Accident Details
The Bell 206L (LongRanger) helicopter, serial number 45019 and registration C-FRCL, was operated by Quantum Helicopters Limited. The accident occurred at Legate Creek, just north of Terrace, British Columbia. At approximately 1030 Pacific daylight time, the pilot began long-line operations to move a drill rig at about 4200 feet above sea level on a steep hillside. The first two lifts were completed without incident. The weather was cloudy with rain showers, calm winds, and a temperature of about 12°C.
Sequence of Events
Upon lifting the third load, the helicopter descended into the valley before climbing slowly. It required two orbits to gain sufficient altitude to approach the landing area. When the load was about three feet above the drill deck, the helicopter descended rapidly, causing the load to strike the deck hard. As ground crew attempted to unhook it, the load rose abruptly back into the air, then slammed onto the deck again as the helicopter fishtailed. The load was lifted again, and the helicopter began to spin with its tail bent. The load remained attached, became lodged in trees, and the spinning helicopter descended in an arc, crashing into the cliff. It ended upside down. There was no fire. The emergency locator transmitter broke free and emitted a signal for about 15 hours.
Analysis and Findings
Examination showed no evidence of progressive failure or weather-related problems. The hard landing of the load was consistent with the helicopter sinking rapidly as speed decreased due to limited performance, as predicted by hover-out-of-ground-effect (HOGE) charts. The main rotor blades struck the tail boom in a hover, a regime where contact is highly unlikely. The deck support did not break as an initiating factor; the tail boom was intact before being struck. The analysis identified collective bounce as the most probable cause of the rotor strike. Factors included the three-foot drop of the load, the pilot leaning out the right door with left arm extended to the collective (susceptible to uncommanded movement), lack of built-in collective friction, long-line stretch aggravating vertical oscillations, and flexing of the main rotor blades. The load's rapid vertical movements indicated uncommanded power changes.
When the tail boom was struck, tail rotor drive and control were lost, causing the helicopter to spin to the right. The pilot could not stop the spin; reducing throttle or gaining forward speed might have helped, but the pilot lost control, and the helicopter collided with terrain. The reason the pilot did not release the external load was not determined; possibilities include electrical release not attempted or hook angles preventing release. The pilot's upper body was unrestrained, and the door was removed, increasing injury risk upon impact.
Findings as to Causes and Contributing Factors
The helicopter was operating at a weight that, when forward speed was reduced, caused rapid descent and hard load impact. The hard landing, combined with pilot body position, long-line stretch, and low collective friction, initiated collective bounce, causing main rotor blades to strike the tail boom. Loss of tail rotor drive and anti-torque control led to an uncontrolled spin and collision with terrain.