On July 19, 2002, at 1610 eastern daylight time, an Eckstein RV-6A, piloted by a private pilot, was substantially damaged during landing at the Mattawan Airpark Airport (8MI3), Mattawan, Michigan. The airplane landed on runway 23 (2,000 feet x 100 feet, turf) and was rolling out under heavy braking, when it encountered a rough area of the runway surface. The nose gear subsequentially collapsed and the airplane flipped over. The flight was being conducted under 14 CFR Part 91 and was not on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot and passenger sustained minor injuries. In his written statement, the pilot noted that the approach was normal. However, during the landing flare, the airplane floated somewhat and "touched down about 500' longer than normal." He stated that the runway is rough, but firm, in the area normally used for his landing rollout. Due to the extended touchdown point, the rollout was further down the runway and the airplane encountered a "soft, sandy dip." The nose wheel dug-in to the soft area, collapsing the nose wheel strut and causing the airplane to nose over. It came to a rest inverted.