Safety Officer Posted February 8, 2012 Report Share Posted February 8, 2012 Just an FYI for education: Crankcase fretting? What is that and how do you know you have it. You probably don't. It can happen with any engine, but we are only talking about a Rotax in this case. It has just happened to friend of mine with a 2005 912ULS. It seems to happen mainly with older engines and not the new crankcase that came out around Aug. 2006 and later. How do you know if you have it and what are the issues. The easy way to tell is after you shut your engine down go try and turn the prop. If it turns over like it does when it's cold then everything is good. If you can't turn the prop and it seems like you need Godzilla's help to turn it then you most likely have crankcase fretting. Some of the older crankcases will swell and put extreme pressure on the crank journals. After the engine becomes cold again the prop will turn over much easier. Here are a few things to check to determine if that was really the problem. One check the mag plug, it will most likely be clean or have a slight fuzz. Check the oil filter by washing the element like the video posted on this website and check for metal, it will probably be clean. Check the plugs and make sure they are clean. You need to do these last three to make sure you didn't have detonation and have a piston seizure which is a different issue. This last test is the important one. remove the #2 valve cover and loosen the four cylinder head nuts slightly. If the prop now turns over easy again and then when you tighten them back down it gets hard again then you have crankcase fretting. If you loosened the nuts and the engine was still hard to turn over then it most likely isn't fretting, but a piston seizure. Both of these are fairly rare, but can happen. As far as the crankcase fretting it must be fixed. It will eventually crack the case and could cause a total failure at some point. The fix is an overhaul. The price is around $12K not including the work to pull it off and ship it. This is one reason that some of us have the 2000 TBO extension and others were held back at 1500 hr TBO. The cases were made a little different. Now don't panic because you have a 1500 hr TBO engine or and engine pre Aug 2006. The over whelming number of engines never have any issues, but there have been a few rare cases of fretting. So far the ones I have heard about had around 700-900 hrs. and came from the 2005 time period, but that may not be the rule and only the ones I have heard about. If this does happen to you fill out the Customer Service Information Report(CSIR) and send it in. Rotax may help on parts, but not labor. Link to comment Share on other sites More sharing options...
This topic is now archived and is closed to further replies.