The flight instructor in the back seat of the tailwheel-equipped airplane reported that, the student pilot in the front seat had touched down on his fourth landing of the training flight. During the landing roll, the student over-controlled the rudder and the airplane veered left, and then overcorrected to the right. The instructor came onto the flight controls and applied left rudder and left brake to control the airplane back to the left. However, the airplane exited the right side of the runway and sank into the soft dirt and nosed over.

The airplane sustained substantial damage to the rudder and the left wing lift-strut.

The flight instructor reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.