ERA17LA298

After completing five glider tow flights, the commercial pilot landed the airplane on the turf runway. During the landing roll, the left main landing gear wheel separated from the axle; the airplane nosed over and came to rest inverted, which resulted in substantial damage to the rudder and wings. Postaccident examination revealed that the axle of the left main landing gear assembly was fractured near the end that would have been attached to the landing gear strut. There were two opposing fatigue regions on the fracture surface separated by an overstress region. The first fatigue region had a shiny appearance consistent with recontact of the fracture surfaces. The second fatigue region exhibited a more matte appearance and covered a larger area than the first region. In addition, the tread of the rubber tire exhibited a wear pattern that was not centered but instead had shifted toward the shoulder. It is possible that the axle had a crack for an unknown amount of time, then was reassembled 180° rotated when it began to fatigue again on the opposing side. As a result of the canting of the wheel because of the larger fatigue crack, the wear pattern of the tire shifted from the centerline to the shoulder of the tire. According to the maintenance records, the most recent annual inspection was performed about 12 months before the accident, which would have been the most recent time the landing gear system was completely examined. Since the origination time of the crack is unknown, the investigation could not determine if the mechanic performing the most recent annual inspection would have been able to see and identify the fatigue fracture.

On August 27, 2017, about 1530 eastern daylight time, a Cessna 305A, N1834, was substantially damaged during the landing roll at Wurtsboro- Sullivan County Airport (N82), Wurtsboro, New York. The commercial pilot sustained minor injuries. The airplane was registered to and operated by a corporation as a Title 14 Code of Federal Regulations Part 91 glider tow flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed for the local flight.According to the pilot, he completed five glider tow flights prior to the accident flight. After he landed on a turf runway, during the landing roll, the pilot noticed a "severe vibration." Next, the airplane stopped, nosed over, and came to rest inverted on the turf runway. During the accident sequence, the wings and rudder were substantially damaged. In addition, the left main landing gear wheel had separated from the axle. According to Federal Aviation Administration records, the airplane was manufactured in 1964. It was equipped with a Continental Motors Inc. O-470 series engine, a 213-hp, engine. According to the airframe maintenance logbook, the most recent annual inspection was performed on September 3, 2016, at a total time of 4,677.8 hours. At that time, it was "found to be in airworthy condition." An examination of the left main landing gear wheel axle by the National Transportation Safety Board Materials Laboratory revealed that the axle of the left main landing gear assembly was fractured near the end that would have been attached to the landing gear strut. Examination of the fracture surface using a stereo microscope revealed fracture features consistent with a fatigue fracture. There were two opposing fatigue regions on the fracture surface separated by an overstress region. The first fatigue region had a shiny appearance consistent with recontact of the fracture surfaces. The second fatigue region exhibited a more matte appearance and covered a larger area than the first region. In addition, the tread of the rubber tire exhibited a wear pattern that was not centered but instead had shifted towards the shoulder. According to Part 43 Appendix D – Scope and Detail of Items (as Applicable to Particular Aircraft) To Be Included in Annual and 100-Hour inspections, "each person performing an annual or 100-hour inspection shall inspect (where applicable) the following components of the landing gear group: 1) All units – for poor condition and insecurity of attachment. 3) Linkages, trusses, and members – for undue or excessive wear fatigue, and distortion. 7) Wheels – for cracks, defects, and condition of bearings. 8) Tires – for wear and cuts."