Loss of the Information from the EIUs

TASK 21-26-00-810-822-A
Loss of the Information from the EIUs

1. Possible Causes

wiring
EIU-1 [1KS1]
EIU-2 [1KS2]
AEVC [10HQ]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 21-26-00-710-001	Operational Check of the Avionics Equipment Ventilation-System via MCDU
AMM 21-26-00-710-008	Operational Test to Read the CFDS for CLASS 3 Faults of the AEVC
AMM 21-26-00-710-009	Operational Test to Read the CFDS for LAST LEG REPORT of the AEVC
ASM 212602
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)
ASM 732509
AMM 73-25-34-000-040	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-000-802	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-040	Installation of the Engine Interface Unit (EIU)
AMM 73-25-34-400-802	Installation of the Engine Interface Unit (EIU)

3. Fault Confirmation
Subtask 21-26-00-865-066-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	AIR COND/AVNCS/VENT/MONG	3HQ	Y17

Subtask 21-26-00-710-070-A

B. Test
(1) Do a reset of the AEVC (10HQ).
(a) Open the circuit breaker AIR COND/AVNCS/VENT/MONG (3HQ).
(b) Wait for five seconds.
(c) Close the circuit breaker AIR COND/AVNCS/VENT/MONG (3HQ).
(2) Do the operational test of the avionics equipment ventilation from the Multipurpose Control and Display Unit (MCDU) AMM 21-26-00-710-001.
(3) Read the LAST LEG REPORT of the AEVC AMM 21-26-00-710-009.
(4) Read the CLASS 3 faults of the AEVC AMM 21-26-00-710-008.

4. Fault Isolation
Subtask 21-26-00-810-060-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK EIU - AEVC INTFC:

Make sure that there is no ground signal at pins AB/10A and AB/11A of the AEVC (10HQ) ASM 212602.

(1) If there is a ground signal:

Do a check of the wiring ASM 212602 and ASM 732509 between:
. Pin AB/10A of the AEVC (10HQ) and pin AB/1G of the EIU-1 (1KS1)
. Pin AB/11A of the AEVC (10HQ) and pin AB/1G of the EIU-2 (1KS2).

(a) If the wiring is not correct:

Repair the related wiring .

(b) If the wiring is correct and the fault continues:
1 If the ground signal is at the pin AB/10A of the AEVC (10HQ):

Replace the EIU-1 [1KS1] AMM 73-25-34-000-040 and AMM 73-25-34-400-040.

2 If the ground signal is at the pin AB/11A of the AEVC (10HQ):

Replace the EIU-2 [1KS2] AMM 73-25-34-000-040 and AMM 73-25-34-400-040.

(2) If there is no ground signal:

Replace the AEVC [10HQ] AMM 21-26-34-000-001 and AMM 21-26-34-400-001.

Subtask 21-26-00-810-060-F ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK EIU - AEVC INTFC:

Make sure that there is no ground signal at pins AB/10A and AB/11A of the AEVC (10HQ) ASM 212602.

(1) If there is a ground signal:

Do a check of the wiring ASM 212602 and ASM 732509 between:
. Pin AB/10A of the AEVC (10HQ) and pin AB/1G of the EIU-1 (1KS1)
. Pin AB/11A of the AEVC (10HQ) and pin AB/1G of the EIU-2 (1KS2).

(a) If the wiring is not correct:

Repair the related wiring .

(b) If the wiring is correct and if the fault continues:
1 If the ground signal is at the pin AB/10A of the AEVC (10HQ):

Replace the EIU-1 [1KS1] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.

2 If the ground signal is at the pin AB/11A of the AEVC (10HQ):

Replace the EIU-2 [1KS2] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.

(2) If there is no ground signal:

Replace the AEVC [10HQ] AMM 21-26-34-000-001 and AMM 21-26-34-400-001.

Subtask 21-26-00-710-072-A

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

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