On July 6, 1998, at 1545 central daylight time, a Cessna T188C, N9957J, while conducting a swath run dispensing chemicals, the engine suffered a loss of power and the pilot initiated a forced landing, impacting the terrain 4.5 miles southeast of Austin Municipal Airport, Austin Minnesota. The commercial pilot received no injuries and the airplane sustained substantial damage. The airplane was being operated as a commercial flight under 14 Part 137 and performing aerial applications when the accident occurred. The flight originated from Austin Municipal Airport at 1515. Visual meteorological conditions prevailed and no flight plan was on file. The pilot said in his written statement that maintenance was performed on the throttle and mixture control about "noon" on the day of the accident. He said that he resumed aerial application work about 1300 and at 1544 suffered a loss of engine power. He initiated a forced landing from about 80 feet above ground level and impacted crops and the terrain during the touchdown. An inspection subsequent to the accident found that a cotter pin was left out of the throttle control and the castle nut had fallen off. The mechanic who performed the work made a written statement, in which he said, "I had it apart, and I think I just didn't safety it."