(1)
Description
(a)
The APU fuel shutoff valve is a motor actuated ball valve. The shutoff valve mounts to the rear spar of the center wing fuel tank. The valve body (inside the fuel tank) attaches to the actuator (outside the fuel tank) so that defueling is not required for actuator removal. A thermal relief, ported to the tank side of the valve, cracks and reseats between 75 and 45 psig. A slotted ball within the valve body controls fuel flow through the valve.
(b)
The square (preferred) actuator of the APU fuel shutoff valve has a 28v dc permanent magnet motor, an electrical connector, OPEN - CLOSED limit switches, and a manual override handle. The manual override handle also shows the position of the APU fuel shutoff valve.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-25-00
ALL ú ú 01 Page 4 ú Sep 20/98
A
757
MAINTENANCE MANUAL
ELECTRICAL CONNECTOR
REAR SPAR (DRY SIDE)
REAR SPAR (WET SIDE)
APU FUEL FUEL LINE
SHUTOFF VALVE
SEE A
VALVE BODY ACTUATOR
MANUAL OVERIDE HANDLE
APU FUEL SHUTOFF VALVE A1
ELECTRICAL
CONNECTOR
REAR SPAR
(DRY SIDE)
REAR SPAR
(WET SIDE)
ACTUATOR
FUEL LINE
VALVE BODY
MANUAL OVERIDE HANDLE
APU FUEL SHUTOFF VALVE A2
1 PREFERRED
2 ALTERNATE
APU Shutoff Valve
Figure 3
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-25-00
ALL ú ú 01 Page 5 ú Sep 20/98
A
757
MAINTENANCE MANUAL
(c)
The round (alternate) actuator consists of a 28vdc drive motor, an electrical connector, open-closed limit switches, and a manual override handle which also functions as a position indicator.
(2)
Function
(a)
Applying 28vdc power opens or closes the valve, depending upon the command. The actuator shaft engages the body shaft which inserts into the ball slot. During an open command the actuator shaft rotates turning the ball within the valve body to allow fuel to flow through the ball. Upon reaching the full open position, the actuator open limit switch actuates to shut off the actuator. During a close command the actuator shaft rotates, thus turning the ball to prevent fuel flow through the ball. Upon reaching the full closed position, the actuator closed limit switch actuates to shut off the actuator.
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：757 AMM 飛機維護手冊 燃油 CHAPTER 28 - FUEL 4(8)
