DFW07LA116

The reciprocating-engine powered helicopter lost engine power while in cruise flight. The 115-hour student helicopter pilot reported that the helicopter was in cruise flight at 1,500 feet when he "felt a change in torque or something." The pilot activated the carburetor heat and the engine power slowly decayed. The pilot initiated an autorotation to a marsh area. During the forced landing the main rotor blade contacted and separated the tailboom assembly. Post-examination of the airframe and engine did not reveal any pre-impact anomalies. The carburetor heat control was found in the automatic mode, the engine sparkplugs appeared normal, and there was approximately a half-tank of fuel in the helicopter's fuel cell. The reason for the reported loss of engine power could not be determined.

On May 10, 2007, approximately 1130 central daylight time, a single-engine Robinson R22 Beta helicopter, N437EM, was substantially damaged during a forced landing following a reported loss of engine power while in cruise flight near Morgan City, Louisiana. The student pilot, sole occupant of the helicopter, was not injured. The helicopter was owned and operated by Dylan Aviation LLC., of Houma, Louisiana. Visual meteorological conditions prevailed, and a flight plan was not filed for the training flight conducted under the provisions of 14 Code of Federal Regulations Part 91. The local flight departed Houma-Terrebonne Airport (HUM), near Houma, Louisiana, about 1050.

The 115-hour helicopter student pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) that the helicopter was in cruise flight at 1,500 feet when he "felt a change in torque or something." The pilot added that he proceeded to scan the engine instruments and "pulled the carburetor heat." The pilot further stated that the engine power slowly decayed and he elected to initiate an autorotation into a marsh/pipeline area.

The Federal Aviation Inspector, who responded to the accident scene, confirmed that the helicopter had sustained structural damage during the forced landing. Additionally, the aircraft's tail boom assembly was found separated from the fuselage; which was partly submerged in water and lying on its side.

Representatives of the Federal Aviation Administration conducted an examination of the helicopter and engine on May 21, 2007. Examination of the airframe and engine did not reveal any pre-impact anomalies. The carburetor heat control was found in the automatic mode, the engine sparkplugs appeared normal, and there was approximately a half-tank of fuel remaining in the helicopter's fuel tank. The reason for the loss of engine power was not found.

At 1250, the automated weather observing system at HUM, reported variable winds at 3 knots, 7 statute miles visibility, scattered clouds at 10,000 feet, temperature 84 degrees Fahrenheit, dew point 64 degrees Fahrenheit, and an altimeter setting of 29.97 inches of Mercury.

A review of the Carburetor Icing chart reveals that the temperature/dew point spread, puts the flight between the "Moderate icing - cruise power" and "Serious icing - descent power" operating realm.