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A

757 MAINTENANCE MANUAL
AIR CONDITIONING
CONTROL MODULE
P11 PANEL

SEE A
P5 PANEL
P61 PANEL
FLIGHT COMPT

AIR CONDITIONING CONTROL MODULE
A
Recirculation System
Figure 1 (Sheet 1)

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757
MAINTENANCE MANUAL

RECIRCULATION  RECIRCULATIONSEE B
AIR FAN AIR CHECK VALVE SEED SEEF
SEE  C 
RECIRCULATION 
AIR CHECK VALVE  FILTERS 
RECIRCULATION  SEE  F  SEE  E  FILTER SUPPORT 
AIR FAN 
SEE  G
MIX MANIFOLD 
B  MIX 
MANIFOLD 
FILTER 
SUPPORT 
FILTERS 
SEE  E 
ELECTRICAL 
CONNECTION 
C  RIGHT RECIRCULATION AIR FAN 
D 

INBD 
HIGH 
EFFICIENCY 
FILTER  PREFILTER  FWD 
RECIRCULATION AIR FILTERS  RECIRCULATION AIR CHECK VALVE  LEFT RECIRCULATION AIR FAN 
E  F  G 

Recirculation System
Figure 1 (Sheet 2)

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MAINTENANCE MANUAL

 B.  Recirculation Air Filters
_________________________
 (1)  
Physical Description

 (a)  
A pre-filter and high efficiency particulate filter are both encased in an aluminum frame. The right recirculation filters mount to the right of the mix manifold at the rear of the forward cargo compartment, upstream of the fan. The left filter assembly mounts to the left and just upstream of the mix manifold. 1) Pre-filter

 a)  The pre-filter is a particulate filter. It contains an aluminum frame around a fiberglass pad. The 1.5 pound filter traps the largest of the contaminant particles. The pre-filter is rated at 1000 cpm airflow and has a minimum arrestance of 60%.
 2) High Efficiency Particulate (HEP) Filter
 a)  The HEP filter is a glass filter with an aluminum frame. The 3 pound filter, rated at 1000 cpm airflow, has a minimum arrestance of 95% for smoke particles 0.3 microns or larger.
 C.  Recirculation Air Check Valve
_____________________________
 (1)  
Physical Description

 (a)  
A recirculation air check valve is located just downstream of each recirculation fan. The check valve is 7 inches in diameter and contains a seat/flapper assembly, centered and riveted into the check valve housing. The seat/flapper assembly contains two semi-circular flappers hinged about a central pin. A stop pin provides a limit to prevent over-travel of the flappers.

 (2)  
Function

 (a)  
Airflow, in the direction of the arrow on the valve housing, opens the flappers until they come in contact with the stop pin. Reverse airflow closes the check valve flappers against the seat. This action prevents air from passing back through the system, into the cargo compartment and forward equipment center.

 3.  Operation (Fig. 2 and 3)
_________
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MAINTENANCE MANUAL

GROUND CONDITIONEDAIR CONNECTOR
Right Recirculation Fan Operation SchematicFigure 2
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