Juan Brown has picked up the VHA angle:
Something I need a bit of education about. I understand the 2/rpm bounce from aerodynamic loads on a 2-bladed rotor, There's some reference to the accident aircraft exhibiting tail wag at ground idle. I'm a little confused about the dynamics here; there's no aerodynamic load, is this just balance of a rotating mass? How would composite blades exacerbate this, compared to the OEM aluminium honeycomb blades?