A little F= ma issue.
1) IF we assume the tail breaking off at frame forward of PB as an initial failure, then that would leave both HS and VS and Rudder plus APU as a unit.
2) IMO- Even IF at 400 plus mph the HS turned flat side to direction of travel, to develop enough force to rip both off at skin line would require a much higher unit mass traveling in the vector direction of travel to provide enough opposing force to break off HS
3) But IF 1) is not true ( meaning breaking off ***after/during *** breaking of HS ), then the mass- momentum of the whole plane forward of the break at the frame ahead of the PB, the resultant mass-momentum would be more than adequate to provide enough reaction/opposing force available to allow the HS to break cleanly at the skin line and the tail parts following a bit later
Keep in mind the time differences involved are very small re cause and effect and what happened first.
That being said- it is MY opinion that the initiating event was the flipping up of the HS- as the result of a) structural failure of jackscrew in some manner and b) reason for failure unknown at this time- but well place explosive is NOT excluded.
