A helicopter has crashed at speed into a paddock near Te Awamutu, injuring a passenger.
The pilot of the privately owned Safari 400 had been joyriding with a friend when the engine began "over speeding", police said.
Te Awamutu constable Ryan Fleming said the helicopter had just cleared power lines and was 10 metres high when the engine malfunctioned.
"He's realised straight away he was in trouble and he's tried to auto rotate which is land the chopper when there's no power but there was too much forward air speed and they were coming in too quick."
Witness Grant Organ said the helicopter bounced before coming to a stop.