technical manual intermediate maintenance ...technical manual operators, aviation unit, and aviation...

T M 5 5 - 1 5 2 0 - 2 4 4 - B D

TECHNICAL MANUAL

OPERATORS, AVIATION UNIT,AND AVIATION

INTERMEDIATE MAINTENANCE

FOR

HELICOPTER,ATTACK

A H - 1 E1520-01-192-2478

AH-1 F1520-01-168-4260

A H - 1 P1520-01-168-4259

C H A P T E R 1 . G E N E R A L I N F O R M A T I O N

CHAPTER 2. ASSESSING BATTLEFIELD DAMAGE

C H A P T E R 3 . G E N E R A L R E P A I R

C H A P T E R 4 . A I R F R A M E

C H A P T E R 5 . A L I G H T I N G G E A R

CHAPTER 6 . POWER PLANT INSTALLATION

C H A P T E R 7 . R O T O R S

CHAPTER 8 . DRIVE TRAIN SYSTEM

C H A P T E R 9 . H Y D R A U L I C S Y S T E M S

CHAPTER 10. INSTRUMENT SYSTEMS

CHAPTER 11. ELECTRICAL & AVIONICS SYSTEMS

CHAPTER 12. FUEL SYSTEM

CHAPTER 13. FL IGHT CONTROLS SYSTEM

CHAPTER 14. UTIL ITY SYSTEMS

CHAPTER 15. ENVIRONMENTAL CONTROL SYSTEM

CHAPTER 16. MISSION EQUIPMENT

CHAPTER 17. EMERGENCY EQUIPMENT

A P P E N D I X A R E F E R E N C E S

APPENDIX B SPECIAL OR FABRICATED TOOLS

APPENDIX C EXPENDABLE/DURABLE SUPPLIES & MATERIALS

APPENDIX D SUBSTITUTE MATERIALS/PARTS

APPENDIX E BDAR TRAINING PROCEDURES

A P P E N D I X F A V I O N I C S C O N F I G U R A T I O N S

H E A D Q U A R T E R S , D E P A R T M E N T O F T H E26 NOVEMBER 1990

A R M Y

TM 55-1520-244-BD

WARNING DATA

Personnel performing operations, procedures, and practices which are included or implied in this technical manualshall observe the general following warnings. Disregard of these warnings can cause serious injury or death.

FLIGHT SAFETY

The standards contained herein allow aircraft to be flown with battle damage substantially in excess of peacetimelimits. Under no circumstances shall this manual be used entirely or in part for peacetime maintenance of theaircraft. Assessment of aircraft battle damage requires extreme care and diligence and strict adherence to the in-structions and standards contained in this manual. If at any stage of damage assessment the assessor believesthat oversights or errors have been made, the assessment shall be stopped at that point and repeated from thebeginning. Under no circumstances shall the requirements of this manual be waived or circumvented without theexpress approval of the commander or his designated representative.

EXPLOSIVES

Battle damaged areas should be inspected for unexploded ordnance before attempting repairs. Disposal of unex-ploded 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 ex-posure to personnel or property in the event of accidental firing. Personnel shall remain clear of hazardous area.

CANOPY REMOVAL SYSTEM

Ground safety pins must be installed in pilot and gunner arming/firing handles of canopy removal system when-ever the helicopter is on the ground.

CLEANING SOLVENTS

Cleaning solvents may be flammable and toxic. Use only in well-ventilated areas. Avoid inhalation of vapor andskin contact. Do not use solvents near open flame or in areas where very high temperatures prevail. Solvent flashpoint 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.

a

TM 55-1520-244-BD

HIGH VOLTAGE

is used in equipment.

DEATH ON CONTACTmay result if personnel fail to observe safety precautions.

Never work on electronic equipment unless there is another person nearbv who isfamiliar with the operation and hazards of the equipment and who is competent inadministering first aid. When the technician is aided by operators, he must warnthem about dangerous areas.

Whenever the nature of the operation permits, keep one hand away from the equipmentas 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 maycause death under adverse conditions. For Artificial Respiration, refer to FM 21-11.

LIFTING

Lifting or moving heavy equipment incorrectly can cause serious injury. Do not tryto lift or move more than 50 pounds by yourself. Bend legs while lifting. Do notsupport heavy weight with your back. Always use assistants during lifting opera-tions. Use guide ropes to move hanging assemblies. Lack of attention or being inan improper position during lifting operations can result in serious injury. Payclose attention to movements of assemblies being lifted. Do not stand under liftedassembly or in a position where you could be pinned against another object. Watchyour footing.

b

TM 55-1520-244-BD

ELECTROLYTE

Battery Electrolyte (Potassium Hydroxide) is corrosive. Wear rubber gloves, apron,and face shield when handling leaking batteries. If potassium hydroxide is spilledon clothing or other material, wash immediately with clean water. If spilled onpersonnel, immediately start flushing the affected area with clean water. Continuewashing until medical assistance arrives.

EXTERNAL STORES

Prior to any helicopter maintenance functions that require external stores beremoved, JETTISON cartridge shall be removed. To prevent injury to personneland damage to equipment, remove jettison cartridges from stores ejection deviceprior to placing helicopter in a hangar.

All ground safety pins must be removed before flight. Failure to do so will preventemergency jettison of stores.

FIRE EXTINGUISHER

Exposure to high concentrations of monobromotrifluoromethane (CF3BR) extinguishingagent or decomposition products should be avoided. The liquid should not be allowedto come into contact with the skin, as it may cause frost bite or low temperatureburns.

FUELING AND FUEL REPAIRS

When refueling helicopter, the refueling vehicle must be parked a minimum of 20 feetfrom the helicopter. Before starting the fueling operation, always insert fuelingnozzle grounding cable of fuel truck into GROUND HERE receptacle. Refer to FM10-68. When defueling, turn off all electrical switches and disconnect externalpower from the helicopter. The helicopter must be electrically grounded prior todefueling.

Fuel line and tank repairs often involve handling of highlyMishandling can result in serious injury or death.

GROUNDING HELICOPTER

flammable material.

The helicopter should be electrically grounded when parked to dissipate staticelectricity. Turn off all power switches before making electrical connections ordisconnections.

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 ordeath may occur. Be sure to open all drains and vents before beginning disassembly.

c

TM 55-1520-244-BD

HYDRAULIC FLUID

Prolonged contact with liquid or mist can irritate eyes and skin. Wear rubber gloves when handling liquid. Aftercontact with skin, immediately wash contacted area with soap and water. If liquid contacts eyes, flush immediatelywith clear water. If liquid is swallowed, do not induce vomiting. Get immediate medical attention. If prolonged ex-posure with mist is likely, wear an appropriate respirator. When fluid is decomposed by heating, toxic gases arereleased.

N O I S E

Sound pressure levels in and around this aircraft during operating conditions exceed the Surgeon General’s hear-ing conservation criteria, as defined in TB MED 501. Hearing protection devices such as aviator helmet or earplugs are required to be worn.

SANDING DUST

Sanding on reinforced laminated glass produces fine dust that may cause skin and lung irritations. Observe neces-sary protective measures.

TOXIC POISONS

Turbine fuels, lubricating oils, and adhesives contain additives which are poisonous and readily absorbed throughthe skin. Do not allow them to remain on skin longer than necessary. Wear protective equipment.

d

TM 55-1520-228-BD

LASER LIGHT

You can be blinded if you look into a laser beam when you are not wearing lasersafety goggles. Never aim the laser range finder (LRF) at personnel.

If laser beam reflects from a flat, mirror-like surface, it can blind you unless youare wearing laser safety goggles.

RADIOACTIVE MATERIALS

contain radioactive materials. If suchunsealed, avoid personal contact. Use

Self-luminous dials and ignition units mayan instrument or unit is broken or becomesforceps 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). Repairshall conform to requirements in AR 385-11.

e/(f blank)

TM 55-1520-244-BD

Technical Manual HEADQUARTERSDEPARTMENT OF THE ARMY

No. 55-1520-244-BD WASHINGTON, D. C., 26 November 1990

TECHNICAL MANUAL

OPERATORS, AVIATION UNIT, AND AVIATION INTERMEDIATE MAINTENANCE

BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR

FOR

HELlCOPTER, ATTACK

AH-1E 1520-01-192-2478AH-1F 1520-01-168-4260AH-1P 1520-01-168-4259

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTSYou can help improve this manual. If you find any mistake or if you know of a way to im-prove the procedure, please let us know. Mail your letter or DA Form 2028 (RecommendedChanges to Publications and Blank Forms) directly to: Commander, U.S. Army AviationSystems Command, ATTN: AMSAV-MC, 4300 Goodfellow Blvd., St. Louis, MO 63120-1798.A reply will be provided to you.

CHAPTER 1-

Section I.Section Il.Section Ill.

CHAPTER 2-

Section I.Section II.

CHAPTER 3-

CHAPTER 4-

Section I.Section Il.

CHAPTER 5-


CHAPTER 6-

Section I.Section Il.Section Ill.

TABLE OF CONTENTS

Page

HOW TO USE THIS MANUAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GENERAL INFORMATION

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Standards and Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Tasks and Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ASSESSING BATTLEFIELD DAMAGE

Introduction . . . . . . . . . . .General Fault Assessment Table

GENERAL REPAIRS . . . . . . . .

AIRFRAME

Introduction . . . . . . . . . . .Airframe Repairs . . . . . . . . .

ALIGHTING GEAR

Introduction . . . . . . . . . . .Skid Tube . . . . . . . . . . . .

POWER PLANT INSTALLATION

Introduction . . . . . . . . . . .Oil Tanks . . . . . . . . . . . . .Oil Pressure Indicator/Transmitter

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

x

1-11-31-5

2-12-3

3-1

4-14-36

5-15-4

6-16-16-10

i

TM 55-1520-244-BD

TABLE OF CONTENTS (Cont)

Page

Section IV. Fuel Filter. . . . . . . . . . . . . . . . . . . . . . . . .Section V. Fuel Control and Accessory Gearbox . . . . . . . . . . . . .Section VI. Emergency Engine Start. . . . . . . . . . . . . . . . . . .

CHAPTER 7 - ROTORS

Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .Section II. Main Rotor Hub and Blade. . . . . . . . . . . . . . . . . .Section III. Tail Rotor System.. . . . . . . . . . . . . . . . . . . . .

