(a)
The (daisy chain) shielded wire connects the HI-Z terminal of the compensator with the HI-Z terminals of all the tank units in the same tank.
(4)
There can be an FQIS HI-Z short circuit or low resistance condition between the center wire and the shield. The cause of the low resistance could be in the main HI-Z wire or in the daisy chain HI-Z wire.
(a)
If the cause of the low resistance can be isolated to the main HI-Z or the daisy chain HI-Z wire, replace the bad bundle.
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(b)
If the resistance problem cannot be isolated to one of the wires, change the two wire bundles.
(c)
If the bundle in the tank is replaced for other reasons, it is
not necessary to change the daisy chain HI-Z wire.Each wire bundle has a connector on one end. The connectors installed on fuel tank bulkheads in the tank are found as follows:
(1)
Connectors for wing tank wire bundles are installed on the front spar bulkhead of the inboard tank.
(2)
Connectors for the center tank are installed on the aft bulkhead of
the center tank in the left wing gear wheel well.The other end of each wire bundle is connected to fuel quantity tank units and compensator, densitometer or single point sensors installed in the fuel tank.The wire bundle routing for the wing reserve tank goes through the inboard and outboard main tanks.
(1)
Internal access to all three wing tanks is necessary for the
replacement of a reserve tank wire bundle.The wire bundle routing for the outboard main tank goes through the inboard main tank.
(1)
Internal access to the inboard and outboard main tanks is necessary
for replacement of the outboard tank wire bundles.Open the applicable fuel tank access doors to get access to the fuel tank wire bundle and fuel quantity components.
(1)
Some of the equipment found in the fuel tanks is not adjacent to a fuel tank access door.
(2)
To get access to equipment away from an access door, persons must:
(a)
Get into the tank through the nearest access door.
(b)
Go through rib access openings and spar access openings in the
mid spar.Wire bundle routing that goes through a tank divider or tank baffle will have an electrical seal installed at the barrier.
(1)
For replacement of the electrical seal, refer to Seals and Sealing
(AMM 51-31-01/201).A wire bundle can have critical location markers installed on the bundle.
(1)
After the wire bundle has been pre routed, it should be adjusted to locate its marker on the necessary rib.
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K. Start at the tank component end when you remove the wire bundle. Remove the bundle in the direction of the bulkhead connector.
L. It is necessary to prepare the fuel tanks for entry (AMM 28-11-00/201) to replace a FQIS wire bundle.
(1)
The procedure (AMM 28-11-00/201) supplies instructions to prepare the airplane before the wire bundle replacement is started.
(2)
The procedure references that follow are a part of Fuel Tank - MP (AMM 28-11-00/201).
(a)
AMM 20-41-01/201, Static Ground
(b)
AMM 24-22-00/201, Manual Control
(c)
AMM 28-11-02/401, Access Doors
(d)
AMM 28-26-00/201, Defueling
(3)
The procedure references that follow are part of Defueling (AMM 28-26-00/201).
(a)
AMM 07-11-08/201, Cargo & Tail Fuel Load Support
(b)
AMM 27-81-00/201, Leading Edge Flap Systems
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