sternone

Jut make sure you get 2.0 Thielert diesels with it, i just read the december article in aviation consumer and diamond says they had 22 in flight stoppages of the 1,7 diesels !!! 22 ? Blimey!!

Three Yellows

sternone,
I would have thought that you would have learnt your lesson regarding posting opinions on technical issues after the PA28 'incident'.

hobbit1983

Sternone - do you have a link to that article? (genuinely curious!)

englishal

I had one once...but that was because I turned the engine master off

BackPacker

My club can vouch for two inflight stoppages of 1.7 Thielerts. Well, in both cases not in-flight stoppages but severe loss of power leading to forced landings. Both with good outcomes, fortunately.

Having said that, one of the inflight problems was an almost full loss of power and the incident was fairly recent. I do not know if the cause was already determined and what the cause actually was, but the issue was sufficiently complex that this aircraft (a Robin DR200-135 CDI Ecoflyer) had to spend a week or two in the field where it landed. (And for those who are not familiar with the type - the Robin has wooden spars and are normally hangared. Yes, the aircraft was thoroughly inspected before being brought back into service.)

The other incident involved a Diamond DA-40 TDI with the 1.7 engine, and was traced back to a damaged ECU Auto/B switch, leading to perpetual FADEC resets and eventually an undocumented (as in "not in the POH but in the maintenance manual") "failsafe" mode where you have 0% or 100% power, but nothing in between. As all Diamond owners will know, this ECU Auto/B switch is dangerously close to the "flightpath" of your feet when entering/exiting the aircraft. All our switches now have guards on them to prevent further similar problems.

So in at least one case, the cause was not the 1.7 engine itself but to faulty input to the FADECs. I doubt whether the 2.0 engine would have less problems with that. I mean, we all know that intelligence is normally inversely related to cubic inches, do we?

What worried me more when reading about the DA-42 is the fact that a sufficiently charged battery is absolutely essential when retracting the gear. The alternator(s) cannot, on their own, supply sufficient current for the gear motors, leading to a loss of voltage which in turn leads to all four FADECs packing in. Long thread about this about a month or two ago. If you ever need to use external power to start, read the POH!

FatFrank

Heard in the pub on Friday (yes, in the pub so you need to take it as that) that there had been problems with low voltage (power) on the battery causing the system to reset in flight that causes the prop to feather fully.

Please this is what I heard not a definative fact so don't shoot

camlobe

Had a flight on Friday to France in a DA40 with the modified Mercedes 1.7 litre turbodiesel. Quiet. Economic at 5 gallons per hour. Back seat comfy for two hours. 110 kts @ 70%. Screaming engine, almost Rotax-like with the tacho reading prop rpm (lower figure doesn't upset the older aviating generation). Didn't really notice it go into auto-rough over the Channel. Not bad at all, really.

In the DA 42, as I understand it, the engine ECU's have had their back-up batteries enlarged as well as software changes following the previously mentioned incident.

Now picture yourself...

At point of no return in the middle of the Atlantic, your Lo-Volts light comes on. The alternators will not reset. You have battery power alone. At least 3 1/2 hours to landfall. Battery will last about 1/2 hour.

In a Beech/Cessna/Piper etc, you loose all electrics...But the engines will run until the fuel tanks are dry.

In a DA42, what would be the limiting factor, fuel or battery life? How long will the batteries last? Will you be subject to double engine auto-feather for protective purposes after one hour or so, handing you a low-drag and rather expensive and usless glider?

A number of people, myself included, are interested in knowing the true answer to this, not the rumours or pub gossip. (No offence to the gossiping pub rumour networkers)

P.S. How did it get certified in the first place? Was the certification
department of EASA manned purely by graduates with no real-world experience?

camlobe

soay

Thielert Diesel Reliability. Worth spending $12.95, if you really are interested.

Fuji Abound

Did you read the whole article?

Whatever your personal view your quote misrepresents the article - neither fair to the authors or Diamond.

Significantly the authors conclude:

That they dont know whether the "failure" rate of Thielerts is higher or lower than Continentals or Lycomings - because the data does not exist. Moreover Diamond suggest they do have the data and reliability is better.


Clearly the battery - with no battery power the FADECs will fail and so will the engines. A conventional system has two fuel pumps - if they both fail so will the engine. The DA42 has two alternators, in addition to the main and backup battery - if all fail so will the engines. That might be a good reason for not flying the aircraft out of sight of land for more than three hours but that is hardly a typical mission. Moreover the reliance would seem less dependant on the redundancy of the systems than a traditional engine on just two fuel pumps.

DX Wombat

There has been a mandatory modification to prevent this happening again. The shutdown was ENTIRELY pilot induced - they didn't follow the POH. Not in the one I fly! I'm amazed you can hit the ECU switch on entering or exiting, I certainly couldn't.

IO540

Sadly, the spread of publicity re engine issues with Thielert is limited only by the fact that most owners prefer to apply quiet pressure on their dealer before washing their dirty laundry in public which would just ensure they get cut off from any co-operation.

That's how aviation works... and don't I know it.

Everybody I have spoken to who owns a Diamond says the same things, more or less. Great aircraft, mediocre finish (metal fittings rusting immediately, etc), dreadful dealer support.

