EPSU - Battery Fault

TASK 33-51-00-810-802-A
EPSU - Battery Fault

1. Possible Causes

BATTERY
POWER-EMERGENCY SUPPLY [10WL]
EPSU [11WL]
EPSU [12WL]
EPSU [13WL]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 33-51-00-710-001	Operational Test of the Emergency Lights
AMM 33-51-00-710-006	Operational Test of Emergency Lights not with CIDS
AMM 33-51-38-000-001	Removal of the Emergency Power-Supply Unit (EPSU)
AMM 33-51-38-000-002	Removal of the Battery of the Emergency Power-Supply Unit
AMM 33-51-38-400-001	Installation of the Emergency Power-Supply Unit (EPSU)
AMM 33-51-38-400-002	Installation of the Battery of the Emergency Power-Supply Unit

3. Fault Confirmation

CAUTION: DO NOT USE THE TEACH-IN PROCEDURE AS AN ALTERNATIVE FOR TROUBLESHOOTING. A TEACH-IN PROCEDURE IS NOT A RESET PROCEDURE. BEFORE YOU DO A TEACH-IN PROCEDURE, MAKE SURE THAT YOU CORRECTED ALL FAILURES. IF YOU DO NOT OBEY THIS, FAILURES CAN CAUSE A MALFUNCTION OF THE CABIN EMERGENCY LIGHTING SYSTEM.

Subtask 33-51-00-710-052-A ** ON A/C NOT FOR ALL

A. Do the operational test of the emergency lighting system AMM 33-51-00-710-001.

4. Fault Isolation
Subtask 33-51-00-810-051-C ** ON A/C NOT FOR ALL

A. If the operational test gives the maintenance message:
(1) EPSU BATTERY FWD L:

do the operational test of the battery of the POWER SUPPLY UNIT-EMERGENCY (10WL) AMM 33-51-00-710-006.

(a) If the red BATT FAULT LED comes on:

Replace the BATTERY AMM 33-51-38-000-002 and AMM 33-51-38-400-002,
do the operational test of the battery again.

1 If the fault continues:

replace the POWER-EMERGENCY SUPPLY [10WL] AMM 33-51-38-000-001 and AMM 33-51-38-400-001.

(2) EPSU BATTERY EMER L:

do the operational test of the battery of the POWER SUPPLY UNIT-EMERGENCY (11WL) AMM 33-51-00-710-006.

(a) If the red BATT FAULT LED comes on:

Replace the BATTERY AMM 33-51-38-000-002 and AMM 33-51-38-400-002,
do the operational test of the battery again.

1 If the fault continues:

replace the EPSU [11WL] AMM 33-51-38-000-001 and AMM 33-51-38-400-001.

(3) EPSU BATTERY EMER R:

do the operational test of the battery of the POWER SUPPLY UNIT-EMERGENCY (12WL) AMM 33-51-00-710-006.

(a) If the red BATT FAULT LED comes on:

Replace the BATTERY AMM 33-51-38-000-002 and AMM 33-51-38-400-002,
do the operational test of the battery again.

1 If the fault continues:

replace the EPSU [12WL] AMM 33-51-38-000-001 and AMM 33-51-38-400-001.

(4) EPSU BATTERY AFT L:

do the operational test of the battery of the POWER SUPPLY UNIT-EMERGENCY (13WL) AMM 33-51-00-710-006.

(a) If the red BATT FAULT LED comes on:

Replace the BATTERY AMM 33-51-38-000-002 and AMM 33-51-38-400-002,
do the operational test of the battery again.

1 If the fault continues:

replace the EPSU [13WL] AMM 33-51-38-000-001 and AMM 33-51-38-400-001.

Subtask 33-51-00-710-053-A ** ON A/C NOT FOR ALL

B. Do the test as given in the Para. 3.A.

5. Close-up
Subtask 33-51-00-860-065-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:06 UTC