What happened
During the takeoff roll, shortly after the first officer called out the takeoff decision speed (V1) of 158 knots, the takeoff warning horn sounded. The captain initiated a rejected takeoff (RTO). To mitigate potential damage and reduce fire risk, the captain elected not to apply maximum braking, believing a more gentle application would be sufficient to stop on the runway.
During the RTO, Denver International Airport tower contacted the crew to report smoke near the left main landing gear. Shortly after, the tower reported visible fire originating from the same area. The tower alerted aircraft rescue and firefighting services to the scene. The aircraft stopped on the runway centerline with approximately 1,800 feet of runway remaining. All 7 persons aboard successfully evacuated via the L1 escape slide and were not injured.
The investigation
An inspection of the aircraft revealed significant damage to several components. Both nose landing gear tires, two main landing gear brake lines, all eight main landing gear brake assemblies, and all eight main landing gear tires sustained damage during the RTO. The maintenance manager noted that the nose and main landing gear assemblies had overheated during the event. Although the tires deflated after the aircraft came to rest, there was no indication that the tires had skidded.
Findings
Investigators determined that the takeoff warning horn was triggered by a configuration conflict between the inboard and outboard slats. An inspection of the inboard slat drive mechanism's lower left-hand anti-torque strut revealed that a rod-end bearing had migrated out of the rod-end. Additionally, two washers were missing, which allowed the anti-torque strut to ride on the bolt attaching the rod-end to the slat drive mechanism.