DA 42 accident

"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

Aircraft using FADEC are relatively recent so why isn't power-loading
prioritized by the electrical system? When an electrical event occurs that
overloads the system capacity, why isn't there enough built-in systems
intelligence onboard to protect the FADEC? If we have enough smarts to
design and build a FADEC why don't we have enough smarts to protect it?

--
Jim Carter
Rogers, Arkansas

"Jim Carter" wrote in message
et...
Aircraft using FADEC are relatively recent so why isn't power-loading
prioritized by the electrical system? When an electrical event occurs that
overloads the system capacity, why isn't there enough built-in systems
intelligence onboard to protect the FADEC? If we have enough smarts to
design and build a FADEC why don't we have enough smarts to protect it?

--
Jim Carter
Rogers, Arkansas

Well said. It should have some fall back. If the coffee maker shorts the
engines quit?

Al G

On 2007-04-24 10:19:56 -0700, "Al G" said:


"Jim Carter" wrote in message
et...
Aircraft using FADEC are relatively recent so why isn't power-loading
prioritized by the electrical system? When an electrical event occurs that
overloads the system capacity, why isn't there enough built-in systems
intelligence onboard to protect the FADEC? If we have enough smarts to
design and build a FADEC why don't we have enough smarts to protect it?

--
Jim Carter
Rogers, Arkansas

Well said. It should have some fall back. If the coffee maker shorts the
engines quit?

Al G

That is a little over the top, really. A look at the electrical diagram
shows the problem: the alternators were not working because the
excitation system failed and the backup generator did not generate
enough power to run everything. Not a problem in most circumstances,
but a pilot should be smart enough not to take off in that condition.

That said, I think protecting essential systems such as the engine is a
good idea. It ought to be part of the fix, along with a bigger
generator, revised engine checklist for starting engine with remote
power (don't, under any circumstances, start both engines this way --
there is no such thing as an emergency take-off) and better pilot
training.
--
Waddling Eagle
World Famous Flight Instructor

On 2007-04-24, Al G wrote:
Well said. It should have some fall back. If the coffee maker shorts the
engines quit?

No, a breaker pops.

Personally, I'm more interested in the accident investigation - all we
know at the moment is the pilot had a discharged battery and the engines
quit.

How do we know that there were not two systems that were failed on the
aircraft - such as the backup generator (which has been mentioned) as
well as the battery? We don't until the accident investigation
concludes.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

"Dylan Smith" wrote ...

Personally, I'm more interested in the accident investigation - all we
know at the moment is the pilot had a discharged battery and the engines
quit.

Here's some mo
http://www.flightglobal.com/Articles...ngine-row.html

"Snowbird" wrote ...

"Dylan Smith" wrote ...

Personally, I'm more interested in the accident investigation - all we
know at the moment is the pilot had a discharged battery and the engines
quit.

Here's some mo
http://www.flightglobal.com/Articles...ngine-row.html


WOW, great link! Tech details down to millisecond voltage dip measurements.
Hurray for the Poor Man's Black Boxes on those Thielerts. Reading this has
tipped me to beginning my research on getting a Graphic Engine Analyzer with
data logging. I only wish I had done this last week at SNF.

Snowbird wrote:
"Dylan Smith" wrote ...

Personally, I'm more interested in the accident investigation - all
we know at the moment is the pilot had a discharged battery and the
engines quit.

Here's some mo
http://www.flightglobal.com/Articles...3371/accident-
ignites-da42-engine-row.html

Well at least neither Diamond nor TAE is saying there is no problem and
trying to blame the pilot. This is an excellent first step in getting any
problem fixed.

Gig 601XL Builder wrote:
Snowbird wrote:
"Dylan Smith" wrote ...

Personally, I'm more interested in the accident investigation - all
we know at the moment is the pilot had a discharged battery and the
engines quit.

Here's some mo
http://www.flightglobal.com/Articles...3371/accident-
ignites-da42-engine-row.html

Well at least neither Diamond nor TAE is saying there is no problem and
trying to blame the pilot. This is an excellent first step in getting any
problem fixed.


As a DA42 owner I hope that the "problem" will get fixed by either
Diamond or TAE. However, note that Diamond did blame the pilot because
the pilot did not use the procedures outlined in the POH to start the
second engine.

Cary

Jim Carter wrote:
Aircraft using FADEC are relatively recent so why isn't power-loading
prioritized by the electrical system? When an electrical event occurs that
overloads the system capacity, why isn't there enough built-in systems
intelligence onboard to protect the FADEC? If we have enough smarts to
design and build a FADEC why don't we have enough smarts to protect it?

That's really the question, though it wouldn't
necessarily have gotten them home safe. Before
the FADEC dropped out, there should have been
an undervolt alarm and load shedding. Then they
could have cranked the gear down if possible.