ID07180066_-_Attachment_5_-_TM_1-1520-237-10.pdf

Section III CARGO HANDLING SYSTEMS

4.17 CARGO HOOK SYSTEM.

The system consists of a hook assembly (Figure 4-23) mounted on the lower fuselage, a control panel on the up-per console (Figure 2-7), a normal release button on each cyclic stick grip, one emergency release switch on each collective stick grip, and a firing key in the cabin for use by the crew chief. The system incorporates three modes of load release, an electrical circuit actuated from the cockpit, a manual release worked by the crewmember through a covered hatch in the cabin floor, and an emergency release system using an electrically-activated explosive charge.

4.17.1 Cargo Hook Stowage. The cargo hook shall be

maintained in the stowed position during periods of non-use. The cargo hook can be placed in a stowed position (Figure 4-23) by opening the cargo hook access cover in the cabin floor, and pulling the hook to the right and up.

When the hook is in the stowed position, the load beam rests on a spring-loaded latch assembly and is prevented from vibrating by a teflon bumper applying downward pressure on the load beam. To release the hook from its stowed position, downward pressure is placed on the latch assembly lever, retracting the latch from beneath the load beam, allowing the cargo hook to swing into operating po-sition.

4.17.2 Cargo Hook Control Panel. The CARGO

HOOK control panel (Figure 4-23), on the upper console, consists of anEMERG REL NORM , OPEN, SHORT test switch, aTEST light, CONTR CKPT or ALL station selector switch and anARMING , SAFE, ARMED switch.

Before the normal release (electrical) can operate, the ARMING switch must be atARMED to provide electrical power to the release switches. The pilot and copilot CARGO REL switches, on the cyclics, will release the load when theCONTR switch is atCKPT or ALL . The crewmember’sNORMAL RLSE switch will release the load when theCONTR switch is atALL . The EMERG REL switch andTEST light permits checking the emer-gency release circuit when atSHORT or OPEN. In both cases of testing, if the release circuit is good, theTEST light will go on when theHOOK EMER REL switch on pilot’s or copilot’s collective, or theEMER RLSE switch on the crewmember’s pendant, is pressed.

4.17.3 Crewmember’s Cargo Hook Control Pen-

dant. The crewmember’s cargo hook control pendant (Figure 4-24), in the aft cabin, provides the crew chief with an electrical release and jettison of an external load when the CARGO HOOK CONTR switch is placed toALL .

The NORMAL RLSE and EMER RLSE switches are covered by guards to prevent accidental activation. When the cover is raised the switch can be pressed. When not in use, the pendant is stowed in the stowage bag at the back of the pilot’s seat. Electrical power to operate the pendant is provided from the No. 2 dc primary bus through a circuit breaker, markedCARGO HOOK CONTR .

4.17.3.1 Normal Release. Normal release of external

cargo is done by pressing theCARGO REL switch on either cyclic stick grip or theCARGO HOOK NORMAL RLSE on the crewmember’s cargo hook pendant, after placing the CARGO HOOK ARMING switch to ARMED . A light on the advisory panel will go on, indi-cating HOOK ARMED . This informs the pilot that elec-trical power is applied to the control circuit; the actuation of any of the release switches will release the load. When the CARGO REL switch is pressed and the release sole-noid begins to move, a switch closes, lighting theCARGO HOOK OPEN advisory light. The load arm will swing open, releasing the cargo. When the sling is detached from the load beam, spring tension on the arm will cause it to close and relatch, putting out theCARGO HOOK OPEN advisory light. The normal release system is a one-shot cycle; once the solenoid travel begins and the load arm relatches, the release cycle can again be initiated. Power to operate the normal release system is supplied from the No.

2 dc primary bus through circuit breakers markedCARGO HOOK CONTR andPWR.

4.17.3.2 Operational Check - Normal Release

Mode.

