On June 14, 1993, at 1530 Pacific daylight time, a Piper PA22 20, N9618D, ground looped on takeoff at the Oakdale, California, airport. The aircraft was purchased by Edward F. Ferro on the morning of the accident. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local area personal flight. The aircraft sustained substantial damage. Neither of the occupants, who both hold private pilot certificates, were injured. The flight was originating at the time of the mishap. In his written report of the mishap, the left seat occupant stated that he did not have a medical certificate or a current biennial flight review and asked the right seat occupant to fly with him around the pattern to get the feel of the aircraft. He said that during the takeoff ground roll he glanced at the instruments and when he looked up again the aircraft was departing the left side of the runway. The pilot further reported that the left wheel encountered a large "rain wash hole" at the left pavement edge, which sheared off the landing gear and damaged the left wing. The left seat pilot said that "I realize it had been some time since I had flown a tail dragger, but I do have several hundred hours in them." According to a verbal statement from the right seat occupant, he had sold the aircraft to the left seat occupant the morning of the accident. The left seat occupant then approached the right seat occupant in the afternoon and asked the former owner to go with him for several takeoffs and landings. The right seat occupant stated that he told the new owner that the reason he sold the aircraft was that he could not fly it and was not current. The left seat occupant reportedly insisted that the former owner fly with him. During the first takeoff, the aircraft ground looped as the aircraft tail lifted off the runway, shearing off the landing gear and bending a wing. The right seat occupant stated that he purchased the aircraft in November of 1992 from the registered owner listed in the FAA aircraft registry files. The right seat occupant said he failed to file a new registration. An FAA operations inspector from the Fresno, California, Flight Standards District Office responded to the accident site and inspected the runway and runway environment. In a verbal report, the inspector stated that he observed a one-quarter inch deep depression located about four feet off the pavement edge in the area where the left seat pilot claimed to have encountered the "large rain wash hole." The inspector stated that he did not observe any large or significant defect in the surface at any point along the runway pavement or the grass area along the edge.