On October 13, 2003, at 0822 Pacific daylight time, a Rockwell International S-2R airplane, N7950V, collided with the ground during an aerial application near Lemoore, California. Machado Dusters, Inc., was operating the airplane under the provisions of 14 CFR Part 137. The pilot sustained serious injuries; the airplane sustained substantial damage. The flight departed a local dirt strip about 0810 for the local aerial application flight. Visual meteorological conditions prevailed, and no flight plan had been filed. In a written statement, the pilot reported that during crop dusting operations he was flying along the north edge of a field, spraying from west to east. About midfield, the airplane entered a steep bank to the right, and the right wing tip impacted the ground. The pilot did not know why the steep bank occurred. The Federal Aviation Administration (FAA) inspector interviewed the pilot. He stated that he was flying and looked toward the right wing "for some reason." Shortly thereafter, the right wing tip impacted the ground. No engine problems were reported. The inspector completed an on scene examination of the wreckage. Control continuity could not be established due to impact damage sustained in the accident sequence. Fuel was present at the site and there were no indications of a bird strike. The inspector reviewed maintenance records and they complied with current regulations.