DOC AIRBUS | TSM A320FLeft Hand Upper Locking Feedback Actuator Proximity Switch Signal Failure on Channel A
TASK 78-31-00-810-949-A
Left Hand Upper Locking Feedback Actuator Proximity Switch Signal Failure on Channel A
1. Possible Causes
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 78-31-00-710-264-A ** ON A/C NOT FOR ALL
Subtask 78-31-00-860-058-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:38:13 UTC
Left Hand Upper Locking Feedback Actuator Proximity Switch Signal Failure on Channel A
1. Possible Causes
- LEFT UPPER ACTUATOR [3043KM2]
- HARNESS - LEFT TRAS [4131KS]
- HARNESS - PYLON T/R [4130KS]
- EEC WIRING HARNESS WF06 [4089KS]
- PROX SENSOR-L T/R UPPER PRIMARY LOCK, CHAN A [4032KS]
[4000KS]
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | PLIERS - JAWED, SOFT |
| REFERENCE | DESIGNATION |
|---|---|
| TSM TASK 71-00-00-810-843-A | Nacelle Component and Harness Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults |
| AMM 71-13-00-010-802 | Opening of the Fan Cowl Doors |
| AMM 71-13-00-410-802 | Closing of the Fan Cowl Doors |
| AWM 715135 | |
| AWM 715178 | |
| 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 73-21-66-000-802 | Removal of the Electronic Engine Control (EEC) Wiring Harness (WF06) |
| AMM 73-21-66-400-802 | Installation of the Electronic Engine Control (EEC) Wiring Harness (WF06) |
| AMM 78-31-00-210-802 | General Visual Inspection (GVI) of the Proximity Sensor Targets |
| 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 78-31-20-000-801 | Removal of the TRAS Actuator Proximity-Sensors |
| AMM 78-31-20-400-801 | Installation of the TRAS Actuator Proximity-Sensors |
| 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 |
Subtask 78-31-00-710-264-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(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.
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 78-31-00-810-293-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 and EEC (4000KS):
(a) Open the fan cowl-doors AMM 71-13-00-010-802.
(2) On actuator, at proximity sensor (4032KS), make sure that the target is not missing and do a visual inspection of the target for bend, breakage or damage AMM 78-31-00-210-802.
(a) If you find a bend, breakage or other damage, or if the target is missing:
1 Replace LEFT UPPER ACTUATOR [3043KM2] AMM 78-31-04-000-801 and AMM 78-31-04-400-801.
2 Do the test given in Para. 3.
(3) If you find no damage or if the fault continues:
(a) Check for the correct engagement of connector (4032KS-A).
1 Repair as necessary.
2 Do the test given in Para. 3.
(4) If the check is OK or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect conector (4032KS-A) and do a visual inspection of the connector for bent pins, contamination or corrosion or other signs of damage.
(a) If you find damage, replace HARNESS - LEFT TRAS [4131KS] AMM 78-31-61-000-811 and AMM 78-31-61-400-811
(b) Do the test given in Para. 3.
(5) If you find no damage or if the fault continues, disconnect connector (4052VC-A) AWM 715178.
(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 (4032KS-A) and (4052VC) as follows:
(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.
(6) If you find no damage, disconnect connector (491VC-A) AWM 715178.
(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 (4052VC-A) and (491VC) as follows:
(d) If you find a fault:
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.
(7) If your find no damage or if the fault continues, disconnect connector P7 from EEC (4000KS) AWM 715135.
(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 P7 (4000KS-P7) and (491VC-A) as follows:
(d) If you find a fault:
1 Replace EEC WIRING HARNESS WF06 [4089KS] AMM 73-21-66-000-802 and and AMM 73-21-66-400-802.
2 Reconnect all connectors.
3 Do the test given in Para. 3.
(8) If you find no damage on wirings or if the fault continues, replace the proximity sensor.
(a) Replace PROX SENSOR-L T/R UPPER PRIMARY LOCK, CHAN A [4032KS] AMM 78-31-20-000-801 AMM 78-31-20-400-801.
(b) Do the test given in Para. 3.
(9) If the fault continues:
(a) Replace
5. Close-up(1) Get access to left hand upper locking feedback actuator and EEC (4000KS):
(a) Open the fan cowl-doors AMM 71-13-00-010-802.
(2) On actuator, at proximity sensor (4032KS), make sure that the target is not missing and do a visual inspection of the target for bend, breakage or damage AMM 78-31-00-210-802.
(a) If you find a bend, breakage or other damage, or if the target is missing:
1 Replace LEFT UPPER ACTUATOR [3043KM2] AMM 78-31-04-000-801 and AMM 78-31-04-400-801.
2 Do the test given in Para. 3.
(3) If you find no damage or if the fault continues:
(a) Check for the correct engagement of connector (4032KS-A).
1 Repair as necessary.
2 Do the test given in Para. 3.
(4) If the check is OK or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect conector (4032KS-A) and do a visual inspection of the connector for bent pins, contamination or corrosion or other signs of damage.
(a) If you find damage, replace HARNESS - LEFT TRAS [4131KS] AMM 78-31-61-000-811 and AMM 78-31-61-400-811
(b) Do the test given in Para. 3.
(5) If you find no damage or if the fault continues, disconnect connector (4052VC-A) AWM 715178.
(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 (4032KS-A) and (4052VC) as follows:
- Pin 2 and pin 4
- Pin 5 and pin 13
- Pin 3 and pin 14.
(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.
(6) If you find no damage, disconnect connector (491VC-A) AWM 715178.
(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 (4052VC-A) and (491VC) as follows:
- Pin 4 and pin 7
- Pin 13 and pin 8
- Pin 14 and pin 21.
(d) If you find a fault:
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.
(7) If your find no damage or if the fault continues, disconnect connector P7 from EEC (4000KS) AWM 715135.
(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 P7 (4000KS-P7) and (491VC-A) as follows:
- Pin W and pin 7
- Pin V and pin 8
- Pin U and pin 21.
(d) If you find a fault:
1 Replace EEC WIRING HARNESS WF06 [4089KS] AMM 73-21-66-000-802 and and AMM 73-21-66-400-802.
2 Reconnect all connectors.
3 Do the test given in Para. 3.
(8) If you find no damage on wirings or if the fault continues, replace the proximity sensor.
(a) Replace PROX SENSOR-L T/R UPPER PRIMARY LOCK, CHAN A [4032KS] AMM 78-31-20-000-801 AMM 78-31-20-400-801.
(b) Do the test given in Para. 3.
(9) If the fault continues:
(a) Replace
Subtask 78-31-00-860-058-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 doors AMM 71-13-00-410-802.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the fan cowl doors AMM 71-13-00-410-802.