Skipped checklist, pilot distraction in fatal Smithers helicopter accident: TSB

A photo from the Transportation Safety Board report showing the helicopter shortly after the "uncommanded rotation" during maintenance operations at Smithers airport on May 6, 2023. Photo by Smithers RCMP/Transportation Safety Board

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A helicopter pilot failed to complete key checklist steps during a maintenance ground run at a Smithers hangar and was caught off guard when the aircraft suddenly spun, killing one worker and injuring another, the Transportation Safety Board says.

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The Airbus AS350 helicopter operated by Mustang Helicopters was undergoing maintenance at Smithers Airport on May 6, 2023. As part of the work, the helicopter had to be in “flight idle” which required its rotor system to run at full r.p.m. while staying on the ground.

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The crew — a pilot inside the cockpit and two aircraft maintenance engineers outside the helicopter — had completed two runs without incident. On the third, the helicopter started an “uncommanded rotation” to the right.

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The pilot had his head down at the time, but quickly idled the engine and applied the overhead rotor brake when he realized the helicopter was rotating, said the report. The aircraft did 1½ complete rotations on the ground before coming to a stop.

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The two engineers standing near the helicopter’s left cargo door tried to move to avoid the spinning copter, but were hit several times by the tail rotor. One died. The other was seriously injured and was flown to hospital in Prince George where he had several surgeries.

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The federal transport agency’s investigation found that the pilot’s attention was not fully focused on conducting the maintenance operations, which were viewed as routine and repetitive. 

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The pilot shortened the checklist to expedite operations, it said in its report, released Wednesday. “In doing so, important steps in the checklist were not completed, leaving the right anti-torque pedal in a fully forward position, which went undetected for the third maintenance ground run operation.”

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It also said the pilot’s feet were “lightly resting” at the bottom of the anti-torque pedals or not on them at all. “Given the position of the pilot’s feet, the pilot’s response to the yaw force was insufficient to prevent the helicopter from beginning to rotate quickly to the right.”

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The investigation found no defects with the helicopter’s tail rotor system or related components that would have affected the normal functioning of the aircraft.

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The report also noted the pilot’s attention was split between the maintenance operations and his cellphone, which was connected to a Bluetooth earpiece in his left ear. He was listening to music and in between operations was monitoring scores of a live game.

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The TSB has previously identified risks associated with cellphone use in accidents, but there are no regulations in Canada that prohibit the use of cellphones in the cockpit.

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After the incident, Mustang Helicopters changed its maintenance procedures to require the aircraft maintenance engineer to be inside the helicopter during maintenance ground run operations and purchased wireless communication systems for the pilot and engineer to communicate. The company also implemented a new policy that included stowing personal electronic devices.

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