777 AMM 飞机维护手册 发动机滑油 Engine Oil PW 777 AIRCRAFT MAINTENANCE MANUAL(10)

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No. 3 Bearing Compartment Breather Restrictor Valve
The No. 3 bearing compartment breather restrictor valve controls the flow of breather air (bearing seal pressurization air) out of the bearing compartment.
The 12th stage air pressure that operates the valve comes from the No. 3 bearing buffer air cooler manifold.
When engine power increases, the 12th stage air closes the No. 3 bearing compartment breather restrictor valve. This holds higher breather pressure in the bearing compartment to help prevent failure of the carbon seals. A small fixed orifice lets some breather air flow through the valve.
A pop-out indicator shows when the valve is in the closed position.
EFFECTIVITY BEJ ALL  79-20-00 
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D633W101-BEJ  Sep 05/2002 

 

OIL -DISTRIBUTION -DEOILER AND NO. 3 BEARING COMPARTMENT BREATHER RESTRICTOR VALVE

EFFECTIVITY BEJ ALL  79-20-00 
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D633W101-BEJ  Sep 05/2002 

OIL -DISTRIBUTION -DEOILER VENT DUCT

Purpose
The deoiler vent duct sends breather air overboard from the main gearbox deoiler.
Location
The deoiler vent duct attaches to the aft side of the engine main gearbox. It extends from the main gearbox to the bottom of the LPT case. The thrust reverser halves close around the opening of the duct.
EFFECTIVITY BEJ ALL  79-20-00 
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D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

OIL -DISTRIBUTION -DEOILER VENT DUCT

EFFECTIVITY BEJ ALL  79-20-00 
Page 23 
D633W101-BEJ  Sep 05/2002 

PW4000 SERIES ENGINES

777 AIRCRAFT MAINTENANCE MANUAL

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79-20-00

Page 24 D633W101-BEJ Sep 05/2002

OIL -DISTRIBUTION -FUNCTIONAL DESCRIPTION

Oil Pressurization and Filtering
The engine oil flows from the engine oil tank to the lubrication and scavenge oil pump. The pressure stage of the pump supplies pressurized oil to the main oil filter housing.
Oil flows through the primary filter and then through the secondary filter. The oil filter differential pressure switch monitors the primary filter. If the primary filter becomes clogged, the main oil filter pressure relief valve opens. This lets oil flow directly to the secondary filter element.
Oil Cooling
The oil flows to the engine air/oil heat exchanger and valve from the main oil filter.
If the fuel temperature is too high, the EEC sends a signal to the valve torque motor. Servo fuel pressure starts to open the valve. Two rotary variable transformers send valve position signals to the EEC. The EPCS maintenance page shows the valve position as a percent of full open.
Fan air cools the engine oil at high engine power levels. At low power levels, 2.5 bleed air cools the engine oil.
　
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