Here is the story:
I bought the Rotax 912 ULS engine for my Just Aircraft Highlander project. Some time had passed while I was building my Highlander. I did the first run of the engine after its installation in spring of 2025. When I checked spark plugs after that (I am a LSRM and iRMT for Rotax engines), I found that spark plugs in the cylinder #2 were black. I ran the engine a few more times, but still had the same issue in the cylinder #2. I used a bore scope camera to check the cylinders and found some oil in all cylinders except #3. Cylinder #2 had the highest amount of oil.
I contacted the dealer (Lockwood Aviation) and was told that I am three months out of the warranty. It was very difficult to get any response from Lockwood Aviation. I spent enormous amount of time trying to contact them: the tech person never answered my emails unless I called him and asked him to check his email and look at the pictures. To catch him on the phone was another challenge. Usually a lady answered the phone and was telling me that he is either assisting another customer or teaching Rotax classes and will not take phone calls or check his emails for the whole week. When I was able to talk to him, he advised me to change all valve stem seals, which did not make any sense, since it is a brand new engine. I replaced all valve stem seals anyway (as my expense of course), but as I expected it did not help. Eventually I gave up trying to get help from the dealer.
My internet search did not help me much, some people were saying that some oil in the cylinders on new engine is normal, so I continued with my Highlander build. I got the airworthiness certificate and started to fly in phase one testing.
For the first 3 flights, everything was fine, until last week. On April 13, 2026, I had partial loss of power on takeoff. I was able to circle back and landed safely. In the hangar I found that I lost the cylinder #2. I used the bore scope camera and found the same issue – all cylinders except #3 had some oil and the cylinder #2 had more than others. I removed the cylinder #2 head and found that it was full of carbon deposits. The engine has just over 6 hours on it.
After a lot of thinking I determined how to find the cause of the problem. It was looking like the oil is coming through the intake valve. With some creativity I pressurized the intake channel of the #2 cylinder head and found the leak around the valve guide bushing. I made a video of oil bubbles pouring out. So, without any doubt, it is definitely a manufacturing defect.
Of course, I tried again to call the dealer but not surprisingly was told that he is teaching classes and will not take calls or check his emails for the whole week. I told the lady that loss of power in the flight is a serious issue and she was able to connect me with another tech person. This other tech person said that it will be better to continue with the person whom I was talking before, so I asked him to ask the first person to check my email and he promised to do that. I never got any response. I couldn’t get any help.
I filed the Rotax CSIR report online but did not hear back from them also.
So my questions are – am I out of any options? Do I have any avenue to get the engine replaced? I believed Rotax should as a good will replace the defective engine because of its manufacturing defect.
I see some oil in other cylinders – is it normal?
Here are the pictures and the short video of #2 cylinder head testing.
Andrey
