On May 11, 1985, a Great Lakes 2T-1A-2 (registration N477M) was involved in an aviation accident near Greenville, AL. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a full-stop landing, the aircraft experienced lateral vibration and shaking, attributed by the pilot to a tailwheel shimmy. The aircraft drifted, and after differential braking, swerved off the runway and flipped over.
Summary
A pilot reported that during a full-stop, three-point landing, the aircraft began to vibrate and shake laterally while rolling on the runway. The pilot suspected the vibration was caused by a tailwheel shimmy but initially did not recognize the source. The aircraft subsequently drifted, and as the groundspeed was too slow for rudder effectiveness, the pilot applied differential braking. The aircraft then swerved off the runway and flipped over.
Examination
An examination and disassembly of the tailwheel assembly revealed no mechanical failure or malfunction. The cause of the shimmy could not be determined from the inspection.
Conclusion
No mechanical failure or malfunction was found in the tailwheel system. The exact cause of the shimmy remains unknown, but the pilot's actions to correct the drift with differential braking resulted in the aircraft departing the runway and flipping over.