TM 55-6610-293-40

DEPARTMENT OF THE ARMY TECHNICAL MANUAL

GS MAINTENANCE MANUAL

ATTITUDE INDICATOR
MODEL NUMBER 4005AB
PART NUMBER 141400-01-01

HEADQUARTERS, DEPARTMENT OF THE ARMY

SEPTEMBER 1967
 WARNING
PRECAUTIONARY DATA
Personnel performing instructions involving operations, procedures, and practices which
are included or implied in this manual shall observe the following instructions. Disre-
gardof these warnings and precautionary information can cause serious injury, death,
or an aborted mission.

CONNECTION OF POWER TO TEST SETUPS.

To prevent electrical shock when connecting the test setups to power sources, be certain power is shut off.

USE OF METHYL-ETHYL-KETONE AND FREON PCA.

When using methyl-ethyl-ketone and Freon PCA, wear rubber gloves to prevent prolonged contact with skin.
Methyl-ethyl-ketone is flammable. Avoid using near flame or other igniting source.
 TM 55-6610-293-40
C2

CHANGE HEADQUARTERS
DEPARCTMENT OF THE ARMY
No. 2 WASHINGTON, D. C., 8 March 1971

GS Maintenance Manual
Including Repair Parts and Special Tools List

ATTITUDE INDICATOR

MODEL NUMBER 4005AB

PART NUMBER 141400-01-01

TM 55-6610-293-40, 7 September 1967, is changed as follows:

Page 23, paragraph 18d(2). Change second sentence to read, “Indicator

shall indicate 8 degrees to 20 degrees left roll.”

By Order of the Secretary of the Army:

W. C. WESTMORELAND,
General, UnitedStates Army,
Official: Chief of Staff.
KENNETH G. WICKHAM,
Major General, UnitedStates Army,
The Adjutant General.

DISTRIBUTION:
To be distributed in accordance with DA Form 12-31 (qty rqr blocks no.
337, 344, 35, and 354, cumulative for all blocks) requirements for Direct
and General Support Maintenance Instructions for UH-1A, UH-1B, UH-1C, UH-1D
and 1H Aircraft.

1
11
 TM 55-6610-293-40

TECHNICAL MANUAL HEADQUARTERS

DEPARTMENT OF THE ARMY
TM 55-6610-293-40 W A S H I N G T O N , D. C., 7 September 1967

ATTITUDE INDICATOR
MODEL NUMBER 4005AB
PART NUMBER 141400-01-01

S ECTION I. INTRODUCTION Paragraph Page

General --------------------------------------------------------- 1 2

Purpose ---------------------------------------------------------------------- 2 3

Equipment Records -------------------------------------------------------- 3 3

Description ------------------------------------------------------------ 4 3

Leading Particulars ---------------------------------------------------- 5 3

II. TEST EQUIPMENT, SPECIAL TOOLS, AND MATERIALS

Test Equipment ----------------------------------------- 6 3

Special Tools --------------------------------------------- 7 3

Consumable Materials Required ------------------------------------------ 8 3

III. OVERHAUL INSTRUCTIONS

Introduction ------------------------------------------------------------ 9 6

Disassembly --------------------------------------------------------------- 10 6

Cleaning ----------------------------------------------------------- 11 12

Inspection ------------------------------------------------------------- 12 14

Repair or Replacement ------------------------------------------------ 13 17

Lubrication ---------------------------------------------------------- 14 17

Reassembly and Testing of Assemblies ------------------------------- 15 18

Final Assembly --------------------------------------------------------- 16 19

IV. FINAL TEST PROCEDURES

Introduction ----------------------------------------------------------- 17 22

Testing -------------------------------------------------------------------- 18 22

Trouble Shooting ------------------------------------------------------ 1 9 25

A PPENDIX A . REFERENCES ---------------------------------------------------------------------- 28

1
 TM 55-6610-293-40

SECTION I

INTRODUCTION

1. General. b. Reporting of Improvements. Direct re-

a. This technical manual comprises overhaul porting of errors, omissions, and recommenda-
instructions for Attitude Indicator, Model Num- tions for improving this manual by the
ber 4005AB, Part Number 141400-01-01 (see individual user is authorized and encouraged.
figure 1), manufactured by Lear Siegler/Inc, DA Form 2028 will be used for reporting these
Federal Code Number 35351, Grand Rapids, improvements. DA Form 2028 will be completed
Michigan. Sections I through IV of this by the individual using this manual and for-
technical manual contain instructions for this warded directly to: Commanding General,
model. Overhaul instructions for additional U. S. Army Aviation Materiel Command,
models will be provided in Section V by the use ATTN: AMSAV-M, P. O. Box 209, St. Louis,
of difference data sheets. Missouri, 63166.

Figure 1. Attitude Indicator, Part Number 141400-01-01

2
 TM 55-6610-293-40

Table 1. Leading Particulars

2. Purpose.
Power Requirements
The Attitude Indicator (Indicator) is an Indicator-------------------------------------------115 volts, 400 cps
electro-mechanical unit which provides aircraft Lighting ---------------------------------------28 volts, ac or dc
roll and pitch attitude information for the pilot. Input and Output Signals
The Indicator pictorially displays attitude Input--------------------Obtained from vertical gyroscope
relative to straight and level flight. Signals for reference which provides pitch and
operation are received from a vertical gyroscope. roll information
Output------------------Visual readout in pitch and roll
Dimensions (maximum overall)
3. Equipment Records. Height-----------------------------------------------5.260 inches
Width ----------------------------------------------5.010 inches
The Army equipment record system and Length------------------------------------------------7.386 inches
procedures established in TM38–750 apply to Electrical Connectors---------------Connector, part number
the equipment. The applicable forms as required 142916–01 mates with connector,
by TM38–750 shall be used. Military Standard MS24009
Weight---------------------------------------------------5-1/2 pounds
Operating Controls
4. Description. Pitch Trim Knob-----------------Located at lower right
The Indicator is hermetically sealed and is hand corner of the front of Indicator; it allows
comprised mainly of pitch and roll servo loop pitch indication to be centered when the aircraft is
components, a terminal board, and internal trimmed within approximately 8 degrees dive and
16 degrees climb.
lighting assemblies.
Roll Trim Knob---------------------Located at upper right
hand corner of the front of Indicator; it allows roll
indication to be centered when the aircraft is
5. Leading Particulars. trimmed with approximately 8 to 20 degrees of
Refer to table 1. level in either right or left roll.

SECTION II

TEST EQUIPMENT, SPECIAL TOOLS, AND MATERIALS

6. Test Equipment. 8. Consumable Materials Required.

The test equipment required for overhaul is The consumable materials used during over-
listed in table 2. haul are listed in table 3.
7. Special Tools.
No special tools are required for overhaul.

Table 2. Test Equipment Required

Applicable Maintenance Level

Direct Or
Item Model No. And Technical General
No. Manufacturer Nomenclature Description Organization Support Depot

1 *Model BF-60 R/C bridge Used to check re- X

Cornell-Dubilier sisters and capaci-
Electric Corporation, tors.
Newark, New Jersey
(14655)
* Any equivalent may be used.

