777 AMM 飞机维护手册 动力装置 Power Plant PW 777 AIRCRAFT MAINTENANCE MANUAL(21)

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Actuators
There are four cowl opening actuators on each engine. Each fan cowl and each T/R half has an actuator. When the actuators receive hydraulic pressure, they extend to open the cowls. When hydraulic pressure is removed, the actuators retract and the cowls close.
The actuators are also safety devices. Flow control valves in the actuators limit the flow of hydraulic fluid in the closing direction. This prevents the fan cowls and T/Rs from closing quickly.
EFFECTIVITY BEJ ALL  71-12-00 
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D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

PDOS -GENERAL DESCRIPTION

EFFECTIVITY BEJ ALL  71-12-00 
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D633W101-BEJ  Sep 05/2002 

PDOS -COMPONENT LOCATIONS

The PDOS has these components:
*
Pump/power pack

*
Cowl opening actuators

*
Hydraulic cowl opening flexhoses

*
Actuation and control switches.

Pump/Power Pack
Each engine has one pump/power pack. The pump/power pack is under the right half of the forward No. 3 strut fairing.
Fan Cowl Opening Actuators
The fan cowl opening actuators are under the fan cowls. The top of each actuator attaches to an actuator bracket on the fan cowl. The bottom of each actuator attaches to the engine fan case.
Thrust Reverser Cowl Opening Actuators
The thrust reverser (T/R) cowl opening actuators are under the T/Rs. The top of each actuator attaches to the engine strut. The bottom of each actuator attaches to the inner wall of the T/R.
Hydraulic Cowl Opening Flex Hoses
The hydraulic cowl opening flex hoses permit the necessary movement of the PDOS hydraulic supply lines. The fan cowl flex hoses connect the PDOS hydraulic tubes on the fan case to the actuators and the strut. The T/R flex hoses connect the PDOS hydraulic tubes in the strut to the actuators.
Actuation and Control Switches
The fan cowl actuation and control switches are on the inlet cowl at the 4:00 and 8:00 positions.
The T/R actuation and control switches are on the aft bulkhead of the inlet cowl near the fan cowl switches.
EFFECTIVITY BEJ ALL  71-12-00 
Page 6 
D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

PDOS -COMPONENT LOCATIONS

EFFECTIVITY BEJ ALL  71-12-00 
Page 7 
D633W101-BEJ  Sep 05/2002 

PDOS -ACTUATION AND CONTROL SWITCHES
Actuation and Control Switches
Two actuation and control switches are on each side of the inlet cowl. Each actuation and control switch has an UP button and a DOWN button. The buttons are a momentary-action type.
EFFECTIVITY BEJ ALL  71-12-00 
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D633W101-BEJ  Sep 05/2002 
　
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