Exhaust pipe beneath the Carb Heat Muff ??

[Avidflyer2]

Here is the reason why you should inspect the exhaust pipe section covered by the carburetor heat muff. Use a mirror and flashlight, or a borescope if you don't take the heat muff apart on 100H or Annual Inspectionsl

I could not find the time in service on this exhaust pipe. Several entries have said, "..replaced exhaust pipe.." without part number or location, ie: right rear stack pipe. Yep, came off of a Piper Cherokee which has been flown regularly in the past year...

I find it curious to see the extensive number of wrinkles in the pipe which must have appeared way before the pipe ruptured or cracked. I think the wrinkles are caused by the large overhang moment by the unsupported weight of the muffler behind the engine. Cracks or ruptures in this section of pipe allows the exhaust gases to be ingested by the engine whenever Carb Heat is selected, or basically all the time as the flapper valve in the carb heat selector box is not exactly air or exhaust "airtight".

 

[Raptor05121]

 

[kf6iat]

 

[Avidflyer2]

 

[magman]

 

[N7655W]

 

[kf6iat]

 

[vaflier]

 

[Avidflyer2]

 

[vaflier]