AFT ENTRY DOOR AND AIRSTAIR - TROUBLE SHOOTING
EFFECTIVITY
Airplanes with Aft Airstair
1. General
A. This trouble shooting of the aft entry door and airstair will cover the electrical functions of the system. Should a mechanical malfunction occur caused by misalignment of the pushrods, bellcranks and attaching hardware, refer to Aft Entry and Airstair - Adjustment/Test and 52-14-101, Aft Airstair Folding Mechanism - Adjustment/Test.
B. Prior to initiating the following trouble shooting procedures, carefully examine the accessible mechanical components for proper installation. Correct all noted discrepancies before proceeding.
C. Isolation of an electrical malfunction is accomplished using electrical connectors D4846J and D4846P on the aft airstairs control panel. Voltage and continuity checks completed through the connectors determine the position of switches, electrical continuity, and system operation.
D. Ensure that the aft airstair actuator and lights and control circuit breakers are closed on load control center P6, and that electrical power is available for system operation. The console control handle must be in the DOOR UNLATCHED position before attempting operation of the airstair.
NOTE: Place the tread lights switch to the ON position to determine the presence of dc power.
Aug 15/71 52-14-0 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
2.
Extend Aft Entry Door and Airstair Trouble Shooting Chart
3.
Retract Aft Entry Door and Airstair Trouble Shooting Chart
TROUBLE PROBABLE CAUSE ISOLATION PROCEDURE REMEDY
Airstair fails to extend when control switch on internal or external control panel is operated 1. Faulty internal control 2. Faulty external control switch 3. Faulty door arming switch 4. Faulty extend limit switch 1. Attempt operation of airstair from external control switch. If air stair extends, internal control switch is faulty. If airstair fails to extend, proceed to step 3. 2. Attempt operation of airstair from internal control switch. If air stair extends, external control switch is faulty. If airstair fails to extend, proceed to step 3. 3. Disconnect electrical connector D4846P from mating connector D4846J on aft airstair control panel. Check for 28 volts dc on D4846J between pin No. 8 and ground. If voltage is not available, door arming switch is faulty. If voltage is available, proceed to step 4. 4. Check for continuity on connector D4846P between pin No. 2 and ground. If continuity is not present, extend limit switch is faulty. If continuity is present, proceed to step 5. 1. Replace faulty internal control switch 2. Replace faulty external control switch 3. Adjust or replace door arming switch. (Refer to 52-14-11) 4. Adjust or replace extend limit switch. (Refer to 52-14-81)
500
52-14-0 Feb 15/68
Page 102
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
TROUBLE PROBABLE CAUSE ISOLATION PROCEDURE REMEDY
Airstair fails to extend when control switch on internal or external control panel is operated (cont.) 5. Faulty extend or retract relay 6. Faulty extend relay or ac power unit 5. Check for continuity on connector D4846J between pin No. 2 and pin No.7. If continuity is not present, replace retract relay. If continuity is present, reconnect D4846P to D4846J and proceed to step 6. 6. Disconnect connector D502 from ac power unit. Attempt operation of system with control switch and check for 115 volts ac between pins No. 1, 2, 3, and ground on pin No. 4. If voltage is not available, extend relay is faulty. If voltage is available, ac power unit is faulty 5. Replace extend relay and/or retract relay6. Replace extend relay or ac power unit
500
Feb 15/68 52-14-0
Page 103
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
TROUBLE PROBABLE CAUSE ISOLATION PROCEDURE REMEDY
Airstair fails to retract when control switch on internal or external control panel is operated 1. Faulty internal control switch 2. Faulty external control switch 3. Faulty door arming switch 4. Faulty retracting limit switch 1. Attempt operation of airstair from external control switch. If airstair retracts, internal control switch is faulty. If airstair fails to retract, proceed to step 3. 2. Attempt operation of airstair from internal control switch. If airstair retracts, external control switch is faulty. If airstair fails to retract, proceed to step 3. 3. Disconnect electrical connector D4846P from mating connector D4846J on airstair control panel. Check for 28 volts dc on D4846J between pin No. 8 and ground. If voltage is not available, door-arming switch is faulty. If voltage is available, proceed to step 4. 4. Check for continuity on connector D4846F between pin No. 1 and ground. If continuity is not present, retract limit switch is faulty. If continuity is present, proceed to step 5. 1. Replace faulty internal control switch2. Replace faulty external control switch 3. Adjust or replace door-arming switch. (Refer to 52-14-11.)4. Adjust or replace retract limit switch. (Refer to, 52-14-81.)
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