What plane do you fly, Aart, with what engine?
I recall flights in a DA42 and that was very smooth. However the engines vibrated and generally banged about massively inside their cowlings but that didn't transmit to the cockpit because the engines were mounted on very elastic rubber mounts - perhaps 5x to 10x more elastic than the Lyco "Lord" or "Barry" mounts.
Overall the DA42 was considerably quieter than say a TB20 which is quite average. But not quiet enough to not need headsets, by a long way.
...these engines really sip fuel, and oil!
That's a good point re. oil - also the Austro & Thielerts only require 100 hr oil changes. The DA42 maintenance manual used to specify a 50 hr check (engine & airframe), but this was eliminated years ago.
The SMA diesel may have a similar favourable maintenance regime.
Does that mean 100hr services too? That's quite a saving, because a 50hr service on a SEP retractable is normally billed around €700 here in the UK.
Doing these yourself (as I do) is thus a big saving, even if I pay somebody to assist. Presumably that is also authorised on the diesels?
Does that mean 100hr services too?
Correct.
Presumably that is also authorised on the diesels?
It's definitely doable w/assist.
I fly a DA42 with 2.0 Thielerts. No difference in smoothness to the 1.7 btw. I also have quite some hours flying a DA42 with Austro engines. I do not perceive any difference in sound level, but -in spite that sound levels can of course be measured- it is known that the perception of noise is quite subjective.
Ref oil: of course it is not the major portion of the cost of operating an engine, but it does add up. I think the engine uses about one litre every 20 hrs or so. I fly conservatively (cruising at 75%) and I understand oil usage goes up significantly at higher power levels.
Yes, the engine mounts are quite flexible, which gives a bit of a strange sensation in turbulence where you see the cowlings move in relation to the prop spinner. You think this has to do with dampening noise or is it meant to protect the engine and it's ancillary parts? Maybe both.. Are the SMA mounts also that flexible?
Ref oil: of course it is not the major portion of the cost of operating an engine, but it does add up. I think the engine uses about one litre every 20 hrs or so. I fly conservatively (cruising at 75%) and I understand oil usage goes up significantly at higher power levels.
That is very hard to believe. It's a Mercedes engine with some small modifications but nothing major. The original engine consumes about 1l oil every 20 years. Is that oil lost through the prop? It can't be the engine really...
I imagine the crankcase ventilation setup for the Thielert is different than the Mercedes car.
Yes; I read somewhere (probably on the internet so it must be true) that car engines have a "much less ventilated" crankcase and this is why the oil lasts so long, and also why you can leave a car parked up at some Greek island for 6 months and the engine is not rusted up when you come back to it...
Oil costs are not really significant on the old Lycos. I burn 1 litre per 8hrs which translates to very roughly €1 per hour. The airworthiness limit is 1 litre per hour but an engine burning that is either freshly overhauled or is totally shagged.
What is more significant is the cost of the 50hr check IF you have to pay a company to do it - say €15/hr.
And more if you are diligent and change the oil more frequently than every 50... a lot of very good engine builders recommend every 25hrs (which I think is excessive on a regularly flown plane especially if you use Camguard).
Also, on a G-reg, the 50hr check is absolutely rigid (you can do a 10% extension) so if you are at say 30hrs and you want to do a trip down to Greece............. In that case a 100hr check is a lot more useful.
I know of a chap who flew a G-reg down to Australia and he needed the Annual to be done down there. The UK CAA insisted on two inspectors to be flown down there, reportedly business class, to sign it off. He found it "easier" to transfer the plane to N-reg while down there, do the Annual with an A&P/IA, and carry on... Says it all.
Also, on a G-reg, the 50hr check is absolutely rigid (you can do a 10% extension) so if you are at say 30hrs and you want to do a trip down to Greece............. In that case a 100hr check is a lot more useful.
That must be a UK thing. In Germany, 50h checks are not mandatory. I do my 50h checks myself, no 145 or A&P/IA involved. I do oil every 25h, at 6 € per quart that is 1,4€ per hour.
The only thing I am missing to do the 50h check 100% myself is a walnut nutshell sandblasting setup to clean the spark plugs. So I have to sneak over and ask whether I can use it...
I have no idea what a 50-hr check is, but FWIW I change the oil on my engines at 25 hour intervals for either $25 (little engine with no filter) or $50 (bigger engine with filter). Otherwise, I'm looking things over more often than every 50 hrs, more like every 5 hours.
Some people don't recommend blasting spark plugs, but if you're going to do it walnut shells would be good. They don't typically do a lot of damage to the substrate. (I usually scrape out the lead balls with a dental pick and then spray them with brake cleaner or similar)
PS I noticed the local DA42 having a little oil on the ground under the Thielerts - I'd assume from the crankcase breathers.
