NTSB Factual Report

On June 11, 2014, about 1140 Alaska daylight time, an Airbus/Eurocopter AS350 B3 helicopter, N356EV, sustained substantial damage as a result of a main rotor over-speed, followed by a ground resonance event during the engine start sequence at the Merrill Field Airport, Anchorage, Alaska. The helicopter was being operated as a visual flight rules (VFR) cross-country ferry flight under Title 14, CFR Part 91, when the accident occurred. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. Of the three people aboard, the first pilot, seated in the left seat, the second pilot, seated in the right seat, and a passenger, were not injured. The flight was en route to Gulkana Airport, Alaska, the flight's first planned fuel stop.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 13, the first pilot, a certificated flight instructor, reported that he had been hired to ferry the recently purchased helicopter to Georgetown, Texas. He added that he was providing AS350 B3 helicopter transition training to the second pilot, who was also the new owner of the helicopter. The first pilot reported that after having some difficulty starting the helicopter, he asked for assistance from a mechanic and another pilot. He said that while talking with another pilot on a cell phone about the correct starting procedure, the second pilot exited the helicopter, and a mechanic boarded the helicopter and sat down in the right seat. Once the helicopter was successfully started, the mechanic disembarked, and the second pilot again boarded the helicopter, and sat down in the right seat.

The first pilot noted that while the helicopter was operating at flight-idle, the yellow "TWT.GRIP" light was illuminated on the annunciator panel, and he instructed the second pilot to slowly advance the collective-mounted throttle twist grip to the open position until the light went out. He said that as the second pilot began to advance the throttle to the open position, the engine immediately went to a very high RPM, and the helicopter began to shake violently, and it subsequently rotated about 240 degrees to the left. He said he did an emergency engine shutdown, and then all the occupants exited the helicopter.

The helicopter's fuselage and main rotor drive system sustained substantial damage.

The helicopter was equipped with a Turbomeca Arriel 2B series engine, equipped with a single channel, Full Authority Digital Engine Control (FADEC) fuel control system. An NTSB postaccident inspection is pending.