Each engine has its own separate EEC. Each EEC has full authority over engine operation. In the normal mode, the EEC sets thrust by controlling EPR based on thrust lever position. EPR is commanded by positioning the thrust levers either automatically with the autothrottles, or manually by the flight crew.
Engine flameout protection is provided for an auto-relight and rain/hail ingestion. The auto-relight function is activated whenever an engine is at or below idle with the FUEL CONTROL switch in RUN. When the EEC detects an engine flameout, the respective engine ignitors are activated.
Fuel is supplied by fuel pumps located in the fuel tanks. The fuel flows through a spar fuel valve located in the main tank. It then passes through the first stage engine fuel pump where additional pressure is added. It flows through a fuel/oil heat exchanger where it is preheated. A fuel filter removes contaminants. If the filter becomes clogged, the filter will be bypassed, passing fuel directly to the engine. In that case, a Advisory EICAS message "ENG FUEL FILTER L/R" will be displayed.
When main tank fuel pump pressure is low, each engine can draw fuel from its corresponding main tank through a suction feed line that bypasses the pumps.
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Each engine has its own separate EEC. Each EEC has full authority over engine operation. In the normal mode, the EEC sets thrust by controlling EPR based on thrust lever position. EPR is commanded by positioning the thrust levers either automatically with the autothrottles, or manually by the flight crew.
Engine flameout protection is provided for an auto-relight and rain/hail ingestion. The auto-relight function is activated whenever an engine is at or below idle with the FUEL CONTROL switch in RUN. When the EEC detects an engine flameout, the respective engine ignitors are activated.
Fuel is supplied by fuel pumps located in the fuel tanks. The fuel flows through a spar fuel valve located in the main tank. It then passes through the first stage engine fuel pump where additional pressure is added. It flows through a fuel/oil heat exchanger where it is preheated. A fuel filter removes contaminants. If the filter becomes clogged, the filter will be bypassed, passing fuel directly to the engine. In that case, a Advisory EICAS message "ENG FUEL FILTER L/R" will be displayed.
When main tank fuel pump pressure is low, each engine can draw fuel from its corresponding main tank through a suction feed line that bypasses the pumps.