Skin Air-Inlet Valve Jammed or Air-Inlet Check Valve Failure

TASK 21-26-00-810-840-A
Skin Air-Inlet Valve Jammed or Air-Inlet Check Valve Failure

1. Possible Causes

CHECK VALVE-AIR INLET, AVNCS VENT [2150HM]
wiring
VALVE-SKIN AIR INLET, AVNCS VENT [15HQ]
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 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 21-26-52-000-001	Removal of the Avionics-Ventilation Skin Air-Inlet-Valve
AMM 21-26-52-400-001	Installation of the Avionics-Ventilation Skin Air-Inlet-Valve
AMM 21-26-56-000-001	Removal of the Air Inlet Check Valve
AMM 21-26-56-280-002	Operational Check of Air Inlet Check Valve
AMM 21-26-56-400-001	Installation of the Air Inlet Check Valve

3. Fault Confirmation
Subtask 21-26-00-865-077-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 21-26-00-710-119-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 21-26-00-810-097-A

A. If the test is OK:

Do the operational check of the air inlet check-valve (2150HM) AMM 21-26-56-280-002.

(1) If the result of the operational check is not correct:

Replace the CHECK VALVE-AIR INLET, AVNCS VENT [2150HM] AMM 21-26-56-000-001 and AMM 21-26-56-400-001.

(2) If the result of the operational check is correct:

Do a check of the wiring ASM 212603 between the AEVC (10HQ) and the skin air-inlet valve (15HQ):
. Pin AA/4B and pin A/C
. Pin AA/4A and pin A/A
. Pin AB/4B and pin A/M
. Pin AB/4A and pin A/J.

(a) If the wiring is not correct:

Repair the wiring.

(b) If the wiring is correct:

Do a check of the wiring ASM 212603 between the SDAC1 (1WV1) and SDAC2 (1WV2), and the skin air-inlet valve (15HQ):
. Pin AD/11C and pin A/M
. Pin AD/10F and pin A/J.

1 If the wiring is not correct:

Repair the wiring.

2 If the wiring is correct:

Replace the VALVE-SKIN AIR INLET, AVNCS VENT [15HQ] AMM 21-26-52-000-001 and AMM 21-26-52-400-001.

3 If the fault continues:

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

Subtask 21-26-00-710-120-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:24:39 UTC