Bell OH-58A User manual

TM 55-1520-228-BD
TECHNICAL MANUAL
OPERATORS, AVIATION UNIT,
AND AVIATION
INTERMEDIATE MAINTENANCE
FOR
HELlCOPTER,
OBSERVATION
OH-58A & OH-58C
ITEM NSN
INSIDE FRONT COVER
This publication supersedes
TM 55-1520-228-BD dated
17 August 1990.
CHAPTER 1. GENERAL INFORMATION
CHAPTER 2. ASSESSING BATTLEFIELD DAMAGE
CHAPTER 3. GENERAL REPAIR
CHAPTER 4. AIRFRAME
CHAPTER 5. ALIGHTING GEAR
CHAPTER 6. POWER PLANT
CHAPTER 7. ROTORS
CHAPTER 8. DRIVE TRAIN SYSTEM
CHAPTER 9. HYDRAULIC SYSTEM
CHAPTER 10: INSTRUMENT SYSTEMS
CHAPTER 11. ELECTRICAL SYSTEM
CHAPTER 12. FUEL SYSTEM
CHAPTER 13. FLIGHT CONTROLS
CHAPTER 14. UTILITY SYSTEM
CHAPTER 15. ENVIRONMENTAL CONTROL SYSTEM
CHAPTER 16. MISSION EQUIPMENT
CHAPTER 17. EMERGENCY EQUIPMENT
APPENDIX A . REFERENCES
APPENDIX B. SPECIAL OR FABRICATED TOOLS
APPENDIX C. EXPENDABLE/DURABLE SUPPLIES & MATERIALS
APPENDIX D. SUBSTITUTE MATERIALS/PARTS
APPENDIX E. BDAR TRAINING PROCEDURES
HEADQUARTERS, DEPARTMENT OF THE ARMY
4 January 1991
APPENDIX F. AVIONICS CONFIGURATIONS

TM 55-1520-228-BD
BDAR FIXES SHALL BE USED ONLY IN COMBAT
AT THE DISCRETION OF THE COMMANDER
AND SHALL BE REPAIRED BY STANDARD MAINTENANCE PROCEDURES
AS SOON AS PRACTICABLE AFTER THE MISSION IS COMPLETED.
BDAR TECHNIQUES IN THIS MANUAL PERTAIN to the following helicopters:
OH-58A Helicopter, Observation NSN 1520-00-169-7137
OH-58C Helicopter, Observation NSN 1520-01-020-4216

TM 55-1520-228-BD
WARNING DATA
Personnel performing operations, procedures, and practices which are included or
implied in this technical manual shall observe the general following warnings.
Disregard of these warnings can cause serious injury or death.
WARNINGS
FLIGHT SAFETY
The standards contained herein allow aircraft to be flown with battle damage
substantially in excess of peacetime limits. Under no circumstances shall this
manual be used entirely or in part for peacetime maintenance of the aircraft.
Assessment of aircraft battle damage requires extreme care and diligence and strict
adherence to the instructions and standards contained in this manual. If at any
stage of damage assessment the assessor believes that oversights or errors have
been made, the assessment shall be stopped at that point and repeated from the
beginning.
Under no circumstances shall the requirements of this manual be waived
or circumvented without the express approval of the commander or his designated
representative.
EXPLOSIVES
Battle damaged areas should be inspected for unexploded ordnance before attempting
repairs. Disposal of unexploded ordnance should be accomplished by qualified
personnel.
ARMAMENT
Loaded weapons or weapons being loaded or unloaded shall be pointed in a direction
which offers the least exposure to personnel or property in the event of accidental
firing. Personnel shall remain clear of hazardous area.
CLEANING SOLVENTS
Cleaning solvents may be flammable and toxic. Use only in well-ventilated areas.
Avoid inhalation of vapor and skin contact. Do not use solvents near open flame or
in areas where very high temperatures prevail. Solvent flash point must not be less
than 100°F.
COMPRESSED AIR
Compressed air can blow dust into eyes. Wear eye protection. Do not exceed 30 psig
air pressure.
ELECTROLYTE
Battery Electrolyte (Potassium Hydroxide) is corrosive. Wear rubber gloves, apron,
and face shield when handling leaking batteries. If potassium hydroxide is spilled
on clothing or other material, wash immediately with clean water. If spilled on
personnel, immediately start flushing the affected area with clean water. Continue
washing until medical assistance arrives.
a

TM 55-1520-228-BD
HIGH VOLTAGE
is used in this equipment.
DEATH ON CONTACT
may result if personnel fail to observe safety precautions.
Never work on electronic equipment unless there is another person nearby who is
familiar with the operation and hazards of the equipment and who is competent in
administering first aid. When the technician is aided by operators, he must warn
them about dangerous areas.
Whenever the nature of the operation permits, keep one hand away from the equipment
as to reduce the hazard of current flowing through vital organs of the body.
Do not be mislead by the term “low voltage.” Potentials as low as 50 volts may
cause death under adverse conditions. For Artificial Respiration, refer to FM 21-11.
b

