Closure of the Avionics Skin Air Inlet and Outlet Valves after Failure of the Cabin Pressure Controller on Ground

TASK 21-26-00-810-831-A
Closure of the Avionics Skin Air Inlet and Outlet Valves after Failure of the Cabin Pressure Controller on Ground

1. Possible Causes

PRESS CONT 1 [11HL]
PRESS CONT 2 [12HL]

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 21-31-34-000-001	Removal of the Cabin Pressure Controller
AMM 21-31-34-400-001	Installation of the Cabin Pressure Controller

3. Fault Confirmation
Subtask 21-26-00-710-102-A

A. Test
(1) Do an operational test of the avionics equipmemt ventilation from the Multipurpose Control and Display Unit (MCDU) AMM 21-26-00-710-001.
(a) Make sure that the avionics equipment ventilation system operates correctly.
(b) Make sure that the skin air inlet and outlet valves (15HQ and 22HQ) stay closed.

4. Fault Isolation
Subtask 21-26-00-810-084-A

A. If the test confirms the fault:
(1) Remove the two cabin pressure controllers (11HL and 12HL) AMM 21-31-34-000-001.
(2) Make sure that the skin air inlet and outlet valves (15HQ and 22HQ) open.
(3) Install the cabin pressure controller 1 (11HL) AMM 21-31-34-400-001.
(a) If the skin air inlet and outlet valves close:
1 Replace the PRESS CONT 1 [11HL] AMM 21-31-34-000-001 and AMM 21-31-34-400-001.
2 Install the cabin pressure controller 2 (12HL) AMM 21-31-34-400-001.
(b) If the skin air inlet and outlet valves stay open:
1 Install the cabin pressure controller 2 (12HL) AMM 21-31-34-400-001.
2 Make sure that the skin air inlet and outlet valves close.
3 Replace the PRESS CONT 2 [12HL] AMM 21-31-34-000-001 and AMM 21-31-34-400-001.

Subtask 21-26-00-710-103-A

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

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