On August 2, 2003, about 1755 central daylight time, an Enstrom F-28C helicopter, N15SA, piloted by a commercial pilot, sustained substantial damage when the main rotor impacted the tail rotor drive shaft during a landing in a county fairground parking lot near Kankakee, Illinois. The tail rotor drive shaft separated from the helicopter and impacted the rear window of a vehicle parked in the parking lot. The aerial observation flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file. Three passengers reported minor injuries and the pilot reported that he was uninjured. The local sightseeing flight originated from the parking lot near Kankakee, Illinois, at time unknown and was returning to land at that parking lot when the accident occurred. The pilot stated: I was conducting helicopter rides at the fair ground. I made a stabilized steep approach to the landing area. Once I detected the helicopter skids come in contact with the surface I lowered the collective at that moment the helicopter dropped and lunged forward. The landing site was a nearly level area with 2-3 inch tall grass. An on-scene examination of the helicopter was performed. The helicopter was found resting in a grass area roped off for landing. The landing gear skid assemblies were not deformed. No depressions were found in the grass area around the skids. One rotor blade exhibited leading edge nicks and a red colored media transfer on its outboard section. The push-pull tube for that blade was found with its rod end separated from its assembly. The blade's drag link was found with one fork end fractured. Control continuity was established from the cockpit to the other two blades. The push-pull tube with the separation was observed to move in correct relationship to the movement of the cockpit controls. The tail rotor drive shaft was found in the parking lot adjacent to the landing area. The tail rotor drive shaft ends exhibited tears consistent with overload. The tail rotor drive shaft's color scheme was red. The rear section of the tail boom was found torn from its forward section about the splice joint aft of the stabilizer's carry through spar. Both rudder cables were intact at the tail rotor gearbox assembly and moved in correct relationship to movements of the rudder pedals. A deformed strobe light assembly was found on the ground. The examination of the helicopter detected no pre-impact anomalies. The helicopter operator supplied weight and balance data to the Federal Aviation Administration. The helicopter's center of gravity range was 92.0 to 100 inches. The operator's calculated center of gravity was 91.74 inches. At 1803, the Greater Kankakee Airport, about two miles north of the accident site, near Kankakee, Illinois, recorded weather was: Wind 170 degrees at 7 knots: visibility 10 statute miles; sky condition clear; temperature 22 degrees C; dew point 20 degrees C; altimeter 29.90 inches of mercury. Excerpts from the helicopter's flight manual stated: INTERIOR ARRANGEMENT The cabin interior is a full, three-place, side by side seating arrangement with a spacious 61" width for maximum pilot and passenger comfort.