DOC AIRBUS | TSM A320FLeft Tertiary Lock Position Failed Unlocked
TASK 78-31-00-810-974-A
Left Tertiary Lock Position Failed Unlocked
1. Possible Causes
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 78-31-00-710-289-A ** ON A/C NOT FOR ALL
Subtask 78-31-00-860-084-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:38:17 UTC
Left Tertiary Lock Position Failed Unlocked
1. Possible Causes
- TERTIARY LOCK UNIT-TRAS, L [3021KM]
- HARNESS - LEFT TRAS [4131KS]
- HARNESS - PYLON T/R [4130KS]
- PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN A [4038KS]
- PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN B [4046KS]
[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 71-13-00-410-802 | Closing of the Fan Cowl Doors |
| AWM 715178 | |
| 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 78-30-00-440-805 | Reactivation of the Thrust Reverser System after Ground Maintenance |
| 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 78-31-20-000-801 | 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 |
| AMM 78-36-00-010-802 | Opening of the Thrust Reverser Cowl-Doors |
| AMM 78-37-00-710-801 | Operational Check of the Thrust Reverser Actuation System (TRAS) Track Lock |
| AMM 78-37-01-000-801 | Removal of the Thrust Reverser Actuator System (TRAS) Track Lock |
| AMM 78-37-01-400-801 | Installation of the Thrust Reverser Actuator System (TRAS) Track Lock |
Subtask 78-31-00-710-289-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 78-31-00-810-318-A ** ON A/C NOT FOR ALL A. If there is confirmation of the fault:
(1) Make sure the thrust reverser system is not inhibited AMM 78-30-00-440-805.
(2) Get access to left hand track lock and EEC (4000KS):
(a) Open the left thrust reverser cowl door AMM 78-36-00-010-802.
(b) Remove the track lock cover AMM 78-37-01-000-801.
(3) On track lock, at proximity sensors (4038KS) and (4046KS), 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 TERTIARY LOCK UNIT-TRAS, L [3021KM] AMM 78-37-01-000-801 and AMM 78-37-01-400-801.
2 Do the test given in Para. 3.
(4) If you find no damage or if the fault continues, do an operational test of the thrust reverser actuation system track lock AMM 78-37-00-710-801.
(a) If the track lock is faulty:
1 Replace TERTIARY LOCK UNIT-TRAS, L [3021KM] AMM 78-37-01-000-801 and AMM 78-37-01-400-801.
2 Do the test given in Para. 3.
(5) If you find no damage or if the fault continues, make sure that no fault messages for the track lock valve failed open comes on.
(a) If any fault message comes on, troubleshoot it.
(6) If you find no damage or if the fault continues, check the correct engagement of connectors (4038KS-A) and (4046KS-A).
(a) Correct as necessary.
(b) Do the test given in Para. 3.
(7) If you find no fault or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect connectors (4038KS-A) and (4046KS-A) and do a visual inspection of the connectors for bent pins, contamination or corrosion or other signs of damage.
(a) If you find damage:
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.
(8) If you find no damage, disconnect connectors (4052VC-A) and (4053VC-A) AWM 715178 and 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 (4038KS-A) and (4052VC) as follows:
(e) 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.
(9) If you find no damage, disconnect connectors (491VC-A) and (494VC-A) AWM 715178 and 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 (4052VC-A) and (491VC) as follows:
(e) 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.
(10) If you find no damage on wirings or if the fault continues, replace the proximity sensors:
(a) Replace PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN A [4038KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801 and,
(b) Replace PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN B [4046KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801.
(c) Do the test given in Para. 3.
(11) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
5. Close-up(1) Make sure the thrust reverser system is not inhibited AMM 78-30-00-440-805.
(2) Get access to left hand track lock and EEC (4000KS):
(a) Open the left thrust reverser cowl door AMM 78-36-00-010-802.
(b) Remove the track lock cover AMM 78-37-01-000-801.
(3) On track lock, at proximity sensors (4038KS) and (4046KS), 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 TERTIARY LOCK UNIT-TRAS, L [3021KM] AMM 78-37-01-000-801 and AMM 78-37-01-400-801.
2 Do the test given in Para. 3.
(4) If you find no damage or if the fault continues, do an operational test of the thrust reverser actuation system track lock AMM 78-37-00-710-801.
(a) If the track lock is faulty:
1 Replace TERTIARY LOCK UNIT-TRAS, L [3021KM] AMM 78-37-01-000-801 and AMM 78-37-01-400-801.
2 Do the test given in Para. 3.
(5) If you find no damage or if the fault continues, make sure that no fault messages for the track lock valve failed open comes on.
(a) If any fault message comes on, troubleshoot it.
(6) If you find no damage or if the fault continues, check the correct engagement of connectors (4038KS-A) and (4046KS-A).
(a) Correct as necessary.
(b) Do the test given in Para. 3.
(7) If you find no fault or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect connectors (4038KS-A) and (4046KS-A) and do a visual inspection of the connectors for bent pins, contamination or corrosion or other signs of damage.
(a) If you find damage:
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.
(8) If you find no damage, disconnect connectors (4052VC-A) and (4053VC-A) AWM 715178 and 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 (4038KS-A) and (4052VC) as follows:
- Pin 2 and pin 8
- Pin 5 and pin 19
- Pin 3 and pin 20.
- Pin 2 and pin 8
- Pin 5 and pin 19
- Pin 3 and pin 20.
(e) 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.
(9) If you find no damage, disconnect connectors (491VC-A) and (494VC-A) AWM 715178 and 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 (4052VC-A) and (491VC) as follows:
- Pin 8 and pin 10
- Pin 19 and pin 25
- Pin 20 and pin 26.
- Pin 8 and pin 10
- Pin 19 and pin 25
- Pin 20 and pin 26.
(e) 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.
(10) If you find no damage on wirings or if the fault continues, replace the proximity sensors:
(a) Replace PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN A [4038KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801 and,
(b) Replace PROX SENSOR-L T/R LOWER TERTIARY LOCK, CHAN B [4046KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801.
(c) Do the test given in Para. 3.
(11) If the fault continues:
(a) Replace
(b) Do the test given in Para. 3.
Subtask 78-31-00-860-084-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.