Towards the end of a spraying run the pilot noticed that the aircraft was drifting towards a power line running roughly parallel to the aircraft track. He attempted to counter the drift but the aircraft moved underneath the wire. The main rotor struck the line as the pilot attempted to manoeuvre clear and also avoid trees at the end of the spraying run. After striking the wire the helicopter swung through 180 degrees and the tail boom collided with a tree. Although the pilot had gained considerable experience on helicopters, most of this had been obtained cattle mustering. He evidently did not realise that a hazardous situation was developing in time to take safe avoiding action.