CHAPTER 8 - DRIVE TRAIN SYSTEM

Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .Section II. Transmission. . . . . . . . . . . . . . . . . . . . . . . .Section III. Tail Rotor Driveshaft. . . . . . . . . . . . . . . . . . . .

CHAPTER 9 - HYDRAULIC SYSTEMS

Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .Section II. Hoses. . . . . . . . . . . . . . . . . . . . . . . . . . . .Section III. Metal Tubing. . . . . . . . . . . . . . . . . . . . . . . .Section IV. Hydraulic Components . . . . . . . . . . . . . . . . . . . .Section V. Hydraulic System Isolation . . . . . . . . . . . . . . . . .Section VI. O-Ring, Packing, and Gaskets . . . . . . . . . . . . . . . .Section VII. Hydraulic Fluid Substitutions. . . . . . . . . . . . . . . .

CHAPTER 10 - INSTRUMENT SYSTEM.. . . . . . . . . . . . . . . . . . . . .

CHAPTER 11 - ELECTRICAL AND AVIONICS SYSTEM

Section I. Introduction. . . . . . . . . . . . . . . . . . . . . . . .Section II. Wire and Cable Splicing. . . . . . . . . . . . . . . . . . .Section III. Connector Repair. . . . . . . . . . . . . . . . . . . . . .Section IV. Overcurrent Protection Devices . . . . . . . . . . . . . . .Section V. Bus Bars . .Section VI. Power RelaysSection VII. Antennas . .Section VIII. Electrical

CHAPTER 12 - FUEL SYSTEM

Section I. Introduction

1 1 - 11 1 - 611-2411-2511-3011-3411-4611-50Wire Insulation

Section II. Lines and HosesSection III. Fuel Cells . .Section IV. Fuel Boost Pumps Section V. Fuel Filters . . .

6-146-146-17

7-17-17-19

8-18-18-14

9-19-119-159-219-239-309-31

10-1

12-11 2 - 112-712-2312-23

i i

TM 55-1520-244-BD

TABLE OF CONTENTS (Cont)

CHAPTER 13 -


CHAPTER 14 -

CHAPTER 15 -

Section I.Section II.Section III.Section IV.

CHAPTER 16-

Section I.Section II.Section III.Section IV.

CHAPTER 17 -

APPENDIX A -APPENDIX B -APPENDIX C -APPENDIX D -APPENDIX E -APPENDIX F -GLOSSARY . . .INDEX . . . .

G L O S - 1INDEX-1

Figure

1-11-21-34-14-24-34-44-54-64-74-84-9

FLIGHT CONTROL SYSTEM

Introduction.. . . . . . . . . . . . . . . . . . . . . . . . . . Flight Control Tubes. . . . . .. . . . . . . . . . . . . . . . . . . . . . . .

UTILITY SYSTEMS . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .

ENVIRONMENTAL CONTROL SYSTEM

Introduction. . . . . . . . . . . . . . . . . . . . . . . .Environmental Control Unit (ECU) . . . . . . . . . . . . . .Ducting. . . . . . . . . . . . . . . . . . . . ....Bleed Airlines. . . . . . . . . . . . . . . . . . . . . . .

MISSION EQUIPMENT

Introduction. . . . . . . . . . . . . . . . . . . . .Wiring. . . . . . . . . . . . . . . . . . . . . . . . . .Hydraulics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air Data Subsystem. . . . . . . . . . . . . . . . . . . . . . . . .

EMERGENCY EQUIPMENT. . . . . . . .. . . . . . . . . . . . . . . . . .

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SPECIAL OR FABRICATED TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . EXPENDABLE/DURABLE SUPPLIES AND MATERIALS . . . . . . . . . . . . .SUBSTITUTE MATERIALS/PARTS. . . . . . . . . . . . . . . . . . . . . . . . .BDAR TRAINING PROCEDURES. . . . . . . . . . . . . . . . . . . . . . . . . .AVIONICS CONFIGURATION. . . . . . . . . . . . ..

Page

13-113-5

14-1

15-115-115-615-9

16-116-316-516-5

17-1

A-1B-1C-1D-1E-1F-1

LIST OF ILLUSTRATIONS

Title

DA Form 2408-13. . . . . . . . . . . . . . . . . . . . . . DA Form 2408-18. . . . . . . . . . . . . . . . . . .. . . . . . Damage Assessment Markings (Sheet 1 of 3). . . . . . . . . .Aircraft Zones. . . . . . . . . . . . . . . . . . . . . . . . DA Form 2404. . . . . . . . . . . . . . . . . . . . Measuring Cap or Longeron Damage . . . . . . . . . . . . . .Damaged Cross Section . . . . . . . . . . . . . . . . . . .Measuring Skin Panel Damage . . . . . . . . . . . . . . . . .Measuring Damage in Floors or Decks . . . . . . . . . . . .Measuring Damage in Honeycomb Panels . . . . . . . . . . . .Airframe Reference Lines . . . . . . . . . . . . . . . . . .Primary Structural Caps L/H . . . . . . . . . . . . . . . .

Page

1-61-71-84-24-74-94-94-114-114-124-154-16

iii

TM 55-1520-244-BD

LIST OF ILLUSTRATIONS (Cont)

Figure

4-104-114-124-134-144-154-164-174-184-194-204-214-224-234-244-254-264-274-284-294-304-314-324-33

4-34

4-35

4-36

4-37

4-384-394-40

4-415-15-25-35-4

iv

Title

Structural WebsL/H . . . . . . . . . . . . . . . . . . . .Primary Structural Caps R/H . . . . . . . . . . . . . . . .Structural Webs R/H . . . . . . . . . . . . . . . . . . . .Fuselage Box Beam Panels. . . . . . . . . . . . . . . . . .L/H Fuselage Beam . . . . . . . . . . . . . . . . . . . . .R/HFuselage Beam . . . . . . . . . . . . . . . . . . . . .Upper Panels. . . . . . . . . . . . . . . . . . . . . . , .Lower Panels. . . . . . . . . . . . . . . . . . . . . . . .Pylon Support . . . . . . . . . . . . . . . . . . . . . . .Post Member Consisting of Three Elements . . . . . . . , . .Tail Boom . . . . . . . . . . . . . . . . . . . . . . . . .Fin. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Skin Panel Damage WL Versus Frame Spacing S. . . . . . . . .Typical Skin Panel and Frame Damage . . . . . . . . . . . .AH-1S Left Wing - Skins Removed . . . . . . . . . . . . . .Typical Former Repair. . . . . . . . . . . . . . . . . . . .Cut and Drill Former Repair. . . . . . . . . . . . . . . . .Cutout in Damaged Skin . . . . . . . . . . . . . . . . .Stringer/Stiffener Repair. . . . . . . . . . . . . . . . . .Expedient Cap/Longeron Repair . . . . . . . . . . . . . . .Repair of Damage Bulkhead Flange . . . . . . . . . . . . . .Typical Combination Repair (angle view). . . . . . . . . . .Typical Combination Repair (side view) . . . . . . . . . . .Damaged Honeycomb Core Panel - Small Damage to One Skin andand Core. . . . . . . . . . . . . . . . . . . . . . . . . .Damaged Honeycomb Core Panel, 2-8 Inch Damage - One Skinand Core. . . . . . . . . . . . . . . . . . . . . . . . . .Repaired Honeycomb Core Panel, 2-8 Inch Damage - One Skinand Core. . . . . . . . . . . . . . . . . . . . . . . . . .Damaged Honeycomb Core Panel, 2-8 Inch Damage - Both Skinsand Core. . . . . . . . . . . . . . . . . . . . . . . . . .Repaired Honeycomb Core Panel, 2-8 Inch Damage - Both Skinsand Core. . . . . . . . . . . . . . . . . . . . . . . . . .Damage Repair, Accessible One Side Only. . . . . . . . . . .Fabrication of Patch Plate. . . . . . . . . . . . ..O . .Repair of Honeycomb Core Panel - Damage Over 8 Inches - BothSkins and Core. . . . . . . . . . . . . . . . . . . . . . .Fracture Lacing with Safety Wire . . . . . . . . . . . . . .Landing Gear and Support Installation. . . . . . . . . . . .Skid Tube Damage Zones . . . . . . . . . . . . . . . . . . .Skid Shoe Repair. . . . . . . . . . . . . . . . . . . . . .Clamp Repair. . . . . . . . . . . . . . . . . . . . . . . .Fabricated Clamp. . . . . . . . . . . . . . . . . . . . . .Engine, Right-Hand View. . . . . . . . . . . . . . . . . . .Engine, Left-HandView . . . . . . . . . . . . . . . . . . .Oil Tank. . . . . . . . . . . . . . . . . . . . . . . . . .Wood Plug. . . . . . . . . . . . . . . . . . . . . . . . . .Sealant Repair. . . . . . . . . . . . . . . . . . . . . . .Screw, Washer, and Gasket.. . . . . . . . . . . . . . . .,

Page

4-164-174-174-184-194-204-214-224-264-284-304-314-344-344-364-394-404-424-424-444-464-474-48

