Any idea what would have caused this?
These are pics of con rod and piston out of my Super Tigre .45. I was flying it this morning in a new WM Super Stunts 40. I was just getting ready for a flight, with the engine idleing, when it suddenly stopped with what sounded like a backfire.. I put the starter on thinking that I'd need to tweak the needles a bit. Straight away, I could feel that something was not right. Turning the prop by hand, it only had about 180 degrees of movement before coming up against something inside. I knew this was the end of my flying day (I only took 1 plane with me).
I pulled it apart when I got home and this is what I found. As you can see, the gudgeon pin has been sheared into 3 pieces. There is also a piece missing from the piston skirt. This is what was jammed up in the crankcase. And there is metal debris all through the case and head and grey sludge everywhere. The liner is fine without a scratch on it.
Looking closely at the broken ends of the gudgeon pin, it looks like they have rubbed against each other a bit.
The landing just before, I had hit a rabbit hole and the plane nosed over, causing the prop to hit, and stop the engine from idle. This may have been a contributing factor. But I restarted it after fueling and away it went. I ran it up to full revs for a few seconds, then back to idle. This is when it stopped.