina in itself offers good protection for the
underlying metal in ordinary situations. How Titanium
ever, exposure of copper and copper alloys to
moisture or salt spray will cause the formation Titanium is becoming more commonly used
of blue or green salts indicating active corrosion . in aircraft construction. It is a highly corrosion
These salts will form over the patina since this resistant metal , but it may show some surface
crust is not impervious to water (not moisture deterioration from the presence of salt deposits
proof). Copper alloys used in aircraft generally and other impurities, particularly at higher tem
have a cadmium-plated finish to prevent surface peratures. Corrosion products appear as minute
staining and deterioration . surface cracks. When used with other metals , in
sulation must be used to prevent dissimilar metal
Cadmium and Zinc
attack on the other metals .
FORMS OF CORROSION
Cadmium , particularly, is used as a coating to
prc .ect the part to which it is applied and to
provide a compatible surface when the part is in Corrosion may occur in several forms, de
pending upon the metal involved, its size and
contact with other materials. The cadmium plate
supplies sacrificial protection to the underlying shape , its specific function, atmospheric condi
metal because of its greater activity. That is, dur
tions, and the corrosion-producing agents pres
ent . Those described in this section are the
ing the time it is protecting the base metal, the
cadmium is intentionally being consumed . It more common forms found on aircraft struc
functions in the same way that an active magne tures. Corrosion has been cataloged and typed in
sium rod inserted in the water system protects many ways. For descriptive purposes, the types
are discussed here under what is considered the
the piping of a hot water heater. The cadmium
becomes anodic and is attacked first , leaving the most commonly accepted titles .
base metal free of corrosion . Zinc coatings are Direct Surface Attack
used for the same purpose , but to a lesser extent
in aircraft . Attack is evident by white to brown
to black mottling of the cadmium surfaces. The surface effect produced by the direct
These indications DO NOT indicate deteriora reaction of the metal surface with oxygen in the
tion of the base metal . Until the characteristic air is a uniform etching of the metal . The rusting
colors peculiar to corrosion of the base metal of iron and steel , the tarnishing of silver, and the
appear, the cadmium is still performing its pro general dulling of aluminum surfaces are com
tective function . Wire brushing or removal of the mon examples of surface attack. On aluminum
surfaces if such surface attack is allowed to con
mottled areas of cadmium merely reduces the
amount of cadmium remaining to protect the tinue unabated, the surface will become rough
and eventually frosted in appearance .
underlying structure .
Pitting Corrosion
Nickel and Chromium Alloys
The most common effect of corrosion on
These metals are also used as protective aluminum and magnesium alloys is called pit
agents, both in the form of electroplated coat ting. It is due primarily to the variation in struc
ings and as alloying constitutents with iron in ture or quality between areas on the metal sur
stainless steels . Nickel and chromium plate pro face in contact with a corrosive environment.
303
tting corrosion is first noticeable as a white or possibility of water accumulation, by avoiding

ay powdery deposit , similar to dust, which the creation of crevices during repair work , and
otches the surface. When the superficial de by elimination of any existing voids which may
osit is cleaned away , tiny pits or holes can be become water traps by the use of approved
en in the surface. They may appear as rela sealants and caulking compounds.
vely shallow indentations or deep cavities of
nall diameter. Pitting may occur in any metal ,
ut it is particularly characteristic of aluminum Intergranular Attack
nd magnesium . Including Exfoliation
revice Attack or All metals consist of many tiny building
oncentration Cell blocks called crystals. These crystals are some
times called grains. The boundaries between
Concentration cell corrosion is actually a these crystals are commonly referred to as grain
orm of pitting corrosion which is caused by the boundaries. Intergranular corrosion is an attack
ifference in concentration of the electrolyte or on the grain boundaries of some alloys under
he active metal at the anode and cathode. specific conditions. During heat treatment, these
Then there is concentration differences at two alloys are heated to a temperature which dis
ifferent points in an entrapped pool of water or solves the alloying elements. As the metal cools,
leaning solution , anodic and cathodic areas may
> these elements combine to form compounds ;
esult , and the anodic area will be attacked . and if the cooling rate is slow , they form dis
igure 11-11 illustrates the theory of concentra crimininantly at the grain boundaries. These
on cell corrosion . This type of attack is gen compounds differ electrochemically from the
rally detected where there are crevices , scale, material adjacent to the grain boundaries and
urface deposits, and/ or stagnant water traps. can be either anodic or cathodic to the adjoining
his type corrosion is controlled and prevented areas, depending on their composition . The pres
y keeping areas cleaned , by eliminating the ence of an electrolyte will result in attack of the
anodic area . This attack will generally be quite
rapid and can exist without visible evidence.
LOW METAL ION CONCENTRATION As intergranular corrosion progresses to the
more advanced stages, it reveals itself by lifting
up the surface grain of the metal by the force of
expanding corrosion products occurring at the
grain boundaries just below the surface . This ad
vanced attack is referred to as EXFOLIATION,
HIGH METAL ION CONCENTRATION
and its recognition by corrosion personnel and
immediate action to correct such serious corro
METAL ION CONCENTRATION CELL RIVETED LAP JOINT

sion is vital to aircraft safety. The insidious na
ture of such an attack can seriously weaken
HIGH OXYGEN CONCENTRATION structural members before the volume of corro
sion products accumulate on the surface and the
damage becomes apparent.
Metal that has been properly heat-treated is
not readily susceptible to intergranular attack ;
LOW OXYGEN CONCENTRATION
however, susceptibility can develop from local
ized overheating, such as could occur from weld
ing, fire damage, etc. If the intergranular attack
OXYGEN CONCENTRATION CELL
has not penetrated too far and sufficient struc
AM . 1128 tural strength remains, corrective procedures as
Figure 11-11 . - Concentration cell corrosion. outlined in the applicable Structural Repair
304
Manual could restore the aircraft to a flight unequal cooling from high temperatures during
status. heat treatment, and by internal structural re
Whenever intergranular corrosion is evident or arrangement involving volume changes. Stresses
suspected, it should be immediately brought to set up when a piece is deformed , those induced
the attention of senior personnel who can initi by press and shrink fits, and those in rivets and
ate appropriate action. bolts are examples of internal stresses. Con
cealed stress is more important than design
Dissimilar Metal Corrosion stress, especially because stress corrosion is diffi
cult to recognize before it has overcome the de
Galvanic or dissimilar metal corrosion is the sign safety factor. The magnitude of the stress
term applied to the accelerated corrosion of varies from point to point within the metal .
metal caused by dissimilar metal being in con Stresses in the neighborhood of the yield
tact in a corrosive medium such as salt spray or strength are generally necessary to promote
water. stress corrosion cracking, but failures have oc
Dissimilar metal corrosion is usually a result curred at lower stresses .
of faulty design or improper maintenance prac
tices which result in dissimilar metals coming in Fatigue Corrosion
contact . It is usually recognizable by the pres
ence of a buildup of corrosion at the joint Fatigue corrosion is a special kind of stress
between the metals. For example , aluminum and corrosion and is caused by the combined effects
magnesium materials riveted togehter in an air of corrosion and stresses applied in cycles to a
craft wing form a galvanic couple if moisture or part. NOTE : An example of cyclic stress is
contamination is present. When aluminum pieces the alternating loads to which the reciprocating
are attached with steel bolts or screws, galvanic rod on the piston of a hydraulic , double -acting
corrosion can occur around the fasteners. actuating cylinder is subject. During the exten
Aircraft manufacturer's utilize a variety of sion stroke a compression load is applied and
separating materials such as plastic tape , sealant, during the retracting or pulling stroke, a tensile
primer, washers, lubricants, etc. , to keep these or stretching load is applied . Damage from
metals from coming in direct contact and thus fatigue corrosion is greater than the combined
keep corrosion to a minimum . It is imperative damage of corrosion and cyclic stresses if the
that these separating materials remain intact or part was exposed to each separately . Fracture of
are replaced , restored, or repaired as necessary a metal part due to fatigue corrosion generally
throughout the life of the aircraft. occurs at a stress far below the fatigue limit in a
Since some metals are more active than laboratory environment, even through the
others, the degree of attack will depend on the amount of corrosion is unbelievably small . For
relative activity of the two surfaces in contact. this reason , protection of all parts subject to
In any case, the more active or easily oxidized alternating stress is particularly important wher
surface becomes the anode and corrodes. In ever practical , even in environments that are
plated metal the possibility of dissimilar metal only mildly corrosive .
corrosion becomes a factor only if there are de
fects in the plating, which would allow moisture Fretting Corrosion
penetration and subsequently the forming of a
galvanic cell. Fretting corrosion is a limited but highly
damaging type of corrosion caused by a slight
Stress Corrosion vibration , friction, or slippage between two con
tacting surfaces which are under stress and
Stress corrosion, evidenced by cracking, is heavily loaded. It is usually associated with
caused by the simultaneous effects of tensile machined parts, such as the area of contact of
stress and corrosion . Stress may be internal or bearing surfaces, two mating surfaces, and
applied. Internal stresses are produced by non bolted or riveted assemblies. At least one of the
uniform deformation during cold working, by surfaces must be metal . In fretting corrosion , the
305
lipping movement at the interface on the con chapter 3 of this manual are suitable for detec
acting surface destroys the continuity of the tion of the depth of intergranular corrosion and
protective films that may be present on the stress corrosion cracks or other general defects
metallic surface . This action removes fine par in metal. Special methods to detect intergranular
icles of the basic metal. The particles oxidize corrosion using ultrasonics and eddy current
and form abrasive materials which further agi principles familiar to some specially trained senior
cate within a confined area to produce deep pits. Structural Mechanics have been developed.
Such pits are usually so located as to increase Knowledge of these more sophisticated methods
the fatigue failure potential of the metal. Frett is not required at the AMS 3 & 2 petty officer
ng corrosion is evidenced at an early stage by level. Any time there is even the slightest con
surface discoloration and by the presence of cern over the extent of intergranular corrosion
corrosion products in any lubrication present. damage or suspected damage , these specially
Lubrication and securing the parts so that they developed methods should be conducted by
are rigid are the most effective measures to pre qualified personnel.
Jent this type of corrosion .
Filiform Corrosion CORROSION ELIMINATION
Filiform corrosion is threadlike filaments of When corrosion of aircraft skin or structures

corrosion known as underfilm . Metals coated has been discovered , the first step to be taken
with organic substances, such as paint films, may
> >
should be the safe and complete removal of the
undergo this type of corrosion . corrosion deposits or replacement of the af
Filiform corrosion occurs independent of fected part. Which of these actions to be taken
Light, metallurgical factors in the steel, and depends upon the degree of corrosion, the ex
pacteria , but takes place only in relatively high tent of damage , the capability to repair or re
>
humidity , 65 to 95 percent. Although the place , and the availability of replacement parts.
threadlike filaments are visible only under clear Any part which has been damaged by corrosion
Lacquers or varnishes, they also occur with some should be replaced if continued use is likely to
frequency under opaque paint films. Filiform result in structural failure. Areas to be treated
corrosion can occur on steel , zinc , aluminum , for corrosion deposit elimination must be clean,
magnesium , and chromium plated nickel. unpainted , and free of oil and grease. Chips,
burrs, flakes of residue, and surface oxides must
Microbiological Corrosion be removed . However, care must be taken to
avoid removing, at the same time , too much of
Micro -organisms contained in sea water can be the uncorroded surface metal. Corrosion deposit
introduced into fuel systems by contaminated removal must be complete . Failure to clean any
fuel. These fungus growths attack, the sealing surface debris permits the corrosion process to
material used on integral fuel tanks . Under cer continue even after refinishing the affected
tain conditions, they can cause corrosion of areas .
aluminum probably by aiding in the formation When corrosion is present , any protective
of concentration cells. Residues resulting from paint films must first be removed to insure that
biological growth tend to clog fuel filters, and the entire corroded area is visible . After the
coat fuel capacity probes, giving erroneous fuel corrosion has been removed the extent of da
quantity readings. mage must be assessed. It is at this point that the
determination is made to repair or replace the
SPECIAL DETECTION METHODS affected part or to perform a corrosion correc
tion treatment. This treatment involves the neu
A variety of non destructive inspection tralization of any residual corrosion materials
methods may be utilized by the Aviation Struc that may remain in pits and crevices, and the
tural Mechanic in detecting flaws in metal. The restoration of permanent protective coatings and
metals inspection techniques discussed in paint finishes.
306
PAINT REMOVAL and stripping, insure that the aircraft is properly

grounded to dissipate any static electricity pro
Paint removal operations at the Organiza duced by the cleaning and stripping operations.
tional and Intermediate level of maintenance are Using approved tapes and papers, mask all
usually confined to small areas, or possibly a seals, joints, skin laps , bonded joints , etc. , where
whole panel. In all cases, the procedures out the paint remover may contact adhesives.
lined in the applicable Maintenance Instructions Apply the stripper liberally, and completely
Manual should be observed . General stripping cover the surface to a depth of 1/32 to 1/16
procedures are contained in Aircraft Cleaning inch , using a bristle brush . The stripper should
and Corrosion Control for Organizational and not be spread in a thin coat like paint, since it
Intermediate Maintenance Levels, NavAir 01 will not loosen paint sufficiently for removal
1A -509. and the remover may dry on the surface of the
metal , requiring a reapplication.
Materials Allow the stripper to remain on the surface
for a sufficient length of time to wrinkle and lift
All paint removers are toxic and caustic ; the paint, which may be from 10 minutes to
therefore, both personnel and material safety several hours, depending on both the tempera
precautions must be observed in their use. Per ture and humidity and the condition of the
sonnel should wear eye protection, gloves, and a paint coat being removed. Loosened paint may
rubber apron . be removed with fiber scrapers , bristle brushes,
PAINT REMOVER , SPECIFICATION MIL and rags. The surface should then be rinsed with
R -81294. - This is a new epoxy paint remover water to remove any residual stripper.
for use in the field . This remover will strip After rinsing the area thoroughly, wipe down
acrylic and epoxy finishes very satisfactorily. with rags wet with lacquer thinner or an ap
Acrylic windows, plastic surfaces, and rubber proved solvent cleaner such as Stoddard solvent .
products are adversely affected by this material. The next step is to remove all masking tape
This material should not be stocked in large and carefully strip away the remaining paint it
quantities as it ages rapidly , degrading the results covered , using rags slightly dampened with an
of stripping action . approved solvent cleaner such as methyl
Additional paint removers are discussed in ethyl -ketone (MEK). Use only nonmetallic
NavAir 01-1A-509 and NavAir 07-1-503 . Each scrapers to assist in removing persistent paint
remover has a specific intended use . For exam finishes .
ple, MIL-R-81294 is for removing epoxy finishes
but could be damaging to synthetic rubber,
while non -flammable water soluble paint re CORROSION REMOVAL
mover conforming to MIL-R- 18553 is usable in
contact with synthetic rubber. In all cases utilize After the paint has been removed from
the recommended remover that meets the re corrosion -damaged areas of metal surfaces, it is
quirements of the job being accomplished . necessary to remove all corrosion deposits be
fore an accurate assessment of damage can be
Procedures and Precautions made. The different corrosion removal processes
required by the various aircraft metals include
The stripping procedures provided in this sec chemical treatments to prevent or retard future
tion are general in nature . When stripping any corrosive attack . These chemical treatments are
aircraft surface, consult the applicable Mainte discussed as a part of the corrosion removal pro
nance Instructions Manual for the specific proce cesses in this section . Further chemical treat
dures to be used . ments are applied for the purpose of improving
Stripping should be accomplished outside paint adhesion if it is determined that the corro
whenever possible . If stripping must be done in a sion damage is tolerable and the affected parts
hangar or other enclosure , adequate ventilation may remain in service. Prepaint treatments are
must be assured. CAUTION : Prior to cleaning discussed in aa subsequent section of this chapter.
307
Corrosion Removal From Aluminum cessing of anodized surfaces, including corrosion

removal, should avoid unnecessary destruction
There are three types of aluminum surfaces of the oxide film .
nsofar as corrosion removal is concerned. They Aluminum wool, nylon webbing impregnated
are clad, anodized, and exfoliated. with aluminum oxide abrasive, or fiber bristle
CLAD ALUMINUM SURFACES .-Pure brushes are the approved tools for cleaning
aluminum has considerable corrosion resistance anodized surfaces. The use of steel wool, steel
compared to aluminum alloys, but has little or wire brushes, or harsh abrasive materials on any
no structural strength . It has been learned that aluminum surfaces is prohibited. Producing a
in extremely thin sheet of pure aluminum lami buffed or wire brush finish by any means is also
nated onto each side of an aluminum alloy sheet prohibited. Otherwise, anodized surfaces are
mproves the corrosion resistance with little im treated in much the same manner as other alumi
pairment of strength . The trade name of this num finishes.
aluminum laminate as originated by the Alumi EXFOLIATED SURFACES . -As previously
num Company of America is “ Alclad.” From described , exfoliation is a separation along the
his trade name the adjective “ clad” and the grain boundaries of metal and is caused by inter
verb " cladding" have been derived . Not all air granular corrosion . More severe procedures must
craft sheet aluminum is clad , especially those be observed when intergranular corrosion is pres
lloy sheets from which small brackets, gussets, ent . The mechanical removal of all corrosion
ittings, etc. , are made . The pure aluminum is products and visible delaminated metal layers
ery soft and the fabrication processes would must be accomplished in order to determine the
everely damage or destroy the clad surfaces. extent of destruction and to evaluate the remain
To remove corrosion from clad surfaces the ing structural strength of the component . Metal
corroded areas should be hand polished with scrapers, rotary files, and other necessary tools
household abrasives such as Bon Ami or Ajax, or are used to assure that all corrosion products are
with a specification metal polish , MIL-P-6888 . It removed and that only structurally sound alumi
the specification polish ) effectively removes num remains. Inspection with a 5 to 10 power
tains and produces a high-gloss, lasting polish magnifying glass, or the use of dye penetrant
on unpainted clad surfaces. During the foregoing (Chapter 3) , will aid in determining if all un
olishing operation, care must be taken to avoid sound metal and corrosion products have been
innecessary mechanical removal of the protec removed. When complete removal has been at
ive clad layer and the exposure of more sus tained , any rough edges should be blended or
ceptible, but stronger, aluminum alloy base . smoothed out even though this involves the re
If there is any superficial corrosion present , it moval of more metal . Grinding, where required,
hould be treated by wiping down with an inhib can best be accomplished by using rubber base
tive material such as the Chemical Surface Films wheels into which tiny particles of aluminum
Cor Aluminum Alloy , available under specifica oxide abrasives have been impregnated .
ion MIL - C -5541. (See Chemical Surface Treat Chemical treatment of exposed surfaces is ap
ment , this chapter . ) plied in the same manner as any other aluminum
ANODIZED ALUMINUM SURFACES. surface .
Anodizing is the most common surface treat Any loss of structural strength in critical areas
nent of nonclad aluminum alloy surfaces. The should be evaluated by cognizant aeronautical
luminum alloy sheet or casting is the positive engineers, particularly if the damage exceeds the
ole in an electrolytic bath in which chromic permissible limits established in the Structural
cid or other oxidizing agent produces an alumi Repair Manual for the aircraft model involved.
um oxide film on the metal surface. Aluminum
oxide is naturally protective , and anodizing Corrosion Removal From
nerely increases the thickness and density of the Iron and Steel
natural oxide film . When this coating is damaged
n service, it can only be partially restored by The most practicable means of controlling the
chemical surface treatments. Therefore, any pro corrosion of steel is the complete removal of the
308
corrosion products ( rust ) by mechanical means. ready for a protective paint coating.
Aluminum oxide abrasive paper or abrasive im
pregnated nylon webbing can be used . However, Corrosion Removal From Magnesium
residual iron rust usually remains in small pits
and crevices. Vacu -blasting with glass beads re Magnesium corrosion reprotection involves
moves nearly all rust and is the preferred the maximum removal of corrosion products,
method . the partial restoration of surface coatings by
There are approved methods for converting chemical treatment, and a reapplication of pro
active iron rust to phosphates and other protec tective coatings .
tive coatings ; however, most of these procedures After cleaning the surface and stripping the
require shop installed equipment and are there paint, if any , as much of the corrosion products
fore impractical in the field . Another disadvan as possible should be broken loose and removed ,
tage of chemically inhibiting iron rust is the using abrasive impregnated nylon webing or glass
danger of entrapping these chemicals in installed beads with the Vacu - Blast Dry Honing Machine.
assemblies where thorough flushing is difficult, Steel wire brushes, carborundum abrasives , or
thereby causing far more corrosion than was steel cutting tools should not be used . After the
originally present. corrosion has been removed , treat the surface
HIGHLY-STRESSED STEEL SURFACES. with Specification MIL-C-5541 , chemical treat
Any corrosion on the surface of highly stressed ment solution , as outlined in the section on
steel is potentially dangerous, and careful re Chemical Surface Treatment ( this chapter ); then
moval of the corrosion deposits is mandatory . restore the protective paint film .
Surface scratches or changes in the surface mo If extensive removal of corrosion products
lecular structure due to overheating can cause from a structural casting was involved , a decision
sudden failure. Removal of corrosion products from a structural engineer may be necessary in
must be accomplished by careful processing, order to evaluate the adequacy of the structural
using mild abrasive papers such as fine grit strength remaining. Structural Repair Manuals
aluminum oxide, or fine buffing compounds on for the aircraft models involved usually include
cloth buffing wheels. It is essential that the steel tolerance limits for dimensions of critical struc
surface not be overheated while buffing. After tural members and should be referred to if any
this careful removal of surface corrosion , protec question of safety of flight is involved .
tive paint finishes should be reapplied im
mediately . Corrosion Removal From Titanium
CADMIUM PLATED SURFACES . - As stated
previously, cadmium platings are still offering
> Titanium surfaces that show surface deteriora
sacrificial protection even when they show tion from the presence of salt deposits and im
mottling ranging from white to brown to black purities are cleaned with Specification P - D -680
on their surfaces. This discoloration should solvent (Stoddard solvent), then any corrosion is
never be removed for appearance sake alone . removed by hand using abrasive impregnated
Not until the characteristic color peculiar to nylon webbing and followed by final cleaning of
corrosion of the base metal appears should steps the surface with water emulsion cleaner solution
be taken. ( 1 part cleaner to 9 parts water).
Corrosion present should be removed by rub NOTE : The use of steel wool, iron scrapers,
bing lightly with stainless steel wool. Under no or steel brushes for cleaning or the removal of
circumstances should a wire brush, stainless or corrosion from titanium parts is prohibited .
otherwise, be used on cadmium plates surfaces
as these will remove more plating than corro MECHANICAL CORROSION
sion . After the corrosion has been removed the REMOVAL BY BLASTING
affected area should be swabbed with a chromic
acid solution and , after 30 to 60 seconds, rinsed Vapor blasting, soft grit blasting, and dry
with clean water and dried with clean cloths or vacuum blasting are the most effective mechani
low -pressure compressed air . The part is then cal methods of removing corrosion with the least
309
emoval of the metal . For use on assembled air

craft, a portable unit such as the Vacu -Blast
Hero Dry Honer is the most desirable .
VACU -BLAST Aero

Dry Honer
The VACU -BLAST Aero Dry Honer is a port

ble self-contained , lightweight unit utilizing the
iry vacuum return system . (Dry honing is the
only authorized blasting method of removing
orrosion on assembled aircraft .) With this
nachine the work is more visible and metal re
noval can be held to closer limits. The machine SUPPLY PRESSURE GAGE
s air operated and can be used in shore-based or
hipboard operations.
COMPONENTS . - The dry honing machine AIR EJECTOR
ABRASIVE PUMP
llustrated in figure 11-12 is composed of the RECLAIMING
SYSTEM
ollowing principal components mounted on a PNEUMATIC
Wo -wheel carriage assembly : SYSTEM

VIBRATING
SCREEN
( INSIDE )
1. Pneumatic system. MAIN
AIR SUPPLY
ABRASIVE CONNECTION
2. Control and regulator valves and gages. HOPPER
3. Abrasive hopper (storage tank ). (STORAGE TANK ) AIR FILTER
4. Aerator and feed tee . ABRASIVE

