We had a pretty good Oshkosh, all in all. We saw many old friends, purchased the various things I was looking for, and narrowed down our choices in oxygen systems. Terry spent the whole time with me, unlike last year when she bailed out to visit sisters after she had her fill of mud. This year she enjoyed it all, except for a couple of hours Wednesday morning when it seemed like the rain would never end and her fun meter was bouncing in the red zone for a while. We never did visit the beer coffin guy, as he apparently was ill and never made it.

Terry and I got home from Oshkosh late yesterday evening, after a much longer and more complicated day than expected. We left Oshkosh shortly after 9 Friday morning, and did a very short flight to Green Bay to get fuel, fill out an electronic EAPIS form to keep US Customs happy, and file IFR flight plans. Next stop was Sault Ste Marie, MI for lunch and to phone Canada Customs. Things were going well until just after we passed overhead North Bay, Ontario, when the engine developed a new vibration. It wasn’t a strong vibration, but it was strong enough so you were sure it wasn’t your imagination, unlike those mysterious vibrations and noises that single-engine aircraft engines often seem to develop as soon as you are over a large body of water. I started going through the various pages of the engine monitor, looking for anything abnormal. As I was doing that, I got a warning from the engine monitor that the “EGT Spread” was high. The EGT Spread is the difference between the highest and lowest Exhaust Gas Temperature (EGT). I saw that the #3 EGT was falling, and it bottomed out about 350 deg F lower than the other EGTs.

The engine was still producing good power, but something was clearly wrong, so I told Toronto Centre that we had an engine anomaly and wanted to divert to North Bay. They were very accommodating, and gave us clearance for an immediate left turn to north, followed quickly by clearance direct to North Bay and descent. I was already well within gliding range of North Bay, and I saw the airport, so I wasn’t too worried. The engine kept running, but it was backfiring once in a while. I did a 360 degree overhead arrival into North Bay, keeping well within gliding distance the whole way, and landed about 2500 ft down the 10,000 ft long runway. Terry kept her cool the whole time.

There was no big pool of oil after shutdown, which was a good sign. I was hoping the cause was a plugged fuel injection nozzle, as that left some hope of flying home that day, but I also wondered about a possible exhaust pipe failure, which was the only other thing I could think of that fit the observed symptoms. I pulled the tool kit out of the front baggage compartment, and removed the cowling. The problem was immediately obvious - the #3 exhaust pipe had broken at the weld where the exhaust pipe attaches to the flange that bolts to the cylinder, so the pipe was completely free of the cylinder.

I couldn’t arrange hangar space easily, and it was looking bad for a rental car, but we eventually got one. We pulled our gear from the aircraft, tied it down, and hit the road. I might be able to borrow an exhaust system part early next week from one of the many Ottawa area RV-8 builders, or I may be able to get a replacement part here by overnight courier by Tuesday or Wednesday. In any case, I’m hopeful to get the aircraft back home by the end of next weekend.