On August 1, 2022, at 1420 central daylight time, an Air Tractor Inc AT-301, N4326S, was destroyed when it was involved in an accident near Lamoni, Iowa. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot stated that the accident flight was the sixth or seventh aerial application flight that he performed on the day of the accident. He stated that the run-up and takeoff for the flight were normal. After takeoff, he turned west toward the field and noticed a lack of performance. The pilot turned the airplane toward the north and lowered the airplane’s nose to gain airspeed. He adjusted the propeller, engine power, and flaps, but was unable to maintain altitude. The pilot dumped the load of aerial applicant, and airplane then impacted trees and terrain. The airplane was destroyed by impact forces and postcrash fire. The pilot stated that all engine instrument indications were normal, the engine speed was 2,250 rpm, and the manifold pressure was 37 inches at the time of impact, Postaccident examination of the engine revealed that the rear accessory housing, and all attached accessories, sustained impact and post-crash fire damage. Examination of the engine drive gears leading into the accessory drive housing were found intact and did not display failure. The impeller housing and impeller shaft seal did not display failure. There was no evidence of oil leakage into the impeller housing. Drive gears from the engine into and including the impeller drive did not display failure. There was no abnormal play of the impeller shaft and its bearing. Rotation of the crankshaft drivetrain confirmed continuity. The cylinders exhibited normal features with no corrosion, scoring, or excessive wear.