SUPPLY HOSE
MUFFLER
5. Abrasive supply and return hoses. AIR HOSE

( TO GUN ) DUST BAG
6. Suction bypass line. RAPPER
7. Blast gun assembly . AERATOR
AND FEED TEE
8. Gun set attachments .
9. Air ejector pump .
10. Abrasive reclaimer.
11. Dust collector . AM.59
12. Vibrating screen. Figure 11-12 . - VACU -BLAST -Dry honing machine
(back view) .
A hose rack and storage compartment are pro
-ided on the front of the dry honing machine
or storage of hoses, brushes, and accessories. variable pressure regulator is operated to adjust
Pneumatic System. -The pneumatic system the air supply to the desired pressure before
ncludes a main air supply connection at which entering the airhose to the blast gun assembly.
s attached the external compressed -air supply , This pressure is indicated on the blast pressure
nterconnecting tubing, and air filter with a gage adjacent to the pressure regulator.
rain cock for removal of liquid from the com Abrasive Hopper ( Storage Tank ).- The abra
pressed air, and an air ejector pump that creates sive storage tank is conical in shape to effect
he necessary vacuum to return the used abrasive direction of flow of abrasive. It is removed by
rom the blast gun assembly to the filter bags. release of two spring clamps. The normal capac
The dry honing machine operates satisfactorily ity of the storage tank is 5 pounds of abrasive
on air pressures ranging from 80 to 100 psi and material.
ir-flows ranging from 80 to 90 cfm . Aerator and Feed Tee . - The aerator and feed
Control and Regulator Valves andGages.- The tee located at the bottom of the storage tank is
upply pressure gage indicates the compressed designed to aerate the abrasive in the storage
ir supply pressure. The 150 -pound maximum tank and feed is to the blast hose leading to the
310
blast gun. The aeration is effected by mixing of BLAST CONTROL VALVE

air with the fine abrasive.
When the fine abrasive is aerated , debris par
ticles which may be mixed with the abrasive ,
settle to the bottom of the storage tank. The
AIR Sonia
abrasive is then drawn through a metering valve , ABRASIVE
from a point a short distance above the bottom
of the tank , thus preventing recirculation of the
debris particles. The abrasive then flows through ABRASIVE
RETURN HOSE
the feed tee into the supply hose .
Abrasive Supply and Return Hoses. -The
abrasive supply hose is a 20 -foot length of 5 /8
inch ID transparent plastic hose , which permits
direct observation of abrasive flow . It is attached
Hid
to the aerator and feed tee and conveys aerated
abrasive to the blast gun assembly . The abrasive BLAST GUN ASSEMBLY
return hose is 20 feet long and returns used abra
sive and debris from the blast gun assembly to
the abrasive reclaiming system .
Suction Bypass Line . - The suction bypass line
is designed to remove abrasive from the blast
hose when the machine is shut off in order to
eliminate hose surging when blasting is started
again . One end of this line is connected to the
feed tee opposite the blast hose connection , and
the other end of the line extends up into the
storage tank . This line terminates in the storage
tank above the abrasive level , and the open end
DY
is protected from the abrasive by an interior
baffle. When blasting stops, the exhauster re
mains in operation to suck air backwards
through the blast gun assembly, abrasive supply
hose, feed tee, and bypass line , conveying any
abrasive in the hose back into the storage tank .
When blasting, airflow is reversed and the bypass
line insures a balanced pressure between the
storage tank and the feed tee housing so that
abrasive will fall freely through the feed tee into
the blast hose .
Blast Gun Assembly.- The blast gun assembly
( fig. 11-13 ) consists of a hand -held gun , blast
control valve, nozzle assembly , and connections
for air, abrasive supply, and return hoses. The
blast gun assembly draws the abrasive material MBALIMALI PRILI
from the abrasive supply hose , accelerates the CUTAWAY VIEW
abrasive through the blast nozzle, and directs it
against the workpiece. This is accomplished
through the gun, which employs an eduction
principle whereby compressed air is expended AM.60
through an air jet to create a low pressure area in Figure 11-13. -Blast gun assembly.
the gun housing , and by connecting the abrasive
311
BRUSH ACCESSORIES
RUBBER
PAD
FLAT SURFACE INSIDE CORNER OUTSIDE CORNER EDGE CLEANING IRREGULAR SURFACE
AM.61
Figure 11-14 . -Gun set attachments.
supply hose to the gun housing at the point filter bag type dust collector onto which the
where this low pressure area is created . reclaimer is mounted .
Gun Set Attachments. The three brushes and Dust Collector. -The dust collector consists of
an irregular surface attachment, illustrated in a number of cloth filter bags so arranged that
figure 11-14, are provided with the dry honing dust laden air rising from the reclaimer cyclone
machine, and permit blasting of most surfaces. is ducted to the bottom of the dust collector
Additional care must be exercised with the in housing where it must pass through the cloth
side and outside corner brushes to avoid the loss filter bags before being discharged through the
of abrasive . The irregular surface attachment will exhauster. Filter bags are periodically cleaned by
conform to most irregularities.
a manually operated bag -shaking mechanism to
Air Ejector Pump. - The air ejector pump remove the accumulated dust which drops to the
creates the necessary vacuum to return the abra dust collector box for disposal.
sive from the blast gun assembly through the -
return hose to the abrasive reclaimer, carrying Vibrating Screen.-The vibrating screen , incor
the dust still farther to the cloth filter bags in porating a permanent magnet to remove steel
the dust collector. particles, is located between the reclaimer
Abrasive Reclaimer . - The abrasive reclaimer is cyclone and the abrasive storage tank . The
mounted directly above the abrasive storage screen is sufficiently fine to remove any oversize
tank and consists essentially of a cyclone separa foreign particles from the abrasive. The vibrating
tor into which abrasive and debris ( from the screen is exposed for cleaning and inspection by
abrasive return hose) enter . The angle at which dropping the abrasive storage tank. It is vibrated
entry is made imparts a cyclonic, or circular, by an air-driven vibrator mounted at the center
action to the airstream , causing the abrasive to of the screen on a supporting frame, the amount
drop out of suspension . The conveying airstream of vibration being preset by an orifice in the air
leaves the separator through the top, carrying line.
with it extremely fine particles of dust which are ABRASIVE . - Although blasting equipment
no longer usable as abrasive. The reclaimed abra may use many types of abrasives, only glass
sive itself drops to the bottom of the separator beads are authorized for the removal of mild to
and then back through a vibrating screen section medium corrosion from naval aircraft. Glass
into the abrasive storage tank . Air and dust leav beads are manufactured of high grade optical
ing the reclaimer cyclone pass into the cloth crown glass, soda lime type.
312
OPERATING PROCEDURES.- The operating

procedures listed in this section are general in
nature. The dry honing machine must be used
with care , and only by a qualified operator.
NOTE : A face shield must be worn at all
times while operating the dry honing machine.
To operate the dry honer, fill the abrasive
hopper with a full charge of the correct size
abrasive material. Less than full abrasive charges
may be used for touchup work or for dry honing 000
either highly corroded or relatively small areas
of steel. Contaminated abrasives should be
thrown away after completion of the dry honing
operation . No less than one-half charge (2 1/2
pounds) should ever be used .
After filling the machine with the correct
abrasive, turn the regulator adjusting screw to
the full open position, then turn on the external
air supply valve. Set the pressure regulator to the AM.62
desired pressure by placing the gun against a Figure 11-15 .-- Proper operation of gun.
scrap piece of metal or rubber and operating the
gun. The blast pressure can then be adjusted hours of operation, shut off the air supply to the
with the machine in operation. machine and shake down the filter bags by
Hold the blast gun firmly against the surface swinging the dust bag rapper down and sharply
to be dry honed and press down on the blast returning it to the normal position. Repeat this
control valve. Move the gun in a smooth pattern rapper action for 20 quick strokes. After shaking
of overlapping strokes, advancing approximately down the filter bags, empty the dust box .
3/4 inch at each pass. Dwell times must be kept Four -Hour Intervals. -Open the drain cock at
at the minimum necessary to produce complete the bottom of the air filter and drain moisture
corrosion removal . every 4 hours, or whenever visible . Additional
CAUTION : Excessive dwell times could re maintenance and lubrication requirements are
sult in overheating of the material and/or excess defined in NavAir 17-5BM- 1 .
ive metal removal. CAUTION : Care must be taken to prevent
Smoothest reversal of direction at the end of damage to the plastic air filter bowl. Mechanical
each pass is made by moving the brush in a small damage or contact with common solvents will
circular path as shown in figure 11-15 , so that cause it to shatter when pressurized . If necessary
the bristles roll smoothly from one direction to to clean the bowl , use only water or a mild
the other. To prevent loss of abrasive, fully re detergent solution .
lease the blast control valve each time the dry LIMITATIONS . — The dry honing machine
honing operation is stopped and/or before the described in the aforementioned sections can
gun is raised from the surface . cause damage to aircraft components and sys
INSPECTION AND MAINTENANCE. tems if improperly used . Small quantities of
Certain components to the dry honing machine abrasive may be expected to escape from the
require inspection and maintenance at calendar blast nozzle during normal use ; therefore, the
or operating intervals. The two maintenance equipment must not be used in areas or under
actions listed below are usually performed by conditions where the abrasive may contaminate
the operator. systems or components.
CAUTION : The main air supply must be 1. Do not use on engines, gear boxes, or
turned off before performing any maintenance other oil lubricating systems.
action . 2. Do not use on fuel , hydraulic, or oxygen
Two -Hour Intervals. At the end of each 2 system components.
313
3. Mask vents of the above listed systems surface should be painted soon after treating if
vhen blasting near them to prevent possible con best results are to be expected .
amination . Soluble salt residues remaining on the surface
4. Use only on exterior surfaces or parts after treatment will accelerate corrosion and can
which have been removed from the airframe to cause blistering of paint finishes. Thus, complete
prevent possible contamination of interior areas . rinsing with fresh water following the chemical
5. Do not use on airframes skins or structural treatment is very important. Flush the chemical
parts which are exposed to over 500° F in serv with free -flowing water only . DO NOT wipe the
ce . area with a damp cloth or brush as this will
6. Do not blast Metallite or honeycomb deteriorate or remove the chemical conversion
anels.
NOTE : Corrosion PREVENTIVE mainte
mance is documented on a Support Action
Form , while corrosion maintenance that is con
idered as TREATMENT must be documented
on the Maintenance Action Form so that a rec
ord of extensive corrosion rework will exist and
be available for any Aircraft Logbook entries
hat may be required . Danny
CORROSION DAMAGE LIMITS
The term "corrosion damage limits” refers to

he amount of metal which may be removed
rom a corroded part and still maintain the re
uired safe margin of strength and function .
Vhen removing corrosion , maintenance per
onnel must be very careful not to remove more REF. NO. NOMENCLATURE
of the metal than is absolutely necessary to 1 OUTER CYLINDER
2 ACTUATOR PISTON
nsure complete removal of corrosion. Figure 3 ACTUATOR BODY
1-16 illustrates the maximum corrosion depths 5
4 TORQUE ARMS
5 WHEEL
llowed on the various components of the nose 6 FORK
anding gear on one late model aircraft. 7 STEERING UNIT
8 PISTON
Damage which exceeds those limits specified
n the applicable Structural Repair Manual or CHROME PLATE
che Corrosion Control section of the applicable
Maintenance Instructions Manual necessitates re MAXIMUM CORROSION DEPTH
placement of the affected part if actual struc REF. NO . MATERIAL MAX DEPTH
ALUMINUM 0.015
Eural repair of the damage is not possible or 2 CHR PLATED STEEL 0.003
Feasible . 3 ALUMINUM 0.030
4 ALUMINUM 0.030
5 MAGNESIUM 0.030
CHEMICAL SURFACE TREATMENT 6 HEAT RESISTANT STEEL 0.010
7 HEAT RESISTANT STEEL 0.010
8 HEAT RESISTANT STEEL 0.010
Chemical conversion coatings will increase 8* CHROME PLATED
HEAT RESISTANT STEEL 0.004
corrosion resistance and improve paint adhesion .
After cleaning and removal of any surface
oxides, aluminum and magnesium should be
created with MIL -C -5541 chemical treatment .
These coatings are often damaged during aircraft AM.63
maintenance or are contaminated by grease, oil, Figure 11-16. -A-5 nose gear-maximum corrosion
or other foreign matter. Therefore , the treated depths.
314
Chapter 11 -CORROSION CONTROL
coating, which is sensitive to abrasion prior to 3. Rinse thoroughly as with the aluminum
fully drying. treatment and allow to air dry prior to applying
CAUTION : Personnel should wear goggles, protective paint finishes.
aprons, and rubber gloves when using solutions
of MIL-C-5541 . Some magnesium parts in later model aircraft
have been originally protected by a proprietary
(held under patent) electrolytic process. The
Chemical Conversion of “ HAE ” process is identified by the brown to
Aluminum Alloys mottled gray appearance of the unpainted sur
face . “ DOW 17 ” coatings will appear as a green
The procedure to be used for the chemical to grayish green color. These coatings are gen
conversion of aluminum alloys is as follows: erally thicker than those applied by immersion
or brush method such as MIL-C-5541 . The elec
1. Insure that the surface is clean. trolytic finish cannot be restored in the field .
2. Brush MIL-C-5541 solution on areas to be Therefore, when failure of the coating occurs,
treated . Repeat application of fresh solution any corrosion should be removed and the bare
until a uniform irridescent yellow to brown magnesium should be touched up with MIL
color is produced , then discontinue brushing and C - 5541 chemical treatment solution . Care
allow the solution to remain on the metal for should be taken to minimize removal of the elec
about 1 minute . trolytic coatings as they afford greater protec
3. Rinse the complete area with fresh water. tion than the replacement coatings.
4. Allow to air dry (usually not more than 1
hour) before priming. A powdery coating indi
cates poor rinsing or failure to keep the surface CORROSION
wet during the treatment. If this occurs , the CONTROL KIT
treatment should be repeated .
A corrosion control kit is available for operat
NOTE : Chemical treatments conforming to ing activities and is especially useful for small
Specification MIL-C- 5541 are not all the same detachments. The kit is primarily designed for
composition and therefore should be prepared use in treating small areas of corrosion and con
for use according to the particular manufac tains all the necessary materials and equipment .
turer's instructions. A compartmented case provides orderly storage
of materials. Most materials are identical to
materials discussed in this chapter.
Chemical Conversion of A maskant material is provided to use in paint
Magnesium Alloys stripping operations. The maskant is squeezed
around the area to be stripped and forms a dam
Procedure for the chemical conversion of to protect areas where paint remover is not de
magnesium alloys is as follows: sired . The maskant must be high enough to con
tain the paint remover . After the paint is lifted
1. Insure that the surface is clean . or softened, the loosened paint , paint remover ,
2. While the surface is still wet , brush on and maskant material are removed by using the
MIL -C -5541 chemical treatment solution. Con micarta scraper, which is provided in the kit , to
tinue application of fresh solution on the metal work the material toward the center of the en
until a uniform light brown color is obtained . circled area . The residue is then scraped into a
NOTE : The solution for magnesium is the disposable plastic bag . A washing bottle is pro
same as used for aluminum and is made up ac vided for rinsing the area following stripping and
cording to the manufacturer's aluminum treat chemical treatment of the corroded area .
ment instructions. The solution will react much The epoxy polyamide primer packages are
more rapidly with magnesium than with alumi supplied in plastic squeezable bags. At least 1
num . hour prior to use , the two components are
315
mixed by pressing the inner bag of component final recommendations for refinishing require
wo , so that it breaks, and then kneading the ments when the aircraft is scheduled for Progres
uter bag until the two components are sive Aircraft Rework at the Depot level of main
horoughly mixed . When ready to use , the top tenance .
of the bag is opened and the primer brushed on .
Topcoat is available in aerosol spray cans .
All other materials are common to corrosion SURFACE PREPARATION
maintenance personnel . Complete instructions
or appropriate reference to the Cleaning and Much of the effectiveness of any paint finish
Corrosion Control Manual is provided in each kit and its adherence depends on the careful pre
with the arrangement of materials supplied in paration of the damaged surface prior to touch
he kit printed on the back of the instruction up. The procedures to be used in paint and
cheet. Materials in the kit may be replenished corrosion removal have been described pre
rom standard stock as necessary to maintain the viously. The touchup paint should overlap onto
kit . the existing good paint finish . The touchup ma
terials will not adhere properly to glossy
finishes. Also, any edges of the existing film will
AIRCRAFT AND COMPONENT PAINTING show through the overlap unless they are
AND PAINT TOUCHUP smoothed out .
To break the gloss of existing finishes and to
The amount of paint touchup accomplished feather (smooth out) the edges for overlap , scuff
at the Organizational and Intermediate level will sand , using 300 to 400 aluminum oxide paper.
ary widely with the activity involved , the avail Following sanding, a water rinse is used to re
ability of facilities, and the area of operations . move the abrasive residues.
The primary objective of any paint finish is Next , all sanded areas and exposed bare metal
he protection of exposed surfaces against dete surfaces are wiped down with 1 -BUTANOL
Fioration. There are secondary reasons for partic (normal butyl alcohol).
alar paint schemes ; the reduction of glare by Remove any loosened seam sealants in the
nonspecular coatings, the use of white or light area to be touched up and replace as necessary .
colored high -gloss finishes to reduce heat absorp (See Sealants and Sealing Practices in this chap
ion , camouflage or high visibility requirements, ter. ) Also , resecure any loose rubber seals, using
or special identification markings. There is sel the type adhesive specified in the applicable
om justification for repainting for appearance Maintenance Instructions Manual .
ake only . A faded or stained , but well-bonded , The area to be painted is then outlined with
Daint finish is better than a fresh touchup treat tape and masking paper as shown in figure
ment improperly applied over dirt, corrosion 11-17. This protects the adjoining surfaces from
products, or other contaminants. over- spray and unwanted paint buildup .
Complete refinishing, particularly under field
conditions, should be restricted to those areas
where existing paint finishes have deteriorated, TOUCHUP PROCEDURES
through age and exposure, until they fail to per
Form their protective function . Renewal of spe In the past, it was necessary to identify the
cial finishes and markings should also be re specific surface finish (paint system ) applied to
stricted to those situations where the purpose of an aircraft at the time of manufacture or re
he special finish is not being served. However, work. Each surface finish ( nitrocellulose lacquer,
maintenance and repair of paint finishes at the acrylic lacquer, and epoxy ) required a specific
Organizational and Intermediate level is ex touchup procedure that was compatible with the
remely important, from the evaluation of initial present finish . Failure to properly identify the
paint finishes at the time of aircraft receipt, present surface finish and apply the specific
Chrough the constant surveillance and mainte touchup procedures, usually resulted in wasted
nance of finishes during a service tour, to the manhours and material.
316
the primer will exhibit unsatisfactory properties,

REMOVE MASKING BEFORE such as poor adhesion , poor chemical resistance,
APPLYING TOP COAT or inadequately dried film .
с. с
For mixing, pour the specified amount of part
1 into an empty container, then slowly pour
part 2 into the container , stirring constantly .
CAUTION : Always add part 2 to part 1 .
To thin the primer for spraying, add 1 1/2
parts thinner, Specification MIL - T -19588 , to 2
parts primer. The thinned primer should be
stirred thoroughly, strained, and allowed to
stand 1 hour prior to use . If necessary the thin
ning ratio may be varied slightly to obtain the
proper spraying viscosity . The 1 -hour standing
time is necessary to permit the components to
enter into chemical reaction , shorten drying
time , reduce cratering, preclude part 2 from
“ sweating out ” or migrating, and to allow any
bubbles (formed while stirring) to escape .
To apply the primer, insure that the surface
AM.64 to be primed has been cleaned, chemically
Figure 11-17 . -Masking prior to paint touchup. treated , and prepared for spraying as previously
described in this section . Apply a wet coat of
epoxy primer to 1 mil thickness and allow to
To preclude this and more effectively control dry from 1 to 2 hours. One hour is sufficient
corrosion, a standardized paint system for Or when temperature and humidity range is ideal .
ganizational and Intermediate level painting and
paint touchup has been promulgated by the
Naval Air Systems Command . This system con Acrylic Lacquer Topcoat
sists of an improved epoxy primer, Specification (MIL-L-81352)
MIL - P -23377B and an acrylic topcoat , Specifica
tion MIL - L -81352, and is compatible with all of This acrylic lacquer is used as a general pur
the various systems presently used in naval air pose external coating for metal surfaces. It is
craft . applied directly over the epoxy -polyamide
primer. It is available in all colors for touchup
Epoxy -Polyamide Primer and insignia marking directly over all paint sys
(MIL - P - 23377B ) tems presently employed on naval aircraft.
To thin the acrylic lacquer topcoat for spray
The epoxy-polyamide primer is supplied as a ing, mix 1 volume of lacquer with approxi
two -part kit , each part of which must be stirred mately 1 1/2 volumes of thinner. The thinner
or shaken thoroughly before mixing. One part used with this lacquer is composed of equal
contains the pigment, ground in an epoxy ve parts by volume of toluene and xylene. The
hicle, while the other part is composed of a clear exact thinning ratio must be determined by the
polyamide solution which functions as a hardner user and adjusted to the prevailing temperature,
for the epoxy solution. This primer is supplied relative humidity , and type of spraying equip
by various manufacturers. Mix only as much ment being used . Increasing the xylene portion
primer as needed , as the storage life of the promotes better flowout and reduces dry spray
primer is limited after mixing. CAUTION : Do but also prolongs drying time.
not substitute part 1 or part 2 from another After thinning the acrylic lacquer to spraying
manufacturer. Established mixing ratios supplied viscosity, it should be applied in two spray coats
by the manufacturer must be followed ,otherwise with a 30 -minute air-dry interval between coats.
317
Table 11-1. - Acrylic topcoat application, possible defects and methods for correction.
Problem Cause/Correction
Webbing . 1. Insufficient thinning .

Dry spray . 1. Insufficient thinning .
2. Increase the proportion of the slower
evaporating xylene in the xylene
toluene mixture .
Orangepeel or poor flowout. 1. Insufficient thinning

2. Increase the proportion of the slower
evaporating xylene in the xylene
toluene mixture .
3. Poor spray technique.
Slow drying . 1. Increase the proportion of faster
evaporating toluene in the xylene
toluene blend.
Bleeding through or lifting of 1. Allow epoxy primer to dry longer,

primer . 2. First coat of lacquer topcoat was
applied too wet ( first coat can also
be misted on) .
3. Too rich solvents used to reduce lacquer
topcoat; decrease proportion of
thinner .
The total dry film thickness of the acrylic top gaged in mixing and spraying paint and/or pri
coat should be 0.8 to 1.2 mils. mers. Gloves and aprons should also be used to
To apply insignia and/or squadron markings prevent skin contact. The mixing and applica
over the acrylic topcoat, begin masking after the tion of paints and primers should be done in
coating has dried tack -free. Apply the tape with well -ventilated spaces only.
a minimum of pressure to avoid marking and Paint touchup in the field is a difficult task .
possible damage to the topcoat. The insignia Table 11-1 lists some of the problems en
and/ or markings are then applied directly over countered during paint application , the most
the topcoat. NOTE : Do not use epoxy primer probable cause, and methods for correction .
when repainting or doing touchup work over
Specification MIL-L-81352 acrylic lacquer top
coat.
Polyurethane Finish Systems
When painting insignia and/or squadron mark
ings over all other paint systems, use the epoxy In its present search for better quality protec
primer and then overcoat with the acrylic lac tive finishes, the Naval Air Systems Command
quer . has authorized that certain aircraft receive ex
CAUTION : The materials used for painting terior polyurethane finishes.
and paint touchup are toxic and flammable. Pre The polyurethane finish is available in kits
cautions must be taken to assure respiratory consisting of a two-component material - resin
( face mask) and eye protection for personnel en and catalyst. The touchup kits are prethinned
318
and ready for use when mixed in accordance radome or leading edge coatings are in bad con
with the instructions in the kit . dition, they should be stripped completely and
One- gallon kits are available for production recoated with epoxy primer and acrylic topcoat
type spraying. They consist of 3 1/2 quarts of as a temporary measure. If schedules and condi
resin and 1 pint of catalyst, providing a 7 to 1 tions permit adequate curing of elastomeric
mixing ratio . Thinning with a suitable reducer, coatings, these original coatings may be re
as specified by the manufacturer, is required to placed .
obtain a proper spraying viscosity . The repair kits are normally bought open pur
Polyurethane finishes are applied over epoxy chase to insure that fresh materials are available.
polyamide primer which has been allowed to dry They should be stored in a cool place or refrig
for 1 hour. The primer is then scuffed with erated , as heat accelerates aging. Stripping of
400-grit paper to remove any dry, rough areas fiberglass surfaces should be in accordance with
which could adversely affect the leveling of the current maintenance instructions. Elastomeric
polyurethane film . Apply one even , light top coatings are toxic and flammable and must be
coat of polyurethane, allow to dry for 15 to 45 used with care .
minutes, then apply a final full topcoat. Insignia
white polyurethane has a slight translucent
characteristic and may require the application of
one additional coat to obtain an adequate AIRCRAFT PAINTING EQUIPMENT
shadow -free finish . The total topcoat dry film AND TECHNIQUES
thickness should not exceed 1.5 mils . Glossy
colors will normally dry in approximately 6 to 8 The AMS is called upon many times to use his
hours. Camouflage colors will dry in approxi skill and knowledge in the painting of aircraft.
mately 4 to 5 hours. This type of work is normally performed during
preventive maintenance inspections or when air
Enamel Finishes craft painted surfaces warrant touchup repairs.
New aircraft normally assigned to an activity
Most enamel finishes used on aircraft surfaces are usually required to have the following mark
are baked finishes that cannot be touched up ings painted on the aircraft : Squadron designa
with the same materials in the field . tion ( example, VP - 8 ); modex number (example,
Minor damage to conventional enamel finishes 5 ) ; unit identifying letter or letters (example ,
ordinarily used on engine housings is repaired by LC ); and at times a large bureau aircraft serial
touching up with epoxy topcoat material or air number (example, 149673 ). (See fig. 11-18 . )
drying enamel . Since types of paints were discussed earlier in
the chapter, only the equipment and techniques
Elastomeric Rain Erosion in painting aircraft are covered in this section .
Resistant Coating (MIL -C -7439)
PAINTING EQUIPMENT
Elastomeric coatings are used as a coating
system to protect exterior laminated plastic Spray Guns
parts of high -speed aircraft , missiles, and heli
>
copter rotary blades from rain erosion in flight. The spray gun atomizes the material to be
They offer good resistance to weather and sprayed and the operator directs and controls
aromatic fuels in addition to rain erosion . Excel the spray pattern through manipulation and
lent adhesion is obtained after a 7-day drying minor adjustments of the spray gun . Spray guns
period. are usually classed as either suction -feed or
Repairs to these coatings in the field are im pressure-feed type. The types can be divided by
practicable due to this long curing time. Kits are two methods-by the type of container used to
available for repair of coatings where limited hold the paint material, and by the method in
touchup is required . These kits contain a primer, which the paint is drawn through the air cap
neoprene topcoat , and antistatic coating . If the assembly .
319
LC
149673
5 NAVY
VP -8
AM.418
Figure 11-18 . - Aircraft markings.
SUCTION -FEED TYPE.-The suction -feed caused by a fleck of dried material in the nozzle,
spray gun is designed for small jobs. The con or the fluid needle packing may be too tight. It
tainer for the paint is connected to the spray may also be caused by a bent fluid needle, a
gun by a quick -disconnect fitting, as illustrated broken fluid needle spring, or the wrong size
in figure 11-19. The capacity of this container is fluid needle for the fluid tip .
approximately 1 quart. The fluid tip of this type AIR LEAKAGE . - Air leakage is a result of
spray gun protrudes through the air cap as improper setting of the air valve. This may be
illustrated in figure 11-20. The air pressure rush caused by a bent valve stem , a broken spring, or
ing by the fluid tip causes a low -pressure area in a damaged valve or valve seat.
front of the tip . This causes paint to be drawn JERKY OR FLUTTERING SPRAY . - Jerky
up through the fluid tip where it is atomized or fluttering spray is caused by obstructed fluid
outside the cap by the air pressure. passage , loose tip or damaged seat, and air in the
PRESSURE - FEED TYPE . - The pressure -feed fluid line . The air can be inducted from several
type spray gun is designed for use on large jobs points on the equipment, loose packing nut or
where a large amount of spray materials is to be dried out packing, loose or damaged coupling
used . With this type, the spray material is sup nut, loose or damaged fluid tube, lack of suffi
plied to the gun through a hose from a pres cient material, and cup tipped too far. (See fig.
surized tank. This spray gun is designed to 11-21 . )
operate on a high volume and low air pressure. FAULTY SPRAY PATTERNS. - Faulty spray
This type of spray equipment eliminates evapo patterns, their causes, and how to correct them
ration of the volatile substances of the mixture are shown in figure 11-22 .
before striking the surface since the paint and air CLEANING SPRAY GUNS .. - Spray guns
are mixed internally ; in other words, a wetter should be cleaned immediately after each use .
coating is applied . To clean the suction type gun, empty the con
tainer and pour in a small quantity of thinner or
Spray Gun Maintenance suitable solvent. Draw the thinner or suitable
solvent through the gun by inserting the tube
FLUID LEAKAGE . - Fluid leakage at the into the container of cleaning fluid . Move the
front of the gun is an indication that the fluid trigger constantly to thoroughly flush passage
needle is not seating properly . This may be ways and the tip of the fluid needle. Remove the
320
AIR CURRENTS CREATE A VACUUM
며
2
FLUID TIP PROTRUDES ABOVE AIR CAP
SUCTION OR GRAVITY FEED CAP
FLUID TIP IS FLUSH WITH

