Apu on during flight?

Does APU need to be always on during flight? My engines shutdown in flight if apu is off…also what is actually apu bleed for?

Plane is a330 headwind

Moved to #self-service as the topic is about requesting help/advice.

APU should be off during flight, the APU Bleed, bleeds compressed air from the APU to the main engine starters to get them started.

Tnx for quick answer, i tought so as week they are not for flight time

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There must be something else you have set incorrectly causing this. Fuel pumps, cross-feeds, etc…

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APU is also used on the ground for various other functions prior to engine start that bleed air supplies.

The APU can be run in-flight up to certain altitudes dependent upon the aircraft. This may be necessary due to other failures or MEL items.