Accident Details
On a daylight operation at 1300 Atlantic Daylight Time, a Bell 407 helicopter (registration C-FTJU, serial number 53331), operated by Universal Helicopters Newfoundland Limited, was conducting slinging operations approximately 4 nautical miles southwest of Wabush, Newfoundland and Labrador. The helicopter was lifting a 2300-pound drill tower on a 90-foot long-line. While approaching the drill base frame at about 220 feet above ground level and 36 knots indicated airspeed, a loud bang and puff of smoke emanated from the engine exhaust. The helicopter immediately lost engine power, experienced a rapid drop in main rotor speed (NR), and yawed left. The pilot released the drill tower before the helicopter struck the terrain about 9 seconds after the power loss. The pilot, the sole occupant, sustained minor injuries and exited the aircraft. The helicopter was substantially damaged, and the 406-megahertz emergency locator transmitter activated upon impact. No post-crash fire occurred.
History of the Flight
The helicopter had begun slinging operations at approximately 0917. At about 1300, it picked up the drill tower. As it approached the drill base, the power loss occurred. The pilot maintained collective position for about 4 seconds and then fully raised the collective. The helicopter collided with terrain after a left turn and rapid descent.
Investigation Findings
The Transportation Safety Board of Canada investigated the occurrence. The investigation determined that the third-stage turbine wheel failed due to the overstress extension of high-cycle fatigue cracks in the blade trailing edges, in a manner consistent with a known pattern, resulting in a loss of engine power. The engine power loss occurred at an altitude from which a safe landing could not be assured, leading to minor injury and substantial helicopter damage.
Risk Factors Identified
Rolls-Royce Corporation has not identified the specific engine operating conditions causing tensile residual stresses at the blade hub trailing edges, leading to a continued possibility of engine failure and increased risk of injury and helicopter damage. Additionally, a delay in carrying out required actions to maintain rotor speed following an engine power loss increases the risk of injury and damage. The pilot was not wearing a flight helmet, and while no head injuries were sustained, the investigation noted that helicopter pilots not wearing helmets are at higher risk of head injuries in a crash.