(a)
6H23, L FWD FUEL BOOST PUMP

 S 214-018
 (16)
 Make sure the APU fire switch on the pilots aft control stand, P8, is in the NORMAL position.

 S 864-019

 (17)
 Put the APU master control switch on the overhead panel, P5, to the ON position.

 S 214-020

 (18)
 Make sure the manual override handle on the actuator moves to the OPEN position.

 S 864-021

 (19)
 Put the APU master control switch on the P5 panel to the OFF position.

 S 864-031

 (20)
 Remove the DO-NOT-CLOSE tag and close this circuit breaker on the P6 panel:

 (a)
6H23, L FWD FUEL BOOST PUMP

 (21)
 Remove electrical power if it is not necessary (AMM 24-22-00/201).

 S 864-022
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 28-25-11
 ALL  ú ú 01 Page 405 ú Sep 28/00

A

757 MAINTENANCE MANUAL
 DEFUELING - DESCRIPTION AND OPERATION
_____________________________________
 1.  General (Fig. 1)_______
 A.  The defueling system consists mainly of defueling valves. Other necessary components include the boost pumps, The boost pump bypass valves, the fueling valves, and the crossfeed valve (AMM 28-22-00/001). Three methods for defueling a fuel tank include pressure defueling, suction defueling, and tank-to-tank transfer.
 B.  Defueling
 (1)  
The defueling system consists of a defueling valve at the left and right ends of the center fuel tank connecting the fuel feed manifold to the main fueling manifold. Fuel extraction takes place at the fueling station through fueling adapters (AMM 28-21-00/001).

 (2)  
Pressure defueling and suction defueling provide the means for defueling the fuel tanks. A boost pump bypass suction line connects each main fuel tank to the fuel feed manifold. Suction defueling draws fuel into the boost pump bypass through the fuel feed manifold and main fueling manifold and out of the fueling adapters. Only the main fuel tanks may be suction defueled. Pressure defueling uses the boost pumps to pump the fuel out of the tanks through the same fuel path.

 (3)  
Only on-ground defueling is possible. Airborne fuel jettisoning is not possible. Fueling station controls regulate defueling.

 C.  
Tank-To-Tank Fuel Transfer

 (1)  
Defueling of a fuel tank by transferring the fuel to the other fuel tank requires use of defueling valves, fueling valves, the crossfeed valve, and the boost pumps (AMM 28-22-00/001).
　
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本文鏈接地址：757 AMM 飛機(jī)維護(hù)手冊 燃油 CHAPTER 28 - FUEL 4(59)