DA40NG

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Keith M
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Re: DA40NG

Post by Keith M »

When I was choosing between an SR20 and a DA40, 12 years ago, my decision was heavily influenced by the number of Cirrus aircraft that caught fire after accidents. That doesn't seem to be a factor now that pilots are encouraged to pull the chute rather than attempt a forced landing, although they still use the interior of their wings as fuel tanks. Having said that, I think Diamond took their reputation for primary safety too casually, and let it slip with the heavyweight Austro engine. Compared with Cirrus, they were also very late in providing the GFC700 autopilot and AmSafe seatbelts.
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Re: DA40NG

Post by TimS »

There are some very fascinating studies on car safety.
Volvo in the USA has had a reputation for safety for decades. Did you know when the reputation for safety in the 80s was based on anecdotes not on statistics? Further, it had more to do with the drivers then the cars. Volvo appealed to a specific type of driver; who by correlation tended to be a defensive driver.
The result; Volvo had a sterling reputation for safety.
Fast forward a few decades, and the highway insurance group starts testing cars. Volvo does very poorly, to save sales, Volvo made significant changes to the car designs; and very quickly rose through the pack. The end result, Volvo now places near the top on many; but not safety tests.

When you look at aircraft accidents; due to regulations the differences between planes certified at the same revision which is recent (e.g. Mooney still uses a much older regulation); there is not a lot to differentiate between the models of aircraft. They all now have the 26G seats, stall prevention, cabin frames.... The real differences come down to only a coupe of items. Stall speed, pattern speed and most critically the pilots. Stall speed plays a factor in the energy required to dissipate; pattern speed is how the plane is normally flown, and its relation to stall speed. Pilots, kill more planes than they save; nothing has changed about this statistic in decades. You get fuel totalizers, pilots ignore them. You get stick shakers, pilots grab the stick harder, you add stall horns, pilots get noise canceling headsets...

I tend to believe, the simple answer is often more accurate then the nuanced and precisely rationed answer. Look at the pilots first, planes second.

Tim
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Re: DA40NG

Post by blsewardjr »

Assuming that they were produced in roughly the same numbers and have similar missions, I did a quick 10 year study of the NTSB database of the SR20 vs. the DA40-180. I excluded foreign accidents because the data base doesn't include all foreign accidents. Over that period there were 47 SR20 accidents/incidents in the United States (4.7 per year), of which 13 were fatal (28%). At the same time there were 23 DA40-180 accidents/incidents (2.3 per year) of which 5 were fatal (22%). This improved for the DA40-180 over the period. Since 2010, the DA40-180 has averaged 1.5 accidents a year (5 accidents a year for the SR20). There has been only one fatal DA40 accident since 2012 (5 fatal accidents for the SR20 during 2013-17).

As much as I like the comfort of the SR20, I chose the DA40 for its accident record and flying characteristics. My view is that the DA40's better safety record than the SR20 results from it's protected gas tanks (aluminum with spars on either side vs. wet wing), lower stall speeds (over 5kt difference), safer seats (seats and belts fixed to the airframe vs. seats that move and have seat belts that are not attached to the airframe), benign landing characteristics (vs. frequent pilot induced oscillation if too fast and/or forced on) and stick feedback when getting slow (vs. spring loaded constant feel at all airspeeds).
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Re: DA40NG

Post by TimS »

blsewardjr wrote:Assuming that they were produced in roughly the same numbers and have similar missions, I did a quick 10 year study of the NTSB database of the SR20 vs. the DA40-180. I excluded foreign accidents because the data base doesn't include all foreign accidents. Over that period there were 47 SR20 accidents/incidents in the United States (4.7 per year), of which 13 were fatal (28%). At the same time there were 23 DA40-180 accidents/incidents (2.3 per year) of which 5 were fatal (22%). This improved for the DA40-180 over the period. Since 2010, the DA40-180 has averaged 1.5 accidents a year (5 accidents a year for the SR20). There has been only one fatal DA40 accident since 2012 (5 fatal accidents for the SR20 during 2013-17).

As much as I like the comfort of the SR20, I chose the DA40 for its accident record and flying characteristics. My view is that the DA40's better safety record than the SR20 results from it's protected gas tanks (aluminum with spars on either side vs. wet wing), lower stall speeds (over 5kt difference), safer seats (seats and belts fixed to the airframe vs. seats that move and have seat belts that are not attached to the airframe), benign landing characteristics (vs. frequent pilot induced oscillation if too fast and/or forced on) and stick feedback when getting slow (vs. spring loaded constant feel at all airspeeds).
They were not produced in equal numbers. Also, look at the accidents, then look at the safety items you mentioned and see how they play in the accidents. Both have 26G seats, so unless the seats come out in the accident, how does this play?

