Failure of the Crossaisle Lights (Floor Proximity Emergency Escape Path Marking System) controlled by EPSU 12WL

TASK 33-51-00-810-844-A
Failure of the Crossaisle Lights (Floor Proximity Emergency Escape Path Marking System) controlled by EPSU 12WL

1. Possible Causes

EXIT MARKER [90WL4]
wiring
EXIT MARKER [90WL6]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 33-51-00-710-001	Operational Test of the Emergency Lights
AMM 33-51-00-710-007	Operational Test of the Emergency Lighting in the Cabin with the 'LIGHT EMER' Pushbutton Switch
ASM 335104
AMM 33-51-13-000-001	Removal of the Cabin Wall-Mounted Emergency-Exit-Markers
AMM 33-51-13-400-001	Installation of the Cabin Wall-Mounted Emergency-Exit-Markers

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 33-51-00-710-133-A ** ON A/C NOT FOR ALL

A. Do the operational test of the emergency lights with the MCDU AMM 33-51-00-710-001.

4. Fault Isolation
Subtask 33-51-00-810-142-A ** ON A/C NOT FOR ALL

A. If the test gives a different maintenance message, do the trouble shooting procedure related to the maintenance message.

Subtask 33-51-00-810-143-B ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) FPEEPMS CROSSAISLE LT/EPSU(12WL)EMER R:

replace the EXIT MARKER [90WL4] AMM 33-51-13-000-001 and AMM 33-51-13-400-001 if not illuminated.

(a) If the fault continues:

do a check and repair the wiring between:
lamp module 90WL4 pin 3 and EPSU 12WL pin -H.
lamp module 90WL4 pin 1 and GND ASM 335104.

Subtask 33-51-00-810-143-E ** ON A/C NOT FOR ALL

B. If the operational test gives the maintenance message:
(1) FPEEPMS CROSSAISLE LT/EPSU(12WL)EMER R:

do the operational test of the emergency lighting in the cabin by pushbutton switch AMM 33-51-00-710-007.
during the test monitor the EXIT MARKER [90WL4] and the EXIT MARKER [90WL6] ASM 335104.
replace the EXIT MARKER [90WL4] AMM 33-51-13-000-001 and AMM 33-51-13-400-001 if not illuminated.
replace the EXIT MARKER [90WL6] AMM 33-51-13-000-001 and AMM 33-51-13-400-001 if not illuminated ASM 335104.

(a) If the fault continues and:
1 The EXIT MARKER [90WL4] is not illuminated:

do a check and repair the wiring between:
lamp module 90WL4 pin 3 and EPSU 12WL pin -H.
lamp module 90WL4 pin 1 and GND ASM 335104.

2 The EXIT MARKER [90WL6] is not illuminated:

do a check and repair the wiring between:
lamp module 90WL6 pin 3 and EPSU 12WL pin -H.
lamp module 90WL6 pin 1 and GND ASM 335104.

Subtask 33-51-00-710-134-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

5. Close-up
Subtask 33-51-00-860-100-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:32:10 UTC