On January 10, 1999, at 1520 hours mountain standard time, a Piper PA-18A-150, N8980D, sustained substantial damage when it ground looped after landing on runway 11R at the Tucson International Airport, Tucson, Arizona. The aircraft was operated by Sun West Aviation, Inc., under the provisions of 14 CFR Part 91. The flight instructor and private pilot were not injured. Visual meteorological conditions existed for the local instructional flight and no flight plan was filed. Reported winds at the time of the accident were from 360 degrees at 4 knots. In an interview with the Safety Board, the flight instructor reported that the private pilot was receiving a conventional gear checkout and that this was the student's first flight. The flight instructor said that he briefed the private pilot on the maneuvers that they would be performing and that he should "stay off the brakes" on the landing. The instructor stated that he informed the private pilot that the brakes are a heel activated braking system. He reported that they did a preflight and no mechanical anomalies were noted. The instructor reported that before coming in to land, he reminded the student that he should not use the brakes on landing. He stated that the approach and landing were normal. On the landing rollout the aircraft made a slight move to the left and then a "violent right turn." The flight instructor reported that he put in full left rudder, but the aircraft continued to exit the right side of the runway and subsequently ground looped. The student pilot reported that no discrepancies were noted with the flight. After takeoff he practiced some maneuvers and then came back to the airport to practice touch-and-go landings. The student indicated that the pattern was normal. On the base leg of the approach, the instructor told him that they were a little high and suggested he use 50 percent flaps to correct the situation. The student reported that after crossing over the threshold, the instructor advised him to "hold it off a bit [and] NO brakes." After making a three point landing the aircraft drifted to the left of centerline. The student stated that he applied right rudder to correct for the divergence. He stated that the aircraft continued to the right and he applied full left rudder. The student pilot stated that he felt the instructor apply left rudder right after he did, but that the aircraft continued a sharp turn to the right. The aircraft subsequently exited the runway and ground looped. A Federal Aviation Administration airworthiness inspector examined the aircraft brake and control systems and no anomalies were found. Additionally, the inspector stated that he saw no evidence of brake lockup.