AAIB investigation to EC120 B Colbri, G-RCNB
Helicopter rolled onto its side after lift-off, Enniskillen Airport, County Fermanagh, 25 June 2019.
Summary:
The pilot had planned a flight from Enniskillen, St Angelo Airport, to a private site at Frosses in Donegal, Ireland. The helicopter was parked on the apron adjacent to the fuel installation where it had just been refuelled to full tanks. Having completed all the pre-start checks from the checklist and carried out a normal start, the pilot performed the pre-takeoff checks and raised the collective pitch lever. He led with right yaw pedal but, as the helicopter became light on the skids, it started to yaw to the left. Due to the close proximity of the fuel storage tanks, he applied left cyclic control to move the helicopter to the left away from them, but the helicopter continued to yaw to the left. After yawing through 360°, the helicopter lost height with the left skid contacting the apron. The helicopter rolled about the left skid and the main rotor contacted the ground and debris was scattered over a wide area. The helicopter continued to yaw through another 90° about the tail before rolling onto its right side. The pilot shut off the fuel before applying the rotor brake and was able to leave the helicopter unassisted through the left door. The airport Rescue and Fire Fighting Service attended the scene immediately and applied a foam blanket to the wreckage.
Over the preceding weekend the pilot had been flying a Robinson R44 helicopter on which the main rotor blades turn anticlockwise when viewed from above. The EC120 main rotor blades turn in the opposite direction ie clockwise when viewed from above. The pilot was aware of this difference and the way it affects the use of the yaw pedals: raising the collective pitch lever in the Robinson requires increasing amount of left pedal to counter the rotor torque, but in the EC120 increasing amounts of right pedal are required. The pilot believed that during the initial phase of applying collective lever, he had used insufficient right yaw pedal, allowing the helicopter to yaw left, and the application of additional right pedal did not then reduce the yaw rate.
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