NTSB Factual Report

On May 28, 2005, at 1620 mountain daylight time, a McDonnell Douglas DC-9-82, N911TW, operating as American Airlines (AA) Flight 1125, departed the right side of runway 35R on landing at the Denver International Airport (DEN), Denver, Colorado. The airplane sustained minor damage when it struck a runway edge light during the landing roll. Visual meteorological conditions (VMC) prevailed at the time of the incident. The scheduled domestic passenger flight was being conducted on an instrument flight rules flight plan under the provisions of Title 14 Code of Federal Regulations Part 121. The captain, first officer, 3 flight attendants, and 109 passengers on board were not injured. The flight originated at the Dallas-Fort Worth International Airport, Fort Worth, Texas, at 1541 central daylight time, and was en route to DEN.

According to the captain and first officer statements, they were cleared by air traffic control for the visual approach to runway 35R (12,000 feet in length by 150 feet in width). On final approach at 700-800 feet agl, an aural wind shear alert warning was sounded with no secondary system indications. The remainder of the approach was uneventful, and the approach was stabilized at 500 feet agl in VMC. The airplane touched down on runway centerline at the 10,000 foot runway marker. Shortly after the nose wheel touched down, the airplane drifted to the right. The crew attempted to correct the right drift by applying full left rudder, left aileron, and differential braking; however, the inputs were "no help." Prior to the airplane departing the runway surface, the crew applied both brakes to minimize the speed during the excursion. The flight crew maneuvered the airplane back onto the runway, and subsequently, the airplane came to rest on the left side of the runway.

An examination of the runway by a Federal Aviation Administration inspector revealed skid marks from the left and right main and nose landing gear tires. The skid marks began near the center of the runway and continued to the right until the departure from the paved surface. The right main landing gear skid marks crossed over the base of the damaged runway edge light. Examination of the airplane revealed the #4 brake line (right main landing gear) was severed. On May 30th, the airplane was ferried to AA maintenance facility, Tulsa, Oklahoma, for further examination.

According to AA maintenance records, a "Heavy 4 C-check" was completed in Tulsa on April 28, 2005. During the check, the nose landing gear (NLG) assembly was replaced. On the second functional check flight (FCF), the following discrepancy was reported, "...During alternate gear check with [alternate] gear handle extended, landing gear handle up, [engine hydraulic] pump high, aux pump and transfer pump off [nose wheel steering] tiller has no 4 [degree] restriction." Maintenance corrective action to that entry reported, "Re-rigged ground sense cable per MM 32-23-01-21 and rigged nose wheel steering push rods in cam slots per 32-51-01. [Operations] and rigged checked good..."

A review of the aircraft maintenance logbook revealed that on May 1, 2005, a flight crew reported, "During landing roll, aircraft drifted to the right of runway. Full left rudder and left [differential] braking would not correct drift. Tiller used to correct drift." Maintenance corrective action to that entry reported, "Made adjustment and test of nose gear steering as per MM (Maintenance Manual) 32-50-00-2, functional check normal on taxi." On May 12, 2005, another flight crew reported, "Nose wheels are turned [approximately] 10 [degrees] right with steering tiller centered." Maintenance corrective action to that entry reported, "Checked rig per MM, taxi checked a-ok. Cleared log item #65."

A review of the aircraft maintenance logbook discrepancies for the previous 6 months revealed no other entries for Air Transport Association (ATA) Codes 27 (Flight Controls) and 32 (Landing Gear).

The digital flight data recorder (DFDR) data was downloaded by the NTSB Vehicle Recorders Laboratory in Washington DC. A review of the data was consistent with the pilots' account of the landing sequence.

According to American Airlines engineering, Boeing and American Airlines personnel examined the airplane in Tulsa, Oklahoma. Per an engineering bill-of-work and Boeing recommendations, the NLG assembly was removed and replaced, and several components and systems were functionally checked per applicable workcards and maintenance manuals. No anomalies were noted during the checks that were contributory to the incident.

On June 6, 2005, taxi checks were accomplished by AA maintenance personnel, and no braking or steering discrepancies were noted. On June 7, 2005, a FCF was accomplished. The purpose of the FCF was to specifically check the function of the braking and steering systems under a variety of operating conditions. During the FCF, no braking or steering discrepancies were noted. Two additional FCF were accomplished with at least 13 landings. With no anomalies noted during the functional checks, the airplane was returned to service on June 11, 2005. For 30 days, AA operations engineering downloaded and analyzed the DFDR at every major maintenance base stop (every day or 2 days) to monitor any anomalies. No subsequent anomalies or discrepancies were noted.

The reason for the occurrence was not determined.

NTSB Probable Cause

the reason for the occurrence was not determined.