3
TM 55-6610-293-40
Table 2. Test Equipment Required--Continued

Applicable Maintenance Level

Direct Or
Item Model No. And Technical General
No. Manufacturer Nomenclature Description Organization Support Depot

2 *R510-1A Test transmitter Standard synchro x

Kearfott Divsion of General test trasmitter; for
Precision, Incorporated, generating synchro
Little Falls, New Jersey error signals (2 re-
(88818) quired).
3 *PM-6B Multimeter For dc resistance X
Bruno-New York measurements.
Industries Corporation,
New York, New York
(95325)
4 *Model 300 Ac vacuum tube For ac voltage X
Ballantine Laboratories, voltmeter measurements.
Incorporated, Boonton,
New Jersey (06635)
5 *Model 304H Oscilloscope For phase X
Allen B. Du Mont measurements.
Laboratories, Incorporated,
Clifton, New Jersey (82170)

* Any equivalent may be used.

Table 3. Consumable Materials Required

Applicable Maintenance Level

Direct or
Item Type or Government General
No. Material Grade Specification Organization Support Depot

1 Paint Remover ---- Military Specification X

MIL-R-8633A
2 Tetrachloroethylene ---- Federal Specification X
O-T-236
3 Methyl-ethyl-ketone ---- Federal Specification X
TT-M-261
4 Lens tissue paper IV or V Federal Specification X
UU-P-313
5 Solder Sn60 Federal Specification X
QQ-S-671
6 Masking tape ---- Federal Specification X
UU-T-106
7 Wash primer ---- Military Specification X
MIL-C-15328
8 Black enamel ---- Military Specification X
MIL-E-5556
9 Xylene thinner ---- Federal Specification X
TT-X-916

4
 TM 55-6610-293-40

Table 3. Consumable Materials Required--Continued

Applicable Maintenance Level

Direct or
Item Type or Government General
No. Material Grade Specification Organization Support Depot

10 Lubricating oil ---- Military Specification X

MIL-L-6085A
11 Grease ---- Military Specification X
MIL-G-G23827
12 Adhesive H Military Specification X
MIL-S-22473
13 Hysol R8-2038 Base Resin, ---- ---- X
manufactured by Hysol
Corporation, Orlean, New
York (04347), or equivalent
14 H2-3475 Hardener, manu- ---- ---- X
factured by Hysol
Corporation, Orlean, New
York (04347), or equivalent
15 Cab-O-Sil Filler, manu- M-5 ---- X
factured by Godfrey L.
Cabot, Incorporated, Boston,
Massachusetts (80798), or
equivalent
16 Freon PCA, manufactured ---- X
by E. I. du Pent, de
Nemours and Company,
Incorporated, Chicago,
Illinois (18873), or
equivalent
17 Stur-D-Lace HL Soft Finish ---- ---- X
Lacing Tape, manufactured
by Gudebrod Brothers Silk
Company, Incorporated, New
York, New York (01670) or
equivalent
---- X
18 Wornow Ink Series “M”
White Epoxy Coding Ink,
manufactured by Wornow
Process Paint Company,
Los Angeles, California
(79439) or equivalent
19 Tetrafluoroethylene Ad- ---- ---- x
hesive Tape, manufactured
by Chicago Gasket Company,
Chicago, Illinois (06644),
or equivalent
20 Epon Adhesive VII Plus ---- ---- x
Curing Agent A, manufac-
tured by Shell Chemical
Corporation, New York, New
York (86961), or
equivalent
5
TM 55-6610-293-40

Table 3. Consumable Materials Required-Continued

Applicable Maintenance Level

Direct or
Item Type or Government General
No. Material Grade Specification Organization Support Depot

21 EC847 Adhesive, manu- ---- ---- X

factured by Minnesota
Mining and Manufacturing
Company, Detroit, Michigan
(88525) or equivalent

SECTION III

OVERHAUL INSTRUCTIONS

9. Introduction. (2) Remove paint as follows: mask off

The following procedures outline step by step bezel assembly (1) and connector (23).
overhaul instructions for the Indicator. The Remove paint from Indicator using
extent of overhaul will seldom require that each paint remover, Military Specification
step be performed, thus only those steps re- MIL-R-8633A. If complete paint re-
quired to effect the necessary repair need be moval is not required remove paint
performed. around sealing strip (20) using paint
remover.
10. Disassembly.
(3) Snip off end of evacuating vent (24).
a. Attitude Indicator, Part Number 141400-
01-01. (4) Use a heavy duty soldering iron (250
(1) If it is required that identification watts ) to remove excess solder around
plate (22, figure 2) be replaced, pro- sealing strip (20 ). Grip sealing strip
ceed as follows: Record the infor- with long nose pliers and carefully
mation contained on plate, as it will be pull off. Discard sealing strip.
required during reassembly. Insert a Note. At this time Indicator should be
knife or sharp-edged tool under one removed to clean room conforming to Fed-
corner of plate and peel off. eral Standard No. 209, class 100,000.

Legend for figure 2

1. Bezel Assembly 18. Bearing 35. Bracket

2. Stud 19. Transformer (T1) 36. Motor-Tachometer Generator
3. Yoke and Sphere Assembly 20. Sealing Strip (MG2)
4. Gear Cluster 21. Cover 37. Screw
5. Gear Cluster 22. Identification Plate 38. Clamp
6. Plate Assembly 23. Connector (J1) 39. Screw
7. Screw 24. Vent 40. Screw
8. Stud 25. Latch and Bracket Assembly 41. Washer
9. Indicator Subassembly (TB2) 26. Printed Wiring 42. Stud
10. Washer 27. S c r e w 43. Screw
11. Screw 28. Terminal (E2) 44. Clamp
12. Screw 29. Clamp 45. Housing and Stator Assembly
13. Washer 30. Ring 46. (B2B)
14. Brush Assembly (E1) 31. Shim, 0.025 inches 47. Bearing
15. Stud 32. Shim, 0.010 inches 48. Shim, 0.002 inches
16. Washer 33. Shim, 0.005 inches 49. Shim, 0.010 inches
17. Screw 34. Shim, 0.0015 inches 50. Ring
6
 TM 55-6610-293-40

Figure 2.

7
TM 55-6610-293-40

Figure 3.

8
 TM 55-6610-293-40

1. Knob 12. Light Assembly (DS1)

2. Scale Dial 13. Rubber Pad
3. Screw 14. Screw
4. Knob 15. Miniature Airplane
5. Scale Dial 16. Scale Dial
6. Resistor, 4k ± 10%, 1w (R14) 17. Rubber Pad
7. Bezel Assembly 18. Power-Off Warning Indicator
8. Resistor, 4k ± 10%, 1W (R17) (M1)
9. Light Shield 19. Screw
10. Light Wedge 20. Clamp
11. Rubber Pad

