28-21-00
ALL ú ú 01 Page 5 ú May 20/98
A
757
MAINTENANCE MANUAL
(b) Actuator of the Fueling Shutoff Valve
1) When fuel under pressure enters the valve inlet, with the
fueling shutoff valve closed, fuel flows through a passage
to the solenoid side of the diaphragm. A passage through
the shaft connects cavities on the two sides of the
diaphragm. Actuating the solenoid controlled pilot valve,
opens a larger outlet passage on the tank side of the
diaphragm. The difference in fuel pressure moves the
diaphragm in a direction that forces the poppet open.
2) To close the fueling shutoff valve with pressure in the
fueling manifold, de-energize the solenoid valve. With the
flow stopped, pressures equalize on the two sides of the
diaphragm, and permit the spring loaded poppet to close.
Spring pressure holds the poppet closed with pressure
removed from the fueling manifold.
3) The valve position switch supplies the fueling station with
an indication of the fueling shutoff valve position.
(c) Manual Operation
CAUTION: MAKE SURE THERE IS NO PRESSURE IN THE FUELING_______
MAINFOLD BEFORE YOU TURN THE MANUAL OVERRIDE KNOB.
DAMAGE TO THE VALVE OR THE MANIFOLD CAN OCCUR.
1) The fueling shutoff valve opens or closes manually if you
turn the manual override knob 10 to 13 complete
revolutions. Clockwise rotation closes the fueling shutoff
valve. Counterclockwise movement opens it. A lockwire
holds the manual override knob in the closed position.
NOTE: The attach screws that attach the coverplate____
over the manual override knob should not be tampered
with. Tampering with the attach screws on the
coverplate could cause fuel leaks.
D. Fueling Adapters (Fig. 4)
(1) Description
(a) Two fueling adapters attach to the front spar of the right wing
at the fueling station. The fueling adapters permit pressure
fueling and defueling of the airplane fuel tanks. The fueling
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本文鏈接地址：757 AMM 飛機維護手冊 燃油 CHAPTER 28 - FUEL 2(40)
