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AF330
11th Oct 2014, 05:05
Hi!
I was learning the FADEC system (ECU, HMU, VSV, LPTCC...). But I learnt that the generator of the ECU had to be charged. So 2 questions:

1) Is it charger with DC? DC ESS? DC BAT? ...
2) Is the DC BAT charged? Or is it energy coming from DC 1 only?

Thanks

Fursty Ferret
13th Oct 2014, 09:39
FCOM says magnetic alternator so presumably no field coils required.

Unless you're using the word "charged" in a strange way... If the internal generator is not supplying sufficient power to the FADEC, channel A will be supplied from the DC ESS BUS; channel B will be supplied by the BAT BUS and DC BUS 2 for engines 1 and 2 respectively.

Amadis of Gaul
13th Oct 2014, 15:47
Seems to me that by "charged" he means "powered".

AF330
13th Oct 2014, 17:42
Thanks,
Yes, I mean "powered", sorry!

"If the internal generator is not supplying sufficient power to the FADEC, channel A will be supplied from the DC ESS BUS; channel B will be supplied by the BAT BUS"

Ok, I get it till here!

DC BUS 2 for engines 1 and 2 respectively.

But what is powered by this?

Thanks

Amadis of Gaul
13th Oct 2014, 18:49
What is powered by what? What are you asking?

Mecaniquito84
14th Oct 2014, 06:42
Every FADEC control engine have a PMA, permanet magnet generator driven by corresponding engine gear box.
Long time did not work on 320, correct me is I'm wrong, but the logic is more or less:
At plane power up, FADEC will be powered by a/c system for a short time, then auto switched off since on ground FADEC, which is cooled by engine air flow, may overheats. Maintenance/Crew my bypass this by a dedicated FADEC test sw, for instance, to know is EGT is low enough for next flight or in other airbys, to check oil qty indication.

When eng is started, Fuel sw on, FADEC is again powered by a/c buses, at n2 =7% (repeat out of memory), PMA have enough rpm to generate power to FADEC removing a/c power bus from it. Should PMA fail, a/c power takes place till engine shut down, where you are AOG with a related mssg.

AF330
15th Oct 2014, 19:19
Thanks a lot! Got it! ;)