Aeronca O-58B accident near Bulverde, Texas, January 31, 2016

The NTSB's narrative final · quoted from the NTSB record

The commercial pilot reported that, following a normal touchdown and during the landing roll, the airplane suddenly veered to the left. The pilot corrected for the left swerve with the application of right rudder and brake. The airplane subsequently entered a right swerve. The airplane did not respond to the pilot's application of left rudder and brake inputs. The pilot reported that there was a 15-ft descending embankment and trees off the right side of the runway and that, to avoid a runway excursion, he lowered the left wing and intentionally ground looped the airplane to the right. The left wing subsequently contacted the runway surface. A postaccident examination revealed a fracture to the left main landing gear wheel casting. The wheel fracture was located along the inner bearing race shelf and resulted in the bearing being exposed. The bearing race flange had fractured circumferentially and radially in two places. Further examination of the fracture surfaces revealed areas of fatigue, which were the result of casting oxide imperfections that had been present since the wheel was cast and had developed under typical loading of the landing gear. Additionally, the observed alternating fracture features were consistent with spectrum loading, typical of those experienced by a landing gear wheel. Ultimately, the wheel failed as a result of progressive fatigue cracking. The wheel had been cast in 1942, and the owner reported that the airplane had accumulated 3,520 hours since new with 10 hours since the last inspection.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.