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  #1  
Old 12-01-2017, 09:32 PM
waterboy2110 waterboy2110 is offline
 
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Location: SF Bay Area
Posts: 209
Default Rotax Piston Meltdown

As Promised - here's the thread.
Hope to keep it as objective as possible.
At 47 hours on a 103F day the #2 piston melted down. Temps from the EFIS showed engine running warm at 116 Celsius. Rotax documentation states 130C is red line and 120C caution should be used. This engine has only seen 91 UL 10% ethanol fuel and I flew it often during phase one in triple digit F temps - up to 107F I recall.

Contacted Vans and all they could tell me was to contact Lockwood. They didn't know of any other Rotax dealers.

Contacted Lockwood and guy on phone suggested filling out a word doc in instead of the Rotax web form - big mistake - don't make it if you have warenty issues. Never heard from Lockwood again. Repeated emails and calls went unanswered.

Contacted CPS while out on the road as the filing of the Rotax form is time sensitive. I did my training with Bryan and Ronnie Smith. Bryan was sympathetic and I forwarded him the form. He was getting ready for OSH but said he would take care of it. To this date (6 months later) I have no idea if Rotax actually knows of this form or my experience.

Met with Ronnie and Bryan at OSH and was literally laughed out of the Rotax tent for using bad fuel - Sad. Vans could only offer that perhaps I write to the forums - even sadder.

Vans doesn't make the engine - Rotax does. Rotax doesn't sell you the engine - Vans does. Imagine buying a Samsung television from Best Buy and having it fail under warranty only to be told to contact Samsung and then being told you plugged it in to the wrong voltage without ever having seen the failed product... I digress..

Reached out to Phillips 66 (parent of Union 76) and they were very concerned that their fuel may have damaged my engine. They responded within two days and once they found out it was an aircraft engine they escalated their investigation. The next day I was on the phone with the head of Quality for the west coast aviation fuel supply. Once he found out I was using MoGas he became very concerned. They sent out a test crew and pulled a sample from the tank. The sample came back as advertised - 91 UL.
I expect Phillips spent a few thousand on helping me. They ran the incident through legal and I was told they are 100% defensible. They absolutely DO NOT advocate the use of their MoGas for aviation - under any circumstances. They felt that if someone would have been hurt Rotax would be accountable.

So back to Rotax - good fuel - now what.
Scratch their shade tree mechanic ars and settle on the cooling shroud Vans has you put on.
It's plausible - the design is such that #2 is starved until the plenum is fully charged. Interesting that Vans eliminated this from the kit. My personal opinion is that they were pressured by Rotax because they were asking non certified builders to dissembled a new engine. This in itself would violate the warenty.

So here we stand, 6 months later.... crickets.

I've replace the engine and now that the rose colored glasses have come off this will be my last Rotax. There's no doubt it's experimental. Nylocs firewall forward, no safety nubs for safety wire. Oil filter safety non-existant. Throttle linkage - I could go on and on.

A close friend was a Rotax distributor for many years overseas and phoned the factory. They asked him a series of questions and at the end of the call they said they would replace the engine. No one in the US ever asked me those questions (did I do the 100 hour at 25 hours - can we see the EFIS data?) That call was of no use since you have to work through you local distribution and they've settled on "it's my fault".

My conclusion is that the engine is "marketed" to operate on 91UL to 130C but I have a box of parts and EFIS data that says it won't. The cooling shroud most certainly contributed to the problem and I suspect there's something to Rotax pressuring Vans to remove that from the kit. I sincerely doubt that Vans simply forgot to put the shroud back on while checking the engine mount and just flew it for a year. There's also the fact that the engine post failure would not pass ignition check. I cannot reason that a dead cylinder would cause a drop on one ignition. Rotax completely blew this off. I may never know unless I get around to swapping out ignitions.

I do love this little plane but you should understand I'm $47000.00 into my firewall forward at less than 60 hours and not happy about that. I'm still struggling to get all the vibration out of the new engine and have no faith in Rotax or their support. I've heard everything from this has never happened to you should get a new engine.

The Cessna is nearly sold and I may begin on a 7 and get back to Lycons and Mags that I can trust.

Lots of pictures - Attaching them here screws up the page format. The story will evolve perhaps with your input.
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Last edited by waterboy2110 : 12-01-2017 at 09:33 PM. Reason: spelling
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  #2  
Old 12-01-2017, 09:59 PM
rongawer's Avatar
rongawer rongawer is offline
 
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Location: Brentwood, CA
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I appreciate the information. Itís no fun getting the run-around indeed. Iím admittedly not that familiar with Rotax, but why do you need to get a whole new engine if itís one cyclinder that failed? If I had a failed cylinder on my Baronís IO-520, and I have - I just replaced that cylinder and then kept on flying.

The same would be true for the UL engine, where each cylinder is essentially a separate accessory on the engine - just replace it. Is this not possible on Rotax?
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  #3  
Old 12-01-2017, 10:09 PM
jnmeade jnmeade is offline
 
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Location: Iowa
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Based on the attached documents it appears this was a 912ULS, do I have it right? Good luck on keeping this thread objective. I hope you can so we can all benefit from your findings.
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  #4  
Old 12-01-2017, 10:11 PM
waterboy2110 waterboy2110 is offline
 
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Location: SF Bay Area
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Hi Ron,

The crank in these engines are pressed assembled around each big end rod that isn't split. There's no way to confirm that the crank is airworthy. CPS said they split the case and the cam was pitted. I have no evidence of that but I have the engine.