1. CARGO HOOK CONTR switch - As re-quired. CKPT for pilot and copilot check, or ALL for crewmember check.

2. CARGO HOOK ARMING switch -

ARMED .

3. HOOK ARMED advisory light - Check on.

4. Place about 20 pounds downward pressure on load beam.

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5. CARGO REL switch (pilot and copilot);

NORMAL RLSE (crewmember) - Press and release.

6. Load beam - Check open.CARGO HOOK OPEN advisory light - On.

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Change 10 4-42.1/(4-42.2 Blank)

SA

AA0367_1B

CONTR

CKPT

ARMING

SAFETEST NORM

CARGO HOOK

EMERG REL

O P E N

SHORT ALL ARMED

CARGO HOOK STOWAGE

CARGO HOOK CONTROL PANEL

COLLECTIVE STICK GRIP CYCLIC STICK GRIP

EMERGENCY

RELEASE

SWITCH

NORMAL

RELEASE

SWITCH

A B C

C

B

A

D

E

ASSEMBLY

LEVER

BUMPER

CARGO HOOK

ACCESS DOOR

CARGO LOAD

BEAM

CABIN

FLOOR

FRONT

D

CARGO

REL.

HOOK

EMER REL

LATCH

Figure 4-23. Cargo Hook System (Sheet 1 of 2)

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7. CARGO HOOK OPEN advisory light - Check off when hook closes.

8. Repeat steps 4. through 7. for copilot and crew-member position.

4.17.3.3 Manual Release. Manual release of external

cargo can be done from the cabin, through a covered port in the floor, or by ground personnel from outside the helicop-ter, with power on or off. Turning the release control on the right side of the hook (Figure 4-23) clockwise, causes the latching mechanism to release the load beam. The load beam will not move unless a downward pressure is exerted to cause opening. With power applied to the helicopter and the CARGO HOOK ARMING switch at ARMED , the CARGO HOOK OPEN advisory light will go on at the start of release control turning, and will go off at the end of release control rotation.

4.17.3.4 Operational Check - Manual Release

Mode.

1. Manual release lever spring - Installed. Check that spring is straight and provides positive pressure on the lever.

2. Place about 20 pounds downward pressure on load beam.

3. Manual release lever - Pull up/turn fully clock-wise and release.

4. Load beam - Check open.

5. CARGO HOOK OPEN advisory light - On.

6. When downward pressure is released, load beam will close and latch.

7. CARGO HOOK OPEN advisory light - Off when hook closes.

4.17.4 Emergency Release Circuit Tester. The

cargo hook emergency release circuit tester (Figure2-7) markedCARGO HOOK EMERG REL on the upper con-sole, contains a test light and switch. The test light, marked TEST, goes on during circuit testing to indicate the system is functioning properly. The switch, with marked positions NORM , OPEN, and SHORT, is normally at NORM .

When the switch is placed toOPEN or SHORT and the cargoHOOK EMER REL switch on the pilot’s or copi-lot’s collective, orEMER RLSE switch on the crewmem-ber’s cargo hook control pendant is pressed, the circuit tester light will go on if the circuit is good.

4.17.4.1 Cargo Hook Emergency Release Circuit

Check.

1. EMERG REL TEST light - Press. Light should be on.

NOTE

To prevent unintentional discharge of the cargo hook explosive cartridge, the pilot shall call off each procedural step of the emergency release circuit test before that step is done. Station being checked shall re-ply to pilot’s command.

2. Pilot’s release - Check.

a. Short test.

(1) CARGO HOOK EMERG REL

switch - SHORT.

(2) Pilot’s HOOK EMER REL button - Press and hold.

(3) CARGO HOOK TEST light - On.

MANUAL

RELEASE

LEVER

COVER

(EXPLOSIVE CARTRIDGE

UNDER COVER)

LOAD BEAM

KEEPER

FRONT

CARGO HOOK

OPEN

STA

343.0STA

363.0

SA

AA0367_2A

E

Figure 4-23. Cargo Hook System (Sheet 2 of 2)

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(4) HOOK EMER REL button - Release.