TM 55-1520-228-BD
EXTERNAL STORES
Prior to any helicopter maintenance functions that require external stores be
removed, JETTISON cartridge shall be removed.To prevent injury to personnel
and damage to equipment, remove jettison cartridges from stores ejection device
prior to placing helicopter in a hangar.
All ground safety pins must be removed before flight.Failure to do so will prevent
emergency jettison of stores.
FIRE EXTINGUISHER
Exposure to high concentrations of monobromotrifluoromethane (CF3BR) extinguishing
agent or decomposition products should be avoided.The liquid should not be allowed
to come into contact with the skin, as it may cause frost bite or low temperature
burns.
FUELING AND FUEL REPAIRS
When refueling helicopter,the refueling vehicle must be parked a minimum of 20 feet
from the helicopter.Before starting the fueling operation, always insert fueling
nozzle grounding cable of fuel truck into GROUND HERE receptacle.Refer to FM
10-68.When defueling,turn off all electrical switches and disconnect external
power from the helicopter.The helicopter must be electrically grounded prior to
defueling.
Fuel line and tank repairs often involve handling of highly flammable material.
Mishandling can result in serious injury or death.
GROUNDING HELICOPTER
The helicopter should be electrically grounded when parked to dissipate static
electricity.Turn off all power switches before making electrical connections or
disconnections.
HIGH PRESSURE
Extremely high pressure can occur during and after operation of certain equipment.
If this pressure is not relieved before working on this equipment, serious injury or
death may occur.Be sure to open all drains and vents before beginning disassembly.
HYDRAULIC FLUID
Prolonged contact with liquid or mist can irritate eyes and skin. Wear rubber
gloves when handling liquid.After contact with skin, inmmediately wash contacted
area with soap and water.If liquid contacts eyes,flush immediately with clear
water. If liquid is swallowed, do not induce vomiting, get immediate medical atten-
tion.If prolonged exposure with mist is likely, wear an appropriate respirator.
When fluid is decomposed by heating, toxic gases are released.
c

TM 55-1520-228-BD
LIFTING
Lifting or moving heavy equipment incorrectly can cause serious injury. Do not try
to lift or move more than 50 pounds by yourself. Bend legs while lifting. D
O not
support heavy weight with your back.
Always use assistants during lifting opera-
tions.
Use guide ropes to move hanging assemblies. Lack of attention or being in
an improper position during lifting operations can result in serious injury.
Pay
close attention to movements of assemblies being lifted. Do not stand under lifted
assembly or in a position where you could be pinned against another object. Watch
your footing.
NOISE
Sound pressure levels in and around this aircraft during operating conditions exceed
the Surgeon General’s hearing conservation criteria, as defined in TB MED 501.
Hearing protection devices such as aviator helmet or ear plugs are required to be
worn.
RADIOACTIVE MATERIALS
Self-luminous dials and ignition units may contain radioactive materials. If such
an instrument or unit is broken or becomes unsealed, avoid personal contact. Use
forceps or gloves made of rubber or polyethylene to pick up contaminated material.
Place materials and gloves in a plastic bag. Seal bag and dispose of it as radio-
active waste in accordance with AR 708-1 and TM 3-261 (Refer to TB 43-0108). Repair
shall conform to requirements in AR 385-11.
SANDING DUST
Sanding on reinforced laminated glass produces fine dust that may cause skin
and lung irritations. Observe necessary protective measures.
STARTING HELICOPTER
Starting and operation of the helicopter will be performed only by authorized
personnel.
TOXIC POISONS
Turbine fuels, lubricating oils, and adhesives contain additives which are poisonous
and readily absorbed through the skin.
Do not allow them to remain on skin longer
than necessary. Wear protective equipment.
d

TM 55-1520-228-BD
C 1
CHANGE HEADQUARTERS
DEPARTMENT OF THE ARMY
NO. 1 WASHINGTON, D.C., 1 September 2005
TECHNICAL MANUAL
OPERATORS, AVIATION UNIT, AND AVIATION INTERMEDIATE
MAINTENANCE
BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR
FOR HELICOPTER, OBSERVATION OH-58A & OH-58C
DISTRIBUTION STATEMENT A:Approved for public release; distribution is unlimited.
TM 55-1520-228-BD, dated 4 January 1991, is changed as follows:
1. Remove and insert pages as indicated below. New or changed text material is indicated by a vertical
bar in the margin. An illustration change is indicated by a miniature pointing hand.
Remove Pages Insert Pages
------------- A/(B blank)
i and ii i and ii
1-5 and 1-6 1-5 and 1-6
2. Retain this sheet in front of manual for reference purposes.
DISTRIBUTION:
To be distributed in accordance with Initial Distribution Number (IDN) 311704, requirements for
TM 55-1520-228-BD.
By Order of the Secretary of the Army:
PETER J. SCHOOMAKER
General, United States Army
Chief of Staff
Official:
SANDRA R. RILEY
Administrative Assistant to the
Secretaryof the Army
0518801

