Double Fadec Failure

[Ananas]

Hy all,

yesterday I embarked on a "routine" circuit training flight as a FI on a C172 which was recently retrofitted with the Thielert Centurion 1.7 diesel engine.
The manufacturer of this engine (http://www.thielert.com/) says that "The FADEC system is a fully redundant 32-bit motor management system for the CENTURION 1.7 which includes safety appliances. .
In the amendments of the POH it says that if one Fadec fails the other takes over immediately.

Well, forget it
Yesterday I had a double instantaneous failure of the system.
Only untill a few seconds from the treshold I tought I was going to stick this C172 into town. If the engine failure had happened 50ft lower, we would have been evening news.

On our airfield there is a Diamond DA40 with the same engine, that had to return to the shop a month ago for "fluctuating engine power".

According to Thielert (and the amendments of the POH) the loss of 25HP between the 2 different engines doesn't affect T/O nor climb performance. Well, my experiences as an instructor says diferrent.

I am starting to think that this new technology isn't ripe yet and that the figures in the POH are pleced to help sales instead of pilots.

I would like to know who has experiences (bad or good) with these diesel engines.

[lszb]

Ananas,

give us some more information on the double failure please.

Also what information do you have about the DA40 problem, as it doesn't sound remotely connected to your incident.

The new advanced systems now available to light aircraft are excellent, but as with all new equipment will suffer from teething problems from time to time, just like the original Lycoming engine which suffered multiple failures when first operated.

Any outcome from your incident would be appreciated.

LSZB:ok:

[Ananas]

Well,

the DA40 had in its secondary oil system (gearbox and governor) metal scrapings that clogged the filter of that line up. This resulted in unstable pressure on the line and fluctuating RPM. It is a known problem on the Thielert engines. At our airport (EBAW) there are 5 planes with that engine, and this was discovered on 3 out of 5 (including the one I flew on Monday 26th).

I felt this erratic RPM in the first seconds of the problem. But soon both Fadec warning lights illuminated simultaneously and the engine stopped. Battery and engine master switch were both ON, so the student didn't shut off the engine by accident.

Now, the engine works only on 1 Fadec at the time. If it gets wrong information from one of its sensors (from the governor in this case) it might not work correctly.
Worst case scenario, it may fail. But the system then should switch automaticly to the other Fadec (according to POH:rolleyes: ). If it doesn't, there is a switch that forces it to use the other one.
In this case I couldn't, because both Fadec failure light were already flashing.

I didn't try any other troubleshooting because I was with a dead engine at 800ft and still had, what seemed at the moment like a million miles to cover to the threshold, and was approaching on a 90° track on the QFU.

Tell me Iszb, have you flown those diesel engines?

Oh yeah,

last minute info.

The mechanics changed the clogged oil filter and resetted the Fadec\'s, and signed off the plane.

It seems they are not intrested to try and know why there is metail in the oil, nor why the Fadecs failed.:mad: :mad: :mad:

[GJB]

Are you claiming that due to the clogged secondary lube system, FADEC failed and the engine shut itself down?

[Ananas]

No GJB,

that is not possible, as far as I can read the tech drawings.
Even if there is wrong data coming from that system, the Fadecs should not (COULD NOT) shut down.
I am not saying that there were problems with the sec. oil system. Just that it has happened to other planes and on my plane they found metal rests in the filter. Was there already enough metal to start a problem, nobody will tell. It is just the mechanic that declares this (but I don't buy it).

The sure thing is that both Fadecs quit working, and that it is not the first time it happened. A few months ago another of our instructors had something similar, but it was brushed under the carpet. They told it to nobody.:mad:

[booke23]

I have flown the above aircraft/engine combo a few times now, and at first I was mighty impressed.

In particular I liked the fact that the turbo charged engine produces almost the same power at 10,000ft as at sea level.......so excellent climb performance at altitude......compared to say a PA28-181 which starts to seriously run out of puff above 5,000ft. Additionally fuel burn was phenomonal.....3-4 gals an hour....and the fuels a third the price of avgas.

I also liked the fact that carb ice no longer had to be worried about...nor did mixture.....significant reduction in cruise workload.

However I do think the engine instalation is a bit green. On the fleet I flew, there has been numerous problems relating to the engine fit. Some electrical.........some to do with the gearbox/clutch. No forced landings but an engine stopped while taxing due to total electrical failure.

So I have decided to no longer fly the diesel's any more. There have been no forced landings due to sheer luck (gearbox glitch almost resulted in a forced landing, but it held together for a return to the airfield). If the engine lets go at 300ft on the climbout someones going to get hurt (overshoot is far from ideal). I believe vibration has caused alot of the electrical problems, not surprising considering the complexity of the fadec systems (large wiring looms going to/from engine bay).

I hope all the problems can be ironed out, I believe aero diesel has the potental to revolutionise and significantly reduce the cost of GA flying in the UK. I will go back to diesel if they manage to make the setup as reliable as the old lycoming fit.

[owwnav]

I was interested to hear your experience, and was glad that you made it safely back to the airfield. I am familiar with the Thielert engine as I fly an aircraft which was converted to one. What I was wondering was have you learned anymore about what caused the double FADEC failure? I know that when there is any engine event, that a download has to be performed and sent to Thielert. From this they are normally able to indicate what took place during the event. Was this done with your aircraft and if so what was the cause of the failure. If wasn't done I would be very surprised, as the data will show up at the next scheduled maintenance download. The other thing I was wondering was how much of an RPM fluctuation took place and how long it lasted before the engine shut down?
We have over 200hrs flown on the new engine and while it has not been without its glitches, overall we have been very happy with its performance. The FADEC's have given us warning of any deterioration in the engine operation and the engine always continued to running. I would be very interested to know of anything else you have learned about the shutdown since your last post.

[yachtno1]

Would both FADEC fail lights come on if the engine stalls? :)