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By Vic Syracuse, EAA 180848, Technical Counselor/Flight Advisor
February 2017 - I was performing a prebuy inspection on an RV-6, when I noticed the right exhaust stack was so close to the cowling that the cowling had been burned. Usually that is caused by a broken exhaust hanger or misaligned exhaust stack. When I went to move it around, it was frozen in place, so the usual suspect hanger wasn’t the culprit.
I did notice a broken Adel clamp holding the exhaust stack, but as I ran my eyes further up the stack towards the engine, I was shocked at what I found. Someone had welded a patch right across the ball joint, which is there to allow the exhaust system to flex! Please don’t do that. The engine moves around in the mounts quite a bit, so there needs to be some flexibility in the exhaust system. That is what the ball joints are for. This fix would require a new exhaust stack to rectify, and I recommended not flying the plane until then. It certainly wouldn’t be any fun if that exhaust stack failed in flight and started dumping the exhaust heat on the fiberglass cowl!