I'm thinking of buying a taildragger LSA, many of which have a Rotax engine. Continental and Lycoming are the major suppliers of certified piston aircraft engines, and they are considered to be safe engines (for pistons!). I'm wondering if I should consider the safety and reliability of the certified Rotax engine to be substantially worse than that of the Conti O-200 (the only other certified LSA engine), and if there is any evidence one way or the other.
As far as I can find out, no one knows. There's no good data available on engine reliability from the manufacturers - although they usually don't share that information anyway - and nothing substantial that I could find from any third parties.
There is some information online, although it's mostly opinions and there's no real, consistent data to support it. This 2008 article compared LSA engine options including the Rotax and said that there were more incidents involving Rotaxes than Jabiru engines (excluding non-engine related causes), but there were also many more Rotaxes in service so the comparison isn't meaningful.
In fact, the article said that any comparison is difficult because the Rotax was (is?) primarily used in experimental aircraft:
The great problem in identifying engine-specific problems is that in the majority of installations, the engines power experimental/amateur-built category aircraft, where differences in mounting, accessory placement, cooling and vibration variations can instill issues that vary from one installation to another
And it also made the point that there are plenty of engine-related incidents involving Continentals:
And accidents involving Continental O-200-powered craft were as numerous as you'd expect for the length and depth of its presence in general aviation aircraft. Here again, many occurred through no fault of the engine. Still, numerous reports involved engine stoppages, heat-related power loss and other engine problems.
The article's conclusion seems to be that a Rotax engine is not (was not) significantly different from any other engine:
To paraphrase the words of one long-time Rotax service-center operator, the main problems involving the engines stem from many of the same types of problems—poor judgment, misuse, mismanagement and poor maintenance—befalling all aircraft.
I found various other forum discussions about engine noise (no conclusion), fuel efficiency (Rotax is better), maintenance costs (some preference for Rotax) and so on, but nothing authoritative. I suspect that a detailed, data-based comparison simply doesn't exist; finding anything for Lycoming vs Continental is difficult, even with the much longer history and larger installed base.
In general, engine comparisons seem to be mostly based on opinion and anecdote (as described here). That doesn't mean the information is useless, but you do have to spend some time sifting and weighing the opinions to reach your own conclusions.
Ron Wanttaja wrote an article about the subject in December 2022, analyzing accidents in the Experimental/Amateur-built category in the United States, based on the FAA accident database. I know that you are looking for information about the certified motors, but to my knowledge there shouldn't be any mechanical difference between a certified and non-certified Rotax 912 or Continental O-200.
The article is behind a paywall (I think), but the gist is:
- There are 1371 Rotax 912 (and another 2255 Rotax without further identification) and 1818 small Continentals (A-65 through O-200) installed on E/A-B aircraft
- Between 1998 and 2022 there have been ~250 accidents with small Continental-powered planes, 6.4% of which due to engines issues, and ~370 with Rotax 912-powered planes, 5.1% due to engine issues. Engine issues here means mechanical failures, not e.g. power loss due to fuel starvation
- The absolute numbers are very small (16 for Continental, 19 for Rotax) and show slightly more oil- and carburetor-related issues on the Rotax (mostly attributable to builder or maintainer error), more core engine and ignition issues for the Continentals
Wanttaja concludes that the Rotax 912 is safer/more reliable than the Continentals in general, and that there is no difference if you only look at the O-200:
As far as the small Continentals are concerned—well, the replacement is here. Data shows the Rotax 912 has better reliability than the traditional workhorses.
However, our “Continental” category suffered by lumping a number of different models together. Looking just at the O-200, the Rotax 912 and the O-200 have nearly identical statistics.