AIR CAP
-AIR CAP
82PRESSURE FEED CAP

o
AM.420
CUP IS PART Figure 11-20. -Suction and pressure fluid tips and
air caps.
O
O OF GUN
in the cleaning fluid as stated above for the suc

AM.419 tion type gun .
Figure 11-19. –Suction-feed type spray gun . NOTE : Do not immerse an entire spray gun
in cleaning materials such as cleaning solvents
and thinners. These materials dissolve the oil
air cap and soak it in solvent. If this does not from leather packings and cause the gun to have
clear the small holes in the air cap , remove the an unsteady spray .
paint material, using a toothpick or broomstraw. LUBRICATION OF SPRAY GUNS .-The fol
Do not use wire or other metal objects which lowing parts of a spray gun require frequent lub
may cause permanent damage to the air cap . rication : Fluid needle packing, air valve stem ,
To clean a pressure-feed gun , proceed as fol and trigger bearing screw . Remove the fluid
lows : Back off the fluid needle adjusting screw . needle packing before using the gun and soften
Release the pressure from the pressure tank by it with oil. The fluid needle spring should be
means of the relief or safety valve. Hold aa cloth coated with a specified grease. ( See fig. 11-24.)
over the air cap and operate the gun trigger. This
forces the spray material back into the pressure Air Compressors
tank . (See fig. 11-23 .) Remove the fluid hose
from the gun and pressure tank . Attach hose In order to use spray guns , a source of com
cleaner to hose and run thinner or suitable sol pressed air is necessary . Figure 11-25 illustrates
vent through to clean the hose. Place the air cap two types of air compressors - a portable unit
321
OBSTRUCTED LOOSE TIP OR LOOSE PACKING

FLUID PASSAGE DAMAGED NUT OR DRIED
SEAT OUT PACKING
LOOSE OR
DAMAGED
COUPLING NUT
LOOSE OR LACK OF
DAMAGED SUFFICIENT
FLUID TUBE MATERIAL
IN CUP
1
CUP TIPPED
TOO FAR -
AM.421
Figure 11-21 . -Causes of jerky or fluttering spray .
and a stationary unit. Both types are in common Air Regulators

use .
The air regulator (or transformer ) is used to
The portable unit consists of an electric regulate the amount of air pressure to the spray
motor (or gasoline engine) for driving the unit , a gun and to clean the air. The air delivered to the
compressor, storage tank , automatic unloader regulator always contains some oil from the
mechanism , and wheels and handle for moving compressor and some water caused by condensa
the unit . tion, and many particles of dirt and dust.
Air regulators are equipped with a pressure
The stationary unit consists of an electric valve and pressure regulating screw . This makes
motor, compressor, storage tank, centrifugal
-> it possible to regulate exactly the pressure
pressure release, pressure switch , and mounting delivered to the spray gun and prevents any pres
feet. sure fluctuations. The air must pass through a
sack or cleaner before it leaves the regulator.
Some of the more common compressor This cleaner is contained in the long cylindrical
troubles are illustrated in figure 11-26 . part of the regulator.
322
PATTERN CAUSE CORRECTION

DRIED MATERIAL IN SIDE
A
PORT " A " RESTRICTS PAS
SAGE OF AIR THROUGH IT . DISSOLVE MATERIAL IN SIDE - PORT
RESULT : FULL PRESSURE WITH THINNER . DO NOT POKE IN
OF AIR FROM CLEAN SIDE ANY OF THE OPENINGS WITH METAL
PORT FORCES FAN PATTERN INSTRUMENTS .
IN DIRECTION OF CLOGGED
SIDE .
DRIED MATERIAL AROUND

THE OUTSIDE OF THE B
FLUID NOZZLE TIP AT
POSITION " B " RESTRICTS
THE PASSAGE OF ATOMIZ IF DRIED MATERIAL IS CAUSING
ING AIR AT ONE POINT THE TROUBLE , REMOVE AIR NOZ
THROUGH THE CENTER ZLE AND WIPE OFF FLUID TIP ,
OPENING OF AIR NOZZLE USING RAG WET WITH THINNER .
AND RESULTS IN PATTERN TIGHTEN AIR NOZZLE .
SHOWN . THIS PATTERN
CAN ALSO BE CAUSED BY
LOOSE AIR NOZZLE .
REDUCING AIR
PRESSURE WILL
CORRECT CAUSE С
(1) . TO COR
RECT CAUSE ( 2 ) ,
D
A SPLIT SPRAY OR ONE THAT IS HEAVY
OPEN MATERIAL
000
ON EACH END OF A FAN PATTERN AND CONTROL " D " TO
WEAK IN THE MIDDLE IS USUALLY FULL POSITION
CAUSED BY ( 1 ) TOO HIGIL AN ATOMIZ BY TURNING TO
ING AIR PRESSURE , OR ( 2 ) BY ATTEMPT LEFT . AT THE
ING TO GET TOO WIDE A SPRAY WITH THIN SAME TIME TURN Ti
MATERIAL . SPRAY WIDTH AD
JUSTMENT " C " TO RIGHT .
THIS WILL REDUCE WIDTH
OF SPRAY BUT WILL COR
RECT SPLIT SPRAY PATTERN
TO CORRECT
CAUSE ( 1 )
( 1 ) DRIED OUT PACKING AROUND MATE BACK UP E
RIAL NEEDLE VALVE PERMITS AIR TO GET KNURLED NUT
INTO FLUID PASSAGEWAY . THIS RESULTS ( E ) , PLACE
IN SPITTING . TWO DROPS OF
MACHINE OIL
( 2 ) DIRT BETWEEN FLUID NOZZLE SEAT ON PACKING ,
AND BODY OF A LOOSELY INSTALLED REPLACE NUT
FLUID NOZZLE WILL MAKE A GUN SPIT . AND TIGHTEN
WITH FINGERS
SPITTING
( 3 ) A LOOSE OR DEFECTIVE SWIVEL NUT
ON SIPHON CUP OR MATERIAL HOSE CAN
CAUSE SPITTING ,
ONLY . IN AG
GRAVATED CASES ,
REPLACE PACKING .
Mac
F
TO CORRECT CAUSE ( 2 ) , REMOVE

FLUID NOZZLE ( F ) , CLEAN BACK
OF NOZZLE AND NOZZLE SEAT IN
GUN BODY USING RAG WET WITH
THINNER , REPLACE NOZZLE AND
DRAW UP TIGHTLY AGAINST BODY .
TO CORRECT CAUSE ( 3 ) TIGHTEN

OR REPLACE SWIVEL NUT ( G) .
A FAN SPRAY PATTERN THAT IS HEAVY
IN THE MIDDLE , OR A PATTERN THAT INCREASE PRESSURE FROM YOUR
HAS AN UNATOMIZED " SALT -AND - PEPPER " AIR SUPPLY . CORRECT AIR PRES
EFFECT INDICATES THAT THE ATOMIZ- SURES ARE DISCUSSED ELSEWHERE
ING AIR PRESSURE IS NOT SUFFICIENTLY IN THIS CHAPTER .
HIGH .
AM.422
Figure 11-22 -Faulty spray patterns and how to correct them .
323
| - FORCE MATERIAL
BACK INTO TANK AUTOMATIC UNLOADER
MECHANISM
2- DISCONNECT ELECTRIC MOTOR
allows outfit to run
FLUID HOSE idle after maximum
also supplied pressure is reached
with gas engines
3- CONNECT HOSE TO HOSE
CLEANER
HOSE CLEANER
4- FILL CLEANER
WITH A SOLVENT
5- OPEN CLEANER
VALVES TO
CLEAN HOSE
6 - CLEAN OUT
TANK
NOTE :
RELEASE PRESSURE
IN TANK BEFORE
BLOWING BACK
‫الع‬ Ry CENTRIFUGAL PRESSURE
RELEASE
MATERIAL : allows compressor to
run free until normal
A - SHUT OFF AIR TO TANK PRESSURE speed is attained
FEED TANK
B- OPEN RELIEF VALVE PRESSURE SWITCH
stops motor when
C - LOOSEN THUMB SCREWS maximum pressure
is reached
D- OPEN LID SLIGHTLY
AM.423
Figure 11-23. -Cleaning pressure -feed spray gun .
OIL HERE
AM.425
Figure 11-25. -Air compressors.
Im
Air regulators are equipped with two gages.

One gage shows the pressure on the main line
while the other shows the pressure to the spray
FLUID NEEDLE gun . A complete compressor and air regulator
PACKING installation is shown in figure 11-27 .
FLUID NEEDLE AIR VALVE
SPRING PACKING Spray Gun Technique
Proper spray gun technique is acquired and

AM.424 developed through knowledge of the equipment
Figure 11-24 . - Spray gun lubrication points. and experience of the operator. The spray gun
324
CARBON ON PISTON
DIRTY VALVES
VALVE ASSEMBLY INFERIOR PISTON RINGS

IMPROPERLY INSTALLED
WORN WRIST PIN
PAINT COVERED CYLINDER
DIRTY CHECK
CLOGGED AIR STRAINER
VALVE
" FROZEN " BEARINGS
WORN MAIN BEARINGS

TH
LEAKAGE LACK OF OIL OR DIRTY OIL

IN AIR LINE
AM.426
Figure 11-26 . - Possible compressor troubles.
SLOPE TOWARDS TAKE OFF FROM

DRAIN LEG
TOP OF LINE
PIPE RECOMMENDATIONS
Ž AND 2 H.P. QUTFITS AIR REGULATOR
MIN. Ź IN . UP TO 50 FT.
OVER 50 FT . 3 IN
AND OIL AND
WATER EXTRACTOR
TAKE OFF
3 AND 5 H. P. OUTFITS
Min. IN . UP TO 200 FT .
DRAIN LEG
MAIN AIR OVER 200 FT. I IN .
LINE
AIR REGULATOR
AND OIL AND
WATER EXTRACTOR
DRAIN HERE
DAILY
DRAIN HERE DAILY
AM.427
Figure 11-27 . -Compressor and air regulator installation .
325
should be held so that the spray is perpendicular

to the area to which the finish is being applied .
Great care should also be taken to insure that RIGHT
the prescribed distance from the gun to the

work is maintained .
The gun should be held from 8 to 10 inches
from the work for spraying lacquer and 6 to 8 3. RELEASE
1. BEGIN
inches for spraying enamels , depending on the STROKE
TRIGGER
2. MOVE GUN BEFORE
width of the spray pattern . Generally , with a THEN PULL IN STRAIGHT LINE -
COMPLETING
narrow pattern , the gun is held the farther TRIGGER
STROKE
distances from the work ( 10 inches for lacquer WRONG
and 8 inches for enamels) .
In general , a distance of less than 6 inches is DO NOT
ARCING CAUSES
UNEVEN
undesirable, since the paint will not atomize ARC STROKE APPLICATION
properly, and " orange peel" will result. A
distance of more than 10 inches is equally
undesirable, since dried particles of paint will
strike the surface and cause “ dusting” of the
finish .
Examples of correct and incorrect spray gun SURFACE
techniques are shown in figure 11-28 .
The distance the spray gun is held from the SURFACE
work is very important ; however, there are other
factors which must be considered and mastered .
The manner in which the gun is held and
operated is illustrated in figure 11-28 . Move the WRONG
arm and body with the gun to keep the spray METHOD
perpendicular to the surface. Avoid pivoting or
any circular movements of the wrist or forearm
CORRECT
which will bring the gun closer to the surface METHOD
when directly in front of the body .
It is important to " trigger " the gun in order
to avoid an uneven coat building up at the
beginning and end of a stroke . Triggering is the AM.428
technique of starting the gun moving toward the Figure 11-28.-Correct and incorrect methods of
area to be sprayed before the trigger is pulled , spraying.
and continuing the motion of the gun after the
trigger has been released . turning to the left gives a fanshaped pattern.
Care must be taken to avoid too much As the width of the spray is increased , more
overlapping on each pass of the gun or an material must be allowed to pass through the
uneven coat will result . The rate of stroke gun to get the same coverage on the increased
should be such as to produce a full, wet , even area . To apply more material to the area , the
coat. operator should turn the fluid needle adjustment
Once the job is started it must be carried ( fig. 11-29 ) to the left. If too much material is
through to completion without stopping. applied to the surface , turn the fluid needle
SPRAY GUN ADJUSTMENTS . - Figure 11-29 adjustment to the right.
illustrates the principal parts of a typical spray In normal operation of the spray gun , the
gun , including the various adjustment points. wings on the air cap are adjusted to the
The spreader adjustment dial is used in adjusting horizontal position, as illustrated in figure
the width of the spray pattern . By turning the 11-30 . This provides a vertical fan -shaped
dial to the right, a round pattern is obtained ; pattern, given maximum coverage as the gun is
326
14. FLUID NEEDLE 11. FLUID TIP

ADJUSTMENT 10. AIR CAP
8. SPREADER 5. SPRAY HEAD

ADJUSTMENT DIAL 9. SPREADER ADJUSTMENT VALVE
VIDONDA
7. FLUID NOZZLE
6. HOLES IN
2. AIR SPRAY CAP
VALVE 12. FLUID INLET
13. FLUID NEEDLE
1. TRIGGER
4. GUN BODY ASSEMBLY
3. AIR INLET
AM.429
Figure 11-29 . - Sectional view of typical spray gun .
moved back and forth parallel to the surface 1. Too high an air pressure alone causes
being painted . dusting of finish and rippling.
2. Too low an air pressure , coupled with too
SPRAYING PRESSURES . -Normally ,
-
the high fluid pressure , causes orangepeel.
AMS will be concerned with spray painting 3. Too high fluid pressure alone causes
lacquer, enamel , and epoxy materials. The orangepeel and sags.
correct air and fluid pressures used with these 4. Too low fluid pressure alone causes
materials vary and are important in all spray dusting.
painting applications . There are several pitfalls
of incorrect pressures, some of which are listed When using 20 -foot air and fluid pressure
below : hoses , maintain a pressure of approximately 45
327 .
-
damage or the use of paint removers has
loosened existing sealants.
Conditions surrounding the requirements for
use of sealants govern the type of sealants to be
used . Some sealants are exposed to extremely
high and/or low temperatures. Other sealants are
in contact with fuels , lubricants, etc. Therefore,
it is necessary that sealants be used which have
been compounded for that particular type of
-WING
usage . These sealants are supplied in different
consistencies and rates of cure . The basic types
of sealants are classified in three general
categories – Pliable Sealants , Drying Sealants , and
Curing Sealants.
PLIABLE SEALANTS
AM.430
Figure 11-30.-Spray gun nozzle. These sealants are referred to as one-part and
are supplied ready for use as packaged . They are
solids and change little, if any , during or after
psi at the spray gun for lacquer and 50 psi for application . Solvent is not used in this type.
enamel and epoxy . This pressure is measured at Therefore, drying is not necessary ; and except
the gun. Sufficient pressure must be maintained for normal aging, they remain virtually the same
at the main line pressure regulator to obtain the as when first packaged , neither hardening nor
above pressures and to compensate for the shrinking. The adhesion to metal, glass, and
pressure drops encountered if additional lengths plastic surfaces is excellent. Pliable sealants are
of hose are employed . The pressure at the gun used around high -usage access panels and doors,
should be rechecked if the main line pressure is and in areas where pressurization cavities must
changed for any reason . Fluid tank pressure for be maintained .
lacquer should be 8 to 12 psi. A 3 -pound
increase above these figures should be used in DRYING SEALANTS
the case of enamel and epoxy . A proportionate
increase in pressure for lacquer and epoxy Drying sealants set and cure by evaporation of
should be allowed for additional lengths of hose the solvent. Solvents are used in these sealants to
up to 50 feet maximun. One-pound fluid provide the desired consistency for application.
pressure may be added for each foot of height of Consistency or hardness may change little or
the gun from the fluid tank level. Make frequent much when this type sealant dries , depending on
checks with a test gage of air pressure at the gun. the amount of solvent it contains. Shrinkage
upon drying is another important consideration ,
and the degree of shrinkage is dependent upon
SEALANTS AND SEALING PRACTICES the proportion of solvents.
Sealants are used to prevent the movement of CURING SEALANTS

liquid or gas from one point to another. They
are used in an aircraft to maintain pressurization Catalyst- cured sealants have obvious
in cabin areas , to retain fuel in storage areas, to advantages over drying sealants because they are
achieve exterior surface aerodynamic transformed from a fluid or semifluid state into
smoothness, and to weatherproof the airframe. a solid mass by chemical reaction or physical
Sealants are used in general repair work in the change, rather than by evaporation of a solvent.
field and for maintenance and restoration of A chemical catalyst or " accelerator" is added
seam integrity in critical areas if structural and thoroughly mixed just prior to sealant
328
applications. Heat may or may not be employed

to speed up the curing process. When using a
catalyst, accurate proprotioning and thorough
mixing of the two components are vitally
important to assure a complete and even cure .
IN UNIT
APPLICATION OF SEALANTS
Application of sealants varies according to
20W
time element , tools required , and the method of
application. However, the following restrictions
apply to all sealant applications :
1. Sealant should be used within the
approximate application time limits specified by
the sealant manufacturer.
2. Sealant should not be applied to metal
A IM
which is colder than 70° F. Better adhesion is

obtained and the applied sealant will have less
L
SELF -POWERED
tendency to flow out of place while curing if the SPRAYER
CAUTION: CONTENTS
metal is warmed to a temperature of 90° F to UNDERPRESSURE
READ CAREFULLY
100 ° F before the sealant is applied . OTHER
ON BACK CAUTIONS
PAN EL
3. Sealant should be discarded immediately
when it becomes too stiff to apply or work
readily . Stiff or partially cured sealant will not
wet the surface to which it is to be applied as
well as fresh material and , consequently, will not
have satisfactory adhesion .
4. Sealant should not be used for faying
surface applications unless it has just been MPODO NOT FILL ABOVE THIS LINE
RTA
removed from refrigerated storage or freshly NT:D N ON
THA 4 W O OT TILT MTON
mixed . COMPN 5° HE SPR S
.
LETE UN N
IT IN UPRAYINPGOS
IGH ITIO
T N
While the use of sealants on aircraft surfaces
has greatly increased over the past few years,
application methods have been mostly through
the use of brushes, dipping, extrusion guns, and
spatulas. The spraying of sealants has been a PREVAL "
CLEANPRODUC T CONTAINER
IMMEDIATELY AFTER USE
recent development. Sealant, MIL -S -81733,
Type III, is the one most extensively used for
>
spray application. If Type III sealant cannot be

procured , sealant MIL - S -8802, Class A, may be
used by thinning to a sprayable consistency by AM . 1224
the addition of toluene. Figure 11-31 . -Spray applicator
kit.
In addition to standard spray type equipment ,
special application types have been developed
for the occasional or small touchup job . There ( sealant container ). The essential features
are many types available. Figure 11-31 illustrates include the power unit with a pushbutton spray
one type which consists of a self - contained cap on top and on the bottom, and a screw -type
power unit with an attached spray bottle lid which attaches to the sealant container. A
329 :
>
AM. 1225
Figure 11-32. -Sealant applied to aircraft exterior surfaces.
dip tube extends from the bottom of the power complished by brush coating the contacting
unit into the sealant container. The power unit , surfaces with the specified sealant. The applica
which may be procured separately , contains tion of the sealant should be made immediately
three ounces of propellant. The sealant before fastening the parts together .
container (spray bottle ) can also be procured Careful planning and arrangement of work
separately. and equipment are necessary in order that faying
Figure 11-32 illustrates where sealant is surface seals on large assemblies may be closed
applied to protect some of the most corrosion within the application time limit of the sealant.
prone areas on an A-6 aircraft. The sealant is Once the sealant has been applied, the parts
applied using spray, spatula, and brush methods. must be joined , the required number of bolts
When pressure sealing an aircraft, the sealing
>
must be torqued, and all the rivets driven within
materials should be applied in such a manner as this time limit .
to produce a continuous bead , film , or fillet over
> When insulating tape has been installed
the sealed area. Air bubbles , voids, metal chips, between the faying surfaces to prevent dissimilar
or oily contamination will prevent an effective metals contacts , pressure sealing should be
seal. Therefore, the success of the sealing accomplished by fillet sealing.
operation depends upon the cleanliness of the Fillet sealing is accomplished by spreading the
area and the careful application of the sealant specified sealant along the seam with a sealant
materials . injection gun. The sealant should be spread in
There are various methods of pressure sealing approximately 3 -foot increments. Before
joints and seams in aircraft. The applicable proceeding to the next increment, the applied
Structural Repair Manual will specify the portion of the fillet should be worked in with a
method to be used in each application. sealant spatula or tool. (See fig . 11-33 .) This
The sealing of a faying surface is ac working of the sealant is done to fill in all voids
330
in the seam and to eliminate as many air bubbles Sealing Compound (MIL-S-8802 )
as possible . The leak -free service life of the
sealant is determined by the thoroughness and This temperature-resistant (-65° to +250° F) ,
care used in working out the air bubbles. two - component, synthetic rubber compound is
used for sealing and repairing fuel tanks and fuel
cell cavities. It is produced in the following
classifications:
NON -METALLIC SPATULA Class A-Sealing material , suitable for brush

