Originally Posted by
JeremyThompson
...
Everything ive seen, and in particular the NTSB footage of the guy poking around the tail, suggests the tail rotor drive shaft bonds failed and cut the top of the tail boom open leading to loss of anti torque control, and an immediate yaw...
Hi Jeremy. In your recent posts, I can sort if follow some of your logic. I might come back to that later. But here is one for you and others to consider in the meantime:
First, I assume by "tail rotor drive shaft bonds" you mean that a coupling between the tail rotor drive shaft elements failed?
The footage of the helicopter emerging from behind the building appears to me to show the fuselage yawing anticlockwise as viewed from above [update: I can now see the clockwise yaw others had indicated]. The tail boom might initially also start yawing in that direction but then seems to fold back as if resisting the sudden yaw by its own inertia and aerodynamic loads. If there was a loss of tail rotor drive, then the fuselage should start yawing clockwise viewed from above (until pilot reacts and reduces collective and power) [update: which again is the direction of yaw most posters here were seeing, and I now can as well] .
I realise different people might perceive the direction of yaw in opposite directions [update: I have changed my perception over time].
You also associate the audio sound with a tail rotor shaft thrashing around. But the frequency has been associated by others with main rotor RPM. The tail rotor and tail rotor drive RPM is much higher so I would expect a higher frequency if that was the cause of the sound?