Occurrence
On May 13, 2014, a Héli-Boréal inc. Eurocopter AS 350 BA helicopter (registration C-FHPC, serial number 2395) was conducting a power-line vegetation encroachment inspection flight with a pilot and an observer. The flight surveyed a 25-kilovolt power distribution line adjacent to a service road leading to Hydro-Québec’s Sainte-Marguerite power dam. While completing a right turn in a valley, the pilot noticed a 315-kilovolt power transmission line crossing perpendicular to the flight path. The right turn was increased to avoid the transmission line, but one of the helicopter’s main rotor blades struck the lower wire. The resulting damage caused severe vibrations, making the helicopter difficult to control. During the approach to land in a small clearing under the 315-kilovolt transmission line, the helicopter’s skid gear contacted trees. The helicopter rolled to the left and fell approximately 50 feet through the trees, coming to rest on its left side in the snow.
Injuries and Damage
Both occupants sustained serious injuries yet were able to exit the aircraft. The helicopter was substantially damaged. There was no post-impact fire.
Emergency Response
The 406-megahertz emergency locator transmitter activated on impact. However, the Cospas-Sarsat International Satellite System for Search and Rescue did not receive a signal until 25 minutes after the accident. The accident occurred in daylight hours at 1020 Eastern Daylight Time.
Investigation
The investigation was classified as a Class 3 investigation. The investigation concluded that a lack of standard power line markings led to the helicopter colliding with the wires.