Antoine wrote:Does anyone know of fatal accidents caused by stall/spin in a DA40-180?
There was one likely stall-spin in a DA40F in 2016 (Utah), and the crash in Peru in 2013 is also a likely stall-spin. That's it in the NTSB database that I've seen, in over 15 years of production.
In all fairness the examples in Utah and Peru are speculative. By some reports the college student in Utah was goofing off and the gentlemen in Peru were operating near the 40s certified altitude, remember that the crash site alone was at 14,500 ft. A disturbance stage of hypoxia and impact with high tension power lines were also contributing in the Peru accident. It's noteworthy I believe that flying behind an AE300 may have mitigated the latter accident altogether, who knows (shrug).
Boatguy54 wrote:As the OP, this turned into a much more lively discussion than I expected! And you are all to be applauded for the civility in the face of significantly different opinions, something sometimes lacking in other discussion forums.
What is missing is comments from owners of the DA40NG. Maybe the lack of comments speaks to how few there are, or perhaps they are out flying or don't watch the public side of the forums. Maybe Dave can prod some of his customers into making some comments?
Dave seems to be the only commenter who has even flown the plane, the other comments all seem to be speculation based on POH performance data. Colin has the Austro engines in his DA42 and as far as I can tell he likes them, particularly the smooth and quiet operation.
Here is how I sum up the comments thus far:
Pro
- simplified engine management for pilot
- increased engine reliability (subject to debate about data)
- smoother and quieter operation
- lower cost of operation
- improved high altitude performance
Con
- heavier empty weight
- reduced SL and lower altitude climb performance
- increased stall speeds (though less of a difference at steep bank angles)
I'm not trying to make a case one way or the other, just trying to summarize what I'm reading.
Thank you.
I hope the Austro engine continues to evolve and have commercial success. It certainly is smooth and easy to manage. But, I don't think one can rationally argue that it is more reliable - if reliability means it doesn't quit in flight. There may be more 40NG's coming in the future, but as of now, there are 23 registered DA40NG's in the United States. Of those 23, there have been 2 documented engine failures that led to crashes. There have also been a number of Austro engine shutdowns in DA42's experienced by members on this forum. On the other hand, there are over 700 Lycoming DA40's registered in the United States with likely well over a million fleet hours and I don't see any evidence that the Lycoming's quit. I don't see a debate in that data. It is what it is.
As far as operating cost, there is no doubt that the fuel cost of the NG will be less, but I'm not sure the lifecycle cost of the Austro engine would put the 40NG in the pro column for operating costs. There are a number of expensive inspections and component replacements, I believe at 300 or 600 hour intervals. I've heard grumblings that the hourly engine cost over the 1800 hour life of an Austro engine is nearly $50 per hour. If so, that would far exceed the lifecycle cost of the Lycoming IO-360 M1A. Perhaps someone with more detailed knowledge can comment on that.
In Europe we have the situation that Avgas is now in the region of USD 3,-/Liter. Jetfuel is approx. half. So with the Austro you save a lot in fuel with the lower consumption and the lower price. However, all of this money goes into higher maintenance cost and probably can’t even compensate. We have a DA40NG in our flying club and we have our DA42NG, so I have first hand experience. So the advantage that remains is the better availability of Jetfuel, which makes life a lot easier here and in many parts of the world. Maybe also the advantage that in a crash with Jetfuel you have a much better chance of no fire.
No real data; and backed up by OWT.
Simplicity does mean reliability. What is more reliable a Lycoming IO-540, a PT6-121A, or RR Trent?
You will notice I went up in complexity, and also in reliability.
Auto-engine testing puts aviation engine testing to shame. No aviation piston engine could pass those tests. Auto companies have tiny margins, so they test the beejezus out of the engines to save money on claims.
However, Lycoming and Continental are the devil we know. The result is we often overlook the issues and shortcomings of these engines.
shorton wrote:As far as operating cost, there is no doubt that the fuel cost of the NG will be less, but I'm not sure the lifecycle cost of the Austro engine would put the 40NG in the pro column for operating costs. There are a number of expensive inspections and component replacements, I believe at 300 or 600 hour intervals. I've heard grumblings that the hourly engine cost over the 1800 hour life of an Austro engine is nearly $50 per hour. If so, that would far exceed the lifecycle cost of the Lycoming IO-360 M1A. Perhaps someone with more detailed knowledge can comment on that.
There's an article "Diesel Reset: Improved Economics" in the August 2016 issue of Aviation Consumer by well-respected journalist Paul Bertorelli that directly compares total hourly cost (including engine reserve for TBO/TBR, required maintenance, and fuel cost) of Thielert/Continental diesels, Austro diesels, and the Lycoming IO-360.
