@ CONSO
I do not see how b) would be possible. The movement of the HS is physically limited by the slots on both sides of the fuselage, which do not permit travel beyond permissible range, even in case of a jackscrew failure.
For the HS to be able to pivot 90 degrees around the rear hinges, the lower half of the support structure and the bottom of the fuselage would need to go first (which it apparently did at some point), but that would turn the HS downwards. On the video screencap it is clear that the left HS failed UPWARDS, meaning pressure came from the lower surface. That would require a 90 degree turn upwards, but this would be prevented by the VS which is clearly still in place.
Also I do not believe the control surfaces have sufficient structural strength to exert such pressure that would break the tail off. The fuselage when intact is very strong and resilient to any bending force. A downward pressure on the tail would simply pivot the aircraft around the centre of lift. If the pressure is sudden and strong enough, the HS would fail first and downwards, before the fuselage would (eg. BOAC 707 in mountain wave over Fuji in '66)
I really do not see any scenarios corrobated by evidence from wreckage where the HS failure could have been the initiator, even though that was my prime suspect too until the HS photos surfaced.
PS: It's a good morning here
