Lone Pine, CA, USA
The private pilot was taking off from a dirt airstrip for a personal cross-country flight. He reported that, during the takeoff roll, it felt like the left main landing gear had hit soft soil and that the drag had increased. He attempted to correct for the condition, but the left MLG wheel continued to drag. The airplane then suddenly nosed over, which resulted in substantial damage to the wings and empennage. Postaccident examination of the airplane revealed that the left MLG wheel axle was fractured, which resulted in the separation of the left MLG wheel. A detailed examination of the fracture surface identified a fatigue fracture that emanated from the outer surface of a circumferential weld between the lateral tube portion and the vertical plate portion of the axle. The investigation could not determine what event initiated the fatigue cracking; however, the origin areas were covered in zinc-chromate primer, which indicates that the axle was painted when the circumferential weld contained a preexisting crack.
On October 24, 2015, about 1500 Pacific daylight time, a tailwheel-equipped Cessna 120 airplane, N3124N, sustained substantial damage following a nose over during takeoff at the Lone Pine Airport, Lone Pine, California. The private pilot was not injured. The flight was being operated as a personal cross country flight under the provisions of 14 Code of Federal Regulations Part 91 when the accident occurred. Visual meteorological conditions prevailed and no flight plan had been filed for the flight destined to Tehachapi, California. In a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge, the pilot stated that he was on his way back home from a weekend trip. During the takeoff roll on the dirt runway, just after raising the tail off the ground, he felt the sensation of hitting soft soil with the left main landing gear. He attempted to correct for the condition, but the left main landing gear wheel continued to drag, and then the airplane suddenly nosed over. During the nose over, the airplane sustained substantial damage to the wings and empennage. Postaccident examination of the airplane revealed that the left main landing gear wheel axle was fractured. A detailed examination of the fracture surface by the NTSB Materials Laboratory showed a fatigue fracture that emanated from the outer surface of a circumferential weld between the lateral tube portion and the vertical plate portion of the axle. The fatigue crack portions at the origin areas was covered with yellow deposits. The yellow deposits was identified by EDS spectra as zinc chromate, a compound found in primer paint.
The fracture of the left main landing gear (MLG) wheel axle due to fatigue, which resulted in the separation of the left MLG wheel during takeoff from a dirt airstrip.
Source: NTSB Aviation Accident Database
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