Figure 3. Bezel Assembly—Continued

(5) Slide cover (21) off Indicator. (13) Remove ring (30), shims (31, 32, 33,
and 34), and bearing (18). Slide yoke
Caution: Printed wiring is attached
and sphere assembly (3) away from
between internal assembly and con-
plate assembly (6). Note number of
nector in cover. Care must be observed
shims (31, 32, 33, and 34) to aid, in
so printed wiring is not damaged.
reassembly.
(6) Do not remove printed wiring (26). (14) Remove bearing (46) from plate as-
(7) Remove screws (11, 39, and 40) and sembly (6). Remove screws (43),
washers (10 and 41). clamps (44), and housing and stator
(8) Remove screws (27) and terminal assembly (45) from plate assembly
(28). Remove transformer (19) and (6).
clamps (29 ). (15) Remove rings (49), shims (47 and 48),
and gear clusters (4 and 5) from plate
Note. Cut lacing cord as necessary to gain
access to or to remove components. Do not assembly (6).
remove wiring unless necessary to replace a b. Bezel Assembly.
component.
(1) Remove scale dial (16, figure 3).
(9) Remove screws (17) and washers (16). (2) Remove screws (14), and miniature
Slide bracket (35) and brush assembly airplane (15).
(14) away from ring assembly (23, (3) Remove screws (19) and clamps (20).
figure 4) being careful not to bend Slide power-off warning indicator
brushes. (18) away from scale dial (16).
(10) Carefully remove indicator subassem- (4) Remove light assembly (12 ) and rub-
bly (9, figure 2), ber pad (11 ) from bezel assembly.
(11) Remove screws (37) and clamps (38). (5) Remove light wedge (10) and light
Remove motor-tachometer generator shield (9) from bezel assembly.
(36). (6) Do not remove knobs (1 and 4) unless
(12) Remove screws (7). Slide yoke and knobs or scale dials (2 and 5) are to be
sphere assembly (3) and plate assem- replaced.
bly (6) away from bezel assembly (7) Do not attempt to remove resistors (6
(1). Remove studs (2) from bezel and 8).
assembly (1).
c. Yoke and Sphere Assembly.
Caution: Do not break wires leading (1) Remove bank pointer (42, figure 4) by
to bezel assembly. Detail parts of breaking attaching epoxy seal and
bezel assembly are loose. Use care not sliding bank pointer from mechanism
to damage parts. mask (41 ).

9
TM 55-6610-293-40

Figure 4.

10
 TM 55-6610-293-40

1. Capacitor, 1 uf ± 10%, 200 22. Spacer

Vdcw (C1) 23. Ring Assembly (SR1)
2. Screw 24. Screw
3. Loop Clamp 25. Sleeve Bearing
4. Printed Wiring Board (TB1) 26. Screw
5. Post 27. Clamping Plate
6. Ring 28. Indicator Sphere
7. Shim, 0.010 inches thick 29. Shaft Collar
8. Collar 30. Setscrew
9. Setscrew 31. Mounting Plate
10. Gear Cluster 32. Synchro (B1)
11. Gear Set 33. Screw
12. Spring 34. Synchro Clamp
13. Gear Cluster 35. Screw
14. Shim, 0.002 inches thick 36. Motor-Tachometer Generator
15. Screw (MG1)
16. Counterbalance Assembly 37. Screw
17. Gimbal 38. Synchro Clamp
18. Screw 39. Pitch Plate Assembly
19. Gear Set 40. Screw
20. Spring 41. Mechanism Mask
21. Rotor and Shaft Assembly 42. Bank Pointer
(B2A)

Figure. 4. Yoke and Sphere Assembly—Continued

(2) Remove screws (40). Slide mechanism (26) and clamping plate (27). Slide
mask (41) from yoke and sphere as- indicator sphere (28) away from
sembly. internal assembly.
(3) Remove epoxy adhesive attaching (8) Remove screws (35). Separate capaci-
counterbalance assembly (16) to gim- tor (1), printed wiring board (4), and
bal (17) by heating adhesive with and posts (5) as an assembly from
soldering iron and scraping loose. pitch plate assembly (39).
(4) Remove screws (24) and sleeve bear- (9) Remove rings (6), shims (7), gear
ing (25). clusters (10 and 13), and shims (14)
(5) Hold indicator sphere (28) and re- from their respective shafts.
move screws (15). Carefully slide (10) Loosen setscrews (9), remove collar
indicator sphere forward from gimbal (8), and slide gear set (11) away from
(17). pitch plate assembly (39).
Caution: Do not break wires leading (11) Loosen setscrews (30) and remove
from slip rings to assembly in indicator shaft collar (29), Slide mounting
sphere. plate (31 ) from shaft of synchro (32).
(12) Remove screws (33), synchro clamp
(6) Remove screws (18). Remove gear set (34), and synchro (32) from pitch
(19), rotor and shaft assembly (21), plate assembly (39).
spacer (22), and ring assembly (23).
Do not attempt to separate ring as- (13) Remove screw (37), synchro clamp
sembly (23) from rotor and shaft (38), and motor tachometer-generator
assembly (21) . (36) from plate assembly (39).
(7) Hold assembly located inside of indi- d. Indicator Subassembly, Part Number
cator sphere (28), and remove screws 143332-01-01. (See figures 5 and 6.)

11
TM 55-6610-293-40

1. Resistor, - 240 ohms ± 5%, 2 W 10. Resistor, 4.3k ± 5%, 0.25w 19. Resistor, 5.11k ± 1%, 0.25w
(R6) (R27)
2. Resistor, 15k ± 5%, 0.25w 11. Resistor, 1.2k ± 5%, 0.25w 20. Resistor, 10k ± 1%, 0.25w
(R3) (R21) (R2)
3. Resistor, 20k ± 5%, 0.25 w 12. Resistor, 2.5k ± 5%, 0.25w 21. Resistor, 5.11k ± 1%, 0.25w
, :.
(R28) (R18) (R1)
4. Resistor, 147 ohms ± 1%, 13. Resistor, 1.8k ± 5%, 0.5w 22. Resistor, 10k ± 1%, 0.25w
0.25 w (R29) (R26)
5. Resistor 267k ± 1%, 0.25w 14. Resistor, 3.3k ± 5%, 0.25w 23. Resistor, 10k ± 1%, 0.25w
(R20)
6. Resistor, 13k ± 1%, 0.25w 15. Resistor, 20k ± 1% 0.25w 24. Resistor, 3.9k ± 1%, 0.25w
(R22) (R25) (R4)
7. Resistor 10k ± 1%, 0.25w 16. Resistor, 2.43 ± 1%, 0.25w Resistor, 3k ± 5%, 0.5w (R23)
(R5) 25.
17. Resistor 20k ± 1%, 0.25w 26. Resistor 62 ohms ± 5%, 1 W
8. Resistor, 2.7k ± 5%, 1 W (R16) (R10)
9. Resistor; 267k ± 1%, 0.25w 18. Resistor, 5.11k ± 1%, 0.25w 27. Resistor, 200 ohms ± 5 %,
(R8) (R11) 0.25w (R13)

Figure 5. Restitor Arrangement for Indicator Subassembly, Part Number 143332-01-01

(1) No disassembly is required. If replace- (2) Residue from cement-spot locking of

ment of a part is necessary, refer to attaching parts should be removed by
paragraph 13d. careful scraping and then by washing
in or wiping with methyl-ethyl-ketone,
11. Cleaning. Federal Specification TT-M-261 de-
a. Attitude Indicator, Part Number 141400- pending on whether the part is free or
01-01. still is attached near electrical parts.
Note. All cleaned parts should be protected in clean Repeat the method using tetrachloro-
plastic boxes and bags until reassembled and should ethylene and dry with a vacuum source.
be handled in such a way that contamination from
handling is minimized, (3) Clean transformer (19), motor-ta
chometer generator (36), printed
(1) Clean bearings (18 and 46, figure 2) wiring (26) and cover (21 ) using a
gears (4 and 5), and their attaching soft brush and a vacuum source.
parts by washing in tetrachloro-
ethylene, Federal Specification O–T- (4) Clean plate assembly (6), housing and
236. stator assembfly (45), and bracket

