FADEC in GA - reliable?

[Mariner9]

Technical conversation with the Meridian rep at Aerofair about the installation of the Thielert Diesel into a PA28, as follows:

Me: How do you stop the engine without a mixture cut lever?"

Salesman "Simple, just turn the key off like in a car".

Me: "So what happens if the electrics fail...does the engine just stop then?"

Salesman: "err, good question...I'll go & get the Thielert rep"

German Thielert rep: "Yez, vot is ze question?"

Me "What happens to the FADEC if you get electric failure?"

Thielert Rep: "Zat cannot happen - aircraft electric systems are very reliable"

Me: "Not in a 18 year old PA28 they aren't! So what will happen?"

Thielert rep "Wot can happen to electrics?...zey cannot fail!"

etc etc. Eventually admitted engine would stop without electrics. Seemed to me to be potentially unsafe. But then I realised that I haven't actually experienced a total electrical failure yet (touch wood)

Still, while FADEC may be suitable for airliners with multiple generator systems, alternate busses etc, it seems to me that further development is required before safe introduction into GA.

Any comments anyone?

[QDMQDMQDM]

Still, while FADEC may be suitable for airliners with multiple generator systems, alternate busses etc, it seems to me that further development is required before safe introduction into GA.

Too right. If you are introducing a new potential point of failure you'd better make bloody sure it doesn't fail! Relying on existing GA aircraft electrical systems does not seem the way to do it.

QDM

[FlyingForFun]

Never flown anything with FADEC. My instructor has - she did a license revalidation flight with someone whose aircraft had FADEC. She liked it - but then one flight doesn't really give you a very good idea, especially with regards to emergencies.

The Europa I fly also relies on electrics. Not quite to the extent that the engines you're looking at do - all it needs electrics for is the fuel pump. It has two electric pumps, one of which is connected directly to the battery, and the other is connected directly to the alternator. The idea is that whatever goes wrong with the electrics, at least one of the fuel pumps will continue to get power.

There are only two scenarios I can think of with this setup which could cause a problem. The first is avoidable - that's the scenario where the alternator fails, the pilot fails to notice it, and in time the battery goes flat. The second scenario is an electrical fire which results in the pilot having to shut down all the electrics. With enough height, it would be possible to pull all the circuit breakers except the fuel pump(s) and then turn the master switch back on, but more realistically you're going to be doing an engine-out forced landing with smoke in the cockpit. Scary - but we take risks every time we fly, and the increase in the risk is small enough for me to not worry about it.

FFF
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[topcat450]

I maybe giving Thielert too much credit here, but I doubt they would be relying on 20+ year old electrics. (but stranger things have happened :rolleyes: )

I imagine part of the installation kit would sort the electrics. Two independant FADEC systems, independantly powered on different circuits would be the minimum I'd expect, and well...at the end of the day...you can't cover every eventuality.

You can have 2 redundant systems, 3 or 4...and eventually if you fly long enough fate will gang-up against you and fail 'em all at once - in short - I'd not let it put me off getting one. :ok:

[CessnaEng]

Actually having done the Thielert course with the Thielert engineer you spoke to I can tell you that the FADEC is two channel with its own harness which is fitted at the time of conversion.

Now all we need is for Meridian to gettheir fingers out and start actually doing something.

[BEagle]

Perhaps a dedicated FADEC emergency battery should also be fitted for the unlikely event of aircraft electrics failure?

No electrics = no engine is simply not acceptable!

[NinjaBill]

Remember,t that this increase in risk has to be offset by the fact that diesel engines are inherently more reliable than petrol.

No spark plus to fail, no carb to ice up (although a throttle, but less change due to no evaporation taking place) less chance of overheating, lower change of fire, no explosive vapours when refueling......

If we are to make sweeping statements about these engines being 'unsafe' I think that it could easily be argued that traditional engines are also 'unsafe'

Any chance of a highly informed comment from Ghengis on this subject?

NB

[Sensible]

Is there an "affordable" pfa aircraft around with a diesel engine yet?

[A and C]

most FADEC s have a small generator to keep the system working if the aircraft electrics fail.

Pilots training on the NG737 are not even told about the one that is fitted to the CFM 56 FADEC , I suspect that a modern engine would such a system and the makers would not bother to tell you pilots about it !!!!!.

[Flight Safety]

Beagle, isn't that why they put mags on recips back in the good ol' days, so the engine(s) would still run with a total electric loss? What would the FADEC equivalent be today?

[Andrew M]

What about choppers that have FADEC systems in them - I'm sure according to A Chopper Is Born (Discovery Channel UK, with Mark Evans) that FADEC systems - both Choppers and FWing - have a back up system.

