Left Hand LVDT Signal Failure on Channel B

TASK 78-31-00-810-966-A
Left Hand LVDT Signal Failure on Channel B

1. Possible Causes

HARNESS - LEFT TRAS [4131KS]
HARNESS - PYLON T/R [4130KS]
EEC WIRING HARNESS WF07 [4093KS]
LEFT UPPER ACTUATOR [3043KM2]
[4000KS]

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	PLIERS - JAWED, SOFT

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 71-00-00-810-843-A	Nacelle Component and Harness Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
AMM 71-13-00-410-802	Closing of the Fan Cowl Doors
AWM 715136
AWM 715179
AMM 73-21-01-000-801	Removal of the Electronic Engine Control (EEC)
AMM 73-21-01-400-801	Installation of the Electronic Engine Control (EEC)
AMM 73-21-67-000-801	Removal of the Electronic Engine Control (EEC) Wiring Harness (WF07)
AMM 73-21-67-400-801	Installation of the Electronic Engine Control (EEC) Wiring Harness (WF07)
AMM 78-31-00-710-805	Operational Test of Thrust Reverser with MCDU
AMM 78-31-04-000-801	Removal of the TRAS Locking-Feedback Actuator
AMM 78-31-04-400-801	Installation of the TRAS Locking-Feedback Actuator
AMM 78-31-61-000-811	Removal of the Left TRAS Monitoring Harness
AMM 78-31-61-000-813	Removal of the Pylon TRAS Monitoring Harness
AMM 78-31-61-400-811	Installation of the Left TRAS Monitoring Harness
AMM 78-31-61-400-813	Installation of the Pylon TRAS Monitoring Harness
AMM 78-36-00-010-802	Opening of the Thrust Reverser Cowl-Doors

3. Fault Confirmation
Subtask 78-31-00-710-281-A ** ON A/C NOT FOR ALL

A. Do the operational test of the thrust reverser with the MCDU to confirm this fault AMM 78-31-00-710-805.
(1) If the maintenance message does not come back, troubleshoot as described in the nacelle component and harness troubleshooting procedure for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-843).
(a) Monitor the engine for reoccurring maintenance message.
(2) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.

4. Fault Isolation

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

CAUTION: MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.

Subtask 78-31-00-810-310-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Get access to left hand upper locking feedback actuator (3043KM1) and EEC (4000KS):
(a) Open the right thrust reverser cowl-door AMM 78-36-00-010-802.
(2) On actuator, check the correct engagement of connector (4003KS-A).
(a) Repair as necessary.
(b) Do the test given in Para. 3.
(3) If you find no damage or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect connector (4003KS-A) AWM 715179.
(a) Do a visual inspection of the connector for bent pins, contamination or corrosion or other signs of damage.
(b) If you find damage:
1 Replace HARNESS - LEFT TRAS [4131KS] AMM 78-31-61-000-811 and AMM 78-31-61-400-811.
(4) If you find no damage, disconnect connector (4053VC-A) AWM 715179.
(a) Do a visual inspection of the connectors for bent pins, contamination or corrosion or other signs of damage.
(b) Do a continuity check (less than 5 ohms) between the pins of connectors (4003KS-A) and (4053VC) as follows:

Pin 8 and pin 10
Pin 7 and pin 21
Pin 9 and pin 23
Pin 2 and pin 24.

(c) Do a check of each wire for wire-to-wire, short circuit and short to ground.
(d) If you find a fault:
1 Replace HARNESS - LEFT TRAS [4131KS] AMM 78-31-61-000-811 and AMM 78-31-61-400-811.
2 Reconnect all connectors.
3 Do the test given in Para. 3.
(5) If your find no damage, disconnect connector (494VC-A) AWM 715179.
(a) Do a visual inspection of the connector for bent pins, contamination or corrosion or other signs of damage.
(b) Do a continuity check (less than 5 ohms) between the pins of connectors (4053VC-A) and 494VC as follows:

Pin 10 and pin 22
Pin 21 and pin 41
Pin 23 and pin 9
Pin 24 and pin 24.

(c) Do a check of each wire for wire-to-wire, short circuit and short to ground.
(d) If you find damage:
1 Replace HARNESS - PYLON T/R [4130KS] AMM 78-31-61-000-813 and AMM 78-31-61-400-813.
2 Reconnect all connectors.
3 Do the test given in Para. 3.
(6) If you find no damage or if the fault continues, disconnect connector P8 from EEC (4000KS) AWM 715136.
(a) Do a visual inspection of the connectors for bent pins, contamination or corrosion or other signs of damage.
(b) Do a continuity check (less than 5 ohms) between the pins of connectors P8 (4000KS-P8) and (494VC-A) as follows:

Pin i and pin 22
Pin H and pin 41
Pin J and pin 9
Pin K and pin 24.

(c) Do a check of each wire for wire-to-wire, short circuit and short to ground.
(d) If you find a fault:
1 Replace EEC WIRING HARNESS WF07 [4093KS] AMM 73-21-67-000-801 and AMM 73-21-67-400-801.
2 Reconnect all connectors.
3 Do the test given in Para. 3.
(7) If you find no damage on wirings or if the fault continues, check LVDT:
(a) Disconnect connector (4003KS-A).
(b) Do a visual inspection of the actuator (4003KS) for bent pins, contamination or corrosion or other signs of damage.
(c) At LVDT thrust reverser upper right actuator (4003KS), make sure that the resistance is in the range 230 - 310 ohms between pins 8 and 7.
(d) At LVDT thrust reverser upper right actuator (4003KS), make sure that the resistance is in the range 146 - 186 ohms between pins 9 and 7.
(e) At LVDT thrust reverser upper right actuator (4003KS), make sure that the resistance is in the range 160 - 200 ohms between pins 2 and 7.
(f) If you find a fault:
1 Replace LEFT UPPER ACTUATOR [3043KM2] AMM 78-31-04-000-801 and AMM 78-31-04-400-801.
(g) Do the test given in Para. 3.
(8) If the fault continues:
(a) Replace [4000KS] AMM 73-21-01-000-801 and AMM 73-21-01-400-801.

5. Close-up
Subtask 78-31-00-860-075-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the fan cowl door AMM 71-13-00-410-802.

[Rev.8 from Aug 2018] 2026.04.04 04:38:16 UTC