both spindle assemblies and their respective main rotor blades had separated from the hub
This what has got me? It seems quite clear and presumably written by a helicopter experienced person. It may be of course that it was the blades, outboard of the blade spindle housing which failed, which is where all other blade inboard failures have occurred. If it was a -2 blade and one failed, I guess it not unreasonable for the other to fail immediately given the massive torque spike. That is, if it already had a progressing fatigue crack.
I note in
this link where there is an analysis of similar failures done by OZ ATSB that on none of the Aircraft mentioned did they carry out an inspection of the second blade to see whether there was evidence of fatigue crack commencement.
Except for the first, which was a -1, the rest are -2.
Thanks Gordy for this
one which I think is the one you refer to, with 31 accidents. All appear to relate to being either mast bumping or low RRPM causing blade stall, or unexplained M/R divergence.
I still cannot find evidence of either hub, spindle or spindle bearing failure.
Cheers tet