News story
AAIB report: Eurocopter EC135, serious incident during maintenance flight
Eurocopter EC135 (G-POLA) incident during maintenance flight, Northumberland.
During a maintenance flight to adjust speed, main rotor rpm varied between its maximum and minimum continuous limits. A mechanical stop within the speed control system had failed in such a way that main rotor speed could not be controlled accurately, putting the helicopter at significant risk. The pilot’s actions prevented rotor speed exceeding its limits and a more serious outcome. The manufacturer and operator have taken safety action regarding the conduct of airborne engine speed adjustments.