(d)
The adapter/shaft connects the actuator and the valve body. The adapter/shaft consists of an adapter plate and a shaft with a universal joint. The adapter/shaft, with indexed splines in both ends, ensures correct alignment of the actuator to the valve. Access to the adapter/shaft requires defueling.
(e)
The thermal relief valve(s) on the valve body, crack and reseat between 70 to 55 psig.
(2)
Function
(a)
Applying 28VDC power opens or closes the valve, depending upon the command. Upon reaching open position, the butterfly plate contacts a stop pin to prevent over-travel. With the valve full OPEN, the open limit switch actuates de-energizing the actuator. Upon reaching the full closed position, the butterfly plate contacts a stop pin which prevents over-travel. With the valve full CLOSED, the closed limit switch closes de-energizing the actuator.
(b)
The defueling valve position determines whether the main fueling manifold is connected to the fuel feed manifold.
3. Operation (Fig. 3)
_________
A. Functional Description
(1)
Defueling
(a)
Pressure Defueling
1) For pressure defueling the fuel system must be configured as follows: a) At least one boost pump for the tank being defueled
must be on (AMM 28-22-00/001). b) At least one defueling valve must be open. c) The fueling adapters must be placed in the defuel mode
before connecting the fueling nozzles (AMM 28-21-00/001).
(2)
Suction Defueling
(a)
Suction defueling requires a configuration of the fuel system similar to pressure defueling except that the boost pumps for the tank being defueled must be off.
(b)
Only the main fuel tanks may be suction defueled.
(3)
Tank-To-Tank Fuel Transfer
(a)
For transfer of fuel between tanks the fuel system must be configured as follows: 1) At least one supplier tank boost pump must be operating. 2) The LH or RH defueling valve must be open as applicable.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-26-00
ALL ú ú 03 Page 4 ú May 28/99
A
757
MAINTENANCE MANUAL
FUELING PANEL
Defueling Schematic
Figure 3 (Sheet 1)
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. AIRPLANES WITH A ROUND (ALTERNATE) ú 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 燃油 CHAPTER 28 - FUEL 4(61)