This is why I was looking into the UL. If I was going new engine why not now. But after speaking to Ray it was clear it would be $27k. If I had more patients perhaps, but I just spent nearly 5 years building it and honestly it's a bit embarrassing.

Yea - any other engine - just clean it out and replace the parts. These engines aren't really serviceable beyond TBO IMO.
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  #5  
Old 12-01-2017, 10:26 PM
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rongawer rongawer is offline
 
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That’s really disappointing to hear Jim.

And I completely understand the cost to change to a different engine; it would definitely not be a simple swap out, but would be cost effective if you were doing it from the start.

I had thought Rotax’s were fairly simple to dissemble and repair; it sounds like that’s a misperception on my part. One of my attractions to the UL was the simplicity, documentation and availability of a complete OH kit at a low cost.
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- RV12, N975G, SN 120840, Build in progress...finishing up.
- BE58, N1975G, stimulating the economy one flight at a time.
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  #6  
Old 12-01-2017, 10:28 PM
scsmith scsmith is offline
 
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Well, this all really sucks. Sorry for your experience.

I wonder how widely known it is that the engine is not really serviceable. I know there are motorcycles where the crank and rods are assembled this way, but I think you can push out roll pins and disassemble the crank.
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  #7  
Old 12-01-2017, 10:47 PM
waterboy2110 waterboy2110 is offline
 
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Quote:
Originally Posted by scsmith View Post
Well, this all really sucks. Sorry for your experience.

I wonder how widely known it is that the engine is not really serviceable. I know there are motorcycles where the crank and rods are assembled this way, but I think you can push out roll pins and disassemble the crank.
Yea - Harley's have solid big ends - but they're serviceable.

I'm sure I could have rebuilt the engine for maybe $5k less than new but I would not have been comfortable with it. Besides, if Rotax were to ever come through with a warranty this engine belongs to them.

I needed to get the plane back in the air and move on. I didn't spend north of $70K for and 4 years for lawn art.
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  #8  
Old 12-01-2017, 10:51 PM
waterboy2110 waterboy2110 is offline
 
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Quote:
Originally Posted by jnmeade View Post
Based on the attached documents it appears this was a 912ULS, do I have it right? Good luck on keeping this thread objective. I hope you can so we can all benefit from your findings.
Yea - 912ULS
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  #9  
Old 12-01-2017, 11:06 PM
waterboy2110 waterboy2110 is offline
 
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Quote:
Originally Posted by rongawer View Post
That’s really disappointing to hear Jim.

And I completely understand the cost to change to a different engine; it would definitely not be a simple swap out, but would be cost effective if you were doing it from the start.

I had thought Rotax’s were fairly simple to dissemble and repair; it sounds like that’s a misperception on my part. One of my attractions to the UL was the simplicity, documentation and availability of a complete OH kit at a low cost.
I wouldn't say Rotax isn't serviceable, the are pretty simple engines sans the gear box. This engine made major metal and the only way to return it to service is to completely go through it. It took out #2 and #4 perhaps from FOD bounce.

I dug up a Rotax vs UL thread yesterday and it seemed the pushback was the ECM being powered by the ship in case of Alt failure ( I admit skimming the tread). Given that they're moving onto the 914 and it has the same brain to keep alive perhaps Vans will consider the UL.

I do want to see your install. Ray made a good pitch. Going EAB is no big deal. I hope you have success and publish the results for all to see.
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Last edited by waterboy2110 : 12-01-2017 at 11:28 PM. Reason: spelling
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  #10  
Old 12-02-2017, 01:53 AM
AndrewR AndrewR is offline
 
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Location: Ballarat, VIC
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Where did the manifold pressure and RPM fit in with the chart in Rotax SL-912-016? I know there has been debate in the past because the RV-12 has trouble meeting the minimum 5200rpm specified at WOT. Maybe we are learning the conditions where that is important.

What was the 116C measuring? Temperature measurement in the Rotax is confusing due to a number of changes along the way. From my memory of trying to keep track of the changes (check your manual, don't rely on these numbers!):

Originally the measurement was head temperature and 130C was the limit. This is due to detonation margin - the lower compression 912UL has 150C limit.

Then they introduced an additional 120C limit on coolant output temperature due to the potential of coolant boiling at higher temperatures.

The most recent heads measure only coolant temperature, and 120C is the limit.

In between times there were options for waterless coolant, which dispensed with the 120C coolant limit but made the whole engine run hotter. That doesn't seem to be permitted with the latest heads.

Even if it is head temperature, 116 seems very hot.

Rotax also list taking hot air from under the cowl as another potential contributor to detonation. I know many Rotax powered aircraft do the same, but it's possible that with hot under-cowl air, high CHT and high engine load due to low RPM at WOT that you found the combination that Rotax are warning about.
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