What happened
On 21 June 2025, a Bensen B8M Gyrocopter, registration EI-BSG, was performing local circuits at ILAS Field in Taghmon, Co. Wexford. Shortly after departing from runway 18, the aircraft climbed to approximately 200 feet before entering a left-hand turn. During this maneuver, the engine suffered a sudden loss of power. The pilot attempted to use the throttle, but the engine failed to respond, necessitating an immediate forced landing in a nearby agricultural field.
Due to the low altitude and insufficient airspeed to flare the aircraft, the Gyrocopter struck the ground heavily and bounced before coming to rest on its side. The impact caused substantial damage to the airframe, including the main rotor blades, the vertical stabilizer, and the propeller. The pilot, who was the sole occupant and wearing a flight suit, helmet, and four-point harness, was able to exit the aircraft without injury.
The investigation
Investigators examined the engine, fuel system, and ignition components to determine the cause of the power loss. While the wreckage showed a detached ignition coil wire and a partially dislodged distributor cap, photographic evidence from the takeoff roll confirmed these components were secure prior to impact. Subsequent testing demonstrated that the engine could start and run smoothly with these parts refitted.
Regarding fuel, investigators found approximately 7 liters of fuel remaining in the tank, ruling out fuel exhaustion. The fuel itself appeared clear, though laboratory analysis noted an increased water content. The investigation also considered the possibility of carburetor icing, noting that the aircraft utilized MOGAS (unleaded automotive gasoline), which is more susceptible to ice formation than standard aviation gasoline.
Findings
- The engine power loss was not caused by technical defects in the ignition or fuel delivery systems.
- The aircraft was not running under power at the moment of impact.
- Carburetor icing is considered a possible cause of the engine power loss, as the ambient temperature and dew point conditions supported the formation of ice.
- The use of MOGAS and the presence of increased water content in the fuel may have heightened the risk of icing.
- The Gyrocopter lacked a carburetor heating system, leaving the pilot with no way to mitigate the threat of ice formation.