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757 MAINTENANCE MANUAL
 (b)  Make sure the INOP light goes off.
 S 214-024
 (3)  
Feel for the airflow from around the check valve.

 (a)  
Small leaks are permitted.

 (b)  
You must repair a large leak.

 F.
Put the airplane back to its usual condition

 S 414-026
 (1)  
If the left check valve was installed:

 (a)  
Install the left sidewall lining panel in the forward end of the forward cargo compartment.

 S 414-027
 (2)  
If the right check valve was installed:

 (a)  
Install the access panel for the right recirculation filter, which is in the aft bulkhead of the forward cargo compartment.

 S 414-028
 (3)
Close the No. 1 cargo compartment door, 821 (AMM 06-46-00/201).

 S 864-029

 (4)  
Remove the DO-NOT-OPERATE tag from the L and R PACK selectors, on the P5 panel.

 S 864-030

 (5)  
Remove the electrical power, if it is not necessary
 (AMM 24-22-00/201).

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757 MAINTENANCE MANUAL
 RECIRCULATION AIR CHECK VALVE - INSPECTION/CHECK
________________________________________________
 1.  General_______
 A.  This procedure has instructions to make sure the left and right recirculation check valves operate correctly and are not damaged or worn out.
 TASK 21-25-03-206-001
 2.  Do the Recirculation Air Check Valve Inspection (Fig. 601)_______________________________________________
 A.  References
 (1)  
21-25-03/401, Recirculation Air Check Valve

 B.  
Access

 (1)  
Location Zones 121 Forward cargo compartment (Left) 126 Area aft of the forward cargo compartment (Right)

 C.  
Examine the Recirculation Air Check Valve

 S 026-002
 (1)
Remove the applicable (left or right) check valve (Ref 21-25-03).

 S 216-004

 (2)  
Look for these conditions on the check valve:

 (a)  
A part of the check valve is not installed.

 (b)  
The housing is cracked or corroded.

 (c)  
The flappers do not move freely.

 (d)  
The area of the flapper that contacts the stop pin is less than .03 inches in thickness.

 (e)  
The surfaces beween the flapper and the housing has carbon deposits or is not equally worn.

 (f)  
The hinge pin can come out of the flappers or the housing.

 S 906-005
 (3)  
If any of these conditions are found, then install a new check valve (Ref 21-25-03).

 S 426-006

 (4)  
If none of these conditions are found, then install the same check valve (Ref 21-25-03).

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757
MAINTENANCE MANUAL

RECIRCULATION AIR CHECK VALVE

Recirculation Air Check Valve
Figure 601

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757 MAINTENANCE MANUAL
 VENTILATION SYSTEM - DESCRIPTION AND OPERATION
______________________________________________
　
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