(3) Test Boost Pump Removal Valve, Vent Valve, and Check Valve and Pressure Fueling Line Outlet Check Valve.
(a)
Put suitable container under drain cock of tank No. 1 fwd fuel boost pump (Fig. 501).
(b)
Manually close the fuel boost pump removal valve.
(c)
Open fuel boost pump drain cock. Check for no fuel leakage after residual fuel drains.
(d)
Close circuit breaker on P6 panel for one of the other fuel boost pumps, put that boost pump switch on P5 panel in ON position and pressurize fuel line. Fuel shall not flow from drain cock.
NOTE: If fuel flows from drain cock and the flow increases when the fuel line is pressurized, a malfunction of the fuel boost pump check valve is indicated. If fuel flow does not increase when the fuel line is pressurized, a malfunction of the boost pump removal valve, vent valve or pressure fueling line outlet check valve is indicated.
1) To operate any of the fuel boost pumps, you must be in the flight compartment to continuously monitor the low pressure indication in the fuel tank.
WARNING: DO NOT OPERATE ANY FUEL BOOST PUMP IF THE LOW PRESSURE LIGHT COMES ON AND STAYS ON. FUEL VAPORS IN THE TANK MAY IGNITE AND CAUSE A FIRE OR EXPLOSION.
a) Immediately put the applicable fuel boost pump switch(es) to OFF if the LOW PRESSURE light comes on and stays on.
(e)
Put fuel boost pump switch used to pressurize line, to OFF and open circuit breaker.
(f)
Open the fuel boost pump removal valve. Fuel shall flow from drain cock.
(g)
Close the fuel boost pump drain cock.
(h)
Repeat steps (a) thru (g) for remaining fuel boost pumps.
1) If testing center tank boost pump, manually close both center tank boost pump removal valves. Do not use other center tank boost pump to pressurize system or fuel recirculation through vapor discharge lines will occur and fuel will flow from drain cock. If fuel leaks from both center tank boost pump drain cocks, replace fueling line outlet check valve in center tank.
NOTE: Vent valves are not used in center tank boost pumps.
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(4) Restore Airplane to Normal Configuration
(a)
Place crossfeed valve switch, on P5 panel, in CLOSED position and open MANIF VALVE circuit breaker on P6 panel.
(b)
Install small clearance panels below main tank FWD boost pump removal valve handles. Ensure that retaining chain is not pinched between panel and stringers before tightening screws.
(c)
Remove actuator locks and retract leading edge flaps.
(d)
Install aft main and all center tank fuel boost pump access panels.
NOTE: Insure that boost pump removal valve is open before installing boost pump access panel.
(e)
Remove external electrical power, if no longer needed.
E. Fuel Boost Pump Bypass Valve Test (using fueling truck)
NOTE: This test is applicable for airplanes with bypass valves with valve lock actuating arms only. If airplane bypass valves do not have valve look actuating arms, proceed to par. F.
(1) Prepare for Boost Pump Bypass Valve Test
(a)
Connect external electrical power to airplane (Ref Chapter 24).
(b)
Extend flaps and install leading edge flap locks (Ref 27-81-0 MP).
WARNING: REFER TO 27-81-0 MP FOR LOCK INSTALLATION PROCEDURE. FLAPS ARE FAST ACTING AND CAN CAUSE SERIOUS INJURY TO PERSONNEL.
(c)
Remove small clearance panels from wing lower skin, below main tank FWD boost pump removal valve handles (Fig. 501, View 4).
CAUTION: CLEARANCE PANEL MUST BE REMOVED OR DAMAGE TO REMOVAL VALVE WARNING SIGNAL MAY RESULT WHEN VALVE CLOSING IS ATTEMPTED.
(d)
Gain access to AFT main and all center tank boost pumps,by removing access panels No. 7201L, 7203L, 7401R and 7403R.
(e)
Pull engine fire switches on aisle stand aft electronic panel (P8) to FIRE position to close engine fuel shutoff valves.
(f)
Open manual defueling valve.
(g)
Open pressure fueling control station door. Remove cap from pressure fueling receptacle, and connect hose from fueling truck.
NOTE: It is good practice to use a 200-mesh screen in the hose fueling adapter during test.
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(h)
Check that each fuel tank contains at least 150 gallons of fuel.
(i)
Remove applicable fuel boost pump bypass valve access plugs in wing lower surface.
