DA 42 accident

On 2007-04-23 11:32:17 -0700, "Gig 601XL Builder"
wrDOTgiaconaATsuddenlink.net said:

Neil Gould wrote:
Recently, Karl-Heinz Kuenzel posted:

Neil Gould schrieb:
I have a somewhat different take on this event. [...]
I don't find it
surprising that the props feathered in this situation, and would
even say that it would be the expected behavior, rather than a fluke
of some kind. I would find it surprising if Diamond doesn't have
adequate information about their flight systems in the POH to inform
the pilot of this possibility.


OK Neil.

You find it in the article.

My Deutsch is far too rusty to find it in the article. ;-)

POH - Under - abnormal operating procedures - 4B.7 STARTING ENGINE
WITH EXTERNAL POWER - #13 Opposite engine ..... START WITH NORMAL
PROCEDURE

That is it.

That's fine for starting the engines, but that isn't the only issue,
is it?

Is there nothing in the POH about the electrically powered items
(landing gear, FADEC, etc.)? If there is, it shouldn't require an EE
degree to realize that one should be concerned about the condition of
the batteries, charging, etc. if one has to "jump start" the engine,
or to realize that something critical is in need of attention.

Maybe I'm just an overly cautious type. ;-)

Neil

I agree that if you are flying what is basically an all electric aircraft
and you have an electrical problem on the ground that you should take extra
care before flight BUT, there should be some system in place that doesn't
allow the gear switch, landing lights or any other electrically operated
item to become an OFF switch with out some damn significant warning.

Either that, or put in a big enough generator to run everything. Good
grief, this airplane had batteries, backup batteries, two alternators,
and a generator. It had warning lights and systems which should have
told the pilot that only the generator was working. The pilot should
have known that the generator does not generate full electrical power.
How much redundancy is enough? You spend a fortune on a plane and don't
learn the emergency procedures? What's up with that?
--
Waddling Eagle
World Famous Flight Instructor

On 2007-04-23 11:20:24 -0700, "Neil Gould" said:

Recently, Karl-Heinz Kuenzel posted:

Neil Gould schrieb:
I have a somewhat different take on this event. [...]
I don't find it
surprising that the props feathered in this situation, and would
even say that it would be the expected behavior, rather than a fluke
of some kind. I would find it surprising if Diamond doesn't have
adequate information about their flight systems in the POH to inform
the pilot of this possibility.


OK Neil.

You find it in the article.

My Deutsch is far too rusty to find it in the article. ;-)

POH - Under - abnormal operating procedures - 4B.7 STARTING ENGINE
WITH EXTERNAL POWER - #13 Opposite engine ..... START WITH NORMAL
PROCEDURE

That is it.

That's fine for starting the engines, but that isn't the only issue, is
it?

Is there nothing in the POH about the electrically powered items (landing
gear, FADEC, etc.)? If there is, it shouldn't require an EE degree to
realize that one should be concerned about the condition of the batteries,
charging, etc. if one has to "jump start" the engine, or to realize that
something critical is in need of attention.

Maybe I'm just an overly cautious type. ;-)

Neil

No, you are not overly cautious. Every pilot should be taught that if
the battery is dead and you start the plane with external power, the
first thing you check is to see if the alternator(s) is charging. If it
isn't, either the alternator is broken or the battery did not excite
the alternator.

Now, if the excitation system did not excite the alternator, why didn't
the remote starting system do it? It should have. I would want a look
at the power cart, its cables, and the wiring to the port on the
airplane. In fact, especially the latter, as it could provide a clue as
to why the excitation battery died in the first place.
--
Waddling Eagle
World Famous Flight Instructor

"C J Campbell" wrote in message
news:2007042418505437709-christophercampbell@hotmailcom...
On 2007-04-23 11:20:24 -0700, "Neil Gould" said:

Recently, Karl-Heinz Kuenzel posted:

Neil Gould schrieb:
I have a somewhat different take on this event. [...]
I don't find it
surprising that the props feathered in this situation, and would
even say that it would be the expected behavior, rather than a fluke
of some kind. I would find it surprising if Diamond doesn't have
adequate information about their flight systems in the POH to inform
the pilot of this possibility.


OK Neil.

You find it in the article.

My Deutsch is far too rusty to find it in the article. ;-)

POH - Under - abnormal operating procedures - 4B.7 STARTING ENGINE
WITH EXTERNAL POWER - #13 Opposite engine ..... START WITH NORMAL
PROCEDURE

That is it.

That's fine for starting the engines, but that isn't the only issue, is
it?

