On June 30, 1996, about 1045 eastern daylight time, a homebuilt Glasair 2SFT, N16CD, registered to a private individual, was substantially damaged on landing at the St. George Island Airport, Apalachicola, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The private-rated pilot and pilot-rated passenger were not injured. The flight originated about 0915 from the Cartersville Airport, Cartersville, Georgia. The pilot stated that she entered the traffic pattern to land on runway 14 with a crosswind from the left about 10 knots. While on short final approach with partial flaps extended and an indicated airspeed of 90 miles per hour, the flight encountered a downdraft. She added partial power and the airplane landed short of the runway on grass then rolled onto the runway separating the nose landing gear. She further stated that the engine responded when she added power and she only applied a slight pitch up correction when adding power. Examination of the airplane revealed that the four each AN3-14A bolts that secure the nose gear trunnion attach plate to the nose gear support rib were bent and the threads were stripped. According to a representative of the designer of the prototype airplane, a Glasair 1 FT, the original engine installed was a Lycoming O-320E2D model with a wood fixed pitch propeller. Additionally, the original design only indicated that four each AN3-14A bolts to be installed to secure the nose gear trunnion attach plate. The builder of the airplane installed a model IO-360-A3B6 engine with a constant speed propeller and he stated he followed the plans pertaining to the nose gear trunnion attach plate installation. The installed engine/propeller combination weighed about 100 pounds greater than the prototype installed engine/propeller combination.