TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
6. Door fails to lower when either switch held to close (cont.)  Defective landing gear safety circuit Defective control switch Defective control valve Defective wiring Faulty control valve Defective wiring  (b) No ground at pin 3 (c) No voltage at pin 1--check for continuity across terminals 1C-1NO of control switch No. 1 and No. 2 and pins B and D of control valve. IF -1) No continuity across switch terminals 2) No continuity across control valve pins B and D 3) Continuity OK B. Indicator not at position 2--check for 28v dc at pin B and continuity to ground at pin E of connector D1220 of control valve. IF (1) Voltage and ground OK (2) No continuity to ground  Refer to landing gear module or 338 trouble shooting (32-09-100) Repair or replace control switch Replace control valve Repair wiring between pin 1 of shutoff valve and pin D of control valve Replace control valve Repair circuit between pin E and ground 

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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
6. Door fails to lower when either switch held to close (cont)  Defective wiring  Defective canopy position or control switch  (3) No voltage at pin B -- check for continuity across terminals 1 and 2 of each hatrack interlock switches and door locked switch. If door is below canopy position, check for continuity across terminals 2C-2NO of control switch No. 1 and terminals 1 and 3 of canopy position A switch. If door is above canopy position, check for continuity across terminals 2C-2NC and 4C-4NC of control switch No. 1, 2C-2NO and 4C-4NC of control switch No. 2, and terminals 1 and 3 of canopy position A of switch. IF --(a) Continuity OK (b) No continuity  Repair wiring between circuit breaker and shut-off valve pin B Adjust or replace defective switch 

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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
7. Door does not stop at canopy position when lowered from full open position 8. Door unlocked light is not extinguished when door is closed and locked  Defective canopy position A. switch Defective door actuator (no ram lock) Door locked switch out of adjustment Defective door locked switch  A. B. A. (1) (2) (a)  Check for short across terminals 1 and 3 of canopy position A switch IF -Short exists No short exists Check door warning light on warning module is illuminated. IF -Warning light is illuminate--unlock door and depress plunger on door locked switch. IF - Unlocked and warning lights are extinguished Either unlocked or warning light, or both remains illuminated; check for continuity across terminals 10 and 11 or 7 and 8 of door locked switch. IF Continuity OK  Adjust or replace canopy position A switch Replace door actuator Adjust door locked switch Repair or replace door locked switch 

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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
8. Door unlocked light is not extinguished when door is closed and locked (cont.)  Main cargo door position switch out of adjustment Defective door position switch Defective lock mechanism Defective light socket Defective wiring  (b) No continuity -Disconnect wires from terminal 10 of terminal strip T259 (located behind the ceiling panel inboard of the aft section of the cargo door hinge line) and open main cargo door until door position switch plunger is accessible. Depress plunger on door position switch to simulate door closed condition. IF 1) Cargo door unlocked and warning lights are extinguished 2) Cargo door unlocked or warning light, or both remains illuminated -check for continuity across terminals 3 and 12 or 1 and 5 of door position switch. IF -a) Continuity OK-b) No continuity B. Warning light is not illuminated--check for short across terminals 1 and 3 of unlocked light socket. IF - (1) Short exists (2) No short exists  Adjust door position switch Repair or replace door position switch Repair or replace lock mechanism Replace light socket Repair wiring between light socket and door locked or door position switch 

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MAIN CARGO DOOR SYSTEM – SERVICING
1. General
A.  This procedure provides instructions for bleeding, filling and leak-checking the main cargo door hydraulic system and should be used any time a main cargo door hydraulic component has been replaced or reinstalled. Tubing, hydraulic components and actuators should be continually checked for leaks during procedure. Should any fluid spill on the airplane, decontaminate (Ref Chapter 12, Cleaning and Washing). Filling and bleeding of the A, B, and standby hydraulic systems should be completed before operating the main cargo door (Ref Chapter 29).
　
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