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Runtoeat

"On Condition" Rotax Maintenance

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There is now a growing population of Rotax engines on LSA aircraft that are approaching or going past 2,000 hours TIS.  Knowledge and topics that allow owners to watch for and respond to signs of trouble before it occurs is needed by those that are, or will be, using "on condition" maintenance of the Rotax.  In a recent thread on this forum, Corey and Roger commented on Rotax valves and valve seats.  This is something I wasn't aware of and hadn't heard about.  There is little to no discussion of "on condition" maintenance by "official" Rotax channels but there is an excellent core of experienced and technical people on this forum who are able to provide advice and details for this.  For those of us who will be using "on condition" for our engine maintenance, how about a separate category for our forum that keeps us informed and addresses this? 

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We have heard, mostly from Roger, that 912s do go 3-4,000 hours.  I know of one that has the 1,500hr TBO and is now beyond 2,500hrs.  Its good for me to hear specific reports like these, for instance until I heard this I figured I was not keep this motor for too long but now I think I will.

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When Rotax had their contest to find the longest in-service 912S/ULS without an overhaul, the winner had over 6000 hours.  I would not even blink when my engine hit 2000hrs if it was performing well.  I'd do an oil analysis ever other oil change (I'd do that after 1500hrs or so) and if it was not making metal, I'd just carry on.

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Andy, agree.  I also do the oil analysis at about the same interval as you.  The Rotax is unique from Continental/Lycoming for various reasons - nikasil cylinders, water cooled heads, etc. - and is designed to run well past 2,000 hours, provided this engine is properly maintained and monitored.  From a personal standpoint, I am interested in extending the life of my Rotax by using "on condition" and need a good area to get information and advice on this and believe that others also are interested in this.

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1 hour ago, Runtoeat said:

is designed to run well past 2,000 hours,

well, mine does have a 1,500hr TBO and a crankshaft fretting concern that keeps it at 1,500 vs 2,000.  Might be better said that there are design elements that permit longer life.

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Ed, your situation is is exactly why a place where owners/operators of Rotax can go to get information is needed.  I've heard about the fretting but have never seen pictures or read about any of the details about this.  If there might be other options available which would allow one to assess the condition of the engine, I have not heard any.  About the only information I am aware of is how much it costs to replace the block or the whole 912 engine when it reaches 1,500 hours.  This same scenario goes for the newer 912 engines that used to have a "mandatory" 2,000 hour TBO and now it is recognized that these engines are no different than all other internal combustion aviation engines and can in fact be maintained "on condition".  It would be of great benefit to the owner who is maintaining "on condition" to be apprised of issues that should be monitored but, again, there is great secrecy here.  My hope is that when Rotax engines have been in service for another few years there will be enough mechanics who have worked on them who will share their experiences and knowledge.  I have three mechanic friends and they offer informative and educational advice and knowledge about Lycoming/Continental/Franklin engines.  Any and all topics can be discussed and advice is given on any topic desired.  From my viewpoint, all things involving Rotax is shrouded in mystery and secrecy and this is a disservice to those who are trying to safely maintain their aircraft. 

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Fretting between the crankcase halves. This reduces the clearance on the crankshaft, causing it to bind up.

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If you don't have fretting by now you most likely won't. Most of those were 2006 & 2007 engines.

No use worrying about something that hasn't happened.

Although I have been a little anxious about the upcoming zombie hoards. 

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Roger and Corey, I should have added a desclaimer for you guys on my "rant".   The information you provide on this forum is appreciated by me and many others.

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5 hours ago, Runtoeat said:

Roger and Corey, I should have added a desclaimer for you guys on my "rant".   The information you provide on this forum is appreciated by me and many others.

Concur, Dick.

All those guys are a great resource to all of us who own and/or operate light sport airplanes.

I am very grateful for their unselfish contributions here.

Thank you.

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Jim and Bill, thanks for suggesting that the engine information related to "on condition" found on the other thread be moved here.  I'm hoping that there might be one "go to" thread where one might find topics/discussions that provide Rotax owners information needed to safely maintain the older Rotax engine.

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Just remember that the one key to on condition maintenance is fix the problem, don't put it off. Even if it means just taking the engine off and sending it in. I strongly recommend that people always put away lots of cash to fix a problem when it comes up, than waiting till it happens and wondering where they will get the money.

Life collects interest, and a lot of it.

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Good advice.  There comes a point where throwing good money after the bad doesn't make sense too.  IMHO, if I am unfortunate enough to have a failure that might cost a significant amount to fix and my engine is well past the recommended 2,000 TBO, it might be time to reach deeper than what the repair would cost, bite the bullet and just replace the engine. Owning a airplane is costly and this is a reality that I am prepared to face.  If I can't afford to fly safely, it's time to find a less expensive hobby.

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When I went to Rotax school we had a number of 912 engines to play with. One at 4680 hrs. came in for service due to oil leak from the o ring leaking on a pushrod tube. A couple that had failed leak down  tests from running on avgas and had carbon build up around the exhaust valves but were at  about time 1200 / 1500 hrs. one at 4100 hrs. with nothing wrong, and a 2000 hr. that was like new but in for overhaul due to hrs. Maintain these engines properly and don't use avgas unless you have to and they last very well. 

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2 hours ago, ct9000 said:

When I went to Rotax school we had a number of 912 engines to play with. One at 4680 hrs. came in for service due to oil leak from the o ring leaking on a pushrod tube. A couple that had failed leak down  tests from running on avgas and had carbon build up around the exhaust valves but were at  about time 1200 / 1500 hrs. one at 4100 hrs. with nothing wrong, and a 2000 hr. that was like new but in for overhaul due to hrs. Maintain these engines properly and don't use avgas unless you have to and they last very well. 

That engine sounds like a perfect candidate for a Zipper Big Bore conversion...

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