Folks,
For what it is worth, I believe that severe negative G was major factor in both the Tasmanian and more recent accident, in the former case turbulence and standing waves were forecast, in the latter also reported, the weather was really fierce the night Steve Nott's aeroplane broke up.
I believe there is enough evidence of this, and I find it very difficult to believe that any pilot, in daylight VMC, would allow a runaway nose down trim to develop to a situation where the aircraft broke up.
I knew the pilot in the Tasmanian accident, and in my opinion she was a competent and careful pilot, and a tragic victim of circumstances beyond anyone's control.
Sometimes, but not always in an aircraft accident, the obvious answer is the correct answer.
Tootle pip!!