It's been three years since a helicopter killed Noel Edward Wilson, but the investigation into what went wrong has finally wrapped up.
The pilot, who was the sole person on board the Robinson R22 helicopter, died in a crash shortly after take off.
Mr Wilson was using the helicopter for a hunting operation on a wooded hillside near Reefton on March 27, 2017.
While it was climbing over densely forested terrain, the helicopter and its slung load struck the forest canopy then hit the ground.
Transport Accident Investigation Commission chief investigator of accidents Aaron Holman said in a statement today the commission was unable to determine conclusively what happened in the final seconds before the accident.
But he added that the accident happened after a series of factors lined up.
"The helicopter did not maintain a sufficient altitude before it struck the tree canopy and then the terrain, and the commission's final report describes how a series of risk factors aligned to make the accident more likely – including airworthiness, engine power and flightpath," Mr Holman said.
"The helicopter wasn't airworthy and it was unlikely the engine was producing its maximum specified power.
"When the commission's investigators examined the wreckage, they found discrepancies between the helicopter’s logbook recorded operational time and the life of major components.
"The helicopter's hour meter had been disconnected, the main rotor blades were time-expired, and the engine showed signs of wear inconsistent with the hours recorded in its logbook."
The commission found that Mr Wilson was conducting a commercial flight, which was beyond the privileges of his private pilot license.
"Everyone involved in private air transport and recreational flying should understand the risk to the public if an aircraft operator chooses to disregard Civil Aviation Rules for license category and airworthiness," Mr Holman warned.
"The Aviation Related Concerns system, available on the CAA website, provides a way for the public to raise concerns about this sort of behaviour."
The Civil Aviation Authority’s regulatory control and surveillance of the non-commercial aviation sector broadly aligns with relevant international standards and recommendations. For this reason, the commission made no new recommendations.