4-50

4-50

4-51

4-52

4-524-544-54

5-56-16-26-36-46-56-6

6-26-36-56-76-86-8

TM 55-1520-244-BD

Figure

6-76-8

6-11

6-96-10

6-126-137-17-27-37-47-57-67-77-87-97-107-117-127-137-147-157-168-18-28-38-4

8-5

8-6

8-7

8-88-98-10

8-118-12


Title

Hose Assembly, Sealant, Nut, and Bolt . . . . . . . . . . . . . . .Sheet Metal with Sealant or Blind Rivets . . . . . . . . . . . . . .Oil Pressure Transmitter . . . . . . . . . . . . . . . . . . . . .Torque Pressure Transmitter . . . . . . . . . . . . . . . . . . .Fuel Control Assembly and Accessory Gearbox Assembly . . . . . . .Tach Generator Removal . . . . . . . . . . . . . . . . . . . .External Power Plug . . . . . . . . . . . . . . . . . . . . . .Main Rotor System . . . . . . . . . . . . . . . . . . . . . . .Application of Tape . . . . . . . . . . . . . . . . . . . . . . .Marking Work Area . . . . . . . . . . . . . . . . . . . . . . .Application of Adhesive and Position of PatchBalance Adjustment for Patches (K747 Blade) (Sheet 1 or 2) . . . . . . . . .Maximum Allowable Repairable Damage to Rotor Blade . . . . . . . .Typical Double Plug Patch Repair . . . . . . . . . . . . . . . . .Marking Work Area . . . . . . . . . . . . . . . . . . . . . . .Removal of Damage Skin . . . . . . . . . . . . . . . . .Setting Router Depth . . . . . . . . . . . . . . . . . . . . . .Insertion of Patch . . . . . . . . . . . . . . . . . . . . . . .Drag Brace . . . . . . . . . . . . . . . . . . . . . . . . . .Tail Rotor installation . . . . . . . . . . . . . . . . . . . . . .Tail Rotor Blade-Area Authorized for Patch-Type Repair . . . . . . . .Aluminum Skin Patch . . . . . . . . . . . . . . . . . . . . . .Skin Patch Tape Cover . . . . . . . . . . . . . . . . . . . . .Drive Train (Typical) . . . . . . . . . . . . . . . . . . . . . .Transmission Oil Pressure Switch and Transmitter Repair . . . . . . . .Transmission Assembly, Unaltered . . . . . . . . . . . . . . . . .Altered Configuration (Transmission Oil System) BypassingFilter and Outlet Hose . . . . . . . . . . . . . . . . . . . . . .Altered Configuration (Transmission Oil System) BypassingOil Filter . . . . . . . . . . . . . . . . . . . . . . . . . . .Altered Configuration (Transmission Oil System) BypassingFilter and lnlet Hose . . . . . . . . . . . . . . . . . . . . . .Altered Configuration (Transmission Oil System) SubstitutingHose at Sump Outlet (Sheet 1 of 2)Damage Passing Through Center of Shaft . . . . . . . . . . . . . . .Damage Not Passing Through Center of Shaft . . . . . . . . . . . .Balance Restoring Repair for Damage Not Passing ThroughCenter of Shaft . . . . . . . . . . . . . . . . . . . . . . . .Y and S Graph . . . . . . . . . . . . . . . . . . . . . . . . .Area and Diameter Graph . . . . . . . . . . . . . . . . . . . .

Page

6-96-116-126-136-156-166-187-27-57-77-77-97-117-127-137-147-157-167-187-207-217-217-228-28-58-6

8-7

8-9

8-11

8-128-168-17

8-188-198-19

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TM 55-1520-244-BD

LIST OF ILLUSTRATIONS (Cent)

Figure

8-138-148-159-19-29-39-49-59-69-79-89-99-109-119-129-139-149-159-169-179-189-199-209-2111-111-211-311-411-511-611-711-811-911-1011-1111-1211-1311-1411-1511-1611-1711-1811-1911-2011-2111-2211-2311-2411-25

vi

Title

Damaged Shaft; Petals Straightened Smooth. . . . . . . . . .Repaired Shaft. . . . . . . . . . . . . . . . . . . . . . .Shaft Area (in*) vs. Number of Rivets. . . . . . . . . . . .Hydraulic System Schematic (Sheet 1 of 2). . . . . . . . . .Hydraulic System - SYSTEM No. 2 (Sheet 1 of 2) . . . . . . .Hydraulic System - SYSTEM No. 1. . . . . . . . . . . . . . .Hydraulic System - Armament (Sheet 1 of 2) . . . . . . . . .Emergency (Electric Motor Driven) Hydraulic System . . . . .Two-Part Fitting. . . . . . . . . . . . . . . . . . . . . .Four-Part Fitting. . . . . . . . . . . . . . . . . . . . . .Installation of MS Hose Fitting Socket and Sleeve. . . . . .Assembly of MS Fitting . . . . . . . . . . . . . . . . . . .Using Tube Cutter. . . . . . . . . . . . . . . . . . . . . .Properly Burred Tubing . . . . . . . . . . . . . . . . . . .Damaged Tube Sections . . . . . . . . . . . . . . . . . . .MS Tube Fitting Installation . . . . . . . . . . . . . . . .Completed Tubing Installation. . . . . . . . . . . . . . . .Completed High Pressure Hose Substitution. . . . . . . . . .MS Union Installation . . . . . . . . . . . . . . . . . . .Lock-Out Valve Assembly. . . . . . . . . . . . . . . . . . .Hydraulic System Unaltered . . . . . . . . . . . . . . . . .Hydraulic System, Isolating No. 1 System . . . . . . . . . .Hydraulic Pump and Drive Pad . . . . . . . . . . . . . . . .Hydraulic System, Isolating No. 2 System . . . . . . . . . .Circuit Identification.. . . . . . . . . . . . . . . . . .Crimp Splice . . . . . . . . . . . . . . . . . . . . . . .Splicing with Terminal Lug Barrel. . . . . . . . . . . . . .Twist Wire Splice . . . . . . . . . . . . . . . . . . . . .Replacement Section; Twist Wire Splice . . . . . . . . . . .Metal Casing Splice. . . . . . . . . . . . . . . . . . . . .Replacement Section; Terminal Lug Repair . . . . . . . . . .Ram Wire Repair . . . . . . . . . . . . . . . . . . . . . .Shielded Cable Repair Preparation. . . . . . . . . . . . . .Shielded Cable Splice Preparation. . . . . . . . . . . . . .Completed Shielded Cable Splice. . . . . . . . . . . . . . .Sheath Connector Splice. . . . . . . . . . . . . . . . . . .Pigtail Sheath Splice . . . . . . . . . . . . . . . . . . .Substitute Shielded Braid Splice . . . . . . . . . . . . . .Shield Terminator Repair Preparation . . . . . . . . . . . .Shield Terminator Repair. . . . . . . . . . . . . . . . . .Component Bypass. . . . . . . . . . . . . . . . . . . . . .Connector Pin and Socket. . . . . . . . . . . . . . . . . .Damaged Connector and Wire . . . . . . . . . . . . . . . . .Typical Original Circuit Breaker Connection. . . . . . . . .Construction of Fuse Link. . . . . . . . . . . . . . . . . .Typical Fuses. . . . . . . . . . . . . . . . . . . . . . . .Fabricated Fuse, Type A... . . . . . . . . . . . . . . . .Fabricated Fuse, Type B. . . . . . . . . . . . . . . . . . .Splicing Bus Bars. . . . . . . . . . . . . . . . . . . . . .

Page

8-218-228-239 - 29 - 49 - 69 - 79-99-129-129-149-149-169-169-189-199-199-209-219-229-249-259-279-2911-311-811-911-1111-1111-1211-1311-1411-1511-1611-1611-1711-1911-2011-2211-2211-2311-2411-2511-2611-2811-2911-3011-3011-32

TM 55-1520-244-BD


Title PageFigure

11-2611-2711-2811-2911-3011-3111-3211-3311-3411-3511-3611-3711-3811-3911-4012-112-212-312-412-512-612-712-812-912-1012-1112-1212-1312-1412-1512-1612-1712-1812-1912-2013-113-213-313-413-513-613-713-813-913-1013-11

15-115-2

Lengthening Bus Bars. . . . . . . . . . . . . . . . . . . .Battery Cell Layout. . . . . . . . . . . . . . . . . . . . .Block Diagram Power Relay, Check and Test. . . . . . . . . .AH-1 PROD Battery Compartment, Forward View (Sheet 1 of 2) .AH-1 PROD Battery Compartment, Side View (Sheet 1 of 2). . .AH-1 ECAS and MC Battery Compartment (Sheet 1 of 2). . . . .AH-1 ECAS and MC Battery Compartment (Sheet 1 of 3). . . . .Block Diagram, Typical Power Relays. . . . . . . . . . . . .Jumper Wire Fabrication. . . . . . . . . . . . . . . . . . .Frequency vs. Wavelength . . . . . . . . . . . . . . . . . .Preparation of Coax . . . . . . . . . . . . . . . . . . . .Installation of Field Expedient Antenna. . . . . . . . . . .Pigtail Termination for Shielded Wire. . . . . . . . . . . .Heat Shrinkable Tape. . . . . . . . . . . . . . . . . . . .Insulation Repair with Sleeving. . . . . . . . . . . . . . .Fuel System . . . . . . . . . . . . . . . . . . . . . . . .Use of String Bead. . . . . . . . . . . . . . . . . . . . .Long Replacement Tube Section. . . . . . . . . . . . . . . .Repair of Small Hole in Tube . . . . . . . . . . . . . . . .Expedient Repair of Damaged Hose . . . . . . . . . . . . . .Replacement of Damaged Hose Section. . . . . . . . . . . . .Inlet Line to Fuel Control. . . . . . . . . . . . . . . . .Emergency Mechanical Clamp Repair . . . . . . . . . . . . .Rubber Repair Plug Assembly . . . . . . . . . . . . . . . .Plug Modification for Three Plane (Corner) Repair. . . . . .Aft Cell Isolation Access Panels . . . . . . . . . . . . . .Crossover Line Flange Template . . . . . . . . . . . . . . .Blocked Off Crossover Line . . . . . . . . . . . . . . . . .Fuel Manifold. . . . . . . . . . . . . . . . . . . . . . . .Blocked Off Fuel Cell. . . . . . . . . . . . . . . . . . . .Floor Baffle Assembly . . . . . . . . . . . . . . . . . . .Fuel Quality Probe; Fuel Inlet . . . . . . . . . . . . . . .External Fuel Filter Assembly. . . . . . . . . . . . . . . .External Fuel Filter. . . . . . . . . . . . . . . . . . . .Bypassing External Fuel Filter . . . . . . . . . . . . . . .Flight Controls . . . . . . . . . . . . . . . . . . . . . .Stability and Control Augmentation System (SCAS) . . . . . .Collective Flight Controls . . . . . . . . . . . . . . . . .Cyclic, Lateral Controls . . . . . . . . . . . . . . . . . .Cyclic, Fore and Aft Controls . . . . . . . . . . . . . . .Tail Rotor Controls. . . . . . . . . . . . . . . . . . . . .Control Tube Splice. . . . . . . . . . . . . . . . . . . . .Control Rod with Bearing and Clevis Assemblies . . . . . . .Flattened End of Fabricated Flight Control . . . . . . . . .Corner Rounding on Fabricated Flight Control . . . . . . . .Bell Crank or Lever Assembly Connection of FabricatedFlight Control . . . . . . . . . . . . . . . . . . . . . . .Environmental Control System . . . . . . . . . . . . . . .ECU Housing. . . . . . . . . . . . . . . . . . . . . . . . .

