Report on fatal Glenbervie Forest helicopter crash released
It was "very unlikely" that a fatal helicopter crash in Northland was caused by mast bump, a report has found.
The Transport Accident Investigation Commission has issued an interim factual report on the Glenbervie Forest crash, which killed two forestry workers.
The accident happened while the pilot and contractor were undertaking a survey flight prior to spraying the Glenbervie blocks on October 31.
They were flying over forest land for timber harvesting company Rayonier.
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The bodies of Allan Jessop and Derek Hammond were located in the wreckage of their chopper, a Robinson R44.
The commission had added the Robinson R44 to its "watch-list" of safety concerns just a few days prior.
It cited the potential for "mast bump", which has claimed 18 lives since 1996.
Mast bump is contact between an inner part of the main rotor blade and the main rotor drive shaft atop the fuselage, otherwise known as the "mast".
The outcome is usually catastrophic with the helicopter breaking up in-flight, which is fatal for those on board.
However, the report said that the "confined nature" of the wreckage field and the type of damage found on the main rotor blades and the tail boom suggested that it was very unlikely that the helicopter had broken up in-flight, or that the accident had been caused by mast bumping.
The report said the Rescue Coordination Centre New Zealand received an alert that the emergency locator transmitter fitted to the helicopter had activated briefly.
"The RCC contacted the operator, who then phoned the ground crew. The ground crewman was already concerned that the helicopter had not returned from what he expected to be a 10-minute flight.
"The ground crewman and forestry staff then began a ground search for the helicopter."
The report said that an "intense" fire had ignited when the helicopter crashed.
"Smoke from the fire led the ground-based searchers to the accident site, which was in a native forest block, one and a half kilometres to the north of the loading area."
The commission was following further lines of inquiry, including the condition of the engine before the accident, the helicopter's maintenance history, the weather conditions at the time, and the procedures for forestry aerial spraying operations.