*
Start selector is in the START position
*
EEC maintenance switch is in the TEST position.
When the engine is running, the PMA supplies power to the EEC. If the PMA has a failure, the ELMS supplies power to the EEC.
ERU
The ERU contains switches that control power to engine electrical loads. The EEC controls these switches. The ERU also does these functions:
*
Receives a single signal from some engine components and makes two signals for the two channels of the EEC
*
Receives two signals from the EEC for some components and makes them into a single signal
*
Monitors voltage to the ignition exciters
EFFECTIVITY
BEJ ALL
* Monitors current for P2/T2 probe heat.
EEC
The EEC is a two channel computer that controls the operation of the engine. Each channel can completely control the operation of the engine. The EEC controls the engine thrust in two modes. You use the EEC mode switch for mode selection. In the normal mode, engine thrust is set with EPR. In the alternate mode, engine thrust is set with N1.
The EEC also does these functions:
*
Controls engine components
*
Gets position and fault data from engine components
*
Monitors engine sensors.
When you move the fuel control switch from RUN to CUTOFF, the EEC resets. When the EEC resets, it writes all fault data in its non-volatile memory (NVM). The reset also sets the initial conditions for the EEC hardware and software.
FMU
The EEC controls the metering valve in the FMU to supply fuel flow for combustion. The EEC also sends a signal to the minimum pressure and shutoff valve (SOV) in the FMU to start and stop fuel flow. The EEC gets position feedback for the two valves.
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ENGINE FUEL CONTROL -GENERAL DESCRIPTION
When you move the fuel control switch to the RUN position, the EEC controls the power to open the SOV. When you move the fuel control switch to the CUTOFF position, the ELMS sends power to close the SOV. The valve also closes when you pull the engine fire switch.
Engine Data Interface Unit (EDIU)
The engine data interface unit (EDIU) changes the ARINC 429 format data from the EEC to ARINC 629. It also changes ARINC 629 data to ARINC 429. This lets the EEC transmit data to and get data from airplane systems.
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ENGINE FUEL CONTROL -GENERAL DESCRIPTION
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ENGINE FUEL CONTROL -ENGINE COMPONENT LOCATIONS
Component Locations -Engine
Most of the engine fuel control components are on the left side of the engine. These are the components:
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