On June 10, 1998, at 1200 central daylight time (cdt), a Bell 47G, N73284, flown by a commercial helicopter pilot collided with powerlines during an aerial application flight in Le Center, Minnesota. The pilot received serious injuries and the helicopter was destroyed. Visual meteorological conditions prevailed and no flight plan was filed for the local 14 CFR Part 137 flight. The flight originated in Le Center, Minnesota. The pilot reported that while spraying "ditch banks" the helicopter contacted a wire which was embedded in heavy vegetation. He continued to report "The wire broke & fouled the rotor blades. Then the aircraft & I hit the ground." An Inspector from the Federal Aviation Administration Minneapolis, Minnesota, Flight Standards District Office reported the pilot was spraying along a creek bed when the accident occurred. The wire which was contacted was approximately 20 feet above the terrain (creek bed) and the poles on which the wire was strung were hidden by vegetation. The inspector stated the pilot was aware of the wire, but did not see it during the swath run. He stated the wire twisted around the transmission and main rotor blades.