Crash of a Rockwell Aero Commander 500 in Mason City

The airplane was in a normal appearing climb after takeoff when it pitched up to a 70° to 80° attitude, stalled, dropped the right wing, then leveled the wings and hit the ground in a near-flat attitude. The weight and cg were within limits. No preimpact problems were found that could cause an inadvertent pitchup. Pilot's only memory is that he couldn't get the control column far enough forward to stop the pitchup. The pilot's seat was found in the full forward position with the right locking pin in the locking hole and the left pin 1/4th of an inch forward of the front locking hole. There were no visible marks on either of the locking pins. Deep scratches were found on the sides of the rail where the seat attachments normally slide back and forth when the seat is adjusted. Exam of the outboard side recessed surface near the aft end disclosed what appeared to be a fresh scratch. The pilot, sole on board, was seriously injured.