Final Report: Unsecured pack likely caused fatal crash

 - March 31, 2010, 8:16 AM

Eurocopter AS350B2, Chickaloon, Alaska, April 15, 2008–The NTSB blamed the fatal crash on loss of engine power due to an overspeed of the helicopter’s engine, precipitated by the inadvertent movement of the fuel-flow control lever by the passenger. The AS350, operated by ERA Helicopters under Part 135, was transporting telecommunications technicians to remote sites. After dropping off one technician, the helicopter flew to another location and picked up a technician and his stepson near a highway rest area.

A witness watched the helicopter take off and make a steep descent into a nearby ravine but did not see any impact. When the helicopter did not return to pick up the first technician, a search was launched but it was hampered by a snowstorm. The next morning, approximately 24 hours after the accident, the wreckage of the helicopter was found less than a mile from the rest area. The teenage boy, who had been in the left front seat, was suffering from head injuries and hypothermia. The pilot and the three technicians in the back seat were found dead.

Examination of the wreckage found free-turbine blade shedding consistent with an engine overspeed, while the rotor system and drive train exhibited impact damage. In the cockpit, the floor-mounted fuel-flow lever was found in the forward emergency position while the emergency fuel-shutoff lever was in the aft shutoff position, indicating likely interference from either the passenger’s foot or unsecured baggage. The helicopter’s acrylic left chin bubble was found three feet from the helicopter’s nose, along with a backpack belonging to the boy. All other baggage and cargo was securely stowed.

According to the manufacturer, inadvertent movement of the fuel flow lever–which is mounted on the floor near the front passenger’s right foot– can cause the engine to overspeed within seconds. Several previous accidents have been blamed on passenger interference with the control, the location of which makes it susceptible to accidental contact and movement by passengers, said the Board. A contributing factor to the accident was the pilot’s failure to properly secure the passenger’s backpack.

The helicopter was equipped with a commercial satellite tracking system that allowed the operator to monitor the helicopter’s movements. According to the satellite data, the helicopter’s final flight lasted less than one minute. The operator’s personnel at its Louisiana headquarters did not monitor Alaska flights, and no known “overdue” alarm was sent. The Board ruled that a factor contributing to the severity of the occupants’ injuries was the helicopter operator’s failure to properly monitor its satellite flight following system and to immediately institute a search once the system reported the helicopter was overdue.