What happened
The pilot was performing a landing on runway 35 under conditions involving a 6-knot right quartering tailwind. The landing initially appeared normal; however, once the aircraft reached a speed of approximately 40 to 45 knots, it began drifting to the left of the runway centerline. After the pilot attempted to correct the aircraft back to the centerline, the airplane suddenly underwent a ground loop to the right.
The pilot reported that a dirt berm, measuring approximately 3 to 4 inches in height, was located along the side of the runway. As the aircraft drifted, the left main landing gear and the tail wheel impacted this berm, causing both components to fold under the airplane.
The investigation
Observations of rubber skid marks on the runway suggested that the tail wheel was experiencing oscillation, also known as shimmying, prior to the incident.
During the recovery of the aircraft, a maintenance technician noted that the self-centering tail wheel locking device was well lubricated, in accordance with the requirements of the maintenance manual. However, the technician noted a discrepancy in practice among aerial application pilots using similar aircraft; these pilots often requested that the self-centering devices be kept dry, claiming that landing in crosswinds was easier when the mechanism was not lubricated.