TM 55-1520-228-BD
*Zero in this column indicates an original page.
LIST OF EFFECTIVE PAGES
Insert latest changed pages. Dispose of superseded pages in accordance with regulations.
NOTE: On a changed page, the portion of the text affected by the latest change is indicated by a vertical
line, or other change symbol, in the outer margin of the page. Changes to illustrations are indicated by
miniature pointing hands. Changes to wiring diagrams are indicated by shaded areas.
Dates of issue for original and changed pages are:
Original………… 4 January 1991 Change 1……… 1 September 2005
TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS 762. CONSISTING OF THE FOLLOWING:
Page *Change Page *Change
No. No. No. No.
Cover.....................................................0
A through d............................................0
i..............................................................1
ii through ix............................................0
x blank...................................................0
1-1 through 1-5......................................0
1-6.........................................................1
1-7 through 1-11....................................0
1-12 blank..............................................0
2-1 through 2-9......................................0
2-10 blank..............................................0
3-1.........................................................0
3-2 blank................................................0
4-1 through 4-70....................................0
5-1 through 5-6......................................0
6-1 through 6-12....................................0
7-1 through 7-8......................................0
8-1 through 8-12....................................0
9-1 through 9-17....................................0
9-18 blank ............................................0
10-1.......................................................0
10-2 blank..............................................0
11-1 through 11-49................................0
11-50 blank ...........................................0
12-1 through 12-9..................................0
12-10 blank ...........................................0
13-1 through 13-14................................0
14-1 and 14-2........................................0
15-1 through 15-11................................0
15-12 blank ...........................................0
16-1.......................................................0
16-2 blank..............................................0
17-1.......................................................0
17-2 blank..............................................0
A-1.........................................................0
A-2 blank...............................................0
B-1 and B-2...........................................0
C-1 through C-4 ....................................0
D-1 through D-11..................................0
D-12 blank.............................................0
E-1 and E-2...........................................0
F-1 through F-22...................................0
Index-1 through index-5........................0
Index-6 blank ........................................0
Glos-1 through Glos-8 ..........................0
Change 1 A/(B blank)

TM 55-1520-228-BD
Technical Manual
No. 55-1520-228-BD
HEADQUARTERS
DEPARTMENT OF THE ARMY
TECHNICAL MANUAL
OPERATORS, AVIATION UNIT, AND AVIATION INTERMEDIATE MAINTENANCE
BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR
FOR HELICOPTER, OBSERVATION OH-58A & OH-58C
REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS
You can help improve this manual. If you find any mistakes, or if you know of a way to improve these procedures, please let us
know. Mail your letter or DA Form 2028 (Recommended Changes to Publications and Blank Forms) located in the back of this
manual, directly to: Commander, U.S. Army Aviation and Missile Command, ATTN: AMSAM-MMC-MA-NP, Redstone Arsenal,
TABLE OF CONTENTS
CHAPTER 1 -
Section I.
Section II.
HOW TO USE THIS MANUAL
GENERAL INFORMATION
Introduction . . . . . . . . . . . . . . . . . . . . . . . .
Standards and Practices. . . . . . . . . . . . . . . . . . .
Section III. Tasks and Responsibilities . . . . . . . . . . . . . . . . .
CHAPTER 2 -
ASSESSING BATTLEFIELD DAMAGE
Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .
Section II. General Fault Assessment Table . . . . . . . . . . . . . . .
CHAPTER 3 - GENERAL REPAIRS . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER 4 - AIRFRAME
Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .
Section II. Expedient Structural Repairs . . . . . . . . . . . . . . . .
CHAPTER 5 - ALIGHTING GEAR
Section I.
Introduction. . . . . . . . . . . . . . . . . . . . . . . .
Section II. Skid Tube. . . . . . . . . . . . . . . . . . . . . . . . . .
Section III. Skid Damage. . . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER 6 - POWER PLANT INSTALLATION
Section I.
Introduction. . . . . . . . . . . . . . . . . . . . . . . .
Section II.
Component Expedient Fixes. . . . . . . . . . . . . . . . . .
Page
viii
1-1
1-3
1-5
2-1
2-3
3-1
4-1
4-49
5-1
5-1
5-4
6-1
6-1
Change 1 i
the World Wide Web. Our fax number is: DSN 788-6546 or Commercial 256-842-6546. Our e-mail address is
AL 35898-5000. A reply will be furnished to you. You may also provide DA Form 2028 information to AMCOM via e-mail, fax, or
[email protected]. Instructions for sending an electronic 2028 may be found at the back of this manual immediately
preceding the hard copy 2028. For the World Wide Web use: https://amcom2028.redstone.army.mil.
Distribution Statement: Approved for public release; distribution is unlimited.
WASHINGTON, D.C., 4 January 1991

