DA42 Purchase

Any DA42 related topics.

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CFIDave
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Re: DA42 Purchase

Post by CFIDave »

An extra 10 knots of airspeed gained by running the engines harder only gets you to your destination 12 minutes earlier on a 4-hour flight. But because your miles-per-gallon is worse at higher power settings, it costs you more in fuel and also reduces your range.
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dgger
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Re: DA42 Purchase

Post by dgger »

neema wrote:The weird thing is that there is no incentive [...] for keeping power lower.
Range.

Range takes a big hit when you push those throttles. If your typical flight is short it may not matter, but going a tad slower might make the difference between doing a fuel stop or not. Or even just getting there, if we are talking about some flights over large bodies of water. Hell of an incentive...
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neema
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Re: DA42 Purchase

Post by neema »

I disagree. Range doesn't take a big hit with throttles pushed forward. There's a 1 (one) nmpg difference between 75 and 85%. A headwind could make a much more dramatic difference.
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Re: DA42 Purchase

Post by Johnmyers »

CFIDave wrote:An extra 10 knots of airspeed gained by running the engines harder only gets you to your destination 12 minutes earlier on a 4-hour flight. But because your miles-per-gallon is worse at higher power settings, it costs you more in fuel and also reduces your range.
But it costs you more in non-fuel hourly engine expenses to fly slower, so it would seem to be actually more expensive on balance to fly slower, no?
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Re: DA42 Purchase

Post by dgger »

Johnmyers wrote:But it costs you more in non-fuel hourly engine expenses to fly slower, so it would seem to be actually more expensive on balance to fly slower, no?
You are right. Depending on your fuel and maintenance cost (and schedule), you might save a few bucks. In my experience it is not a whole lot, though.
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Re: DA42 Purchase

Post by dgger »

neema wrote:I disagree. Range doesn't take a big hit with throttles pushed forward. There's a 1 (one) nmpg difference between 75 and 85%. A headwind could make a much more dramatic difference.
I guess everyones definition of „significant“ is different. My aircraft gives me the following air ranges at 10,000ft assuming a 10 USG reserve at destination.

50%: 1,005 NM
60%: 900 NM
70%: 845 NM
80%: 760 NM
92%: 680 NM

So, for me, I think that can make quite a difference - in particular, when you can avoid a fuel stop by going a tad slower.

Yes, a headwind can have a dramatic effect, but you dont usually get to pick your favourite headwind...
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neema
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Re: DA42 Purchase

Post by neema »

dgger wrote:
neema wrote:I disagree. Range doesn't take a big hit with throttles pushed forward. There's a 1 (one) nmpg difference between 75 and 85%. A headwind could make a much more dramatic difference.
I guess everyones definition of „significant“ is different. My aircraft gives me the following air ranges at 10,000ft assuming a 10 USG reserve at destination.

50%: 1,005 NM
60%: 900 NM
70%: 845 NM
80%: 760 NM
92%: 680 NM

So, for me, I think that can make quite a difference - in particular, when you can avoid a fuel stop by going a tad slower.

Yes, a headwind can have a dramatic effect, but you dont usually get to pick your favourite headwind...

Totally agree--avoiding fuel stops is a no brainier.

My observation was that there's no standout penalty for cruising a little faster. Legacy air-cooled mills may punish you with needing a top end OH (if temps not managed correctly). Not so on these engines.
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Re: DA42 Purchase

Post by neema »

Here's another (disappointing) data point for folks. This is from our 3rd annual on the plane @ 900 hours. Here are the main items:

Pitot heat failed. Wasn't the relays. No OH possible. Whole pitot tube replaced: $2512
LH prop governor leaking, have to send to MT Germany ($400 shipping) since they don't service FADEC prop governors in the US. They recommend the $400 more for OH rather than a reseal: $2500
4x engine mounts leaking fluid filling: $1370.
Battery failed cap check: $700
4x ECU backup batteries and 2x alternator excitation batteries: $830 (This is painful after I learned we could have spent $200 for the exact same batteries if we purchased ourselves)
RH alternator broke when disassembling for 300 hour check; can't OH. Replacement is $1300


Another $17-18k annual. Hope this is a helpful datapoint. In a couple hundred hours we're looking down the nose of the fuel injector AD ($12k) and the timing chain AD is inevitable
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Re: DA42 Purchase

Post by jb642DA »

Neema -
How many hours did you put on your plane last year?
The listed items are approx $9300 -
What makes up the other $8000+ for the annual? Thanks
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neema
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Re: DA42 Purchase

Post by neema »

We did 300 hours in the last year. Not an extreme amount of use, but definitely keeps the plane nice and busy. Probably 350 landings if I had to guess.

Other costs:
$4200 for the annual inspection itself
$1400 for the 100/200/300 hour service (oil change and 300 hour inspections)

The remainder is a handful of normal little squawks and findings from leaks, etc.
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