B. Detach sensor hot lead at pin 11 of fueling panel disconnect receptacle.
C. Detach sensor ground lead at ground terminal screw.
D. Remove sensor mounting screws and washers and remove sensor from bracket.
E. Check sensor mounting bracket for bent condition or other damage and replace as necessary.
500
Nov 15/79 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-21-81 Page 401
Fueling Power Control Switch Installation 500
28-21-81 Figure 401 May 20/82
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
4. Install Fueling Power Control Switch Sensor (Fig. 401)
A. Install sensor mounting bracket, if removed.
B Locate sensor on inboard side of bracket and install mounting screws and washers.
C. Attach sensor hot lead to pin 11 of fueling panel disconnect receptacle.
D. Attach sensor ground lead to ground terminal screw and tighten screw.
E. Using non-magnetic feeler gage, check gap between actuator magnet and sensor. Gap should be 0.08 +0.02 inch throughout traverse of panel door from closed to open position. If not correct loosen mounting bracket screws and move bracket inboard or outboard parallel to door hinge and retighten screws.
NOTE: If check of sealant attachment of actuator magnet to actuator bracket indicates a faulty attachment of magnet to bracket, re-attach per following paragraph.
5. Repair Fueling Power Control Switch Actuator Assembly
A. Remove old sealant of magnet/bracket attachment and clean faying surfaces with solvent (Ref 20-30-31).
B. Apply one coat of primer to magnet and bracket.
C Apply adhesive to faying surfaces, position magnet on bracket and press gently together. Avoid excessive squeeze-out of adhesive.
D. After adhesive has fully cured, install actuator assembly on stationary half of fueling station door hinge.
E. Check gap between actuator magnet and sensor and readjust as necessary per par. 4.E.
500
Nov 15/79 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-21-81 Page 403
ENGINE FUEL FEED SYSTEM - DESCRIPTION AND OPERATION
1. General
A. The primary function of the fuel feed system is to pump fuel from the fuel tanks to the engines. A minor function is to pump or transmit fuel from tank No. 1 to the APU. The system can be used for transferring fuel from one tank to the other during ground operations only. It is also used for defueling the tanks for ground maintenance.
B. The engine fuel feed system consists of two boost pumps for each tank, one check valve downstream of each boost pump, one boost pump removal valve for each boost pump, a boost pump bypass valve for each main tank, two engine fuel shutoff valves one in the line to each engine, and one fuel crossfeed valve. The boost pump removal valve permits removal of the boost pump without defueling the tank. The boost pump bypass valve allows an engine to continue operation by drawing fuel directly from a tank in the event both boost pumps are not operating. The engine fuel shutoff valves are energized through the fire switches and when closed will result in an engine shutdown.The engine start levers, on the cockpit aisle stand, can be used to open or close the shutoff valves in addition to the fire switches. The fuel crossfeed valve is used to connect the fuel feed system of one wing to the system in the other wing. The fuel crossfeed valve also permits fuel transfer, with airplane on the ground, from one wing tank to the other and permits defueling the entire fuel system through the pressure fueling nozzle.
C. Controls and indicators for the engine fuel feed system are located on the forward overhead panel and consists of a boost pump switch for each boost pump; a low pressure light for each boost pump to indicate operating status of the boost pump; a position indicating light for each fuel shutoff valve; and a fuel crossfeed valve control switch and position indicating light (Fig. 1). The engine fuel shutoff valve is normally open and with the crossfeed valve closed and the boost pumps turned on, the low pressure lights will be off and fuel supplied to the engine fuel control unit.
D. The portion of the fuel feed sytstem used for the APU consists of a fuel shutoff valve and a relief valve. The APU fuel shutoff valve prevents unwanted line drainback or pressurization of the APU system during APU shutdown. A check valve is installed in each of the two branch inlet lines, upstream of the shutoff valve, to prevent backflow in the unpressurized branch.
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