747-400 AMM 飞机维护手册 燃油 FUEL 2(65)

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 13. Fuel Crossfeed Valve (Fig. 1)
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 A.  Four fuel crossfeed valves provide a means of directing fuel flow in the fuel manifold. The valves are the same as the engine fuel shutoff valves except for length of the adapter shafts. The valves are located in the fuel feed manifold with the valve actuators installed on the front spar.
 B.  The valves are controlled by individual fuel crossfeed valve switches on the fuel management control module. Valves for No. 2 and No. 3 main tanks are controlled automatically during take-off by the fuel management system.
 C.  Valve operation may be verified by monitoring the manual position lever on the valve actuator or the crossfeed valve symbols on the fuel synoptic.
 14. Fuel Crossfeed Valve Control Switch (Fig. 2)
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 A.  Four fuel crossfeed valve control switches supply 28-volt dc power to the crossfeed valves. The switches are located on the fuel management control module on the P5 pilots' overhead panel.
 B.  When the switch is operated, a white flowbar is illuminated on the switch to indicate that the valve has been commanded open. If actual crossfeed valve position disagrees with the selected valve position, the word VALVE is illuminated on the switch. The switch lights are powered by the master dim-and-test circuit.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL

 C.  When the No. 2 or 3 crossfeed valve is manually pushed to the on (valve open) position, the white flow bar in the switch will show. If the crossfeed close command is active, the No. 2 and 3 crossfeed valves are commanded closed by the FSMC cards. In this condition (valve commanded closed, switch on) the white flow bar will still display in crossfeed valve switch.
 15. Fuel System Card File (Fig. 4)
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 A.  The fuel system card file contains the printed circuit cards required to operate the fuel management system, monitor the system components, and interface with the EICAS and CMCS through the ARINC 429 digital data bus.
 B.  The card file is located in the left crawlway next to the nose wheelwell.
 C.  The card file contains 16 double-width slots to accommodate the fuel system control cards [fuel system management card (FSMC), valve position logic card (VPLC), fuel jettison control card (FJCC), and fuel system/EICAS interface card (FSEIC)] and 4 single-width slots for the single point sensor (SPS) cards. The file contains 8 receptacles to interface with airplane wiring. A system access panel, located to the right of the wiring receptacles, allows the monitoring of the digital transmission between the FSEIC and FSMC, and EICAS.
 16. Fuel System Management Card (FSMC)
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 A.  The fuel system management cards (FSMC), in conjuction with the fuel management control module in the flight compartment, control the flow of fuel from the fuel tanks to the engines. The cards control the operation of the fuel system pumps and valves in accordance with the fuel feed schedule, while maintaining the airplane within its lateral balance and center-of-gravity limits.
 B.  Each FSMC is a single-board printed circuit assembly installed in a slot in the fuel system card file. The card is retained in the card file by two lever locks and two captive screws that thread into holes in the card file. The card is easily replaced - no special tools are required. Two identical cards are installed so that the fuel feed system remains operational in the event of a single card failure. The cards are located in the fuel system card file at file positions 5 and 10.
 C.  The FSMC receives inputs from the fuel management control module, the valve position logic cards, the fuel quantity processor unit, the flap control unit (FCU), the ground safety relay system, and fuel single point sensor cards. These inputs are processed by the card, which then turns fuel pumps on or off and opens and closes valves to deliver fuel from the appropriate tank(s) to the engines. The card also receives inputs from the fuel system/EICAS interface card (FSEIC) to perform BITE. In the event that a fuel system component does not operate as commanded by the FSMC or fuel management control module, the FSMC will annunciate the discrepancy to the FSEIC via the ARINC 429 data bus. The discrepancy will be apparent as an advisory or status message on EICAS.
　
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