Maintenance Test of the FDU 1 Not Possible

TASK 26-12-00-810-840-A
Maintenance Test of the FDU 1 Not Possible

1. Possible Causes

FDU-ENG1 [2WD1]
CFDIU [1TW]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 26-12-00-710-002	Operational Test of the Engine Fire and Overheat Detection with the Centralized Fault Display System (CFDS)
ASM 261202
AMM 26-12-34-000-001	Removal of the Engine Fire-Detection Unit (FDU)
AMM 26-12-34-400-001	Installation of the Engine 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 26-12-00-740-050-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the operational test of the engine fire and overheat detection from the Multipurpose Control and Display Unit (MCDU) AMM 26-12-00-710-002.
(a) If you cannot do the test:

go to Para. 4.A.

(b) If you can do the test:

no maintenance action is necessary.

4. Fault Isolation
Subtask 26-12-00-810-093-A ** ON A/C NOT FOR ALL

A. Remove the engine 1 FDU (2WD1):

make sure that there is no ground signal at the pin B/R of the engine 1 FDU (2WD1) on the wiring side ASM 261202.

(1) If there is no ground signal:

replace the FDU-ENG1 [2WD1] AMM 26-12-34-000-001 and AMM 26-12-34-400-001.

(2) If there is a ground signal:

remove the CFDIU (1TW)
make sure that there is no ground signal at the pin AA/12F of the CFDIU (1TW) on the wiring side ASM 261202.

(a) If there is no ground signal:

replace the CFDIU [1TW] AMM 31-32-34-000-001 and AMM 31-32-34-400-001
install the engine 1 FDU (2WD1).

(b) If there is a ground signal:

do a check and repair the wiring between the CFDIU (1TW) pin AA/12F and the engine 1 FDU (2WD1) pin B/R ASM 261202
install the CFDIU (1TW)
install the engine 1 FDU (2WD1).

Subtask 26-12-00-740-051-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:11 UTC