On August 12, 1993, at 1230 central daylight time, a Bell 47-G5 helicopter, N1347X, operated by Clarke Environmental Mosquito Control, Inc., Roselle, Illinois, sustained substantial damage from a hard autorotative landing near Schaumburg, Illinois. The commercial pilot received minor injuries. The aerial application flight originated at the Schaumburg Air Park at 1225. No flight plan was filed, and visual meteorological conditions prevailed at the time. The helicopter was serviced at the Schaumburg Air Park before takeoff. The load was 50 gallons of spray mixture, and 55 gallons of fuel. Witnesses at the airport said the helicopter used the entire runway to become airborne. The pilot reported he leveled off at 500 feet above ground level. After levelling off he heard a loud bang behind him, and the helicopter began to vibrate. The pilot said he entered an autorotation and picked out a landing site to his right. He flared the helicopter at 50 feet, and stated he felt no response when he raised the collective. The helicopter landed hard. The helicopter was examined by an FAA Airworthiness Inspector. The inspector reported the flight control system was functional. The engine was examined, and a functional test run was performed. The inspector noted no problems with the engine.