The Civil Aviation Authority has ruled that a crash involving journalist Rod Vaughan was caused by windscreen failure, not a drone.
Following the crash, which happened in March 2018, Vaughan said he believed a drone may have been the cause.
Vaughan told the Bay of Plenty Times the plane's windscreen "exploded" and a rush of air filled the cockpit.
"The wind coming through was so forceful that it blew my headset into the back of the plane, so I had no communications."
Neither Vaughan nor his son, who was also onboard, saw what shattered the windscreen, but Vaughan told media a drone was the "most probable explanation".
The CAA report said the aircraft was flying at an altitude of 1600 feet and a speed of 80 knots when there was a catastrophic failure of the windscreen.
This caused both cabin doors to come open, which affected the aerodynamics of the aircraft.
Vaughan carried out a forced landing in a paddock south of Waihi and suffered a large gash in his head. Both passengers were left hanging upside down, still strapped into their harnesses.
A yellow marking found on the windscreen during the investigation led the pilot to believe it had been hit by a drone, but the CAA investigation found it was ultra-violet radiation staining of the glass.
The CAA said the high UV levels in New Zealand can cause the degradation of the windscreen's plastic polymers, and recommends aircraft should be stored in a suitable building or with a protection cover.
Both Vaughan and his son have made a full recovery.