No mogas on the field. Only Avgas UL91 since 2012 (http://www.sust.admin.ch/pdfs/AV-berichte//2194.pdf)
Geez, the Conti C85 in my 1947 Cessna 140 has NEVER been overhauled and it’s still going strong after 68 years !
That’s neat. My O-320 Lycoming is at something over 1000 hrs and 44 years since new. If I fly it 50 hrs per year for the next 20 years it’ll be at around TBO. I guess then if I’m still flying and want to overhaul it for the first time, it’ll be good to go until maybe the year 2075. Somebody else will have to take over in doing the 50 hrs per year until that time!
My A65 was overhauled in 1997, having last been overhauled in the early 50s. The documentation for both overhauls is weak, I’m not exactly sure what I have, but it runs well. The good news is that you can overhaul an A65 very inexpensively. Unless somebody ground loops the plane or whatever there’s little doubt in my mind it’ll be flying behind the little A65 on its 100th birthday. I guess it’s possible I might still be flying then :-)
Once again someone mentions Rotax engines and all those that fly behind it say it’s great and does the job (I am in that camp – both through owning and operating a 912ULS and having quite a lot to do with them in the day job – as well as other aero engines) and all those who own heritage farm threshing engines dating back 75+ years try to rubbish it.
So – if the crankshaft runs in different bearings to a Lycoming, so what? What are the real, actual, genuine facts concerning actual issues with Rotax 91x engines – and I don’t mean ‘my mate overheard someone say the other day that blah blah blah….’.
Does the Rotax 91x series of engines do the job safely and reliably? Seems to.
Is it just that it wasn’t conceived in the USofA?
Once again someone mentions Rotax engines and all those that fly behind it say it’s great and does the job (I am in that camp – both through owning and operating a 912ULS and having quite a lot to do with them in the day job – as well as other aero engines) and all those who own heritage farm threshing engines dating back 75+ years try to rubbish it.
I don’t think the discussion here is anywhere near that level.
Technical dissent is fine.
I am all in favour of more technical information being contributed.
Just as many Rotax Owners/Pilots bitch about Contis and Lycomings as being unfit for an aircraft? You do it, too, (“heritage farm threshing engines”) while complaining about that very narrative.
Our C90, O-200, O035, our two O-300s, our O320, the two IO470s and even our 6A-350 run just fine, and as reliable as an engine can get, thanks. The Rotax 912 of our AeroClubs microlight, too. The 914 of several club installations, not so much. Our neighboring club has a downtime of the aircraft due to engine problems for about a year during the past 3 years – of course, mostly in summer. One 912S i know disintegrated slowly, so that after half TBO the engine was damaged beyond repair. One deadly accident with a trike in the past months in our vicinity was probably attributed to engine malfunctioning – it was a 912ULS.
Could that be singularities? Sure! Have they been maintained properly? Who knows? Have I seen engine failures of Lycomings and Continentals? Of course. Many of them (the IO540 of the skydiver 206 for instance) could be directly attributed to constant wrong handling. One O-320 of an aero club, too. They have flown that engine constantly with just 4 qts oil – that wouldn’t do much good on an 912, either.
Bottom line: There is more than one way to skin a spirit and the air cooled direct drive is still a viable option, that I would prefer over almost any geard, water cooled engine (even from Lycoming or Continental). I like simplicity in an aircraft much more than the two liters per hour Mogas, that the O-200 consumes more than the 912S.
all those that fly behind it say it’s great and does the job
I fly behind one, too, and I do say the same – it doesn’t keep me from always looking out for a place to land, in case the engine quits. Better safe than sorry.
4 qts oil – that wouldn’t do much good on an 912, either
Bwah, you would just throw about one third of that out the exhaust… (yes, I know that’s not what you meant)
And no surprise to me that the mishaps mentioned all concern the S variant – call me conservative but I do not like the practice of drawing more and more power from what is essentially the same engine block that was conceived for 80 HP.
I actually like technical discussion… ;-) and believe it or not something can be good in some ways and not so good in others.
The built up crankshaft and one piece rods used by Rotax make the crankshaft assembly slightly shorter, that’s the practical upside, at the cost of making the whole assembly non field serviceable. You can see how the compact rods allow the crankshaft to be shorter if you look at the photo. One piece rods are also slightly stronger but are not a choice that other modern four stroke engine manufacturers have made, for good reason.
The lack of cam bearings on the Rotax, running the cam direct in the cases, is a choice that a lot of modern manufacturers have made, to save money in manufacture. With good oil filtration it’s practical as long as you don’t want the cases to be reused at overhaul. There’s nothing wrong with that, but for myself I’d rather buy a different kind of engine regardless of application: almost all of my eight motorcycle engines have replaceable cam bearings too, because it was a factor in my selection of them. The only exception is a two stroke!
Re fuel consumption: as far as I can tell the main reason the Rotax uses slightly less fuel than typical is the fuel system. The Rotax engine runs at high RPM and is geared, both of which would tend to lower efficiency, not raise it. Dual CV carbs or EFI are what do it, and probably also being connected to an airframe that needs less average power in training service. Both Rotax fuel systems are more complicated and less reliable than the simplest kind of carb, as used on traditional aircraft engines (and tractors :-) The upside is that you don’t have to lean them manually to get best economy. I do own a number of vehicles with CV carbs or EFI, but for a constant speed aero-engine that runs mostly at constant power output, I see an advantage to simplicity: my planes can be maintained indefinitely, with tremendous cost saving in doing so, so simple is good. I also don’t fly enough hours for $6/hr difference in fuel use to affect me in any conceivable way.
I think one reason these discussions are good is that manufacturers have for some years been attempting to market more complex engines to GA, and failing. I think they may honestly not know why, other than the obvious development issues and difficulty bringing them to market. The Rotax 912 has done very well in spite of its relative complexity by selling to the LSA market – where things have never been expected to be in service for so long. I think if they’d succeeded in making Rotax V6 serviceable and brought it to the GA market, it would’ve been a very slow seller.
this is the factory of the bmw motorbike.
http://www.dailymotion.com/video/x2bh1ha_asi-se-hace-el-motor-boxer-1200-de-bmw_auto
and this the factory of rotax 912
the price of a complete BMW motorcycle is the same as a single Rotax 912
But the construction and quality is not the same
the price of a complete BMW motorcycle is the same as a single Rotax 912 But the construction and quality is not the same
As a BMW rider for 30 or so years, with close association with a large local dealership, I’d submit that the Rotax is better. https://rideapart.com/articles/most-reliable-motorcycles
Actually, I didn’t say that Lycomings and Continentals were unfit for aircraft use – I was merely pointing out where they came from, as opposed to the 91x series being designed from the outset as an aircraft engine.
No problem with technical discussion, either. But when something is inferred that it is in someway inferior or technically a ‘bad’ method of engineering then I don’t think that is painting an entirely fair situation to the causal reader. For sure, if that component is a common failure point, then okay – hence my request for examples of actual failures (rather than operator induced failure through lack of oil, mishandling or whatever).
Operating a 912 with ‘4 qts of oil’, would be in advisable given the oil quantity is 3 litres…
Interesting talk of the Rotax V220/V300 V6 engines. I was always under the impression that its development ended due to potential liability issues with some of the systems used (such as fears from the fuel system supplier). Is it a fact that it just didn’t work – if so where was that stated. No axe to grind, I just like facts over rumours.
Keep smiling. 