‫ا‬
‫جمن‬
‫ر‬
application .
‫ن‬
‫ا‬
Class B - Sealing material, suitable for applica

tion by extrusion gun and spatula .
MASKING Class C - Sealing material , suitable for faying
TAPE surface sealing.
Dash numbers after the classification code

indicate the application time in hours allowed
before the curing cycle will have progressed to
the point where it is no longer feasible to apply
that particular batch of sealant.
Class A dash numbers are -1/2 and -2 .
Class B dash numbers are -1/2 , -2, and -4 .
AM.65
Class C dash numbers are -20 and -80 (8 hours
Figure 11-33 . - Applying sealant. of application time with the remaining time
allowed for working the material).
Example : Class A-2 designates a brushable
After the sealant has cured to a tack -free material having an application time of 2 hours.
condition , the fillet should be inspected for any Class B- 1 / 2 designates an extrusion gun material
remaining air bubbles. Such air bubbles should having an application time of 1/2 hour. Class
be opened up and filled with sealant. C-20 designates a faying surface sealant with an
When a heavy fillet is required it should be application time of 8 hours and a working life of
applied in layers and the top layer should fair 20 hours.
with the metal .
Injection sealing is the pressure filling of Sealing Compound (MIL - S -81733)
openings or voids with a sealant injection gun .
Joggles should be filled by forcing sealant into This accelerated , room temperature curing
the opening until it emerges from the opposite synthetic rubber compound is used in sealing
side . Voids and cavities are filled by starting metal components on weapons and aircraft
with the nozzle of the sealant injection gun at systems for protection against corrosion . This
the bottom of the space and filling as the nozzle sealant contains a percentage of magnesium
is withdrawn . chromate as a corrosion inhibitor. The classifica
Fasteners such as rivets , Rivnuts, screws , and tion of this sealant compound is of the following
small bolts should have a brush coat of sealant types :
over the protruding portion on the pressure side.
Washers should have a brush coat of sealant on Type I -For brush or dip application .
both sides. Split type grommets should have Type II -For extrusion application , gun or
sealant brushed into the split prior to installa spatula.
tion. After installation, fillets should be applied Type III -For spray gun application.
to both the base of the grommet and the Type IV -For faying surface application , gun
protruding tube on the pressure side. or spatula.
331
The following dash numbers are used to

designate the maximum application time in
hours : When using any material designated as flam
mable, all sources of ignition must be at least 50
rs
Iype l - Dash numbe are -1/2 and -2 . feet away from the location of the work . Toxic
Iype Il- Dash numbers are - 1/2, -2 ,and -4 . vapors are produced by the evaporation of
solvents and /or the chemical reaction taking
Type III -Dash number is -1.
Iype IV - Dash numbers are -12 and -24 . place in the curing sealants. When using sealants
in confined spaces such as fuel cells, fuselage or
PRECAUTIONS wing sections, table or bench operations, etc.,
SAFETY adequate local exhaust ventilation must be used
to reduceco the vapors below the maximum
Many of the sealants listed above may be allowable ncentration , and kept at that level
flammable and / or may produce toxic vapors .
until repairs have been completed. Do not eat or
smoke when working with sealants.
332
CHAPTER 12
LINE OPERATIONS AND MAINTENANCE
Line operations and maintenance is one of the involved in towing, spotting, and securing
most important responsibilities of the AMS3 and aircraft.
AMS2 . Line operations and maintenance is the
term used to describe that work which is TAXI SIGNALMAN
necessary to insure that operational aircraft, ( PLANE DIRECTOR )
aircraft equipment , and aircraft support equip
ment are ready and safe for the type of flight or Any time an aircraft is ready to taxi from the
operations for which they are scheduled . This flight line or is returning to the line for spotting,
work is performed on a flight line, flight deck, it is directed by one or more taxi signalmen as
or other place normally used to park aircraft. It necessary .
is usually performed prior to or between The taxi signalman should assume and
scheduled flights, without removal of the maintain a position where he can see the pilot's
aircraft from the flight schedule . eyes at all times. If it is necessary for him to lose
Line operations and maintenance includes sight of the pilot's eyes in changing positions, or
aircraft handling, daily preflight and postflight for any other reason , he should signal the pilot
inspections, servicing, lubrication , jacking, and
> to stop until he has taken up his new position.
the use and maintenance of various types of The taxi signalman has a definite position to
aircraft support equipment . Some of these maintain when directing aircraft, calculated to
>
functions are
are not normally performed by give him all possible advantages. His position
personnel of the AMS rating , however, many when directing single -engine aircraft should be
operating activities use third class petty officers slightly ahead of the aircraft and in line with the
of the AM and AD ratings as Plane Captains. As left wingtip. An alternate position , in line with
a plant captain , the AMS may be required to the right wingtip , may be used when it is
perform all of these functions. necessary to clear obstructions .
When directing aircraft with side -by -side
seating, such as is found on multiengine aircraft,
his position is forward of the left wingtip. He
AIRCRAFT HANDLING has no alternate position since the pilot of a
multiengine aircraft sits on the left-hand side of
Although aircraft handling is primarily the the cockpit . When directing multiengine aircraft
responsibility of the AB rating, all aircraft in obstructed areas, an assistant taxi signalman
maintenance personnel should be familiar with may be used on the right wingtip . The assistant
proper ground handling techniques . Practically taxi signalman will signal the aircraft taxi
all structural damage to aircraft on the ground is signalman on the left wingtip . The taxi
caused by carelessness or lack of knowledge of signalman must always be in a position to see
proper ground handling procedures. the assistant taxi signalman and the pilot's eyes.
This section describes the duties of the taxi Figure 12-1 illustrates the taxi signalman's
signalman and discusses some of the problems position directing aircraft.
333
of the Armed Forces so that there will be no

misunderstanding when a taxi signalman of one
service is signaling a pilot from another. These
signals are for the most part given with the
hands ; at night plastic wands attached to regular
flashlights are used . The signals should be
definite and precise to eliminate any possible
misunderstanding and to inspire the pilot's
confidence in the taxi signalman .
The Airman Manual, NavPers 10307 -C ,
chapter 12 , lists and explains the standard taxi
signals used by all branches of the Armed Forces
for the operation and movement of aircraft on
the ground , including helicopter landing, take
off, and ground handling signals.
Aircraft handling procedures and signals
peculiar to shipboard operations which would be
of interest to plane captains and other
maintenance personnel assigned to the flight
deck are listed in the CVA /CVS NATOPS
Manual . A similar manual is provided for the use
of personnel assigned to Amphibious Assault
Ships (LPH ).
The General Information section of each
AM . 190 aircraft Maintenance Instructions Manual lists
Figure 12-1 . - Position of taxi signalman. the necessary special signals required for that
specific aircraft and not covered by the standard
When towing aircraft, the same positions are taxi signals.
used as for directing an aircraft moving under its
own power. The taxi signalman must keep the
occupant of the cockpit (usually the plane TOWING AIRCRAFT
captain ), the driver of the towing vehicle, and
assistant taxi signalmen in sight at all times. Towing aircraft can be a hazardous operation ,
Aircraft being taxied on land within 25 feet causing damage to the aircraft and injury to
of obstructions must have a taxi signalman at personnel, if done recklessly or carelessly. The
each wingtip . If an obstruction is present on one following paragraphs outline the general proce
side only , a man at that wingtip is required . dure for towing aircraft; however, specific
Aircraft must not be taxied at any time within 5 instructions for each model of aircraft are
feet of obstructions. Aircraft being taxied on detailed in the General Information section of
water must not be taxied closer than 50 feet to the applicable Maintenance Instructions Manual
obstructions except in mooring or docking and should be followed in all instances.
procedures or when dictated by nature of the NOTE : Most naval aviation activities issue
mission. Extra precaution is necessary when specific instructions concerning aircraft towing.
directing aircraft at night. The taxi strip and These instructions usually contain the composi
parking area should be inspected for workstands tion of the tow crew , tow tractor speed , and
and any other mobile equipment which can various other instructions concerning local
damage an aircraft. conditions. These instructions must be complied
with .
Standard Taxi Signals Aircraft are generally moved (towed) by a
tow crew . The tow crew is usually composed of
Standard taxi signals are used by all branches a tractor driver, a plane captain ( to man the
334
Chapter 12 -LINE OPERATIONS AND MAINTENANCE
cockpit) , and one man to watch for clearance at for use with only one type of aricraft. The
each wingtip and the tail . universal tow bar is designed to tow a number of
The man assigned to operate the brakes must different types of naval aircraft.
be thoroughly familiar with the particular type The universal tow bar (NT - 4 ) which is now
aircraft. His main function is to operate the being used by the Navy is shown in figure 12-2 .
brakes in case the tow bar should fail or come This tow bar is designed with sufficient tensile
unhooked. He must also be familiar with the strength to pull most aircraft, but is not
operation of various systems such as the ejection intended to be subjected to torsional of twisting
seat, power canopy, wing fold , and the safety loads . Although the universal tow bar has small
precautions associated with each. wheels that permit it to be towed behind the
The men assigned to observe the wings and tow tractor when going to and from an aircraft,
tail should proceed at their assigned stations as it will suffer less damage if it is loaded aboard
the aircraft is being towed. It is the respon the tow tractor and hauled to the aircraft. When
sibility of these men to keep a sharp lookout for the bar is attached to the aircraft, all engaging
obstructions and signal the tractor driver in time devices should be inspected for damage or
to prevent collisions. Signals may be given with malfunctions before moving the aircraft.
the hands or a whistle . The universal tow bar, when used for
Only qualified personnel should attempt to nosewheel towing ( fig. 12-3 ) is secured to the
tow an aircraft. Driving a tow tractor requires nosewheel axle by means of two pins and a
specialized training as well as a valid Navy tensioning chain and knob .
driver's license . To mount the universal tow bar on a
nosewheel, the tensioning knob is loosened and
Tow Bars the chain is released . After the bars are lifted
and the pins inserted into the axle ends, the
There are two types of tow bars- universal chain is drawn tightly through the bar and
and special . Special tow bars are those designed hooked in the slot which is provided to lock it in
CHAIN STOWAGE HOLES
TENSIONING CHAIN
AXLE PIN LOCK
HOOK
ESQ
TENSIONING KNOB
SAFETY PIN
AXLE PIN
AM.193
Figure 12-2. -Universal tow bar ( NT-4).
335
Dindor
Q
SEX
SYS
NG
CAYOUN
VASE
23 wi
ri i
ni ner
AM . 194
Figure 12-3.-NT-4 tow bar installed on nosewheel.
place. Tightening the tensioning knob then rings by means of hooks which are mounted on
applies enough pressure to hold the bar pins in the ends of the bars. A spring-loaded safety pin
the ends of the axles . secures the hooks in the rings.
Holes are provided in one bar to stow the pin Special tow bars are designed to be secured to
on the loose end of the tensioning chain . Placing the aircraft in various ways. The information
this pin in one of these stowage holes eliminates contained in the applicable Maintenance Instruc
the possibility of damaging the chain by tions Manual should always be followed when
dragging it on the deck as the aircraft is being attaching special tow bars to an aircraft.
towed . When towing the aircraft, the towing vehicle
The universal tow bar may be used to tow speed must be reasonable , and all persons
aircraft from rings mounted on the fuselage or involved in the operation must be alert. Only
landing gear. The tow bar is secured to these reliable, competent personnel should be assigned
336
.
Chapter 12 - LINE OPERATIONS AND MAINTENANCE
to operate tow tractors. When the aircraft is determine how the aircraft should be secured .
spotted, the brakes of the tow tractor should The tiedown procedures provided in the General
not be relied upon to stop the aircraft . The man Information and Servicing volume of the
in the cockpit should be alert for the possible applicable Maintenance Instructions Manual
need of aircraft brakes along with those of the include normal weather tiedown procedures and
tow tractor . heavy or severe weather tiedown procedures.
NOTE : Before towing an aircraft, insure that Some MIM's also include special tiedown
all landing gear ground safety locks are installed. procedures to be used when jacking an aircraft
Landing gear ground safety locks are pins and aboard ship while the ship is underway. Figure
clamps which are used to insure that the landing 12-4 illustrates the severe weather and shipboard
gear does not retract accidentally while ground tiedown arrangement for the A-6A aircraft. One
handling the aircraft. tiedown per fitting is designated as sufficient for
normal weather tiedown .
SPOTTING AIRCRAFT
Carrier Aircraft Based
An aircraft can be spotted on the flight line Aboard Ship
under its own power , by the use of a tow
tractor, or manually , by pushing. If it is spotted
> Aircraft aboard carriers are tied to pad eyes
manually, thethe handling crew should be which are welded into the flight deck and the
instructed not to push on any control surfaces hangar deck . These pad eyes are quite similar to
or other areas on the aircraft which are stenciled the pad eyes found embedded in the concrete
" no push ," as damage to the aircraft may result. parking areas of naval air stations .
Regardless of the method used to spot the The tiedown of aircraft aboard aircraft
aircraft, a qualified man must be in the cockpit carriers is practically the same as that specified
to operate the brakes. for aircraft based ashore . However, since the
A qualified signalman should also be used to carrier is subject to movement , the aircraft must
>
direct the aircraft to its assigned spot. be tied down securely as soon as it is parked .
Sometimes the spots will be painted on the Most carriers require the use of at least three
parking ramp, but in many cases he will have to tiedowns as soon as it is parked and more if it is
be familiar with the parking area so he can spot to be left unattended . The total number of
the aircraft in the best position for securing it to tiedowns necessary depends upon the operating
the tiedown pad eyes. The position of the taxi conditions. The General Information section of
signalman during spotting is the same as for the aircraft Maintenance Instructions Manual
taxiing, and he should be able to see the eyes of contains information concerning tiedown points,
the man in the cockpit at all times. type tiedowns to be used , and the number of
When spotting aircraft at night, extra tiedowns to be used on each aircraft . The Air
precautions should be taken to insure that the Department of the carrier may have additional
parking area is clear of all workstands and other instructions which may require more tiedowns
equipment. Assistant taxi signalmen should be than specified in the applicable Maintenance
used at each wingtip to insure that the path is Instructions Manual.
clear and that there is no danger of hitting other The tiedown commonly used aboard carriers
aircraft or obstructions. is illustrated in figure 12-5 . The chain type
When the aircraft is spotted in its proper tiedown (TD- 1 ) is used to secure aircraft aboard
position , the brakes should be applied and held ships and ashore. It has a rated capacity of
until the main landing gear wheels are chocked . 10,000 pounds. Each TD - 1 tiedown weighs
about 12 pounds.
AIRCRAFT TIEDOWN The TD- 1 tiedown consists of a chain and a
tensioning device. The chain is inserted into the
The tiedown of aircraft is a very important tensioning device and locked by a spring-loaded
part of ground handling. When tying down lock . After the chain is locked in the tensioning
aircraft, the expected weather conditions will device the tiedown may be tightened by turning
337
TENSIONING
GRIP QUICK
S RELEASE
IGHT LEVER
o o
C ADJUSTABLE
HOOK
ASSEMBLY
CHAIN
LOCK
CHAIN
POCKET
o
MECHANISM BODY
TENSIONING AND
QUICK - RELEASE
F MECHANISM
CHAIN AND
HOOK
ASSEMBLY
AM.198
Figure 12-5 .-- Chain type tiedown-TD-1 .
at one end and have an eye splice at the other.

Put one end through the tiedown ring or point
on the aircraft and the other end through the
pad eye , thread the whipped end through the
eye splice and tighten up on the line . Then
AM . 1210 secure the line, using half hitches or a rolling
Figure 12-4 . - Tiedown arrangement-A-6A. hitch together with half hitches.
CAUTION : When manila line is used , it
should be carefully adjusted to provide for
the tension nut in the direction of the arrow on shrinkage due to moisture. However, excessive
the end of the nut . The TD- 1 tiedown is released line slack which would allow shifting of the
by pulling the release lever up and back . aircraft should be avoided .
The number of tiedown lines or chains to use
Land and Carrier Aircraft when securing the aircraft is governed by the
Based Ashore anticipated weather conditions. The normal and
heavy weather tiedown procedures are given for
Aircraft ashore on naval air stations are tied each type aircraft in the applicable Maintenance
down on concrete parking areas equipped with Instructions Manual .
ringlike fittings called pad eyes. These pad eyes Most aircraft are equipped with surface
are installed when the concrete is poured and are control locks which should be engaged or
installed flush with the surfaces of the concrete installed whenever the aircraft is secured . Some
The aircraft to be tied down is spotted in the aircraft control surfaces are locked by simply
parking area in the best position for full moving a lever and aligning the controls in the
utilization of the pad eyes. If high winds are neutral position . However , some aircraft require
anticipated , they should be headed into the the use of gust locks such as the one shown in
wind. The aircraft may be tied down with chain figure 12-6. Since the method of locking
type tiedowns or manila line. controls will vary on different type aircraft,
When manila line is used , it should be whipped check the applicable Maintenance Instructions
338
Chapter 12- LINE OPERATIONS AND MAINTENANCE
INSTALLATION
APULL PIN RETRACTING LEVERS APART AND
LEG BRACE MOVE ASSEMBLY AFT UNTIL ANCHOR PINS LINE
UP WITH HOLES UNDER LEG BRACES. RELEASE
LEVERS ALLOWING ANCHOR PINS TO ENGAGE.
BUOVE STICK INTO ALIGNMENT WITH SLOT IN
STICK LOCK FORK. INSTALL PIN .
NO GAP HERE WHEN CSLIDE SPRING LOADED COLLAR AFT ON
PINS ARE IN RUDDER LOCK BAR. HOOK YOKE PIN OVER HOOK
ON LEFT RUDDER PEDAL ARM, RELEASE COLLAR .
DADJUST RUDDER PEDAL CRANK TO TRIM RUDDER
ANCHORING WITH FIN
PIN
INSTALL AILERON
BATTENS AT WIND
VELOCITIES OF 60
KNOTS .
CONTROLS LOCK ASSY
It
PIN AILERON
BATTEN
RETRACTING LEVERS
STICK LOCKING FORK

la
PEDAL ADJUSTING m
moro
CRANK
- SPRING LOADED
-
-
-
-
COLLARS
YOKE PIN
RUDDER LOCK BAR -HOOK ON LEFT RUDDER

PEDAL ARN
AM.197
Figure 12-6 . - Surface control locking device and batten installation .
Manual for the proper installation or engaging hangar, the aircraft should be turned so that it
>
procedure. faces into the wind . All covers and guards which
When extremely high winds are anticipated protect the canopy , wing butts, air intakes and
and the aircraft cannot be moved into the other parts of the aircraft should be installed .
339
These protective covers should also be installed

if the aircraft is to remain secured on the line for
any length of time.
A special heavy -duty tiedown ( fig. 12-7 )
commonly referred to as a full power chain L
assembly is used to secure the aircraft to the
deck while the engine is being run up to full
power for check and adjustments.
The full power tiedown assembly consists of a
coupler, chain and a deck fitting. The coupler
adapts to the catapult holdback fitting on the
aircraft. The chain is made of welded links and is
attached to the coupler and deck fitting with
removable shackles. The deck fitting assembly
permits 360 degrees horizontal travel around the AERO FULL POWER
CHAIN ASSENNY
deck and 0 to 45 degrees vertical angle from the
deck. The deck fitting assembly adapts to the
various types of pad eyes.
TAIL TIEDOWN
Only specifically tested and designated pad
eyes should be utilized for high power turnups. CATAPULT
HOLDBACK
In other words , all pad eyes that will FITTING DECK FITTING
accommodate the full power chain assembly

should not be considered strong enough to
withstand the stress of a full power turnup.
When carrier aircraft are tied down with their
wings folded , a jury strut which gives extra COUPLER
support to the folded part of the wing must be
installed . When aircraft must be left on the flight
deck of a carrier in extremely heavy weather
(winds in excess of 100 knots), the wings should AM . 199
be left in the spread position . Figure 12-7 . - Full power tiedown .
Aircraft are spotted and tied down aboard the
carrier with just inches between each aircraft.
Therefore, it is of utmost importance that they and protective devices. Protective covers are
be secured properly to prevent any excessive usually provided for canopies, engine air intakes
movement when the ship is maneuvering or and exhausts , wing and vertical stabilizer fold
encountering heavy seas . Excessive movement of areas, and various other ducts or inlets.
just one aircraft may cause serious damage to Protective covers should be tightly installed .
several aircraft. All straps and locking devices should be secured .
Loose ends should not be left to blow in the
USE OF COVERS AND SHROUDS wind . The loose end of a strap , particularly one
with a metal clip or buckle, will severely damage
Protective covers and shrouds are provided by the finish of an aircraft.
the aircraft manufacturer for each aircraft. Care should be taken when handling protec
These covers are designed to protect various tive covers to insure that grit or trash does not
areas and components of the aircraft from the collect on the inner liner. The installation of a
elements, to protect personnel, and to prevent dirty cover may scratch the finish of the aircraft
foreign objects from entering vital areas during or severely damage transparent plastic canopies
periods of extended inactivity. The applicable and glass windshields.
Maintenance Instructions Manual contains in All protective covers should be installed in
formation concerning the installation of covers such a manner that free drainage is assured. Care
340
should be taken not to create an area which will noticeable, but important, is the respiratory
trap and hold salt water. Covers may also act as irritation which may be caused .
a green house in warm weather and cause The two most important hazards of jet engine
collection and condensation of moisture under exhaust are the high temperature and high
neath . Covers should be loosened or removed velocity of the exhaust gases from the tailpipe.
and the aircraft ventilated on warm sunny days. High temperatures will be found up to several
hundred feet from the tailpipe, depending on
wind conditions. Closer to the aircraft, these
FLIGHT LINE SAFETY temperatures are high enough to deteriorate
PRECAUTIONS bituminous pavement .
Quite frequently when a jet engine is being
In addition to the more specific safety started , excess fuel accumulates in the tailpipe;
precautions presented in various other chapters when the fuel ignites, long flames are blown out
and in other sections of this chapter, there are a of the tailpipe. The possibilities of this hazard
number of miscellaneous precautions which should be known by flight line personnel and all
must be observed when working on the aircraft flammable materials should be kept clear of the
flight line. The following are especially impor danger area .
tant.
During maximum power settings, the high
velocity of the exhaust gases may pick up and
Intake Duct Hazards blow loose dirt, sizable rocks , sand , and debris
several hundred feet . Therefore, due caution
When working with reciprocating engine should be used in parking an aircraft for runup .
aircraft, the propeller represents the greatest The General Information section of the
single hazard to personal safety ; however, the jet applicable Maintenance Instructions Manual
engine presents several major hazards. The air contains information concerning the exhaust
intake duct of operating jet engines represents hazards. These instructions should be
an everpresent hazard to both personnel working strictly adhered to. NO ONE should foolishly
near the inlet duct of the aircraft and to the experiment with the safety margins specified.
engine itself if the turnup area around the front After engine operation , no work should be
of the aircraft is not kept clear of debris. This done to the exhaust section for at least one-half
hazard is, of course, greatest during maximum hour ( preferably longer ). If work is necessary
power settings. immediately, asbestos gloves must be worn.
The air inlet duct may develop enough
suction to pull hats, eyeglasses, loose clothing, Engine Noise
and rags from pockets. All loose articles should
be made secure or removed before working Modern jet engines produce noise capable of
around the engine. In some engines the suction causing temporary as well as permanent loss of
is strong enough to pull a man up to , or partially high frequency hearing. The proper precautions
into the inlet . Needless to say , precautions must
> are as follows:
be taken to keep clear of the inlet.
Protective screens are supplied as part of the 1. Wear the proper ear protection (earplugs
ground handling equipment for most jet aircraft. and /or sound attenuators).
These screens should be installed prior to all 2. Do not exceed the time limits on exposure
maintenance turnups . to the various sound intensities.
3. Have periodic checks on hearing ability.
Exhaust Area Hazards
Engine noise is broadcast from the aircraft in
Jet engine exhaust creates several hazards. patterns which vary in direction, distance, and
Tests show that the carbon monoxide content of intensity with engine speed . Generally, the most
jet exhaust is low ; however, other gases are intense sound areas are in the shape of two lobes
present which are irritating to the eyes. Less extending out and aft from the aircraft
341
centerline. However, dangerous intensities are Seat Ejection Mechanisms

