G. Fuel quantity indicators, on pilots’ center instrument panel and pressure fueling station, indicate the quantity of fuel on the airplane. Measuring sticks (drip sticks), installed on the underside of each tank, can also be used to determine fuel quantity. For information of the fuel quantity indicating system, refer to 28-41-0 and 28-41-05.
H. Fuel feed low pressure indicating lights, on the forward overhead panel, indicate low engine boost pump outlet pressure. For information on the low pressure indicating system, refer to 28-42-0.
I. A fuel temperature indicator, on the forward overhead panel, indicates fuel temperature in tank No. 1. For information on the fuel temperature indicating system, refer to 28-43-0.
J. Fuel is delivered to the APU from tank No. 1 either through an independent fuel inlet or through a connection to the engine fuel feed system. The engine ac boost pumps can be used to pressurize the APU fuel feed system. A check valve in each inlet line prevents reverse flow through the inactive inlet line. An electrically-operated shutoff valve, downstream from the inlet tee, prevents pressurization of the APU fuel line during APU shutdown. For information on the APU fuel feed system, refer to 28-22-0. For information on the APU, refer to Chapter 49, Airborne Auxiliary Power.
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FUEL -MAINTENANCE PRACTICES
1. General
A. This procedure has tasks for inspection and replacement of the electrical bonding jumpers in the fuel system.
2. Inspection of the Electrical Bonding Jumpers in the Fuel System
A. General
(1)
This task contains visual, mechanical and physical inspections of the electrical bonding jumpers in the fuel system.
(2)
The tin plating on the bonding jumper usually supplies a smooth finish. When there is deterioration of the tin plating on the bonding jumper and the copper in the wire reacts with any sulfur compounds in the tank, the finish becomes rough to the touch and the bonding jumper can show signs of fraying.
B. References
(1) SWPM 20-20-00, Electrical Bonds and Grounds
C. Electrical Bonding Jumper Visual Inspection
(1) Visually inspect the bonding jumper color.
(a)
If the bonding jumper is silver in color and does not show a color change, then the bonding jumper is satisfactory.
(b)
If the wire braid on the bonding jumper has black or brown deposits, do the task: Electrical Bonding Jumpers in the Fuel System Replacement.
(c)
If only the areas near the lugs have black or brown deposits, do the "Electrical Bonding Jumpers Physical Inspection" procedure.
D. Electrical Bonding Jumper Mechanical Inspection
(1)
Try to turn the bonding jumper lugs and tube clamps, if applicable, with light finger pressure.
(2)
If the bonding jumper is loose, rework the electrical bond path (SWPM 20-20-00).
E. Electrical Bonding Jumper Physical Inspection
(1) Feel along the length of the bonding jumper and visually inspect the bonding jumper to find deterioration.
CAUTION: DO NOT FLEX, BEND OR KINK THE BONDING JUMPERS MORE THAN IS NECESSARY. IF THE BONDING JUMPERS ARE MOVED TOO MUCJ, IF CAN CAUSE THE LOSS OF TIN PLATING ON THE WIRE BRAID OF THE BONDING JUMPER.
(a)
If there are broken strands in the wire braid, then do the task: Electrical Bonding Jumpers in the Fuel System Replacement.
(b)
If the bonding jumper feels rough, do the task: Electrical Bonding Jumpers in the Fuel System Replacement.
NOTE: This shows there is a loss of tin and possible degradation of the copper in the wire braid.
(c)
If the bonding jumper does not feel rough and there are not signs of flakes of tin or copper fraying of the wire braid, then the bonding jumper is satisfactory.
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Sep 01/02 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-00 Page 201
3. Electrical Bonding Jumpers in the Fuel System Replacement
A. References
(1) SWPM 20-20-00, Electrical Bonds and Grounds
B. Replace the Electrical Bonding Jumper
(1)
Remove the bonding jumper.
(a) Keep all the parts necessary for the installation of the bonding jumper.
(2)
For the bonding jumpers used to bond electrical equipment, follow the applicable installation procedure in the AMM.
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