B. The actuator has a dc electric motor, gear train, limit switches, and a manual override lever, which also serves as a position indicator for the valve. The actuator is readily replaceable without disturbing the fuel seals for the valve and without defueling the tank.
C. The valve has a housing, a butterfly-type valve disk and provisions for connecting manifold tubing to the valve. The valve is installed and sealed on the wet side of the spar and is only accessible by defueling and entering the fuel tank.
D. Fuel jettison transfer valves are operated automatically by the fuel jettison control card. During fuel jettison operation, the fuel jettison transfer valve control relay is energized by the fuel jettison control card, causing the valve to open. The VALVE OPEN circuit on the FSEIC is energized by the valve position logic card card, causing the fuel system synoptic on EICAS to show that valve is open. If the valve position does not agree with the command from the fuel jettison control card, a valve disagreement status message is recorded and shown on the auxiliary EICAS screen when the STAT button is pushed.
E. Jettison transfer valve operation is tested by initiating applicable CMCS BITE from any CDU.
11. Fuel Jettison Control Card
__________________________
A. The fuel jettison control card (FJCC) controls the operation of the fuel jettison system. It supplies or removes grounds for valve and pump control relays, based on signals from the fuel quantity processor unit and the fuel jettison single point sensor control card. The FJCC interacts with EICAS to show the fuel quantity to remain and alert and status messages. The FJCC also interacts with the CMCS to do the BITE on the card on command and during power-up.
B. Fuel jettison control cards are printed circuit cards installed in the fuel system card file in the main equipment bay. FJCC A is installed at position 7 and FJCC B is installed at position 8.
C. The fuel system card file access panel test points are used for accessing the ARINC data bus and for activating the power-up ground bite tests for the cards. The points HI, LO, and SHIELD are outputs for the ARINC data bus analyzer. The points FSMC A, FSMC B, FJCC A, FJCC B, and FSEIC are bite inputs to the cards. Grounding the test points activates the power-up ground bite test for the cards.
12. Operation
_________
A. Functional Description (Fig. 2 and 3)
(1)
The fuel jettison system becomes operative when the fuel jettison control card is activated by putting the fuel jettison control selector switch to A or B position.
(2)
When the system is activated, TO REMAIN fuel quantity shows in magenta on the main EICAS screen (Fig. 4). Time necessary to jettison is shown on the auxiliary EICAS screen when the fuel synoptic is selected. TO REMAIN quantity can be adjusted with the FUEL TO REMAIN knob on the jettison module. The minimum TO REMAIN value that may be selected is 28,000 pounds (12,700 kilograms), leaving 7000 pounds (3175 kilograms) of fuel in each main tank.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-31-00
ALL ú ú 01 Page 8 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
TO EICAS (SYNOPTIC)
TO EICAS (MESSAGE)
FUEL JETTISON NOZZLE VALVE
1 STATUS MESSAGE
ADVISORY MESSAGE
Fuel Jettison System Simplified Schematic
Figure 2 (Sheet 1)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-31-00
ALL ú ú 01 Page 9 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
FUEL JETTISON TRANSFER VALVE
STATUS MESSAGE
Fuel Jettison System Simpified Schematic
Figure 2 (Sheet 2)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-31-00
ALL ú ú 01 Page 10 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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