Is there nothing in the POH about the electrically powered items
(landing
gear, FADEC, etc.)? If there is, it shouldn't require an EE degree to
realize that one should be concerned about the condition of the
batteries,
charging, etc. if one has to "jump start" the engine, or to realize that
something critical is in need of attention.

Maybe I'm just an overly cautious type. ;-)

Neil

No, you are not overly cautious. Every pilot should be taught that if
the battery is dead and you start the plane with external power, the
first thing you check is to see if the alternator(s) is charging. If it
isn't, either the alternator is broken or the battery did not excite
the alternator.

Now, if the excitation system did not excite the alternator, why didn't
the remote starting system do it? It should have. I would want a look
at the power cart, its cables, and the wiring to the port on the
airplane. In fact, especially the latter, as it could provide a clue as
to why the excitation battery died in the first place.
--
Waddling Eagle
World Famous Flight Instructor

Actually, it may be possible to start some older airplanes on external
power, disconnect the power cart, and then not have enough voltage to engage
the alternator solenoid. I no longer recall the exact circumstances, and
don't have a manual available, but I believe that it was even possible to
induce the problem on a plain old Cessna 172.

Peter

Recently, C J Campbell posted:

On 2007-04-23 11:20:24 -0700, "Neil Gould"
said:

Recently, Karl-Heinz Kuenzel posted:

Neil Gould schrieb:
I have a somewhat different take on this event. [...]
I don't find it
surprising that the props feathered in this situation, and would
even say that it would be the expected behavior, rather than a
fluke of some kind. I would find it surprising if Diamond doesn't
have adequate information about their flight systems in the POH to
inform the pilot of this possibility.


OK Neil.

You find it in the article.

My Deutsch is far too rusty to find it in the article. ;-)

POH - Under - abnormal operating procedures - 4B.7 STARTING ENGINE
WITH EXTERNAL POWER - #13 Opposite engine ..... START WITH NORMAL
PROCEDURE

That is it.

That's fine for starting the engines, but that isn't the only issue,
is it?

Is there nothing in the POH about the electrically powered items
(landing gear, FADEC, etc.)? If there is, it shouldn't require an EE
degree to realize that one should be concerned about the condition
of the batteries, charging, etc. if one has to "jump start" the
engine, or to realize that something critical is in need of
attention.

Maybe I'm just an overly cautious type. ;-)

Neil

No, you are not overly cautious. Every pilot should be taught that if
the battery is dead and you start the plane with external power, the
first thing you check is to see if the alternator(s) is charging. If
it isn't, either the alternator is broken or the battery did not
excite the alternator.

Now, if the excitation system did not excite the alternator, why
didn't the remote starting system do it? It should have. I would want
a look
at the power cart, its cables, and the wiring to the port on the
airplane. In fact, especially the latter, as it could provide a clue
as to why the excitation battery died in the first place.

If the alternators weren't excited, wouldn't the pilot be looking at two
alternator warning lights prior to take off? Does the aircraft have an
ampmeter?

Neil

"Neil Gould" wrote ...

If the alternators weren't excited, wouldn't the pilot be looking at two
alternator warning lights prior to take off?


According to the AFM there are amber caution lights for alternator failure,
so yes.


Does the aircraft have an
ampmeter?



Again according to the AFM, yes, but notably, it is not on the MFD's default
engine display page but on the "System" page together with the voltmeters.
You need to push a button to see it. However, the checklist requires you to
have a look at the "System" page after engine start as well as before
take-off, so if the checklist is followed a fault would not go unnoticed.

In the other scenario posited by the article, i.e. an unconnected main
battery, things become interesting. In this scenario the ammeters would
presumably show "normal" values, i.e the instantaneous consumption of the
electrical devices. In this case the voltmeter would really be essential .
The AFM says about the voltmeters: "Under normal operating conditions the
alternator voltage is shown, otherwise it displays the 'main'-battery
voltage." So the voltmeters presumably measure the bus voltage, and in this
scenario (battery disconnected) they would probably show an abnormal voltage
which could alert the pilot. I'm no expert here, but I seem to recall
stories of batteries failing in-flight and how that can be seen from the
voltmeter.

Also, in this case, there seems to be no way of positively checking the
actual, pure main battery voltage, because according to the schematic the
main battery relay needs power from the battery itself to operate and
connect to the battery bus. Or then I'm missing something......

Recently, Snowbird posted:

"Neil Gould" wrote ...

Does the aircraft have an
ampmeter?



