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View Full Version : effect of Pressed FADEC P/B during flight A320


MeToL
20th Jul 2023, 17:33
Hi guys,
Here is the scenario ; at A320 leap engine

we pushed to FADEC PB for checking of the Oil Quantity. And then we forget to push again. So Fadec PB : ON
And then Crew didnt check that buttons , so they start the fly.

Are there any negative effect to engine or aircraft ?

I meet a lot of situation with Fadec PB ON after landing. But Im just curious about negative effect or nothing ?

spannersatcx
21st Jul 2023, 10:15
Should automatically turn off after 10 minutes or until powered by engine starting.

Tom Sawyer
22nd Jul 2023, 11:41
Without getting wiring diagrams out, and simplifying things a bit - the FADEC pushbutton makes a circuit to supply power from the aircraft supply busbars to the FADEC. Effectively this is the same as when you select IGN/Start on the rotary switch for engine start, so the power supply initially is from the aircraft. During engine start up around 8% or so the FADEC alternator starts to supply power to the FADEC as the primary power source and disconnects it from the aircraft power supply, so I'm pretty sure the pushbutton being selected on shouldn't have any effect. If the alternator fails in flight, the power to the FADEC comes on automatically from the aircraft busbars without needing to select the pushbutton on as relays change over.
Out of interest and it being a non normal situation, did the pushbutton stay illuminated after engine start? I would think it would have gone off.

Amadis of Gaul
26th Jul 2023, 14:18
Without getting wiring diagrams out, and simplifying things a bit - the FADEC pushbutton makes a circuit to supply power from the aircraft supply busbars to the FADEC. Effectively this is the same as when you select IGN/Start on the rotary switch for engine start, so the power supply initially is from the aircraft. During engine start up around 8% or so the FADEC alternator starts to supply power to the FADEC as the primary power source and disconnects it from the aircraft power supply, so I'm pretty sure the pushbutton being selected on shouldn't have any effect. If the alternator fails in flight, the power to the FADEC comes on automatically from the aircraft busbars without needing to select the pushbutton on as relays change over.
Out of interest and it being a non normal situation, did the pushbutton stay illuminated after engine start? I would think it would have gone off.

On our aircraft at least (we have both V2500s and PW NEOs), the light stays on after engine start.