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Thread: MD-11 Eng #2
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Old 6th February 2012 | 15:07
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Flightmech
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Joined: Apr 2002
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From: EGSS
Sorry i misunderstood.

There are 3 AC pumps in the #2 TANK that supply fuel to the #2 engine under normal operation mounted on the rear spar or in underwing cavity. Fuel runs through a shrouded line that runs from the #2 tank through the left wheel well and along the LH sidewall of the aft lower cargo compartment then rearwards and upwards to the #2 engine. There is a circumstance where if a #2 FILL VALVE fault is detected the Fuel System Controller will shut-off the #2 TANK pumps to protect the fuel in the #2 TANK and turn on a TAIL TANK ALTN PUMP which feeds the #2 engine directly from the TAIL TANK. When this fuel is used and the airplane goes to tank-to-engine config it turns the TANK 2 PUMPS back on. Very clever!

This is of course the LP (low pressure) side of the system. The engine itself has a fuel pump (HP) and Hydromechanical Unit (HMU) that controls the fuel going into the fuel nozzles. These are driven by the gearbox on the engine itself.

The #2 ENGINE will not suction feed like 1 and 3. If you lose the boost pumps (TANK 2 and/or TAIL TANK ALTN depending on fuel load/config) the engine will flame out
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