28-22-00
 ú ú 05 Page 20 ú Jan 20/99

C24165
A
757
MAINTENANCE MANUAL

 (2)  
Boost pump switchlights, on the pilot's overhead panel P5, control each boost pump through a control relay. Pressing the appropriate PUMP switchlight to ON energizes the corresponding control relay. The boost pump then receives 115 vac electrical power and begins to operate. The boost pump draws fuel from its fuel tank and pressure feeds the engine on the same side of the airplane unless the crossfeed valve is open. Each operating boost pump provides fuel flow through the motive port of the automatic sumping jet pump. Fuel flow through the motive port draws in fuel from the scavenge area and discharges it at the boost pump inlet.

 (3)  
Placing the engine fuel control switch, on the quadrant stand (P10), in the RICH or RUN position opens the corresponding engine fuel shutoff valve. A SPAR VALVE disagreement light on the P10 panel provides indication of valve transition and failure. An EICAS level C advisory message L/R FUEL SPAR VALVE also provides indication of valve failure. The SPAR VALVE light remains on until the valve position agrees with its commanded position or until the valve fault disappears.

 (4)  
Opening the engine fuel crossfeed valve(s) lets any fuel tank supply fuel to either engine. The crossfeed valve switchlight(s), on the overhead panel, P5, controls the crossfeed valve(s). Pushing the switchlight(s) to the open position commands the crossfeed valve(s) to open. A VALVE disagreement light on the P5 panel supplies indication of valve transition and failure. An EICAS level C advisory message FUEL CROSSFEED or FWD/AFT FUEL CROSSFEED also supplies indication of valve failure. The VALVE light stays on until the valve position agrees with its commanded position or until the valve fault does not show. For airplanes with FWD and AFT crossfeed valves the EICAS message XFEED IND can show if there is a interface failure with the EICAS computers.

 (5)  
A boost pump bypass valve in each main fuel tank allows suction fuel feed to each engine if normal fuel feed is inhibited.

 (6)  
The left forward fuel boost pump is also used for the APU fuel feed (AMM 28-25-00/001).

 B.
Control

_______
 (1)  
Make sure these circuit breakers are closed:

 P6 Panel________ P11 Panel R SPAR FUEL VALVE R DISAGREE ENBL L SPAR FUEL VALVE L DISAGREE ENBL LEFT FORWARD FUEL BOOST PUMP FUEL CROSSFEED (OR) LEFT AFT FUEL BOOST PUMP FWD FUEL CROSSFEED RIGHT AFT FUEL BOOST PUMP AFT FUEL CROSSFEED RIGHT FORWARD FUEL BOOST PUMP XFEED IND R FUEL OVRD BOOST PUMP L FUEL OVRD BOOST PUMP

 (2)  
Provide electrical power (AMM 24-22-00/201).

 (3)  
Place engine fuel control switch in RUN position (P10).

 (4)  
Press applicable BOOST PUMP switchlight on P5 panel to ON. Check the ON flow bar comes on.
　
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本文鏈接地址：757 AMM 飛機維護手冊 燃油 CHAPTER 28 - FUEL 2(103)