What happened
On a night flight from Dallas/Fort Worth, an American Airlines Boeing 737-823, registration N901AN, landed at Montreal/Pierre Elliott Trudeau International Airport during light rain. The approach was stable and the initial touchdown on Runway 2HD was normal. However, during the landing roll-out, the aircraft began to drift left of the centerline.
As the aircraft decelerated, the pilot flying attempted to correct the heading using the control wheel and rudder pedals. Despite these efforts, the aircraft continued to veer left, eventually exiting the paved surface and coming to a stop in the grass and mud approximately 90 feet from the runway edge. There were no injuries among the 106 passengers, 6 crew members, or 1 off-duty crew member on board. The aircraft sustained minor damage.
The investigation
Investigators analyzed flight data recorder (FDR) and cockpit voice recorder (CVR) data to reconstruct the event. The analysis focused on the aircraft's directional control and the crew's response to the deviation. The investigation also included Boeing-led simulations to test various failure scenarios.
Engineers examined the nosewheel steering system, including the steering metering valve, to identify any mechanical faults. While the system was found to be functional after the event, the investigation explored the possibility of a temporary steering malfunction. The investigation also looked into the lack of cockpit warnings or vibrations that might have alerted the crew to a system failure.