(e)
If the No. 2 or 3 crossfeed valve remains closed with the flaps not extended for takeoff (0-7.5, 22.5-30 units) the EICAS advisory message >X FEED CONFIG will show.
(10)
Fuel remaining in the center wing tank, which cannot be pumped out by the override/jettison pumps, is removed with the scavenge system. For information on the center wing tank scavenge system, refer to 28-15-00/001.
(11)
When the center wing tank is emptied or both center wing tank override/jettison pumps are off, the FSMC provides a ground for the inboard main tank override/jettison pump control relays, enabling power to be supplied to the pumps. The pumps operate the same as the center wing tank override/jettison pumps, overriding the fuel supplied by the main tank boost pumps. Symbols on the EICAS fuel synoptic illuminate to indicate that pumps are operating.
(a)
If the pump output pressure does not increase to the normal operating range when the pump is turned on, the PRESS light on the pump control switch illuminates, a FUEL OVRD 2 or FUEL OVRD 3 advisory message is displayed on the EICAS main screen, and a status message is recorded.
(12)
As fuel is removed from the inboard main tanks, the FSMC monitors inputs from the fuel quantity processor and the single point sensors. When fuel quantity in either inboard main tank decreases below 6,000 gallons, the FSMC opens transfer valves to transfer fuel from the reserve tanks into the inboard main tanks. For more information on the reserve tank fuel transfer system, refer to 28-16-00/001.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400
MAINTENANCE MANUAL
(13)
When the fuel quantity in the inboard and outboard main tanks become even, the EICAS displays the FUEL TANK/ENG (advisory) message. The pilot's action when the EICAS message shows is to close the No. 1 and No. 4 crossfeed valves. This begins the tank to engine fuel-feed segment of the flight.
(14)
The EICAS message > X FEED CONFIG (ADVISORY) message shows to advise the flight crew that one or more of the crossfeed valves is in the incorrect position for the configuration of the airplane. The pilot's action when the EICAS message shows is to open or close the applicable crossfeed valve(s) to put the fuel system in the correct engine fuel-feed configuration.
(a)
The > X FEED CONFIG (ADVISORY) message shows when: 1) The No. 2 and/or No. 3 crossfeed valve(s) are closed with the flaps in the retracted position or,
2) The No. 2 and 3 crossfeed valves are not automatically commanded to the closed position (takeoff command) with the flaps set for takeoff and the airplane in ground mode or,
3) The No. 1 and/or No. 4 crossfeed valve(s) are closed and the airplane is not in the tank to engine fuel-feed configuration (inboard and outboard main tanks equal).
(15)
To determine when the No. 1 and 4 crossfeed valves should be opened or closed, the > X FEED CONFIG and FUEL TANK/ENG messages use the FQIS MAIN TANKS EQUAL input (also referred to as the TANK TO ENGINE ALERT discrete) to determine when the main tank fuel quantities are equal.
(a)
The TANK TO ENGINE ALERT discrete is set when:
1) The fuel quantity in the No. 2 main tank equals or is less than the fuel quantity in the No. 1 main tank, or the fuel quantity in the No. 3 main tank equals or is less than the fuel quantity in the No. 4 main tank or,
2) The fuel quantity in the No. 2 main tank is not more than 1000 pounds (454 kilograms) more than the No. 1 main tank fuel quantity, and the fuel quantity in the No. 3 main tank is not more than 1000 pounds (454 kilograms) more than the No. 4 main tank quantity and one of these conditions is true: a) The fuel quantity processor unit is powered up. b) The CMCS ground test, <FUEL QUANTITY IND is completed. c) The refuel control panel is closed after it has been
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