What happened
While transporting rock core samples from Meadowbank Camp to Baker Lake, Nunavut, a Hughes 500 helicopter experienced two distinct vibration events during level cruise flight at 500 feet. The first event caused the cyclic control to vibrate, followed shortly by a second event that caused vibrations in the anti-torque pedals. Despite normal engine indications, the pilot opted to perform a precautionary landing approximately 26 nautical miles north of Baker Lake.
As the aircraft approached the surface, the pilot lost visual reference due to blowing snow and whiteout conditions. During the touchdown, the tail stinger and the right skid contacted the snow, causing the helicopter to roll onto its right side. The resulting rollover caused extensive damage to the main-rotor blades, the rotor head, and various control components. The uninjured pilot successfully shut off the fuel and evacuated the aircraft. Although the pilot briefly activated the emergency locator transmitter (ELT), the signal was short-lived, though it allowed the Rescue Co-ordination Centre to locate the site.
The investigation
Investigators examined the wreckage and the mechanical systems of the aircraft. While the main-rotor system sustained heavy damage from the impact, the engine and fuel systems were found to be in good working order, with no evidence of contamination in the Jet-B fuel. The tail-rotor drive components remained intact, though the tail boom was bent and the tail-rotor blades showed evidence of contacting the ground during the rollover.
Technical analysis of the tail-rotor blades suggested that the outward bending was a result of the blades striking the snow-covered surface rather than an in-flight failure. Investigators also looked into the failure of the survival kit flares, which failed to ignite when the pilot attempted to signal rescuers. It was noted that the flares were near their expiration date and may have suffered from propellant compaction due to prolonged exposure to helicopter vibrations.
Findings
- The pilot lost visual reference in blowing snow during the landing, leading to a dynamic rollover upon touchdown.
- Foreign object damage was identified on the tail rotor.
- Extensive damage to the main-rotor assembly prevented a definitive determination of the cause of the initial in-flight vibrations.
- The pilot did not adhere to company procedures regarding the filing of a written flight itinerary or the continuous operation of the ELT following the accident.
- The survival kit flares were ineffective due to failure to function as intended.
Safety action
- The operator implemented additional training for pilots to ensure compliance with flight-following and flight-planning procedures.
- The company upgraded its safety systems to prioritize flight planning with local flight service stations and provided pilots with expanded access to company procedures via the internet.
- The operator acquired satellite phones for use in areas with limited communication.
- The survival kit flares were replaced with a different manufacturer's product.