What happened
During a charter flight from Thunder Bay, Ontario, to Red Lake, Ontario, a Beech A100 experienced a sudden loss of pitch control immediately after rotation. The aircraft, operated by Thunder Airlines Limited, climbed to an altitude of approximately 500 to 700 feet before pitching up sharply. The crew attempted to push the control column forward to arrest the climb, but the aircraft failed to respond to the inputs. Following a stall warning, the aircraft rolled left and entered a steep nose-down descent.
As the aircraft approached the ground at a high rate of descent, the crew applied maximum power, which caused the nose to rise slightly just before impact. The aircraft struck the ground within the airport boundaries, traveling about 500 feet before coming to rest in a wooded area. While a fuel-fed fire broke out following the impact, airport emergency services extinguished it quickly. All five occupants—two pilots and three passengers—escaped the 0 injuries incident without harm, though the aircraft was destroyed.
The investigation
Investigators focused on maintenance work performed on the elevator and rudder controls during the weekend prior to the flight. To facilitate rudder removal, the primary and secondary pitch trim actuators had been disconnected from the airframe. The investigation established that the two bolts intended to secure the top of the actuators to the airframe were not properly routed through the actuator holes. Instead, the bolts only passed through the airframe attachment points, effectively squeezing the ends of the actuators against the airframe rather than securing them.
While the aircraft was properly certified and maintained according to regulations, the investigation revealed flaws in the maintenance process. The technician performing the installation was qualified but lacked experience with this specific task. Furthermore, the crew chief's inspection was found to be superficial; the inspection was conducted without using mirrors or tools to verify the internal assembly and was hindered by complacency. Although a control check was performed after the work, the system appeared to function normally until the aerodynamic loads during takeoff caused the improperly secured actuators to separate from the empennage.
Findings
- The stabilizer trim actuator's upper mounting bolts were incorrectly installed, failing to pass through the necessary actuator holes.
- During takeoff, aerodynamic loads caused the improperly attached actuators to disconnect from the airframe.
- The disconnection of the actuators resulted in the loss of pitch control via the flight controls.
- The inspecting crew chief failed to verify the correct assembly of the components.
- The maintenance technician did not use proper alignment tools, such as a centering punch or mirror, during the reinstallation process.