TM 55-1520-228-BD
TABLE OF CONTENTS (Cont)
Page
CHAPTER 7 - ROTORS
Section I. Introduction. . . . . . . . . . . . . . . . . . .
Section II. Repairs . . . . . . . . . . . . . . . . .
CHAPTER 8 - DRIVE TRAIN SYSTEM
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Repair. . . . . . . . . . . . . . . . . . . . . . . .
CHAPTER 9 - HYDRAULIC
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Lines and Hoses. . . . . . . . . . . . . . . . . . .
Section III. Seals, Packings, and Gaskets . . . . . . . . . . . . .
CHAPTER 10 - INSTRUMENTS
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Instrument Replacement . . . . . . . . . . . . . .
CHAPTER 11 -ELECTRICAL AND AVIONICS SYSTEM
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Electrical and Avionics Wiring Damage. . . . . . . .
CHAPTER 12 - FUEL SYSTEMS
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Lines and Hoses. . . . . . . . . . . . . . . . . . .
Section III. Fuel Cell Damage. . . . . . . . . . . . . . . .
CHAPTER 13 - FLIGHT CONTROLS SYSTEM
Section I. Introduction. . . . . . . . . . . . . . . . . . . . .
Section II. Flight Control Tubes. . . . . . . . . . . . . . . . .
CHAPTER 14 - UTILITY SYSTEMS
Section I. Introduction. . . . . . . . . . . . . . . . . . . .
Section II. De-Ice Valve or Control. . . . . . . . . . . . . . .
CHAPTER 15 - ENVIRONMENTAL CONTROL SYSTEM
Section I. Introduction, . . . . . . . . . . . . . . . . . . . .
Section II. Rigid Plastic Ventilation Duct . . . . . . . . . . .
Section III. Bleed Air Line Damage. . . . . . . . . . . . . . .
7-1
7-1
8-1
8-1
9-1
9-1
9-14
10-1
10-6
11-1
11-6
12-1
12-1
12-4
13-1
13-1
14-1
14-1
15-1
15-1
15-9
ii

CHAPTER 16 -
CHAPTER 17 -
CHAPTER 18 -
Section I.
Section II.
CHAPTER 19 -
APPENDIX A -
APPENDIX B -
APPENDIX C -
APPENDIX D -
APPENDIX E -
APPENDIX F -
GLOSSARY . .
INDEX . . .
Figure
1-1
1-2
1-3
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
4-18
4-19
4-20
4-21
4-22
TM 55-1520-228-BD
TABLE OF CONTENTS (Cont)
Page
HOIST AND WINCHES. . . . . . . . . . . . . . . . . . . . . .
16-1
AUXILIARY POWER PLANT . . . . . . . . . . . . . . . . . . . .
17-1
MISSION EQUIPMENT . . . . . . . . . . . . . . . . . . . . . .
Introduction. . . . . . . . . . . . . . . . . . . . . . . . 18-1
Gun and Mount Assembly . . . . . . . . . . . . . . . . . . . 18-1
EMERGENCY EQUIPMENT. . . . . . . . . . . . . . . . . . . . .
19-1
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
SPECIAL OR FABRICATED TOOLS . . . . . . . . . . . . . . . . . . . . . . . B-1
EXPENDABLE/DURABLE SUPPLIES AND MATERIALS . . . . . . . . . . C-1
SUBSTITUTE MATERIALS/PARTS. . . . . . . . . . . . . . . . . . D-1
BDAR TRAINING PROCEDURES. . . . . . . . . . . . . . . . .
. . E-1
AVIONICS CONFIGURATION. . . . . . . . . . . . . . . . . . . .
F-1
✎ . . . . ✎ .. . .... ... . . . . . ...
GLOS-1
. . . . . . . . .... . ... ... .. INDEX-1
LIST OF ILLUSTRATIONS
Title
DA Form 2408-13. . . . . . . . . . . . . . . . . . . . . . .
DA Form 2408-18. . . . . . . . . . . . . . . . . . . . . . .
Damage Assessment Markings (Sheet 1 of 3). . . . . . . . .
Aircraft Sections. . . . . . . . . . . . . . . . . . . . . .
DA Form 2404. . . . . . . . . . . . . . . . . . . . . . . .
Evaluating Damage to Angles, Channels, and Z-Angles. . . . .
Damaged Cross Section. . . . . . . . . . . . . . . . . . . .
Measuring Skin Panel Damage. . . . . . . . . . . . . . . . .
Measuring Damage in Webs and Panels. . . . . . . . . . . . .
Measuring Damage in Honeycomb Sandwich Panels. . . . . . . .
OH-58 Helicopter. . . . . . . . . . . . . . . . . . . . . .
Airframe Reference Lines. . . . . . . . . . . . . . . . . .
Cockpit. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuselage Pylon Support Structure (Sheet 1 of 5). . . . . . .
Upper and Lower Shell Structure. . . . . . . . . . . . . . .
Aft Fuselage Structure.. . . . . . . . . . . . . . . . . .
Tail Boom . . . . . . . . . . . . . . . . . . . . . . . . .
Cowling and Firewalls . . . . . . . . . . . . . . . . . . . .
Typical Former Repair (Sheet 1 of 2) . . . . . . . . . . . .
Cutout in Damage Skin. . . . . . . . . . . . . . . . . . . .
Patch Plate. . . . . . . . . . . . . . . . . . . . . . . . .
Typical Patch Plate Repair . . . . . . . . . . . . . . . . .
Expedient Cap/Longeron Repair. . . . . . . . . . . . . . . .
Repair of Damage Bulkhead Flange . . . . . . . . . . . . . .
Typical Combination Repair (Sheet 1 of 2). . . . . . . . . .
Page
1-7
1-8
1-9
4-3
4-6
4-8
4-9
4-10
4-11
4-13
4-17
4-18
4-19
4-20
4-25
4-26
4-27
4-28
4-52
4-54
4-55
4-56
4-58
4-60
4-61
iii

