Event Description
Upon approaching the airport, the pilot received landing instructions. Shortly thereafter, the pilot's radio transmissions abruptly ceased. Witnesses observed the aircraft suddenly nose over and descend into the water at a high rate of speed. The aircraft fragmented upon impact and immediately sank.
Maintenance and Flight Test
The aircraft had recently undergone maintenance that included the removal and installation of its wings, as well as the installation of an autopilot and electric trim. A flight test was conducted following this work. During the test, the pilot experienced a loss of control, and the aircraft pitched down in a manner similar to that described by witnesses to the accident.
Examination Findings
Examination of the upper stabilator pulley assembly revealed that the stabilator control cable had been working against the side of the pulley. The pulley was found fractured, and the cable had become wedged in the pulley. Additionally, the pulley had become wedged against the side of its support bracket. This action restricted stabilator movement.