Amateur-built PITTS S1 S N4714H accident near Somerville, Tennessee

Probable cause

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.

NTSB analysis

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.

Text from the NTSB. Open the NTSB docket for ERA16LA260 for the full record.