(2)
Suction defueling applies to the main fuel tanks only. Suction from the fuel truck causes fuel from the main fuel tank to flow through the bypass valve of the fuel boost pump into the engine fuel feed manifold. It then goes through the defueling valve, fueling manifold, and the fueling adapter to the fuel truck.
(3)
To defuel a fuel tank with the tank to tank transfer procedure it is necessary to use the defueling valves, fueling shutoff valves, engine fuel shutoff valves, engine fuel crossfeed valve, fuel boost pumps and fuel override pumps. To move the fuel between the fuel tanks the fuel system must be in the subsequent configuration:
(a)
One pump must operate in the fuel tank that supplies fuel.
(b)
The applicable left or right defueling valve must be open.
(c)
The fueling shutoff valve in the fuel tank that gets the fuel must be open.
(4)
If you cannot open the defueling valve in the fuel tank you are defueling, open the engine fuel crossfeed valve and the defueling valve in the opposite fuel tank to do the defueling.
(5)
The fuel quantity indicating system (AMM 28-41-00/001) lets you monitor the defueling at the fueling control panel, P28.
B.
If a fuel tank must be fully defueled, drain the remaining fuel through the drain valve of the fuel sump (AMM 12-11-03/301).
C.
When thunderstorms or lightening are within a 10 mile (16 kilometer) radius of the immediate area, the defueling procedure should stop.
D.
Strong wind conditions can cause a build-up of static electricity. Large charges of static electricity can develop on support equipment while parked as a result of the movement of dust particles and air currents during strong wind conditons. Strong wind conditions can also cause the unwanted movement of items or equipment which can hit the airplane or injure persons. Wind gusts can damage the airplane structure. Fueling procedures should stop if strong wind conditions are present.
TASK 28-26-00-652-044
2. Pressure Defueling (Fig. 201)__________________
A. References
(1) AMM 06-44-00/201, Wings Access Doors and Panels
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