Again according to the AFM, yes, but notably, it is not on the MFD's
default engine display page but on the "System" page together with
the voltmeters. You need to push a button to see it. However, the
checklist requires you to have a look at the "System" page after
engine start as well as before take-off, so if the checklist is
followed a fault would not go unnoticed.

I would think that this preflight requirement has implications for this
accident.

In the other scenario posited by the article, i.e. an unconnected
main battery, things become interesting. In this scenario the
ammeters would presumably show "normal" values, i.e the instantaneous
consumption of the electrical devices.

If the alternators are working, the ammeters should show a higher than
normal postive value, as the battery is not putting a normal load on the
charging system. That, too, would stop me from taking off.

In this case the voltmeter
would really be essential . The AFM says about the voltmeters: "Under
normal operating conditions the alternator voltage is shown,
otherwise it displays the 'main'-battery voltage." So the voltmeters
presumably measure the bus voltage, and in this scenario (battery
disconnected) they would probably show an abnormal voltage which
could alert the pilot. I'm no expert here, but I seem to recall
stories of batteries failing in-flight and how that can be seen from
the voltmeter.

Hmm. I'd think the alternator voltage would always be shown unless the
engines aren't running, and then the bus voltage is shown. A look at the
schematic could reveal which case is correct.

Also, in this case, there seems to be no way of positively checking
the actual, pure main battery voltage, because according to the
schematic the main battery relay needs power from the battery itself
to operate and connect to the battery bus. Or then I'm missing
something......

I'd think that checking when the engines are not running would show the
main battery voltage level. If the battery is dead, of course, the relay
wouldn't have power to connect to the bus.

Neil

Neil Gould wrote:
Recently, Friedrich Ostertag
posted:

Karl-Heinz Kuenzel wrote:
Hi.

Here in Germany we had an accident with a brand new DA 42 in Speyer
(EDRY) on 3-4-07 during take off.

It seems, that the battery was down and both engine were started
with remote power.
After take off when retracting the gear, the props feathered and
both engines stopped.

You can read about that accident in German (sorry) in
www.pilotundflugzeug.de

First hearing about that accident and the background, I could not
believe it.

I don't even know where to start. How can an aircraft, that depends
on electrical power for the operation of it's engines, be airworthy
without fully redundant electrical systems? While in this particular
case the pilot might have noticed the problem, had he meticuously
follow procedures and started the second engine at the plane's own
power, it is quite easy to find failure modes that would go unnoticed
inflight, yet cause double engine failure at the instant the gear is
lowered on final. Lead batteries are known to occasionally go flat
suddenly, once the buildup of oxide makes contact between the lead
elements. Happened to me in the car once. The engine (a diesel with
mechanical injection pump) ran happily without me even noticing the
failure until I shut it down. When I turned the power back on again,
not even the lights in the dashboard would light up, it was
completely and utterly dead.

I would never have thought that they cut corners like that at
Diamond. I Hope this will not create a lot of mistrust in
aerodiesels, as it is not a diesel issue. I guess you could call it a
FADEC issue if you wanted, however it really is an issue of
redundancy of essential systems, and easily solveable as such.

I have a somewhat different take on this event. It appears to me that
the pilot didn't sufficiently understand his aircraft or the
implications of the symptoms he observed. Knowing that there was
insufficient power to start the engines, that the engine & prop
controls were dependent on electric power and that the landing gear
used an electric motor would have stopped me from taking off until
the battery/electrical system problem was addressed.

Well said, and I wouldn't disagree. However, the very same potentially
deadly failure could occur anytime the battery fails inflight, with no way
for the pilot to know about it before he actually hits the button to lower
the gear. That alone appears to me to be a major design flaw that would make
me pretty uncomfortable, batteries are known to fail suddenly sometimes. I
really would expect redundancy in something as critical as the power supply
for the fadec to be a requirement for airworthyness. Why have two sets of
magnetos on the typical SI-engine? It's just an electrical system, too...
Why have a twin engined aircraft?

I don't find it
surprising that the props feathered in this situation, and would even
say that it would be the expected behavior, rather than a fluke of
some kind.

If you are saying that a shut-down is to be expected when the power supply
on a fadec controlled engine fails, you are right. No modern engine will
continue running without electrical power. Even on a diesel with common rail
fuel supply (as the thielert is) without electricity no fuel injection is
possible.

regards,
Friedrich

Friedrich Ostertag wrote:
Neil Gould wrote:
Recently, Friedrich Ostertag
posted:

Karl-Heinz Kuenzel wrote:
Hi.

Here in Germany we had an accident with a brand new DA 42 in Speyer
(EDRY) on 3-4-07 during take off.

