Canada’s Transportation Safety Board (TSB) has tied the fatal crash of a 1979 Bell 212 on June 28, 2021, to the failure of a main rotor blade hub strap retaining pin, resulting in the in-flight breakup of the helicopter. The aircraft, operated by Yellowhead Helicopters, had accumulated 29,627 fight hours when it crashed near Evansburg, Alberta while supporting firefighting operations. The sole occupant pilot was killed and a post-impact fire destroyed the helicopter.
The twin-bladed helicopter was approaching a landing zone to pick up a group of firefighters when one main rotor blade separated from the rotor head assembly. The second rotor blade and rotor head assembly then broke free from the helicopter and the helicopter crashed.
The TSB determined that the failed pin was manufactured from weaker steel than that in the design specification. The quality control systems at the part’s manufacturer did not detect the error, thereby releasing substandard pins into the supply chain.
Following the accident, Bell issued four alert service bulletins requiring a review of the aircraft’s technical record to determine if any non-conforming main rotor hub strap retaining pins were installed on model 204B, 205, 205B, and 212 helicopters and for the replacement of any non-conforming pins. Transport Canada issued an emergency airworthiness directive (CF-2021-23) mandating compliance with the Bell Textron Inc. alert service bulletins, as did the FAA and EASA.