Removal of the Avionics Ventilation Skin Exchanger Outlet Bypass Valve

TASK 21-26-55-000-003-A
Removal of the Avionics Ventilation Skin Exchanger Outlet Bypass Valve

ZONE: 125
FIN: 23HQ

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
No specific	AR	CAP - BLANKING
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
125	LATERAL AVIONIC COMPARTMENT
812

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
Skin Exchanger Outlet Bypass 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 21-26-55-861-054-A

A. Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).

Subtask 21-26-55-865-056-A

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/AVNCS VENT/CTL	6HQ	D06
49VU	AIR COND/AVNCS VENT/CTL	5HQ	D05

Subtask 21-26-55-010-053-A

C. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position at the access door 812.
(2) Open the access door 812.

4. Procedure
Subtask 21-26-55-020-053-A

A. Removal of the Skin Exchanger Outlet Bypass Valve
(1) Disconnect the electrical connector (36) from the valve (37).
(2) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(3) Remove the bolt (31) and the nut (30).
(4) Loosen the two screws (33).
(5) Remove the clamp (39) and the valve (37).
(6) Discard the O-ring (38).
(7) Put the PLUG-BLANKING in each disconnected line end.
(8) Remove the clamp (35) and the grid (34).

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