FDIU Inoperative

TASK 31-33-00-810-802-A
FDIU Inoperative

1. Possible Causes

Circuit Breaker 8TU
wiring
FDIU [2TU]
AMU [1RN]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-51-34-000-001	Removal of the Audio Management Unit (AMU) (1RN)
AMM 23-51-34-400-001	Installation of the Audio Management Unit (AMU) (1RN)
AMM 31-33-00-710-006	Operational Check of DFDR via MCDU
ASM 313301
AMM 31-33-34-000-001	Removal of the Flight Data Interface Unit (FDIU)
AMM 31-33-34-400-001	Installation of the Flight Data Interface Unit (FDIU)
ASM 313400

3. Fault Confirmation
Subtask 31-33-00-710-051-A ** ON A/C NOT FOR ALL

A. Do the FDIU (2TU) fault monitoring test via the CFDS AMM 31-33-00-710-006.

4. Fault Isolation
Subtask 31-33-00-810-051-A ** ON A/C NOT FOR ALL

A. If the FDIU (2TU) test gives the maintenance message FDIU:
(1) Make sure that the Circuit Breaker 8TU is closed.
(2) Do a check for 115 VAC at the FDIU (2TU) connectors AC/1 and AC/7 ASM 313301.
(3) If there is 115 VAC:
(a) Do a check and repair the wiring as necessary ASM 313400 between:

FDIU (2TU) connector AA/15A and AMU (1RN) connector AB/2B
FDIU (2TU) connector AA/15B and AMU (1RN) connector AB/2A.

(b) If the failure continues replace the FDIU [2TU] AMM 31-33-34-000-001 AMM 31-33-34-400-001.
(c) If the failure continues replace the AMU [1RN] AMM 23-51-34-000-001 AMM 23-51-34-400-001.
(4) If there is no 115 VAC:
(a) Do a check and repair the wiring as necessary ASM 313301 between:

CB 8TU and FDIU (2TU) connector AC/1
FDIU (2TU) connector AC/7 and ground
FDIU (2TU) connector AA/15J and ground
FDIU (2TU) connector AA/15K and ground
FDIU (2TU) connector AB/15K and ground
FDIU (2TU) connector AB/15J and ground
FDIU (2TU) connector AB/9B and SDAC 1 (1WV1), SDAC 2 (1WV2) at connector AA/10K
FDIU (2TU) connector AB/9E and CFDIU (1TW) connector AB/11D
FDIU (2TU) connector AB/9F and CFDIU (1TW) connector AB/11E
FDIU (2TU) connector AB/9J and CFDIU (1TW) connector AB/8B
FDIU (2TU) connector AB/9K and CFDIU (1TW) connector AB/8C.

Subtask 31-33-00-710-058-A ** ON A/C NOT FOR ALL

B. Do the test given in paragraph 3.A. again to check the correct operation
(no maintenance message display).

[Rev.8 from Aug 2018] 2026.04.04 04:29:59 UTC