Larry,

What powers the FADEC in the event of an electrical system failure?


A battery. Yes, in the case of the DA-42, this was implemented lousily,
as someone found out the hard way when he didn't follow the POH. The
system is being changed to prevent fools from...
Other installations are different.

In case you worry about this "single point of failure", your Lyc or
Continental has tons of them, too.

--
Thomas Borchert (EDDH)