I guess we will never know the final flight manoeuvres by GD over Mallala all those years ago. Maybe not Vne + ; my memory may have be thinking of some other accident and is no reflection on Flt Lt GD.
What we do know is best summed up by Senator David McGibbon's speech to the parliament on the Senate inquiry into the accident which revealed a litany of stuff ups by GAF/ASTA and ARDU Engineering when the aircraft was returned to the RAAF after a couple of years. The Board of Inquiry was also heavily censored as delivering a sub-optimal report.
GD accepted the aircraft in good faith to conduct the test flight. He was let down by a whole lot of people from ASTA through to ARDU and onto the system set up by top brass.
Hope you gerry111understand my point of view.