Thanks guys.
Back to square one, I've got enough doubts. Avidfoxflyers say stress riser is mentioned in the avid manual. I do not have an avid manual, and I did not see it mentioned in the 1989 KF manual (maybe its in there). 43.13 does have it so no excuse.
Under load, I can see a stress riser that may originate from it.
EAA around here mainly builds RV's, and they would have valuable input.