This was mentioned on another current thread...
I have no personal ownership experience but have heard various stories. Commercial users tend to be less than happy and have mostly reported having abandoned the experiment, while private users tend to report favourably.
How can the two be reconciled?
Our Club had a Katana with Rotax engine for years and was NEVER happy with it. We sold the plane and bought a Continental version - which is pretty trouble free ...
How can the two be reconciled?
I'd guess that maintenance which is perfectly acceptable for many private users is less acceptable for commercial or fleet use. I have a mental image (having never actually seen it) of a mechanic synching the two sets of dual Bing motorcycle carbs on a Tecnam twin. The EFI version eliminates that issue, but leaves a few others: for instance wood propellers typically come with some maintenance issues.
Having looked after a Tecnam P2006T for 600 hours and a P2002-JF single for 200 hours - over the same two year period, all I can say is that they were totally reliable. We also maintained a number of other singles and twin Tecnams for private customers.
The twin was mostly used for MEP ratings and renewals, as well as a bit of demo work and private hire. The single did some ab initio training but mostly conversion/PPL hire.
Before tending to the aircraft I went on Conrad Beale's excellent 3 day training course. Even after 20+ years working on GA aircraft (and before that 9 years in the RAF), attending a Rotax course is, in my humble opinion a must. They are not the same as the heritage farm threshing engines....
As for carb balancing - not an issue. It's carried out every 100 hours and if you know what you're doing takes about the same amount of time as timing magnetos - which you don't have to do on the Rotax.
Flying behind a Rotax 80HP 912UL, and having spent more time under the hood than at the stick, but with only theoretical/hearsay knowledge of the "traditional" US-an engines, I think the Rotax is rather more complex, and much more optimised for performance. It is only to be expected it is more demanding on maintenance, and even with perfect maintenance it would have its hands full to beat the reliability of the Lycosaurs. It makes up for that with a low burn of affordable mogas, while keeping the power to weight ratio within acceptable bounds.
As I can do the maintenance myself, with access to a vast store of knowledge and experience in fellow pilots/tinkerers (there's some 20 or 30 of these engines at my homefield, all maintained by their owner/pilot) and as I have learned to consider an out-landing a non-issue* in my low speed very-low weight craft, I consider the Rotax a good compromise. It offers very economical operation, and good availability of parts (many are from the motorcycle industry, and many have second sources).
Were I to fly IFR, and/or far and/or fast, I would need to find the budget for one or more engines more appropriate for that mode - more emphasis on reliability, less on economy.
As for syncronising the carbs: I have done that to full satisfaction, though I consider myself all but a genius in mechanics, with the simple method of comparing the vacuum in both carbs through a length of plastic tubing half-filled with water. The maharadja master guru** of course considering all that too complicated, HE can do it by the ear...
And, excuse me Silvaire, but what have wood propellers to do in this discussion? Of course the choice of propeller material can make for many hours of fascinating and edifying talk, but sure one can fit props of any material to any engine? My own pride and beauty has three blades of the noblest carbonfibre foremost!
*I must admit I have yet to make my first, though, which does speak for the Rotax's reliability, and when the prospect began to rise in likelihood on my last flight, I was surprised at the level of adrenalin my old body managed to produce and to handle...
**a rare clear picture of him is at and I hope it works from the first time now...
And, excuse me Silvaire, but what have wood propellers to do in this discussion? Of course the choice of propeller material can make for many hours of fascinating and edifying talk, but sure one can fit props of any material to any engine? My own pride and beauty has three blades of the noblest carbon fibre foremost!
Wood propellers are light and absorb energy and are therefore suitable for the geared Rotax which has the more complex torsional vibration issues that come with gearing. Carbon fiber can work OK too (a friend of mine designs and builds them for that and other applications) but have you seen a metal prop on a Rotax? I don't think I have, and I believe there's a reason. I'm happy to learn more, but that's my current understanding.
Balancing of the 2 carbs on the ROTAX912 is a matter of minutes with the right equipment during the annual or every 100 hours.
What I saw is that operators have no real understanding on how to operate a plane with ROTAX engines. When I was doing my IR in Florida and asked why the P2006 Tecnam wasn't flying. I got the answer that it had engines issues.
When I asked which fuel they were using, I got the answer 100LL, what should we use otherwise? When I asked if they were turning the prop before starting the engine in the morning, to get the oil from the engine back to the oil tank. I got a glance like if I was coming from another planet. When the next day, the Tecnam dealer mechanic came up and opened the first cowl, I saw the coolant bottle empty. So I understood that the mechanics and pilots from this flight school had no clue on how to operate a ROTAX.
The ROTAX912 series hates the lead contained in 100LL so you should use mogas. And if you use only 100LL, you better change oil every 25 hours. Also, the operator manual clearly specifies that the engine has to be gurgled by manually turning the prop before checking oil level. And if you run a water cooled engine without coolant, you are just not very smart (I didn't wanted to use a more explicit word).
Professionals who have been working with lyco and conti for years and are not willing to read an operation and maintenance manual and listen to others who are more experienced with ROTAX engines are certainly the root cause why these engines are problematic for them.
There are plenty of private and professionals operators who are extremely happy flying and maintaining the ROTAX 912 series of engines.
@Silvaire: good reasoning, though some Rotaxen have a vibration damper; and if ever I see a wood prop it is on a direct drive engine such as a VW or Jabiru... Would have to tour the hangars though, to find a metal prop on a Rotax - you might well have a point there.
Prop vibration on a geared reduction was a major issue on the early Centurion diesels, ISTR. But that is a much more powerful engine, of course.
PS I was glad enough to have the damper on mine - after an extremely rough landing I only needed to replace the prop and the nose wheel leg.
Are any of you considering UL91 for the Rotax 912 (and other engines)?
LAA AAN http://goo.gl/Gjw1bh
EASA SIB http://goo.gl/hEHv4x
I have been operating a Tecnam P92JS for the past 7 years, and some 870 hrs later, I found the Rotax 912S very reliable, and easy to maintain in some pretty harsh conditions.
Most of my missions with this aircraft are very low level marine animal survey flights. Slow speed, back end of the power curve, and the water cooling in particular has made it a non issue to operate.
From the SB history though, it seems to me at least that the older engines had fewer production related problems, no doubt due to the zeal of trying to reduce costs.
The new injection version looks very interesting. My engine will time out (12 year life limit) in two years, and I plan to replace it with another Rotax, no hesitation.
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