912 ul exhaust

[Flyin Farmer]

Hello, Iam getting close to my AW inspection and ran into a problem , after doing my weighing for WnB I put fuel in aircraft and did an engine runup. All engine temps were well within limits and all worked well however after shutdown I was inspecting for any leaks ect. and I noticed my cowling had gotten so hot below the muffler that it had bubbled the paint. The muffler I have is heavy about 9.5 lbs. and has dual exhaust pipes I do not know if it is a rotax muffler or not it was a hot day about 90 degrees but until now I have not had an issue. I pulled muffler to check for any obstruction and found none, any ideas? I do not have an EGT gauge ,could it be the wrong muffler? I have not found any pics of 912s having dual exhaust pipes.

[efwd]

Not sure I understand correctly but I think you say this aircraft has yet to fly. If it has then you may have a change of some kind in your engine I suppose. If it is a new build, many people have been putting the kevlar heat shields on the cowl. https://www.aircraftspruce.com/catalog/eppages/kevlarheatshield.php?recfer=13692

Pricey but not as much as a new cowl. There are many sources for this stuff to include automotive supply stores.

[Dave S]

Greg,


I don't have the same model Kitfox as you so I might not be able to help directly; however, in general terms, the paint bubbling you describe normally means the heat source is too close to the item being damaged. Mufflers are going to be hot in any case.



Is the paint bubbling on the whole bottom of the cowl under the muffler or just where the exhaust pipes penetrate the cowl?


What kind of paint is on the cowl?



Might be useful if you could upload a photo of what you are experiencing.


Another thought would be to contact Kitfox Aircraft - at the least they should be able to identify the muffler you have and if it is the correct one.