On March 1, 2001, about 1830 eastern standard time, a Temco GC-1B, N3301K, "registration pending", experienced collapse of both main landing gears while landing at the Sanford-Lee County Regional Airport, Sanford, North Carolina. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot, the sole occupant, was not injured. The flight originated about 1615 from the Hummel Field Airport, Saluda, Virginia. The pilot stated to an FAA inspector that she landed on the first 1,000 feet of the 6,500 foot-long runway. After touchdown, she felt that something wasn't correct with the right main landing gear and intentionally lifted off from the runway. She applied power to go around, then realized there was 4,000 feet of runway remaining. She landed again, this time approximately 1/3 to 1/2 down the runway. After touchdown, the airplane departed the left side of the runway onto grass collapsing both main landing gears. A witness reported seeing the airplane on final approach to runway 03 when the airplane was about 30 feet above ground level. The airplane was observed to land hard then bounced about the wingspan height above the ground. Engine power was heard to be applied and the airplane was observed in a steep climb. The witness did not observe the accident. A copy of the witness statement is an attachment to this report. Postaccident examination of the airplane by an FAA inspector revealed damage to the firewall. Wrinkles were noted in the left side of the fuselage aft of the firewall and also on the right side of the fuselage approximately 3 feet aft of the firewall. There was no evidence of contact with the right main landing gear or of the right wingtip with the runway. Coarse scratches were noted on the bottom of the left wing tip. According to the inspector, both main landing gears were down and locked when examined following recovery of the airplane. According to the person who purchased the airplane, the engine mount was broken. The gear box was intact and the retract mechanism was OK. A record of conversation form is an attachment to this report.