Loss of the Automatic Control and Monitoring of the Valves and Fans

TASK 21-26-00-810-801-A
Loss of the Automatic Control and Monitoring of the Valves and Fans

1. Possible Causes

CARTRIDGE-AVNCS VENT FILTER [2082HM]
AEVC [10HQ]
wiring between the AEVC pin AA/1D and the ground terminal
C/B-AIR COND/AVNCS/VENT/MONG [3HQ]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 24-00-00-810-803-A	Circuit Breaker Tripped and/or C/B TRIPPED Warning
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 212601
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 21-26-43-600-016	Discard Demister Filter Element and Filter Cartridge (LE BOZEC)
AMM 21-26-43-920-001	Discard the Filter Cartridge (PALL)

3. Fault Confirmation
Subtask 21-26-00-865-050-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 21-26-00-710-050-A

B. Test
(1) Do the 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 21-26-00-810-050-D ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message NO RESPONSE:

make sure that the avionics ventilation filter is not dirty. If necessary, replace the CARTRIDGE-AVNCS VENT FILTER [2082HM] AMM 21-26-43-920-001.

(1) If the fault continues:

Do a check of the status of the circuit breaker (3HQ).

(a) If the circuit breaker (3HQ) is closed:

Do a check for 28VDC at pin AA/1A of the AEVC (10HQ) ASM 212603.

1 If there is 28VDC:

Do a check for a ground signal at pin AA/1D of the AEVC (10HQ) ASM 212601.

a If there is a ground signal:

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

b If there is no ground signal:

Repair the wiring between the AEVC pin AA/1D and the ground terminal.

2 If there is no 28VDC:

Do a check of the wiring between the AEVC pin AA/1A and the circuit breaker (3HQ) ASM 212603.

a If there is no continuity:

Repair the related wiring.

b If there is continuity:

Replace the C/B-AIR COND/AVNCS/VENT/MONG [3HQ] .

(b) If the circuit breaker (3HQ) is open:

Do the procedure (Ref. TSM TASK 24-00-00-810-803).

1 If the fault continues:

Replace the C/B-AIR COND/AVNCS/VENT/MONG [3HQ] .

2 If the fault continues:

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

Subtask 21-26-00-810-050-E ** ON A/C NOT FOR ALL