TEST light off.

(5) Repeat steps (2) through (4) for copi-lot’s HOOK EMER REL button, and crewmember’s cargo hook control pendantEMER RLSE button.

b. Open test.

(1) CARGO HOOK EMERG REL

switch - OPEN.

(2) Pilot’s HOOK EMER REL button - Press and hold.

(3) CARGO HOOK TEST light - On.

(4) HOOK EMER REL button - Release.

TEST light off.

(5) Repeat steps (2) through (4) for copi-lot’s HOOK EMER REL button, and crewmember’s cargo hook control pendantEMER RLSE button.

3. CARGO HOOK EMERG REL switch - NORM . If the cargo hook is not to be used immediately after completing the circuit test check, theEMERG REL switch shall remain at OPEN until ready for load pickup.

4.17.4.2 Emergency Release.

NOTE

When the emergency hook release has been used and a replacement squib (explosive car-tridge) is not available, the hook can not be used until the explosive device is replaced, since the hook load beam will not close and lock.

Emergency release of an external cargo load is done by an electrically-fired explosive cartridge, initiated from ei-ther of the collective stick grip switches, markedHOOK EMER REL , or the crewman’s cargo hook control pen-dant, markedEMER RLSE . The emergency release is used when the electrical and manual releases are inoperative, and the load must be jettisoned. With theCARGO HOOK EMERG REL switch atNORM , power will be applied to the emergency release switch. Pressing the switch applies 28 vdc to the explosive cartridge, producing a high gas pressure to drive a piston in the lock assembly, releasing the load arm lock. The weight of the load will cause the

EM

ER

RLS

E

CARGO

HOOK

RL SENORMAL

SA

AA0368

A

STRAP

NORMAL

RELEASE

SWITCH

GUARD

EMER

RLSE

SWITCH

EMERGENCY

RELEASE SWITCH

GUARD

CARGO HOOK

NORMAL RLSE

SWITCH

CREWMEMBER’S CARGO HOOK

CONTROL PENDANT

PILOT SEAT

CARGO HOOK

A

CREWMEMBER’S CARGO

HOOK PENDANT STOWAGE

RIGHT SIDE

STA

343.0

STA

363.0

Figure 4-24. Crewmember’s Cargo Hook Control Pendant UH

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4-45 load arm to open. Once the emergency release is used, the hook will remain open and theCARGO HOOK OPEN advisory light will remain on until the explosive cartridge device is replaced. When the explosive cartridge device is replaced the load arm will close, the light will go off, and the emergency release mode is returned to operation. Power to operate the emergency release system is from the dc essential bus through a circuit breaker, markedCARGO

HOOK EMER .

4.17.5 Preflight. When cargo hook loads are to be car-

ried, checks within this paragraph and procedures of para-graphs 4.17.6, 4.17.7, 4.17.8 and 4.17.9 apply.

1. Cargo hook - Check condition, security and ex-plosive cartridge installed.

2. Emergency release system - Check. (Go to paragraph 4.17.4.)

3. Manual release - Check. (Go to paragraph 4.17.3.3.)

4.17.6 Before Takeoff.

1. CARGO HOOK EMERG REL switch -

NORM .

2. CARGO HOOK ARMING switch -

ARMED .

4.17.7 Emergency Release Procedure.

Pilot or copilotHOOK EMER REL or crew-man’s control pendantEMER RLSE - Press.

4.17.8 In-flight Procedures.

CAUTION

Cargo suspended from the cargo hook should not be over a 30° cone angle. To prevent damage to the cargo hook keeper, the pilot shall use extreme care to prevent placing load pressure on the keeper.

CARGO HOOK ARMING switch - As required.

ARMED for low altitude/low airspeed.SAFE at cruise al-titude and airspeed.

4.17.9 Before Landing.

CARGO HOOK ARMING switch -

ARMED .

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