*
Engine fire switch
*
EEC.
When one of the cutoff solenoids energizes, hydraulic pressure closes the minimum pressure and shutoff valve. During autostarts, the EEC can energize the EEC cutoff solenoid to close the valve.
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ENGINE FUEL CONTROL -FMU -FUNCTIONAL DESCRIPTION
The windmill bypass valve protects the FMU from high pressures when the engine is turning, but not operating (starter engaged or windmilling). When the engine is operating, the hydraulic pressure that holds the minimum pressure and shutoff valve closed is removed. This pressure goes to hold the windmill valve closed.
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ENGINE FUEL CONTROL -FMU -FUNCTIONAL DESCRIPTION
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ENGINE FUEL CONTROL -FMU -ENGINE FUEL SHUTOFF VALVE CONTROL
General
The fuel control switch controls relays in the P110 to open or close the engine fuel shutoff valve (SOV). The SOV gets power to open and to close from the captain’s flight instrument bus.
Control
When the fuel control switch is in the RUN position, power goes through the generator control/ignition relay to the engine relay unit (ERU). The ERU divides the power and sends it to EEC channels A and B. This causes the EEC to open the SOV.
When the fuel control switch is in the CUTOFF position, power goes through the generator control/ignition relay to the FMU to close the SOV. The EEC does not control the closing of the SOV.
The fire switch must be in the NORMAL position to permit power to go through the P110 to operate the SOV. When the fire switch is in the FIRE position, power to close the SOV goes directly to the SOV. It does not go through the P110.
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ENGINE FUEL CONTROL -FMU -ENGINE FUEL SHUTOFF VALVE CONTROL
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D633W101-BEJ Sep 05/2002
ENGINE FUEL CONTROL -SERVO FUEL HEATER
General
The servo fuel heater prevents ice formation in the servo fuel under extremely cold conditions. This permits the engine to operate safely to inlet fuel temperatures of minus 65F (minus 54C). The servo fuel heater attaches to the left side of the HPC case below the fuel/oil cooler (8:00 position).
Functional Description
The servo fuel heater receives high pressure servo fuel from the fuel pump. It heats it with engine oil, cleans it with the filter element, and supplies it to these components:
*
Fuel metering unit
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本文链接地址：777 AMM 飞机维护手册 发动机和燃油控制 Engine Fuel and Control PW 777 AIRCRAFT MAINTENANCE MANUAL(20)
