Yesterday marked the one-year anniversary of the crash, and Transport Accident Investigation Commission (TAIC) senior communications adviser Simon Pleasants said the final report into the cause was "not imminent".
Investigations take about 18 months on average but can vary considerably, and Mr Pleasants declined to predict when the final report would be completed.
"The commission is very thorough.
"The point of transport accident inquiries is to examine the causes and circumstances of an accident in order to produce recommendations and lessons that the
An interim report was released in December by chief commissioner Jane Meares and chief investigator Tim Burfoot.
It noted three unreported incidents in the month prior to the crash when doors on the helicopter opened in flight.
"Evidence shows that a pair of over-trousers from within the cabin was drawn out in some way and became entangled in the tail rotor."
Alpine Group managing director Jonathan Wallis said at the time the interim report - and a second report suggesting "mast bump" might have led to the crash of a
Robinson R44 crash and the death of pilot Matthew Wallis, in July last year - were "disturbing".
"Since that accident in October we have been made aware of numerous incidents of doors opening in-flight on the same aircraft make and model," he said.
Mr Pleasants said interim reports were put out when there were "pressing matters" that required the attention of the industry.
