Primary finding
Probable cause
The overstress separation of the left nose wheel steering linkage rod end during the takeoff roll, which resulted in a loss of control.
Investigator assessment
Analysis narrative
The student pilot reported that during the takeoff roll, about 50 miles per hour, the airplane swerved left. He stated that the nose wheel dug into the dirt runway during the swerve, and the airplane nosed over. A postaccident examination of the airplane revealed that the left nose wheel steering linkage rod end was fractured. Magnified optical examination of the linkage fracture surfaces and surrounding area revealed fracture features and deformation patterns consistent with a bending overstress separation. No indication of preexisting cracking, such as fatigue or corrosion, was noted.
Source record
Factual narrative
On September 30, 2010, about 1700 Alaska daylight time, a Cessna 150F airplane, N3569L, sustained substantial damage following a loss of control during takeoff at the Bradley Sky Ranch Airport, North Pole, Alaska. The airplane was operated as a solo visual flight rules (VFR) instructional flight under the provisions of Code of Federal Regulations (CFR) Part 91, when the accident occurred. The student pilot, the sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed for the flight that was destined for Fairbanks, Alaska. No flight plan was filed. In a written report to the National Transportation Safety Board (NTSB), the pilot reported that during the takeoff roll, about 50 mph, the airplane swerved left. He stated rudder inputs and corrective actions were not effective, and the airplane continued to veer hard left. He noted that during the swerve, the nose wheel dug into the dirt runway, and the airplane nosed over. The airplane sustained substantial damage to the left wing and vertical stabilizer. A postaccident inspection of the airplane by an FAA inspector from the Fairbanks, Alaska, Flight Standards District Office (FSDO) revealed that the left nose wheel steering linkage rod end was fractured. The linkage was sent to the NTSB’s Materials Laboratory in Washington, D.C. for examination. A Senior Safety Board Metallurgist reported that magnified optical examination of the steering linkage fracture surfaces and surrounding area revealed fracture features and deformation patterns consistent with a bending overstress separation. No indication of preexisting cracking such as fatigue or corrosion was noted.