The helicopter was on a training flight from Cork Airport. During the en route phase, in the vicinity of Ringaskiddy, Co. Cork, the Pilot felt vibration accompanied by low rotor Revolutions Per Minute (RPM) warnings. The Pilot broadcast a “Mayday” transmission to ATC and made a successful autorotation(5) into an agricultural field. There were no injuries. The Investigation found that the helicopter’s engine suffered a gross mechanical failure and the engine sustained substantial damage during the event.
(5) Autorotation: A procedure in which a helicopter rotor is driven solely by the relative motion of air acting on its rotor blades as the helicopter descends without engine power.