12
 TM 55-6610-293-40

1. Capacitor, 47 uf ± 20%, 15 12.Diode Semiconductor Device 22. Diode Semiconductor Devic

Vdcw (C15) (CR8) (CR4)
2. Transistor Semiconductor De- 13. Capacitor, 15 uf ± 20%, 20 23. Diode Semiconductor Device
vice (Q5) Vdcw (C6) (CR3)
3. Capacitor, 47 uf ± 20% 6 14. Transistor Semiconductor 24. Capacitor, 47 uf ± 20%,
Vdcw (C5) Device (Q7) Vdcw (C3)
4. Transistor Semiconductor 15. Transistor Semiconductor 25. Capacitor, 0.01 uf ± 20%, 2
Device (Q6) Device (Q1) Vdcw (C7)
5. Heat Sink 16. Capacitor, 0.047 uf ± 1070, 50 26. Transistor Semiconductor
6. Capacitor, 47 uf ± 20%, 50 Vdcw (C8) Device (Q3)
Vdcw (C9) 17. Capacitor, 0.022 uf ± 10%, 50 27. Heat Sink
7. Diode, Semiconductor Device Vdcw (C4) 28. Diode Semiconductor Devic
(CR6) 18. Capacitor, 22 uf ± 20%, 50 (CR2)
8. Diode Semiconductor Device Vdcw (C13) 29. Transistor Semiconductor
(CR7) Device (Q2)
9. Transistor Semiconductor 19. Capacitor, 22 uf ± 20%, 50
Device (A4) Vdcw (C14) 30. Capacitor, 0.0022 uf ± 20%,
10. Capacitor, 15 uf ± 2%, 20 20. Capacitor, 25 uf –5 +30%,
Vdcw (C2) 125 Vdcw (C11) 31. Capacitor, 1.5 uf ± 20%, 2
11. Diode Semiconductor Device 21. Diode Semiconductor Device Vdcw (C10)
(CR1) (CR5) 32. Printed Wiring Board (C12
Figure 6. Capacitor and semiconductor~ Arrangement for Indicator Subassembly, Part
Number 14332-01-01-01

13
TM 55-6610-293-40

(35) using a clean, lint-free cloth (3) Clean indicator sphere (28) and face
dampened with tetrachloroethylene. of mechanism mask by using pressure-
sensitive masking tape to “dabot-off”
(5) Clean brush assembly (14) by allow-
any dirt or dust. ‘Avoid rubbing
ing a small amount of Freon PCA to
indicator sphere and face of mech-
flow over brushes. A suction source
nism mask to prevent shiny spots from
should be used to suck Freon PCA
appearing on paint.
through brushes.
(4) Clean remaining metallic parts and
b. Bezel Assembly. shafts of synchro (32) and motor-
(1) Residue from cement-spot locking of tachometer generator (36) with a
attaching parts should be removed by lint-free cloth dampened with tetra-
careful scraping and then by washing chloroethylene.
in or wiping with methyl-ethyl-ketone, (5) Residue from cement-spot locking of
depending on whether the part is free attaching parts should be removed by
or still is attached and near electrical careful scraping and then by washing
parts. Repeat the method using in or wiping with methyl-ethyl-ketone,
tetrachloroethylene and dry with a depending on whether the part is free
vacuum source. or still attached and near electrical
(2) Clean glass in bezel assembly (7, figure parts. Repeat the method using tetra-
chloroethylene and dry with a vacuum
3) and light wedge (10) with Freon
PCA and lens tissue paper, Federal source.
Specification UU-P-313, type IV or V. d. Indicator Subassembly, Part Number
143332-01-01.
(3) Clean face of scale dial (16) using
sticky side of pressure-sensitive paper (1) Clean solder connections on printed
masking tape, Federal Specification wiring board (32, figure 6) with a
UU-T-106 to “dab-off” any dirt or bristle brush moistened in tetrachloro-
dust. Avoid rubbing face of scale dial ethylene. Dry with a vacuum source.
(16), as rubbing may produce shiny (2) Remove any residue of cement-spot
spots on paint. locking by scraping and washing, first
with methyl-ethyl-ketone, then with
c. Yoke and Sphere Assembly. tetrachloroethylene. Dry with a vacu-
(1) Clean gear clusters (10 and 13, figure um source.
4) gear sets (11 and 19) and their 12. Inspection.
attaching parts by washing in tetra- a. Attitude Indicator, Part Number 141400-
chloroethylene. 01-01.
(2) Clean ring assembly (23 ) by using (1) Perform a visual and electrical inspec-
lens tissue paper dampened in Freon tion of Attitude Indicator as outlined
PCA. in tables 4 and 5.

Table 4. Visual Inspection Data For Attitude Indicator

Figure 2
Index No. Nomenclature Inspect For

4,5 Gear cluster Chipped teeth, burrs, and excessive wear.

23 Connector Bent or broken pins.
26 Printed wiring Breaks, cracks, and poor connections.
36 Motor-tachometer generator Defective teeth on shaft.

14
 TM 55-6610-293-40

Table 5. Electrical Inspection Data For Attitude Indicator

Figure 2 Procedure
Index No. Nomenclature Required Result

19 Transformer With multimeter, check dc re-

sistance between windings:
1 and 3 15 ohms maximum
2 and 3 4 ohms maximum
4 and 5 4 ohms maximum
6 and 8 3 ohms maximum
7 and 8 1.3 ohms maximum
8 and 9 1.3 ohms maximum
36 Motor-tachometer With multimeter, check dc re-
generator sistance between leads:
blue and orange 43 to 63 ohms
red and black 64 to 96 ohms
white and yellow 160 to 255 ohms
green and brown 254 to 384 ohms
45 Housing and stator Measure dc resistance between 370 ± 55.5 ohms
assembly leads with multimeter,

b. Bezel Assembly.
(1) Perform a visual and electrical inspec-
tion of bezel assembly as outlined in
tables 6 and 7.

Table 6. Visual Inspection Data For Bezel Assembly

Figure 3
Index No. Nomenclature Inspect For

7 Bezel assembly Scratches and nicks on glass.

10 Light wedge Scratches and nicks on glass.
Parts visible from front windows. Scratches or shiny spots on paint.

Table 7. Electrical Inspection Data For Bezel Assembly

Figure 3
Index No. Nomenclature Procedure Required Result

6 and 8 Variable resistor With multimeter measure re- 4k ± 10%

sistance between yellow and
green leads.
12 Light assembly Check continuity of each lamp Continuity indication.
with multimeter.

15
TM 55-6610-293-40

c. Yoke and Sphere Assembly.

(1) Perform a visual and electrical inspec-
tion of yoke and sphere assembly as
outlined in tables 8 and 9.

Table 8. Visual Inspection Data For Yoke And Sphere Assembly

Figure 4
Index No. Nomenclature Inspect For

28 Indicator sphere Cracks, defective paint, and shiny spots in paint.

10,11, Gears Chipped teeth, burrs, and excessive wear.
13,19
-- Screws or nuts Defective threads.

Table 9. Electrical Inspection Data For Yoke And Sphere Assembly

Figure 4
Index No. Nomenclature Procedure Required Result

21 Rotor and shaft Use multimeter to measure dc

assembly resistance between leads:
blue and black 109 ohms ± 1570
blue and yellow 109 ohms ± 15%
yellow and black 109 ohms ± 15%
(above values shall be within
2 ohms of each other)
32 Synchro Use multimeter to check dc re- 60 ohms ± 2%
sistance between all combina-
tions of blue, yellow, and black
leads.
36 Motor-tachometer Use multimeter to measure dc
generator resistance between leads:
red and black 64 to 96 ohms
white and yellow 160 to 255 ohms
green and brown 254 to 384 ohms

d. Indicator Subassembly, Part Number

143332-01-01.
(1) Perform a visual inspection of Indica-
tor Subassembly as outlined in table
10.

