Accident Sequence
On a clear afternoon with calm winds and 15°C temperature, an MD Helicopters MD500D helicopter (registration C-GWPQ, serial number 700755D) departed Terrace Airport, British Columbia, at 1559 Pacific daylight time to retrieve a geological survey crew from a mountain site 35 nautical miles northwest. The pickup point was on a 25-degree slope within a bowl-like cirque. The pilot conducted a toe-in procedure due to the slope steepness. During the attempt, a loud bang was heard, and the helicopter dropped tail-low, then entered an uncontrolled right turn and struck terrain 30 yards downhill from the pickup point.
Impact forces ruptured fuel cell compartments, causing a fire. The geological survey crew assisted the pilot from the burning helicopter and provided emergency first aid until an air ambulance arrived at 1840. The pilot, the sole occupant, was seriously injured. No persons on the ground were injured. The helicopter was destroyed by impact and the intense post-crash fire.
Investigation Findings
Approximately 50% of the helicopter by weight was destroyed in the fire. Detailed examination of the main transmission, rotor head, engine, and accessory gearbox found no mechanical defects. Main rotor blades were broken at the root and severely damaged; impact marks on blade grips indicated a positive pitch position at impact. No ground scars at the pickup site from a main rotor blade strike were found.
During the crash, the last 12 inches of the tail boom, most of the tail rotor drive shaft, the tail rotor, and the tail rotor gearbox detached and landed 32 yards away, the only components not damaged by fire. Tail rotor blades were intact but showed evidence of strike with terrain. The tail rotor drive shaft exhibited torsional twist and fracture at the forward end, indicating sudden stoppage under power. No mechanical anomalies were found in the tail rotor gearbox or blades. Dried mud extended from blade tips to approximately 80% of the blade span; mud splatter was also on vertical stabilizers and T-tail. Ground scars aft and right of the pickup site were consistent with a tail rotor strike.
Flight controls were examined to the extent possible; no anomalies were found, but most cockpit controls were consumed by fire. The engine was disassembled and examined; no anomalies were found in fuel components, fuel control unit, governor, fuel pump, turbine, compressor, or accessory gearbox. Fire damage precluded determination of engine rotation. Insufficient fuel remained for analysis. The pilot did not recount any engine difficulty.
Weight and balance calculations showed the center of gravity was 103.98 inches aft of datum, within limits.
Rescue Timeline
The helicopter operator raised concerns about delays. The TSB established a timeline: At approximately 1645, the survey crew started calling for assistance via satellite phone but calls did not get out. At 1712, using radio and satellite, they contacted Quantum Helicopters and requested immediate medical assistance. Quantum contacted the Provincial Air Ambulance Coordination Centre (PAACC) directly. Joint Rescue Coordination Centre (JRCC) Victoria was notified at 1714 but did not dispatch resources as local actions appeared adequate. Quantum had a B206 helicopter ready but could carry only one medic; two were required. At 1724, PAACC contacted Canadian Helicopters in Terrace for a larger helicopter. By 1800, a suitable landing area was verified, a Canadian Helicopters Astar was ready at Terrace, and medics were en route. By 1820, the Astar was en route to the site, arriving at 1840. At 1900, with the patient on board, the Astar departed and arrived at Terrace hospital at 1930.
The TSB concluded that despite some delay in initial requests and organizing medevac, the combined delay was not unreasonable given the remote location. Canadian Forces search and rescue resources were approximately two hours away; local resources completed the rescue faster.
Additional Analysis
Trim actuator motors indicated a near full-forward cyclic trim position. The pilot did not report any longitudinal control problem, making a trim runaway unlikely. No evidence suggested that a previous hard landing and rollover (June 2004) or subsequent repair contributed to this accident. Fire damage precluded determination of engine rotation, but main rotor blade damage and pilot observations indicated the engine was producing power at impact.
The tail drop and tail rotor impact marks to the right and rear, indicating counter-clockwise yaw, are consistent with a reduction in engine torque. Once the tail rotor contacted ground, the drive shaft sheared and the helicopter yawed clockwise rapidly. Control would have been difficult to regain; given the terrain, a successful emergency landing was not possible. Because the helicopter flew a short distance after the tail rotor strike, some degree of engine power was likely available. The reason for the loss of control and tail drop could not be determined due to fire damage. Insufficient physical evidence explained the loud bang before the tail strike.