On October 16, 1997, approximately 1600 mountain daylight time, N7507D, a Piper PA-22-150 converted to a tailwheel configuration, sustained substantial damage when it ground-looped during landing roll at Challis, Idaho. The private pilot and his passenger were uninjured. No flight plan was filed for the flight which had originated at Elko, Nevada about 1310. Visual meteorological conditions prevailed at the time of the accident. There was no report of the ELT actuating. The pilot stated that he had landed to the south in light and variable winds. The airplane swerved to the right; he overcorrected, and the airplane ground-looped to the right, collapsing the right main landing gear and striking the right wing, bending the rear spar. In a written statement, the pilot noted that he "realize[d] that I had landed a little hot and had not completely stalled. I had relaxed back pressure on the elevator and had not planted my tailwheel. I feel that fatigue and a lack of attention to the job at hand caused this accident." He additionally noted that "I had been working the graveyard shift for the past seven nights and I was very tired. I should have gotten a few hours of sleep before the flight."