What happened
The pilot refueled the aircraft and secured the gas cap before conducting four aerotow flights, each lasting fifteen minutes. During the fifth aerotow, as the aircraft was climbing, the pilot heard an object strike the windshield and noticed that the gas cap was missing. The pilot smelled gas fumes and signaled the glider pilot that immediate release was necessary. The glider was released, and the engine was shut off at 1000 feet AGL. The pilot then ditched the aircraft in a lake.
The investigation
The investigation focused on the loss of the gas cap during flight. The pilot reported hearing an object strike the windshield and seeing the gas cap missing. The pilot also smelled gas fumes, indicating a potential fuel leak or vapor release due to the missing cap.
Findings
The gas cap was lost during the aerotow, leading to fuel exhaustion concerns. The pilot's decision to release the glider and shut off the engine at 1000 feet AGL was a critical factor in the outcome. The ditching in the lake was a direct result of the fuel system compromise.
Safety message
Pilots should ensure that all access panels, including gas caps, are securely fastened after refueling to prevent loss during flight. Regular pre-flight checks should include verification of all external components.