Such a shame, because there is nothing else out there that is modern. The avtur engine removes a whole lot of Euro touring issues in one go, too.

englishal

I'd trust a DA42 over a "conventional" twin any day. I can list many many reasons to go with a DA42.

I've not seen this bad finish mentioned? I've flown Diamonds for the past couple of years now, and they still look good as when I first flew them. Mind you maybe this is a difference between Canadian built ones and European ones? In fact one of the last ones I saw had full leather interior plus all the options

Let me know if you plan to base one at Bournemouth and I'd be delighted to talk

Cheers

IO540

The corrosion issues appear to be internal. Mostly not important stuff.

I am sure they will learn.

hobbit1983

soay - thanks for the link. EnglishAl- again also out of curiosity, what would your reasons to go with the Da-42?

englishal

1) situational awareness. G1000 makes it virtually impossible to fly into a mountain as my mate did in a steam gauge drived Seneca 2
2) FADEC - engine mismanagement by the pilot is extinct. How many people have overboosted a turbo or cracked a cylinderhead by mismanagement?
3) Build - Composite structure, tough UC. The wheels can be put down at Vne, meaning you can slam the throttles shut, drop the gear, pitch 30 deg down and come down like a bat out of hell if the s*it hits the fan. Try that in a seneca and a) your wheels will fall off, b) the engines will die.
4) Fuel burn - 6 USG jet A1 per hour per side at 150kts TAS
5) Stick - I prefer it
6) Turbos, managed by FADEC. Great for altitude.
7) Looks cool, especially with the "Ice" lights on
8) lovely to fly, good performance even with 4 adults and full fuel in a hot climate.
9) Not too much of a handful like some twins.

To name but a few....

BackPacker

I'm glad there's been a mandatory mod with regards to the gear retraction issue. Yes, the pilots did not follow the POH but in the thread mentioned we've established that virtually no single-engine POH (including the DA-40) mentions anything about an external power start, and on twin-engined aircraft the exact way on which you start the engines doesn't really matter. Plus, would you intuitively expect two engines to go into auto-feather mode just because you retracted the gear? Both if you come from a DA-40 background, and if you come from a "traditional" piston twin background, this was a completely unexpected failure. That's what scares me: it was a complete novel failure chain-of-events.

DX, where is the switch located then on the DA-40 you fly? In ours, it is on the extreme lefthand side of the panel, about 10-15 cm above the door sill, completely exposed to feet, flight bags and everything when the canopy is open. At least, the thinking in our club is that that is exactly what happened: somebody bumped into this switch and did not report it. As said, we subsequently had guards added to all switches located there to prevent further similar incidents.

The failsafe mode, as related to me, by the way, is very interesting. If the FADECs reset themselves too often within a particular timeframe they fall back to some sort of auto failsafe mode. Pull the power lever all the way back and you get 0% power. Nudge it forward, even if just a little, you get 100% power, or at least something close to that, assuming ISA conditions. I think in this mode the FADECs don't even trust their OAT and MAP sensors anymore so they pick a power setting that works sort-of optimal without damaging the engine, regardless of OAT, MAP and so forth.

This failsafe mode is NOT described in the POH! After a long hunt, the gent from our club who had to make a forced landing because of this, found it in the maintenance manual, of all places. Not something your average pilot has access to, particularly not in-flight.

BackPacker

Me too. But I have found that in the DA-40 the stick is located so far into your crotch (halfway up your thigh) that it is impossible to use a traditional kneeboard. You need to use a loose A5 clipboard and jam it in between your hip and the centre console instead. No other place to put plogs, maps and such except for the map pocket near your knee or on the coaming.

I've only flown VFR but I can imagine that especially for IFR flying you need to think seriously about where you're going to locate all your stuff to have it to hand, and visible, even if you need two hands to fly the plane.

With a yoke, you can either clip things to the yoke or use a kneeboard. Don't expect any of these solutions to work in the DA-40, or the DA-42, assuming the stick location is the same.

Having said that, if you can make the G1000 sing and dance for you, including things like displaying approach plates superimposed on a moving map, who needs paper maps, clipboards and such anyway?

DX Wombat

BackPacker, it sounds as if the switch is in approximately the same place, 30cms or so up from the base of the panel and immediately above the ECU power check button - but in that case I would have expected the HSI switch to the left of it to be hit rather than the ECU Swap. I'm amazed that anyone managed to hit it. From what I remember being told, the problem with the DA42 was that there is (or was - I'm not sure what the modification is) NO back-up electrical power available unlike the DA40 which has approx 30 mins available.
All this just serves to demonstrate the importance of actually reading the POH and not just making assumptions that because you have flown something similar (2 wings, 2 engines, retractable gear etc) that everything will be exactly the same. I was very fortunate in that my conversion to the DA40 was done by the CFI who laid great stress on the importance of reading the POH, especially before a new aircraft was flown.
The POH for the C152 does.

englishal

I too thought that not being able to use an A4 clipboard and not having a yoke clip would be a problem. But no...I use an A5 clipboard strapped to my leg which is fine for holding approach plates, A5 plogs, pen, paper, timer, whatever...Not that you need all that rubbish Load the approach into the G1000, reference the approach plate, start the timer soft key and you're all set .....

soay

I've found this A5 kneeboard works well for me. It has a stretch velcro band to wrap around your thigh, to keep it in place.

Zuluworks do one specially designed for the DA40, but the shipping costs three times as much as the board!