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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 214-159
 (2)  Do a visual inspection of the wire terminal assembly (Fig. 402, View A):
 NOTE: These steps are necessary for boost pumps that have been
____ previously installed. It it not necessary to do the visual inspection for new pumps.
 (a)  Look for these conditions: 1) Indication that fuel has leaked from the wire terminal assembly.
 2)  Indication that the terminal assembly or wire insulation is discolored because of too much heat. a) Clean the wire bundle caps per SWPM 20-60-01.
 3)  Indication of damage to the wire terminal assembly, for example: a) bulges b) bent flanges c) broken screws d) medium to heavy corrosion damage (reference the 747
 Corrosion Prevention Manual, CPM 20-40-00, Part I, General Information - Corrosion Removal Techniques, Paragraph 3.A).
 S 214-160
 (3)  
If the visual check shows that the fuel pump is OK, do this
 procedure: Fuel Pump Continuity Check.

 S 214-161

 (4)  
If the visual check shows that the fuel pump is not OK, do these steps:

 (a)  
Replace the boost pump motor/impeller unit.

 (b)  
Do the continuity/resistance checks for the replacement fuel pump. 1) Start with this procedure: Fuel Pump Continuity Check.

 G.  
Fuel Pump Continuity Check

 S 014-162
 (1)  Disconnect the electrical connector from the pump motor/impeller unit.
 S 864-163
 WARNING: MAKE SURE THE METER USED TO MEASURE THE BONDING JUMPER
_______ CONTINUITY IS RESISTANT TO EXPLOSION. IF NOT, IT IS POSSIBLE THAT AN EXPLOSION OR FIRE CAN OCCUR.
 (2) Use the AVTRON Model T477W bonding meter (SWPM 20-20-00, para I).
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 28-22-03
 ALL  ú ú 02 Page 417 ú Feb 18/00
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A
747-400
MAINTENANCE MANUAL

 S 764-164
 (3)  Measure the resistance between pin 4 of the electrical connector and the braided bonding jumper on the fuel pump (Fig. 402, View B).
 NOTE: The measurement between pin 4 and the bonding jumper is a
____ continuity check, not a bonding resistance check.
 S 974-165
 (4)  
Record the resistance measured between pin 4 and the braided bonding jumper on the data sheet (Fig. 403).

 S 764-166

 (5)  
If the resistance is less than or equal to 1.99 ohms, do this procedure: Initial Insulation Resistance Check.

 S 764-167

 (6)  
If the resistance is more than 1.99 ohms, do these steps:

 (a)  
Replace the boost pump motor/impeller unit.

 (b)  
Do the continuity/resistance checks for the replacement fuel pump. 1) Start with this procedure: Fuel Pump Continuity Check.

 H.
Initial Insulation Resistance Check

 S 764-168
 CAUTION:_______DO THE RESISTANCE CHECK AT 10 VDC FIRST. THE FUEL PUMPS ARE IN FLAMMABLE LEAKAGE ZONES. EACH PUMP IS TESTED AT 10 VDC BEFORE IT IS TESTED AT 500 VDC. THE INITIAL 10 VDC CHECK IS TO FIND OUT IF A FUEL PUMP HAS LOW INSULATION RESISTANCE WHICH CAN ARC OR OVERHEAT WHEN A HIGH VOLTAGE IS APPLIED. THE RESULTS OF THE 10 VDC CHECK WILL TELL YOU IF IT IS SAFE TO DO THE 500 VDC DO A CHECK WITH THE FUEL PUMP INSTALLED ON THE AIRPLANE.
 (1)  Do these steps to check the insulation resistance (initial check):
 NOTE: These steps are done at 10 VDC to prevent arcing or
____ overheat in a flammable leakage zone when high voltage is applied to a pump with low insulation resistance.
 (a)  
Do this procedure: Calibrate the QuadTech Model 1864 megohmmeter.

 (b)  
Disconnect the electrical connector from the pump motor/impeller unit.

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