11-3211-3311-3411-3611-3811-4011-4211-4511-4511-4711-4711-4911-5011-5211-5212-212-512-512-612-812-812-1012-1112-1312-1412-1612-1712-1812-1912-2212-2412-2512-2612-2812-2913-213-313-613-713-813-913-1213-1413-1513-15

13-1515-215-4

vii

TM 55-1520-244-BD

Figure

15-315-415-515-616-116-216-3F-1

F-2F-3

F-4F-5F-6F-7F-8F-9F-10F-11F-12F-13F-14F-15

Table No.

2-12-24-14-24-3

5-16-17-17-28-18-29-111-111-211-311-411-512-1

viii


Title

Ducts, Flexible Plastic . . . . . . . . . . . . . . . . . .Ducts, Rigid Plastic. . . . . . . . . . . . . . . . . . . .Bleed Air Lines. . . . . . . . . . . . . . . . . . . . . . .Bleed Line Patch Repair. . . . . . . . . . . . . . . . . . .Turret Gun Brake Toggle (ECAS and MC). . . . . . . . . . . .Outboard Wing Stores Pylon.. . . . . . . . . . . . . . . .ADS Pneumatic Lines. . . . . . . . . . . . . . . . . . . . .UHF Command Communication System AN/ARC-116() or AN/ARC-164(Sheet l of 2) . . . . . . . . . . . . . . . . . . . . . . .VHF Command Communication System AN/ARC-115 (Sheet 1 of 2) .VHF Command Commnunication System AN/ARC-115 or AN/ARC-186(Sheet l of 2) . . . . . . . . . . . . . . . . . . . . . . .FM Liaison Communication System AN/ARC-114 (Sheet 1 of 3). .FM Liaison Communication System AN/ARC-114A (Sheet 1 of 3) .Gyromagnetic Compass System AN/ASN-43 (Sheet 1 of 2) . . . .Automatic Direction Finder AN/ARN-89B (Sheet 1 of 2) . . . .VOR/MB/GS Receiving Set Radio AN/ARN-123(V)3 (Sheet 1 of 3).Doppler Navigation System AN/ASN-128 (MC) (Sheet 1 of 2) . .Radar Altimeter System AN/APN-209 (Sheet 1 of 2) . . . . . .IFF System AN/APX-72 (Sheet 1 of 2). . . . . . . . . . . . .IFF System AN/APX-100(V) (Sheet 1 of 2). . . . . . . . . . .Radar Warning System AN/APR-39(V)1 (Sheet 1 of 2). . . . . .Countermeasures Set AN/ALQ-136 (MC) (Sheet 1 of 2) . . . . .Countermeasures Set AN/ALQ-144(V) (MC) (Sheet 1 of 2). . . .

LIST OF TABLES

Title

General Decision Logic . . . . . . . . . . . . . . . . . . .Assessment Table. . . . . . . . . . . . . . . . . . . . . .Structure Damage Assessment Procedures . . . . . . . . . . .Allowable Fuselage Damage Limits-Condition 1, Fuselage Caps.Allowable Tail Boom Damage Limits-Condition 1, Tail BoomLongerons. . . . . . . . . . . . . . . . . . . . . . . . . .Alighting Gear Assessment Procedures . . . . . . . . . . . .Power Plant Assessment Procedures. . . . . . . . . . . . . .Rotor Assessment Procedures. . . . . . . . . . . . . . . . .Plug Patch Kits. . . . . . . . . . . . . . . . . . . . . . .Drive Train Assessment Procedures. . . . . . . . . . . . . .Shaft Area (in2) vs. Number of Rivets. . . . . . . . . . . .Hydraulic System Assessment Procedures . . . . . . . . . . .Electrical and Avionics Assessment Procedures. . . . . . . .Function and Designation Letters . . . . . . . . . . . . . .Unshielded Crimp Splice Application. . . . . . . . . . . . .Shielded Cable Repair . . . . . . . . . . . . . . . . . . .Fuse Link Strands. . . . . . . . . . . . . . . . . . . . . .Fuel System Assessment Procedures. . . . . . . . . . . . . .

Page

15-715-815-1015-1116-416-616-7

F-1F-5

F-7F-9F-14F-19F-23F-27F-37F-42F-45F-50F-54F-57F-59

Page

2-22-34-44-24

4-325-26-47-37-118-38-239-1011-211-311-711-1511-2712-3

TM 55-1520-244-BD

Table No.

13-113-213-314-115-116-1D-1D-2D-3D-4D-5D-6D-7D-8D-9F-1F-2F-3F-4

F-5F-6F-7F-8F-9F-10F-11F-12F-13F-14F-15F-16

LIST OF TABLES (Cont)

Title

Flight Control System Assessment Procedures. . . . . . . . .Control Tube Dimensions. . . . . . . . . . . . . . . . . . .Bolt/Drill Sizes for Control Tube Repairs. . . . . . . . . .Utility Systems Assessment Procedures. . . . . . . . . . . .Environmental Control System Assessment Procedures . . . . .Mission Equipment Assessment Procedures. . . . . . . . . . .Spare and Repair Parts . . . . . . . . . . . . . . . . . . .Armament Parts. . . . . . . . . . . . . . . . . . . . . . .Packing Reference and Temperature Guides Chart . . . . . . .Substitute U.S. Fuels. . . . . . . . . . . . . . . . . . . .Substitute Foreign Fuels.. . . . . . . . . . . . . . . . .Substitute Commercial Fuels. . . . . . . . . . . . . . . . .Alternate and Expedient Fuel Blends. . . . . . . . . . . . .Substitute Lubricants and Hydraulic Fluids . . . . . . . . .Metal Substitution Chart.. . . . . . . . . . . . . . . . .UHF AN/ARC-1160, Wire Chart . . . . . . . . . . . . . . . .UHF AN/ARC-1640, Wire Chart . . . . . . . . . . . . . . . .VHF AN/ARC-1150, Wire Chart . . . . . . . . . . . . . . . .VHF Command Commnunication System AN/ARC-l15 or AN/ARC-186,Wire Chart. . . . . . . . . . . . . . . . . . . . . . . . .FM AN/ARC-1140, Wire Chart (with KY-28) PROD and ECAS . . .FM AN/ARC-1140, Wire Chart (with KY-28) MC. . . . . . . . .AN/ASN-43,Wire Chart . . . . . . . . . . . . . . . . . . . .AN/ARN-89B, Wire Chart, ADF. . . . . . . . . . . . . . . . .AN/ARN-123(V)3, Wire Chart, MC, P, E . . . . . . . . . . . .AN/ASN-128,Wire Chart... . . . . . . . . . . . . . . . .AN/APN-209,Wire Chart... . . . . . . . . . . . . . . . .AN/APX-72,Wire Chart . . . . . . . . . . . . . . . . . . . .AN/APX-lOO,Wire Chart... . . . . . . . . . . . . . . . .AN/APR-39,Wire Chart . . . . . . . . . . . . . . . . . . . .AN/ALQ-136,Wire Chart... . . . . . . . . . . . . . . . .AN/ALQ-144,Wire Chart... . . . . . . . . . . . . . . . .

Page

13-413-1013-1114-215-316-3D-2D-10D-12D-17D-18D-19D-20D-21D-24F-4F-4F-6

F-8F-12F-17F-21F-25F-30F-39F-44F-47F-52F-56F-58F-61

ix

TM 55-1520-244-BD

HOW TO USE THIS MANUAL

This manual is developed to assist the soldier in a battlefield environment make assessment and repair ofdamage to the AH-1 attack helicopter which cannot, due to asset availability or environmental factors, berepaired in the normal prescribed manner. Within this technical manual, the word shall is used to indicate a man-datory requirement. The word should is used to indicate a nonmandatory but preferred method of accomplish-ment. 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 generalassessment chapter (chapter 2), and specific repair chapters (chapters 4 thru 17). Chapter 3 is not used. It alsocontains five appendixes.

2. Chapter 2 is used to assess the helicopter in general and references specific chapters for detailed repair pro-cedures 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 underone 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. Itcontains 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. Selec-tion of the option should be the most preferred method possible under the circumstancesand with the available materials and manpower.

x

TM 55-1520-244-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 apart. Turn to the repair procedure index, section I, subparagraph 3 of each chapter to locate the item beingrepaired. Then turn to the repair section and review each option to ascertain the appropriate fix. Read the entiresection for the option, then effect the repairs following the procedures given.

b. When the damage is hidden or unknown, follow the overall assessment procedures provided in chapter 2,and follow the procedures and directions provided.

6. Preparation.

a. Each mechanic/technician shall read chapters 1 and 2 and shall be familiar with the repairs and layout ofthe manual prior to attempting to accomplish BDAR repairs.

b. All warnings, cautions, and standard safety precautions shall be followed, inasmuch as possible, at alltimes during BDAR procedures so as not to further damage or jeopardize either personnel or the equipmentduring or subsequent to the BDAR action. Ensure all documentation is completed as directed in this manual andby local command.

7. Expendable/Durable Supplies and Materials.

a. Each fix or repair option contains a short listing of materials and tools considered basic to the repair. It is im-portant 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, App. C)• Rivets (items 98-115, App. C)

In this example, sheet metal covers the range of items 131 thru 142 listed 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 oneof 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 shouldstrive to use the items on hand, provided a safe repair is made. The stringent requirements of normal main-tenance may be lifted.

xi/(xii blank)

TM 55-1520-244-BD

CHAPTER 1

GENERAL INFORMATION

BDAR FIXES SHALL BE USED ONLY IN COMBAT OR FOR TRAININGAT THE DISCRETION OF THE COMMANDER.

(AUTHORIZED TRAINING FIXES ARE LISTED IN APPENDIX E.)IN EITHER CASE, DAMAGES SHALL BE REPAIRED BY STANDARD

PROCEDURES AS SOON AS PRACTICABLE.

Section I.

1-1. PURPOSE. The purpose of BattlefieldDamage Assessment and Repair (BDAR) is to quicklyreturn the disabled helicopter to the operational com-mander by expediently fixing, bypassing, or jury-rig-ging components to restore the minimum essentialsystems required for the support of the specific com-bat mission or for self-recovery. These repairs will betemporary and may not restore full performancecapability. Standard repair will be completed as soonas practical.

