I love and hate mysteries like this.
If you are of an engineering background you tend to move into "conclusion and fix mose" pretty rapidly.
If you have a scientific background the desire for data that can be analized is immense. A bit like breathing when you have been under water too long. Irresistable but can be fatal.
I can't get into engineering-mode until I can get past the data-mode. Unfortnately a scientific approach would involve a lot of money and testing to get good data. I can relate too, and sympathise with, the engineers who want to move on and either fail or fix. I appreciate those of you who keep posting infomation.
I know, there is NO CURE!!!!
Enquiring-Eric.
ORIGINAL: BillB
Only a theory, but during my post mortem I noticed two grooves in the leading edge of the stock rudder that lined up with the rear of the fuse. As you commented, Eric, none of the aircraft you have been commenting on have the stock rudder. I wonder if the unsupported section of the hinge points between the rear of the fuse and the rudder are causing some kind of vibration. I never heard anything remotely like flutter, which I definitely heard when my Rev Pro came apart. My Impact had never been snapped or spun. It did have a horizontal stab failure where the aluminum tube sheared off right at the edge of the fuse. I replaced it with a carbon fiber tube. The stab landed in a swamp. Thanks to Dave Snow for donating his stock stabs.