What happened
On 26 October 2009, a Thruster T600N aircraft, registered G-EVEY, was operating near Newtownards Airfield in Northern Ireland. During the flight, the propeller became detached from the engine. The incident was reported by the pilot via an aircraft accident report form.
The investigation
Following the occurrence, the AAIB conducted an examination of the engine components. Investigators focused on the interface between the propeller and the crankshaft. The investigation involved a detailed inspection of the hardware responsible for securing the propeller assembly to the engine.
Findings
Technical examination of the crankshaft revealed that the propeller flange mounting screws had suffered from extensive fatigue crack propagation. The investigation established that these screws eventually failed due to ductile overload, which directly resulted in the propeller detaching from the aircraft.