TM 55-1520-228-BO
LIST OF ILLUSTRATIONS (Cont)
Figure Title
Page
4-23
4-24
4-25
4-26
4-27
4-28
4-29
4-30
5-1
5-2
5-3
5-4
5-5
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
7-1
7-2
7-3
7-4
7-5
8-1
8-2
8-3
9-1
9-2
9-3
9-4
9-5
9-6
9-7
9-8
,9-9
9-10
9-11
9-12
Damaged Honeycomb Core Panel, Small Damage to One Skin
and Core... . . . . . . . . . . . . . . . . . . . . . . .
Damaged Honeycomb Core Panel, 2-8 Inch Damage - One Skin
and Core. . . . . . . . . . . . . . . . . . . . . . . . .
Repaired Honeycomb Core Panel, 2-8 Inch Damage - One Skin
and Core. . . . . . . . . . . . . . . . . . . . . . . . . .
Damaged Repair, Accessible One Side Only . . . . . . . . . .
Patch Plates, One Side Accessible Repair . . . . . . . . . .
Repair of Honeycomb Core Panel, Damage Over 8 Inches - Both
Skins and Core. . . . . . . . . . . . . . . . . . . . . . .
Fracture Lacing with Safety Wire . . . . . . . . . . . . . .
Tail Boom Skin Damage. . . . . . . . . . . . . . . . . . . .
Landing Gear and Support Installation. . . . . . . . . . . .
Skid Tube Damage Zones. . . . . . . . . . . . . . . . . . .
Skid Repair. . . . . . . . . . . . . . . . . . . . . . . . .
Clamp Repair. . . . . . . . . . . . . . . . . . . . . . . .
Fabricated Clamp. . . . . . . . . . . . . . . . . . . . . .
T63 Series Engine. . . . . . . . . . . . . . . . . . . . . .
Blocking Plate Installation. . . . . . . . . . . . . . . . .
Double-Check Valve System, Possible Alternatives . . . . . .
Wood Plug. . . . . . . . . . . . . . . . . . . . . . . . . .
Sealant for Small Holes... . . . . . . . . . . . . . . . .
Repair Using Screw, Washer and Gasket. . . . . . . . . . . .
Hose Assembly, Sealant, Nut, and Bolt. . . . . . . . . . . .
Sheet Metal with Sealant and/or Cherry Rivets. . . . . . . .
Main Rotor System. . . . . . . . . . . . . . . . . . . . . .
Tail Rotor System. . . . . . . . . . . . . . . . . . . . . .
Rotor Blades, Damage Sensitive Areas . . . . . . . . . . . .
Rotor Blade Repair, Application of Tape. . . . . . . . . . .
Repair Areas - Main Rotor B1ades . . . . . . . . . . . . . .
Drive Train System (Sheet 1 of 4). . . . . . . . . . . . .
External Components - Transmission Oil System. . . . . . . .
Flex Duct Repair (Sheet 1 of 2) . . . . . . . . . . . . . . .
Hydraulic System. . . . . . . . . . . . . . . . . . . . . .
Hydraulic System Schematic . . . . . . . . . . . . . . . . .
Two-Part Fitting. . . . . . . . . . . . . . . . . . . . . .
Four-Part Fitting. . . . . . . . . . . . . . . . . . . . . .
Using Tube Cutter. . . . . . . . . . . . . . . . . . . . . .
Properly Burred Tubing . . . . . . . . . . . . . . . . . . .
Damaged Tube Section-Straight Tube . . . . . . . . . . . . .
Splice Repair Assembly . . . . . . . . . . . . . . . . . . .
Repair Fitting and Tube Installation . . . . . . . . . . . .
Damaged Tube Section-Complex Bends . . . . . . . . . . . . .
Splice Adapter Assembly Installation . . . . . . . . . . . .
Installation of Socket and Sleeve. . . . . . . . . . . . . .
4-64
4-64
4-64
4-66
4-66
4-67
4-69
4-70
5-2
5-2
5-5
5-5
5-6
6-2
6-5
6-7
6-8
6-9
6-9
6-10
6-12
7-2
7-3
7-5
7-7
7-8
8-2
8-8
8-9
9-2
9-3
9-4
9-5
9-5
9-7
9-7
9-8
9-8
9-10
9-10
9-12
iv

