EXHAUST INSULATING WRAP

I purchased my, yet to be completed aircraft project, with engine already installed.

The builder has done a magnificent job, with attention to every possible little detail.

One of those details is a black ceramic coating of the exhaust pipes. I note that Rotax advise against this practice.

In the past I have used heat shielding & some targeted "wrap" & tube insulation, where exhaust/heat proximity to vulnerable systems/materials has require it.

I have no experience with ceramic coating - what are the likely benefits/drawbacks?

The only way header wrap could actually damage the stainless exhaust pipes is if one or more of these things happen.

Broken exhaust pipes happen fairly regularly from vibration and poor welding on the joints and when the pipes are forced into position and not secured in just a relaxed position of operation. I have seen interior melt downs from broken pipes, but none of those ever had wrap.

So my question would be for this incident did the pipe just fail like many do or are you positive the wrap caused the failure? Out of curiosity what made you think the wrap was at fault? Plus if pipes break the wrap usually helps to reduce the exhaust damage..What would you have said if there was no wrap involved? 

Wrap not installed properly would be cause for concern and cause excessive heat. Other factors are poor air circulation in the cowl or overly high EGT temps adding to a heat issue and many exhaust pipe breaks are just due to vibration which is the number one cause of pipes breaking and of course poor welding jobs. This type of pipe failure has been going on for decades. I've had to repair under cowl heat damage from broken pipes too many times and yes if the break is in the wrong place and the engine is kept running it could cause a fire. At the normal EGT temp range that stainless steel pipe should have zero issues. The stainless would have to surpass its temp range and that shouldn't happen with proper wrapping and, cowl air flow and proper EGT range. Header wrap by itself won't cause stainless to fail. It's used around the world on exhaust pipes and has been for decades.

What of ceramic coating ??

I have heard that some have done ceramic coating, but I personally don't know of any.  I haven't read on any forum about issues, but who knows? Maybe someone here has more real time knowledge and experience with ceramic? 

Hi All

Apparently some are not keeping up with the latest documents from Rotax on this issue.  Please see the SL, service letter, on this subject...attached.

Cheers