also present to the side and forward of the
aircraft . All safetyprecautions must be strictly
Damage to hearing occurs when the ear is observed when working around aircraft
exposed to high sound intensities for excessive equipped with an ejection seat . These safety
periods. The higher the sound intensities, the precautions cannot be overemphasized , as
shorter is the period of exposure which will accidental actuation of the firing mechanism can
produce damage . Above 140 db sound intensity, result in death or serious injury to anyone in the
any exposure without ear protection can cause cockpit area.
damage. Each ejection seat has several ground safety
NOTE : Sound intensity is measured in pins, the exact number depending upon the type
decibels (db) . A decibel is a number which of seat . These safety pins are provided on
relates a given sound intensity to the smallest redflagged lanyards for use at every point of
intensity that the average person can hear. potential danger. They must be installed
The wearing of regulation ear protection . whenever the aircraft is on the ground or deck ,
(earplugs and/or sound attenuators) will raise and must never be removed until the aircraft is
the limits of time exposure . All personnel ready for flight.
working within danger areas should be familiar The following general precautions should
with calculated db levels (as specified in the always be kept in mind :
applicable Maintenance Instructions Manual)
and should wear the necessary protective 1. Ejection seats must be treated with the
equipment . same respect as a loaded gun .
2. Always consider an ejection seat system
loaded and armed.
Movable Surface Hazards 3. Before entering a cockpit , know where the
ejection seat safety pins are and be certain of
Movable surfaces such as flight control their installation .
surfaces, speed brakes, power operated canopies, 4. Only authorized personnel may work on
and landing gear doors constitute a major hazard ejection seats and components and only in an
to flight line personnel. These units are normally authorized area .
operated during ground operations and main
tenance. Therefore, care should be taken to Overheated Wheel Brakes
insure that all personnel and equipment are clear
of the area before operating any movable In the event an aircraft has been subjected to
surface . excessive braking, the wheels may be heated to
the point where there is danger of a blowout or
Power operated canopies have safety locks fire . NOTE : Excessive brake heating weakens
which must be installed during ground handling tire and wheel structure , increases tire pressure,
operations. These safety locks prevent the and creates the possibility of fire in the
accidental closing of the canopy and this magnesium wheel . When the brakes on an
eliminates the possibility of personnel being aircraft have been used excessively , the fire
crushed as the canopy closes. department should be notified immediately and
Information
The General Information and Servicing all unnecessary personnel should be advised to
section of each Maintenance Instructions Manual leave the immediate area .
contains specific information concerning the If blowout screens such as the one shown in
various movable surface hazards and specifies figure 12-8 are available, they should be placed
the safety locks which must be used. Personnel around both main wheels. These screens help to
involved with line operations and maintenance eliminate the possibility of damage or injury in
should pay particular attention to this informa the event of a blowout .
tion since some of these units move extremely Upon sudden cooling, an overheated wheel
fast and with terrific power . may fracture of fly apart , which would hurl RE
342
IVS
DANGER AREA
DANGER AREA
HOT WHEEL
AM.200
Figure 12-8 . -Use of blowout screen on overheated brakes.
bolts or fragments through the air with board to puncture the tires and release their
sufficient speed to injure personnel. If the tire is pressure . (See fig. 12-9. )
flat, explosive failure of the wheel or tire will The recommended procedure for cooling
not result . overheated wheel, brake, and tire assemblies is
Required personnel should approach over to park the aircraft in an isolated location . Then
heated wheels with extreme caution in the fore allow the assembly to cool in ambient air. The
or aft directions - never in line with the axle. use of cooling agents to accelerate cooling is not
CAUTION : The area on both sides of the tire recommended unless operational necessity
and wheel , in line with the axle , is where the dictates their use. The application of the agents
fragments would be hurled if the tire were to exposes personnel to danger by requiring their
explode and is therefore called the danger area presence near the overheated assembly . How
( fig . 12-8 ) . ever , if it is necessary to accelerate cooling, a
Heat transfer to the wheel will continue for straight stream of water or fog is recommended.
some period of time until the brake is cooled . The water should be applied in 10- to 15
Therefore, the danger of explosive failure may second periodic bursts, not in a continuous
exist after the aircraft is secured if action is not discharge. Each application should be separated
taken to cool the overheated brake. by a waiting period of at least 30 to 60 seconds.
NOTE : When a wheel/brake assembly over A minimum of 3 to 5 applications is usually
heats , making rapid deflation of aircraft tires necessary .
necessary to prevent a wheel assembly When fog is used, the fog is deflected to the
explosion , ground personnel should direct the brake side of the wheel for a period of 5 to 10
pilot to taxi the aircraft over a tire blowout seconds . Each application should be separated
343
00
MATERIALS LIST
1/4 x 12 x 20 STEEL PLATES ( 2 REQ )
1/2 x 20 STEEL STUDS ( 34 REQ )
2" 2 " 1/2 x 20 JAM NUTS ( 34 REQ )
2x6x20 WOOD BOARDS ( 2 REQ )
5"
1/2" STUD
2" 12 " GROUND TO POINT
JAM NUT
1 | 2"
3" 3
. MANILA STRAP
-20 "
AAAAAAAAAAAAAAAAA 1-1/2"
WOOD GUARD
DAVE
g g g осc
c
оc
g g g с
c
Ag g
( END VIEW)
R
AM. 1226
Figure 12-9 . - Emergency tire deflator. .
by a waiting period of at least 20 seconds. This Once the brake has been properly cooled , at
method is applied as long as it is necessary to permit the wheel to cool in ambient air. A
je
control the temperature of the affected crosswind or forced air from aa blower or fan will de
assembly. Never use CO2 for cooling. assist in cooling the wheel. in
344
Chapter 12-LINE OPERATIONS AND MAINTENANCE
The aircraft should not be moved for at least attenuators , flight deck shoes, flotation gear,
15 minutes following cooling operations. and an adequately secured whistle and survival
light.
Any maintenance performed on aircraft
FLIGHT DECK SAFETY which will require wingspread / fold , respot,
PRECAUTIONS turnup , blade track , jacking, etc. , or main
tenance that will prevent the aircraft from being
The flight deck of an aircraft carrier is one of moved regardless of how much or how little
the most hazardous places in the world and one time is required for the work to be performed
of the busiest during launching, recovery , and must take into consideration the fact that
respotting of aircraft. Plane captains and other approval to proceed with such maintenance
maintenance personnel assigned specific duties actions must be approved through the activity's
associated with the flight deck must be Maintenance Control. The activity's Main
constantly aware of this dangerous environment. tenance Control, before it can grant approval,
The predeployment training lectures for such must have obtained permission from the Aircraft
personnel should include shipboard handling Handling Officer via the Air Wing /Group
procedures, flight and hangar deck safety Maintenance Liaison Officer or his representa
precautions, responsibilities during launch and tive .
recovery of aircraft, tiedown requirements and When participating in aircraft turnup or
techniques, and special shipboard maintenance jacking operations make sure that the permission
procedures and safety precautions. This training of the Aircraft Handling Officer has been
requirement is in addition to the general received as previously stated and that all ship's
indoctrination given all personnel concerning regulations are observed . Safety men with
flight quarters, general quarters, fire, abandon sufficient line to block off the area must be
ship , man overboard , and other general drills; stationed around the aircraft .
ship conditions, smoking and safety precautions Each ship may have safety precautions unique
and watch standing requirements peculiar to to that ship due to special circumstances and
shipboard operations. operational requirements. Petty officers are
The previously discussed flight line safety charged with the responsibility of knowing and
precautions are applicable to flight deck enforcing those that apply to their area of work
operations. The primary difference is that and their men.
because of the limited space and tempo of
operations experienced on the flight deck the
situation is increasingly more dangerous. ARMED AIRCRAFT PRECAUTIONS
During launching and recovery of aircraft all
personnel not required by such operations Maintenance personnel must remain alert to
should leave the flight deck and catwalk areas. the potential danger of the weapons utilized on
The safe parking area aft of the island is an the various types of aircraft. Shore stations
unauthorized space for personnel during aircraft utilize a specified area for arming and dearming
recovery . Personnel should not stand in or aircraft. Aircraft returning from flights with
otherwise block entrances to the island structure hung weapons are required to be dearmed (by
or exits leading off the catwalks. Never turn qualified Aviation Ordancemen ) in the landing
your back on aircraft taxiing on the flight deck. area or just clear of the landing area . If forward
Be alert for the unexpected at all times. There is firing weapons are involved the aircraft must be
no room for carelessness, daydreaming , or stopped with a clear area ahead of the aircraft
skylarking on the flight deck at any time. and dearmed prior to taxiing into designated
All personnel assigned flight quarters on or recovery spots. All aircraft landing with
above the hangar deck must wear appropriate unexpended weapons should be dearmed as soon
jerseys and helmets. Personnel on the flight deck as possible in ALL cases prior to commencement
during flight quarters must wear the cranial of any postflight checks, servicing, or refueling
impact helmet or its equivalent, goggles, sound of the aircraft.
345
PREVENTION OF FOREIGN OBJECT available . The need for the services of the fire
DAMAGE TO JET ENGINES crews can , in most cases, be avoided by the
prompt and efficient use of firefighting equip
Foreign object damage is an ever-present ment which is available at all times on the flight
hazard to the operation of jet engines. It is the line. It is of the utmost importance that every
responsibility of all aircraft maintenance person man working on the line be familiar with the
nel to conscientiously adhere to and follow location and use of the firefighting equipment.
preventive procedures and policies to eliminate CO2 bottles are the most common fire
ingestion of foreign objects by jet engines. extinguishers used on the line. These bottles
Several areas of concern are parking and storage contain a sufficient quantity of CO2 to handle
areas and procedures, engine installation , and most small fires started on the flight line . An
engine ground operation. Frequent and periodic aircraft should never be fueled , defueled , or its
inspection of engine nacelles, inlet ducts, and engines started without having one or more men
storage areas is recommended. When required, standing by with CO2 bottles.
careful cleaning of these areas should be Some aircraft carry one or more small CO2
accomplished . All maintenance personnel must bottles. These bottles are intended for use in
exercise extreme care while performing main flight and should never be used in ground
tenance procedures in and around the aircraft to operations except in extreme emergency . In the
prevent foreign object damage to the engines. event that they are used , they should be
The greater size of the newer jet engines creates replaced prior to the aircraft's next flight.
greater suction pressures and larger suction Whenever an engine is started , personnel with
areas. The higher suction pressures enable the adequate fire extinguishers must always be
engines to pull objects from greater distances maintained in the immediate vicinity of the
into the engines compressor section . Objects engine. When available, a 15-pound CO2 fire
may be picked up from the deck areas or from extinguisher is the minimum which should be
some areas within the aircraft which are directly used when starting an engine.
or indirectly open to the engine bay or intake
duct . Therefore, it is mandatory that personnel
performing maintenance in and around the Firefighting Procedure
aircraft account for all tools, hardware, and
components after all maintenance procedures If a fire starts in the tailpipe of a turbojet
and operations. engine as it is being started , the engine should be
The turnup and taxi area of the jet engine given a dry start ; that is , a start (motoring of the
must be cleaned frequently to insure that the engine) with the switches which control the fuel
area is free of such foreign objects as nuts , bolts, in the OFF and CLOSED position .
washers, tools, cotter pins, safety wire, stones, If the fire persists, CO2 can be discharged into
rags, etc. Numerous jet engines have been the inlet duct so that it can be drawn through
completely demolished because someone failed the engine while it is being given the dry run .
to police the turnup and taxi area for loose gear CO2 should not be discharged directly into the
before the engine was started . engine exhausts as this may damage the engine.
Anyone working in the vicinity of jet aircraft In case the fire is on the ground under the
should insure that all personal effects such as engine overboard drain , the CO2 should be
hats, gloves, pens, and cigarette lighters are discharged on the ground rather than on the
secured. These items may also cause foreign engine. This holds true also if the fire is at the
object damage . tailpipe and the fuel is dripping to the ground
and burning.
EXTINGUISHING FIRES The methods described here are for
DURING GROUND TURNUP gency use only , because the fire department
should always be notified when there is a fire in
At air stations or aboard a carrier, ex peri or near an aircraft. If the fire cannot be
enced crash crews and fire crews are readily extinguished with the equipment at the scene,
346
secure all switches, abandon the aircraft and standardized between two or more countries . No
stand by to assist the fire department upon their product is allocated more than one NATO
arrival. symbol , and a number once assigned is never
used for any other product . The NATO symbol
AIRCRAFT SERVICING is clearly distinguishable from all other
markings; for example F -22 will be used by all
Servicing of aircraft includes replenishing of NATO countries to identify 115/145 aviation
the fuel, oil, hydraulic fluid , and other gasoline.
consumable materials. Also included under this
heading are checking the tires for proper Refueling Safety Precautions
inflation, struts for proper extension , and the
various air storage units for proper pressure . Aviation gasoline is a highly volatile liquid
NOTE : All aircraft servicing should be which gives off a vapor . This aircraft fuel vapor
performed in accordance with the applicable set is heavier than air and will settle to the ground ,
of Maintenance Requirement Cards . The set of accumulating in dangerous amounts in depres
cards covering the daily inspection contains the sions, troughs, or pits ; and when combined with
servicing instructions for each system . Further air in the proper proportions, forms an explosive
instructions concerning servicing may be found mixture .
in the applicable Maintenance Instructions The ignition of vapor from aircraft fuel may
Manual . occur from static sparks, sparks from tools , hot
exhaust pipes, lighted cigarettes, electrical
FUEL REPLENISHMENT devices, and similar sources. A violent explosion
followed by fire will result if liquid gasoline is
Identification of Aircraft Fuels present.
On the other hand, fuels such as JP-4 have
Aircraft engine fuels currently in use are some of the same characteristics of gasoline, but
classified into types and grades as follows: by no means the same substance. Different
characteristics such as lower vapor pressure and
1. Reciprocating engine fuels; i.e. , AVGAS high aromatic content exist in this fuel;
( aviation gasoline ). therefore, special precautions in its handling
must be taken .
NATO All existing fire precautions must be adhered
GRADE SYMBOL COLOR to during the fueling process. Smoking is not
permitted in the aircraft during fueling. Also , no
80/87 F- 12 Red smoking or naked lights (such as are produced
91/96 F - 15 Blue by oil lanterns, candles, matches, exposed
100/130 F - 18 Green electric switches, sliprings or commutators , a
115/145 F -22 Purple dynamo or motor, any spark -producing
electrical equipment , or any burning material)
2. Turbine engine fuels; i.e. , JP ( jet fuel). are permitted within 100 feet of an aircraft
NATO being refueled , or of fuel storage tanks. No lights
GRADE SYMBOL DESCRIPTION
other than approved explosion-proof lights are
permitted within 50 feet of these operations,
JP - 4 F -40 Low vapor pres
and no light of any sort may be placed where it
may come in contact with spilled fuel. Warning
sure type .
signs should be posted as a precautionary
measure .
JP - S F -44 High flashpoint
kerosene type . All accidental spillage of aircraft fuels or
other combustible liquids must be immediately
The NATO symbol is a code number assigned removed by washing, covered with a foam
to a product after it has been classified as blanket to prevent ignition , or neutralized by
347
other means. The proper fire authorities must be creates a dangerous fire hazard , and painful
notified any time a large amount of aviation fuel blisters may be caused by direct contact with
is spilled . fuel in the same manner as fire burns. When fuel
Aircraft fuel tanks must be filled , purged , or has entered the eyes , medical attention should
have an inert gas (such as CO2) over the gas in be obtained immediately .
the tanks before storing aircraft in hangars, since When an aircraft is to be fueled by a truck, it
this leaves no space for explosive vapors to form . should not be located in the vicinity of possible
Nonspark tools must be used when working sources of ignition such as grinding, drilling, or
on any part of a system or unit designed for welding operations. When practicable , a
storing or handling combustible liquids. minimum of 50 feet from other aircraft or
The use of leaky tanks or fuel lines is not structures and 75 feet from any operating radar
permitted. Repairs must be made on discovery, set should be maintained . Consideration must be
with due regard to the hazard involved . given to the direction of the wind so that fuel
Gasoline must be strained if there is the vapors will not be carried toward a source of
slightest chance that water may be present in the ignition .
fuel. Most fueling trucks and underground The tank truck should be driven to a point as
storage systems have filter/separators which distant from the aircraft as the length of the
automatically filter water out of the gasoline hose permits, and preferably to the windward
>
before delivering it to the aircraft tank . These ( upwind ) side of the aircraft. It must be parked
ilter/separators should be checked daily for dirt parallel to or heading away from the wing, or in
and water. This system serves the same purpose such a position that it may be driven away
as the sediment bulb or tank in an automobile quickly in the event of fire. As soon as the
gasoline system . fueling operation has been completed, the truck
Aircraft should be fueled in a safe place. Do should be removed from the aircraft's vicinity.
not fuel or defuel an aircraft in a hangar or other The truck manway covers should be kept closed,
enclosed space except in case of emergency . except when a tank is actually being loaded , or
Aircraft should be free from fire hazards, have when pumping fuel at 25° F or below, because at
engine switches off, and chocks placed under the such temperatures vent valves may be inoperative.
wheels prior to fueling or defueling. NOTE : The operation of fuel trucks at many
As an AMS striker, one of your duties might air stations is performed by civilian crews . Even
pe standing by with aa CO2 fire extinguisher or though the Aviation Structural Mechanic S may
other firefighting equipment while the aircraft is not be called on to operate or drive fuel trucks,
being refueled . The AMS striker assigned to he must be thoroughly familiar with the entire
tand by the fire extinguisher should insure that procedure to insure safety of the fueling
he extinguisher is full (by inspecting for the operation , in which · he will be involved
ead seat on the release mechanism ) and that he frequently.
s familiar with the release mechanism on the Refueling crews usually include a minimum of
ype extinguisher in use. When fighting a fuel three men . One person stands by with the
fire it is most important that action be taken firefighting equipment ; another stays with the
mmediately ; therefore, the fire watch should be truck ; and the third man handles the fuel hose at
lert at all times . the aircraft and fills the tanks. A member of the
CAUTION : Guard against breathing hydro crew makes sure that both the aircraft and the
carbon (fuel) vapors as they may cause sickness truck are properly grounded to prevent sparks
or may even be fatal. Do not let fumes from static electricity. A check should be made
accumulate -use adequate ventilating measures. to see that all radio equipment and unnecessary
Also , avoid getting fuel on clothes, skin , or in electrical switches are turned off. Outside
the eyes , because of the high lead content. electrical power should not be connected to the
Fuel-saturated clothing should be removed as aircraft unless it is necessary to operate the
soon as possible , and the parts of the body equipment involved with refueling. Care should
exposed to fuel washed thoroughly with soap be taken to identify the aviation fuel before
and water. Wearing clothing saturated with fuel beginning the refueling operation. Refueling
348
trucks have the type fuel contained in the tanks The nozzle should always be grounded prior
painted across the side of the tank in black to being placed in the filler neck in order to
letters. An AMS who is involved with servicing prevent sparks caused by static electricity . The
aircraft should become familiar with the various nozzle should be supported while in the filler
grades of fuel and the aircraft's fuel require ck to prevent damage to the filler neck and in
ments in order to insure that the appropriate the case of aircraft which use bladder type fuel
fuel is always used . cells (cells made from a type of rubberized
nylon cloth ) to prevent the possibility of
Gravity Fueling damaging the cell with the end of the nozzle.
Many naval aircraft are refueled by the gravity Pressure Fueling

fueling system . (See fig. 12-10) Some aircraft
may be refueled by either the gravity or pressure Most of the newer naval aircraft are refueled
fueling system and other aircraft are fueled from by the pressure fueling system . This system is
a single point by the pressure fueling system . employed to enable faster “operational turn
Gravity fueling is accomplished by grounding around ” of the aircraft.
the nozzle , inserting the nozzle in the cell filler Pressure fueling is usually accomplished from
neck , and filling the tank to the bottom of the
> a single point . Fuel from this point is supplied to
filler port neck . the various wing and fuselage tanks. In some
GROUNDING JACK
GRAVITY
FUELING
NOZZLE
GROUNDING
RECEPTACLE
G TA
WINTURN NK
SCREW
COMPLETELY
OM CAOS
FUEL
57J GALS
FILLER CAP
AM.201
Figure 12-10 . -Gravity fueling.
349
PRESSURE FUELING
AND DEFUELING
FUGLING
ON CHECK ADAPTER VALVE
SWITCH
DROP ON
TANK OFF
FUELING PRIMARY SECONDARY
OFF OF
‫פומפו‬
SWITCH PANEL
0
MESSURE FUELING AND
DEFUELING NOZZLE o
GROUND
VIRE
MANUAL FLOW AND
NO -FLOW VALVE ne
in
ME
o
PIE
aut
λοι
pre
diff
app:
shot
fuelf
1
safet
press
side
2.
NOUT
aircr
मुंग 3.
and
the fL
upper
nozzl
keys a
the lif
proper
AM. 202 the air
Figure 12-11. - Pressure fueling.
5.
accor
Instru
cases, the drop tanks and flight refueling standard on all aircraft which use the pressure are ass
package may also be refueled from this point. fueling method. The electrical panel and insure
The pressure fueling station on the aircraft is controls differ from one aircraft to another, proper
equipped with a pressure fueling and defueling depending upon the complexity of the fuel there
receptacle and an electrical control panel. (See 1
system . The more complex systems may require even ca
fig. 12-11 . ) The pressure fueling receptacle is several switches and lights. The General
6. W
350
Information and Servicing section of the opening handle is free to turn whenever fueling
applicable Maintenance Instructions Manual is to be started . To start fueling turn the handle
contains illustrations and instructions concern to the FULL OPEN position . Rotating the
ing the pressure fueling system . opening handle more than 180 degrees opens the
The pressure nozzle shown in figure 12-11 is poppet valve in the nozzle and locks it in the
permanently attached to the refueler hose. The OPEN position. Position the appropriate switch
pressure nozzle is equipped with a ground wire on the fuel panel to the FUEL position . The fuel
which is used to drain off any static electricity should shut off automatically when the cells are
that may have built up in the nozzle . However, full.
once the nozzle is attached to the aircraft, it acts CAUTION : During pressure fueling the fuel
on its own ground. system should be inspected carefully for leakage.
As the connection is made , the pressure If any leaks are apparent, fueling should be
nozzle opens a spring-loaded valve within the stopped and corrective action should be taken.
inlet to the fuel tanks. Once the connection is 7. When fueling is complete , the pressure
made , there is no further need for grounding the fueling nozzle is removed by rotating the lifting
other cells or tanks. Aircraft which employ the handles counterclockwise until the nozzle is
pressure fueling system are equipped with unlocked from the fueling receptacle. The dust
automatic equipment for shutting off the fuel cover should be pulled up over the nozzle face
flow when the tanks are full. immediately and the safety cap replaced on the
The following is a general procedure for aircraft receptacle .
pressure fueling an aircraft. Since the controls Every safety precaution must be taken to
differ from one aircraft to another the insure that no dirt or foreign matter enters the
applicable Maintenance Instructions Manual nozzle and that the nozzle nose is completely
should always be checked prior to pressure clean before it is connected to the aircraft. The
fueling an aircraft. dust cover must be kept on the nozzle at all
1. Remove the pressure fueling receptacle times except when actually fueling an aircraft.
safety cap by turning counterclockwise. Pull the The pressure fueling nozzle can be damaged
pressure fueling nozzle dust cover up and to one by careless handling. Guard against dropping the
side of the outer shell . nozzle or allowing it to swing heavily against
2. Ground the nozzle by inserting the structures or equipment during handling. Never
grounding plug into its receptacle on the drag the nozzle on the deck .
aircraft. Never force the operating action of the
3. Lift the nozzle by its handles into position nozzle . If the unit does not couple freely or
and engage the lower slot over the lower lug on open or close readily, locate and correct the
the fueling receptacle . Tip the nozzle so that the misalignment or mechanical jam.
upper slots engage the upper lugs . Press the
nozzle in firmly so that all three nozzle lock Defueling
keys are depressed . Lock the nozzle by rotating
the lifting handles clockwise . Defueling may be necessary for a variety of
4. Set the refueling panel switches in the reasons such as fuel cell repairs, removal of
proper position and apply electrical power to external fuel tanks , failure of fuel system
the aircraft. components, and changing of fuel loads.
5. Position the vent monitors as necessary in Aircraft which utilize pressure fueling are
accordance with the applicable Maintenance normally defueled from the pressure fueling
Instructions Manual . NOTE : The vent monitors adapter which allows the entire system to be
are assigned to the various fuel system vents to defueled from a single point. Some older aircraft
insure that the aircraft's fuel cells are venting are equipped with one or more defueling valves.
properly. Should the cells not vent properly , Some residual fuel will generally be left in the
there is a possibility of rupturing the cell and bottom of fuel cells following defueling.
even causing major structural damage . Residual fuel can usually be emptied or drained
6. With the nozzle locked in place , the through the fuel cell water drain valves, using a
351
special draining adapter and appropriate while others are lubricated entirely with a dry
container to catch the fuel. When defueling sump type. Wet sump engines store the
external fuel tanks , it may be necessary to insert lubricating oil in the engine proper like
the defueler hose in the filler port. automobile engines, while dry sump engines
Defueling will normally be accomplished utilize an external tank mounted on or near the
outside thehangar and under controlled engine. Oil in jet engines serves the two - fold
conditions as specified in the General Informa purpose of lubricating and cooling.
tion and Servicing volume of the applicable Servicing of the engine oil system is usually a
Maintenance Instructions Manual . If it is
simple task of checking the tank for the proper
absolutely necessary to defuel an aircraft in the oil level and bringing the oil level up to the
hangar, doors should be open to provide required amount. On aircraft with a dry sump
ventilation through the hangar and all shop system , servicing may consist of pumping
doors leading into the hangar should be closed . uncontaminated oil directly into the supply
No work should be accomplished on or around tank . However, on some aircraft the tank is
the aircraft during the defueling operation and located in an inaccessible compartment, and a
all sources of ignition should be prohibited in pressure tank is required to fill the oil tank .
the area . The safety precautions defined in Figure 12-12 provides an example of the
NavMat P 5100 , the applicable MIM , and local
> pressure oiler, the engine oil pressure fill station
directives should be strictly adhered to at all located in the engine nacelle, and the penlight
times . (PON 5-75) used in servicing the engines on E -2A
and C-2A aircraft. Servicing consists of the
OIL REPLENISHMENT following steps:
1. Set the penlight switch to ON , with the
Identification of cap in place . The bulb should light.
Aircraft Engine Oils 2. Remove the cap and insert the plug into
the OIL TANK FULL test jack at the fill
Aircraft engine oils are identified by their station). The bulb should go on . If the bulb does
military specification number and/or 4-digit not light, oil level is low and servicing is
numbers; for example, 1065. The 4 -digit required .
numbering system identifies the intended use of 3. Remove the penlight from the oil tank fill
the oil and its viscosity . The first digit designates test jack and with the switch still ON insert into
the intended use, lxxx series being for aircraft the DRAIN PLUG CHECK jack . If the bull
engine lubrication . The last three digits indicate lights it is an indication of an accumulation o
the viscosity ; for example, 1065 oil has a metallic material on either or both engin
viscosity rating of 65 , 1080 oil has a viscosity magnetic chip detectors. Call such indications to
rating of 80, etc. Viscosity is defined as the the attention of the appropriate supervisor
internal fluid resistance to flow caused by personnel. If the bulb remains out proceed wit
molecular attraction . servicing.
NOTE : Both the Navy and the Air Force use 4. Reinsert the penlight into the OIL TAN
the Saybolt Scale for determining viscosity. FULL test jack.
Saybolt viscosity numbers should not be 5. Insure that the pressure oiler is properl
confused with SAE numbers. filled . Prime the supply line, reset the quantit
The synthetic oils used in most turbojet meter to zero , and connect the oiler filler line
engines are referred to by their military the pressure fitting and the overflow line to th
specification number ; for example , MIL return fitting at the fill station .
L-23699 . 6. Pump oil into the system until the penlig
bulb lights and note the quantity on t .
Servicing Engine Oil Tanks quantity meter. If oil consumption excee
limits, notify the appropriate maintenance chi
Some aircraft engines utilize a combination 7. If oil consumption is within limi
dry and wet sump type of lubricating system continue pumping oil at a slower rate until
352
QUANTITY PRESSURE
METER GAGE
HAND
FILLER PUMP
LINE 3
OVERFLOW
LINE
PRESSURE OILER
OIL TANK FULL TEST JACK DRAIN PLUG CHECK JACK
FILL
STATION
RETKU PRESSYKE
RETURN
FITTING PRESSURE
FIT TING
OVERFLOW
LINE
BULB
FiSWITCH
Inh
PLUG
మరియు
FILLER
LINE
FITTING
CAPS
CAP
PENLIGHT PON5 - 75
AM ,1211
Figure 12-12 . -Oil System servicing equipment ( E -2A / C - 2A ).
flow is observed at the overflow discharge in the complished within a specified time limit after
pressure oiler. engine shutdown. In most cases if the engine is
NOTE : Checking and filling of the engine oil not serviced within these time limits, the oil
system of most jet engines must be ac system must be drained and refilled to insure a
353
proper quantity of oil or the aircraft could be naval aircraft. Use only the specified oil
turned up to scavenge oil from the engine gear indicated in the General Information and
case to the oil tank . In all cases follow the Servicing volume of the MIM for the particular
servicing instructions provided in the ap aircraft being serviced . Improper lubrication can
propriate Maintenance Instructions Manual . cause internal damage and disastrous failure. To
If unusually high oil consumption is noted , allow for normal expansion and some foaming
maintain an accurate record of consumption as of the oil under use, do not overfill the oil tank.
specified by the applicable inspection require NOTE : The synthetic oil used in some aircraft
ments or the MIM . Oil consumption can be a engines and CSD assemblies is harmful to human
reliable indicator of impending engine malfunc skin and respiratory tract , and has a deterio
tion and a determining factor in deciding rating effect on rubber and painted surfaces.
whether an engine is acceptable for flight status . Handle in such a manner as to prevent skin
CAUTION : Do not overfill engine oil systems. contact and/or damage to the aircraft finishes.
The system previously discussed requires filling The presence of contamination in the
to overflow , however, some aircraft oil systems lubricating system of aircraft engines and CSD
require that adequate space be allowed for units can be as disastrous to their operation as
normal foaming of the oil and expansion when the presence of contamination in oxygen ,
the engine is operating. hydraulic, and fuel systems. Proper handling of
lubricants and servicing equipment and strict
Servicing Constant Speed conformance to servicing instructions provided du
Drive Assemblies in the MIM will minimize the possibility of
introducing external contamination . Any
Several late model reciprocating and jet suspected contamination should be immediately the
engine aircraft utilize a constant speed drive called to the attention of the appropriate wi
(CSD) assembly to maintain the aircraft's maintenance supervisor. ab
generator( s) at a constant speed . The assembly ins
transfers and converts variable speed rotation of HYDRAULIC FLUID REPLENISHMENT in
the aircraft engine into a constant speed rotation fill
necessary to drive the generator at a constant Identification of the
speed which will meet all the aircraft's electrical Hydraulic Fluid me.
demands . oth
At least one aircraft features a combination Aircraft hydraulic fluids are identified by H
constant speed drive/ starter (CSD/S) which their military specification number . Hydraulic app
provides both pneumatic starting for the engines fluid , MIL-H-5606C, is now being used in the Fige
and constant speed drive for the generator. This hydraulic systems of all naval aircraft. This fluid som
CSD/S can be operated in engine starter, is also used in the shock struts, shimmy CON
constant speed drive , or air turbine motor modes dampers, and brake systems of all aircraft. quic
of operation. MIL-H-5606C hydraulic fluid is colored red and fili
Proper operation of any CSD assembly is is available in 1 -quart, 1 -gallon, 5 - gallon, and press
extremely dependent on proper servicing by 55 -gallon containers. syst
personnel assigned to line maintenance . In most NOTE : Hydraulic fluid MIL-H-6083C is a a sis
cases the CSD or CSD/S must be serviced within preservative type hydraulic fluid used in the filli
a specified period after engine shutdown to preservation of hydraulic systems and com A
obtain an accurate oil level reading. If this time ponents . While it is red in color and generally sho
is exceeded the oil reservoir must be drained considered compatible with MIL-H-5606C port
prior to servicing with the required volume of hydraulic fluid , it should NOT be used to service the 5
specified lubricating oil or the aircraft turned up aircraft hydraulic systems. to
so that the oil level can be checked within the d
bydra
designated time limit. Servicing Hydraulic Systems the
Several types of lubricating oils are utilized in whic
the various types of CSD assemblies found in Older type aircraft hydraulic systems are into
354
serviced by checking the fluid level (on a sight fluid to open air or other atmospheric
gage which is usually located on the side of the contamination . In addition, waste of hydraulic
reservoir ) and filling to the prescribed level. fluid is reduced since a partially used can of
Before adding fluid to this type reservoir, always fluid does not have to be thrown away but can
check the reservoir instruction plate for proper be retained in its contamination -free condition,
filling instructions. The instructions plate will be in the unit, until it is needed and used on
attached either to the reservoir or to the aircraft another job .
structure near the filler opening of the reservoir. This type of servicing unit comes unpainted
The instruction plate contains the following and is to remain as such to eliminate the
information : possibility of paint chips getting into the aircraft
hydraulic system and contaminating them . All
Total capacity of the system. exposed parts of the unit have either been plated
Reservoir capacity . or are of hard anodized aluminum . The unit is
Refill level. also constructed so that it can stand on a
Specification and Color of fluid . 15-degree slope without turning or sliding and
Correct position of all actuating cylinders has a neoprene strip on its base to prevent
during filling. scratching or marring any surface on which it
rests .
Any other information considered necessary In addition , this unit provides exceedingly
during the filling of the reservoir. fine filtration through the use of 3 -micron filters
NOTE : After opening a can of hydraulic which remove minute particles that may be in
fluid, the entire contents should be poured into the fluid . With the use of this unit, the can of
the fill stand or servicing unit immediately. This fluid is sealed into the unit, and the fundamental
will eliminate the possibility of the fluid feature of preventing contamination from
absorbing dust and grit from the air. Current exposing the fluid to the atmosphere and other
instructions require that any remaining fluid left external contamination is accomplished .
in the hydraulic fluid container, after servicing a Most of the newer type aircraft have a visible
fill stand / servicing unit , be discarded and that means (usually sight gages) for checking fluid
the empty fluid container be destroyed im level ; however, some are equipped with lights
mediately and not used to store or handle any which indicate fluid level.
other fluid . Information concerning servicing of the
Hydraulic systems can only be serviced with hydraulic reservoirs of a particular type aircraft
approved 3-micron absolute filtered dispensers. is contained in the General Information and
Figure 12-13 shows a fill stand used to service Servicing volume of the applicable Maintenance
some aircraft hydraulic systems. The fill stand is Instructions Manual .
connected to the aircraft hydraulic system at a
quick disconnect which is provided for reservoir PNEUMATIC SERVICING
filling. The fill stand can be operated with air
pressure or using the handpump. Some aircraft Landing gear struts, hydraulic accumulators,
systems provide for filling several reservoirs from and various air storage bottles throughout most
a single point while others have provisions for naval aircraft must be serviced with compressed
filling each reservoir individually . air of nitrogen .
Another type of hydraulic servicing unit ,
shown in views A and B of figure 12-14, is a Pneumatic Servicing Equipment
portable hand -operated unit designed to accept
the standard 1 -gallon can of hydraulic fluid and The three main types of pneumatic servicing
to dispense it contamination free to aircraft equipment are the portable air bottle, the
hydraulic reservoirs. This is done by pumping nitrogen /air or nitrogen servicing trailer, and the
the hydraulic fluid from the original container, portable , high -pressure air compressor.
which functions as the unit's reservoir, directly
> PORTABLE NITROGEN/AIR BOTTLES.
into the aircraft's reservoir without exposing the The portable nitrogen / air bottle is a
355
AIR PRESSURE
REGULATOR
HYDRAULIC
PRESSURE GAGE
AIR PRESSURE
GAGE
SELECTOR
VALVES
HYDRAULIC PRESSURE HYDRAULIC PRESSURE