Tim
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Re: DA40NG

Post by blsewardjr »

Tim- Admittedly, all these number are hard to quantify and contain certain assumptions (e.g., that SR20s and DA40s are flown approximately the same number of hours). Nonetheless, there are 712 N-registered DA40-180s in the U.S. versus 853 N-registered SR20s in the United States. In the absence of other numbers, I consider that roughly equal. As for the safety factors, take a look at the written reports of SR20 accidents and I think you'll see why I mentioned the factors I did.
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Re: DA40NG

Post by TimS »

@blsewardjr

After about twenty NTSB reports, I have come to the conclusion pilots kill planes.
The only factor you listed which may apply in the reports I did a quick review was stall speed.

However, I am glad you love your plane. I am looking forward to owning again.

Tim
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Re: DA40NG

Post by Antoine »

Thanks Bernie for a very thorough, fair and significant analysis.
I agree that pilot errors are by far the main cause, but consider this:

> same mistake (stall) will result in a nose dip (DA40-180) or in much worse (SR20 / DA40-NG). Do this in the pattern and welcome to NTSB. I openly admit that my DA40 saved my life once.

> It seems obvious to me that landing a DA40 with the center stick and "natural" aerodynamic feedback is easier and safer than doing it with a spring loaded side yoke that masks the aerodynamic feedback at very low speeds.

So yes, a pilot mistake is frequently (almost always) the cause, but some planes are much more tolerant by design and the DA40-180 is simply... perfect.

And I wonder why nobody is commenting upon the outrageous, almost criminal design mistake in the DA40-NG (engine master switch) and how this one got through internal processes and certification...
THIS is a big deal to me and the proof that something is very flawed in the certification rules.
DAI were lucky that the accidents did not happen in the US... The lawsuits would have made the DA42 saga look like a walk in the park...
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Re: DA40NG

Post by Tommy »

You are right on Antoine on every point. It is what it is.
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Re: DA40NG

Post by CFIDave »

Antoine wrote:And I wonder why nobody is commenting upon the outrageous, almost criminal design mistake in the DA40-NG (engine master switch)
I already brought up the issue of the originally-flawed NG switch design, and how it has been effectively fixed. All DA40 NGs are now delivered with a switch guard that completely eliminates any confusion between the Engine Master and Fuel Pumps switches. Go actually fly an NG and you'll see.

I really wish those of you who keep hating on the DA40 NG would go fly one. It wasn't until I flew one (instructing multiple pilots on full stalls holding the stick all the way back, instructing landings in the traffic pattern in very gusty x-wind conditions, flying long x-country flights, etc.) that I came to appreciate that the NG handles like a DA40 -- just a whole lot quieter and smoother.

BTW, in considering the higher NG stall speed, be also aware that the NG also lands better in crosswinds: the DA40 NG maximum demonstrated x-wind component is 25 knots (identical to all Diamond twins) rather than the 20 knots max x-wind of the Lycoming DA40-180.
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Re: DA40NG

Post by krellis »

CFIDave wrote:
Antoine wrote:And I wonder why nobody is commenting upon the outrageous, almost criminal design mistake in the DA40-NG (engine master switch)
I already brought up the issue of the originally-flawed NG switch design, and how it has been effectively fixed. All DA40 NGs are now delivered with a very effective switch guard that completely eliminates any confusion between the Engine Master and Fuel Pumps switches. Go actually fly an NG and you'll see.

I really wish those of you who keep hating on the DA40 NG would go fly one. It wasn't until I flew one (instructing multiple pilots on full stalls holding the stick all the way back, instructing landings in the traffic pattern in very gusty x-wind conditions, flying long x-country flights, etc.) that I came to appreciate that the NG handles like a DA40 -- just a whole lot quieter and smoother.

BTW, in considering the higher NG stall speed, be also aware that the NG also lands better in crosswinds: the DA40 NG maximum demonstrated x-wind component is 25 knots (identical to all Diamond twins) rather than the 20 knots max x-wind of the Lycoming DA40-180.
I'm not going to voice an opinion on the DA40-180 vs NG flying qualities/stall speed, etc. since I have not flown the NG, but I will weigh in on the crosswind limits just mentioned. Manufacturers list maximum demonstrated crosswind which is not necessarily a limitation. I recall from my Boeing Flight Test Engineer days that it was the strongest crosswind that we could find on the day of the test and show adequate control authority. So I would take the 20 versus 25 knot numbers with a grain of salt. Pilot skill and proficiency heavily weigh on this number as well.
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