DOC AIRBUS | AMM A320FFunctional Check of the Electrical Tertiary Lock System (TLS) [CFML]
TASK 78-37-51-720-801-A
Functional Check of the Electrical Tertiary Lock System (TLS)
This task gives the instructions to do a functional check of the Electrical Tertiary Lock System (TLS). The functional check makes sure that the roller attached to the translating cowl (transcowl) correctly engages with the latch hook on the TLS. The thrust reverser cannot accidentally move to the deployed position when the TLS has locked the transcowl.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Work Zones and Access Panels
C. Referenced Information
3. Job Set-up
Subtask 78-37-51-941-075-A
Subtask 78-37-51-720-050-A
Subtask 78-37-51-410-075-A
[Rev.10 from 2021]
2026.04.01 03:37:27 UTC
Functional Check of the Electrical Tertiary Lock System (TLS)
WARNING:
BE CAREFUL WHEN YOU DO WORK ON THE ENGINE PARTS AFTER THE ENGINE SHUTDOWN. USE APPLICABLE THERMAL GLOVES. THE ENGINE PARTS CAN STAY HOT FOR ONE HOUR AFTER SHUTDOWN AND CAN BURN YOU.
1. Reason for the JobThis task gives the instructions to do a functional check of the Electrical Tertiary Lock System (TLS). The functional check makes sure that the roller attached to the translating cowl (transcowl) correctly engages with the latch hook on the TLS. The thrust reverser cannot accidentally move to the deployed position when the TLS has locked the transcowl.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | AR | WARNING NOTICE(S) |
| ZONE/ACCESS | ZONE DESCRIPTION |
|---|---|
| FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1) | |
| 437AL, 438AR, 452ER | |
| FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2) | |
| 447AL, 448AR, 462ER | |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 71-13-00-010-803-A | Opening of the Fan Cowl Doors |
| TASK 71-13-00-410-803-A | Closing of the Fan Cowl Doors |
| TASK 73-29-00-740-804-A | Thrust Reverser Cycling Test (Menu Mode) |
| TASK 78-30-00-040-807-A | Deactivation of the Thrust Reverser System for Nacelle Maintenance (ICU) |
| TASK 78-30-00-440-807-A | Reactivation of the Thrust Reverser System after Nacelle Maintenance (ICU) |
| TASK 78-31-41-040-802-A | Unlocking of the Thrust-Reverser Upper Actuators |
| TASK 78-31-41-440-802-A | Locking of the Thrust-Reverser Upper Actuators |
| TASK 78-32-50-010-801-A | Manually Deploy the Translating Cowl |
| TASK 78-32-50-410-801-A | Manually Stow the Translating Cowl |
| TASK 78-37-00-040-803-A | Deactivation of the Electrical Tertiary Lock System |
| TASK 78-37-00-440-803-A | Activation of the Electrical Tertiary Lock System |
Functional Check of the Electrical Tertiary LockSubtask 78-37-51-941-075-A
A. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put WARNING NOTICE(S) in position to tell persons not to operate:
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).
Subtask 78-37-51-010-097-A (1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put WARNING NOTICE(S) in position to tell persons not to operate:
- The ENG/MODE selector switch, and
- The ENG/MASTER 1(2) control switch.
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).
B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
Subtask 78-37-51-040-066-A (1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
C. Deactivation of the Thrust Reverser
Subtask 78-37-51-010-098-A WARNING:
YOU MUST DEACTIVATE THE THRUST REVERSER BEFORE YOU DO WORK ON OR AROUND IT. IF YOU DO NOT, THE THRUST REVERSER CAN OPERATE ACCIDENTALLY AND CAUSE AN INJURY AND/OR DAMAGE.
(1) Make sure that you did the deactivation of the thrust reverser for nacelle maintenance (Ref. AMM TASK 78-30-00-040-807). D. Get Access
(1) Make sure that the translating cowl is in the fully stowed position before you start this functional check.
(2) Open the aft 6 o'clock access door:
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
452ER
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
462ER
4. Procedure(1) Make sure that the translating cowl is in the fully stowed position before you start this functional check.
(2) Open the aft 6 o'clock access door:
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
452ER
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
462ER
Subtask 78-37-51-720-050-A
A. Functional Check of the Electrical Tertiary Lock System (TLS)
(1) Unlock the primary lock on the upper left actuator (Ref. AMM TASK 78-31-41-040-802).
