The shipment I got from Hobby Services was a new engine, not my old, rebuilt one. That's ok but we lost the opportunity to learn why it ate the retainers in the first place.

They found debris in the bearing and that's new. I inspected the main bearing in the case, not out of the engine, after removing the crankshaft, and didn't see anything. It doesn't mean it wasn't damaged, just that I didn't see the damage.

I did not change the bearing when the engine ate the retainer the first time. If the bearing had metal bits in it, I would have felt some grinding and didn't. So I didn't think there was anything wrong with the bearing and kept it in service. Maybe there was damage and metal shrapnel in it, and it found its way into the piston skirt. Somehow it might have dislodged the retainer clip. It's far fetched but can't be eliminated as a possibility.

The lesson here could be that in such a failure, at least the main bearing should be replaced also. A big thank you to HS for giving me this bit of info at least. That and a replacement.

The engine had been incredibly reliable for nearly five years. It ran smooth, clean with minimal carbon build up, with power to burn and with outstanding field manners. I got spoiled with the ' Fuel, 2 Flips, Fly, Repeat'. The main concern, I have a pair of them in service now. Is failure of this type just waiting in the wings?