On May 28, 2006, approximately 1015 central daylight time, a single-engine Robinson R44 helicopter, N42KJ, was substantially damaged following a reported loss of power and collision with the water at the Cedar Creek Lake near Payne Springs, Texas. The commercial pilot and one passenger sustained serious injuries and one passenger received minor injuries. The helicopter was registered to KJ Helicopter Services, Inc., of Irving, Texas, and was being operated by a private individual. The helicopter departed from the Garland/DFW Heloplex (T57), near Garland, Texas, about 0949. Day visual meteorological conditions prevailed and no flight plan was filed for personal flight conducted under 14 Code of Federal Regulations Part 91. Prior to departure, the 1,350-hour private helicopter pilot conducted an aircraft preflight; the fuel tanks were full, free of contamination, and the engine oil level was "normal". The pilot and 2 passengers then departed for a private residence located near Cedar Creek Lake; no abnormities were noted during departure or en route to the residence. The pilot reported "that within a few miles of his destination, he reduced the engine power to 21 inches and gradually descended to 900 feet mean sea level (msl)." The pilot added "without any indication of a problem, the engine failed." The pilot added that he lowered collective just as the low-rotor warning light illuminated and the horn sounded. The pilot added that he flared about 50 feet above the water; however, the helicopter impacted the surface of the water with "significant force." The helicopter was a Robinson model R44, Raven I, and was powered by a Lycoming carbureted reciprocating engine. The helicopter was equipped with an "automatic" carburetor heat control for the prevention of carburetor ice at various power settings. The carburetor heat control can be overridden, or "locked-out" by the pilot. The helicopter was retrieved from the lake and transported back to T57 and placed in a secured hangar. Representatives from the Federal Aviation Administration, Lycoming engines and the NTSB Investigator-in- Charge (IIC) conducted a preliminary examination of the helicopter. The helicopter's fuselage had sustained substantial damage due to the collision with the water; additionally, the tail boom had separated from the fuselage. The tail rotor drive shaft had also separated from the transmission. The tail rotor drive shaft was separated in two, with no twisting motion at the break. The shaft was absent of rotational paint scuffs or scoring. A visual inspection of the engine failed to note any pre-impact abnormalities. An external power source was connected to the helicopter, and the "manual override" was used to disengage the engine and rotor/transmission. The engine was then turned by hand; thumb compression was obtained on all cylinders and engine continuity was established through the engine. Additionally, the carburetor heat control was found in the "automatic" position. A review of the Fixed Base Operator (FBO) fuel records revealed that on 27 May, 2006, the helicopter was filled with 38.5 gallons of 100LL aviation fuel. At 0953, the automated weather observing system at TYR, located approximately 20 miles north of the accident site, reported wind from 170 degrees at 16 knots, 10 statute miles visibility, scattered clouds at 2,500 and broken clouds at 3,400 and 4,100 feet, temperature 84 degrees Fahrenheit, dew point 70 degrees Fahrenheit, and an altimeter setting of 29.91 inches of Mercury. A review of the Carburetor Icing chart reveals that the temperature/dew point spread, puts the flight in the "Serious icing - descent power" operating realm. On 29 June, 2006, under the supervision of a representative of the NTSB, an additional examination was conducted at the Robinson Helicopter factory. Both the ignition and fuel systems were checked. The engine was removed from the airframe, placed in an engine test cell and prepared for an engine run. The engine ran at various power settings for 20 minutes. No mechanical anomalies or maintenance deficiencies were found with the engine. A reason for the reported loss of engine power could not be determined.