(2) Unlock the primary lock on the upper right actuator (Ref. AMM TASK 78-31-41-040-802).
(3) Make sure that the electrical TLS is in the active position (Ref. AMM TASK 78-37-00-440-803).
(4) Manually deploy the translating cowl as follows:
(a) Obey the usual instructions to deploy the translating cowl (Ref. AMM TASK 78-32-50-010-801) but without deactivating the electrical TLS.
(b) The translating cowl can move on a small distance, but the electrical TLS must stop the movement of the translating cowl. You will hear a click from the Manual Drive Unit (MDU). The click tells you that the electrical TLS has correctly stopped the translating cowl movement, and the clutch in the MDU has slipped.
(5) Fully stow the translating cowl (Ref. AMM TASK 78-32-50-410-801).
(6) Deactivate the electrical TLS (Ref. AMM TASK 78-37-00-040-803).
(7) Manually deploy the translating cowl as follows:
(a) Manually deploy the translating cowl (Ref. AMM TASK 78-32-50-010-801).
(8) Activate the electrical TLS (Ref. AMM TASK 78-37-00-440-803).
(9) Manually stow the translating cowl (Ref. AMM TASK 78-32-50-410-801).
(10) Make sure that the primary lock on the upper left actuator is locked (Ref. AMM TASK 78-31-41-440-802).
(11) Make sure that the primary lock on the upper right actuator is locked (Ref. AMM TASK 78-31-41-440-802).
5. Close-up(1) Unlock the primary lock on the upper left actuator (Ref. AMM TASK 78-31-41-040-802).
(2) Unlock the primary lock on the upper right actuator (Ref. AMM TASK 78-31-41-040-802).
(3) Make sure that the electrical TLS is in the active position (Ref. AMM TASK 78-37-00-440-803).
(4) Manually deploy the translating cowl as follows:
(a) Obey the usual instructions to deploy the translating cowl (Ref. AMM TASK 78-32-50-010-801) but without deactivating the electrical TLS.
(b) The translating cowl can move on a small distance, but the electrical TLS must stop the movement of the translating cowl. You will hear a click from the Manual Drive Unit (MDU). The click tells you that the electrical TLS has correctly stopped the translating cowl movement, and the clutch in the MDU has slipped.
(5) Fully stow the translating cowl (Ref. AMM TASK 78-32-50-410-801).
(6) Deactivate the electrical TLS (Ref. AMM TASK 78-37-00-040-803).
(7) Manually deploy the translating cowl as follows:
(a) Manually deploy the translating cowl (Ref. AMM TASK 78-32-50-010-801).
NOTE: The translating cowl deploys correctly this time, it was the TLS that stopped the translating cowl during the first check (see Para. 4.A.(4)).
(b) Make sure that the translating cowl continues to move to the fully deployed position. This tells you that the TLS operates correctly and does not prevent movement of the translating cowl when in the UNLOCKED position. (8) Activate the electrical TLS (Ref. AMM TASK 78-37-00-440-803).
(9) Manually stow the translating cowl (Ref. AMM TASK 78-32-50-410-801).
(10) Make sure that the primary lock on the upper left actuator is locked (Ref. AMM TASK 78-31-41-440-802).
(11) Make sure that the primary lock on the upper right actuator is locked (Ref. AMM TASK 78-31-41-440-802).
Subtask 78-37-51-410-075-A
A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the aft 6 o'clock access door:
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
452ER
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
462ER
(3) Make the thrust reverser serviceable after maintenance (Ref. AMM TASK 78-30-00-440-807).
(4) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
(5) Remove the WARNING NOTICE(S).
Subtask 78-37-51-710-059-A (1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the aft 6 o'clock access door:
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
452ER
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
462ER
(3) Make the thrust reverser serviceable after maintenance (Ref. AMM TASK 78-30-00-440-807).
(4) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
(5) Remove the WARNING NOTICE(S).
B. Return-to-Service Testing
(1) Do an operational test of the thrust reverser cycling (Ref. AMM TASK 73-29-00-740-804).
(1) Do an operational test of the thrust reverser cycling (Ref. AMM TASK 73-29-00-740-804).