Loss of the columns 2 and 4 of the legend of the APU FIRE Pushbutton-Switch

TASK 26-13-00-810-809-A
Loss of the columns 2 and 4 of the legend of the APU FIRE Pushbutton-Switch

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 26-12-12-000-001	Removal of the ENG/APU Fire Panel
AMM 26-12-12-400-001	Installation of the ENG/APU Fire Panel
AMM 26-13-00-710-002	BITE Test of the APU Fire and Overheat Detection System
ASM 261301
ASM 331405
AMM 33-14-33-000-001	Removal of the Annunciator-Light Test and Interface-Board
AMM 33-14-33-400-001	Installation of the Annunciator-Light Test and Interface-Board

3. Fault Confirmation
Subtask 26-13-00-710-066-A

A. Do the BITE test of the APU Fire and Overheat Detection System AMM 26-13-00-710-002.

4. Fault Isolation
Subtask 26-13-00-810-071-A

A. If the columns 2 and 4 of the legend of the APU FIRE pushbutton-switch do not come on during the test:

on overhead panel 25VU, set the ANN LT switch to TEST and do a check if the columns 2 and 4 of the legend of the APU FIRE pushbutton-switch come on.

(1) If the columns 2 and 4 of the legend come on:

replace the BOARD-ANN LT TEST & INTFC [2LP] AMM 33-14-33-000-001 and AMM 33-14-33-400-001.

(a) If the fault continues:

do a check and repair of the aircraft wiring from:
the BOARD-ANN LT TEST & INTFC (2LP) A/38 to the next terminal block;
the BOARD-ANN LT TEST & INTFC (2LP) A/39 to the next terminal block;
ASM 331405.

(2) If the columns 2 and 4 of the legend do not come on:

(a) If the fault continues:

do a check and repair of the aircraft wiring from:
the ENG/APU FIRE PNL (1WD) F/A to the next terminal block;
the ENG/APU FIRE PNL (1WD) F/B to the BOARD-ANN LT TEST & INTFC (2LP) A/37;
ASM 261301.

Subtask 26-13-00-710-067-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:17 UTC