BACKGROUND

This inspection will make sure the 747 fuel pumps

will not cause a fuel leak.Operators have sent reports of fuel leaks at the fuel boost and override/jetison pumps.
The reports tell that eight fuel pumpe have been removed for this reason. The removed fuel pumps had between
34.000-67 ,000 hours since new or since overhaul. The leaks occurred at the pump/wire bundle interface.
The result of one leak was a fire at an inboard main tank jettison pump during maintenance.

C. Special Tools and Equipment

1. A special megohmmeter is necessary to do the electrical check of the fuel pump on the airplane.

The megohmmeter must have 10VDC and 500VDC voltage supply options with a maximum short

circuit current of 5 milliamperes. We use a QuadTech model 1864 megohmmeter. Any equivalent

meter is acceptable. The QuadTech model 1864 Is available from:

COMPLIANCE

Boeing recommends that the initial inspection be accomplished at the next opportunity when

manpower and facilities are available. For pumps with insulation resistance between

1and5 megohms when the 500VDC is done, it is recommended that the pump be replaced. If the

pump is not replaced, do the inspection of this pump at every A-check or an equivalent time.
For pumps with insulation resistance greater than 5 megohms

when the 500VDC is done, the inspection should be repeated at every
C-check or an equal time period after the initial inspection.

CAUTION:

The fuolpumpe are in. flammahie, leakage zones. Each pump is tested at 10 VDC before it is tested at 500 VDC.
The 10 VDC test is to find fuel pumps with low insulaton resistance that can arc or overneat when a high voltage ls
aplled. the results of the 10 VDC test determine if the 500 VDC test is done on a fuel pump installed on the airplane.