On July 6, 1999, at 1240 mountain daylight time, a Weatherly 620B, N350WR, sustained substantial damage when it impacted terrain after takeoff from Runway 17 (2,400 feet by 120 feet, dry/turf) at the Timber Lake Airport near Timber Lake, South Dakota. Visual meteorological conditions prevailed at the time of the accident. The aerial spraying aircraft was operating under the provisions of 14 CFR Part 137 at the time of the accident and was not on a flight plan. The pilot, who was the sole occupant, reported no injuries. The flight was originating at the time of the accident. In a written statement, the pilot stated that the aircraft was loaded with 270 gallons of solution. The pilot stated that, during the initial takeoff roll, the aircraft seemed to accelerate normally and that the tail came off the ground where it normally would. After liftoff, the aircraft settled back down on the main landing gear about 3/4 of the way down the runway. The pilot stated that the airplane again lifted off and struck a fence. The pilot stated that he decided to continue and started to dump the load of chemicals that he was carrying. The aircraft then struck another fence and posts and came to rest in a road east of the airport. The pilot stated that he did not believe that there were any problems with the aircraft. In his statement, the pilot wrote, "... what I wish I would have done is taken off on the other runway or not have filled her quite as full." According to the South Dakota Airport Directory, the Timber Lake Airport has a second turf runway (Runway 12/30) that is 3,300 feet long and 150 feet wide. A weather reporting station, located 30 statute miles and 75-degrees magnetic from the accident site, was reporting calm winds, an altimeter setting of 30.19 inches of mercury, and a temperature of 79-degrees Fahrenheit. The Timber Lake Airport field elevation is 2,193 feet mean sea level. The density altitude was 3,680 feet.