Patrick,

Your exhaust looks brand new.  Your problem must be a welding issue.

I had a crack in a different location at about 900 hours.  Close examination revealed that the flange that cracked was not quite parallel with the other three.  The outboard end of the flange was not sitting flush on the exhaust flange.  This introduced a bending stress in the flange adjacent the exhaust stud.

Chris

 

 

 

 

Chris Zavatson

N91CZ

L360 std