What happened
During a refresher course in seaplane flying, a private pilot was conducting the fifth takeoff of the day. As the aircraft lifted off from the lake, the pilot at the controls observed that there was no aileron control available. The flight instructor assumed control of the aircraft; however, the airplane rolled to the right and impacted the water. The aircraft subsequently sank to a depth of 60 feet. There were no injuries reported in the accident.
The investigation
Examination of the wreckage revealed that a turnbuckle had separated from the right aileron cable. This turnbuckle was not safety-wired. At the time of the accident, the aircraft had accumulated approximately 55 hours of operation since its last annual inspection. Maintenance logs for the engine indicated that the left and right aileron control cables had been removed and replaced, and the aileron carry thru cable had been replaced in accordance with specific manual instructions. The log entry concluded with a certification that the aircraft had been inspected and determined to be in an airworthy condition.