TM 55-1520-228-BD
Figure
9-13
9-14
11-1
11-2
11-3
11-4
11-5
11-6
11-7
11-8
11-9
11-10
11-11
11-12
11-13
11-14
11-15
11-16
11-17
11-18
11-19
11-20
11-21
11-22
11-23
11-24
11-25
11-26
11-27
11-28
11-29
11-30
11-31
11-32
11-33
11-34
11-35
11-36
11-37
11-38
11-39
11-40
11-41
11-42
11-43
11-44
11-45
LIST OF ILLUSTRATIONS (Cont)
Title
Assembly of MS Fitting . . . . . . . . . . . . . . . . . . .
Union Connection. . . . . . . . . . . . . . . . . . . . . .
Circuit Identification . . . . . . . . . . . . . . . . . . .
Crimp Splice. . . . . . . . . . . . . . . . . . . . . . . .
Splicing with Terminal Lug Barrel. . . . . . . . . . . . . .
Twist Wire Splice . . . . . . . . . . . . . . . . . . . . .
Replacement Section; Twist Wire Splice . . . . . . . . . . .
Metal Casing Splice Splice. . . . . . . . . . . . . . . . .
Bolted Terminal Lug Repair of Large Wires. . . . . . . . . .
Replacement Section; Terminal Lug Repair . . . . . . . . . .
Ram Wire Repair . . . . . . . . . . . . . . . . . . . . . .
Heat-Shrinkable Tape . . . . . . . . . . . . . . . . . . . .
Insulation Repair with Sleeving. . . . . . . . . . . . . . .
Shielded Cable Repair Preparation. . . . . . . . . . . . . .
Shielded Cable Splice Preparation. . . . . . . . . . . . . .
Shielded Cable Spliced . . . . . . . . . . . . . . . . . . .
Shielded Cable Repair... . . . . . . . . . . . . . . . . .
Pigtail Method Repair . . . . . . . . . . . . . . . . . . .
Substitute Shielded Braid Repair . . . . . . . . . . . . . .
Shield Terminator Repair Preparation . . . . . . . . . . . .
Shield Terminator Repair.. . . . . . . . . . . . . . . . .
Nickel-Plated Shield Terminator Preparation. . . . . . . . .
Nickel-Plated Shield Terminator Repair . . . . . . . . . . .
Terminal Lug Repair. . . . . . . . . . . . . . . . . . . . .
Self-Clinching Cable Strap . . . . . . . . . . . . . . . . .
Self-Clinching Cable Strap and Tool. . . . . . . . . . . . .
Tie Tape Repair Procedure. . . . . . . . . . . . . . . . . .
Coax Splice Preparation.. . . . . . . . . . . . . . . . . .
Coax Splice Inner Sleeve. . . . . . . . . . . . . . . . . .
Coax Splice Shield Sleeve. . . . . . . . . . . . . . . . . .
Coax Splice with Tubing Sleeve . . . . . . . . . . . . . . .
Coax Splice with Cable Braid over Barrier Sleeves. . . . . .
Coax Repair with Cable Braid over Barrier Sleeve . . . . . .
Component Bypass. . . . . . . . . . . . . . . . . . . . . .
Connector Pin and Socket.. . . . . . . . . . . . . . . . .
Damaged Connector and Pigtail. . . . . . . . . . . . . . . .
Circuit Breakers, . . . . . . . . . . . . . . . . . . . . .
Typical Circuit Breaker Connection . . . . . . . . . . . . .
Construction of Fuse Link. . . . . . . . . . . . . . . . . .
Splicing Bus Bars. . . . . . . . . . . . . . . . . . . . . .
Lengthening Bus Bars... . . . . . . . . . . . . . . . . .
Battery, Storage BB-476/A, Cell Layout . . . . . . . . . . .
Block Diagram Power Relay, Check and Test. . . . . . . . . .
Location of Power Relays. . . . . . . . . . . . . . . . . .
Block Diagram, Typical Power Relays. . . . . . . . . . . . .
Jumper Wire Fabrication.. . . . . . . . . . . . . . . . . .
Frequency vs. Wave length. . . . . . . . . . . . . . . . .
Page
9-12
9-13
11-2
11-8
11-10
11-11
11-12
11-12
11-14
11-14
11-14
11-16
11-16
11-17
11-18
11-19
11-20
11-22
11-23
11-24
ll-25
11-25
11-25
11-26
11-28
11-28
11-29
11-29
11-31
11-31
11-31
11-32
11-32
11-33
11-33
11-34
11-36
11-36
11-37
11-39
11-39
11-40
11-41
11-43
11-44
11-44
11-46
v