It seems, that the battery was down and both engine were started
with remote power.
After take off when retracting the gear, the props feathered and
both engines stopped.

You can read about that accident in German (sorry) in
www.pilotundflugzeug.de

First hearing about that accident and the background, I could not
believe it.
I don't even know where to start. How can an aircraft, that depends
on electrical power for the operation of it's engines, be airworthy
without fully redundant electrical systems? While in this particular
case the pilot might have noticed the problem, had he meticuously
follow procedures and started the second engine at the plane's own
power, it is quite easy to find failure modes that would go unnoticed
inflight, yet cause double engine failure at the instant the gear is
lowered on final. Lead batteries are known to occasionally go flat
suddenly, once the buildup of oxide makes contact between the lead
elements. Happened to me in the car once. The engine (a diesel with
mechanical injection pump) ran happily without me even noticing the
failure until I shut it down. When I turned the power back on again,
not even the lights in the dashboard would light up, it was
completely and utterly dead.

I would never have thought that they cut corners like that at
Diamond. I Hope this will not create a lot of mistrust in
aerodiesels, as it is not a diesel issue. I guess you could call it a
FADEC issue if you wanted, however it really is an issue of
redundancy of essential systems, and easily solveable as such.

I have a somewhat different take on this event. It appears to me that
the pilot didn't sufficiently understand his aircraft or the
implications of the symptoms he observed. Knowing that there was
insufficient power to start the engines, that the engine & prop
controls were dependent on electric power and that the landing gear
used an electric motor would have stopped me from taking off until
the battery/electrical system problem was addressed.

Well said, and I wouldn't disagree. However, the very same potentially
deadly failure could occur anytime the battery fails inflight, with no way
for the pilot to know about it before he actually hits the button to lower
the gear. That alone appears to me to be a major design flaw that would make
me pretty uncomfortable, batteries are known to fail suddenly sometimes. I
really would expect redundancy in something as critical as the power supply
for the fadec to be a requirement for airworthyness. Why have two sets of
magnetos on the typical SI-engine? It's just an electrical system, too...
Why have a twin engined aircraft?

I don't find it
surprising that the props feathered in this situation, and would even
say that it would be the expected behavior, rather than a fluke of
some kind.

If you are saying that a shut-down is to be expected when the power supply
on a fadec controlled engine fails, you are right. No modern engine will
continue running without electrical power. Even on a diesel with common rail
fuel supply (as the thielert is) without electricity no fuel injection is
possible.

regards,
Friedrich


This is a cut and paste from a AOPA story on the plane

There are three batteries. The main battery is a 24-volt 10-amp-hour
size. Electrical power is provided by two 24-volt 60-amp alternators —
one on each engine. There also is a 24-volt 1.3-amp-hour
alternator-excitation battery to provide alternator start-up
(excitation) voltage if the main battery is discharged below the
required excitation threshold. The third battery is a stand-alone
emergency battery that powers the electric artificial horizon and an
instrument floodlight for one and a half hours.

The question then become if there are 2 60AMP alternators and a single
10AMP-hour battery how could the battery being dead cause the issue. I
think there is much more here then meets the eye. Perhaps we should
wait for more data before we jump to conclusions.

On 2007-04-24 14:47:11 -0700, "Friedrich Ostertag"
said:

Neil Gould wrote:
Recently, Friedrich Ostertag
posted:

Karl-Heinz Kuenzel wrote:
Hi.

Here in Germany we had an accident with a brand new DA 42 in Speyer
(EDRY) on 3-4-07 during take off.

It seems, that the battery was down and both engine were started
with remote power.
After take off when retracting the gear, the props feathered and
both engines stopped.

You can read about that accident in German (sorry) in
www.pilotundflugzeug.de

First hearing about that accident and the background, I could not
believe it.

I don't even know where to start. How can an aircraft, that depends
on electrical power for the operation of it's engines, be airworthy
without fully redundant electrical systems? While in this particular
case the pilot might have noticed the problem, had he meticuously
follow procedures and started the second engine at the plane's own
power, it is quite easy to find failure modes that would go unnoticed
inflight, yet cause double engine failure at the instant the gear is
lowered on final. Lead batteries are known to occasionally go flat
suddenly, once the buildup of oxide makes contact between the lead
elements. Happened to me in the car once. The engine (a diesel with
mechanical injection pump) ran happily without me even noticing the
failure until I shut it down. When I turned the power back on again,
not even the lights in the dashboard would light up, it was
completely and utterly dead.

