On June 8, 2005, at approximately 1740 Pacific daylight time, a Micco MAC-145A, N223MJ, was substantially damaged during landing which followed a hard landing at Aurora State Airport, Aurora, Oregon. The commercial pilot and his pilot certificated passenger were not injured. Sportsman Airpark, Inc., was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal, demonstration flight that originated from Aurora State Airport, approximately one hour before the accident. No flight plan had been filed. The pilot said that he was taking a pilot certificated passenger for a sales-demonstration ride. He said that the passenger flew most of the flight to get used to the flight characteristics of the airplane. According to the pilot, on their final landing the passenger got the airplane into a high rate of descent on final. He (the pilot) took control of the airplane, added power for a go-around, but impacted the runway hard, bouncing back into the air. He continued the go-around. The pilot said that he noticed the upper wing skin at a splice had popped some rivets and was sticking up a few inches near the leading edge. About the same time, a witness on the ground radioed them saying that their left main landing gear appeared to be damaged. The pilot said that he held over the airport until emergency equipment could get in place. During the landing sequence, the airplane veered off the left side of the runway, and subsequently folded the right main landing gear under the airplane. Postaccident examination of the airplane revealed that the left aileron, upper left wing and both main wheel wells were bent or wrinkled.