The private pilot was landing the tailwheel-equipped Cessna 175 on a paved runway in Willimantic, Conn.
During the landing roll, a ground witness heard a “shimmy” when the tailwheel made contact with the paved surface. The plane departed the right side of the runway into grass, where it ground-looped.
A post-accident examination revealed that the tailwheel’s left side mounting bolts were found stripped, and the tailwheel was canted to the right; however, there were no wear signatures on the tire to indicate that it had contacted the runway in a canted position.
Based on the available information, it is most likely that the tailwheel mounting bolts were damaged during the accident as a result of side-loading forces that occurred when the pilot failed to maintain directional control during the landing.
The NTSB determined the probable cause as the pilot’s failure to maintain directional control during the landing roll, which resulted in a ground loop.
NTSB Identification: ERA13LA343
This July 2013 accident report is are provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
I have never seen tail wheel spring attach bolts strip out of the nuts. The C172 and C175 make a fairly good substitute for other tail wheel acft. mfrs. That installation is very similar to the C170 series planes too. More than likely the tire/wheel were out of balance (critical) that starting the shimmy and that the shackle bolts had been overly tightened before the incident.