The pilot was conducting spraying operations over an irregularly shaped paddock. Power lines were located along two sides of the paddock. At the end of a clean-up run conducted parallel to one set of the lines, the aircraft struck and severed two wires which crossed its path. It then yawed sharply and collided with the other wires, before impacting the ground in a steep nosedown attitude. During the ensuing short ground slide both the engine and the rubber fuel tank were torn out. The pilot later advised that he had been aware of the power lines, but had temporarily overlooked their presence.