225 power
HS, its rather complicated,
2 alternators /TRUs are the normal source of generated power. If one fails, the other can supply all reasonable needs automatically.
If both fail, some non-essential services are automatically shed. The pilot has to select the hydraulic generator manually and some further services are shed but for example its still happy to do a hands-off ILS with auto-level-off at the bottom.
If that fails as well, you are automatically down to the main battery which obviously has limited life. If that fails you are automatically down to the emergency battery. You lose a lot of stuff at that point but at least retain the standby horizon, airspeed, altitude display. Electrical power for the FADECs / Engine governing would be assured by the small alternators on the engines.
These engine alternators normally power the FADECs after start, but if they fail the system automatically reverts to airframe power - any of the power sources above except the standby battery. But these engine FADEC alternators are small and can't be used to power anything else on the airframe.
So although there are 7 power sources, they can't all be used to power everything since the smaller ones have their power limits. However I mentioned it to show that helis already have multiple power sources, so the concept is there even if the detail would have to change for FBW.
Last edited by HeliComparator; 23rd April 2013 at 11:20.