cracked exhaust on 912ULS

I've seen many and exhaust pipe or muffler welded without any issues. That said it all depends on how good a welder your pick. Find a good one that knows their stuff. I've been lucky at my airport field. We have one of the best I have ever seen. He even makes muffler systems for certified aircraft and makes beautiful welds.

Hi RL,

In my limited experience, welding up a crack is not the same as say replacing & welding on a new section or building from scratch😈

That looks very much like the OEM muffler Kitfox used to supply. It was not made by Rotax, but by some other manufacturer contracted by Kitfox. They quit supplying this muffler several years ago due to cost escalation, etc. Kitfox now uses the genuine Rotax muffler/exhaust system. I went thru this about 6 months ago, replacing my old cracked (1500 hour) Kitfox muffler on my 912 ULS with a new Rotax unit. The Rotax muffler looks to be higher quality and it is a drop in replacement for the old Kitfox supplied muffler-ALMOST. The main difference is the exhaust exit pipe coming out the end of the muffler is not centered on the end cap and is several inches longer. This means you will have to remodel the exhaust pipe exit hole on your fiberglass cowling. Also, the whole exhaust system (4 header pipes) must be replaced because the old Kitfox supplied headers do not fit into the Rotax muffler. Bottom line be prepared for quite a high total cost. Once it is in and cowl modifications made, you will be happy with it.