FLIGHT COMPARTMENT B Cargo Compartment Conditioned Air Distribution - Component Location Figure 1 (Sheet 1)
D09304
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A

747-400
MAINTENANCE MANUAL

FORWARD CARGO AIR CONDITIONING
FLOW REGULATING VALVE

C

LOWER LOBE
CARGO COND AIR
FLOW RATE

OFF
LOW A FWD FT  FWD AFT  HIGH 
BOTH 

LOWER LOBE CARGO CONDITIONED
AIR FLOW RATE SELECTOR (P461)

D

Cargo Compartment Conditioned Air Distribution - Component Location
Figure 1 (Sheet 2)

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D09311
A

747-400
MAINTENANCE MANUAL

AFT CARGO AIR CONDITIONING FLOW REGULATING VALVE
SEE E
MAIN DISTRIBUTION MANIFOLD SEE F
RIGHT WHEEL WELL (REF)FWD
AFT CARGO AIR CONDITIONING
FLOW REGULATING VALVE

E

Cargo Compartment Conditioned Air Distribution - Component Location Figure 1 (Sheet 3)
D09417
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A
747-400 MAINTENANCE MANUAL
MIX BAY
RIGHT WING GEAR WHEEL WELL (REF)
FORWARD CABIN SHUTOFF VALVE
SEE G
PACK 3 OUTLET DUCT
AFT CABIN SHUTTOFF VALVE
FWD
SEE H
PACK 2 OUTLET DUCT
MAIN DISTRIBUTION MANIFOLD
F

FWD
FORWARD CABIN SHUTOFF VALVE AFT CABIN SHUTOFF VALVE GH
Cargo Compartment Conditioned Air Distribution - Component Location Figure 1 (Sheet 4)
D09444
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A
747-400
MAINTENANCE MANUAL

 B.  The cabin shutoff valves close off the conditioned air supply to the main distribution manifold and allow all of the air from the applicable pack to be diverted to the respective cargo compartment.
 C.  The applicable valve will be open when the cargo conditioned air flow rate is set to OFF or LOW and will be closed when the flow rate is set to HIGH.
 D.  The valves are 9-inch diameter disk type valves that are electrically operated by 115 volts ac power.
 E.  The valves have a position indicator on the valve actuator. The valve can also be manually positioned by rotating the manual overide knob on the valve actuator. The electrical connector must be removed when operating the valve manually.
 4.  Operation (Fig. 2)
_________
 A.  Functional Description
 (1)  
The EICAS ECS maintenance page shows the position of the flow regulating valves and the cabin shutoff valves. It also shows the flow mode (HI, LOW, or OFF) of the aft or forward cargo compartments.

 (2)  
Conditioned air flow rate to the forward or aft cargo compartment is adjusted by varying the position of the applicable cargo air conditioning flow regulating valves and the cabin shutoff valves.

 (a)  
When the flow selector switch is set to OFF, the cabin shutoff valves will be open and and the flow regulating valves will be closed. All of the pack air will go to the main and upper deck areas.

 (b)  
When the flow selector is set to LOW (FWD, AFT, or BOTH), the applicable cabin shutoff valve(s)will be open and the flow regulating valve(s) will open to the intermediate position. A portion of the pack air flow will therefore be diverted to the cargo compartment(s).
　
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