CEN18LA128

The airline transport pilot reported that the landing gear position lights were all green during the approach and that the landing was normal. During the landing rollout, the right landing gear collapsed. A witness stated that the landing appeared normal and was not a hard landing. The airplane skidded for about 1,200 to 1,500 ft and veered off the side of the runway, which resulted in substantial damage to the horizontal stabilizer and elevator. Examination of the airplane's landing gear parts that were broken revealed that the fracture features of the end fitting assembly mating adjustment screw, the bellcrank assembly bolt, and the flange were consistent with overstress. Examination of the fracture surfaces of the end fitting bolt revealed that it had separated through a thread root on the end of the bolt; however, the cause of the end fitting bolt separation could not be determined due to smearing and secondary damage of the fracture surface. Because the witness reported that the landing was not a hard landing, it is unlikely that the failure occurred during the accident landing sequence. It is likely that the separation of the end fitting bolt led to the landing gear collapse.

On March 22, 2018, about 1800 central daylight time, a Cessna 310 airplane, N372WP, sustained substantial damage when the right landing gear collapsed during landing roll at the Charles B. Wheeler Downtown Airport (MKC), Kansas City, Missouri. The pilot and passenger were not injured. The airplane was owned and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 on a personal flight. Visual meteorological conditions prevailed for the flight, which was on an instrument flight rules flight plan. The flight departed from the Shreveport Downtown Airport, (DTN), Shreveport, Louisiana, with MKC as the destination airport. The pilot reported that the landing gear position lights were all green during the approach and the landing was normal. During landing rollout, the right landing gear collapsed. A witness who observed the landing stated that the landing appeared normal and was not a hard landing. After the landing gear collapsed, the airplane skidded for about 1,200 to 1,500 ft and veered off the side of the runway, which resulted in substantial damage to the horizontal stabilizer and elevator. The airplane's landing gear parts that were broken during the accident were shipped to the National Transportation Safety Board's Materials Laboratory for examination. The parts that were examined included: 1) end fitting bolt with a mating spacer, 2) end fitting assembly with mating adjusting screw, 3) bellcrank assembly bolt with mating nut, and 4) part of a flange. The examination of the fracture surfaces of the end fitting assembly mating adjustment screw, the bellcrank assembly bolt, and the flange revealed that the fracture features were consistent with overstress. The failure mode of the end fitting bolt could not be determined due to smearing and secondary damage to the fracture surface. The examination of the fracture surfaces of the end fitting bolt with a mating spacer revealed that it had separated through a thread root on the end of the bolt. The bolt was bent, which prevented easy removal of the mating spacer and bushing. The fracture surface was approximately flat, but significant smearing and secondary damage obscured the finer features. Two crescent-shaped marks on the fracture surface aligned with mounded material on the sides, which was consistent with impact damage. The exact cause of the end fitting bolt separation could not be determined.