Joe,
I had the same problem on my
SOOB during the first 50hrs.
First I lost the outlet pipe
in flight, didn't even know it until my wife picked it up on a walk about 50ft
past the end of the runway. All the weld was still on the pipe. Analyzing of
what happened I concluded that the crack where caused by fatigue, because the
"disc membrane" resonated at one RPM or another and the highest stress occurs
in the sheet metal where the weld starts. To do away with that, I
stiffened the joint to increase the natural frequency. Never had a problem
since.
At the next annual, I
found cracks all around the tang inlet pipes from the engine. The same
problem, but I did not see a way to increase the stiffness without adding a
whole lot of weight. So I went the other way in making the joint softer. The
results where the same, no more problems.
FWIW
Richard
Sohn
N-2071U