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l_luv2_fly(at)yahoo.com
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 Posted: Sat Apr 04, 2009 4:58 am Post subject: 9xx Crankcase fretting |
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Hi all,
I posted the same note on the Europa forum, but I thought it might be of interest on this list as well.
I just wanted to give you an update on my Rotax leaking crankcase. About a year ago I saw a small oil leak start on the engine just behind the gearbox on the flat machined surface on top of the engine. After a while the leaking area started to slowly progress along the case towards the back of the engine and then along the bottom. While I was at the Oshkosh airshow I went and talked to the mechanic from Kodiak to get his opinion. He told me that some 912 / 914's were getting crankcase fretting and over time the cases were damaged to such an extend that they had to be replaced. His advice to to have the engine stripped and inspected.
Well this winter I removed the engine and took it to Leading Edge Airfoil who has a rotax trained A&P on staff. He stripped the engine and sure enough it was showing signs of fretting. The engine has about 750 hours on it at the moment. Fortunately it was not too bad and he was able to dress the cases and re assemble the engine. He used a different sealant, 5150 I believe it was called instead of the red Locktite sealant that was on before. He tells me that Rotax now specify this sealant. It is a heavier material and apparently is swells a little after application, perhaps from heat, I am not sure. He felt confident that this would tighten things up and I should not have any problems. A couple of other things to note, at 750 hours there was no sign of wear in any part of the engine. The only thing he mentioned was a slight scuff on a cam follower that would have been from not priming the engine properly after an oil change. I remember exactly when I did that ! He as able to polish it out. There was a little bit of oil flashing on some of the piston skirts and he told me that this was from using either mineral or semi synthetic. I have been using the recommended Penzol motorcycle oil although this has dropped off the list in recent times, so I changed to the Valvoline Durablend. He was strongly recommending I go to a full synthetic oil. He also wanted me to stop using the Challenger oil filters, he tells me that they have less pleats in them. The only other thing of note was the Turbo charger bracket was broken.
So it would appear that Kodiak was right and if I hadn't had this work done I would have lost the cases. While he had it apart he overhauled the gearbox which was due, replaced the plugs, and the rubber boots on the carburettors, so my oil leak repair came to 3900 dollars. Ouch. Rotax really have no shame, the gasket set is over a 1000 dollars for something that has a trivial manufactured cost but there is little that any of us can do about that matter.
The aircraft is going to be a little while before it is flying again, I have decided to take a crack at some cooling modifications while it is all apart.
Paul
N378PJ
Europa 914
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daveaustin2(at)primus.ca
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| Posted: Sat Apr 04, 2009 5:39 am Post subject: 9xx Crankcase fretting |
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Rotax published an advisory years ago on the crankcase cracking. If I recall it was just where yours is leaking. Suggest you do a search on their site.
Dave Austin 601HDS - 912
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l_luv2_fly(at)yahoo.com
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| Posted: Sat Apr 04, 2009 7:36 am Post subject: 9xx Crankcase fretting |
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Hi Dave,
The SB you are refering to was SB 914-018UL R3. In my particular situation the cases had not cracked, but the two surfaces where the engine splits had ever so slightly rubbed until they fretted and leaked. This is a known problem to Rotax and the new style cases have been re engineered to address this problem.
Rotax are not able to offer any explanation as to why it happens on some engines and not others.
Regards, Paul
--- On Sat, 4/4/09, Dave Austin <daveaustin2(at)primus.ca> wrote:
| Quote: |
From: Dave Austin <daveaustin2(at)primus.ca>
Subject: Re: 9xx Crankcase fretting
To: rotaxengines-list(at)matronics.com
Date: Saturday, April 4, 2009, 8:38 AM
Rotax published an advisory years ago on the crankcase cracking. If I recall it was just where yours is leaking. Suggest you do a search on their site.
Dave Austin 601HDS - 912
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