Canada鈥檚 Transportation Safety Board says the fatal crash of a British Columbia logging helicopter was caused when the chopper鈥檚 rotor system broke up mid-flight.

A final report from the board says that on Oct. 4, 2021, the pilot of the Kaman K-1200 dropped off a load of logs into Jervis Inlet on B.C.鈥檚 south coast, turned around to pick up another load, then crashed into the water and sank.

The K-1200 has rotors on either side of the fuselage and the investigation found a blade on the left rotor had collided with a blade on the right rotor.

Investigators say a fracture in one of the aircraft鈥檚 joints led to a 鈥渇atigue crack鈥� that progressed until a piece separated in flight, causing sudden vibrations and fluttering of the rotor blades, and failure of the left pylon structure, which allowed the blades to hit.

The final report says the TSB issued an air safety advisory to Transport Canada in 2023, saying there needed to be further examination of servo flap fractures on Kaman K-1200 helicopters, after at least two fatal crashes involving fatigue fractures and 鈥渃atastrophic failure.鈥�

It says Transport Canada responded that the United States Federal Aviation Administration is responsible for the airworthiness of these helicopters and Canada was satisfied with the current manufacturer instructions for continued airworthiness.