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Rotax 912 ULS - Fretted CrankCase

in 912 / 914 Technical Questions 12 years ago

  • Re: Rotax 912 ULS - Fretted CrankCase

    by » 10 years ago

    Hi Barry

    Sorry to hear you have suffered from the same failure. Would be great to see action from Rotax on this clearly known issue with this range of engines .. their silence over the past couple of years regarding this issue has been nothing short of impressive.

    I ended up ordering 6 of these bearings: Rotax 933-326 Plain Bearing ""D"". I had some trouble getting confirmation which part to use too during our rebuild. After speaking with many people the consensus was to use the "D" bearing. You might want to try and confirm that with a dealer prior to ordering but it worked fine for us. When you order 1 bearing you get 1 shell, not a complete bearing (2 shells)!! So make sure you order 6 of them not just 3! Our top ends were spotless and in fantastic condition so we didn't change anything with the heads or pistons.

    Hope your rebuild goes well. What surprised us was just how simple these little engines are considering the amount of secrecy and concern over working on them. They really are nothing special, and are very straight forward to strip and reassemble.

    Thanks,
    Jonathan

    I finally got my crankcase split today and confirmed it was crankcase fretting. It looks just like Jonathan's pictures. The bearings show wear but no brass is exposed. The crank measures 1.7495 inches on all three journals. The journals appear to be in good shape but could stand to me polished a little. Everything else looks good. There's a little metal the the piston shirts on number one piston and some very light corresponding scratches in the number one jug. Nothing to really worry about.

    Jonathan, which bearings did you order for yours? There are two different ones listed.
      
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  • Re: Rotax 912 ULS - Fretted CrankCase

    by » 10 years ago

    Thanks Jonathan for the reply on the bearings. Your right, these are extremely simple engines. Of course, it would be much easier with manuals but we'll make do.

    My top end looks good as well. Will clean off the small amount of carbon in the chambers and maybe off the back of the exhaust valves.

    I noticed there are fewer o-rings inside the new case compared to the old case. Did you use the optional o-rings or gaskets under the heads of the bolts or under the thread inserts?

    Thanks,
    Barry
      
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  • Re: Rotax 912 ULS - Fretted CrankCase

    by » 9 years ago

    Update on the fretting issue. I was able to get the engine back together with the new case and started. Seems fine. Will run on the ground a few more times before I fly it. Prop was easy to turn after it got warmed up. No apparent issues. Haven't heard back form Rotax. The regional rep is trying to get some relief for me and has been most helpful.
      
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  • Re: Rotax 912 ULS - Fretted CrankCase

    by » 9 years ago

    I have a 912ULS with approximately 980 hours on it and the 1500 TBO crankcase. Have been getting high aluminum in the oil analysis which led me to believe the crankcase was fretted. Torque check on the prop was high but within specifications. Brought plane to Lockwood who confirmed the crankcase is fretted. Due to the amount of hours and the cost of a repair I am going to replace the engine. Lockwood has confirmed that Rotax will not offer any warranty on the engine. Does anyone have thoughts on what the engine with the fretted crankcase is worth? Besides the crankcase issue, the engine runs perfect, has always run on unleaded ethanol free, has perfect compression, etc.
      
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  • Re: Rotax 912 ULS - Fretted CrankCase

    by » 9 years ago

    Hi Doug,

    You still need to file a CSIR with Rotax through the rotaxflyingclub.com

    They handle the warranty in the Americas. Even with the hours they may review your case and give you some help. Don't listen to everyone else as they don't make the final decision. The worst they can say is no. I have seen engines with 800-900 hours with a major issue and rotax did help so don't wait or discount the idea of sending in the CSIR.
    Make sure you send in all your logbook entries with the report and or any confirmation of the problem in writing from Lockwood.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

    Thank you said by: Douglas Gunn
      
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