Installation of the Check Valve

TASK 21-26-41-400-001-A
Installation of the Check Valve

ZONE: 128
FIN: 2140HM

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
128	REAR AVIONIC COMPARTMENT
824

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
12	O-RING	AIPC 21-26-01-08-030
12	O-RING	AIPC 21-26-81-08-050

D. Referenced Information

REFERENCE	DESIGNATION
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
TASK 52-41-00-410-002-A	Close the Avionics Compartment Doors after Access
Check 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 21-26-41-860-050-A

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

Subtask 21-26-41-865-051-A

B. 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
49VU	AIR COND/AVNCS VENT/CTL	5HQ	D05
122VU	AIR COND/AVNCS/VENT/MONG	3HQ	Y17
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AE02
** ON A/C ALL
123VU	AVNCS VENT/BLOWER/FAN	1HQ	AD10
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AC04

Subtask 21-26-41-010-051-A

C. Get Access
(1) Make sure that the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE is in position at the access door 824.
(2) Make sure that the access door 824 is open.

4. Procedure
Subtask 21-26-41-420-052-G

A. Installation of the Check Valve
(1) Remove the PLUG-BLANKING from each disconnected line end.
(2) Install the flexible sleeve (3).
(3) Put the check valve (4) in position.

NOTE: The arrow that indicates the air flow points to the left.

(4) Install the washers (5), the screws (6) and tighten.
(5) Install the clamps (2) and tighten.

NOTE: Use the clamps (2) kept during the removal procedure.

(6) Install the flexible sleeve (7).
(7) Install the new AIPC 21-26-01-08-030 O-RING (12) or AIPC 21-26-81-08-050 O-RING (12) in the fan (13) groove.
(8) Put the duct (10) in position.
(9) Install the clamp (9). Do not fully tighten at this time.
(10) Install the clamps (8) and tighten.

NOTE: Use the clamps (8) kept during the removal procedure.

(11) Install the drain hose (15) to the duct (10).
(12) Install the clamp (14) and tighten it.
(13) Make sure that the O-ring (12) is correctly installed in the fan (13) groove.
(14) Install the clamp (11) and torque them to the value given on the clamp.
(15) Tighten the clamp (9).

5. Close-up
Subtask 21-26-41-410-050-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 824 (Ref. AMM TASK 52-41-00-410-002).
(3) Remove the access platform(s).

Subtask 21-26-41-865-052-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
49VU	AIR COND/AVNCS VENT/CTL	5HQ	D05
122VU	AIR COND/AVNCS/VENT/MONG	3HQ	Y17
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AE02
** ON A/C ALL
123VU	AVNCS VENT/BLOWER/FAN	1HQ	AD10
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AC04

Subtask 21-26-41-862-051-A

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

[Rev.10 from 2021] 2026.04.02 06:11:03 UTC