1-2. SCOPE.

a. This technical manual (TM) describes BDARprocedures applicable to AH-1S attack helicopterseries and these procedures are to be used by crew,operators, aviation unit maintenance (AVUM) teams,and aviation intermediate maintenance (AVIM) sup-port teams.

b. Standard repair techniques for the attackhelicopter are included in other technical manualswhich are referenced in Appendix A of this TM.Details of these procedures are not duplicated inwhole in this TM. If the repairs are more than onepage in length, the repairs may only be referenced inappropriate chapter.

c. All possible types of combat damage andfailure modes cannot be predicted, nor are all effec-tive field expedient repairs known. This TM providesguidelines for assessing and repairing battlefield

INTRODUCTION

failures of helicopters and is not intended to be a com-plete catalog of all possible emergency repairs. Therepairs described here will serve as guidelines andwill stimulate the experienced mechanic/operator todevise repairs as needed to rapidly return equipmentto operation in a combat situation.

d. The direct replacement of a piece of equip-ment by its spare, even under battlefield conditions, isnot a BDAR fix and may not be covered is in this TM.A standard procedure should be performed inpreference to a BDAR fix when time and spares areavailable.

1-3. APPLICATION.

a. The procedures in this manual are designedfor battlefield environments and should be used insituations where standard maintenance proceduresare impractical. These procedures are not meant toreplace standard maintenance practices, but rather tosupplement them strictly in a battlefield environment.Standard maintenance procedures will provide themost effective means of returning damaged equip-ment to ready status provided that adequate time,replacement parts, necessary tools, andtrained/qualified repair persons are available. BDARprocedures are only authorized for use in an emergen-cy situation in a battlefield environment, and only atthe direction of the commander. They are not to becontinued after the equipment is out of the battle en-vironment.

1-1

TM 55-1520-244-BD

b. BDAR techniques are not limited tosimple restoration of minimum functionalcombat capability. If full functionalcapability can be restored expedientlywith a limited expenditure of time andassets, it will be accomplished.

c. Some of the special techniques inthis manual, if applied, may result inshortened life or in further damage tomajor components of the helicopter. Thecommander must decide whether the riskof having one less helicopter availablefor combat outweighs the risk ofapplying the potentially destructiveexpedient repair technique. Each tech-nique gives appropriate warnings,cautions, and lists systems limitationscaused by this action.

1-4. DEFINITIONS.

a. Battlefield Damage. Any incidentsuch as combat damage, random failures,operator errors, accidents, and wear-outfailures which occur on the battlefieldand which prevent the helicopter fromaccomplishing its mission.

b. Repair or Fix. Any expedientaction that returns a damaged part orassembly to a full or an acceptablydegraded operating condition, including:

(1) Short cuts in parts removal orinstallation.

(2) Installation of componentsfrom other equipment that can bemodified to fit or interchange withcomponents on the damaged equipment.

(3) Repair using parts that servea noncritical function elsewhere onthe same equipment for the purpose ofrestoring a critical function.

(4) Bypassing of noncritical com-ponents in order to restore basic func-tional capability.

(5) Expeditious cannibalizationprocedures.

(6) Fabrication of parts from kitsor readily available materials.

(7) Jury-rigging.

(8) Use of substitute materials.

c. Damage Assessment. A procedure torapidly determine what is damaged,whether it is repairable, what assetsare required to make the repair, who cando the repair (e.g., crew, maintenanceteam or maintenance support team), andwhere the repair should be made. Theassessment procedure includes thefollowing steps:

(1) Determine if the repair can bedeferred, or if it must be done.

(2) Isolate the damaged areas andcomponents.

(3) Determinemust be fixed.

(4) Prescribe

(5) Determineponents, materials,

which components

fixes.

if parts or com-and tools are

available.

(6) Estimateskill required.

(7) Estimatehours) required to

the manpower and

the total time (clockmake the repair.

(8) Establish the priority of thefixes.

(9) Decide where the fix shall beperformed.

(10) Decide if recovery or evacua-tion is necessary and to what location.

d. Fully Mission Capable (FMC). Thehelicopter can perform all its combatmissions. To be FMC, the helicopter mustbe complete and fully operable with nofaults listed in the aircraft inspectionand maintenance record as prescribed inDA PAM 738-751.

1-2

TM 55-1520-244-BD

e. Combat Capable.. Equipment meets the mini-mum functional combat capability requirements. (Seeparagraph 1-8.)

f. Combat Emergency Capable. The equipmentmeets the needs for specific tactical missions; how-ever, all systems are not functional. Also, additionaldamage due to the nature of an expedient repair mayoccur to the equipment if it is used. The commandermust decide if these limitations are acceptable for thatspecific emergency situation.

g.. Cannibalization or Controlled Exchange.Throughout this manual, cannibalization and control-led exchange are used interchangeably to mean theremoval of an item of materiel from one piece ofequipment for immediate use in another. Generallythe rules for cannibalization/controlled exchangeprovided in TM55-1500-328-25, as modified by localauthority, will prevail.

h. Evacuation. A combat service support func-tion which involves the movement of recoveredhelicopters from a main supply route, maintenancecollection point, or maintenance activity to highercategories of maintenance. The materiel may bereturned to the user, to the supply system for reissue,or to property disposal activities.

i. Recovery. The retrieval of immobile, inopera-tive, or abandoned helicopter from the battlefield orimmediate vicinity, and its movement to a main-tenance collection point, the main supply route, or amaintenance activity for disposition, repair, or evacua-tion.

j. Self-Recovery. The ability of the helicopter tofly at reduced airspeed and altitude from the bat-tlefield, or immediate vicinity to a maintenance collec-tion point, main supply route, or maintenance activityfor disposition, repair, or evacuation.

k. Maintenance Co llection Point. A pointoperated by AVIM unit for the collection of equipmentfor repair.

l. Maintenance Support Team (MST). A team ofAVIM mechanics and technical specialists who aretrained in assessing battlefield damage and fieldrepair procedures.

m. Maintenance Team (MT). Helicopter crewchief or AVUM mechanics/technicians who are trainedin assessing battlefield damage and field repair proce-dures.

1-5. QUALITY DEFICIENCY REPORT/EQUIP-MENT IMPROVEMENT RECOMMENDATION(QDR/EIR). If your helicopter and equipment needsimprovement, let us know. Send us an EIR. You, theuser, are the only one who can tell us what you don’tlike about your equipment. Let us know why you don’tlike the design. Put it on an SF 368 (Quality Deficien-cy Report). Mail it to Commander, U.S. Army AviationSystems Command, ATTN: AMSAV-QRF, 4300Goodfellow Boulevard, St. Louis, MO 63120-1798.We’ll send you a reply.

Section Il. STANDARDS AND PRACTICES

1-6. BDAR CHARACTERISTICS. BDAR capa- practices. In a combat emergency situation, greaterbility requires simplicity, speed, and effectiveness. risks are sometimes necessary and acceptable.Some BDAR procedures include repair techniques Refer to Appendix I of FM 1-500 for additional informa-that violate standard peacetime maintenance tion concerning BDAR concepts.

1-3

TM 55-1520-244-BD

1-7. WAIVER OF PRECAUTIONS. Under combatconditions, BDAR may be performed on helicopterswhich are in flight or which are under power while onthe ground. While some of these BDAR actions mayrequire waiving of safety precautions, the cautions toprotect personnel life should not be overlooked.Other similar precautions may be waived at the discre-tion of the commander. BDAR fixes maybe requiredin a chemically toxic environment or under other ad-verse battlefield conditions with severe limitations inpersonnel, facilities, equipment, and materials. Perfor-mance of repair tasks may be necessary while wear-ing protective gear. Decontamination procedures aredescribed in FM 3-5.

1-8. OPERATING CHARACTERISTICS. Thismanual covers expedient repairs for the helicopterand its components. It is entirely possible that in acombat situation, the helicopter having undergoneone or more of these repairs may suffer degradationof its normal operating characteristics (e.g., reducedspeed, reduced load capability, reduced range, etc.),and still be able to carry out all or parts of an as-signed mission. The minimum functional combatcapability (M FCC) criteria is as follows:

NOTE

These criteria may be waived for recoveryor to meet tactical situation demands other-wise.

a. Flight Capability for Self-Recovery.

(1) Must have power delivered to main and tailrotor at minimum acceptable limits.

(2) Lift capability for crew members.

(3) Flight controls at minimum function level ac-ceptable for flight.

NOTE

Careful consideration shall be given to theoperation of the Identify Friend or FOE(IFF), Mode 4, avionics system. Failure ofthe IFF or failure to properly communicatewith area air defense command prior to lift-off could result in an attack from friendlyforces due to mistaken identity.

(4) Instruments/avionics as required to meetmission needs.

b. Flight Capability for Mission Completion.

(1) Sufficient power delivered to main and tailrotor to accommodate lift capability for helicoptercrew and cargo.

(2) No fuel leaks which will curtail the intendedlength of flight.

(3) No degradation of any component/systemwhich will end in failure and curtailment of intendedmission.

(4) Communications. Must have intercomcommunications within aircraft and at least two tacti-cal receiver-transmitter (R-T) units operating at fullcapability.

1-9. TRAINING.

a. BDAR by its nature involves fixes, bypasses,or jury-rigging, which is outside authorized standardrepairs, and may degrade the inherent safety of thehelicopter. Therefore, BDAR actions are not intendedto supplement, or replace standard maintenance prac-tices during peacetime, nor should they be employedindiscriminately to facilitate training.

b. Repairs described in this manual, which canbe appropriately accomplished in order to providetraining, are listed in Appendix E and are highlightedin each chapter’s repair procedure index. Thetrainable repair in the index will be blocked in.

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TM 55-1520-244-BD

Section Ill. TASKS AND RESPONSIBILITIES

1-10. TAGGING/IDENTIFYING BDAR REPAIRS.

a. All damage will be identified on aircraft inspec-tion and maintenance record, DA Form 2408-13 andDA PAM 2408-18, per DA PAM 738-751. Refer toFigures 1-1 and 1-2.

b. Recording of BDAR repairs and the use ofstatus symbols, as defined in DA PAM 738-750, willbe completed as soon as practical to indicate anylimitations and restrictions or required standardrepairs.

c. In addition to recording all damage, the areadamaged will be marked on aircraft or componentpart using damage assessment markings as shownFigure 1-3.

d. Status Symbols. Status symbols used in

in

aircraft logbooks to record defects are defined below.