Table 10. Visual Inspection Data For Indicator Subassembly

Figure &
Index No. Nomenclature Inspect For

All connections ---- Breaks, cracks, and weak connections.

All connections ---- Burned condition.
32, Figure 6 Printed wiring board Breaks in wiring.

16
 TM 55-6610-293-40
0(2) Perform an electrical check of resistors bank pointer in position, apply epoxy
and capacitors suspected of being resin, and allow to cure.
defective using R/C bridge.
Note. Epoxy resin consists of 80 parts of
base resin (Hysol R8-2038), 20 parts
13. Repair And Replacement. hardener (HZ-3475), and 3 to 7 parts
a. Attitude Indicator, Part Number 141400- filler (Cab-O-Sil, Grade M-5). Mix thorough-
01-01. ly, apply to surfaces, and allow the cure
24-48 hours at room temperature.
(1) Solder a new vent (24, figure 2) into
cover (21 ) each time the Indicator is (3) To replace a defective capacitor (1
unsealed. Unsolder old vent and dis- unsolder and break loose capacity
card. Solder new vent, making sure from printed wiring board (4). (If
the solder joint is gas-tight. Use adhesive seal will not break loose, use
solder, Federal Specification QQ-S– a small amount of methyl-ethyl-ketone
571, comp Sn60. to soften adhesive. ) Scrape adhesive
(2) To replace a part connected to printed from printed wiring board. Apply
wiring (26 ), use a 37.5-watt soldering adhesive (EC847) between mating
iron and a vacuum source to remove surfaces of new capacitor and printed
solder connection on printed wiring. wiring board. Allow to dry for 1
Slide a flat tool under printed wiring minutes. Solder leads of capacitor in
and pry printed wiring away from place. Use solder, Federal Specification
component. QQ-S-571, composition Sn60.

Caution: Do not hold soldering iron d. Indicator Subassembly, Part Number

on printed wiring connections any 143332-01-01.
longer than necessary to make solder (1) To replace any detail part, unsolder
flow. and break loose the part from printed
wiring board (32, figure 6). Scrape
(3) If replacement of connector (23) or all old adhesive from printed wiring
latch and bracket assembly (25) is board. Apply adhesive (Epon Adhe
necessary, replace connector, latch and sive VII plus Curing Agent A) to mat
bracket assembly, and cover (21 ) as ing surfaces of detail part and printed
an assembly. wiring board. Allow to cure for 90
b. Bezel Assembly. minutes at 200°F (94°C). Solder
(1) If replacement of variable resistor (6 leads as necessary. Use solder, Federal
or 8, figure 3) is necessary, replace Specification QQ-S-571, composition
resistors (6 and 8) and bezel assembly Sn60.
(7) as an assembly. e. Replace all other parts found to be defec
c. Yoke and Sphere Assembly. tive during inspection procedures.
(1) If replacement of ring assembly (23, 14. Lubrication.
figure 4) is necessary, heat epoxy
adhesive as necessary to work ring a. Attitude Indicator, Part Number 141400
assembly free. Replace with a new 01-01.
ring assembly. (1) Lubricate bearings (18 and 46, figure
(2) To replace a defective bank pointer 2) with lubricating oil, Military Speci
(42), remove bank pointer by slightly fication MIL-L-6085A.
heating attaching epoxy adhesive with (2) Apply a film of grease, Military Speci
a soldering iron. Remove all traces of fication MIL-G-23827 to teeth and
epoxy adhesive by scraping. Clean bores of gears (4 and 5) and to teeth
surface with tetrachloroethylene, Fed- of shaft of motor-tachometer genera
eral Specification O-T-236. Place new tor (36).

17
TM 55-6610-293-40

b. Bezel Assembly. Note. The load combinations of R1-L1

(1) No lubrication is required. and R2-L2 each shall have an impedance
of 205 ohms ±2% +j245 ohms ±2%. (An
c. Yoke and Sphere Assembly. equivalent resistance can be obtained by
(1) Lubricate teeth and bores of gears (10, using red and black leads of motor-
11, 13, figure 4) with grease, Military tachometer generator (MG1 or MG2), part
number 142913-01.
Specification MIL-G-23837.
(2) Lubricate shaft of motor-tachometer (4) Connect 0,01 Vac ± 2%, 400 ± 4 cps
generator (36) and teeth of gear set between A(high) and B (low). This
(19) with grease, Military Specifica- input signal shall have a source imped-
tion MIL-G-23827. ance of 100 ohms maximum. Con-
d. Indicator Subassembly, Part Number nect ac vacuum tube voltmeter across
143332-01-01, load R1-L1. The voltage shall be 1.30
± 0.25 Vat. Measure phase shift
(1) No lubrication is required. across load R1-L1 with an oscillo-
15. Reassembly And Testing Of scope, The phase shift shall be 180
Assemblies. ± 10 degrees with respect to the in-
a. Indicator Subassembly, Part Number put. Disconnect 0.01 Vac signal.
143332-01-01. (5) Connect 0.10 Vac ± 2%, 400 ± 4 cps
(1) No reassembly of indicator subassem- between A(high) and B (low). This
bly is necessary. Refer to paragraph input signal shall have a maximum
13d(1). source impedance of 100 ohms. Con-
(2) Testing of indicator subassembly is nect ac vacuum tube voltmeter across
load R1-L1. The voltage shall be 6
accomplished by performing the fol-
lowing steps (3) through (11), Vac minimum. Measure phase shift
across load R1-L1 with oscilloscope.
(3) Connect test circuit as shown in figure The phase shift shall be 180 ± 10 de-
7. Do not connect load R2-L2 at this grees with respect to the input. Dis-
time. connect 0.10 Vac signal.
(6) Connect a jumper between A and B.
Measure voltage across load R1-L1
using ac vacuum tube voltmeter. The
voltage shall be less than 0.15 Vat.
Disconnect jumper.
(7) Disconnect power. Remove load R1-
L1 and connect load R2-L2 (see figure
7). Reapply power.
(8) Connect 0.07 Vac ± 2%, 400 ± 4 cps
between, C (high) and D (low). This
input signal shall have a maximum
source impedance of 100 ohms. Con-
nect ac vacuum tube voltmeter across
load R2-L2. The voltage shall be 5.0
± 0.5 Vat. Measure phase shift across
load R2-L2 with oscilloscope. The
phase shift shall be 180 ± 10 degrees
with respect to the input. Disconnect
0.07 Vac signal.
(9) Connect 0.185 Vac ± 276, 400 ± 4
Figure 7. Test Connections for Indicator Subassembly cps between C (high) and D (low).

