The purpose of the flight was for the pilot to practice touch-and-go landings in the tailwheel-equipped, tandem-seat airplane. Following nine uneventful landings, the pilot reported that he entered the traffic pattern at the destination airport. While on the base leg in the traffic pattern for landing he felt that the flight controls were “noticeably weird.” He aborted the landing attempt and tried to maneuver the airplane away from the airport. The pilot described that the airplane would not bank to the right and was descending, despite the engine power being at 2,200 rpm. The airplane continued in a left bank and the pilot was unable to level the wings, and despite application of aft elevator control input, he was unable to arrest the descent. The airplane continued toward a pasture and struck the ground left bank before striking trees. The airplane’s left wing sustained substantial damage during the impact. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. He added that when he was examining the airplane after the accident, he noted that the rear seat headset had become unstowed and had, “fallen onto / and around” the right rear rudder pedal. Based on this information, it is likely that the unsecured headset obstructed the movement of the rudder controls, resulting in the airplane’s uncommanded left bank.