When should I turn off the APU

On take-off after the aircraft leaves the ground, what is the moment when the aircraft’s APU must be turned off. Is there any altitude or do I do the shutdown process after starting the aircraft engines?On take-off after the aircraft leaves the ground, what is the moment when the aircraft’s APU must be turned off. Is there any altitude or do I do the shutdown process after starting the aircraft engines?

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You turn the APU off once the engines are on

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The engines act as electrical generators. The APU is an Auxiliary Power Unit for when the engines are not generating electricity, hence “Off”. The APU should be turned off as soon as the engines are completely started or right before you shut them down at the gate.

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You usually turn the APU off immediately after startup. Turn it back on after landing, once you exit the runway and are taxiing to the gate (this is if you’re shutting down one engine for taxi). Or turn it on just before you turn into the gate (if you’re still running both engines).

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To add to the beautiful answer above, in Infinite Flight, due to the fact that we don’t have ground power units yet, you can leave it on while you’re at the gate. In real life, it is started 5 minutes before pushback and before parking and shutting engines down, then shut down after being connected to the GPU.

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I’d say turn off the APU after one engine is up and running. Then start the second engine.

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APU off after startup.

APU on when you exit the runway.

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Very good thanks!

Okay! Thanks.

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APU Can be shut down after both of ur engines are started
If ur are taxiing with 1 engine I recommend keep the APU ON and wait until ur other engine had started

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APU can and must be used while in the ETOPS (extended twin engine operation) basically for now we’re just gonna say if you are 60 minutes away from the nearest airport that you can land at you’re in the ETOPS phase, during this time the apu must be on and available in case of any failures, but in IF we don’t have failures so you don’t really need to worry about it, unless you’re realism police like me.

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No, you should always have at least two sources of electrical power, so start both engines, then shut down the APU once both are running. That way you always have 2 sources of electrical power for the aircraft.
Start the APU before shutting down an engine. The only exception to that would be if you had to shut down an engine in flight because of a failure, which is obviously not going to happen. In that case though, the APU would be started as soon as time allows.

That may be true. But what I’ve heard and read, one engine is usually enough to provide full electrical power to the plane. But there’s no harm in turning the APU off after both engine startup :)

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That is correct.

Yes, it can, but - at least IRL - what if it fails? Having two sources is for redundancy, as with any critical system.