ADJUSTABLE RELIEF AND RETURN LINES
VALVE
. 2
2
ri
AIR PRESSURE
SHUTOFF VALVE
HAND PUMP
AIR PRESSURE
small
One
other
Tour
then
Ear
od
whic
nitro
kavica
porta
laken
not ex
AM . 204
AI
Figure 12-13 . - Hydraulic fill stand . TRAN
hown
356
VU
KL
A
‫مع‬
‫یہ‬
‫هم‬
‫ به‬۷
0.1
27-
9:
THEDIhes
(A ) ( B)
AM.902
Figure 12-14 . - Loe Hydraulic Servicing Unit, Model H250-1.
small high - pressure cylinder in a tubular steel naval air activities for servicing aircraft hydraulic
frame. It has a pressure regulator and two gages. and pneumatic systems. This trailer is designed
One gage indicates cylinder pressure and the to carry six air or nitrogen storage cylinders and
other indicates regulated pressure . A valve the necessary flow controlling mechanism . It has
mounted on the cylinder allows the user to shut a 30 -foot hose which is stowed in a box
the nitrogen / air off when the bottle is not in use . mounted between the top two bottles.
Each portable nitrogen /air bottle has recharge The air or nitrogen servicing trailer has a
and servicing instructions printed on a plate purifier (dehydrator) assembly. This purifier
which is attached to the frame. Only dry filtered assembly is essentially a reservoir which contains
air or nitrogen should be used in recharging a a chemical drying agent . This chemical drier is
nitrogen /air bottle which is to be used in provided to remove any moisture which may
servicing aircraft components. When recharging a have adhered to the valves or have been
portable nitrogen /air
/ bottle, care should be accidentally introduced into the system . The
taken to insure that the cylinder pressure does chemical is contained in a metal cartridge or can
not exceed that listed in the instructions. which is changed periodically . The gas passes
AIR OR NITROGEN SERVICING through the drier just before it enters the
TRAILER . - A servicing trailer similar to the one servicing hose .
shown in figure 12-15 will be found at most The bottles on the air or nitrogen servicing
357
HOSE BOX -GAS CYLINDERS

lo
MANIFOLD
PIE
CONTROL
VALVES WE
HANDBRAKE E
LEVER 100
the
int
BLEEDER Sy's
VALVES OL
UPPER bef
MANIFOLD
SHUTOFF disc
VALVES 200
PURIFIER
ope
I
str
trai
whe
REGULATORS E
CHASSIS LOWER
MANIFOLD ser
to
alo
DRAWBAR E
moc
Nay
LUNETTE EYE for
situ.
WHEEL ASSEMBLY con
con
MOO
plac
pro
sho
sho
mar
AM.207
Figure 12-15.-Air or nitrogen servicing trailer. on
Inst
CON
inst
trailer may be recharged using a high - pressure air or nitorgen servicing trailer, insure that the oft
compressor. cylinder pressure does not exceed the pressure
NOTE : When recharging the cylinders on the specified for the equipment being recharged. con
358
When operating the servicing trailer, the 5,000 psi . Handling of compressed air at
following precautions for safe operation should pressures up to 5,000 psi requires extreme
be observed . caution. The following servicing instructions will
Only a qualified operator should operate the help to insure a safe job :
trailer while charging a system or component. 1. Always use a remote control pressure gage
Complete familiarity with the trailer is a basic that is not defective and is properly calibrated .
prerequisite to safe operating techniques. NOTE : In accordance with current instruc
The servicing hose end and installation tions, all gages used in servicing aircraft
connection fitting should be thoroughly hydraulic and pneumatic systems must be
inspected prior to servicing and any particles of calibrated periodically to insure their accuracy.
foreign material removed . 2. Never use an uncontrollable source of
Never charge a system or component without high -pressure air . Always use a regulator in the
the proper fusible safety plug and blowout disc air system .
in the trailer charging system . 3. Always open the control valves slowly .
Always know the pressure existing in the Inflate the component slowly - 10 psi
system to be filled and the pressures in all the increments - until the recommended pressures
cylinders to be used up in the cascading process are reached.
before commencing charging operation . High -pressure air compressors like the air or
A malfunctioning pressure regulator should be nitrogen servicing trailer are equipped with one
disconnected from the line by closing its or more dehydrators. The cartridges used in
associated shutoff valve . The trailer can then be these dehydrators must be replaced periodically,
operated with the remaining regulator. depending upon the weather conditions. In
The charging hose must never be tightly damp , humid weather it will be necessary to
stretched to reach a connection . Position the replace the dehydrator cartridges more often
trailer so that the hose is not under tension then in dry , arid weather.
>
while servicing an aircraft.

After servicing an aircraft system , the Servicing Landing Gear Struts
servicing hose should be stowed in its container
to insure that it is not damaged by dragging For efficient operation of shock struts, the
along behind the trailer. proper fluid level and air or nitrogen pressure
AIR COMPRESSORS . - There are many must be maintained . In order to check the fluid
models of compressors in use throughout the level , the shock strut must be deflated and in the
Navy. Such a variety makes it difficult, at best fully compressed position . Deflating a strut can
for the average man to be master of all. The be a dangerous operation unless servicing
situation is further complicated by the variety of personnel are thoroughly familiar with the
configurations of dials and gages, regulator high -pressure air valve and observe all the
controls, hoses, and hose fittings on the same necessary safety precautions.
model compressor. The high -pressure air valve shown in figure
Most air compressors have an instructions 12-16 is used on all naval aircraft . This air valve
plate mounted on the control panel to aid in (referred to by its MS number, MS 28889-1 ) is
proper operation . These instructions plates used on struts, accumulators, and various other
should be kept in good condition , that is, they components which must be serviced with
should not be painted over or scratched and high -pressure air or nitrogen . The MS 28889-1
marred . If the instructions plate is not available high -pressure air valve has no valve core . Turning
on the compressor, the Operation and Service the 3 / 4 -inch swivel nut clockwise draws the
Instructions Manual for the particular air valve stem seat up into the valve body, thereby
compressor will contain all the necessary forming a metallic seal which traps the
instructions for the operation and maintenance high -pressure air or nitrogen in the component .
of the compressor . The following is a complete procedure for
Most of the newer high -pressure type air deflating a typical shock strut, servicing with
compressors will supply air pressure from 0 to hydraulic fluid , and reinflating.
>
359
on the shock strut instruction plate. Figure

12-17 illustrates the instruction plate found on
DUST
one type aircraft main landing gear strut. NOTE :
CAP The instruction plate may be found on the strut
or on the wheel door near the strut.
AIR
VALVE FILLING 7. Reinstall the air valve assembly , using a
STEM CHUCK new O -ring packing. The recommended torque is
SWIVEL
100 to 110 inch -pounds.
NUT 8. Lockwire the air valve assembly to the
strut, using the holes provided in the hex body
3/4 - INCH
- nut .
SWIVEL NUT 9. Inflate the strut, using a regulated high
-LOCKWIRE HOLE
pressuresource of dry air or nitrogen .
CAUTION : Under no circumstance should any
3 / 4 - INCH
PIN HEX SECTION type of bottle gas other than compressed air or
nitrogen be used to inflate shock struts .
" O " RINGS NOTE : On some shock struts the correct
VALVE
STEM
BODY THREADS amount of inflation is determined by measuring
SEAT the amount of extension (in inches) between
two given points on the strut and comparing this
figure with the amount of air in the strut. (See
AM.208
Figure 12-16 . -High -pressure air valve, type MS 28889 .
fig. 12-17 .) The proper procedure will always be
found on the instruction plate ( fig. 12-17). If the
instructions on the instruction plate are not
legible, reference should always be made to the
1. Position the aircraft so that the shock General Information and Servicing section of the
struts are in the normal ground operating applicable Maintenance Instructions Manual.
position . Make certain that personnel, work Shock struts should always be inflated slowly to
stands , and other obstacles are clear of the avoid excessive heating and overinflation .
aircraft .
10. Tighten the swivel hex nut . Recom
NOTE : Some aircraft must be placed on jacks mended torque is 50 to 70 inch -pounds.
for servicing the shock struts. 11 . Remove the high -pressure air line chuck
2. Remove the dust cap from the air valve . and install the valve cap. Tighten the valve cap emer
3. Release the air pressure in the strut by fingertight. emer

slowly turning the swivel nut counterclockwise. CAUTION : Do not remove the high -pressure So
CAUTION : When loosening the swivel nut , air line chuck before securing the swivel nut. DU)
make sure the 3 / 4 -inch hex body is either Since some aircraft struts require special bottle
lockwired in place or held tight with a wrench. servicing procedures , the General Information peur
If it is loosened before the air pressure has been and Servicing section of the applicable Main noun
released , serious injury may result . tenance Instructions Manual should always be
4. Make sure that the shock strut compresses checked prior to servicing the shock struts of The
as the air pressure is released . In some cases it any aircraft. icra
may be necessary to rock the aircraft after requir
deflating to insure complete compressing of the Openi
strut. Servicing Air Storage Bottles emerg
5. When the strut is fully compressed, the aircraf
valve assembly may be removed by cutting the Some aircraft use nitrogen /air storage bottles specif
safety wire and turning the 3 / 4 - inch hex body for the various emergency operations which are
nut counterclockwise . necessary for the safe operation of the aircraft Servic
6. Fill the strut to the level of the air valve and the safety of the crew. Air storage bottles The
opening, using the type hydraulic fluid specified are used for such functions as emergency brakes, has or
360
TRUNG
INFLATION INSTRUCTION STRUT EIT.
AEROL MD OY
REGARDLESS OF AIRCRAFT WEIGHT
ANO STRUT FRICTION , IF STRUT
DIM . Y
15 7/0
FULLY CIT .
2.91
150
DIMENSION "XIS MEASURED AND 301

THE CLEVELAND PNEUMATIC TOOL CO. PRESSURE GIVEN IN THE TAU TO 01/0 3.7
DIVISION OF CLEVELAND PNEUMATIC 406
INDUSTRIES INC , CLEVELAND , OHIO ,USA
THE LEFT, DOES NOT CORRESPOND $ 7/0
TO THAT IN STRUT, AIR SHOULD 63 423
FOR GRUMMAN AIRCRAFT ENGINEERING CORP .
IETNPAGE , LONG ISLAND ,NY,USA DE ADOED OR REMOVED AS 5 . 32
• 1/2 4.2
REQUIRED
Svo 462
ORDER NO . 5 1/4 403
SERIAL NO .
61/0 474
5 406
TYPE DESIGN NO . 4 7
010
4 50 52
SPECIFICATION NO. 4 1/2 630
43/0 653
TO CHECK FLUID LEVEL 960
I, NEMOVE VALVE CANOM NIGH PRESSURE AIR VALVE (M3 20000-1). 106
2. SLOWLY DISCHARGE ALL AIR OY TURCING SWIVEL NUTITURN COUN . 003
TEACLOCKWISC ) NOTC RATE OF DISCHANGE IS ESTAILISHED IY
AMOUNT SWIVEL NUT IS LOOSENEO . 3 7/1
3. ACMOVE COMPLETE AIR VALVE ASSEMILY AND FILL STRUT WITH 3 3/4
MILW- MOG ( RLO COLOR ) TO LEVEL OF FILLER MOLT VITM STAUT 36/0
IN NORMAL GROUND POSITION . GOS
1 1/2
RELACE COMPLETE AIR VALVE ASSEMILY AND TIGHTEN BODY TO 100
NO IN LOS. TOROUS ANDAEPLACE LOCK WIRE THEN INFLATE STRUT. 3 y/ o 710
stCTO INFLATE ŠThur : 31/4 735
5. REPLACE AND TIGHT CN VALVE CAP 31/0 703
3 701
TO INFLATE STRUT 27/0 126
I. ACMOVE VALVE CAP AND ATTACN AIR FILLER CHUCK TO MIGN PRESSURE 2 V4
AIR VALVE 26/0 099
2. LOOSEN TVIVEL NUT ( TURN COUNTERCLOCKWISE ) A MAX OF 2V2 TURNS 2 1/2 939
AND INFLATE STRUT USING AN 6206-2 PRESSURE GAGE ADJUST 2 3/0 106
PRESSURE IN ACCORDANCE WITN INFLATION INSTRUCTIONS . 2 1/4 103
3. TICHTEN SWIVEL NUT TO 60-70 IN . LOS . TONQUE (TURN CLOCKWISE ) 21/0 1092
ACMOVE FILER CHECK FOR LEAKS AND REPLACE VALVE 2 ISO
17/0 1222
IVA 1299
VA 2007
FULLY COMP
AM.209
Figure 12-17 . - Landing gear strut servicing instruction plate.
emergency landing gear extension , and behind the control panel and utilizes a source of
emergency canopy operation. low -pressure air to operate the booster or pump
Some aircraft have a pneumatic system which which is used to boost the nitrogen to the
will maintain the required pressure in these required pressure.
bottles in flight. However, most of these
Since gases expand with heat and contract
pneumatic systems require servicing on the
ground with an external source of high -pressure when cooled , air storage bottles are usually filled
air or nitrogen prior to each flight. to a given pressure at ambient temperature. A
The canopy bungee cylinder on the A -4E graph similar to that shown in figure 12-18 is
usually mounted on a plate or decal on or near
aircraft is an example of a storage unit which the bottle or air filler valve . If the instructions
requires pneumatic servicing. This unit aids in plate is missing or not readable the information
opening and closing the canopy and in
emergencies removes the canopy from the may be found in the General Information and
aircraft. The Maintenance Instructions Manual Servicing section of the applicable Maintenance
Instructions Manual.
specifies the use of high -pressure nitrogen in this
unit; therefore, the nitrogen booster is used in Pressure should be added to air storage bottles
servicing (See fig. 12-18 . ) slowly in order not to build up heat from rapid
The nitrogen booster shown in figure 12-18 transfer. Care should be taken to insure that air
has one 1,800 psi bottle of nitrogen enclosed storage bottles are not overinflated .
361
BUNGEE CYLINDER WARNING : RELEASE NITROGEN IN CYL
PRESSURE
BEFORE DISASSEMBLING 3000
INFLATION
100
PSI
+
INFLATION INSTRUCTION : 2800
CHART
-FILLER VALVE
1. WITH CANOPY IN OPEN POSITION
CHECK LATCH MECHANISM FOR 2600
-SWIVEL NUT POSITIVE ENGAGEMENT .
2. INFLATE CYLINDER PER 2400
INFLATION CHART WITH NITROGEN .
3. SEAT HEX . CAP AND CHECK VALVE, 2200
0 40 80 120 160
AND FILLER PLUG FOR LEAKS .
AMBIENT TEMPERATURE °F
DO NOT OVERINFLATE
PRESSURE GAGE
VALVE CAP
0 GREASE CYLINDER ROD PACKING
PER MIL - L- 4343
WARNING
V
WI
以
COCKPIT ENCLOSURE BUNGEE SAFETY PIN

MUST BE INSTALLED WHEN SERVICING,
TO PREVENT INADVERTENT CANOPY JETTISONING
COCKPIT ENCLOSURE
JURY STRUT
NITROGEN BOOSTER
09
0
Lic
ENTRANCE LADDER
AM.211
Figure 12-18 . - Servicing the A -4E canopy bungee system . the
tire
tem
Inflation of Tires. data may also be found in the General unde
Information and Servicing section of the wher
Correct air pressure must be maintained to applicable Maintenance Instructions Manual. T
receive satisfactory service from aircraft tires. Overinflation reduces the contact area of the checl
Air pressure must be checked daily with an tire, causing it to wear faster at the tread center. chart
accurate gage . Tires must be inflated to the Failure due to carcass ruptures and breaks in the RECE
pressures specified for the type of operation tire cords which result from contacts with presse
(ashore or afloat) and the gross weight of the foreign objects are usually caused by over would
particular type aircraft. Tire inflation data is inflation . pressi
usually found as illustrated in figure 12-19 . In Underinflation increases contact area and regar
case the plate is missing from the aircraft, this causes the tire to wear rapidly and unevenly at If
362
should be added from a regulated source .

CAUTION : An unregulated high -pressure air
source for tire inflation is a hazard . Tire
inflation source pressure should be carefully
monitored . If high - pressure cylinders such as the
portable air bottle or the air or nitrogen
servicing trailer are used , the regulator must be
used to prevent inadvertent overinflation .
A remote inflator unit should always be used
FWD when inflating tires. The operator of this unit
should always stand at right angles to the
RIGHT -HAND MAIN landing gear axle, directly in front or in the rear
MAIN LANDING GEAR DOOR of the tire . The operator should also stand at the
LANDING (LEFT -HAND DOOR full length of the inflator unit hose. This will
GEAR STRUT TYPICAL)
prevent the operator from being struck by pieces
of the wheel in case of failure .
CAUTION : When an aircraft wheel is to be
removed from the aircraft, the air must be
>
MAIN WHEEL TIRE

removed prior to removing the wheel. This
INFLATION PRESSURES precaution must be taken because of the
INFLATIO N
possibility that the bolts in split type wheels

INITIAL
360MTCARRIER BASED
might have been sheared from landing, thus
P-SI
340
320)
MAIN LANDING
causing the wheel halves to separate when the
300 GEAR WHEEL axle nut is removed . In the past, several people
BASE D
D
SLAN
280 TIRE INFLATION have been killed by their failure to remove the
260 PRESSURE CHART air from the tire before removing the axle nut.
240
220)
200)
10 12 14 16 18 20 22 AIRCRAFT LUBRICANTS
AIRPLANE WEIGHT 1000 LBS AND LUBRICATION
PLATE NO. 2679611
The proper lubrication of modern high -speed,
AM.212 high -altitude aircraft is an extremely important
Figure 12-19 . - Tire inflation chart. part of line maintenance. All maintenance
personnel should be familiar with the various
types of lubricants, their specific use , and the
the outer edges of the tread . An underinflated method and frequency of application .
tire flexes excessively and develops high
temperatures which weaken the tire cords. An LUBRICANTS
underinflated tire may also slip on the wheel
when landing and shear off the valve stem . Lubricants are substances which are spread in
To determine the proper inflation pressure, a thin coat or film over surfaces which move
check the inflation chart. For example, using the across each other to reduce friction and wear
chart in figure 12-19 , if the gross weight of the
> between the surfaces. Lubricants also help to
aircraft is 20,000 pounds , the correct tire dissipate heat generated in bearings , prevent
pressure for that aircraft when shore based corrosive attack on bearing surfaces, and protect
>
would be 310 psi. When carrier based , the the bearings from foreign particle contamina
pressure would be maintained at 350 psi tion . If adequate lubrication is not provided as
regardless of the gross weight . specified in the various inspection requirements
If the tire pressure is found to be low , air and Maintenance Requirements Manuals, bearing
363
failure, binding of mechanisms, etc. , can be > NOTE : MIL -G -81322 grease is not compatible
expected . with other lubricants. If it is to be used as a
Lubricants are classified as greases, oils, or dry
> recommended substitute for another type of
film lubricants. Greases and oils are the two grease , insure that all traces of the original grease
most common lubricants; however, certain dry are removed first.
film lubricants are in limited use and others are AIRCRAFT GENERAL PURPOSE
being evaluated . GREASE . -MIL -G -7711 is designated for use in
Greases used in roller element type bearings gear boxes , anti-friction bearings , and plain
generally consist of an intimate dispersion of a bearings where operation at both low and high
thickening agent with oil. The oil can be a temperatures ( -40° to +250° F) may be
petroleum derivative (mineral) or chemical required .
synthesis (synthetic) depending on the expected AIRCRAFT AND INSTRUMENT GREASE ,
temperatures encountered in its application. The GEAR AND ACTUATOR SCREW.
thickener keeps the oil in suspension and acts as MIL -G - 23827 is intended for use in ball, roller,
a reservoir. As the moving parts come in contact and needle bearings ; sliding and rolling surfaces
with the grease, oil adheres to the bearing of instruments, cameras, electronic gear, and
surfaces. Bleeding of the oil from the grease aircraft control surfaces; aircraft gears , actuator
takes place gradually so that a small quantity of screw mechanisms, and other equipment a
oil sufficient for proper operation is continuous requiring a lubricant with a high load carrying t
ly supplied . The oil that is picked up by the capacity over a temperature range between
moving parts of the bearing gradually deterio -100° to +250° F . It can withstand tempera
rates from the effects of oxidation , is lost by tures up to 300° F for short periods of time. C
evaporation , or is thrown free by centrifugal NOTE : MIL - G -23827 supersedes MIL L
force. As this process continues, the oil content G -3278 , 7118 , and 7421 , which are still listed in lu
of the grease is depleted and the lubricant will many Maintenance Instructions Manuals as of a
no longer give adequate service. It is for this this writing. MIL-G-23827 grease should not be 0
reason that during lubrication all the old used in contact with rubber and painted or cc
lubricant should be forced from each lubrication acrylic surfaces as it will damage these surfaces.
point until new lubricant appears. Bearings should be clean and free of other ti
greases, oil, and water before application . While
Types of Lubricants this is true in lubricating all bearings it is di
especially important when applying MIL
G - 23827 grease . SE
It is impractical to cover each type of fo
lubricant approved by NavAirSysCom and in use PNEUMATIC SYSTEM GREASE.
at the present time . The types of lubricants MIL - G -4343B is intended for use as a lubricant
recommended for various aircraft applications between rubber and metal parts of pneumatic
will vary with each type of aircraft to some systems. It is also used on pressurized cabin M
degree depending on the aircraft manufacturer. bulkhead grommets and other mechanisms
Some of the more common types are discussed where rubber -to -metal lubrication is required.
in the following paragraphs. MOLYBDENUM DISULFIDE GREASE.
AIRCRAFT GENERAL PURPOSE GREASE , MIL-G-21164C is intended for use as a lubricant ар
ap
WIDE TEMPERATURE RANGE . - MIL -G -81322 for accessory splines, heavy loaded sliding
is used in the lubrication of aircraft accessories surfaces, and for antifriction bearings carrying
operating at high speeds over a wide temperature high loads and operating through wide tempera GP
range (-65° to +350° F). It was specifically ture ranges. The molybdenum disulfide affords
designed for use in aircraft wheel bearings, better than average reliability in preventing or
anti -friction bearings, gear boxes, and plain delaying seizure in the event of marginal or
bearing applications that fall within the lul
inadequate lubrication .
operating temperature range . It is available in AIRCRAFT BALL AND ROLLER BEAR of
TIL
1 -pound cans, 35-pound pails, and 14 ounce ING GREASE . -MIL - G -25013D is intended for
use in antifriction bearings exposed to low COD
cartridges.
als
364
torque at temperatures as low as – 100° F and Grease guns are used in conjunction with
will provide adequate lubrication for extended " zerk ” fittings for lubrication of landing gear
periods at temperatures as high as +450°F . actuators and other similar components. The
NOTE : MIL -G -25013D supersedes MIL operation of the zerk fitting is similar to the
G - 27343A which may appear in some Main one-way check vlaves found in hydraulic
tenance Instructions Manuals and (03) Overhaul systems. When the grease gun is removed , a
Manuals. spring -loaded ball check is seated, preventing the
GENERAL PURPOSE GREASE. grease in the unit from escaping back through
MIL - G -23549A is a molybdenum disulfide fitting.
grease intended for general purpose use on A special flush type grease fitting is now being
automotive and ground support equipment that used on many installations to replace the old
could be exposed to high -pressure steam , salt zerk type fitting. They are press fitted into the
water, high load , and high temperatures and low unit and require a special lubrication adapter,
speed . It is not generally designed for aircraft which can be attached to the grease gun .
use . Figure 12-20 illustrates both types of guns
NOTE : In all cases utilize the type of with the adapter. The grease guns may be
lubricant designated in the General Information
and Servicing volume of the applicable Main
tenance Instructions Manual and the applicable
Maintenance Requirements Cards.
GENERAL PURPOSE LUBRICATING
OILS . - Oil procured under Specification MIL
L -7870 , is used primarily for general squirt can
lubrication . It is used on canopy tracks, aileron
and trim tab hinges, and many other locations .
on the aircraft where a light, low -temperature, LEVER TYPE
corrosion -preventive lubricant is required.

