Airraft Hardwares
Airraft Hardwares
Airraft Hardwares
HARDWARES
BOLTS
NUTS
WASHERS
What is hardware?
Aircraft Fastener
Standardization and
Selection
AN = Air Force/Navy
NAS = National Aerospace Standards
MS = Military Standards
BOLTS
BOLTS
BOLTS vs SCREWS
PARTS OF A BOLT
TYPES OF BOLTS
GENERAL PURPOSE BOLTS
AIRCRAFT BOLTS
( Threaded fasteners)
AN BOLT HEAD
IDENTIFICATION
GENERAL PURPOSE - CROSS OR
ASTERISK
EX. AN4-8A
EX. AN4-8
AIRCRAFT BOLTS
( Threaded fasteners)
GENERAL PURPOSE BOLTS
The AN 73 - AN 81 (MS20073-MS20074) drilled
head bolt is similar to the standard hex bolt,
but has a deeper head that is drilled to receive
wire for safetying. The AN3-AN20 and AN73AN81 series bolts are interchangeable.
AIRCRAFT BOLTS
( Threaded fasteners)
CLOSE TOLERANCE BOLTS
This type of bolt is machined more accurately
than the general purpose bolt. They can be
Hex headed - (AN173-AN186) or have a
Countersunk head- (NAS80-NAS86) they are
used in applications where a tight drive fit is
required (the bolt will only move into position
only when struck with a 12-14 ounce hammer)
AIRCRAFT BOLTS
( Threaded fasteners)
Types of Bolts
CLEVIS BOLT
AIRCRAFT BOLTS
( Threaded fasteners)
HEAD MARKINGS
CLOSE TOLERANCE
(STEEL OR ALUMINUM
ALLOY)
ALUMINUM ALLOY
(62,000 P.S.I.)
CORROSION RESISTANT
STEEL (125,000 P.S.I.)
AIRCRAFT BOLTS
( Threaded fasteners)
BOLT DESIGNATION
AN4-H8A
AIRCRAFT BOLTS
( Threaded fasteners)
THREAD DESIGNATION
Threads are designated by the number of times
the incline (threads) rotates around a 1 inch
length of given diameter bolt or screw.
EX. 4-28 thread indicates that a dia. Bolt
has 28 threads in 1 of its thread length.
AIRCRAFT BOLTS
( Threaded fasteners)
THREAD designation
Threads are designated by the Class fit
(tolerance allowed in manufacturing).
Class 1 Loose fit (Easily turned by the fingers)
Class 2 Free fit (Aircraft Screws)
Class 3 Medium fit (Aircraft Bolts)
Class 4 Close fit (Requires a wrench to turn the nut onto
a bolt)
Bolt Application
Clearance Fit in this assembly there is a space between the two parts. The
shaft is always smaller than the part it fits into.
Interference Fit in this assembly there is no space between the parts. The
shaft is always larger than the part it fits into. This means that force is
required to assemble the parts.
Transition Fit this is a range of fits which can be either clearance or
interference. The shaft can be larger or smaller than the part it fits into.
AIRCRAFT BOLTS
( Threaded fasteners)
NUTS
NUTS
TYPES OF NUTS
CASTLE NUTS
SELF-LOCKING NUTS
AIRCRAFT NUTS
Castle Nuts
AN310 and AN320 castle nuts are the most
commonly used. Castle nuts are fabricated
from steel and are cadmium plated. Corrosion
resistant castle nuts are also manufactured
(AN310C and AC320C - remember, when you
encounter a "C" it will designate stainless).
Castle nuts are used with drilled shank bolts,
clevis bolts and eye bolts. The slots in the nut
accommodate a cotter pin for safetying
purposes.
AIRCRAFT NUTS
Castle Nuts
AN310 Cad
Plated
AN310 Steel
AIRCRAFT NUTS
Self-Locking Nuts
Self-locking nuts, as the name implies, do not need a
locking device.
The most common method of locking is derived from
a fiber insert.
This insert has a smaller diameter than the nut itself
so that when a bolt enters the nut it taps into the
fiber insert producing a locking action.
The designation of these nuts is AN365 and AN364.
AIRCRAFT NUTS
Metal Locking Nut
AIRCRAFT NUTS
Plain Aircraft Nuts
Plain nuts require a locking device such as a
check nut or lockwasher. They are not widely
used in most aircraft. AN315 is the
designation used for a plain hex nut. These
nuts are also manufactured with a right hand
thread and a left hand thread. The check nut
used to hold a plain nut in place is an AN316.
If a lockwasher is used a plain washer must
be under the lockwasher to prevent damage
to the surface.
AIRCRAFT NUTS
Other Aircraft Nuts
There are a number of other aircraft nuts
available. Wing nuts (AN350) are commonly
used on battery connections or hose clamps
where proper tightness can be obtained by
hand. Anchor nuts are widely used in areas
where it is difficult to access a nut.
Tinnerman nuts, instrument mounting nuts,
pal nuts, cap nuts, etc. are all examples of
other types that are used.
WASHERS
WASHERS
REFERENCES:
POWERPOINT PRESENTION:
AC 43-13 1.B
(Chapter 07 Aircraft Hardware,
Control Cables and Turnbuckles)
Section 3 [7-34] [7-100]
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