Patterson-Gardner's mother, Louisa Patterson, herself a well-known and experienced helicopter pilot, challenged Muse during tonight's meeting, questioning his explanations and statistics.
Addressing Muse, she said: "Thank you for not talking about James and Steve's accident while I was in the room because I would be very interested to see what bullshit you were going to say about it."
She had carried out her own analysis on the R22 and R44 helicopters, she said, and both showed problems.
Since her son had died there had been 65 fatalities internationally in the R44 and 40 were unexplained in-flight break-ups, she said.
"These are happening in the R44s. We thought there were problems with the R22s. But the R44s we thought were safe."
She branded the R44 "not fit for purpose anywhere", and told Muse the company needed to fix it.
She also challenged his analysis of other crashes.
United States-based Muse has travelled to New Zealand twice since the Herald published its investigation, meeting with operators, government agencies and associations. He has repeatedly argued the Robinson machines were not at fault.
During the emotionally charged session, Muse told the conference the figures around helicopter crashes needed to be kept in proportion, and argued just as many crashes were occurring involving other brands.
Using CAA crash statistics relating to accidents between 2000 and 2017, he said the AS350 had 34 accidents and six fatalities compared with its R44, which had 43 accidents and six fatalities, and the R22, which had 95 accidents and six fatalities.
He claimed a large number of the accidents were due to pilots exceeding the limitations of the aircraft and went through local examples of crashes where this had occurred.
The solution was training and education and nothing to do with a problem with the rotor some groups felt was not designed for New Zealand conditions, he said.
"There's an issue down here and the focus needs to be squarely on what the issue is and how to correct it."
Muse said while the accidents were "horrible", there had been a "terrible" economic impact to local operators who had been banned from using Robinson aircraft.
"The economic damage that is being done to hundreds of New Zealanders - the way they support their families. You may think I'm up here trying to defend our brand and that's true . . . [But] these mum and pop operators can't do anything - they can't make money because they have been banned. You can't fly them on government contracts - you can fly an A500 but you look at the safety records and a (R)44 is better than a 500.
"When we look at the R22 [crash statistics] we know this is unacceptable and that is absolutely unacceptable, but I've read and I've studied every single fatal accident from 2006 to 2017 and I don't see an issue with our aircraft.
"When you look at the R22 you have to remember that the least experienced pilots are flying them. It's a dominating aircraft that controls a large portion of the fleet. If everyone learned in a Toyota the accident rate would be higher."
Another operator agreed with Muse that the accident rate was due to pilot fault and said his own fleet had reduced significantly since a ban on some of the aircraft had been imposed.
