Rotax 912 ULS - Oil in cylinders in brand-new engine

Update on the case.

I finally got a message from the dealer with recommendation to perform the crankcase pressure test. I replied that the engine is not in running condition because of the faulty cylinder head, that’s why the test is not possible. But I did another pressure test of the cylinder head and sent him pictures and the link for the video. I asked two questions as well:

1. Is it normal to have some oil in cylinders in the new engine (this question is regarding other cylinders where there is some/ insignificant amount of oil)?

2. How the valve guide is installed - is it the press fit?

Next day I got  a reply email: the dealer said that the test is very impressive and he is thinking that the way forward is to send my cylinders heads to them and maybe test rig as well for results verification by Rotax. But my questions remained unanswered.

Well, I don’t want to become a hostage of Lockwood with disassembled engine and no cylinder heads, so I replied with a different offer – suggested that they should send me the new cylinder head and I will send them the defective one instead. I said that I will install that new cylinder head, and fly with it, and monitor other cylinders very carefully. Since the test rig is easy to assemble, I provided him detailed description of the test rig and my test procedure along with pictures of it.

And I repeated my unanswered questions again and asked one more – what is included in the “cylinder head assembly” in Rotax catalogue?

The dealer did not respond: I never heard from them after that (since April 28). The situation is exactly the same as in May of  last year – as soon as I asked to replace  the defective engine, they stopped talking to me.

But I have some other interesting news – I checked cylinders on another 912ULS engine with 172 hours and I got exactly the same situation – some cylinders are dry and some have some oil in them (see picture). I talked to a few Rotax 912 owners and asked them whether they ever looked inside of the cylinders - they didn’t. But one guy showed me the picture of his sparkplugs and some of them look very similar to my ones (see picture).

So now I can say that other engines have some oil inside of cylinders. I can’t say whether it is normal because not all cylinders have it. What is worrying me that dealer is ignoring this simple question. With their experience they should know the answer. Because of all of that I think something is going on here with oil in cylinders and people just do not pay attention to that and just replace fouled sparkplugs. Maybe it is just a nature of Rotax engines? Maybe all of them have some degree of imperfections, but they just don’t reach the point of a failure?

Now I plan to try finding the problem with my cylinder head that failed in flight. I am planning to remove the valve guide and find the reason of oil leaking.

Also, before disassembling my test setup, I decided to do another test of the failed cylinder head, but with lower pressure this time. I applied just about 8 psi of air pressure and, sure enough, it is still leaking. It is not as aggressive as with 35 psi. The bubbles are not big, it looks like foam (see the picture).