PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
ENGINE FUEL CONTROL -PMA
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ENGINE FUEL CONTROL -EEC AND PROGRAMMING PLUG
General
The EEC is a computer that controls the operation of the engine. It attaches to the lower-left fan case with shock mounts. The housing contains two electronic channels that are physically separated internally. The unit weighs about 51 lb (23 kg). Natural convection cools the EEC.
Electrical Connections
Each channel of the EEC has seven electrical connections, three on each side and one on the bottom. Both channels share the inputs of the two connections on the top of the EEC. These are the programming plug and test connector.
The test connection is for testing the EEC with special shop equipment.
Programming Plug
The programming plug selects the proper software in the EEC for the thrust rating of the engine. The plug attaches to engine fan case with a lanyard. When you remove the EEC, the plug remains with the engine.
Pneumatic Connections
Each channel of the EEC has three pneumatic connections on the bottom of the EEC. Transducers inside the EEC supply the related and opposite EEC channel with a signal in proportion to the pressure. These are the pneumatic connections:
*
PAMB -ambient pressure
*
PB -burner pressure
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P2.5 -LPC exit pressure
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P2 -fan inlet pressure (EPR)
*
PSPARE -spare connection
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P5 -LPT exit pressure (EPR) (P4.95).
Training Information Point
The engine wires have these colors to show their purpose:
*
Blue -EEC channel A signals
*
Green -EEC channel B signals
*
Gray -non-EEC circuits
*
Yellow -thermocouple signals.
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ENGINE FUEL CONTROL -EEC AND PROGRAMMING PLUG
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D633W101-BEJ Sep 05/2002
PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
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Page 24 D633W101-BEJ Sep 05/2002
ENGINE FUEL CONTROL -EEC -FUNCTIONAL DESCRIPTION
General
The EEC is a two-channel computer that controls the operation of the engine. It has two channels, but only one is in control at a time (primary channel). The primary channel changes each time you start the engine.
Power
The EEC gets power from the ELMS or the permanent magnet alternator (PMA).
The ELMS supplies power to the EEC when one or more of these conditions exist:
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