The Austro had the lowest cost of operation per hour in the US -- where avgas is relatively cheap:
Continental CD135: $47.70
Continental CD155: $51.01
Austro AE300: $39.28 <--used by DA40 NG
Lycoming IO-360: $55.10
The Austro had an even bigger advantage in Europe with expensive avgas:
Continental CD135: $55.71
Continental CD155: $58.88
Austro AE300: $42.84
Lycoming IO-360: $89.50
And don't forget that Austro engines only require service (including oil changes) every 100 hours instead of every 50 for a Lycoming, which means half as many trips to the shop unless you do your own oil changes. And during each Austro 100 hour oil change interval, it's normal for an owner to have to add only about 1 liter or quart of oil. In contrast, even with 50 hour oil change intervals, owners must add more oil to Lycoming engines much more frequently.
Epic Aircraft E1000 GX
Former DA40XLS, DA42-VI, and DA62 owner
ATP, CFI, CFI-I, MEI
Just as a theoretical exercise I ran the W&B numbers on a flight I took last year from Spokane to Prineville for both my plane and a sample NG. Basically, myself, my stepdaughter, her two girls (10-13 yrs. old), full fuel and pretty much all the baggage I could stuff in the plane in the baggage compartment and rear seats.
I used the actual weight of my plane and the W&B for the DA40-180, against the sample airplane (which might not reflect any specific actual airplane) in the NG manual and its W&B calculations and limitations:
My plane calcs came out to 2,571.40 lb., CG 100.39 in.: 74.6 lb. under gross, 1.61 in. forward of rear CG limit.
The sample NG came out to be 2884.4 lb., CG 99.90 in: 10.61 lb. under gross, .30 in. aft of rear CG limit. Now this was using 7.01 lb./gal as fuel density, as it has in the manual. So I tried it at 6.7 lb./gal fuel density, an oft-quoted density for Jet-A. This came out to be a bit better at 2,865.3 lb. and 99.88 in. CG. But CG is still out of aft limit by .28 in.
My plane is a bit unusual, being one of the lighter, earlier ones with standard tanks, extended baggage and MTOW mod done. For this flight the front seats totaled 340 lb., rear seats (including various stuff the kids had there) totaled 200 lbs. and 100 lbs. in Forward baggage.
Obviously there is uncertainty around a couple of the numbers used for the NG. One of which is Jet-A fuel density. Poking around one can find various values for this fuel. But this exercise does show that it's pretty easy to bump up close to, if not beyond the rearward CG limit in the NG if you utilize extended baggage. It's the most restrictive in rearward loading of the DA40 variants. I can tell you I've stuffed this area full quite a few times over the years.
Rich:
Because of the greater weight of the Austro engine, the NG tends to be more nose-heavy than other DA40s, which allows for better use of the back seat and rear baggage area than typical tail-heavy DA40 XLS aircraft. Early "steam gauge" DA40-180s (without a G1000 equipment rack located under the rear baggage compartment), are light and tend to be nose-heavy.
I've always used 6.7 lbs/gal for JetA in my calculations. JetA weighs 804 kg per cubic meter at 15degC standard temperature, which works out to 6.7 lbs/gal.
Epic Aircraft E1000 GX
Former DA40XLS, DA42-VI, and DA62 owner
ATP, CFI, CFI-I, MEI
CFIDave wrote:Rich:
Because of the greater weight of the Austro engine, the NG tends to be more nose-heavy than other DA40s, which allows for better use of the back seat and rear baggage area than typical tail-heavy DA40 XLS aircraft. Early "steam gauge" DA40-180s (without a G1000 equipment rack located under the rear baggage compartment), are light and tend to be nose-heavy.
I've always used 6.7 lbs/gal for JetA in my calculations. JetA weighs 804 kg per cubic meter at 15degC standard temperature, which works out to 6.7 lbs/gal.
All I can say is I used the empty weight and moment of the sample airplane (1984 lb., 189,253.76 in-lb.). And yes, as I stated I compared it to my plane which absolutely has a forward empty CG relative to the latter models. Even given that, the sample NG empty weight is about 3.5 inches forward of mine. And lo and behold, the loaded NG CG is forward of mine, by .49 inches
BUT
The aft limit of the NG is the most limited of all the variants, at 99.6 inches. Mine is 102 and even the long-range tanks (greatly and often complained about) on the other Diamonds are at 100.4. With the forward limit of all at 94.5 inches, the range to hitting the aft CG's are:
40 gal gas and standard TDI: 7.5 inches
Long Range tanks (TDI and gas): 5.9 inches
NG: 5.12 inches
It'd be useful to get a couple of ACTUAL empty weight/moments of real XLS's and NG's rather than the sample airplanes in the POH. (I constructed a NG W&B spreadsheet just because I have too much time on my hands.) The base DA40 manual shows a 1620 lb. airplane. There is no way any actual DA40 sold to a customer was this light.
FWIW before we accepted delivery of our DA40 we required the actual values from Diamond.
Dave's (and presumably others) perspective is comparing Diamond's current new-plane offerings (XLS vs. NG). That makes sense. Mine might be about the best weight hauler overall anywhere in the fleet, so perhaps unfair.
