F94755
Engine Fuel Feed System Component Location  5C8 
28-22-0  Figure 1 (Sheet 1)  Aug 01/96 
Page 2 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

5C8  Engine Fuel Feed System Component Location 
Aug 01/96  Figure 1 (Sheet 2)  28-22-0 
Page 3 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

G43281F94824
Engine Fuel Feed System Component Location  509 
28-22-0  Figure 1 (Sheet 3)  Feb 20/89 
Page 4 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

5C8  Engine Fuel Feed System Component Location 
Aug 01/96  Figure 1 (Sheet 4)  28-22-0 
Page 4A/4B 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

2.  Engine Fuel Shutoff Valve
A.  Two engine fuel shutoff valves mounted on the wing front spar provide the means of shutting off the fuel supply to the engines. The valve for engine No. 1 is in the left wing, and the valve for engine No. 2 is in the right wing. Each valve is an electric motor-driven slide shutoff valve with a manual override handle. The manual override handle provides a visual check of the valve position and a manual method of positioning the valve when the electric motor is not energized. To limit the pressure buildup in the fuel lines, the valve housing incorporates a thermal relief valve (Fig. 2).
B.  The valves are operated by 28-volt dc power and are controlled by the fire switches on the aft electronics panel. The valves are also controlled by mechanically operated switches actuated by the engine start levers on the cockpit aisle stand. The valves are energized to close whenever the start levers are in cutoff position. Position lights on the overhead panel are illuminated any time the valve motors are energized.
3.  Fuel Boost Pump
A.  The fuel boost pumps deliver fuel under pressure from a tank to its respective engine or through the crossfeed valve to the other engine. Each pump is a centrifugal type pump driven by an ac motor controlled by a separate switch on the overhead panel. Each pump is isolated from the fuel tank by being installed in a pump housing within a tank or on the forward side of the front spar.
B.  Fuel enters the pump through a wire mesh screen at the suction tube inlet then flows through a manually operated pump removal valve. The pump removal valve allows removal of a pump without draining the tank. A portion of the fuel being pumped is circulated through the pump to act as a lubricant for the bearings and a coolant for the motor. Fuel is discharged from the pump through the boost pump check valve. A small vent valve vents the pump casing to the fuel tank. Access to the vent valve is gained by defueling, purging and entering the applicable fuel tank.
4.  Fuel Boost Pump Removal Valve
A.  The fuel boost pump removal valve permits removing the fuel boost pump without defueling the tank. The valves are manually operated slide shutoff valves and are located in the inlet line to each fuel boost pump. The valve control shaft passes through the wall of the boost pump housing so that the valve may be operated from the outside of the fuel tank.
540 
Oct 20/86  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  28-22-0 Page 5 

5 Fuel Boost Pump Check Valve
A.  The fuel boost pump check valve closes the boost pump outlet line when the pressure drops below a predetermined amount, thus preventing reverse fuel flow to the boost pump. Main tank boost pump check valves differ from center tank boost pump check valves as the cracking pressure for main tank boost pump check valves is approximately 12 psi and cracking pressure for center wing tank boost check valves is approximately 1.3 psi. The valve consists of a spring-loaded-closed flapper valve mounted in a housing. The housing has three ports: fuel in, fuel out and a pressure sensing port. The pressure sensing port is located upstream of the flapper valve and is connected to the boost pump low pressure switch. Refer to fuel feed low pressure indicating system, 28-42-0. The valves are located inside the fuel tank on the wall of the boost pump housing. (See figure 1.) Access to the valves is gained by defueling, purging and entering the applicable fuel tank.

Engine Fuel Shutoff Valve  514 
28-22-0  Figure 2  May 15/73 
Page 6 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 
　
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