Conducted 4/20/2013 –
John’s flight report to the Cozy list is below:
“In my last report I mentioned that I had completed the stall and stability test series at MGW. Having tested to a new weight limit, it was time for a complete condition inspection.
I had gotten a video borescope a couple months ago, and decided that this CI would be a great time to play with it. After completing the rest of the CI, I ran the engine up to temp and conducted a compression check. All was fine, so after letting the engine cool down, I started peeking in the cylinders with the borescope. All looked good on the first 3 cylinders I looked at. The last one I looked at (#1), I found a strange mark on the cylinder wall. It looked like a burn mark, or a piece of carbon stuck to it or something. The attached still11.jpg shows what I saw with the scope. I sent some pics to my FAA DAR, the engine shop that did the crankcase work, and to the manufacture of the cylinders. No one knew what to make of it. The manufacture suggested replacing the cylinder (possibly under warranty depending on what the mark was).
I pulled the cylinder and found that the mark was actually a spot polished to a mirror like finish (see the attached pic IMG2781.jpg for a little better view). I sent the next set of pics off to the manufacture who explained that it was likely a hydrogen bubble formed behind the nickel plating and due to expansion differences, that spot was pushed tighter against the rings creating the accelerated wear. They shipped me a new cylinder, and I spent last week replacing it. The good news is that I caught it early, before the plating in that area began flaking off. The bad news is that now I had to interrupt flight testing to spend a couple hours concentrating on breaking in Cylinder #1.
On Saturday, the winter that just won’t end relented for a bit and allowed me to conduct some flying. I tried to follow the Lycoming break in procedure as best I could given that the engine is now mounted to the plane, and it had to keep me in the air as well. The only good part about this never ending winter we’ve had here, is that it was still only 25F on Saturday morning, so cooling was no problem what so ever. The flight went well, the engine performed flawlessly, and after 2 hours I landed and pulled the cowl to inspect the engine.”
