What happened
On 26 July 2013, a Kolb Firefly, registration G-CEPN, was conducting a private flight in the vicinity of Westmill, Hertfordshire. During the flight, the pilot experienced a sudden, loud noise originating from the rear of the aircraft, immediately followed by a significant reduction in engine thrust.
In response to the loss of power, the pilot executed a forced landing. The landing itself was completed without further incident or damage to the airframe. Upon inspection of the aircraft following the touchdown, it was observed that the propeller had become detached from the engine.
The investigation
The investigation was based on the aircraft accident report submitted by the pilot. Examination of the aircraft revealed that the propeller shaft had failed, which directly led to the propeller departing the aircraft. Aside from the loss of the propeller and the shaft, no other damage was identified on the Kolb Firefly.
Findings
- The primary cause of the loss of thrust was the failure of the propeller shaft.
- The specific mechanism or underlying reason for the shaft failure could not be established because the shaft itself was lost during the event.