It was unclear which of those events happened first.
The blade struck the front of the helicopter cabin three times and that would have happened within “points of seconds”, leaving little or no time for the pilot to react, he said.
McCready, who had investigated 38 fatal helicopter crashes and many non-fatal crashes, said mast bumping in Robinson helicopters usually resulted in the machine breaking up while in flight.
Mast bumping incidents in other helicopters were very rare, he said.
Robinson helicopters designed totally differently to anything else he had worked on and required extra training and safety awareness in New Zealand.
They are quite unique.”
Operators often had four-seater Robinson 44s to supplement their bigger helicopters and so they could offer a cheaper alternative for smaller groups.
In 2016, TAIC added Robinson helicopters to its watchlist, which resulted in organisations such as DOC banning their staff from using them.
“With the TAIC watchlist and all the things we’ve done over the years, there’s a great awareness of Robinson helicopters and their limitations amongst the flying community.”
The inquest is continuing.