(21)
When the pump low pressure indicating light goes off, put the boost pump switch to OFF position.
(22)
Repeat steps (15) through (21) for the L CTR tank fuel boost pump.
(23)
Push in the engine fire switches.
(24)
Determine if there is further need for electrical power on airplane; if not, remove electrical power.
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28-42-0 Page 502 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. May 01/03
2. Fuel Boost Pump Output Pressure Test
NOTE: This test is not necessary if SB 28A1114, Part II is completed.
A. General
(1)
This procedure does a check of the output pressure of each boost pump in the No. 1 and No. 2 fuel tanks. The output pressure is measured at the fuel filter drain of one of the engines. If a pump does not supply a minimum output pressure, a problem may exist.
(2)
This inspection has two alternatives. In alternative 1, you measure the output pressure of the pumps at one of the engines. Alternative 2 lets you measure the pressure for each pump at its low pressure switch. Alternative 2 may be easier if you want to replace the low pressure switches (AMM 28-42-11/401) at the same time that you do this inspection. It is only necessary to do one of the two alternatives.
(3)
This inspection is NOT applicable to airplanes (737-100 and 737-200) having only TRW fuel boost pumps for the two main fuel tanks. This test is optional for the TRW pumps.
B. Equipment
(1)
Gage-Fuel Pressure
(a)
Range 0-50 psig
(b)
Accurate to +/- 1 psig
(2)
Hose
(a) Bleed valve and fitting with 05625-18UNF thread
(3)
Container
(a) Five gallon or larger capacity
(4)
Ground Power Availability
C. References
(1)
Fuel Boost Pump (AMM 28-22-41/401)
(2)
Power Plant (AMM 71-00/201)
(3)
Fuel Filter Cartridge (Ref Pratt & Whitney Engine Manufacturing Maintenance Manual)
D. Test Preparation (Alternative 1)
(1)
Set the APU in the off position.
(2)
No. 1 and No. 2 fuel tanks must have a minimum of 2,000 pounds (900 kilograms) of fuel in each tank.
(3)
Set engine start switches and levers in the OFF position.
(4)
Set all six FUEL PUMP switches in the OFF position.
NOTE: Although only four fuel boost for the main fuel tanks will be tested, all six fuel pump switches must be set in the OFF position. If they are not all off, pressurized fuel may come out when the fuel filter plug is removed. Also, if a center boost pump is on during the test, pressure indications will be inaccurate.
(5)
Make sure the engine start levers are in the CUTOFF position.
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May 01/03 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-42-0 Page 503
E. Test Procedure (Alternative 1)
(1)
Open the right removable fan cowl on the No. 1 and No. 2 engine (All four pumps can be tested from one engine).
(2)
Put a five gallon container below the fuel pump on the engine.
(3)
Remove the plug from the fuel purge port at the bottom of the fuel pump (Fig. 501) and discard the O-ring.
NOTE: Fuel will drain from the opening. Make sure the pressure gage hose fitting is prepared for installation to minimize fuel leakage.
(4)
Attach the pressure gage hose fitting (Fig. 502) to the fuel purge port.
NOTE: Use a 0.5625-18UNJF or 0.5625-18UNF fitting.
(5)
Open the airplane fuel crossfeed valve.
(6)
Move the engine start lever for the engine with pressure gage attached to the RUN position.
(7)
Do the following steps for each of the fuel boost pumps in the No. 1 tank and the No. 2 tank (test not necessary for center fuel tank):
(a)
Make sure only one boost pump is turned on each time these steps are done.
NOTE: Do not try to test more than one boost pump at a time.
(b)
Open the bleed valve on the pressure gage hose until fuel comes out of the drain hose and the pressure becomes stable.
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