Which engine for DA-40

[BARThompson]

All,

I am looking to buy a DA-40. However, due to cost, I am likely to get a second hand one but there are several different engines available. As far as I can tell, there is the 180hp Lycoming engine, the Thielert engine or Diamond's own Austro engine.

I will be flying the aircraft in the UK and Europe and therefore efficiency is a big benefit on the cost front. Other considerations are operating altitude - do the diesel's (being turbocharged) mean a higher achievable altitude.

But what about availability and maintenance? There seem to be more lycoming engines available. Having never owned a diesel, I dont know if they cost more/less to maintain.

Any thoughts/opinions welcome.

Many thanks

[cockney steve]

You may care to start by doing a thorough Googoo search on all things Thielert.

AIUI, there were problems with very short-lifed reduction-gearboxes and ISTR a clutch problem as well.
Weight, vibration and , to a lesser extent, noise, are also issues. cold operations can also be difficult with Diesels, though Ibelieve the Thielert ran on Kero/ jet and not Derv. (so no waxing issues) The fact they went bump quite spectacularly, ,left a lot of temporarily grounded aircraft...Iassume the Lycosaurus was a modification, retro-replacement, which wouldn't have been cheap.
The Austro engine is an unknown quantity to me, It seems to be ticking along in the background, whereas there was a lot of razzmatazz surrounding the Thielert which, if it had been properly sorted, would surely have been a front runner today.

Rotax were virtually unknown 25 years ago....you had a choice , in a Flexwing, of a Robin, or a Rotax...(when do you hear of Robin today?)

Do a lot of research ,first.

[soay]

Lycomings are faster, with a better rate of climb and cheaper to maintain, but cost more per hour in fuel.

Thielert engines have to be replaced rather than overhauled at end of life. They also have expensive components which have to be inspected and overhauled or replaced every 300 or 600 hours.

Thielerts were notoriously unreliable, but the causes have been dealt with, so should now be on a par with the Lycomings for reliability. Thielert/Centurion have recently been bought out by a Chinese company, so are unlikely to go bust again.

Turbocharging allows the Thielerts to operate at higher altitudes, but lack of deicing and built-in oxygen reduces the opportunities to take advantage of that.

The G1000 software in the Thielerts hasn't been updated for 6 years, whereas Lycomings are more up to date.

The Austros are 50kg heavier, which increases stall speeds by 11 kts.

This from someone who has a DA40TDI.

[smarthawke]

The Lycoming IO-360 was the original engine in the DA-40 - the Thielert option arrived later.

[soay]

Really? If 50kg makes 11kts difference to the stall speed there must be about 50Kts difference between the stall speed flying solo vs 4 up! I don't think so.
Seeing is believing:

DA40 TDI AFM (http://www.diamond-air.at/fileadmin/uploads/files/after_sales_support/DA40-TDI/Airplane_Flight_Manual/Basic_Manual/60105e-r7-DA40-D-AFM-complete.pdf)

DA40 NG AFM (http://www.diamond-air.at/fileadmin/uploads/files/after_sales_support/DA40%20New%20Generation/Airplane_Flight_Manual/Basic_Manual/60115e-DA40-NG-AFM-r2-complete.pdf)

In section 5.3.5, you'll see that in the landing configuration at max weight, the stall speed has gone up from 49 to 60 kts.

[Big Pistons Forever]

I have not flown either model, but a good friend who has flown both the Diesel and the Lycoming powered DA 40's reported that he found the diesel (1.7) very under powered.

[A and C]

The only way to go in Europe is diesel, Cockney Steve's comments are largely out of date, the issues that caused Thielert to go bust are now well understood and effectively over.

Gearbox and clutch life have increased and are not expensive to change with the unit being exchanged at the service life intervals. The 1.7 engine is no longer avalble ( but supported) so at life you have to fit the much more reliable 2.0 engine.

The Austro engine a bit of an overkill following the Thielert problems and so has a much increased weight and power however these balance each other out and the performance is much the same.

I would look for a DA40 with the 2.0 Theilert engine and a maintenance company that understands the engine as well as composite structure....... Finding a company that understands composite structure in the UK is the biggest ask !

[YODI]

I love the Da40 Tdi, it's my favourite SEP aircraft by far, yes they can be expensive during maintenance costs but they are a mere 19L per hour (approx) of Jet A1

I have maintained the DA40's with Thielert for over 6 years, I also fly them. If you are going to put some serious hours in every year the economy takes effect. In short, if you are not going to do say 300+ hours a year then the Tdi is definitely not the correct engine choice for you.

I'm not sure I understand the comment above about the G1000 in the TDi not getting updated, they get the latest software every annual as the Avgas equivalent does.

I have had a DA40 up at FL160 for 3+ hours and was pleasantly surprised how well it handled it, and if you get one with Autopilot they are great too.

If I can be of any help let me know.

Yodi

[soay]

I'm not sure I understand the comment above about the G1000 in the TDi not getting updated, they get the latest software every annual as the Avgas equivalent does.
If you look at the G1000 on a DA40 TDI, you'll find many software features that have been released in the past 6 years, such as flight logging, wind vector options, vertical navigation, IAP minimums and synthetic vision are not available. Diamond have stated that the only way to get them is to upgrade the aircraft to an NG. That's a pretty shoddy way to treat their customers, in my opinion.

There must be other differences than just the weight of the engine, I wonder what they are?
I guess the fact that most of the weight increase is in the nose can't help. They also changed the winglets to reduce drag and that may have reduced lift at lower speeds.

[Mearns Loon]

There were approx. six DA40-180 sold in the UK when they were first brought out. All the later ones were diesel engined. So there should be more diesel engine variants in the UK.

[Skeeve]

Meldex (and Soay),

airspeed calibration. Don't compare apples with oranges. Figure out the stalling speed in CAS, then compare.

If you read section 5 close enough you will notice a different airspeed calibration between those two models.
Especially in the low speed.

Actual stalling speeds in CAS:
DA40D: 54kt (1150kg)
DA40NG: 58kt (1280kg)
DA40NG: 55kt (1150kg)

So basically, its a wash.

[soay]

I agree with your CAS for the DA40D at VS0 of 54kt (at 1150kg), but I make it 57kt for the NG. (As its graph of IAS vs CAS starts at 65kt, I've assumed the same +1kt discrepancy at 58kt, which is its VS0 at the same mass.)

Also, as the basic mass of the NG includes an extra 50kg for the engine, plus beefing up of the undercarriage to support it, the takeoff mass is going to be greater for any given load, hence VS0 will be even higher.

So, not quite a wrap.