Originally Posted by
Torque Tonight
Grenville, I think you misinterpreted my comments. I did not suggest that a stalled rotor should be recoverable. I said that I believe a stalled rotor with the collective fully down may still have some small rotation. The AAIB have stated that there was zero rotation, so even if there had been a double engine failure and a completely mishandled entry into autorotation (which I would not expect from this pilot) this doesn't quite add up. No rotation suggests to me a mechanical failure in the transmission. As the AAIB are indicating against that, I am quite puzzled by this accident.
TT, okay have understood you now, apologies for not catching your drift earlier.
Yes I agree. Even a "stopped" disc would have some small rotational movement created by the upward airflow. That this disaster is puzzling is without question.
The AAIB have stated that the aircraft impacted the building at "a high rate of descent" and when "neither the main rotor nor the fenestron tail rotor were rotating."
This means that between the "popping" sounds reported by eyewitnesses (and recorded in the bulletin) and sometime prior to impacting the building (a handful of seconds presumably) the drivetrain came to a complete and sudden stop, almost as though it struck something, which we know it didn't, and which is why I was expecting to read about a catastrophic mechanical failure.