Federal Specification VV-L-800 is a preserva
tive type lubricating oil which contains cor
rosion and oxidation inhibitors and water
displacing agents. This type lubricating oil is
specified for use on most aircraft as a lubricant
for all piano hinges.
METHODS OF APPLICATION
The different types of lubricants can be

applied by any one of the following methods, as
applicable.
Grease Guns
Grease guns are used for general heavy -duty PRE TYPE
lubrication . There are numerous types and sizes
of grease guns available for different purposes.
The hand -operated type guns are the most
common ; however, pressure -operated types are AM.213
also available . Figure 12-20 . -Grease guns.
365
equipped with a flexible hose instead of the rigid and Servicing section of the Maintenance
extensions as shown in figure 12-20. instructions Manual. These instructions appear
in the form of tables and charts.
Oil or Squirt Can A table of lubricants similar to the one
illustrated in figure 12-21 lists all of the various
Oil or squirt cans are used for general types of lubricants to be used in lubricating the
lubrication , using the specified oils for the entire aircraft. Additional information , such as
component or part being lubricated . Always frequency symbols , application symbols,
check to make sure the squirt can contains the specification numbers and symbols, and the
proper lubricant before using it . NATO symbol, is provided on this table.
The lubrication of most new type aircraft is
Hand performed using the applicable Maintenance
Requirements Card as a guide. Lubrication is
This method of lubrication is generally required at the intervals specified on the various
employed for packing wheel bearings. Maintenance Requirement Card sets (Preflight,
Daily, Postflight, Special (7 day, 14 day , etc.),
Brush Conditional , and Calendar). Figure 12-22 il
lustrates the front and back of one of these
This method of lubrication is employed when cards which covers the lubrication of the A -4E
it is necessary to cover a large area with a aircraft. The card shows the types of lubricants
lubricant or for coating tracks and guides. required , number of lubrication points, an
illustration of the unit to be lubricated, and the
LUBRICATION CHARTS method of application .
NOTE : The frequency symbols used in figure
The lubrication requirements for each model 12-21 are not necessarily standard for all
of aircraft are given in the General Information aircraft. In reading the lubrication chart for a
TABLE OF LUBRICANTS
FREQUENCY SYMBOLS
MILITARY NATO SPECIFICATION
SYMBOL SYMBOL NOMENCLATURE NUMBER
NONE ANTISEIZE COMPOUND, FEL-PRO (-5

FELT PRODUCTS CO. , CHICAGO, ILL.
.
CT CORROSION PREVENTIVE COMPOUND, MIL-C- 16173,

SOLVENT CUTBACK , COLD APPLICATION GRADE 3 AND 4
ODD EVEN
BRW GREASE, AIRCRAFT, BALL AND ROLLER MIL - G - 81322A INSPECTION INSPECTION
BEARING, WIDE TEMPERATURE RANGE
GIA G - 354 GREASE, AIRCRAFT AND INSTRUMENT MIL - G - 23827
GEAR AND ACTUATOR SCREW
GGA G - 355 GREASE, GRAPHITE, AIRCRAFT MIL -G - 7187
LUBRICATING
GMD GREASE , MOLYBDENUM DISULFIDE MIL - G - 21164 SPECIAL
OHC C -635 HYDRAULIC FLUID , PETROLEUM MIL -H - 6083
BASE, PRESERVATIVE
GPS LUBRICATING GREASE , PNEUMATIC SYSTEM MIL - G - 4343
GREASE GUN
OGR LUBRICATING OIL, GEAR, PETROLEUM BASE MIL- L- 6086
OGP 0-142 LUBRICATING OIL , GENERAL PURPOSE LOW MIL- L- 7870 OIL CAN BRUSH HAND
TEMPERATURE ADP
PL - SPECIAL LUBRICATING OIL , GENERAL PURPOSE, VV - L - 800 ADAPTER FOR GUN
PRESERVATIVE
NONE MOLYBDENUM DISULFIDE POWDER, MIL-M - 7866
LUBRICANT
AM.214
Figure 12-21 . - Table of lubricants for an aircraft.
366
TASK WORK CARD PUBLICATION NUMBER CHANGED ELEC PWR OFF

MIN AREA 49.4 NAVAIR 01-40AVC - 6-4 HYD PWR OFF
5.0 2 3. Lubricate Forward and Aft Nose Landing Gear Doors as follows :
ITEM NOMENCLATURE NO . OF POINTS SPECIFICATION
i
1. Nose Landing Gear Actuating
1
2.
cim Cylinder Upper Fitting
Nose Gear Aft Door Hinge
2
1
MIL - G - 21164
MIL - L - 7870
3. Nose. Landing Gear Position
Indicating Pin 1 MIL - L - 7870
4. Forward Door ( fore and aft )
Latch Mechanism Actuating
Cylinders 2 MIL - G - 21164
5

Latch Moving Parts (except
sealed bearings ) 2 MIL - L - 7870
Latch Hooks 2 MIL - G - 21164
(A )
CARD PUBLICATION NUMBER FORWARD AND AFT NLG CHANGED
49.5 NAVAIR 01-40AVC -6-4 DOORS LUBRICATION

2G-1164
G-21164
7L-870
INDICATING
ACTUATING
CYLINDER
POSITION
FORWARD
LATCHES
2G-1164
DOOR
9
NLG
AND
PIN
S.
L-7870
)(FWD
AFT
AND
HINGE
DOOR
AFT
COM)I
1-7870
(B)
AM.215
Figure 12-22. - Maintenance Requirements Card for lubricating an aircraft (A) Front; (B) back.
367
particular aircraft, always refer to the applicable (MAF's, and SAF's, etc.) have been complete
table of lubricants for the correct interpretation and turned in for processing. Throughout thi
of all symbols. manual various examples of this documentatio
have been shown with their intended use .
GENERAL LUBRICATION In order to achieve the highest possible stat

PROCEDURES of aircraft readiness and reliability at the lowes
cost in manpower, money, and material
maintenance documentation cannot be Over
Prior to lubricating any components or parts,
stressed . Detailed instructions on the 'use and
all foreign matter should be removed from
joints , fittings, and bearing surfaces. A clean soft preparation of the various maintenance docu
cloth saturated with a cleaning solvent can be ment forms are provided in Military Require
used for this purpose. The lubricant should be ments for Petty Officer 3 & 2, NavPers 10056
applied sparingly to prevent accumulation of ( Series) and OpNav Instruction 4790.2 (Series ).
dust, dirt, and other foreign matter.
When applying lubricants through pressure
AIRCRAFT JACKING
type fittings with a grease gun , make sure the
lubricant has emerged around the bushing. If no
grease appears around the bushing, check the The AMS should be familiar with the jacking
of an aircraft in order to be able to assist in
fitting and grease gun for proper operation.
Always make sure the grease gun is properly performing routine maintenance . Since jacking
attached to the fitting and wipe up all excess procedures and safety precautions vary for
grease when finished . If the new flush type different types of aircraft, only general jacking
procedures and precautions are discussed in this
fitting is being used , the grease gun must be
equipped with the flush type adapter, and it chapter. Consult the applicable Maintenance
Instructions Manual (General Information and
must be held perpendicular to the surface of the Servicing section) for specific jacking proce
fitting when greasing, if possible. dures.
NOTE : Some of the high -speed mechanisms
on modern aircraft are critical as to the lubricant The aircraft to be jacked must be located in a
required . If the exact lubricant specified in the level position , well protected from the wind . A
Maintenance Instructions Manual cannot be hangar should be used if at all possible. The
Maintenance Instructions Manual for the aircraft
obtained , and there is no substitute listed, a
being jacked should be checked for the location
substitute should be requested from higher of the jacking points. These jacking points are
authority, and only their recommended substi
tution should be used . usually located in relation to the aircraft center
of gravity so that the aircraft will be well
Clean up all spilled or excess oil or grease balanced on the jacks . However, there are some
after the aircraft is lubricated . Never allow oil or exceptions to this. On some aircraft it may be
grease to come in contact with oxygen necessary to add weight to the nose or tail to
equipment . Some types of synthetic compounds achieve a safe balance . Sandbags are usually used
are harmful to rubber, neoprene, and electrical for this purpose .
material . They will also soften paint and should
be removed as soon as possible with a clean Tripod jacks similar to the one shown in
cloth . figure 12-23 are used when the complete aircraft
is to be jacked. A small single -base jack similar
to the one shown in figure 12-24 is used when
MAINTENANCE DOCUMENTATION only one wheel is to be raised . The jacks used
for jacking aircraft must be maintained in good
The numerous maintenance tasks that are condition; a leaking or damaged jack must never
performed on the line are never complete until be used . Also each jack has a maximum
the necessary maintenance documentation capacity , which must never be exceeded.
1
368
JACK THREADED
PISTON EXTENSION
JACK PISTON
LOCK NUT
PUMP
PUMP
HANDLE
JACK RELEASE
VALVE
M
O
R
E
AM.216
Figure 12-23 . - Typical tripod jack.
AM.217
PROCEDURE FOR JACKING Figure 12-24 . - Typical single-base jack.
COMPLETE AIRCRAFT
Prior to the actual jacking of the aircraft, an jack pads. A final check for alignment of the
overall survey of the complete situation should jacks should be made before the aircraft is
be made to determine if any hazards to the raised , as most accidents that occur during
aircraft or personnel exist. Tripod jacks of the jacking are the result of misaligned jacks. Figure
appropriate size for the aircraft being jacked 12-25 illustrates two typical types of jack pads .
should be placed under the aircraft jacking When the aircraft is ready to be raised a man
points and perfectly centered to prevent them should be stationed at each jack . The jacks.
from cocking when the aircraft is raised . The should be operated simultaneously to keep the
legs of the jacks should be checked to see that aircraft as level
level as possible and to avoid
they will not interfere with the operations to be overloading any of the jacks. This can be
performed, such as retracting of the landing accomplished by having the crew leader stand in
igear, after the aircraft is jacked . front of the aircraft and give instructions to the
Jack pads, which are used as adapters between men operating the jacks. Figure 12-26 illustrates
the jacks and the aircraft jacking points, are an aircraft being jacked .
carefully installed and must fit perfectly. The CAUTION : On many jacks the piston can be
jacks should be extended until they contact the raised beyond the safety point ; therefore, never
369
minimum , and no violent movements should

made by persons who are required to go aboar
Safety jacks or cradles designed to support ti
aircraft while on jacks should be put in place
soon as possible, particularly if the aircraft is
remain jacked for any length of time .
Jacking procedures aboard ship require a
extra
measure of caution because of shi
movements . Permission to jack the aircraft mus
be given by the activity's maintenance control
G
WING JACK PAD ASSEMBLY
No jacking will be authorized unless the weathe
is calm and the ship is expected to be on a
straight course during the time the aircraft wil
be on jacks.
Figure 12-27 illustrates the shipboard jacking
arrangement for the A -4E aircraft. Additional
TD- 1 tiedown chains may be utilized to anchor
the jacks in position as a further measure of
safety . Additional tiedown chains may also be
added to landing gear and other tiedown attach
points if drop checking operations permit.
When removing the aircraft from the jacks,
insure that all obstructions, including stabilizing
jack , are clear of the aircraft. The same number
6863 of people are required as for jacking. The jacks
should be pumped up slightly to release the
piston lock nuts. The locknuts should be turned
FORWARD JACK FITTING upward on the piston screw threads at about the
same rate as the pistons are descending. The
AM.218 level attitude of the aircraft should be
Figure 12-25 . - Typical jack pads. maintained at all times . Removal of the jack
pads from the jack receptacles should be
accomplished as soon as the jack is moved clear.
raise an aircraft any higher than is necessary to The weight of the pad is generally enough to
accomplish the job at hand . cause the pad to fall out of its receptacle or if
CAUTION : Avoid overextension of the not removed immediately the possibility of
threaded extension . While its compression overlooking their removal exists. In either case, a
strength is equal to the compression strength of safety hazard is caused . More than one case of
the jack as a whole , its thin cross -sectional area an aircraft flying with the jack pad in its
makes it particularly susceptible to bending and receptacle has been recorded and points to the
breaking under side loads , especially when near fact that human error can go undetected. While
its full extension . errors of this sort should have been noticed by
NOTE : While jacking, the piston lock nuts the supervisor, quality assurance inspector, the
( fig. 12-23 ) should be moved down as the piston plane captain , and the pilot who ultimately flew
is raised . This will prevent the jack from the aircraft, the maintenance man should not
collapsing in the event of a sudden loss of fluid . rely on others to see a job through to a safe
When jacking is complete, the locknuts should completion.
be locked snugly against the jack body . NOTE : When lowering some aircraft from
The area around the aircraft should be jacks, it is necessary to place metal plates ( skid
secured while the aircraft is on jacks. Climbing plates) under each tire on the main landing gear.
on the aircraft should be held to an absolute These skid plates must have a film of grease
370
NOTE
WING JACK PAD ASSEMBLY If major equipment has been removed from
forward fuselage and engines are installed ,
use aft fuselage jack point to steady aircraft .
FORWARD JACK FITTING
EX
t a
n o
1. Defuel aircraft to landing weight to reduce

structural loads .
2. Inflate landing gear struts . WARNING

See Warning note .
3. Install forward fuselage and wing jack pads .
Lower aft fuselage jack before any other jacks
4. Jack wing and forward fuselage points evenly . to prevent structural damage .
5. When aircraft is jacked to desired height , set Do not use more than 1000 PSI air .
ram safety nuts . source when inflating struts .
AM.219
Figure 12-26 . - Jacking a complete aircraft.
between them to allow the upper plate to skid as tailwheel, it must be locked . The wheel should
the weight of the descending aircraft increases, be raised only high enough to clear the deck.
permitting the main gear to assume its neutral Figure 12-29 shows a wheel being raised using a
rest position (See fig. 12-28 .) single -base jack.
PROCEDURE FOR
JACKING ONE WHEEL MISCELLANEOUS GROUND
HANDLING EQUIPMENT
When only one wheel has to be raised , as for
changing a tire or greasing wheel bearings, a When assigned to the line division , the
single -base jack is used. Before the wheel is AMSAN AMS3 may be required to assist in the
raised , the remaining wheels must be chocked starting of aircraft engines or ground testing of
fore and aft to prevent movement of the various items of aircraft equipment. To do this it
aircraft. If the aircraft is equipped with a will be necessary to know how to operate
371
AIRCRAFT TIEDOWN BAR
= A -4E AIRCRAFT
I
AM. 1213
Figure 12-27 . -Shipboard jacking arrangement - A -4E.
equipment such as mobile electric powerplants coverage is provided in this manual on the NC --5
and gas turbine compressors. Special training and the NC-7B .
and in some cases licensing is required of Operation and servicing instructions for the
operators of such equipment . various types of mobile electric powerplants can
be located by referring to the applicable NavAir
19 (Series) Operating and Servicing Manual for
MOBILE ELECTRIC the specific model equipment as listed in the
POWERPLANTS ( MEPP) NavAir Publications Index, NavAir 00-500A .
There are many different types of mobile NC - 5 Power Unit
electric powerplants in common use. Some types
are self-propelled and others must be pushed or The NC-5 is a self-propelled electric power
towed to the aircraft which is to be serviced . unit. It may be driven from place to place in the
The NC-5 , NC-7 , NC- 10/ 10A, NC -12 and 12A, same manner as any other motor vehicle.
and the Mobile Motor Generator (MMG) units It has provisions for delivering three different
are still in use throughout the Navy and possess kinds of power-constant voltage variable
similar controls and operating features. Since current d-c electrical power for starting jet
special training is required and provided by aircraft engines; constant voltage d-c power for
ground support equipment personnel to insure starting reciprocating aircraft engines or jet
that such equipment is operated only by fully aircraft engines in aircraft having a single bus
qualified operators, only brief descriptive type electrical system ; and 115 /200 - volt,
372
1113 JACK PAD
!! EM
!!
GREASE
12 INCHES is
LOWER
SKID 2 INCHES
UPPER PLATE
SKID
PLATE
WHEEL
JACK
VIEW LOOKING FORWARD
AM.220
AM. 1227 Figure 12-29. Jacking one wheel .
Figure 12-28 . -Skid plate .
cause damage to the structure around the
3 -phase, 400-Hz alternating current for checking receptacle.
and operating a - c equipment, each through a Insure that the power unit exhaust is not near
separate cable. the skin of the aircraft. The heat from the
The power cables are plugged into the aircraft exhaust could cause damage to the skin or the
electrical system at an external power recep paint finish .
tacle. Figure 12-30 shows the NC - 5 and the Servicing an aircraft with an NC-55 should
external power receptacle similar to that found always be a two -man job. The driver should
on most new aircraft. Aircraft with this type remain at the wheel and operate the generator
external power receptacle require the use of drive unit and the throttle . The second man
only one type power, 115 /200 -volt, 400 -Hz should operate the unit's electrical system and
alternating current (a.c. ). plug the power cables into the aircraft.
Some aircraft require the use of 28 -volt direct Before engaging the generator drive unit,
current (d.c. ) for starting reciprocating engines. make sure that the transmission is in neutral.
Figure 12-31 shows the external power recep Much damage is caused throughout the Navy by
tacle used on an aircraft which requires both carelessness in the operation of mobile electric
400 -Hz a.c. and 28 volt d.c. NOTE : The shape power units. No one should attempt to operate
of the plug and the spacing of the pins in the any type of mobile electrical equipment unless
receptacle make it impossible to plug the wrong he is a qualified operator. NOTE : Ground
type cable into the aircraft. support equipment schools are being operated at
When applying electrical power to an aircraft, all naval air stations to train operators of units
park the NC-5 in a position so that the cable will such as the NC-5 . All activities require a special
reach without causing a load on the external operator's permit for the operators of these
power receptacle. The weight of the cable might units.
373
fico
A-C EXTERNAL POWER SWITCH GUARD
DI
A-C EXTERNAL POWER SWITCH
POWER DISCONNECTED POWER CONNECTED
3
C
A.C MOBILE ELECTRIC POWER PLANT
EVERNAL KRNALY RECEPTACLE GUARD

( OPEN POSITION)
ANAL INTE
POWER PLANT CABLE PLUG
AM.221
Figure 12-30. - External power application using NC-5 mobile electric power unit.
After completing the turnup or checkout of by a V-8 gasoline engine and contains two d-c
equipment , the power cable should be removed generators, an a - c generator, a control console
from the external power receptacle and stowed for control of the engine and both electrical
in the container which is provided on the unit. systems, and a propulsion system for moving the
Many times a year aircraft are damaged by unit under its own power. Access doors are
careless NC - 5 operators driving off from the provided for the control, console , engine,
aircraft with the cable still plugged in . Care battery , cable stowage , and tool compartments.
should be taken to insure that the cable is not The a - c electrical power system provides
dragged on the taxi way behind the power unit. 120 / 208 -volt 3 -phase, 400 -Hz power for
Dragging severely damages the cable , and cables servicing aircraft a-c components. The d - c
are quite expensive. Before driving the unit away generators provide an output of 28 volts and are
from the aircraft, check to insure that the rated at 750 amperes continuous and 1,000
generator drive unit is disengaged. amperes intermittently. The outputs from the
two d-c generators are used for jet engine
NC - 7 Electric Power Unit starting and servicing d-c components . Also , the
output from one of the d-c generators is used to
The NC-7 shown in figure 12-32 is powered power the self-propulsion system .
374
A hand control unit is provided on the tow

bar for controlling the unit during self -propelling
AC POWER RECEPTACLE operations.
113/200 VOLT, 39 , 400 HZ
7 ‫د د د د د‬ ပ၁ ၁ CAUTION : Do not move the power unit by
၁
• means of the self-propulsion mechanism while
DC POWER RECEPTACLE
28 VOLT DC supplying power to an aircraft. Under ng
condition is the unit to be used as the prime
"BO" mover for towing other equipment .
O
'0 The self-propelling feature should be used
s only when moving from one aircraft to another
"O or from the line to the hangar and back as
necessary if the distance is not too great. For
ACCESS DOOR greater distances the unit should be towed .
૦ ૦ ૦ ૦ ૦ Most of the electrical power units tend to be
slightly topheavy. When driving or towing such
units the speed should be held to a minimum to
prevent the possibility of turning the unit over,
AM.223 For example , the towing speed for the NC-7 is
Figure 12-31. - External power receptacle. 20 MPH maximum .
CONTROL CONSOLE ENGINE ACCESS DOOR

18
oc
多
USN
55-03234
0
FIRE EXTINGUISHER BATTERY COMPARTMENT
AM. 1214
Figure 12-32. - Mobile Electric Powerplant ( NC-7B).
375
GAS TURBINE COMPRESSORS NOTE : The NCPP- 105 flyaway assembly

cannot be hung as an external store and must be
The gas turbine compressor is used to provide transported inside a transport or cargo type
pneumatic power in the form of compressed aircraft.
bleed air for the operation of pneumatic The control panel , shown in figure 12-35, is
equipment . Such as aircraft engine starters and part of the flyaway assembly and is located on
air -conditioning systems , and for testing units one end of the NCPP -105 unit. The control
such as the ram -air turbine. Gas turbine
compressors are largely self-contained and
panel contains the operating instructions for the
operation of the unit . Table 12-1 is a list of all
require only an outside source of fuel and oil to the controls, indicators, and connectors located
maintain a constant output .
on the NCPP - 105 control panel and should be
The model NCPP- 105 compressor power unit , used in conjunction with figure 12-35 .
shown in figure 12-32 , is a complete, self The NCPP -105 is intended for ground use
contained unit consisting of a flyaway assembly only and because it is skid -mounted , should be
enclosed in a skid-mounted , weather-resistant strategically placed along the line so that it can
enclosure. Some models of the NCPP - 105 are
be used to service more than one aircraft
mounted on trailers for ease of movement from
without having to be moved .
aircraft to aircraft or place to place . The
NCPP - 105 supplies compressed air, at two Only qualified operators should attempt to
pressure ratios ( 5 : 1 and 3.6 : 1 ) , for aircraft operate this type equipment. Training on this
engine starting, and a - c and d-c electrical power type equipment is usually included in the
for operation of aircraft a-c and d - c electrical aviation support equipment school operated at
components . The NCPP- 105 is equipped with a naval air stations .
remote cable assembly , an a-c output cable , a d-c Gas turbine compressors may be damaged by
output cable , and aa bleed air duct assembly . trash, tools , or other foreign objects which may
The unit enclosure consists of a forward and be left near the inlet duct . When the compressor
aft enclosure (hinged together ), a cable stowage is operating, the following precautions should be
enclosure , muffler assembly , fuel tank , structure adhered to :
assembly , and a base assembly .
The flyaway assembly , shown in figure 12-34 , 1. Stand clear of the air inlet . Like aircraft jet
is normally operated while in the NCPP- 105 unit engines, these units take in large quantities of
enclosure , with the d-c power supply mounted air .
in the forward enclosure . However , when it is 2. Stand clear of the exhaust , and position
required to transport the flyaway assembly by the unit so that the exhaust does not strike the
aircraft to a temporary location, the d-c power aircraft.
supply is removed and relocated on the flyaway 3. Stand clear of the plane of rotation of the
assembly structure. The fuel line and a-c and dc turbine compressor. This area is clearly defined
electrical output cables are disconnected , the and marked on the equipment .
forward and aft enclosures are lifted off the 4. Do not connect or disconnect the ducting
structure assembly , and the flyaway assembly is while the unit is operating.
then removed from the base assembly. The 5. Do not connect or disconnect the
flyaway assembly, with its remote cable, a - c and electrical cables while the switches are ON .
d-c electrical output cables, and bleed air duct 6. After servicing the aircraft, always stow
assembly , upon arrival at its temporary location, the cables and ducting in the space designed for
can be operated by attaching it to aa fuel supply . them .
376
MUFFLER ASSEMBLY
BLEED AIR
OUTLET
CABLE
STOWAGE
KERT ( UM
ENCLOSURE WATU
19
CONTROL
PANEL
ASSEMBLY
STRUCTURE ASSEMBLY "
BASE ASSEMBLY
BLEED AIR DUCT STOWAGE
FORWARD AND AFT