18
 TM 55-6610-293-40

This input signal shall have a maxi- (8) Slide rotor and shaft assembly (21 )
mum source impedance of 100 ohms. into gear set (19 and 20) and attach
Connect ac vacuum tube voltmeter to gimbal (17) using screws (18).
across load R2-L2. The voltage shall
(9) Cement-lock screws (2, 15, 18, 33, 35,
be a minimum of 12 Vat. Measure
phase shift across load R2-L2 with an and 37) using adhesive, Military
Specification MIL-S-22473, Grade H.
oscilloscope. The phase shift shall be
180 ± 10 degrees with respect to the (10) Slide indicator sphere (28) into gimbal
input. Disconnect 0.185 Vac signal. (17), place counterbalance assembly
(10) Connect jumper between C and D. in position and start screws (15) (do
Measure voltage across load R2-L2 not tighten screws ). Loosen setscrews
using ac vacuum tube voltmeter. The (30), tighten screws (15), and then
voltage shall be less than 0.15 Vat. retighten setscrews (30).
(11) Remove power and all test connections. (11) Slide mechanism mask (41 ) into place
and attach with screws (40 ).
b. Yoke and Sphere Assembly.
(12) Cement-lock screws (15) and (40)
(1) Place motor-tachometer generator (36,
using adhesive, Military Specification
figure 4) onto pitch plate assembly
MIL-S-22473, Grade H.
(39) and attach with synchro clamps
(38) and screws (37). (13) No. testing of yoke and sphere assem-
(2) Place synchro (32) onto pitch plate bly is required.
assembly (39 ) and attach with syn- c. Bezel Assembly.
chro clamps (34) and screws (33).
(1) Reassemble scale dials (2 and 5, figure
(3) Slide mounting plate (31 ) onto syn-
3) and attach with screws (3).
chro (32) shaft and attach with collar
(29) and setscrews (30). (2) Position knobs (1 and 4) and tighten
Note. Tighten setscrews (30) only enough
setscrews in knobs.
to keep mounting plate (31) from sliding, (3) Slide light shield (9) and light wedge
(4) Slide gear set (11 and 12) into place (10) into bezel assembly (7).
on pitch plate assembly and attach (4) Position rubber pad (11 ) and light
with setscrews and collar (8 and 9). assembly (12).
(5) Slide shims (14), gears (10 and 13), (5) Slide power-off warning indicator (18)
and shims (7) onto pitch plate assem- into scale dial (16) and attach with
bly (39) and attach with rings (6). screws (19 ).
Check end play of gears (10 and 13).
The end play shall be 0.008 to 0.003 (6) Attach miniature airplane (15) to
inches. Adjust rings (6) to obtain scale dial (16 ) with screws (14).
proper end play. (7) Place scale dial (5) into bezel assem-
Note. It may be necessary to adjust posi- bly.
tion of gearset (11 and 12) to allow proper
alignment to gear (10). (8) No testing of bezel assembly is re-
quired.
(6) Connect capacitor (1), printed wiring
board (4), and post (5) to pitch plate
assembly (39) using screws (35). 16. Final Assembly.
(7) Slide pitch plate assembly (39) into a. Attitude Indicator, Part Number 141400-
indicator sphere (28) and attach into 01-01.
place with screws (26) and clamping Note. Refer to wire list, table 11 as necessary during
plate (27). reassembly.

19
 TM 55-661O-293-40

Table 11. Wire List for Attitude Indicator, Part Number Wire Termination
141400-01-01 No. Color From To
* Yellow B2 TB1-11
Wire Termination
No. Color From To * Black B2 TB1-10
* Blue B2 TB1-9
100 Brown T1-1 TB2-11 * Black B2 TB2-18
105 Red T1-2 TB2-10 * Red B2 TB2-19
110 Black T1-3 TB2-13
111 Black T1-3 T1-8 ● Leads are part item connected.
112 Bare T1-3 E2
115 Orange T1-4 TB2-6 (1) Reassemble shims (47, figure 2) gears
120 Yellow T1-5 TB2-7 (4 and 5), and shims (48). Attach
* White SR1 TB1-7
* with rings (49) and adjust rings until
White/Black SR1 TB1-2
* Gray SR1 TB1-5 there is 0.003- to 0.008-inch end play
* Violet SR1 TB1-8 on gears (4 and 5).
* Green SR1 TB1-12 (2) Reassemble housing and stator as-
* Yellow SR1 TB1-4
*
sembly (45) onto plate assembly (6)
Orange SR1 TB1-1 and attach with clamps (44 ) and
* Brown SR1 TB1-6
* Red SR1 TB1-11 screws (43). Slide bearing (46) into
* Blue SR1 TB1-9 plate assembly.
* Black SR1 TB1-10 (3) Slide yoke and sphere assembly (3)
* White MG2 TB2-10
*
into plate assembly (6). Using shims
Blue MG2 TB2-14
* (31, 32, 33, and 34), shim yoke and
Green MG2 TB2-8
* Yellow MG2 TB2-8 sphere assembly (3) for end play of
* Brown MG2 TB2-5 0.029 to 0.031 inch, Assemble ring
* Black MG2 TB2-14 (30).
* Orange MG2 TB2-1
* (4) Reassemble studs (2) onto bezel
Red MG2 TB2-3
* White MG1 TB1-1
assembly (1). Assemble screws (7)
* Blue MG1 TB1-7 through plate assembly (6) and into
* Green MG1 TB1-7 studs (2) .
* Yellow MG1 TB1-7
*
(5) Position motor-tachometer generator
Brown MG1 TB1-8
* (36) onto plate assembly (6). Attach
Black MG1 TB1-7
* Orange MG1 TB1-13 with clamps (38) and screws (37).
* Red MG1 TB1-12 (6) Assemble indicator subassembly (9)
* Red DS1-4 TB2-15 to plate assembly (6) using screws
* Brown DS1-3 TB2–17
*
(11, 39, and 40) and washers (10 and
Red DS1-2 TB2-15
* 41).
Brown DS1-1 TB2-17
* Green R17 T1-9 (7) Carefully work brush assembly (14)
* Yellow R17 T1-6 and bracket (35) onto slip ring, At-
* Red R17 TB2-9 tach bracket (35) to plate assembly
* Green R14 T1-9
* (6) using washers (16) and screws
Yellow R14 T1-7
* (17). Use a small pointed instrument
Red R14 TB2-A
* to align brushes on slip ring. The
Yellow M1 TB2-12
* outer-most brushes should contact the
Brown M1 TB2-16
* outer-most ring.
Bare C1 TB1-1
* Bare TB1-13
(8) Assemble transformer (19 ) and ter-
C1
* minal (28) using screws (27), clamps
Red/White B1 TB1-6
* (29), and studs (15).
Black/White B1 TB1-7
* Black B1 TB1-2 b. Alignment and Testing.
* Blue B1 TB1-5 (1) Refer to Section IV and calibrate two
* Yellow B1 TB1-4 standard test transmitters as outlined

