Experience with Rotax engines installed in Sportcruiser aircraft has illustrated that the MAJOR reliability issue is the quality of the flexible rubber hoses.
Using cheap hoses just because they look the same as the original hoses is a bit like fitting a chocolate pin to a hand grenade. There is a very good reason that Rotax & the airframe manufacturer puts a life on hoses.
“Using cheap hoses just because they look the same as the original hoses is a bit like fitting a chocolate pin to a hand grenade. There is a very good reason that Rotax & the airframe manufacturer puts a life on hoses.”
Even for a Rotax 912 in a ULM this is stressed in the POH, or at least it is on the Super Guepard.
I am a life long sceptic on these sort of statistics without being able to study the methodology behind them.
Here there is a largish market these days whereby owners of certified Rotax powered aircraft will, when the engine reaches TBO or when a 2nd TBO becomes due, sell the engine into the ULM or experimental. I wonder how these figures have been treated in these statistics.
Without the methodology its database we could define our own statistics. As an example of this I would invite you to look at engine failures over the last few years on this very forum.
You might well get the impression that Cirrus engines are the most unreliable. Are they? Or is it because the reports are more publicised. As in the media are fascinated by the fact that a aircraft can safely return to earth under a parachute, whereas the Bonanza or PA28 which a pilot manages to land safely back on the airfield or even some other field, gets no attention at all.
aart wrote:
https://www.avweb.com/features/homebuilt-accidents-passing-the-engine-baton/
My club just ordered a new Evektor Sportstar RTC with a fuel-injected Rotax 912iS, so in a few years I might have something to report…
Airborne_Again wrote:
My club just ordered a new Evektor Sportstar RTC with a fuel-injected Rotax 912iS, so in a few years I might have something to report
Just be sure to read the Rotax manual carefully and understand how it works. I mean seriously. It’s easy to be tricked into believing it works exactly as an old fashioned thing, because on the surface it looks much the same.
Excellent analysis
LeSving wrote:
I mean seriously. It’s easy to be tricked into believing it works exactly as an old fashioned thing, because on the surface it looks much the same.
We are aware of that and we’re getting advice from a neigbouring club which already has two of them. Also, the gliding club at my airfield has a Samburo motorglider with the carburetted version of the engine.
Airborne_Again wrote:
We are aware of that and we’re getting advice from a neigbouring club which already has two of them
I was thinking specifically of the iS, and compared with carb Rotaxes. But, the iS compared with other engines as well of course. Luckily Rotax has excellent manuals. The POH don’t cover anything of how the engine works, it’s all about “do this, do that, don’t do this” and so on 
As you say LeSving, the manuals are great and very pilot oriented. Great figures to show you in a glance how to operate the engine.
And good info on the consequences of operating the engine on AVGAS, like 50 hr instead of 100 hr oil change, and advice on MOGAS: 1) make sure to use the right season fuel, and 2) consider the various fuel types as regards possible detonation:
Also a good forum to learn from:
Kind of funny to see on that forum that every once in a while someone pops up to suggest a different way of operating the engine in some aspect. He then (politely) gets gunned down by the excellent moderator and other experts and told to ‘just follow the manual’ 
Maybe the engine reliability statistics would even be better if all just religiously abide by the operating and maintenance instructions.
Maybe the engine reliability statistics would even be better if all just religiously abide by the operating and maintenance instructions.
Or alternately, and at the risk of going off the Rotax topic, they could expand beyond that and not have to maintain Bing motorcycle carbs nor EFI.
