On September 28, 2001, about 1345 Alaska daylight time, a tailwheel-equipped Slepcev Storch SS-MK4 experimental/homebuilt airplane, N69UP, sustained substantial damage during a landing at Merrill Field, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight when the accident occurred. The private certificated pilot/owner, and a pilot rated passenger, were not injured. Visual meteorological conditions prevailed. The flight originated at Merrill Field, about 1300. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) at the accident scene on September 28, the pilot/owner reported that he was seated in the rear of the airplane which is a 3/4 scale production of a German airplane. He said he was allowing the passenger, seated in the front seat, to fly the airplane as the prospective buyer of a similar airplane. At the time of the interview, the passenger had left the accident scene. The pilot/owner said that during the landing roll on runway 24, the airplane began to skid to the right and departed the right edge of the paved runway. The left main landing gear assembly separated from the fuselage, and the left wing struck the ground. The wing had wrinkling of the upper metal surface at the outboard end. A Federal Aviation Administration (FAA) Aviation Safety Inspector, Anchorage Flight Standards District Office (FSDO), reported that he inspected the left wing on October 23, 2001, after if was opened by a mechanic. The wing had damage to the rear spar and wing ribs. Since the pilot/owner reported that he was not flying the airplane, an NTSB Pilot/Operator report (NTSB form 6120.1/2) was sent by mail to the passenger. The passenger returned the form, stating that he was seated in the rear seat, and was not flying the airplane at the time of the accident. On October 29, 2001, the FAA inspector informed the NTSB IIC that he interviewed the pilot/owner by telephone. During that conversation, the pilot/owner told the inspector that he was flying the airplane. The inspector also obtained a copy of a letter sent by the pilot/owner to the FAA's Reno FSDO, concerning the airplane's operating limitations. In the letter to the Reno FSDO, the pilot/owner indicated he ground looped the airplane in Anchorage. An NTSB Pilot/Operator report form was sent to the pilot/owner on October 29. He did not return the report.