Installation of the Avionics Ventilation Skin Exchanger Isolation Valve

TASK 21-26-55-400-002-A
Installation of the Avionics Ventilation Skin Exchanger Isolation Valve

ZONE: 126
FIN: 24HQ

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
126	LATERAL AVIONIC COMPARTMENT
822

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
22	O-RING	AIPC 21-26-01-17-020
22	O-RING	AIPC 21-26-81-17-050

D. Referenced Information

REFERENCE	DESIGNATION
TASK 21-26-00-710-001-A	Operational Check of the Avionics Equipment Ventilation-System via MCDU
TASK 21-26-00-710-001-A-01	Operational Check of the Avionics Equipment Ventilation (without the CFDS)
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
Skin Exchanger Isolation Valve

3. Job Set-up

CAUTION: USE ONLY THE GROUND SERVICE NETWORK TO SUPPLY ELECTRICITY BECAUSE THE AVIONICS VENTILATION SYSTEM IS NOT SERVICEABLE. IF YOU ENERGIZE THE AIRCRAFT ELECTRICAL CIRCUITS WITHOUT THE VENTILATION SYSTEM YOU WILL CAUSE DAMAGE TO ELECTRICAL EQUIPMENT.

Subtask 21-26-55-860-052-A

A. Aircraft Maintenance Configuration
(1) Make sure that the ground service network is energized (Ref. AMM TASK 24-42-00-861-001).

Subtask 21-26-55-010-059-A

B. Get Access
(1) Make sure that the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE is in position at the access door 822.
(2) Make sure that the access door 822 is opened.

Subtask 21-26-55-865-054-A

C. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/AVNCS VENT/CTL	6HQ	D06

Subtask 21-26-55-210-051-A

D. Visual Inspection
(1) Make sure that the clamps, the flexible sleeve and the valve are in good condition; replace if necessary.

4. Procedure
Subtask 21-26-55-420-052-B

A. Installation of the Skin Exchanger Isolation Valve
(1) Remove the PLUG-BLANKING from each disconnected line end.
(2) Install the flexible sleeve (26) on the duct (28).
(3) Put the new AIPC 21-26-01-17-020 O-RING (22) or AIPC 21-26-81-17-050 O-RING (22) in the groove of the duct (20).
(4) Install the valve (23) in the flexible sleeve (26).

NOTE: The arrow that indicates the air flow points up.

(5) Make sure that the valve (23) is in the correct angular position . The electrical cable must not be too tight or too loose.
(6) Install the clamp (21) and tighten to the torque value which is indicated on the clamp.
(7) Put the flexible sleeve (26) in position.
(8) Install and tighten the clamps (25) and (27).

NOTE: Use the clamps (25) and (27) kept during the removal procedure.

(9) Remove the CAP-BLANKING from each electrical connector and receptacle.
(10) Make sure that all the electrical connections are clean and in the correct condition.
(11) Connect the electrical connector (24).

Subtask 21-26-55-865-055-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/AVNCS VENT/CTL	6HQ	D06

Subtask 21-26-55-710-051-A

C. Do this Test
(1) Do an operational test of the ventilation system of the avionics equipment (Ref. AMM TASK 21-26-00-710-001).

NOTE: As an alternative procedure, you can do this operational test without the CFDS.

5. Close-up
Subtask 21-26-55-410-052-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the access door 822.
(3) Remove the access platform(s).

Subtask 21-26-55-862-053-A

B. De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

[Rev.10 from 2021] 2026.04.02 06:11:09 UTC