Thomas,
Westland is good at this game, but the TR on the 101 clearly has them buffalo'd.
That teetering design has a square cut-out where the bearing sits, so the loads pass thru a square, not exactly the best way to do it. I would guess that the real life loads are higher on that rotor than the tests performed, cracks form at the edges of the square and at least once, the rotor came apart.
The 50 hour interval is the real concern, and the Canadians just gave up wrestling with it.
I would hazard a guess that Agusta/Westland have tried to patch up the existing design bit by bit, and this has cost them the last 18 months of heartache. Sometimes it is hard for a design team to take their wonderful baby (that innovative tail rotor) and just shoot it, and start anew. In defense of the patch up philosophy, to start anew would take a minumum of 2 years for a tail rotor, if they did it with no resource limits (plenty o' money) and had good luck. Who knows but that the new tail rotor is going thru trials now?
Having been manager when such decisions are being made, I can assure you it takes guts (and money) to be truly decisive, and it is possible that this kind of decisiveness is just rarer than it should be.