No Transmission by the ARINC 429 Bus

TASK 21-26-00-810-826-A
No Transmission by the ARINC 429 Bus

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 212602
ASM 212603
AMM 21-26-34-000-001	Removal of the Avionics Equipment Ventilation Computer (AEVC)
AMM 21-26-34-400-001	Installation of the Avionics Equipment Ventilation Computer (AEVC)
AMM 31-32-00-869-002	Procedure for the Class 3 Fault Reading
ASM 313206
AMM 31-32-34-000-001	Removal of the CFDIU
AMM 31-32-34-400-001	Installation of the CFDIU

3. Fault Confirmation
Subtask 21-26-00-740-050-A

A. Test
(1) On the CFDS MENU page, get access to the AVIONICS STATUS page AMM 31-32-00-869-002.

4. Fault Isolation
Subtask 21-26-00-810-065-A

A. If the test gives the maintenance message NO AEVC DATA:

Do a check of the wiring ASM 212602 and ASM 313206 between:
. Pin AB/12A of the AEVC (10HQ) and pin AB/10A of the CFDIU (1TW)
. Pin AB/13A of the AEVC (10HQ) and pin AA/3D of the CFDIU (1TW)
. Pin AB/14A of the AEVC (10HQ) and pin AA/3E of the CFDIU (1TW).

(1) If the wiring is not correct:

(2) If the wiring is correct:

(a) If the fault continues:

Do a check of the wiring ASM 212603 between pin 2 of the AIR COND/AVNCS/VENT/MONG circuit breaker (3HQ) and pin AA/1A of the AEVC (10HQ).

1 If the wiring is not correct:

2 If the wiring is correct:

Subtask 21-26-00-740-051-A

B. Do the operational test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:24:38 UTC