20
 TM 55-6610-293-40

in paragraph 18a. Connect power and (4) Remove masking tape, apply 1/2 psi
standard transmitters to indicator as of filling gas, and flow solder between
shown in figure 8. sealing strip, case and bezel. Use
(2) Set standard transmitter dials to 180 enough solder to fill void caused by
degrees. If the Indicator does not raised edge of sealing strip. Solder
indicate zero (pitch trim and roll should form a continuous fillet when
trim variable resistors should be set soldering is completed. Clean soldered
to electrical zero) in pitch and roll, area with a cloth moistened with
align as follows: tetrachloroethylene, Federal Specifi-
cation O–T–236.
Warning: The Indicator will be ener-
gized during following steps (3) and Note. The filling gas shall be composed of
(4). Avoid contact with electrical con- an uncontaminated mixture of 5 ± 1 percent
carbon dioxide and the remainder helium.
nections and do not short out connec- The dew point of the mixed gas shall be no
tions with alignment instruments. higher than —75°F.
(3) Loosen setscrews (30, figure 4) and The carbon dioxide and helium filling
manually rotate Indicator to obtain a gases used shall be of 99.99 percent
pitch reading of zero degrees. Re- minimum purity. Oxygen c o n t e n t
tighten setscrews (30). shall not be greater than 0.002 percent
(4) Loosen screws (43, figure 2). Manu- for helium. This gas shall be used for
ally rotate housing and stator assem- the remainder of tests requiring gas.
bly (45) as necessary to obtain a roll (5) Apply 15 psi pressure of filling gas
reading of zero degrees. Retighten through vent, immerse in tetrachloro-
screws (43). ethylene, and examine for leaks. If
(5) Perform all tests outlined in Section unit leaks, rework seal.
IV. (6) Bake Indicator in oven for one hour
(6) Upon completion of tests of Section at 170° to 180°F with no vacuum
IV, cement-lock screws (7, 11, 12, 17, applied.
27, 37, 39, 40, and 43) using adhesive, (7) Vacuum-bake Indicator at minimum
Military Specification MIL-S-22473, of 27 inches of mercury for 2 hours.
Grade H. (8) Remove Indicator from oven, attach
(7) Secure all wires using Stur-D-Lace to a dry gas source at a pressure of
HL Soft Finish lacing tape. 1 to 2 psi, and allow to cool.
c. Canning and Painting (9) Cycle unit 3 to 5 times at 5 inches
of mercury vacuum and 5 psi pres-
(1) Hold cover firmly against bezel and
apply tetrafluoroethylene adhesive sure of filling gas.
tape to seam between case and bezel. (10) Cut vent (24) and allow pressure to
Press tape firmly against unit with release. Solder seal vent (24).
fingers. Tape should be centered over (11) Clean Indicator with tetrachloroethyl-
seam. ene.
(2) Place new sealing strip (20, figure 2) (12) Mask window of bezel assembly (1),
over tape and center over seam. Hold connector (23 ), knobs ( 1 and 4, figure
sealing strip in place with masking 3) and dials (2 and 5).
tape, Federal Specification UU-T-106. (13) Apply one coat of wash primer, Mili-
(3) Move Indicator to a sealing area and tary Specification MIL-C-15328 to
tack solder sealing strip about unit Indicator. Allow 30 minutes to dry.
using a heavy-duty soldering iron. Use (14) Apply two coats of black enamel,
solder, Federal Specification QQ-S- Military Specification MIL-E–5556 to
571, composition Sn60. Indicator, allowing 20 minutes of dry-

21
TM 55-6610-293-40

ing time between coats. Use xylene, side (as viewed from front) of cover
Federal Specification TT-X-916 to (21), 1-1/2 inches from top and ap-
thin enamel if required. proximately 1-1/2 inches from rear
(15) Allow to air dry for 2 hours. Remove of Indicator. The letters should be
masking tape from connector and win- 3/32 inch high. Use white epoxy
dow. coding ink, Wornow Ink Series “M”.
(16) Conduct the test procedures of Sec- “28 VOLT LIGHTING SYSTEM
tion IV. VOLTAGE NOT TO EXCEED 29.0
VOLTS”
(17) Transfer information from old iden-
tification plate (22, figure 2) onto new (19) Stencil characters “J1” 1/2 inch above
identification plate. Peel off protec- and centered over connector (23)
tive backing on plate. Center plate using ink of step (18). The letters
lengthwise on top of cover (21). Press should be 1/4 inch high.
plate into place using firm pressure. (20) Test Indicator in accordance with
(18) Stencil following information on right Section IV.

SECTION IV

FINAL TEST PROCEDURE

17. Introduction. leads shall be minimum. Lock dial to

The following test procedures should be per- rotor with dial on zero.
formed before and after overhaul and at such (4) Monitor ac voltage across two undes-
other times as necessary to check the operating ignated stator leads (each in turn)
characteristics of the Indicator. The test re- and stator lead Z. Turn transmitter
sults may be used to provide a basis for local- dial in direction of increasing num-
izing faults that may occur in the unit and bers. Designate as X stator lead in
therefore limit the extent of disassembly neces- which voltage increases before de-
sary for repairs. creasing. Designate as Y the stator
lead in which voltage decreases before
18. Testing. increasing.
a. Calibration of standard transmitters. (5) Disconnect power, external test equip-
Note. Two transmitters are required. ment, and lead C from lead Z.
(1) Designate standard transmitter rotor b. Pitch and Roll Sensing,
leads as H and C. Ground C lead. (1) Connect Indicator to standard trans-
(2) Designate one standard transmitter mitters and power sources as shown
stator lead as Z and connect it to lead in figure 8 and apply power. The OFF
c. indication shall disappear.
(3) Apply 26 Vac 400 cps across leads
H and C. Monitor ac voltage across (2) Set both standard transmitter dials to
two undesignated stator leads with ac a reading of 180 degrees. The Indi-
voltmeter. Monitor ac voltage across cator shall drive to within 1/2 degree
one of undesignated stator leads and of zero in pitch and roll (pitch and roll
H. Turn rotor until ac voltage across trim knobs shall be set at zero).
H and one undesignated stator lead is (3) Increase and then decrease dial set-
approximately maximum (about 35 ting on roll standard transmitter. The
volts), at the same time ac voltage Indicator shall indicate a right roll
across the two undesignated stator and then a left roll.

22
 TM 55-6610-293-40

position. Indicator shall indicate 8

degrees to 20 degrees right roll.
(2) Turn roll trim knob to full counter-
clockwise position. Indicator shall in-
dicate 8 degrees to 20 degrees
roll.
(3) Turn roll trim knob to zero.
e. Zeroing Adjustments.
(1) Place pitch standard transmitter to
183 degrees, Adjust Indicator to zero
pitch position using pitch trim knob.
(2) Loosen pitch trim knob from shaft
and position knob to zero. Retighten
pitch trim knob.
(3) Rotate pitch trim knob fully clock-
wise. The Indicator shall indicate a
minimum of 8 degrees dive.
(4) Rotate pitch trim knob fully counter-
clockwise. The Indicator shall indicate
a minimum of 16 degrees climb.
(5) Place pitch standard transmitter to
Figure 8. Test Connections 177 degrees. Adjust Indicator to zero
pitch position using pitch trim knob.
(4) Increase and then decrease dial set- Repeat steps (2), (3), and (4).
ting on pitch standard transmitter. (6) Place pitch standard transmitter to
The Indicator shall indicate a climb 180 degrees. Adjust pitch trim knob
and then a dive. for zero pitch reading on Indicator.
Note. If roll indications or pitch indica-
Loosen pitch trim knob and place knob
tions are reversed, recheck connections and on zero. Retighten pitch trim knob.
standard transmitter calibration. All visual (7) Place roll standard transmitter to 183
observation shall be made at a distance of degrees. Adjust Indicator to zero roll
two feet unless otherwise specified. position using roll trim knob.
(5) Reset both standard transmitters to (8) Loosen roll trim knob from shaft and
180 degrees. position knob to zero. Retighten roll
c. Pitch Trim trim knob.
(1) Turn pitch trim knob to full clockwise (9) Rotate roll trim knob fully clockwise.
position. Indicator shall indicate a The Indicator shall indicate between
minimum of 8 degrees dive. 8 degrees and 20 degrees right roll.
(2) Turn pitch trim knob to full counter- (10) Place roll standard transmitter to 177
clockwise position. Indicator shall degrees. Adjust Indicator to zero roll
indicate a minimum of 16 degrees position using roll trim knob.
climb. (11) Loosen roll trim knob from shaft and
(3) Turn pitch trim knob to zero position. position knob to zero. Retighten roll
Indicator shall indicate within 1/2 trim knob.
horizontal line width of zero. Loosen (12) Rotate roll trim knob fully counter-
and reset pitch trim knob as necessary. clockwise, The Indicator shall display
d. Roll Trim between 8 degrees and 20 degrees left
(1) Turn roll trim knob to full clockwise roll.

