Twin or Single

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Boatguy
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Re: Twin or Single

Post by Boatguy »

Rich wrote:
Boatguy wrote: I like facts, but if “sketchy evidence” is all we have, let’s hear it. Please expand on your assertion regarding the NG.
NTSB accident reports, ASN wiki, and the FAA Accident/Incident reports. No reports at all for anything but the NG, for which there are several, where power loss is a factor. That's why it's sketchy.

Edit: It appears there is now 1 (quite recent) M1A power loss in the NTSB accident DB.
I searched the NTSB database for all Diamond and got 143 hits. Of those 5 were for NG (40 and 42) and 2 were for partial power loss. The other three were a hard landing, runway excursion and taxiing collision; pure pilot error. No fatals in the 5 NGs.

Both power loss reported ECU failures, but I'm not sure if that's a cause or symptom.

There were 138 other Diamond accidents that were not NG. I did not view them all to see the causes, but within 138 it seems likely that more than 2 were power related which seems to contradict your assertion that the NG is the "leader in power failures".

Not saying it can't happen, just not sure the NG is the leader.
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shorton
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Re: Twin or Single

Post by shorton »

Keep in mind there aren’t many DA40NG’s currently on the FAA registry (something like 20 last time I looked). On the other hand, there have been over 700 Lycoming DA40’s flying around the U.S. for a long time - all but a few more than 10 years old.

While there may be 1 or 2 Lycoming DA40 engine failures (the recent one is the first I’ve seen), the fact that there are 2 documented DA40NG engine failures out of that very small sample size is not a great statistic.

I like the Austro engine a lot, I just want two of them.
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Rich
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Re: Twin or Single

Post by Rich »

Boatguy wrote:
There were 138 other Diamond accidents that were not NG. I did not view them all to see the causes, but within 138 it seems likely that more than 2 were power related which seems to contradict your assertion that the NG is the "leader in power failures".

Not saying it can't happen, just not sure the NG is the leader.
Seems likely? BTW, an outsize portion of the Diamond accidents are DA20's and there are also a scattering of other non-DA40s in there.

The tricky part about finding power loss incidents is they aren't necessarily reported in the NTSB DB if the incident results in an otherwise uneventful landing. They show up in the local news and the FAA Accident/incident DB, but then they age off and don't appear easily.

There was at least one other known NG power loss not in the NTSB DB, because it resulted in a successful off-field landing. Thus it didn't get put in there. I have in fact looked at lots of these accidents and this recent DA40-180 power loss is the first one I've seen.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: Twin or Single

Post by Rich »

Just for grins I went through every DA40 entry in the NTSB database. This isn't as daunting as one might think. Listing all Diamond entries produces 143 entries on 15 pages of results. But only 38 of those entries are DA40's: 35 DA40-180s and 3 NG's. The 180 entries are, of course, spread out across some 16 years of history.

Entries where power loss is referenced: DA40-180's: 1, DA40 NG's: 2.

DA20's constitute the substantial majority of the entries and I didn't go through those. Conceivably there could be some power loss incidents among them.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Twin or Single

Post by Colin »

I don't trust that database. I was originally in it (flat tire on my delivery flight to North Las Vegas, departed the runway and took out a taxi light; damaged my wheel pant). Now I no longer show up. Make of that what you will.
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Rich
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Re: Twin or Single

Post by Rich »

Colin wrote:I don't trust that database. I was originally in it (flat tire on my delivery flight to North Las Vegas, departed the runway and took out a taxi light; damaged my wheel pant). Now I no longer show up. Make of that what you will.
OK, name a more reliable one. I can find the wreck of my PA28 from back in 1983 in it.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: Twin or Single

Post by Rich »

One of the limitations of the NTSB data is it does not necessarily include every single mishap. From time to time various entries might be culled that were initially put in there, perhaps inadvertently. In fact there is currently an entry for a DA40 that was merely a problem with the prop governor. No excitement, just a precautionary return to the airport because of a non-threatening problem with managing RPM. I myself had a similar set of problems about 9 years ago, in that case with the prop itself. Never reported to FAA or NTSB, just repaired by MT.

In Part 830, the NTSB defines an accident as:

- an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and when all such passengers have disembarked,
- in which any person suffers death or serious injury,
- in which the aircraft receives substantial damage.

Substantial damage means damage or failure which adversely affects the structural strength, performance, or flight characteristics of the aircraft. This type of damage would normally require major repair or replacement of the affected component.


There are certain items that are not considered “substantial damage” by the NTSB. These include:

Engine failure or damage limited to an engine if only one engine fails or is damaged
Bent fairings or cowling
Dented aircraft skin or small punctured holes in the skin or fabric
Ground damage to rotor or propeller blades
Damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Twin or Single

Post by TimS »

Colin wrote:I don't trust that database. I was originally in it (flat tire on my delivery flight to North Las Vegas, departed the runway and took out a taxi light; damaged my wheel pant). Now I no longer show up. Make of that what you will.
NTSB has rules about accidents/incidents that remain in the database. Often, incidents that only get a little bent metal or fiberglass are purged after a year or two. I forget the exact criteria, but this has come up in a few other forums.
Personally, considering the cost of disk space, I would like to see NTSB set a flag on those cases and just remove them from the standard queries.

Tim
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Re: Twin or Single

Post by jprhode »

Twin or single what is also a good question. A single PT6 is for sure more reliable than 2x piston anything, NG or otherwise, and without the multi engine minus one engine complexity. It’s not as emotionally satisfying as having a spare engine, but the math is better. I like math.
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Colin
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Re: Twin or Single

Post by Colin »

Statistically a single PT6 is better than two of them. Odd, but true.
Colin Summers, PP Multi-Engine IFR, ~3,000hrs
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