What happened
A charter flight operated by Propair, involving a Swearingen SA226-TC with 13 people on board, was traveling from La Grande Rivière to Puvirnituq, Quebec. During the daylight landing on a gravel runway, the aircraft experienced a sudden leftward veer immediately after the nose gear made contact with the surface.
The co-pilot, who was flying the aircraft, attempted to correct the drift using full right rudder and by reducing the throttles to ground idle. When the pilot-in-command took control, he found the aircraft continuing to drift left despite significant right rudder input. In a final attempt to regain control, the pilot engaged the nosewheel steering PARK button and applied full reverse thrust. However, the aircraft turned 90 degrees relative to the runway centerline, exiting the runway and crashing at the bottom of a 6-foot embankment. The impact caused the nose and main landing gear to separate from the airframe. One passenger sustained minor injuries, and all occupants evacuated through emergency exits after the main door became jammed.
The investigation
The investigation examined the aircraft's nosewheel steering system, which uses a hydraulic servo-valve. While the system was functional and showed no pre-impact malfunctions, investigators could not determine the exact cause of the uncommanded nosewheel deflection. The investigation also reviewed the crew's actions, the runway conditions, and the aircraft's maintenance history.
Investigators found that the runway was wet but hard-packed, and a 15-knot crosswind was not significant enough to cause the deviation. Maintenance records showed that while a service bulletin (SB226-32-058) suggested the optional replacement of the hydraulic servo-valve, the operator's records had been affected by a manufacturer printing error, and the component had not been replaced. Furthermore, the investigation looked into the crew's communication and the clarity of the aircraft's emergency procedures for ground directional control loss.
Findings
- The aircraft left the runway because the nosewheel was probably deflected to the left for undetermined reasons.
- A lack of communication occurred between the crew members, as the co-pilot did not inform the pilot-in-command of the difficulty in maintaining directional control.
- The crew's specific actions to maintain control were contributing factors; the pilot-in-command did not utilize the brakes or reverse thrust in a manner that might have corrected the drift.
- The crew had not received Cockpit Resource Management (CRM) training.
- There were no memorized checklist items for handling uncommanded nosewheel deflection, and the aircraft's manual procedures were difficult to implement during an active emergency.
- Replacing the hydraulic servo-valve might have prevented the occurrence.