28
TM 55-6610-293-40

(13) Place roll standard transmitter to 180 Table 13. Pitch Follow-Up Accuracy
degrees. Adjust roll trim knob for
Indicator Roll
zero roll reading cm Indicator. Loosen Pitch Transmitter Presentation
roll trim knob and place knob on zero. Setting (degrees) (degrees)
Retighten roll trim knob. 270 90 ± 2 climb
f. Sensitivity. 240 60 ± 2 climb
(1) Rotate pitch standard transmitter 1/4 210 30 ± 1 climb
degree from zero in each direction. 150 30 ± 1 dive
The Indicator shall follow with a 120 60 ± 2 dive
smooth perceptible movement. 90 90 ± 2 dive
(2) Repeat step (1) with pitch trim knob i. Gimbal Freedom.
set in each of its extreme positions
(1) Rotate roll transmitter 360 degrees.
and moving the transmitter 1/2 de-
Indicator shall follow smoothly with-
gree instead of 1/4 degree.
out noticeable sticking, overshooting,
(3) Rotate roll standard transmitter 1/4 jumping, or hunting. Return roll
degree in each direction from zero. transmitter to 180 degrees.
The Indicator shall follow with a
(2) Repeat step (1) using pitch transmit-
smooth perceptible movement.
ter. Results shall be same.
(4) Repeat steps (3) with roll trim knob
set in each of its extreme positions j. Hunting and Jumping.
and moving transmitter 1/2 degree (1) Set amplitude of signals of both pitch
instead of 1/4 degree. transmitter and roll transmitter to
g. Follow-up Rate. zero. There shall be no noticeable
hunting or jumping of Indicator with
(1) Rotate roll transmitter at 300 degrees transmitter amplitudes set at zero.
per second minimum. The Indicator
(2) Return amplitude of signals of trans-
shall follow at 300 degrees per second
minimum. mitters to 26 Vat, 400 cps.
(2) Rotate pitch transmitter at 90 degrees (3) Rotate pitch transmitter at a rate be-
per second minimum. The Indicator tween O degrees and 20 degrees per
shall follow at a minimum of 90 second. Hunting and jumping shall
degrees per second. not exceed a peak-to-peak amplitude
of 1/8 degree.
h. Follow-up Accuracy. (4) Repeat step (3) for pitch transmitter
(1) Place roll transmitter in each position rate between 20 degrees and 90 de-
listed in table 12. The Indicator read- grees per second. Peak-to-peak ampli-
ings shall be as specified. tude shall not exceed 1/2 degree.
Table 12. Roll Follow-Up Accuracy (5) Repeat step (3) for pitch rate be-
tween 90 degrees and 300 degrees per
Indicator Roll
Roll Transmitter Presentation second. Peak-to-peak amplitude shall
Setting (degrees) (degrees) not exceed 1 degree. Return pitch
270 90 ± 2 right roll transmitter to 180 degrees.
240 60 ± 2 right roll (6) Repeat steps (3, 4, and 5) using roll
210 30 ± 1 right roll transmitter. The results shall be the
150 30 ± 1 left roll same.
120 60 ± 2 left roll k. Power Warning Indicator.
90 90 ± 2 left roll
(1) Remove power from Indicator. The
(2) Place pitch transmitter in each posi- word OFF shall immediately appear.
tion listed in table 13. The Indicator (2) Reapply power to Indicator. The word
readings shall be as specified. OFF shall immediately disappear.
24
 TM 55-6610-293-40
1. Interaction, (2) While still at this temperature, rub
(1) Connect two indicators to same pitch an ice cube on Indicator glass face for
transmitter. a period of 1 minute ± 5 seconds.
(2) Move pitch trim knob on one Indicator (3) Wipe glass dry. There shall be no
through its range. There shall be no evidence of water or oil fog.
more than 1/2 degree change in indi- n. Lighting.
cation on other Indicator. Remove (1) Apply 28 volts ac or dc between Indi-
second Indicator. cater connector pins K and L.
m. Fogging. (2) Compare lighting to a standard
(1) Place Indicator in a controlled tem- Lighting shall be comparable.
perature of 159.8°F (71°C) for one
19. Troubleshooting.
hour.
Use table 14 in conjunction with schematic
Note. Power to Indicator shall be left on diagram figure 9, to help localize and correct
during this test. trouble conditions found during testing.

Table 14. Trouble Shooting Data

Trouble Probable Cause Remedy

POWER FAILURE FLAG DOES NOT Defective power-off warning in- Replace indicator.
DISAPPEAR UPON APPLICATION OF dicator M1.
POWER Defective resistors R23 and R24. Replace resistors.
Defective capacitor C11, C13, Replace capacitors.
and C14.
Defective diodes CR2 thru CR5. Replace diodes.
Defective transformer T1. Replace transformer.
POWER FAILURE FLAG DOES NOT Defective power-off warning in- Replace indicator.
REAPPEAR ON REMOVAL OF POWER dicator M1.
INDICATOR DOES NOT FOLLOW IN Defective synchro B1. Replace synchro.
PITCH OR WILL NOT ZERO IN Defective transistors Q1 thru Replace as applicable.
PITCH Q3 and associated resistors and
capacitors.
Defective motor-tachometer gen- Replace motor-tachometer
erator MG1. generator.
INDICATOR DOES NOT FOLLOW IN Defective synchro B2. Replace synchro.
ROLL OR WILL NOT ZERO IN ROLL Defective transistors Q4 thru Replace as applicable.
Q7 and associated resistors and
capacitors.
Defective motor-tachometer gen- Replace motor-tachometer
erator MG2. generator.

PITCH TRIM KNOB DOES NOT DIS- Defective variable resistor R17. Replace resistor.
PLACE INDICATOR TO MINIMUM Refective resistors R4 and R5. Replace resistors.
REQUIRED POSITIONS Defective capacitors C4 and C2. Replace capacitors.

ROLL TRIM KNOB DOES NOT DIS- Defective variable resistor R14. Redate resistor.
PLACE INDICATOR TO MINIMUM Defective resistor R10. Replace resistor.
REQUIRED POSITIONS Defective capacitor C6. Replace capacitor.

INDICATOR HUNTS AND JUMPS Defective gear train or bearings. Replace or lubricate as re-
quired.
Detective motor-tachometer Replace motor-tachometer
generator MG1 and MG2. generator.

25
TM 95-6610-293-40

Figure 9.

26
 TM 55-6610-293-40

Reference
Designation Figure No. Index No.

B1 4 32
B2A 4 21
B2B 2 45
C1 4 1
DS1 3 12
El 2 14
E2 2 28
J1 2 23
Ml 3 18
MG1 4 36
MG2 2 36
R14 3 6
R17 3 8
SR1 4 23
T1 2 19
TB1 4 4
TB2 2 9

Figure 9—Continued

27
TM 55-6610-293-40

APPENDIX A

REFERENCES

Manual Number Manual Title

TM 38-750 Army Equipment Records Procedures

By Order of the Secretary of the Army:

HAROLD K. JOHNSON,
General, United States Army,
Official: Chief of Staff.
KENNETH G. WICKHAM,
Major General, United States Army,
The Adjutant General.

DISTRIBUTION:
To redistributed in accordance with DA Form 12-31 requirements for Direct and General Sup-
port maintenance instructions for UH-1A-1B, UH-1C, UH-1D aircraft.

* U. S. GOVERNMENT PRINTING OFFICE: 1967-304430/49

28
TM 55-6610-293-40,
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