Maintenance Test of the APU FDU not possible

TASK 26-13-00-810-812-A
Maintenance Test of the APU FDU not possible

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 26-13-00-710-002	BITE Test of the APU Fire and Overheat Detection System
ASM 261301
AMM 26-13-34-000-001	Removal of the APU Fire-Detection Unit (FDU)
AMM 26-13-34-400-001	Installation of the APU Fire-Detection Unit (FDU)
AMM 31-32-34-000-001	Removal of the CFDIU
AMM 31-32-34-400-001	Installation of the CFDIU

3. Fault Confirmation
Subtask 26-13-00-710-072-A

A. Do the BITE test of the APU fire and overheat detection system AMM 26-13-00-710-002.

4. Fault Isolation
Subtask 26-13-00-810-074-A

A. Remove the APU FDU (13WG):

make sure that there is no ground signal at the pin B/R of the APU FDU (13WG) on the wiring side ASM 261301.

(1) If there is no ground signal:

(2) If there is a ground signal:

remove the CFDIU (1TW)
make sure that there is no ground signal at the pin AA/8K of the CFDIU (1TW) on the wiring side ASM 261301.

(a) If there is no ground signal:

(b) If there is a ground signal:

do a check and repair the wiring between the CFDIU (1TW) pin AA/8K and the engine APU FDU (13WG) pin B/R ASM 261301
install the CFDIU (1TW)
install the APU FDU (13WG).

Subtask 26-13-00-710-073-A

B. Do the test given in Para. 3.

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