(1) Red “X.” A red “X” shows that a defectexists and the aircraft is unsafe for flight.

(2) Circled red “X.” A red “X’ inside a redcircle indicates a limiting defect. The aircraft may beflown under specific limits as directed by higherauthority, or as directed locally until corrective actionis taken.

(3) Red horizontal dash (-).

(a) This symbol indicates an inspection, spe-cial inspection, component replacement, maintenanceoperational check, or test flight is needed. The sym-bol is also used to indicate that a normal modificationwork order (MWO) is overdue.

(b) This symbol also shows that the condi-tion of the equipment is unknown. A potentiallydangerous condition may exist. The condition will be

(4) Red diagonal (/). This symbol indicates adefect exists that is not serious enough to ground theaircraft.

e. Maintenance of Forms. Instructions for themaintenance of forms, records, and reports are listedin DA PAM 738-751. When battle damage repair(BDR) becomes necessary, the procedures in DAPAM 738-750 will apply. Refer to Figures 1-1 and 1-2for examples.

(1) In block 17 of DA Form 2408-13, list thefault.

(2) In block 16 of DA Form 2408-13, enter thestatus symbol.

(3) In block 18 of DA Form 2408-13, enter thecorrective action taken.

(4) The individual completing the repair willsign the form in block 19 opposite the first line of theaction taken, and will place his last name initial overthe status symbol in block 16.

f. Temporary Repair. If the repair is temporary,take the following additional action:

(1) In block 18 of DA Form 2408-13, enter thecorrective action and a statement that the repair istemporary. Then make an entry in DA Form 2408-14,block b. The entry will be a duplicate of the entry inblock 17 of DA Form 2408-13 to include a statementthat a temporary repair has been made.

(2) If the temporary repair limits the capabilityof the aircraft, the following entry will be made on DAForm 2408-13:

(a) Place a circled red “X” in bolck 16.

corrected as soon as possible.

1-5

TM

55-1520-244-BD

Fig

ure

1

-1.

DA

Fo

rm 2408-13

1-6

TM 55-1520-244-BD

Figure 1-2.DA

Form 2408-18

1-7

TM 55-1520-244-BD

MEANINGS

TO INDICATE DAMAGE HAS BEEN ASSESSED AND EVALUATED:

Draw a circle around the damage.

TO INDICATE NO BDAR REPAIR REQUIRED:

Write “OK” inside the circle.

TO INDICATE STRUCTURAL REPAIRS ARE REQUIRED:

Draw a second line about 1/4 to 1/2way around the initial circle thendraw slashes or crosshatch betweenthe two circular lines.

STRINGER REPAIR: Place an X to theleft and right of the circle.

FRAME REPAIR: Place an X above andbelow the circle.

TO INDICATE DAMAGE TO SYSTEMS REQUIRING REPAIRS:

Draw a series of ’’curly cue” lines about1/4 to 1/2 way around the initial circle.

TO INDICATE REPAIR INSTRUCTIONS:

For internal damage - draw a dashedcircle around the repair instructions.

For external damage - write repairinstructions but do NOT enclosewith a circle.

MARKINGS

REPAIRINSTRUCTIONS PARTIAL

Figure 1-3. Damage Assessment Markings (Sheet 1 of 3)

1-8

TM 55-1520-244-BD

WRITTEN INSTRUCTIONS MEANING

See me - print name & See assessor or whoever has signed written instructionsrank. (Signature) for additional information. -

Names of parts to Where compound damage occurs, the names or abbreviation:be repaired, (item, of specific items can be written adjacent to the damageskin, stringer. to clarify repair instructions.

Full A full strength repair is required.

Partial Partial strength repair required in accordance withspecific aircraft BDAR manual.

OK No repairs required - damage is within acceptable limit:for battle conditions.

? Continual assessment or reinspection is required aftereach sortie.

Instruction markings for system are in two parts:

(1) Repair instruction markings and meanings are shown on this sheet and areused to indicate repair actions required.

(2) System Identification - When known, identify the system using markingsshown on sheet 3 of this figure.

MARKINGS MEANING

Fix Repair the damaged system in accordance with approvedstandard BDAR techniques for type of system, item,high pressure, low pressure, etc.

Cap Terminate or block the system to prevent leakage.

Repl Replace damaged part - repairs not acceptable.

OK No repairs required.

Tag Repair instructions are written on tags tied to indivi-dual damaged lines/components.


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System identification markings are primarily abbreviations of the system.

MARKINGS SYSTEM/MEANING

Sys Damage to unknown system.

Fuel Fuel

Hyd Hydraulic

HP High Pressure

LP Low Pressure

Elect Electrical

AV Avionics

Flt Cent Flight Control

Main Rotor Main Rotor Group

Tail Rotor Tail Rotor Group

Air Pneumatic

Air Cond Air Conditioning

BL Air Bleed Air System

BLC Boundary Layer Control

N2 Nitrogen

O2 Oxygen

Eng Contr Engine Control

Pow Tr Power Train

EJ Ejection

NOTE

More than one identification marking may be used to describethe system (e.g., HP, Hyd).


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TM 55-1520-244-BD

(b) State the limitation inblock 17.

(3) If the temporary repairrequires an inspection at intervals,list the required inspection on DA Form2408-18.

(a) Enter item to be inspectedin block 5.

(b) List the applicable TM inblock 6.

(c) State the frequency of theinspection in block 7.

1-11. REPORTS. All required writtenreports for BDAR fixes are found in DAPAM 738-751. If communication capa-bility is damaged, the aircraftcommander should approach the nearestfriendly radio and make his reportif possible. The report shouldinclude these essentials:

a. Aircraft damage (out-of-action orfunction partially impared).

b. Location of aircraft.

c. Defense status.

d. Mobility.

e. Personnel report.

f. Current and anticipated hostileaction.

Anticipated BDAR fixes and repairtime.

1-11/(1-12 Blank)

TM 55-1520-244-BD

CHAPTER 2

ASSESSING BATTLEFIELD DAMAGE




Section I. INTRODUCTION

2-1. SCOPE.

a. This chapter provides guidelines for use inassessing battlefield damage to the AH-1 E/F/P attackhelicopter. It directs you to an expedient BDAR fix orto the standard system fix toTM 55-1520-236-23 if anexpedient BDAR repair does not exist. Generaldecision logic chart, Table 2-1, assists in BDAR dis-cussions.

b. Each chapter will have a specific fault assess-ment table for each functional group and this flowchart will direct you to specific BDAR fixes for andwithin the functional group.

c. Use the following guidelines to find and fix sus-tained damage or suspected damage to your helicop-ter. Keep in mind that damage can be sustained whileon the ground or in flight. The helicopter location canhave a considerable effect on the assessment. Thefollowing appraisal shall be accomplished,

(1) If possible and if time permits, inspect, andcheck the helicopter using operator’s checklist (CL),operator’s manual (–1 O), and other records and formskept in aircraft log book. At the same time be lookingfor obvious damage to aircraft.

(3) If you find a problem, determine its effecton helicopter’s mobility, and capability.

(4) If you cannot fix the problem with standardfixes, then apply this TM and use general and specificassessment tables, charts, and BDAR action.

(5) If the damage does not affect aircraft’sflying status, the aircraft or flight commander willdecide whether to fix or defer fix, and whether to con-tinue or to start a mission.

(6) If damage does affect flight status, do oneof the following:

(a) Replace damaged part with a service-able part.

(b) Replace damaged part with suitable sub-stitute if it exists.

(c) Apply a BDAR fix.

(7) After repairing the damage, replace all lostfluids/lubricants. If one specified by aircraft TM is notavailable, refer to Appendix D for alternativematerials/parts.

(2) If applicable and possible, use standardtroubleshooting recommendations in –23 series TMs.

2-1

TM 55-1520-244-BD

Figure 2-1. General Decision Logic

2 - 2

TM 55-1520-244-BD

Section II. GENERAL FAULT ASSESSMENT TABLE

2-2. GENERAL FAULT ASSESSMENT. The BDAR assessment procedure will referAircraft assessment chart, Table 2-2, you to a guide fix in this manual, aguides you through the aircraft’s standard TM 55-1520-236-23 repair if itcapability so that all the necessary is feasible, or a higher AVIM level ofcapabilities are evaluated. If a fault repair if extent of damage, time con-is found, Table 2-2 (assessment table) straint, tooling requirements, repairdirects you to the chapter for the func- part or material, and any other necessarytional group which contains the fault. requirements are only available at a

higher level of maintenance.

Figure 2-2. Assessment Table 2-3

TM 55-1520-244-BD

Figure 2-2. Assessment Table (Cont)

2-4

TM 55-1520-244-BD

Figure 2-2. Assessment Table (Cent)2-5

TM 55-1520-244-BD

Figure 2-2. Assessment Table (Cent)

2-6

TM 55-1520-244-BD

Figure 2-2. Assessment Table (Cont)2-7

TM 55-1520-244-BD

Figure 2-2. Assessment Table (Cont)

2-8

2-9Figure 2-2.

CHPT 13

CHPT 15

CHPT 16

TM 55-1520-244-BD

TM 55-1520-244-BD

CHAPTER 3

GENERAL REPAIRS




No general repairs have been identified Chapters 4 thru 17 for functional groupfor this model helicopter. Proceed to assessment and repair procedures.

3-1/(3-2 Blank)

TM 55-1520-244-BD

CHAPTER 4

AIRFRAME

4-1.

a.




Section I. INTRODUCTION

SCOPE.

This chapter contains methods for assessingbattlefield damage to the primary structure of the -

AH-1 airframe, classification of damage, rules fordeferring repair, and expedient field fixes of battlefielddamaged airframe structures.

b. Aircraft structure is classified as primary andsecondary structure.

(1) The primary structure is the basic structurewhich holds the aircraft together. Any serious damageto any element of the primary structure will restrict thecombat capability of the aircraft. The primary struc-tures for each major airframe subassembly aredefined throughout this chapter.

(2) Secondary structures are mounted on theprimary structure. No amount of structural damage tosecondary structures will restrict combat capabilityfrom a structural safety point of view; however, secon-dary structure may be required for aerodynamicreasons or to accomplish or support mission functions.