Mariner9 -

Me: How do you stop the engine without a mixture cut lever?"

It is not like this in the DA42. Check page 17 of FLYER magazine, the top right hand picture shows the power levers, and 2 knobs for cross feeding and cut off.

PMessage me and I'll email you the picture as a JPEG.

Happy flying,
Andrew M

[topcat450]

Sensible,

I don't know of any pfa types with a diesel....yet.....check again in a month or two and I may know of one. :ok:

[Lowtimer]

A customer Thorp 211 has now flown with the Wilksch 120 engine, according to a story on the Flyer site.

[big pistons forever]

I can't believe this discussion:). Existing engine technology is so old even a lawnmower would be embarrassed:rolleyes: Lets see instead of the typical turbocharged flat engine dance of throttle, prop, mixture, cowl flap, airspeed, while obsessing about EGT, CHT, and fuel flow; you get one lever and " pilot management "
means push to go and pull to whoa. Oh yeah and to start it turn the key, just like a flat engine except when it is cold, hot or somewhere inbetween.:ugh: I have over 4000 hours behind or beside GA piston engines from the C65 to the GTSIO 520 and I for one think the advantage of FADEC type technology is long overdue. Oh and by the way I once had a total engine failure ( in a single ) due to a failure of the oil pump, yet I have never landed in a aircraft that was electrically dead, so BRING ON the FADEC :ok:

[IO540-C4D5D]

big pistons forever

I agree with you 100% but (as someone who has been developing industrial electronic products for many yeears) I would hope that any engine management unit I have is built to a Toyota standard rather than to Honeywell / Bendix King / Garmin / JPI / Shadin / Goodrich [insert the name of the last piece of "avionics", brand new if necessary, which costs 4-5 figures and has packed up 3 times in the last year] standard....

The design and build quality of GA avionics ranges from inadequate to absolute c**p. A brand new plane today is probably comparable to the electrics you got in a Vauxhall Viva. The problem is what while a Viva owner didn't have much money to keep repairing it so bought a Datsun next time round, pilots don't have the choice (there is no "Datsun" plane), are expected to have unlimited deep pockets and so they either fly old junk which is just about airworthy or they spend whatever money it takes without comment. It's going to take a very fresh look at things to get the reliability designed- and built-in but of course it is possible.

[Mariner9]

Seems to be quite a split of opinions here.

I'm certainly not a Luddite - my house & car are both full of electronic gadgets & gizmos that I couldn't possibly do without now. Whereas the avionics & engine in a PA28 are 50's/60's technology at best.

I just was not of the opinion that the electric system currently fitted to the a/c was sufficiently reliable to run the FADEC. I note that the SMA diesel engine (which is JAR certified), although FADEC controlled, can be operated manually in the event of total electrical failure.

Sensible : The Wilkshe diesel has mounting kits for a RV9/9A & Europa XS. Although not sure whether you could class either as affordable!

Ninja : take your point about Carb ice etc, but that is something I, as a pilot, can control. Whereas there's not much I can do with the electrics. Would also appreciate Ghengis's comments on this topic.

BPF : Agree FADEC is a desirable advance in principle, but surely a/c electrical systems need similar advanced designs for safety purposes.

[gasax]

What makes Mariner think that GA electrical systems are unreliable? In the present designs they are very considerably more reliable than the recip and rotating elements. Then add in the fuel, carb icing and the nut behind the wheel and the element of risk from the electrical system failing is so tiny that it is negilible.

When Mooney put the Porsche engine in their aircraft it had a conventional (car type) ignition system and dual generators, buses and batteries - largely to meet the certification rules at the time. That made it complicated and heavy - not good things for an aircraft. The trick is KISS, two engines actually gives you more than double the chance of an engine failure - and most light twins simply delay the forced landing by a small period.

It is a little surprising that the FADEC does not have a 'limp home' ability - but you have to loose the generator and the battery to loose the FADEC - which will doubtless warn you of low voltage etc. long before the engine is likely to give up. A dry cell could probably keep the unit running for a couple of hours you're really worried about it (but of course you could never get that option certified!).

Given the numbers for engine failure from the present fleet, concerns over electrical systems in diesels are simply not warranted.

[Mariner9]

As I said in my 1st post Gasax , I've never experienced electrical failure, so the risk of it's occurence is probably more perceived then real.

What is "KISS" by the way?

With regards to certification, the SMA people told me the manual control backup was a requirement of their JAR certification. I wouldn't have thought that such a system would add much to the complexity, weight, or cost of a diesel engine, but then I'm not an engineer.

[A120]

Diesel engines look great, no doubt the CAA will make conversion almost impossible for most types. I would certainly rather replace the present engine with the new diesel engines with FADEC.