Somerville, TN, USA
N4714H
SORENSEN DANNY PITTS S1 S
The private pilot was conducting a cross-country, personal flight in the experimental, amateur-built, tailwheel-equipped airplane. The pilot reported that, while slowing the airplane after a normal three-point landing in a calm wind, the airplane began swerving. The airplane then departed the right side of the runway and ground looped. Examination of the wreckage revealed that the left landing gear leg had separated. Metallurgical examination of the fractured landing gear leg surface revealed a small thumbnail-like fatigue region, followed by an overstress region. A previous owner had assembled the airplane from a kit about 32 years before the accident, and it had accumulated about 875 total hours of operation. The builder did not use the stock bungie landing gear that were included with the kit. Rather, to reduce drag, he designed and constructed his own round, tapered rod landing gear. It is likely that the homemade, custom-built landing gear leg could not support the same loading as the stock bungie landing gear, which resulted in fatigue over a period of time and the gear leg's subsequent failure.
On July 14, 2016, about 1930 central daylight time, an experimental amateur-built Pitts S1-S, N4714H, was substantially damaged while landing at Fayette County Airport (FYE), Somerville, Tennessee. The private pilot was not injured. The airplane was registered to and operated by the private pilot as a personal flight conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the flight that originated from Wolf River Airport (54M), Rossville, Tennessee, about 1845.The pilot reported that after a normal three-point landing in a calm wind, the airplane began swerving as it slowed. The airplane then departed the right side of the runway and ground-looped, which resulted in substantial damage to the lower left wing. Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that the left landing gear leg had separated and exhibited corrosion. The left landing gear leg was retained and forwarded to the National Transportation Safety Board Materials Laboratory for further examination. Metallurgical examination of the fracture surface revealed a small thumbnail like fatigue region followed by an overstress region. The single-seat, bi-wing, tailwheel-equipped airplane, serial number DS-1, was assembled from a kit in 1984 and issued an FAA experimental airworthiness certificate. Its most recent condition inspection was completed on April 23, 2016. At that time, the airframe had accumulated 865 total hours of operation. It had flown an additional 11 hours from the time of the last inspection, until the accident. The FAA inspector that examined the wreckage further stated that a previous owner built the airplane and did not use the stock bungie landing gear that was included with the kit. Rather, to reduce drag, he designed and constructed his own round tapered rod landing gear.
The failure of the left landing gear leg due to fatigue, which resulted in a ground loop during landing. Contributing to the accident was the airplane builder's installation of a custom-built landing gear rather than the landing gear included with the airplane kit.
Source: NTSB Aviation Accident Database
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