TM 55-1520-228-BD
LIST OF ILLUSTRATIONS (Cont)
Figure Title
Page
11-46
11-47
12-1
12-2
12-3
12-4
12-5
13-1
13-2
13-3
13-4
13-5
13-6
13-7
13-8
13-9
13-10
13-11
14-1
15-1
15-2
15-3
15-4
15-5
15-6
15-7
F-1
F-2
F-3
F-4
F-5
F-6
F-7
F-8
F-9
F-10
Table No.
2-1
2-2
4-1
4-2
4-3
4-4
4-5
Preparation of Coax . . . . . . . . . . . . . . . . . . . .
Installation of Field Expedient Antenna. . . . . . . . . . .
0H-58 Fuel System. . . . . . . . . . . . . . . . . . . . . .
Emergency Mechanical Clamp Repair . . . . . . . . . . . . .
Mixing Instruction for Sealant Cartridges. . . . . . . . . .
Rubber Repair Plug Assembly. . . . . . . . . . . . . . . . .
Plug Modification for Three Plain Repair . . . . . . . , . .
OH-58 Flight Controls Schematic. . . . . . . . . . . . . . .
Collective Flight Control. . . . . . . . . . . . . . . . . .
Cyclic Flight Control . . . . . . . . . . . . . . . . . . . .
Flight Control Actuators. . . . . . . . . . . . . . . . . .
Anti-Torque Controls (Sheet 1 of 2). . . . . . . . . . . . .
Control Tube Dimensions. . . . . . . . . . . . . . . . . . .
Suggested Repair for Control Rods or Tubes . . . . . . . . .
Control Rod with Bearing and Clevis Assemblies . . . . . . .
Flattened End of Fabricated Flight Control . . . . . . . . .
Corner Rounding on Fabricated Flight Control . . . . . . . .
Bearing Assembly Connection of Fabricated Flight Control . .
Engine De-Ice System. . . . . . . . . . . . . . . . . . . .
Bleed Air Heating and Ventilating System A & C . . . . . . .
Heating and Ventilating System (Bleed Air) A Model . . . . .
Heating and Ventilating System (Bleed Air) C Model . . . . .
Combustion Heater. . . . . . . . . . . . . . . . . . . . . .
Shroud Heater System Schematic . . . . . . . . . . . . . . .
Bleed Air Line Installation. . . . . . . . . . . . . . . . .
Bleed Line Patch Repair. . . . . . . . . . . . . . . . . . .
Intercom System (Sheet 1 of 2).. . . . . . . . . . . . . .
UHF/AM Communications System (Sheet 1 of 2). . . . . . . . .
VHF/AM Communications System and Connecting Cables . . . . .
VHF/FM Communication System. . . . . . . . . . . . . . . . .
Gyromagnetic Compass Set AN/ASN-43 and Connecting Cable
(Sheet 1 of 2) . . . . . . . . . . . . . . . . . . . . . . .
Direction Finder Set AN/ARN-89 (Sheet 1 of 2). . . . . . . .
Radio Receiving Set AN/ARN-123(V)1 . . . . . . . . . . . . .
Radar Altimeter System AN/APN-209. . . . . . . . . . . . . .
Transponder (IFF) System AN/APX-72, AN/APX-100 . . . . . . .
Radar Warning System AN/APR-39 . . . . . . . . . . . . . . .
LIST OF TABLES
Title
General Decision Logic . . . . . . . . . . . . . . . . . . .
General Assessment Table . . . . . . . . . . . . . . . . . .
Aircraft Structure Damage Assessment Procedures. . . . . . .
Damage Limits Forward Fuselage - Condition I . . . . . . . .
Damage Limits Aft Fuselage - Condition I . . . . . . . . . .
Damage Limits Tail Boom and Landing Gear - Condition I . . .
Damage Limits Forward Fuselage - Condition II. . . . . . . .
11-47
11-49
12-2
12-5
12-7
12-9
12-9
13-2
13-5
13-6
13-7
13-8
13-10
13-10
13-12
13-13
13-13
13-13
14-2
15-2
15-3
15-4
15-5
15-6
15-10
15-11
F-2
F-4
F-6
F-8
F-10
F-12
F-14
F-16
F-18
F-21
Page
2-2
2-3
4-2
4-31
4-36
4-39
4-39
vi

TM 55-1520-228-BD
LIST OF TABLES (Cont)
Table No.
4-6
4-7
4-8
5-1
6-1
7-1
8-1
9-1
9-2
11-1
11-2
11-3
11-4
11-5
11-6
11-7
12-1
13-1
13-2
13-3
15-1
D-1
D-2
D-3
D-4
D-5
D-6
D-7
F-1
F-2
F-3
F-4
F-5
F-6
F-7
F-8
F-9
F-10
F-11
Title
Damage Limits Aft Fuselage - Condition II. . . . . . . . . .
Damage Limits Tail Boom and Landing Gear - Condition II. . .
Metal Substitution Chart. . . . . . . . . . . . . . . . . .
Assessment Procedure Logic . . . . . . . . . . . . . . . . .
Engine BDAR Assessment Logic . . . . . . . . . . . . . . . .
Assessment Procedures. . . . . . . . . . . . . . . . . . . .
Drive Train System BDAR Assessment Procedures. . . . . . . .
Assessment Logic. . . . . . . . . . . . . . . . . . . . . .
Seals Reference and Temperature Guides Chart . . . . . . . .
Electrical and Avionics Assessment Logic . . . . . . . . . .
Function and Designation Letters . . . . . . . . . . . . . .
Unshielded Crimp Splice Application. . . . . . . . . . . . .
Wire Repair Segments. . . . . . . . . . . . . . . . . . . .
Shielded Cable Repair . . . . . . . . . . . . . . . . . . .
Terminal Lugs. . . . . . . . . . . . . . . . . . . . . . . .
Fuse Link Strands. . . . . . . . . . . . . . . . . . . . . .
Fuel System Assessment Procedures. . . . . . . . . . . . . .
Flight Control System Assessment Procedures. . . . . . . . .
Nominal Tube Splice Sizes. . . . . . . . . . . . . . . . . .
Bolt/Drill Sizes for Control Tube Repairs. . . . . . . . . .
Assessment Procedures. . . . . . . . . . . . . . . . . . . .
Essential Spare Parts. . . . . . . . . . . . . . . . . . . .
Spare and Repair Parts . . . . . . . . . . . . . . . . . . .
Weapons. . . . . . . . . . . . . . . . . . . . . . . . . . .
Substitute Fuels for JP-4 Fuel . . . . . . . . . . . . . . .
Fuels for the OH-58 Helicopter . . . . . . . . . . . . . . .
Substitute Commercial Fuels . . . . . . . . . . . . . . . .
Alternate and Expedient Fuel Blends. . . . . . . . . . . . .
Wire Table, Intercom System. . . . . . . . . . . . . . . . .
Wiring Table, UHF/AM Communication System. . . . . . . . . .
Wiring Table, VHF/AM Communication System. . . . . . . . . .
Wiring Table, VHF/FM Communication System. . . . . . . . . .
Wiring Table, Gyromagnetic Compass Set . . . . . . . . . . .
Wiring Table, ADF AN/APN-89
Radio Receiving Set AN/ARN-123(V)1, OH-58C . . . . . . . . . .
Wiring Table, Radar Altimeter AN/APN-209, OH-58C . . . . . .
Wiring Table, IFF, APX-72, OH-58A . . . . . . . . . . . . .
Wiring Table, IFF, APX-1OO, OH-58C . . . . . . . . . . . . .
Wiring Table, AN/APR-39 . . . . . . . . . . . . . . . . . . .
Page
4-44
4-47
4-50
5-3
6-3
7-4
8-6
9-4
9-18
11-2
11-3
11-7
11-16
11-18
11-27
11-37
12-3
13-3
13-11
13-11
15-7
D-2
D-3
D-5
D-7
D-8
D-9
D-10
F-3
F-5
F-7
F-9
F-11
F-13
F-15
F-17
F-19
F-20
F-22
vii

