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It is stated that when the Electric Pump push button is depressed, the electric pump is automatically running as long as the cargo door selector valve is set to either OPEN or CLOSE position.

During this period, the operation of other systems powered by the Yellow Hydraulic system is inhibited except Alternate Brake and Thrust Reverser of ENG #2.

  • The Alternate Braking is understandably essential as it stops aircraft from moving, and cargo door operation is considered that aircraft is in parking, not landing phase when the thrust reversers are only being used.

My question here is why thrust reverser ENG#2 needs to be operative during cargo door operation.

Thanks for your answers. enter image description here

(Source: Training Manual A320 Family)

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    $\begingroup$ It doesn't need to be operative, it just isn't inoperative. $\endgroup$
    – GdD
    Apr 12, 2020 at 9:01
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    $\begingroup$ My guess from looking at distribution diagrams is that there simply isn't a valve in between the alternate braking and engine 2 thrust reverser that could close, but I'm not sure why that is the case? $\endgroup$
    – Bianfable
    Apr 12, 2020 at 10:24

1 Answer 1

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“It is stated that when the Electric Pump push button is depressed, the electric pump is automatically running as long as the cargo door selector valve is set to either OPEN or CLOSE position”

This is not correct. Cargo door operation will automatically energize the Elec Pump while it is in the OFF position. (not depressed)

“My question here is why thrust reverser ENG#2 needs to be operative during cargo door operation”

It doesn’t need to be operative. It needs to be Not Inhibited, in case there is a malfunction.

The cargo door uses the Yellow system. It is designed to be used on the ground even with the Electric Pump in the OFF position. The pump will come on automatically in this case to supply hydraulic power to the cargo door. It will inhibit all the other items on the yellow system to insure adequate hydraulic power to the cargo door.

BUT......If there was a malfunction in the Cargo Door system while in flight, it could possibly cause the Yellow Elec Pump to engergize while it is in the OFF position. If that were to happen, it is designed to inhibit all items on the Yellow system. That would be bad, so they designed the switch to inhibit everything except Alt Brakes and #2 Reverse.

This situation could only happen if the Yellow Elec Pump was automatically commanded ON while in the OFF position.

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