On October 20, 1998, at 1415 mountain daylight time, a Piper PA-18-150, N335PA, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, ground-looped during the landing roll at the Billings Logan International Airport, Billings, Montana. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the private pilot and his pilot rated passenger were not injured. The flight had departed from Absarokee, Montana, about 30 minutes prior to the accident. During a telephone interview, the pilot reported that during the landing roll, the airplane began to fishtail. The pilot stated that he tried to stop the fishtail effect with rudder control, however, the condition worsened. The pilot then applied the brakes and the airplane ground-looped to the left. The right wing contacted the surface before the airplane came to rest off the side of the runway.