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PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
ENGINE FUEL INDICATING -FUEL FLOW
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ENGINE FUEL INDICATING -FUEL FILTER BYPASS WARNING
General
The fuel filter bypass warning system supplies a discrete signal to the EEC when the fuel filter is about to bypass. The PDS shows a bypass status message in the flight deck.
Fuel Filter Differential Pressure Switch
The fuel pump filter differential pressure switch attaches to the right side of the fuel pump above the filter housing. The switch senses fuel pressure before and after the fuel flows through fuel filter. The switch closes at a differential pressure below the pressure that the filter bypass valve opens.
The differential pressure switch is a LRU.
Functional Description
Before the fuel filter bypass valve opens the fuel pump filter differential pressure switch closes. This sends a discrete signal to the EEC. The EEC sends the signal to the EDIU.
The PDS reads the data and shows a fuel filter bypass message on the status display.
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ENGINE FUEL INDICATING -FUEL FILTER BYPASS WARNING
EFFECTIVITY BEJ ALL 73-30-00
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D633W101-BEJ Jan 05/2003