4-2. ASSESSMENT PROCEDURES. The battle-field structural damage assessment consists of twosteps: an initial assessment, and a detailed assess-ment. The initial assessment is a quick visual assess-ment to decide whether or not a detailed assessment

should be made. A detailed assessment involves theidentification of all damage to primary structural ele-ments, possibly some cleanup and measurement ofthe damage and of the damaged elements. Thisprocess requires damage measurement and deter-mination of the corresponding damage limits. An over-all view of all the aircraft zones used in damageassessment is shown in Figure 4-1.

NOTE

The standards contained herein allowaircraft to be flown with battle damage sub-stantially in excess of peacetime limits.Under no circumstances shall this manualbe used wholly or in part for peacetimemaintenance of the aircraft. Assessment ofaircraft battle damage requires extremecare and diligence and strict adherence tothe instructions and standards contained inthis manual. If at any stage of damage as-sessment the assessor believes that over-sights or errors have been made, theassessment shall be stopped at that pointand repeated from the beginning. Underno circumstances shall the requirements ofthis manual be waived or circumventedwithout the express approval of the com-mander or his designated representative.

4-1

TM 55-1520-244-BD

Figure 4-1. Aircraft Zones

4-2

● Battle damaged areas should be inspectedfor unexploded ordnance before attempt-ing repairs. Disposal of unexplodedordnance should be accomplished byqualified EOD personnel.

● Loaded weapons, or weapons beingloaded or unloaded, shall be pointed in adirection which offers the least exposure topersonnel or property in the event of ac-cidental firing. Personnel shall remainclear of hazardous area of all loadedweapons.

● Ground safety pins must be installed inpilot and gunner arming/firing handles ofcanopy removal system whenever thehelicopter is on the ground. Pins should beinstalled by crew.

a. Initial Assessment. Refer to Table 4-1. To per-form an initial assessment, the assessor must be ac-quainted with structural damage modes and theprimary structure. He shall be capable of differentiat-ing between primary and secondary structure, and hemust understand the function of primary structural ele-ments. The initial assessment consists of a visual in-spection of primary structure. The assessordetermines if any primary caps, webs, or panels aredamaged or fractured and decides whether–

(1) The damage appears to be deferrable;

(2) A detailed assessment can be made andthe damage can be repaired by BDAR techniqueswithin the time available to return the aircraft to ser-vice in the ongoing battle;

TM 55-1520-244-BD

(3) An adequate assessment can be made andthe damage can be repaired by BDAR techniques toenable the aircraft to self-recover;

(4) A detailed assessment cannot be made orthe damage cannot be repaired by BDAR techniqueswithin the available time; or

(5) The aircraft is damaged beyond repair, andits disposition shall be arranged (e.g., recovery, canni-balization, or destruction).

b. Detailed Assessment.

(1) Access to damaged structure. Locate alldamage to airframe primary structure. Removeaccess panels, covers, and fairings in the damagedarea. Remove aircraft components as required to in-spect the structure. Use the location of entrance andexit wounds and the estimates of projectile paths todetermine the areas where damage may be presentand access to interior inspection will be needed. If anarea of structure suspected of being damaged cannotbe reached by other means, cut small inspectionholes in the exterior skin. Then inspect internal mem-bers with an inspection light and mirror.

NOTE

Inspection holes cut in the exterior skin ifleft unrepaired will have to be treated asdamaged structure in the damage evalua-tion. Allow for access to the areas immedi-ately next to the area where damage isknown to have occurred. This will ensurethat damage caused by stray particles anddislodged sections of material can befound. All significant damage to theairframe primary structure must be lo-cated. Small damage can be critical tosome components.

4-3

Table 4-1.

TM 55-1520-244-BD

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TM 55-1520-244-BD

(2) Inspecting for cracks.

(a) Impact cracks. Cracks maybe caused by projectile impact orpenetration. They may also be caused asa direct result of blast pressures.Battle damaged elements carrying reducedloads will place more severe loads onsurviving members and may also producecracks. When cracks are a result ofthese last two factors, they may occurin regions away from the site of theprimary damage.

(b) Projectile damage sitecracks. Cracks will primarily be foundat the site of the projectile damage.Holes, spans, and gouges caused byricochets and embedded particles willoften have cracks associated with them.These may be large and visible orhairline and microscopic. Small cracksmay be as critical as large cracksbecause they may grow rapidly undercontinued loading, particularly whenlocated at the edge of a hole.

(c) Airframe structure cracks.Locate all cracks in airframe primarystructure. At each damage site, inspectthe area for cracks. Use inspectionaids such as magnifying glasses or dyepenetrant to locate small cracks.Cracks may not go all the way throughthe material, so it is necessary toinspect both sides. When a structureshows signs of overstress, it is vitalto inspect for cracks around fasteners.

(d) High explosive incendiary(HEI) explosion cracks. For aircraftdamaged by an HEI strike, inspect all ofthe structure in the area of the explo-sion. Aircraft may have been flown with

(3) Inspecting for structuralchanges.

(a) Structural changes.Inspect for structural changes when theaircraft has taken an HEI hit or theaircraft has flown with primary struc-ture damaged or missing. Inspect boththe damaged structure and the surroundingundamaged area for evidence of buckling,crippling, and misalignment. This typeof damage is usually revealed by kinksor wrinkling and “oil canning” of skinpanels. Sheared, pulled-through, andmissing fasteners are also indicationsof structural changes.

(b) Buckling, crippling, andmisalignment. Structural changes in theform of buckling, crippling, and misa-lignment can happen as a result of blastpressures. These could be associatedwith a HEI attack or as a result of theoverstress placed on a member. Suchmembers may have to carry the load ofanother member which has been broken orcrippled by projectile damage. Thistype of damage can be critical to thestructural performance of a member andmay also cause interference with mecha-nical moving components which may bindor jam. This is especially true whenthe member has to support compressionloads. A stringer that has been damagedcan continue to support some tension;for example, but may be completely inef-fective in compression.

(c) Twisting or bowing.Examine the component for alignment andsigns of twisting or bowing. Use astraight edge to inspect these con-ditions.

major structural battle damage or failure. (4) Inspecting for embeddedIt is vital to inspect for cracks in all projectiles and fragments.areas to which additional load may havebeen distributed.

4-5

TM 55-1520-244-BD

(a) Embedded projectile. Theeffect of an embedded projectile orfragment in a tension member can be assevere as that of a hole or crack of thesame size. The embedded object createsan interruption in the structural sec-tion. Since it is difficult to detect,it must be assumed that the projectilehas nearly gone through the structure.

(b) Embedded projectile inspec-tion. Inspect for embedded projectilesand fragments when either of the follow-ing conditions occur:

1 The aircraft has sufferedHEI damage.

2 Inspection of the aircraftindicates that a solid projectile hasnot exited the aircraft, has brokenapart, or has created shrapnel bystriking internal components.

(C) Projectile path deter-mination. The determination of projec-tile paths will aid in identifyinginternal structures that may containembedded projectiles or fragments.Inspect all structures in the regionusing a bright light and magnifyingglass. Clearly mark embedded objectsand record them on DA Form 2404, Figure4-2.

(5) Inspecting for fire damage.

(a) Armor piercing incendiary(API) and HEI fire damage. The API andHEI threats include the possibility offire damage. These threats have a fire-starting capability if flammablematerials are present.

(b) Fire effects. Some firesmay not adversely effect metal airframestructures. When aluminum is exposed totemperatures above 300°F (149°C) for aprolonged period, the temper andstrength of the material will bereduced.

(c) Initial fire damage evi-dence. The first signs of possible firedamage will be a discoloration of thestructure. Any discoloration indicatesthat the member has been exposed to hightemperature. Conduct a hardness test todetermine if the temper of the materialhas changed. Such tests should be con-ducted in accordance with standard prac-tices. If a hardness test showsheat damage, record the information onDA Form 2408 and clearly mark themember.

(6) Detecting substructural damagein adjoining areas.

(a) Secondary damage. When theairframe has been subjected to severeoverstress, members undamaged by projec-tiles may bend or buckle. This might becaused by explosive blast or maneuveringloads imposed on damaged structures.Sometimes this secondary damage willoccur in a region away from the primaryarea of damage. The airframe near theprojectile damage should be inspectedfor evidence of secondary damage.

(b) Secondary damage indicators.Inspect the skin for creases, wrinkles,and dents. Inspect fasteners forchipped or flaked paint, looseness, andserviceability. These conditions aresigns of damage to structure. Open orremove access panels and doors, deter-mine whether the frame is warped, andinspect the interior members for cracksand structural changes. Clearly markand record all damage.

(7) Inspecting for broken andmissing fasteners.

(a) Fastener damage or loss.Some fasteners join parts together in anassembly, and some join one structuralmember to another. Sheared, pulled-through, torn-out, elongated fastenerholes, and the damage or loss of fas-teners can severely weaken the soundnessof a structure.

4-6

TM 55-1520-244-BD

Figure 4-2. DA Form 2404

4-7

TM 55-1520-244-BD

(b) Riveted and bolted joints.Inspect all riveted and bolted jointsnear the battle damage. Look forsheared, pulled-through, torn-outfasteners, and elongated fastener holes.Carefully inspect members showing signsof structural change and for fastenerswith chipped or cracked paint. Wherepossible, inspect fasteners from bothsides. Clearly mark and record alldamaged fasteners on DA Form 2404.

(8) Inspecting for delamination.To verify suspected damage to honeycombstructures, use coin tapping method todetermine size and shape ofdisbonds/delaminations.

NOTE

Resonation of coin tapping on thestructure will determine hollow-ness or existence of delamination.

(9) Marking and recording damage.

(a) Damage recording. Accuraterecording of damage is an important partof battle damage assessment. Record alldetected damage on DA Form 2404. Deter-mine allowable damage limits. Establishan order of repair on DA Form 2404.Record individual areas of damage to asingle structural element separately onthe form. If a structural member ismassively damaged or severed, recordingindividual areas of damage isunnecessary.

(b) Damage diagrams. Show thelocation and extent of damage on copiesof the diagrams given in this chapter.The damage can be drawn by hand.Accurately locating damage on a diagramwill greatly help the damage assessmentprocedure.

(c) Marking damage. Mark thedamaged structure using grease pencil orpaint. Use the labeling scheme given inFigure 1-3.

CAUTION

Use of lead pencil in some areaswill cause corrosion.

