I got back out to the hangar on Wednesday, and pulled the oil filter off the aircaft. It showed similar metal contamination, after about 20 hours of operation as the previous filter showed after 50 hours. I’m not sure if that means the wear rate is increasing, or if the problem only started part way through the 50 hours on the first filter. Probably a bit of both.

I talked to Aero Sport Power. Given the amount of steel in the filter, and the observed reduction in power, they agree that the safe course of action is to open up the engine for inspection. I’ll pull the engine off after Oshkosh and ship it back to Aero Sport Power.

I’ve also got an exhaust system issue to deal with. I forgot to mention that last weekend, as I was focused on the more significant “metal in the oil filter” issue.

I discovered a significant crack in the exhaust system when I was doing the big inspection last weekend. The pipe from #3 cylinder, which was the one that broke off at the cylinder last year, has a 4" long crack near the outlet, at the Y that joins it to the pipe from #4 cylinder. That Y is all that would have been supporting the pipe after it broke off at the cylinder. Perhaps it was overstressed during that event and that eventually led to a crack.

This shot shows the bottom of the exhaust system. The crack runs along the left side of the weld, and then branches off at each end to start going around the exhaust pipe.

I pulled the exhaust system off today, and found that there was a second crack on the top side of the Y. That pipe wasn’t too far from failing. I’ll contact Larry Vetterman to arrange to send the system back again. The exhaust system is in six separate sections that fit together with slip joints. I’d like to get a whole new section rather than do a big repair, given the extent of the cracking.