WING ANTI-ICING SYSTEM - TROUBLE SHOOTING
EFFECTIVITY
Airplanes with Wing TAI System Ground Operation Capability
1.  General
A.  Before using the following trouble shooting chart prepare to test the wing TAI system in accordance with adjustment test procedure. Proceed with test to extent practical to determine extent of trouble. When checking system for air mode of operation press GRD SENSING TEST switch on landing gear module.
2.  Trouble Shooting Chart
Feb 20/84 30-11-01 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
One light does not illuminate on press to test or in any switch position Neither light illuminates on press to test or in valve transit One light does not agree with switch position  Defective lamp Defective lamp base Defective wiring Defective valve control circuit  Check continuity of lamp. IF -No Continuity -Continuity OK - Check for defective lamp base Check for continuity with lamp installed between base terminals 1 and 2, and 1 and 3 with light cover normal and between terminals 1 and 4 with light cover depressed. IF -No Continuity Continuity OK Remove receptacle D462 from P5-11 module and check for dc power at pin 31. IF -No Power Power OK - Check for continuity between pin 29 and ground. IF -No Continuity Continuity OK Check if valve position agrees with switch position. IF - Replace lamp Replace lamp base Replace P5-11 module Repair wiring between circuit breaker and receptacle Repair wiring between receptacle and ground Replace P5-11 module 

501 
30-11-01  Feb 20/84 
Page 102 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
One light does not agree with switch position (Cont)  Defective valve control circuit (Cont)  Valve agrees with switch position check for defective valve position indication circuit Valve does not agree with switch position-remove receptacle D648 from P5-11 module if left valve or D462 if right valve and check for ac power at pin 11. IF -No Power Power OK -Jumper pin 10 on receptacle D648 to pin 10 on P5-11 module if left valve or replace receptacle D462 if right valve and check for ac power at pins 3 and 5 of module receptacle D648 with switch in OFF position and at pins 4 and 6 with switch in ON position. IF -No Power Power OK - Install receptacle D648 on P5-11 module and remove receptacle to respective valve and check for power at pin 1 for switch in ON position. IF - Repair wiring between circuit breaker and pin 11 of receptacle Replace P5-11 module 

501 
Feb 20/84  30-11-01 
Page 103 
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TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
One light does not agree with switch position (Cont) Neither light agrees with switch position  Defective valve control circuit (Cont) Defective valve control circuit  No power Power OK - Check for continuity between pin 3 of valve receptacle and ground. IF -No continuity Continuity OK Disconnect receptacle D462 from P5-11 module dc power at pin 24. IF -No Power Power OK - Check for continuity between pin 21 and ground. IF -No Continuity Continuity - Disconnect receptacle from both ground overheat thermal switches and check for continuity between pins 1 and 2 on each switch. IF - Repair wiring between receptacle D648 and receptacle valve receptacle Repair wiring between valve receptacle and ground Replace valve Repair wiring between circuit breaker and receptacle (See Landing Gear Miscellaneous Electrical Components - Chapter 32, for operation of safety relay) Replace P5-11 module 

501 
30-11-01  Feb 20/84 
Page 104 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
Neither light agrees with switch position (Cont) Overheat protection does not close valves when air temperature exceeds 125°C  Defective valve control circuit (Cont) Defective overheat control circuit  ContinuityNo Continuity Disconnect receptacle D462 from P5-11 module and check for continuity to ground while heating either thermal switch to 125°C in accordance with system adjustment/test procedure. IF -Continuity OK No Continuity - Remove receptacle from thermal switch and check for continuity across pin 1 and 2 while conducting test. IF -Continuity OK No Continuity   Replace defective switch Repair wiring between module receptacle and thermal switch receptacle Replace P5-11 module Repair wiring between module receptacle and switch receptacle Replace thermal switch 
　
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