History of the Flight
The helicopter departed Stewart Airport at approximately 0943 Pacific Daylight Time with a pilot and two passengers. It flew to a geological exploration site 14 nautical miles north of Stewart, adjacent to the Nelson Glacier. Flight tracking data ceased at 1004 PDT. No further voice communications were recorded.
Accident Sequence
After performing a left-skid toe-in landing on a mountain ledge at 5100 feet above sea level, one passenger exited via hover exit to retrieve a climbing rope. The helicopter lifted off, backed away, and then landed again to pick up that passenger. At 1001, the helicopter lifted off with both passengers and maneuvered slowly across the mountain face. The last GPS position at 1004 indicated a landing 760 feet above the rope pick-up location. The wreckage was discovered six hours later strewn down the steep mountainside. There were no survivors. No fire occurred.
Data Analysis
The investigation retrieved data from handheld cameras, a portable GPS, and the onboard GPS tracking system. The engine control unit (ECU) showed a gradual power reduction followed by a sudden drop in main-rotor rpm. A torque spike to 150% was consistent with a major rotor strike. The subsequent divergence of main-rotor speed (decrease) and power turbine speed (increase) indicated a severed driveshaft. No helicopter system failure was identified.
Findings
While working in close proximity to steep terrain, the helicopter's main-rotor blades made contact with terrain, causing a subsequent loss of control and collision with terrain. The emergency locator transmitter (ELT) antenna was damaged, preventing signal reception. The GPS tracking system did not send an automatic emergency notification. Ground personnel did not initiate the overdue-aircraft response plan in a timely manner, and the Joint Rescue Coordination Centre was not notified. Occupant restraints in the rear cabin were not fastened.