"Neil Gould" wrote in message
.. .
Recently, Cary posted:

I just received an e-mail today from Diamond explaining the situation.
Since the engines are FADEC controlled, the dead battery did not have
enough power to retract the landing gear and keep the engines going.
The e-mail also stated that Diamond is looking into making some
changes.

Cary (DA42 owner)

The actual wording of that email would be interesting. I'd think that the
FADEC keeps the fuel flow and props configured, and that the current draw
of the landing gear motor(s) probably shut the FADEC down due to low
voltage. While that could be addressed with a different power
configuration (a separate battery for the FADEC, for example), it may also
introduce more failure modes and more factors to take into consideration
during pre-flight.

Neil (NOT a DA42 owner)


I have to admit that I am a little surprised that (or if) they did not
include a little magneto/generator in/on each engine, sufficient to power
the FADEC and pumps, to prevent the sort of incident described.

OTOH, I am trying to remember whether larger aircraft systems behave in a
similar way, and I must admit that I do not recall.

In any case, it is very interesting and most unfortunate for those involved,
and we will all know a lot more is the investigation progresses; and a lot
of what we learn will be equally applicable to FADEC equipped spark ignition
engines. It will obviously be worth the effort, over the longer term, since
fuel savings translate readily into payload and range--which is usually
worth more than the fuel savings.

Peter