The Transportation Safety Board of Canada (TSB) released its investigation report into the Airspan Helicopters’s Bell 212 loss of control and collision with terrain that occurred on Bowen Island, British Columbia (BC) in March 2021.
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The investigation found that environmental conditions and the helicopter’s system limitations led to the occurrence.
On 05 March 2021, the Bell 212 helicopter, with two pilots on board, was travelling from Sechelt, BC, to Cypress Provincial Park, BC.
During the cruise portion of the flight, the helicopter entered wind shear and experienced a sudden loss of control. After the crew regained control of the helicopter, the number 2 engine experienced an uncommanded in-flight shutdown and the flight controls became very hard to manipulate. A location on nearby Bowen Island, BC, was selected for an emergency landing.
During the descent, the helicopter began a rapid rotation to the right, which the pilots were unable to arrest. After several rotations, the helicopter collided with trees and came to rest on a rocky ridge on the northwest corner of Bowen Island. Both occupants received serious injuries.
The helicopter was substantially damaged.
The investigation found that at the time of the occurrence, the environmental conditions were conducive to severe mechanical turbulence, lee waves, and low-level wind shear along the helicopter’s flight path in the vicinity of Bowen Island.
The pilots were aware of the forecasted weather, low-level wind shear, and mechanical turbulence, but decided to continue with the day’s planned flights based on improving weather forecast later in the day, the desire to complete the operational flight, and the observation that other aircraft were operating around the Sechelt Aerodrome.
The helicopter entered an area of severe turbulence that led to a loss of control, that resulted in excessive flapping of the main rotor blades. As a result, the main rotor blades contacted and severed the tail rotor driveshaft, causing a loss of tail rotor thrust and yaw control.
The helicopter’s extreme attitude during the initial loss of control likely caused the hydraulic system to malfunction, the number 2 engine to shut down in flight, and the number 1 engine to reduce fuel flow (resulting in less power), which subsequently reduced the main rotor speed.
As the helicopter slowed for the emergency landing, yaw control was lost due to the absence of tail rotor thrust, and the helicopter collided with the terrain.
Following the occurrence, Airspan Helicopters temporarily suspended all operations, completed an internal safety investigation, and took several actions to mitigate future occurrences. ■