On January 24, 2003, about 0730 eastern standard time, a Fairchild/Hiller helicopter, N543FH, operated by a private individual as a Title 14 CFR Part 91 personal flight impacted with water during a forced autorotation and landing near Fort Myers, Florida. Visual meteorological conditions prevailed. No flight plan was filed. The helicopter was substantially damaged. The commercial-rated pilot received minor injuries. The flight had originated from Page Airport, Fort Myers, Florida, a few minutes before the accident. The flight had departed the airport and was traveling in a northwest bound direction when the pilot reported to the control tower that he was going down. The pilot told investigators that the helicopter's engine had lost all power, and that he performed an autorotation into the river. The pilot was rescued from the water by another helicopter that was in the area, before the helicopter sank. An FAA-supervised examination of the wreckage was conducted at the Lee County Mosquito Control Facility. The examination was assisted by an airframe and powerplant mechanic from the Lee County Mosquito Control Facility. About a tablespoon of fuel was drained from the fuel nozzle line. Approximately 3 ounces of fuel was drained from the fuel pump filter bowl. Four ounces of fuel was drained from the main tank to the pump inline filter and 1.5 quarts of fuel was drained from the main fuel tank. Approximately 22 quarts of brackish water was drain from the main fuel tank. The mechanic stated he remembered during the examination the fuel cap was not secured and no external damage was noted to the engine. No cracks or broken parts, leakages or rods were found when the exterior surface examination of the engine was conducted. A completed NTSB Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) was not received from the pilot.