Over The Top Helicopters owner Louisa Patterson said yesterday’s "unprecedented step" by the commission served as a warning about the aircraft’s safety that should be heeded worldwide.
Her son, James Louis Patterson Gardner (18), and Stephen Anthony Nicholson Combe (42), of Wanaka, were killed when their Robinson R44 crashed in the Lochy River valley, southwest of Queenstown, on March 18 last year.
Both were employees of Over The Top.
Ms Patterson said in a media statement the commission had shown courage and leadership by recognising Robinsons had a disproportionate accident and fatality rate as a result of its main rotor system being "prone to mast bumping and in-flight break-ups".
"Any aircraft that is prone to unknown, in-flight break-ups, killing people, should not be allowed to operate in New Zealand conditions, particularly for commercial activities like tourism, where the public have a trust in safety systems and certifications."
It was up to "regulators and the politicians" to take action before more people died, she said.
"I have suffered the ultimate loss and I don’t want others to suffer."
TAIC commissioner Stephen Davies Howard said in a statement that the commission and the Civil Aviation Authority had investigated 14 mast-bumping accidents involving Robinsons — killing 18 people — in the past 20 years.
It described mast bump as contact between an inner part of a main rotor blade or a rotor hub and the main rotor drive shaft or "mast".
The outcome was "usually catastrophic", Mr Davies Howard said.
"We know the condition results when low-G occurs — a bit like when you leave your stomach behind when going over a hump on a country road — or from an inappropriate control input.
"Low-G can be caused by turbulence, but it is not normally a condition that causes concern beyond discomfort. However, it can lead to mast bumping, which too often has fatal consequences in Robinson helicopters."
The commission had also identified the rate of in-flight break-up accidents involving Robinsons in New Zealand had not been significantly reduced by the adoption of US Federal Aviation Administration measures intended to help prevent such accidents. It had also found the format and terminology of Robinson flight manuals did not draw enough attention to safety critical instructions and conditions that could result in serious injury or death.
"Four of our earlier recommendations made as a result of Robinson mast-bump accidents have yet to be actioned.
"We therefore remain concerned that there is a real risk that we will see more of this type of accident."
About 300 Robinson helicopters are registered in New Zealand, making up about 40% of the total helicopter fleet.
According to the commission’s website, the watchlist highlights its "most pressing concerns, including transport issues posing "high social, economic or environmental risk", systemic issues affecting transport safety, or issues that policymakers, regulators or operators "have been slow to act upon".
