Accident Details
During takeoff from a field adjacent to an office building, a helicopter came into contact with one or two power lines. The lines caught on the left skid, pulling the helicopter to the left. The main rotor blades then contacted two power lines, cutting both. The pilot attempted to maintain control, but the helicopter rolled to the left and impacted the ground.
Pilot Observations
The pilot reported that the wires were invisible to him at the time of departure. He also stated that there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.
Damage Assessment
A postflight inspection revealed substantial damage to the fuselage, main rotor blade system, tail boom, and tail rotor blade system.
Pilot Recommendation
As a safety recommendation, the pilot advised: "Best to walk the entire departure path, look for poles, wires, and guy wires prior to departure, especially with trees present, and a dark day which conceals the presence of wires. Don't get locked into one departure route. Turn the cellphone off when evaluating sites, and look 360 degrees."
Additional Information
Robinson Helicopter Company Safety Notice SN-16, titled "Power Lines Are Deadly" (revised June 1994), discusses wire strike mitigation techniques. The notice states that flying into wires, cables, and other objects is the number one cause of fatal accidents in helicopters. It advises pilots to watch for towers, fly directly over towers when crossing power lines, allow for smaller grounding wires, constantly scan for towers, and maintain at least 500 feet AGL except during takeoff and landing.