On July 31, 2001, at 1100 central daylight time, an Aero Commander S2R, N5551X, operated by Ice Spray Service, was destroyed on impact with terrain following an in flight collision with a power line. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 137 agricultural flight was not operating on a flight plan. The commercial pilot sustained serious injuries. The local flight originated from the Pierre Regional Airport, Pierre, South Dakota at approximately 1030. The pilot reported in a written statement, "Flight departed Pierre, S.D. airport about 10:30 AM to spray a field of sunflowers for insects, about 5 miles north of the Prierre Airport. This field has a power transmission line throught the field. The poles are over 200 feet high, so we fly under the wires. I was a little high and the rudder hit the line, tearing the rudder completely off and damaging the fin. I could not control the aircraft, so I shut it off and put it on the ground. It was heading for a house, but by putting it on the ground, I missed the house. it happened about 10:50 AM after several passes under the wire. I escaped with a sprained ankle.