What happened
A Helio H-295 Super Courier, registered as C-FOMI, was operating a flight from Smithers, British Columbia, to Calgary, Alberta, via Fort St. James. After picking up a passenger at Fort St. James, the aircraft was en route when a witness in the Hugh Allan Creek area observed the aircraft spiralling toward the ground with debris trailing behind. The witness reported hearing two loud cracks and seeing the right wing detach from the airframe. The aircraft crashed in a steep, wooded area approximately 37 nautical miles southeast of Valemally at roughly 1600 PDT. The impact occurred in a vertical descent, and both occupants were fatally injured.
The investigation
The investigation examined the wreckage, which was found at an elevation of approximately 4500 feet. Investigators recovered the right wing 575 meters from the main wreckage and found fuel cell debris nearby. The investigation established that the aircraft's slats had deployed violently before being torn away, and the flaps were ripped from their attachments. Examination of the right wing main spar revealed it had failed due to an overload.
Maintenance records showed the aircraft was within its weight limits and had been maintained according to regulations, though the aircraft was operating under a supplemental type certificate (STC) that increased its maximum gross weight. Investigators also noted that the airspeed indicator had not been updated to reflect the new, lower speed limits associated with the increased weight, potentially providing misleading information to the pilot. Additionally, fretting corrosion at the lower wing attachment points indicated that the aircraft had previously experienced loads exceeding its design limits.
Findings
- The aircraft had previously exceeded its limit load factor, which compromised the integrity of the ultimate load factor.
- The aircraft likely encountered a strong gust that exceeded the ultimate load factor during cruise, leading to the failure of the right wing main spar.