What happened
On the afternoon of 31 October 2016, a Robinson R44 helicopter, registered ZK-HTH, was performing a pre-spraying survey in the Glenbervie Forest, north of Whāngārei. The mission involved a pilot and a forestry contractor flying over target blocks to identify hazards and confirm boundaries for upcoming aerial spraying operations.
While flying away from the survey area, the aircraft crossed a ridge and struck dense vegetation. The impact was followed by an intense post-crash fire that consumed much of the fuselage. The crash resulted in two fatalities.
The investigation
Investigators from the Transport Accident Investigation Commission (TAIC) examined the wreckage, which was concentrated in a compact area. The examination revealed that the aircraft hit the ground with a high rate of descent and low forward speed. The fire was so intense that it melted aluminum components and destroyed the fiberglass cabin structure.
Technical analysis focused on the main rotor control system. While investigators found that one pitch link was missing its attachment bolt, they concluded this was likely a result of the impact rather than a cause of the crash. Additionally, the team investigated the possibility of "mast bumping," but found no evidence of a bent driveshaft or rotor blades striking the cabin or tail boom.
Findings
Due to the extensive damage caused by the post-crash fire and a lack of other conclusive evidence, the specific cause of the accident could not be determined. While the investigation looked into the integrity of the rotor system and the presence of a cyclic extension, no definitive mechanical failure was identified as the primary driver of the accident.
Safety action
While no new recommendations were issued in this interim report, the Commission noted that the presence of an on-board recorder could have been instrumental in identifying the cause of this accident. The investigation continues to look into engine condition, maintenance history, and aerial spraying procedures.