What happened
While landing on runway 35R, the crew of the aircraft experienced an unexpected left turn immediately after the first officer engaged the nose wheel steering. In an attempt to maintain the centerline, the crew applied right rudder and right brake, but the airplane subsequently exited the runway. At the time of the incident, winds were reported from the south/southwest at 12 knots with gusts up to 24 knots. An analysis of the wind conditions indicated a 13 knot tailwind, which exceeded the company limit of 10 knots. Additionally, runway skid marks suggested the aircraft was traveling at a high rate of speed late in the landing roll.
The investigation
Maintenance personnel conducted a post-incident taxi check, during which they observed that the aircraft made a left turn with a rapidly increasing rate. During subsequent repairs, maintenance crews replaced the #4 brake assembly and the nose wheel steering power lever switch. They also repaired a shorting wire located at the power lever switch. Although the nose wheel steering actuator was removed for testing, no discrepancies were found within the component itself.