What happened
A flight instructor was conducting tailwheel transition flight instruction for a private pilot. Prior to the accident, the crew had successfully completed eight stop-and-go landings. During the landing on runway 19, the student pilot applied the brakes during the landing roll. This application caused the Cessna (type not specified in source) to ground loop to the right. During the maneuver, the left wing struck the ground, resulting in substantial damage to the left wing. Both occupants were not injured.
The investigation
Following the accident, the student pilot reported that the left brake pedal felt "mushy" and was less effective than the right brake during application. An FAA airworthiness inspector examined the aircraft at the airport and identified signs of brake fluid leaking from the left brake assembly. Upon disassembling the left brake assembly, the inspector discovered that the seals were severely weathered and worn.