1 Use a bright color tooutline each area of damage as it islocated and recorded on the DA Form2404. Attempt to make the outlinevisible from all angles.

2 Draw arrows on inside skinpanels, webs, and bulkheads to pointtoward areas of damage that are hidden.

c. Damage Measurement. If the assess-ment indicates that the damage should berepaired by BDAR or standard procedures,no damage measurement isnecessary. Damage measurement isrequired to determine if structuralrepair (other than cleanup) can bedeferred, or if self-recovery of thedamaged aircraft is feasible. Damagemeasurement may also be required if aBDAR repair does not restore originalstrength. Begin damage measurement withthe largest damage.

(1) Caps and longerons.

(a) The parameters involved inmeasuring damage to a cap or longeronare shown in Figure 4-3. The pertinentvalues are as follows:

CD = Depth of damage.CL = Length (width) of damage.A = CL x CD = area of damage.D = Distance between damages.

In Figure 4-4, the length of the flat-tened cross section shown is a+b.

If CD is the depth of the damage intothe flattened cross section, then CS Isthe length of the remaining effectivecross section still capable of support-ing load, and CS= (a+b)-CD. Alwaysmeasure CD.

4-8

TM 55-1520-244-BD

Figure4-3. Measuring Cap or Longeron Damage

Figure 4-4. Damaged Cross Section

4-9

TM 55-1520-244-BD

(b) Damage measurements applyafter cleanup and smoothing or afterBDAR has been accomplished; however, asa practical matter, measurements mustoften be taken before smoothing to makea decision on deferrability. Hence,when estimating damage limits beforecleanup and smoothing, make allowancefor the material that will be removed insmoothing. This applies particularly tocracks; the length of the crack must beincluded in the depth (CD) and length(CL) measurements. When measuringdamage, use the following procedures ifpossible:

1 Clean all damaged areasthoroughly. Use brushes and rags toremove dirt and film from small creviceswhere damage may be present.

2 Smooth all jagged andrough edges and be sure to cut out allradiated cracks. Use largest cornerradii possible in the cut-outs; avoidsharp corners.

3 Measure damage aftersmoothing or if measuring beforesmoothing, make allowance for thematerial which must be removed duringsmoothing.

4 Use a steel rule graduatedin tenths of an inch and measure eachdamage dimension to the next highertenth.

5 Include the size of thehole when measuring damage that extendsinto a fastener hole or lightening hole.

6 Record on DA Form 2404.

(2) Webs, panels, floors, anddecks.

across the damage, regardless of direc-tion and must include all radiatedcracks. “D” is the distance betweendamages. Take and record measurementsas described in paragraph 4-2.c(1) (b).

(b) Honeycomb sandwich struc-tures. Refer to Figure 4-7 for themeasurement of “WL” and “D.” If a pro-jectile hits a sandwich panel at anangle, the damages in the two skins maybe off-set and of different sizes.Measure the damage on the side with thelargest damage (usually the exit side),and make sure that the measurementincludes the damaged area on the otherside. “WL” is the largest dimensionacross the damage (both sides),regardless of direction, and mustinclude all radiated cracks. “D” is thedistance between damages. Take andrecord the measurements as previouslydescribed.

d. General Damage Limits.

(1) The allowable damage limitscorresponding to the damage measurementsof paragraph 4-2.c are designated for agiven condition as follows:

CD' = Allowable depth ofcap/longeron damage.

DL' = Allowable length (width) ofcap/longeron damage.

A' = Allowable area of damage.

D' = Minimum allowable distancebetween damages.

WL' = Allowable largest dimensionacross web/panel damage.

N = Minimum Damage Factor.

(a) Refer to Figures 4-5 and4-6 for the measurements of "WL" and"D." "WL" is the largest dimension

4-10

TM 55-1520-244-BD

Figure 4-5. Measuring Skin Panel Damage

Figure 4-6. Measuring Damage in Floors and Decks

4-11

TM 55-1520-244-BD

Figure 4-7. Measuring Damage in Honeycomb Panels

(2) Allowable damage limits areassociated with the conditions ofthe primary structural elements asdescribed below. A damage limit for agiven condition is a measure of theamount of damage that a structuralmember can sustain and still supportthe loads associated with the givencondition. These limits were developedfrom the aircraft manufacturer’s origi-nal engineering design calculations.

(3) Condition is an indicator ofthe residual capacity of a damaged struc-tural element to perform its function.Battlefield damaged structures or BDARrepairthree

fullyrestriunder

damages. Therefore, aircraft with struc-tural damage whether repaired or repairdeferred should be inspected after everyflight. The inspector should look forcrack growth, evidence of overstress,growth of allowable deformation, or thedevelopment of new cracks at other loca-tions.

(b) Condition 2. Self-recoverycapable. Self-recovery may be requiredto move a damaged aircraft to a repairsite or from one site to another, whentowing is not feasible. Self-recoveryis preferable to disassembly and boxingan aircraft for transportation. As time

ed structures are classified in permits, proceed as follows:conditions:

1 Mark all visible cracks(a) Condition 1. Aircraft and the extent of other structural

flight capable. No flight damage with chalk, grease pencil, paint,ctions; however, on a battlefield tape, or other available means so thatthe pressures of time and tactical any growth in the damage can be quickly

situations’, the assessment of structural recognized.damage may not have revealed all the

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TM 55-1520-244-BD

2 Perform any feasible on-site BDAR fixes as required for self-recovery.

(c) Condition 3. Structuraldamage not repairable by BDAR tech-niques, not self-recovery capable. Theairframe is so extensively damaged thatno useful or needed functions can berestored within the available time andresources. These aircraft will be:

1 recovered or evacuated toa facility with the resources to repairthe airframe,

2 used as a source of can-nibalized components, or

3 destroyed. This is a lastresort.

(d) These conditions apply tothe primary structure and should not beconfused with the mission capabilityclassifications. Mission capability isdependent on equipment condition.

(4) In a given condition if alldamages are equal to or less than thecorresponding allowable damage limitsand the distance between damages areequal to or greater than the correspond-ing minimal allowable limit, that is,

CD < CD'CL < CL'WL < WL'D > D '

the aircraft may be released for flightin that condition. Repair may bedeferred although some clean-up andsmoothing of the damage will be requiredas will inspection for damage growthafter every flight. Special con-sideration should be given to damageexposed to the airstream, particularlyto the effects of ram air, rain, and

petaling. Petals may vibrate in thepassing airflow, rapidly creating cracksin the supporting base metal. Largepieces of metal may peel off and damageother parts of the aircraft. Thedistance D between damage sites formost structures has a minimum requiredspacing. The spacing requirement isexpressed as a multiple factor (N) ofthe measured area of damage.

(a) The factor applies to thedamage actually measured not to themaximum damage limit for the structure.

(b) The factor applies to thelargest dimension of the largest damagebetween which separation is beingmeasured.

(c) The factor applies only ifthe dimensions of both damages, whenadded together, exceed the single damagelimit.

(5) Continuous members. Allowabledamage limits for caps, longerons, webs,floors, decks, and stiffness are giventhroughout this section as appropriate.

(6) Damaged fittings, attachments,and splices are classified as unservice-able and must be repaired, reinforced,or replaced if any of the followingconditions exist:

(a) Damage to the fitting hasremoved more than 20 percent of thestructural cross section at any onelocation.

(b) One or more fastenersconnecting the fitting to a continuousaircraft component are bent, sheared,stripped, or loose.

(c) The fitting shows signs ofoverstress or structural distortion.

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(7) Damage limits are calculatedon the basis of the AH-1S structuralanalysis and tend to be conservative.Assessors using damage limits to preparedamage assessments should consider themas guides and balance the damage limitsagainst the judgment resulting fromtheir own experience.

e. Fuselage Damage Assessment.

(1) General.

(a) The fuselage midsectionprimary basic structure consists of abox beam starting at FS 148.5 andextending to FS 300.68, Figure 4-8.Forward of the box beam (FS 148.5), twofuselage beams and cockpit floors extendforward to FS 61.25 to support the cock-pit and gun turret. The tail boomattaches to the fuselage at FS 300.68and extends to the fin which supportsthe tail rotor and the stinger (tailbumper).

(b) The fuselage box beam con-sists of 4 caps (Figures 4-9 and 4-11)connected vertically by the webs of thefuselage beams (Figures 4-10 and 4-12)and connected horizontally by the upperand lower panels (Figure 4-13). Bulk-head flanges act as spacers betweenthe caps, both vertically and horizon-tally, and should be treated as caps ina damage assessment. The bulkheads alsohold the shape of the aircraft anddistribute concentrated loads into thevertical panels and/or horizontalpanels. The concentrated loads includethe loads from the landing gear, pylon,wing attachments, elevator, tail rotor,fin, and tail bumper.

(2) Damage measurement.

(a) Reproduce Figures 4-14 to4-17 as required, and use to mark updamaged areas.

(b) Refer to Figures 4-9 to4-13 for definition and identificationof primary fuselage structural elements.

(c) Mark all detected damage onthe appropriate figure, and add remarksto clarify markings as described inparagraph 4-2.b(9).

(d) Refer to paragraph 4-2. cand for each damaged element, measurethe depth "CD" and the length (width)"CL" or "WL" of each damage. Count thenumber of damages and measure the "D"between damages. Start with the worstdamage. Record the values on DA Form2404 and compare therewith the allowabledamage limits given in this section.Select the set of allowable damagelimits which are next larger than themeasured damage, determine thecorresponding condition. Considerwhether damage could result in flightfailure of other elements. Attempt tovisualize what effect large defectionsof damaged member will have on adjacentstructure.

(e) Decide on whether repaircan be deferred or whether damage shouldbe fixed and what the condition ofdeferred or repaired damage would be.

(f) Determine the priority ofthe various required repairs based onrepair time, difficulty of repair,resources available, tactical situation,and need for the aircraft, etc. Thelongest repair time normally is giventhe highest priority and is mostcritical.

(g) Enter repair requirementson DA Forms 2404.

(3) Allowable fueslage damage

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Figure 4-8. Airframe Reference Lines

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Figure 4-9. Primary Structural Caps L/H

Figure 4-10. Structural Webs L/H

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Figure 4-11. Primary Structural Caps R/H

Figure 4-12. Structural Webs R/H

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Figure 4-13. Fuselage Box Beam Panels

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