SOUR LAKE, TX, USA
N4002G
Bell 47G-3B-1
The helicopter lost engine power during takeoff due to contaminated fuel. The commercial helicopter pilot stated that the night before the accident flight, the fueling truck, which contained three tanks (one each for water, chemicals, and fuel), was checked. The pilot stated that the fuel appeared 'normal' that night. The following day, prior to the accident flight, the helicopter was 'refueled without sumping the tanks.' The pilot added that during takeoff, the engine lost power about 50 feet above the ground, at 30 miles per hour. He executed an autorotation to the ground where the main rotor blades impacted the tail boom and the tail rotor blades contacted the ground. The pilot stated that he found 20 gallons of water in the helicopter's fuel tank after the accident. He added that he discovered the fuel truck had a crack in between the water and fuel tanks. Approximately 80 gallons of water had leaked into the truck's fuel tank. The fuel truck was 'supposed to have an aqua stop filter installed that will not pump if water is present but the wrong filter was installed.'
On July 17, 1999, at 1630 central daylight time, a Bell 47G-3B-1 agricultural helicopter, N4002G, was substantially damaged during a forced landing following a loss of power during takeoff climb near Sour Lake, Texas. The commercial helicopter pilot, sole occupant, was not injured. The helicopter was owned and operated by Precision Air Services, Inc., of Selma, Alabama. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The helicopter was departing for a local flight at the time of the accident. During a telephone interview conducted by the NTSB investigator-in-charge, the pilot reported that the night before the accident flight, he checked the fueling truck, which contained three tanks: one each for water, chemicals, and fuel. The pilot stated that the fuel appeared "normal" that night. The following day, prior to the accident flight, the helicopter was "refueled without sumping the tanks." The pilot stated that during takeoff, the engine lost power about 50 feet above the ground, at 30 miles per hour. He executed an autorotation to the ground where the main rotor blades impacted the tail boom and the tail rotor blades contacted the ground. The pilot reported that the main rotor blades were damaged, the tail rotor blades were "destroyed", and the tail boom was severed. The pilot added that he found about "20 gallons of water in the helicopter's fuel tank" after the accident. The pilot examined the truck's tanks and found a crack between the water and fuel tanks. The pilot estimated that "80 gallons of water had leaked into the truck's fuel tank." In the enclosed Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot added that the fueling truck was supposed to have an "aqua stop filter installed that will not pump if water is present but the wrong filter was installed."
The pilot's failure to adequately preflight the helicopter's fuel system resulting in the total loss of engine power as a result of water contamination. Factors were the incorrect filter installed on the fueling truck and the pilot's improper touchdown technique.
Source: NTSB Aviation Accident Database
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