The only important fact is that they failed. Additionally, because there is no known, consistent flaw, you cannot design a strategy to address the problem. You do not know what the problem is so how can you say that your approach has fixed the problem?  "It hasn't broken yet." can be said about all things until the moment of failure, when they fail.

Brent,

 

OK, I lied.  Some failure modes were reported.  Abrasion failure when passing thru partial rib.  I've got that one covered (uh, no pun intended) by protectively covering the Nylaflo.  Another reported failure at a kink.  I've straightened that out (again, no pun intended) by making sure there will be no kink. 

 

Not to trivialize the point you make, but I have a desk top covered with failures that "hadn't broken yet" until they did.  All of them are certified products - valves, a cylinder head, a magneto case, ARC radio, etc.  Also, a few uncertified items laying around like a custom prop, a Lancair approved spinner back plate, yada, yada, yada.

 

Vibration breaks everything it can, certified or not.

 

Scott

Sometimes I wish I were Grayhawk all the time.