The pilot was conducting topdressing operations from a property airstrip located in undulating terrain. He reported that he had refuelled the aircraft after 11 flights, and that the accident occurred on the seventh takeoff after refuelling. The aircraft appeared to be operating normally, but failed to gain flying speed before reaching the end of the strip. During the subsequent collision with the terrain, both wings, both elevators, the engine, and the main landing gear were torn from the aircraft. The aircraft came to rest facing back towards the airstrip, about 200 m beyond and 100 ft below the level of the airstrip. The pilot stated that he had observed indications of localised whirlwinds and considered it likely that as he attempted to lift the aircraft from the strip, the aircraft's performance had been adversely affected by one. Weather conditions at the time were fine with a north-westerly wind of 6 to 10 kts.