TM 55-1520-228-BD
HOW TO USE THIS MANUAL
This manual is developed to assist the soldier in a battlefield environment to make
assessment and repair of damage to the OH-58 helicopter which cannot, due to asset
availability or environmental factors, be repaired in the normal prescribed manner.
Within this technical manual, the word shall is used to indicate a mandatory
requirement.
The word should is used to indicate a nonmandatory but preferred
method of accomplishment. The word may is used to indicate an acceptable method of
accomplishment.
1.
Organization of the Manual.
This manual contains a general information chapter
(chapter 1), a general assessment chapter (chapter 2), and specific repair chapters
(chapters 4 thru 19). Chapter 3 is not used. It also contains five appendices.
References (Appendix A), special or fabricated tools (Appendix B),
expendable/durable supplies and materials list (Appendix C), substitute materials
and parts (Appendix D), and BDAR fixes authorized for training (Appendix E).
2.
Chapter 2 is used to assess the helicopter in general and references specific
chapters for detailed repair procedures of the major functional groups.
The major
functional groups correspond with the functional groups of the -23 series manuals
that are employed in routine repairs to the helicopter.
3.
Chapter 3 is not used in this manual. It would normally contain repairs for
equipment which does not fall under one of the standard helicopter functional groups.
4. Each functional group chapter is organized as follows:
a. Section I
- Introduction.
(1) Scope.
Purpose of the chapter.
(2) Assessment procedures. General assessment information for the repairs
covered therein.
(3) Repair procedure index.
b.
Section II - Repair Item.
A subsection is included for each repair item
covered in that functional group. It contains the following:
(1) General.
About the nature and cause of damage and repair.
(2) Item and trouble statement with:
(a) Limits given.
(b) Personnel and time required to effect repairs.
(c) Materials and tools needed.
(d) Procedural steps to accomplish the repair.
(3) If more than one method of repair can be used, the various options will
be included next.
NOTE
The first option is the preferred choice, the second option
is the next preferred, etc. Selection of the option should
be the most preferred method possible under the circumstances
and with the available materials and manpower.
viii

TM 55-1520-228-BD
HOW TO USE THIS MANUAL (Cont)
5. Finding Repairs in this Manual.
a. When the damage is obvious and known,
find the functional group chapter of
which the damaged item is a part. Turn to the repair procedure index, section I,
subparagraph c of each chapter to locate the item being repaired. Then turn to the
repair section and review each option to ascertain the appropriate fix. Read the
entire section for the option, then effect the repairs following the procedures
given.
b. When the damage is hidden and/or unknown, follow the overall assessment proce-
dures provided in chapter 2, and follow the procedures and directions provided.
6. Preparation.
a. Each mechanic/technician shall have read chapters 1 and 2 and become familiar
with the repairs and layout of the manual prior to attempting to accomplish BDAR
repairs.
b. All warnings, cautions, and safety precautions shall be followed, inasmuch as
possible, at all times during BDAR procedures so as not to further damage and/or
jeopardize either personnel or the equipment during or subsequent to the BDAR
action.
Ensure all documentation is completed as directed in this manual and by
local command.
7. Expendable/Durable Supplies and Materials.
a. Each fix or repair option contains a short listing of materials and tools con-
sidered basic to the repair. It is important to note that the expendable materials
listed usually cover a wide range for any one item.
Example:
MATERIALS/TOOLS REQUIRED:
● Drill with Bit
● Sheet Metal (items 131-142, Appx C)
● Rivets (items 98-115, Appx C)
In this example, sheet metal covers the range of items 131 thru 142 in Appendix C.
This means that, depending on the circumstances and location of the fix, any one of
these metals could be used.
Likewise any one of the rivets, items 98 thru 115, may
be used to attach the patch plate depending on the application.
b. One of the key points concerning successful BDAR repairs is flexibility. The
users of this manual should strive to use the items on hand, provided a safe repair
is made.
The stringent requirements of normal maintenance may be lifted.
ix/(x-Blank)