News release

Today, the Transportation Safety Board of Canada (TSB) released its investigation report (A23P0040) into the fatal accident involving an Airbus AS 350 B3 operated by Mustang Helicopters Inc., at Smithers Airport, British Columbia. The occurrence took place during maintenance ground run operations conducted to balance the helicopter’s tail rotor drive shaft.

On May 6, 2023, the helicopter underwent maintenance to balance the tail rotor drive shaft which required its rotor system to be run at nearly full RPM. During the third maintenance ground run, it entered an uncommanded rotation. The pilot responded by moving the engine control to IDLE, shutting off the fuel, and applying the rotor brake. The helicopter came to rest after it rotated approximately 540°. Two maintenance staff members were standing on the ground near the helicopter’s left cargo door monitoring the balancing equipment. They were both struck by the tail rotor; seriously injuring one and fatally injuring the other.

The investigation found that after the first maintenance ground run, the pilot abbreviated the operator’s checklist to expedite operations. In doing so, important steps were not completed, which left pressure in the hydraulic system and the right anti-torque pedal in a fully forward position, which went undetected before the third maintenance ground run. The pilot was not expecting the helicopter’s rapid rotation and was looking down when the rotation began. His response to the rotational force (yaw force) was insufficient to prevent the helicopter from rotating quickly.

As this type of maintenance was viewed as routine and repetitive, the pilot’s attention was split between the maintenance ground run operations and his cellphone, which was connected to a Bluetooth earpiece. The TSB has previously identified risks associated with the use of cellphones in accidents. It is well understood that electronic devices can divert attention from activities that are necessary for safe operations, and currently there are no regulations in Canada that prohibit the use of cellphones in the cockpit.

Following this occurrence, the operator strengthened safety practices by updating maintenance procedures and implementing a new distraction policy which includes stowing electronic devices. Hazard assessments and safety briefings were revised, and a new standard operating procedure for maintenance ground runs was added to the company operations manual.

See the investigation page for more information.