Madhatter Posted March 28, 2019 Report Share Posted March 28, 2019 After removing my muffler I inspected it for cracks by visual means with no obvious issues. I then checked by pressurizing with a vacuum cleaner (output side). When sprayed with soap water I found 6 cracks occurring at the welds holding the flanges used to support the heat muff cover. The exhaust leaks only occured inside the heat muff area and do not show up externally on the outside of the muffler. This is a serious issue on all aircraft with an exhaust type cabin heaters, there are a lot of air worthiness directives on this on type certified aircraft. There have been a lot of accidents caused by CO and a lot of fatal ones. All mufflers of this type should be checked at each annual or condition inspection and is considered mandatory on all aircraft, just ask the FAA. Most inspect by close visual inspection but I have found it much easier to pressurize and use soap water spray and it will show cracks you can't see. In my opinion the welded heat muff supports are poorly designed, the flanges are welded only on the thin straight edge. When the heat muff cover is attached with the band clamps a lot of concentrated load is put on the flanges and they crack over time, there are only 4 small welds per flange. I had 763 hours on my ctsw. I welded mine but it is difficult to tig correctly because of the exhaust residue contaminating the weld. I had to reweld the flanges in a different location due to the crack repairs. Link to comment Share on other sites More sharing options...
Jacques Posted March 28, 2019 Report Share Posted March 28, 2019 good catch ..... thanks Link to comment Share on other sites More sharing options...
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