DOC AIRBUS | TSM A320FLeft Lower Primary Lock Position Failed Unlocked
TASK 78-31-00-810-980-A
Left Lower Primary Lock Position Failed Unlocked
1. Possible Causes
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 78-31-00-710-295-A ** ON A/C NOT FOR ALL
Subtask 78-31-00-860-090-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:38:18 UTC
Left Lower Primary Lock Position Failed Unlocked
1. Possible Causes
- L LOWER ACTUATOR [3041KM2]
- COWL-ENG 1 THRUST REVERSER, L [3400KM1]
- COWL-ENG 2 THRUST REVERSER, L [3400KM2]
- flex shaft
- HARNESS - LEFT TRAS [4131KS]
- HARNESS - PYLON T/R [4130KS]
- PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN A [4034KS]
- PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN B [4042KS]
[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 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 78-31-00-210-802 | General Visual Inspection (GVI) of the Proximity Sensor Targets |
| AMM 78-31-00-710-805 | Operational Test of Thrust Reverser with MCDU |
| AMM 78-31-03-000-801 | Removal of the TRAS Locking Actuator |
| AMM 78-31-03-400-801 | Installation of the TRAS Locking Actuator |
| AMM 78-31-04-400-801 | Installation of the TRAS Locking-Feedback Actuator |
| AMM 78-31-07-000-801 | Removal of the Flex Shaft |
| AMM 78-31-07-400-801 | Installation of the Flex Shaft |
| 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 78-32-00-210-810 | Detailed Inspection of Thrust Reverser, Primary Sliders and Tracks |
| AMM 78-32-00-860-802 | Manual Extension of the Thrust-Reverser Translating Sleeves |
| AMM 78-32-00-860-803 | Manual Retraction of the Thrust-Reverser Translating Sleeves |
| AMM 78-32-01-000-802 | Removal of the Left Thrust Reverser Half - Engine 1 |
| AMM 78-32-01-000-803 | Removal of the Left Thrust Reverser Half - Engine 2 |
| AMM 78-32-01-400-802 | Installation of the Left Thrust Reverser Half - Engine 1 |
| AMM 78-32-01-400-803 | Installation of the Left Thrust Reverser Half - Engine 2 |
Subtask 78-31-00-710-295-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 78-31-00-810-324-A ** ON A/C NOT FOR ALL A. If there is confirmation of the fault:
(1) Get access to left hand lower locking feedback actuator (3041KM2) and EEC (4000KS):
(a) Open the fan cowl doors AMM 71-13-00-010-802.
(2) On actuator, at proximity sensors (4034KS) and (4042KS), 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 L LOWER ACTUATOR [3041KM2] AMM 78-31-03-000-801 and AMM 78-31-03-400-801.
2 Do the test given in Para. 3.
(3) If you find no damage to the target or if the fault continues, check if the target is in unlocked position.
(4) If yes, check the actuator rod end is correctly attached to translating sleeve fitting.
(a) Correct attachment if necessary AMM 78-31-04-400-801.
(b) Do the test given in Para. 3.
(5) If attachment is correct or the fault continues, manually extend the translating sleeve AMM 78-32-00-860-802.
(a) Make sure that the left translating sleeve and actuator move smoothly.
(b) Inspect the primary sliders and tracks AMM 78-32-00-210-810.
1 If you find damage:
a For ENG 1: replace COWL-ENG 1 THRUST REVERSER, L [3400KM1] AMM 78-32-01-000-802 and AMM 78-32-01-400-802.
b For ENG 2: replace COWL-ENG 2 THRUST REVERSER, L [3400KM2] AMM 78-32-01-000-803 and AMM 78-32-01-400-803.
(c) Manually retract the translating sleeve AMM 78-32-00-860-803.
1 If movements of both actuators are not synchronized:
a Replace flex shaft AMM 78-31-07-000-801 and AMM 78-31-07-400-801.
(d) If you do not find any damage:
1 Replace L LOWER ACTUATOR [3041KM2] AMM 78-31-03-000-801 and AMM 78-31-03-400-801.
2 Do the test given in Para. 3.
(6) If the target is in locked position or if the fault continues:
(a) Check for the correct engagement of connectors (4034KS-A) and (4042KS-A).
1 Repair as necessary.
2 Do the test given in Para. 3.
(7) If check is OK or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect connectors (4034KS-A) and (4042KS-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:
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 (4034KS-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 proximity sensors.
(a) Replace PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN A [4034KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801, and
(b) Replace PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN B [4042KS] 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
1 Do the test given in Para. 3.
5. Close-up(1) Get access to left hand lower locking feedback actuator (3041KM2) and EEC (4000KS):
(a) Open the fan cowl doors AMM 71-13-00-010-802.
(2) On actuator, at proximity sensors (4034KS) and (4042KS), 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 L LOWER ACTUATOR [3041KM2] AMM 78-31-03-000-801 and AMM 78-31-03-400-801.
2 Do the test given in Para. 3.
(3) If you find no damage to the target or if the fault continues, check if the target is in unlocked position.
(4) If yes, check the actuator rod end is correctly attached to translating sleeve fitting.
(a) Correct attachment if necessary AMM 78-31-04-400-801.
(b) Do the test given in Para. 3.
(5) If attachment is correct or the fault continues, manually extend the translating sleeve AMM 78-32-00-860-802.
(a) Make sure that the left translating sleeve and actuator move smoothly.
(b) Inspect the primary sliders and tracks AMM 78-32-00-210-810.
1 If you find damage:
a For ENG 1: replace COWL-ENG 1 THRUST REVERSER, L [3400KM1] AMM 78-32-01-000-802 and AMM 78-32-01-400-802.
b For ENG 2: replace COWL-ENG 2 THRUST REVERSER, L [3400KM2] AMM 78-32-01-000-803 and AMM 78-32-01-400-803.
(c) Manually retract the translating sleeve AMM 78-32-00-860-803.
1 If movements of both actuators are not synchronized:
a Replace flex shaft AMM 78-31-07-000-801 and AMM 78-31-07-400-801.
(d) If you do not find any damage:
1 Replace L LOWER ACTUATOR [3041KM2] AMM 78-31-03-000-801 and AMM 78-31-03-400-801.
2 Do the test given in Para. 3.
(6) If the target is in locked position or if the fault continues:
(a) Check for the correct engagement of connectors (4034KS-A) and (4042KS-A).
1 Repair as necessary.
2 Do the test given in Para. 3.
(7) If check is OK or if the fault continues, use a PLIERS - JAWED, SOFT to disconnect connectors (4034KS-A) and (4042KS-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:
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 (4034KS-A) and (4052VC) as follows:
- Pin 2 and pin 6
- Pin 5 and pin 16
- Pin 3 and pin 17.
- Pin 2 and pin 6
- Pin 5 and pin 16
- Pin 3 and pin 17.
(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 6 and pin 3
- Pin 16 and pin 2
- Pin 17 and pin 11.
- Pin 6 and pin 3
- Pin 16 and pin 2
- Pin 17 and pin 11.
(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 proximity sensors.
(a) Replace PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN A [4034KS] AMM 78-31-20-000-801 and AMM 78-31-20-400-801, and
(b) Replace PROX SENSOR-L T/R LOWER PRIMARY LOCK, CHAN B [4042KS] 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
1 Do the test given in Para. 3.
Subtask 78-31-00-860-090-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.