ENCLOSURE ( HINGED )
FUEL TANK
AM.903
Figure 12-33. -Model NCPP - 105 compressor power unit.
. 377
DC POWER SUPPLY
( RELOCATION )
AM.904
Figure 12-34 . - NCPP -105 flyaway assembly .
378
2 3 5 6 7
27 8
l'eau
file
9
26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
28 29 30 31
STOLI
FEL
FEBI
ப Junm
ou thina01
34 33 32
AM.905
Figure 12-35 . - NCPP - 105 control panel.
379
Table 12-1 .-Controls, indicators, and connectors- NCPP- 105.
Preliminary
Index No. Function
Nomenclature Setting or
( figure 12-35) Indication
1 Indicator (M1) Indicates engine rpm in percentage . zero
2 Dome Assembly (DS7) Illuminates panel. off
3 Meter (M6) Indicates a -C voltage . zero
4 Dome Assembly ( DSB ) Illuminates panel. off

5 Meter (M5) Indicates a-c amperes . zero
6 Dome Assembly (DS9) Illuminates panel. off
7 Meter (M4) Indicates d -c amperes . zero
8 Meter (M3) Indicates d -c voltage. zero
9 Switch (88) Selects meter indication of output OFF

or battery .
10 Switch (87) Controls d-c power . OFF
11 Dome Assembly (DS4 ) Indicates d-c power . off
12 Dome Assembly (DSC) Indicates a-c overvoltage. off
13 Dome Assembly (DS5) Indicates a-c power . off
14 Switch (36 ) Selects meter indication of a-c phase. OFF

15 Illuminates panel. off
Dome Assembly (DS11)
16 Switch (S5 ) Controls and resets a-c power output. OFF
17 Circuit Breaker (CB2) Controls control circuit . off
18 Circuit Breaker (CB1) Controls power switches. off

19 Switch (S4) Controls panel lights . OFF
20 Dome Assembly ( DS10 ) Illuminates panel. off

21 Switch (S3 ) Selects air ratio output. OFF
22 Dome Assembly (DS2) Indicates airflow . off
23 Indicates ready for power delivery . off

Dome Assembly (DSi)
24 Indicates high oil temperature. off
Dome Assembly (DS3)
25 Switch ( S2 ) Controls power to starter relay . off
26 Switch (S1) Controls power to panel. off
27 Indicator (M2) Indicates engine exhaust temperature . zero
28 Indicates engine air pressure . zero

Gage
29 Indicates engine oil pressure . zero
Gage
30 Circuit Breaker (CB3) Controls power to starter . closed
31 Circuit Breaker (CB5) Controls d-c power to output cable . closed
-
32 Receptacle ( 12) Auxiliary d-c starting and charging

input.
-
* 33 Receptacle (J10) Connection for remote cable .

C
34 Plug ( J11) Provision for battery heater .
*Used on power units bearing Part No. 64A90 - F1. For power units bearing Part No. 64A90- F1-2,
connection for remote cable is located on the aft enclosure.
380
INDEX
Accessories manuals, 22
tread , 240-241
Acrylic lacquer , 317-318 types , 242
Advancement , 3-10 inflation , 252-253 , 362-363
active duty requirements, 5 maintenance , 245-246
inactive duty requirements, 6
mounting and dismounting, 246-252
preparing for, 4-10 preventive maintenance , 254-256
qualifying for, 4 retreading and repair, 253-254
Air storage bottle servicing, 360-361 storage, 244
Aircraft Application List, 14 Airframe construction :
Aircraft cleaners, 288-290 fixed wing, 57-72
Aircraft cleaning equipment, 290-291 arresting gear, 71
Aircraft cleaning procedures, 291-293 control surfaces, 63-66
Aircraft handling : flaps, wing, 65
firefighting procedures, 346-347 fuselage , 57-59
protective covers, 340-341 landing gear, 66-72
safety precautions , 341 slats, 66
spotting aircraft, 337 speed brakes, 66
surface control locks , 338 spoilers , 65-66
taxi signalman , 333-334 spring tabs, 65
taxi signals, 334 stabilizers , 62-63
tiedown procedures , 337-340 tabs, spring, 65
tow bars, 335-337 tabs, trim , 64-65
towing aircraft, 334-335 tail gear, 69-71
Aircraft jacking, 368-371 tail skag, 71-72
Aircraft lubricants, 363-364 wings, 59-62
Aircraft manuals , 17-22 rotary wing , 72-76
Aircraft preservation , 295-298 fuselage, 72
Aircraft servicing, 347-363 landing gear, 72-73
air bottles , 360-361 pylon , 75-76
air compressors, 359 rotary rudder blades , 76
defueling, 351-352 rotary rudder head , 76
rotor head , 75
engine oil , 352-354
fueling, 347-351 rotor wing , 74-75
Airloc fasteners, 127-128 , 207-209
hydraulic system , 354-355 Air valves, 360
pneumatic system , 355 , 357-361
shock struts, 359-360 Aliphatic naphtha , 288
Allowance lists, 17
tire inflation , 362-363
Alloying of metals, 35
Aircraft spotting, 337 Aluminum alloys, 37-42
Aircraft tiedown , 337-340
Aircraft tires : Aluminum , corrosion of, 302
AM rating, 1-3
Construction , 239-244
identification, 243-244 duties, 3
paths of advancement for, 1-2
381
AVIATIONSTRUCTURAL MECHANICS 3 & 2
Approach magazine , 27 idler arms, 154

Armed aircraft precautions, 345 push-pull rods, 154
Aromatic naphtha , 288-289 Copper and copper alloys, 42-43
Arresting gear, 71 Copper, corrosion of, 302-303
Corrosion control , 284-332
Bar folder, 112 appearance of corroded parts , 302-303
Bars, tow, 335-337 chemical surface treatments , 314-316
Bellcranks , 154 corrosion control kit , 315-316
Bend allowance , 114-116 corrosion elimination ,, 306-316
Beryllium copper, 43 removal of corrosion , 307-314
Blast , vapor, dry honing, 310-314 vapor blasting , 309-314
Blind rivets, 121-123 , 188-197 removal of paint , 307
Bolts, 129-133 corrosion prone areas , 298-302
Brake : covers and shrouds , 293 , 295
box and pan , 111-112 damage limits , 314
cornice , 109-111 detection methods , 45-51 , 306
Brakes , overheated , 342-345 penetrant inspections , 45-51
Bronzes, 42-43 interpreting results, 50-51
Bucking bars , 87-88 forms of corrosion, 303-306
Bulletins, 24-26 ground handling requirements, 295
Bungees, 154 painting , aircraft, 316-328
preservation , aircraft, 295-298
Cables, 146-147 preventive maintenance , 287-298
fittings, 147 sealants, 328-332
guides , 150 surface maintenance , 287-293
Cadium , corrosion of, 303 cleaning methods, 291-293
Camloc fasteners, 125-126 , 203 , 205-206 materials, 288-290
Carbon steels , 36 Vacu -Blast dry honer, 310-314
Casting alloys , aluminum , 41 Countersinking :
Changes, aircraft, 24-26 dimple , 181-185
Chrome-molybdenum steel, 37 machine , 185
Chrome -nickel ( stainless steels ) , 37 Coupling, V-band , 144
>
Chrome - vanadium steels , 37 Covers and shrouds, use of, 293-295

>
Chromium steels , 37 Cutting tools , 90-91

Clamps, installation of, 281-282
CO2 bottles, 346 Damage classification , 155
Compressors, 359 Defueling, 351-352
Connector links, adjustable , 149 Dimpling, hot , 181-185
t
Cont
• rols , mechanical , 144-154 Directional flight, 83-84
cable system , 146-154 Directives Application List , 14
cable fittings, 147 Dissimilar metal corrosion , 305
cable guides , 150, 152 Drilling rivet holes , 179-180 Fati
cables , 146-147 Drycleaning solvent, 288 Ferr
connector links, adjustable, 149 Dye penetrant inspection , 45-52 Filifc
pulleys , 152-153 Dzus fasteners, 128, 206-207 Firef
quick disconnects, 149 , 151 Flaps
sectors and quadrants, 153-154 Edges, reinforced , 112-113 Flare
turnbuckles, 148-149 Ejection seat hazards, 342 Flare !
rigid control systems , 154 Electric power units : Flexil
bellcranks and walking beams, 154 NC-5 , 372-374 fab :
bungees, 154 NC-7 , 374-375
inst
382
INDEX
Emulsion cleaners, 289 Flight control surfaces, 63-66

Enamel finishes, aircraft, 319 basic controls, 63-64
Engine oils, 352-354 miscellaneous flight controls, 64-66
Enlisted rating structure , 1 slats , 66
Epoxy primer, 317 speed brakes , 66
Equipment Applicability List , 13-14 spoilers , 65-66
Equipment and Subject Applicability List , 14 spring tabs , 65
Extractors, screw and bolt , 98 trim tabs , 64-65
wing flaps, 65
Flight control systems :
Fasteners : maintenance , 213-224
Heli-Coil inserts , 133-134 control cable , 213-218
Hi- Lok , 133 push-pull linkage, 218
Jo -Bolt, 134 removal and installation , 222-223
lockbolt, 124 rigging, 220-222
miscellaneous : troubleshooting , 218-220
pins , 140-141 rigging rigid controls, 221-222
cottes , 141 balance, 223-224
flathead , 140-141 turnbuckles, 221
tapes , 140 Flight deck safety , 345
rivets ( See Rivets . ) Flight line safety , 341-345
skin : Fluid line identification , 258-259
Cleco , 88-89 Flush patch , 160-163
threaded , 129-134 Forms of corrosion , 303-306
bolts , 129-133 Fretting corrosion , 305-306
heads , 130-131 Friction lock rivets, 122 , 188-189
>
identification , 131-133 Fuselage ( fixed -wing), 57-59

material, 131 Fuselage ( rotary -wing), 72
>
threads, 131 Fuselage sections, aft, 224-227

nuts, 135-136 installation , 225-227
nonself-locking, 135 removal, 224-225
self-locking, 135-136
screws , 139-140
machine , 139-140 Galvanic metal corrosion , 305
self-tapping, 140 Gas turbine compressors , 376
setscrews , 140 Gravity fueling, 349
structural , 139
turnlock , 124-128
Airloc, 127-128 Handtools, 86
Camloc , 125-127 Hardness testing methods, 36
Dzus , 128 Heat treatment , 33-35
Fatigue corrosion , 305 Heli-Coil inserts, 133-134
Ferrous aircraft metals, 35-37 Hi-lok fasteners, 133 , 199-201
Filiform corrosion , 306 Hi-Shear rivets, 120-121 , 197-199
Firefighting procedure , 346-347 Hole finder, 88
Flaps, wing, 65 Hose , flexible :
Flared -tube fittings , 261 rubber, 274-279
Flareless -tube fittings , 261 Teflon , 279-281
Flexible hose ( rubber ) , 274-279 Hovering, 81-83
fabrication and replacement, 276-277 Hydraulic fill stand , 355
installation , 277-279 Hydraulic system servicing, 354-355
383
Identification of aluminum , 38-40 squaring, 101 Painting, ai

Idler arms, 154 throatless, 101-102 Paints, airco
Illustrated Parts Breakdown , 21 unishear, 102 Patches:
Inner tubes, 256-257 turrent punch, hand operated, 102 flush, 16
Inspection of metals , 45-52 Metal forming machines, lap, 159
penetrant, 46-51 bar folder, 112 Penetrant
interpreting result , 50-51 brake : 109-112 Periodic M
Instructions and Notices, 26-27 box and pan , 111-112 Personnel
Intergranular corrosion, 304-305 cornice, 109-111 Plane direc
Iron and steel, corrosion of, 302 rotary machine, 105-107 Plastic en
slip -roll forming machine, 102-105 installm
Jack pads, 369-370 Metal lip -seal fittings, 261-262 removir
Jacking, 369-371 Metal working processes, 31-33 surface
Jo -Bolt, 134, 202-203 Metals, aircraft, 28-45 Plastics:
alloying of, 35 reinfor
K-Monel, 43 ferrous aircraft metals, 35-37 transp:
hardness testing, 36 Pneumat
Landing gear ( fixed -wing ), 66-72 SAE numerical index , 35-36 Polyuret
arresting gear, 71 types, characteristics, and uses, 36-37 Powerpla
main landing gear, 67-69 heat treatment, 33 , 35 Preserva
nose gear, 69-70 aluminum and its alloys, 37-42 Preserva
tail gear, 69-71 copper and copper alloys, 42-43 Presetti
tail shag , 71-72 magnesium and magnesium alloys, 43-44 Pressure
Landing gear (rotary -wing ), 72-73 nonferrous aircraft metals, 37-44 Pressur
main landing gear, 73 titanium and titanium alloys, 42 Protect
tail landing gear, 73 properties , 28-30 Publica
Lap patches, 159-160 qualities, 30-31 Inde
Layout practices, 116, 118 substitution and interchangeability, 45 A
Leadership , 3 Methyl ethyl ketone (MEK ), 289 D
Letter type publications, 24-27 Microbiological corrosion , 306 EO
Line operations, 333 Mineral spirits, 288
Lock rivets: Monel , 43 Ec
friction, 122 N
mechanical, 122 NATOPS Flight Manual , 17
Naval Aviation News, 27 U
Lockbolt , 124, 199 lette
Locking devices, 338 NavTra 10052 , 9
Navy Training Manuals, 9-10 В.
Lubricants, 363-365
NC - 5 power unit, 372-374 C
Lubrication charts , 366
NC-7 power unit, 374-375 In
Nickel , corrosion of, 303 Τ.
Machine screws, 139-140 man
Magnesium and magnesium alloys, 43-44 Nickel steels , 37
Nitrogen trailer, 357-359 ac
Magnesium , corrosion of, 302
Nonferrous aircraft metals, 37-44 airco
Main landing gear, 67-69
Maintenance Instructions Manuals, 18-20 Nonmetallic materials, 52-56 fl
Manual type publications, 16-24 NT - 4 tow bar, 335-337 ge
MECH, 27 Numerical Sequence List, 12-13 IE
Mechanical cleaning materials, 289-290 Nuts, aircraft. (See Fasteners ) M
P
Mechanical lock rivets, 122, 189-194 Outfitting Lists, 17
Metal cutting equipment, 100-102 ST
shears : W
Packaging and barrier materials, 298 safe
hand bench >, 102 Paint removal, 307 sup
384
INDEX
Painting, aircraft, 316-328 technical information file of support equip

Paints, aircraft, 317-319 ment , 23-24
Patches: numbering system , 16, 25
flush , 160-163 letter material , 25
lap , 159-160 manuals, 16
Penetrant inspection , 45-52 security of, 15-16
Periodic Maintenance Requirements Manual, 20 Pulleys, 152-153
Personnel Qualification Standards (PQS ) , 7-8 Push-pull rods, 154
Plane director, 333-334 Pylon , 75-76
Plastic enclosures, transparent, 52-55 , 227-232
installment of panels , 230-232 Qualifications Manual , 4-7
removing scratches , 228-230 Quick disconnects , 149
surface cleaning, 227-228
Plastics : Rapid Action Change ( RAC ) System, 16
reinforced , 55-56 , 165-173 Rating structure , 1
transparent, 52-55 Reading List, iv
Pneumatic system servicing, 355 , 357-361
>
Record of Practical Factors, 8
Polyurethane finishes, aircraft, 318-319 Refueling aircraft, 347-351
Powerplants , mobile , 372-375 Repair material, 157
Preservation materials, 296-297 Repair, trailing edge , 177
Preservation of aircraft, 295-298 Rig pins, 99
Presetting , flareless -tube fittings, 267-269 Rigid tubing, 259-262
Pressure fueling, 349-351 Rivet cutters, rotary , 86-87
>
Pressure oiling , 352-354 Rivet head shaver, 94

Protective covers , 293-295 , 340-341 Rivet installation :
Publications , aeronautic , 12-27 blind , 188
Index , 12-16 friction lock tools , 188
Aircraft Application List, 14 Rivet removal, 186-187
Directives Applications List, 14 Rivet set, 87
Equipment and Subject Availability List , Riveters, pneumatic, 94-97
14 Riveting:
Equipment Applicability List, 13-14 flush , 180
Numerical Sequence List , 12-13 procedure , 177-178 , 185-186
>
Updating, 15 Rivets :
letter material, 24-27 blind , 121-123
Bulletins, 24-26 pull-through , 122
Changes, 24-26 Rivnut, 122-123
Instructions and Notices , 26-27 ' self- plugging, 122
Technical Directives , 24-26 High -Shear, 120-121
manuals, 16-24 > identification , 121
accessories, 22 solid , 119-120
aircraft, 17-22 composition , 120
flight manual (NATOPS), 17 identification code , 119-120
general aircraft manuals, 22 Rivnut, 122-123
IPB , 21 installation of, 194-197
MIM , 18-20 Rotary machine, 105-107
PMRM , 20 beading , 105-106
structural repair, 20 burring, 106-107
weight and balance, 21-22 crimping, 106
safety precautions, 23 turning, 106
support equipment , 23-24 wiring, 106
385
Rotary rudder blades , 76 Tail gear, 69-71 Tow bars, 3

Rotary rudder head , 76 Tail skag, 71-72 Towing air
Rotor head , 75 Taps and dies, 98 Trailer, air)
Rotor wing, 74-75 Taxi signalman , 333-334 Trailing edg
Rubber hose , flexible , 274-279 Taxi signals , 334 Trim tabs,
TD- 1 tiedown , 337-338 Tube assem
Technical Directives, 24-26 brazed ,
Safety precautions: Technical Information File of Ground Support flared, 2
armed aircraft, 345 Equipment , 23-24 flareless
engine noise, 341-342 Teflon hose , flexible , 279-281 oxygen
exhaust area hazards, 341 Tensiometer , 90 , 93 Tube benē
flight deck, 345 Theory of flight ( rotary wing), 76-84 hand be
foreign object damage , 346 Threaded fasteners, (See Fasteners.) mechar
fueling, 347-349 Throw boards, 99-100
intake duct hazards, 342 Tiedown , aircraft: Tube cutt
overheated brakes, 342-345 afloat, 337-338 Tube flar
seat ejection mechanisms, 342 ashore, 338-340 Tubes, in
Safety Precautions Manual , 23 Tire inflation , 252-253 Tubing ,
Safety wire , 141-142 Tires , aircraft, 238-256 layout
Sandwich construction , (honeycomb and balsa Titanium and titanium alloys, 42 remov
wood core ), 56 , 173-176 Titanium , corrosion of, 303 Tubing,
Screws ( See Fasteners. ) Tools : fittin :
Sealants , 328-329 , 331-332 custody , 85-86 sizes
Sealants , application of, 329-331 inventory , 86
Seams, sheet metal , 113-114 procurement, 85
Sectors and quadrants, 153-154 Tools :
Self -tapping screws, 140 cutting tools , 90-91
Setscrews, 140 extractors, screw and bolt , 98
Shears, 101-102 miscellaneous tools , 90 , 92
>
hand bench , 102 rig pins, 99

squaring, 101 riveting tools, 86-89
throatless, 101-102 bucking bars, 87-88
unishear, 102 hole finder, 88
Skin repairs, 157 , 159-165 rivet cutters , rotary , 86-87
Skin replacement , 163-165 riveters, pneumatic :
Slats , 66 corner riveters , 96
Slip -roll forming machine , 102-105 fast hitting, 96
Solvent-emulsion cleaning, 289 gun selection , 96-97
>
Solvents, 288-289 one shot , 96

Spanner wrenches , 90 slow hitting , 96
Speed brakes, 66 squeeze , 96
Spoilers , 65-66 rivet head shaver, 94
Spring tabs , 65 rivet set, 87
Stabilizers, 62-63 taps and dies , 98
Stainless steels, 37 throw boards, 99-100
Stress corrosion , 305 wrenches :
Striking tools , 89 spanner, 90
Structural Repair Manual , 20 strap , 98
Support Equipment Manuals, 23 torque, 90
Surface control locks, 338 Torque Wrenches, 90-93
Surface maintenance, 287-293 Touchup painting, 316-317
386
INDEX
Tow bars, 335-337 Turnbuckles, 148-149 , 221

Towing aircraft, 334-335 Turnlock fasteners. (See Fasteners .)
Trailer, air/nitrogen , 357-359 Turrent punch, 102
Trailing edge repair, 177
Trim tabs, 64-65
Unishear, 102
Tube assemblies, installation of: Universal tow bar, 335-337
brazed , 272-274
flared, 269-270 Vacu-Blast dry honer, 310-314
flareless, 270-272 V -band coupling, 144
oxygen system , 274
Tube bending : Walking beams, 154
hand bender, 264 Washers , 136 , 138
mechanical bender, 264 Water emulsion cleaning, 291 , 293
Water rinse cleaning, 291
Tube cutting, 263-264 Weight and Balance Data, Manual, 21-22
Tube flaring, 264-265 , 267 Wheels, landing, 235-238
Tubes , inner, 256 , 257 balancing, 238
Tubing, damaged : demountable flange type, 236
layout of lines , 263 divided (split ) type, 235-236
removal and replacement, 262-263 maintenance, 238
Tubing, rigid : Wing, rotary , 74-75
fittings, 260-262 Wings, 59-62
sizes, 260 Wrought alloys (aluminum), 38
387 $ U. S. GOVERNMENT PRINTING OFFICE : 1974 0 - 542-195 ( 17-2)

1
1
1
UNIVERSITY OF MINNESOTA
3 1951 DO3 548226 E

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STRUCTURAL MECHANIC S 3 & 2

It is upon the maintenance of this control that our country's glorious

WE SERVE WITH HONOR

At home or on distant stations we serve with pride , confident in the respect

THE FUTURE OF THE NAVY

1. Aviation Structural Mechanic S rating 1

United States Armed Forces Institute ( USAFI ) courses for additional

C 151 General Mathematics I

* Members of the United States Armed Forces Reserve components , when

AVIATION STRUCTURAL MECHANICS RATING

ADJC ADRC AMSC

ADJI ADRI АМНІ AMSI

ADJ 3 ADR3 AMS3

AIRMAN AME " A"

LDO INPUT ZONE

Maintenanceman , Warrant Officer ( W-4) , or to LEADERSHIP

FACTORS check completed for E-3 and all PO advancements .

Specified ratings must complete

Required for 3-3 and all PO advancements Correspondence

course has already been completed . See reading . See

Figure 1-2.-Active duty advancement requirements.

* El to E263to E3E4to E4to E5 to E6 to

36 mos . 36 mos. 24 mos .

PERFORMANCE Specified ratings must complete applicable

DRILL Satisfactory participation as a member of a drill unit

* Recommendation by commanding officer required for all advancements.

Figure 1-3 . - Inactive duty advancement requirements.

SOURCES OF INFORMATION handtool operations that are performed by

and related equipment according to model , type , DIRECTIVES APPLICATION LIST

UPDATING THE INDEX and filed . A knowledge of the numbering sys

Prefix Part I Part II Part III

A NavAirSysCom originated publication

and are later incorporated as regular revisions. Flight Control Systems.

The Maintenance Instructions Manuals NOTE : The different aircraft manufacturers

not provided in other manuals. Included are servicing the aircraft.

Section It NAVAIR01-75PAA 2-2.3

Materials List Elevator Sling Assembly 551241-1

Cotter Pin ( 2 ) MS24665-300 Manpower Requirements

An Amendment is a document comprised of Photographic.

This section is devoted primarily to the terms

Brittleness members and parts are so designed that the

Elasticity Conductivity is the property which enables a

Contraction and Expansion apart . Tensile strength is measured in pounds per

than 6 x 6 inches. Rectangular sections which Cold -Working

HOT ROLLED DRAWING JAW

STEEL DIE 25 % TO 45 % REDUCTION

MANDREL ROD DIE TUBING DRAW HEAD

DIE HEAD JAWS

Type of steel Classification

common applications are in the fabrication of monel and babbitt .

strength range of structural steel. Table 3-2 . - Designations for aluminum

condition . the repair of wingtips and tanks .

Designation Condition indicated Example

-F... As fabricated 3003 - F

-O Fully annealed .. 6061-0

-W Unstable following solution heat

-H Strain hardened ( cold worked )

-HI , Strain hardened only 3003 - H12