Spline Drive: Just a thought on the mounting locations of the transmission to the airframe as I ponder what you posted.
There are multiple mounting points. If only one failed initially, might the loads initiated by the first mounting point letting go be of sufficient magnitude to created a dynamic torque effect on the tail (hence the fold) and then as that restraint was lost the other mounting points let go sequentially, and then rotor head and transmission departed the aircraft? I don't think that "all of the mounting points let go at once" fits what I see on the film clips that I've reviewed so far.
(The ABC news link at 1:18 from a post further up shows the helicopter straight and level before the building blocks the view...not sure if anything visible happened between then and the helicopter re-appearing in the camera's field of view).
As I look at the film I get the idea in my head that it all happened so quickly that the pilot may not have had time to get the collective down (startle effect being a known phenomenon) before it all went horribly wrong.
Originally Posted by wrench1
FWIW: word is the MR, transmission, and nodal beam assembly departed together still attached to the roof/deck section.
Thanks. Were any attach points broken?
For crab: thanks for the info on the freewheeling unit.