ERA15LA240

The pilot indicated that, while landing, everything appeared normal until he felt a “jolt” during the landing rollout. The right main landing gear collapsed, and the right wing struck the runway. He stated that the airplane then veered "violently" to the right, exited the right side of the runway, and came to rest in the grass. Upon egressing from the airplane, the pilot observed that the right main landing gear had completely separated from the airplane and was in the center of the runway, about 500 ft down the runway past his touchdown point. The airplane sustained substantial damage when the right main landing gear contacted the wing spar during the gear collapse. Examination of the right main landing gear assembly revealed that the assembly was fractured in four attachment locations. Flaking paint and oxidation of the metal surface indicate corrosion had occurred at the fracture locations. The main landing gear likely fractured due to corrosion fatigue at the upper inboard attachment point. Areas of fracture recontact were observed at the upper inboard fracture location, which indicate that it likely fractured before the other locations. Although this recontact could suggest a complete separation occurred before the accident flight, it is also possible that the separation occurred during the accident landing and that the recontact was the result of spring-back loads that occurred during the landing. The corrosion fatigue crack at the upper inboard attachment location initiated at the forward face of the attachment ear where it intersected the adjacent tube. The fracture surface at the upper outboard attachment had indications of fatigue cracks initiating at a similar intersection between the forward face of the ear and the tube. The fracture surfaces were substantially damaged in the fracture process, so the crack lengths before failure could not be determined; however, it is likely that fatigue cracks extended along most of the height of the ear and through the thickness of the forward plate at each upper attachment location. The sliding contact damage in the forward direction at the upper outboard attachment location combined with the bending deformation and overstress fracture at the lower attachment points also indicated that the fracture occurred at the upper attachment locations before the lower attachment locations. After separation at the upper attachment locations, the upper end displaced forward due to drag loads at the lower end, effectively rotating the assembly about the lower attachment locations, which resulted in secondary overstress fractures due to bending loads at the lower attachment points. Preexisting cracks were also observed on the lower sides of the lower attachments. However, the fracture surfaces for those areas were damaged because they were on the compression side of the fracture. The cracks did not contribute to the separation because they were on the compression side of a bending fracture. The airplane’s mostrecent annual inspection was completed 25 days before the accident. The poor condition of the landing gear should have been noticeable and detected because inspections for the landing gear should have included the lower side of the lower attachments as well as the entire upper attachment area and the areas where the ears intersected the tubes.

On June 14, 2015, about 1000 eastern daylight time, a Weatherly 201B, N1272W, was substantially damaged when it was involved in an accident near Pell City, Alabama. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 137 aerial application flight. According to the pilot, he was landing on runway 21 at St. Clair County Airport (PLR), Pell City, Alabama. The weather conditions were clear, with a slight wind favoring runway 21. The pilot indicated that while touching down for a wheel landing in the tailwheel-equipped airplane, everything appeared normal; however, as the airplane began to roll out and he was lowering the tail of the airplane to the runway, he felt and heard "a jolt." The right main landing gear collapsed, and the right wing struck the runway. He stated that the airplane then veered "violently" to the right, exited the right side of the runway, and came to rest in the grass bordering runway 21. Upon egressing from the airplane, the pilot observed that the right main landing gear had completely separated from the airplane and was in the center of the runway, about 500 ft down the runway past his touchdown point. Examination of the wreckage revealed that the airplane was substantially damaged when the right main landing gear collapsed and contacted the wing spar, which resulted in an approximate 4-inch-long jagged tear in the wing spar where the fractured landing gear tubing had impacted the forward-facing side of the wing spar. Examination of the right main landing gear assembly revealed that the assembly was fractured in four attachment locations. In many places around the attachment locations, the paint was peeling from the surface, and the underlying metal was orange, consistent with oxidation. Fatigue features were discovered at the upper inboard attachment point, and areas of fracture recontact were also observed at the upper inboard fracture location. The fatigue crack at the upper inboard attachment location appeared to have initiated from the forward face of the attachment ear where it intersected the adjacent tube, and the fatigue features extended through the thickness of the forward plate. The fracture surface at the upper outboard attachment also displayed indications of fatigue cracking initiating at a similar intersection between the forward face of the ear and the tube, with the fatigue features extending through the thickness of the forward plate. The fracture surfaces were substantially damaged in the fracture process, so the crack lengths before failure could not be determined. Sliding contact damage was also observed in the forward direction at the upper outboard attachment location. At the lower attachment points, deformation and fracture features were consistent with overstress fracture under bending loads with the lower side of the tube in compression. Additionally, evidence of preexisting cracks was observed on the lower sides of the lower attachments,although the fracture surfaces for those areas were damaged and on the compression side of the fracture. According to the pilot, the airplane’s last annual inspection of the airplane occurred about 25 days prior to the accident on May 25, 2015. Appendix D to 14 CFR Part 43, Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-Hour Inspections, indicated, in part, the following: (e) 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. (2) Shock absorbing devices - for improper oleo fluid level. (3) Linkages, trusses, and members - for undue or excessive wear fatigue, and distortion….