CAA may change rules around Robinson helicopters after 'mast-bumping' finding

The Transport Accident Investigation Commission last year said aviation officials have investigated 14 "mast bumping" crashes involving Robinson helicopters since 1996, costing the lives of 18 people. Photo / Wikimedia

The Civil Aviation Authority says changing rules around the flying of Robinson helicopters may be on the cards after a report into a fatal 2014 crash found mast-bumping was to blame.

The accident killed pilot Damian Webster, 37, when his Robinson R44 ploughed into steep bushland northeast of Mt Arthur in the Kahurangi National Park.

The chopper broke into pieces in mid-air when one of the rotor blades struck the cabin because of a phenomenon known as "mast-bumping", the Transport Accident Investigation Commission (TAIC) said in a report released today.

Although not ruling out the pilot contributed to the helicopter's in-flight break-up in October 2014, investigators said all Robinson helicopter models were susceptible to mast-bumping in low-gravity conditions.

Mast-bumping happens when the inner part of the main rotor blade hits the drive shaft in low-gravity flight.

TAIC recommended safety limitations and requirements applying to R22s and their pilots be extended to all Robinsons and their pilots, regardless of their experience, saying Webster would not have been allowed to fly at the time of the 2014 crash if the rules applied to R44s.

The Civil Aviation Authority, which sets aviation rules, said a number of recent rule and training changes had meant there had been no mast-bumping accidents in New Zealand the past two years.

But CAA general aviation deputy director Steve Moore said TAIC's recommendations could still be taken up in some form, after the authority's specialists met the Robinson Helicopter Company and the Federal Aviation Administration in the US.

"When it considers the recommendations in the TAIC report, the CAA will do so in the context of the outcomes from the recent work in the US," he said.

"It may be that this work will provide an outcome that will meet the intent of the Commission's recommendation."

Robinson Helicopter Company president Kurt Robinson rejected much of Thursday's report, saying Webster was inexperienced.

"TAIC suggests somehow that there may have been conditions or something that no pilot, no matter the experience level, could have survived - and we don't agree with that at all," he told Radio NZ.

Webster had logged 287 flying hours, but only 11 in the Robinson R44, according to the TAIC report.

The report comes after TAIC last year added the Robinson to its watchlist of most pressing concerns.

At the time, it said since 1996, aviation officials have investigated 14 mast-bumping crashes involving Robinson helicopters, costing the lives of 18 people.

There are about 300 Robinson R22, R44 and R66 helicopters flying in New Zealand, or about 40 per cent of the country's fleet.

On Monday this week, a Robinson R22 crashed near Reefton, killing 51-year-old pilot Noel Wilson. The crash is being investigated by TAIC.