I would never have thought that they cut corners like that at
Diamond. I Hope this will not create a lot of mistrust in
aerodiesels, as it is not a diesel issue. I guess you could call it a
FADEC issue if you wanted, however it really is an issue of
redundancy of essential systems, and easily solveable as such.

I have a somewhat different take on this event. It appears to me that
the pilot didn't sufficiently understand his aircraft or the
implications of the symptoms he observed. Knowing that there was
insufficient power to start the engines, that the engine & prop
controls were dependent on electric power and that the landing gear
used an electric motor would have stopped me from taking off until
the battery/electrical system problem was addressed.

Well said, and I wouldn't disagree. However, the very same potentially
deadly failure could occur anytime the battery fails inflight, with no way
for the pilot to know about it before he actually hits the button to lower
the gear.

No. This was not caused by a battery failure per se. It was a failure
of the electrical excitation system which starts the alternators. That
should prevent the engine from starting and it did. However, the pilot
bypassed that by starting both engines (a big no-no) with external
power. The battery is not actually used in-flight to keep the engines
running. The alternators are used for that, with a generator backup,
and finally a battery for backup, with warning lights all over the
place. Once the plane is flying, assuming the alternators start out
working, you would practically have to have a major electrical fire to
duplicate the problem. But take off without a working alternator and
you have a big problem.


--
Waddling Eagle
World Famous Flight Instructor

Recently, Friedrich Ostertag posted:

Neil Gould wrote:
Recently, Friedrich Ostertag
posted:

Karl-Heinz Kuenzel wrote:
Hi.

Here in Germany we had an accident with a brand new DA 42 in Speyer
(EDRY) on 3-4-07 during take off.

It seems, that the battery was down and both engine were started
with remote power.
After take off when retracting the gear, the props feathered and
both engines stopped.

You can read about that accident in German (sorry) in
www.pilotundflugzeug.de

First hearing about that accident and the background, I could not
believe it.

I don't even know where to start. How can an aircraft, that depends
on electrical power for the operation of it's engines, be airworthy
without fully redundant electrical systems? While in this particular
case the pilot might have noticed the problem, had he meticuously
follow procedures and started the second engine at the plane's own
power, it is quite easy to find failure modes that would go
unnoticed inflight, yet cause double engine failure at the instant
the gear is lowered on final. Lead batteries are known to
occasionally go flat suddenly, once the buildup of oxide makes
contact between the lead elements. Happened to me in the car once.
The engine (a diesel with mechanical injection pump) ran happily
without me even noticing the failure until I shut it down. When I
turned the power back on again, not even the lights in the
dashboard would light up, it was completely and utterly dead.

I would never have thought that they cut corners like that at
Diamond. I Hope this will not create a lot of mistrust in
aerodiesels, as it is not a diesel issue. I guess you could call it
a FADEC issue if you wanted, however it really is an issue of
redundancy of essential systems, and easily solveable as such.

I have a somewhat different take on this event. It appears to me that
the pilot didn't sufficiently understand his aircraft or the
implications of the symptoms he observed. Knowing that there was
insufficient power to start the engines, that the engine & prop
controls were dependent on electric power and that the landing gear
used an electric motor would have stopped me from taking off until
the battery/electrical system problem was addressed.

Well said, and I wouldn't disagree. However, the very same potentially
deadly failure could occur anytime the battery fails inflight, with
no way for the pilot to know about it before he actually hits the
button to lower the gear. That alone appears to me to be a major
design flaw that would make me pretty uncomfortable, batteries are
known to fail suddenly sometimes. I really would expect redundancy in
something as critical as the power supply for the fadec to be a
requirement for airworthyness. Why have two sets of magnetos on the
typical SI-engine? It's just an electrical system, too... Why have a
twin engined aircraft?

I agree that a failure mode allowing in-flight engine shutdown due to low
battery voltage implies that there may be an aspect of the design that
needs attention. On the other hand, the dead battery could have been a
symptom of a larger problem, and the existing design really is quite
reasonable.

I don't find it
surprising that the props feathered in this situation, and would even
say that it would be the expected behavior, rather than a fluke of
some kind.

If you are saying that a shut-down is to be expected when the power
supply on a fadec controlled engine fails, you are right. No modern
engine will continue running without electrical power. Even on a
diesel with common rail fuel supply (as the thielert is) without
electricity no fuel injection is possible.

Right, however, the alternator should be able to supply the electricity
needed to keep the engines running. It wouldn't surprise me to find that
the a breaker had popped when the landing gear was retracted and the pilot
didn't think to reset it.

Neil