Aviation Accident Summaries

Aviation Accident Summary FTW02LA179

Crawford, TX, USA

Aircraft #1

N333UC

Schweizer 269D

Analysis

The pilot made a forced landing following a loss of engine power after takeoff. The 4,950-hour pilot reported that the aircraft was in a climb at 75 feet AGL, an airspeed of 40-50 knots, and approximately 200 feet south of the takeoff point, when the engine lost power. The pilot executed an autorotation straight ahead and landed. Examination of the engine revealed no damage in the gearbox, but significant thermal distress to several turbine components. The compressor rotated freely and the N1 and N2 sides of the accessory gearbox rotated freely. The compressor and accessory gearbox were not opened. The first stage nozzle shield appeared normal. The first stage nozzle exhibited heat distress on vanes. The first stage turbine wheel exhibited heat distress to all blades; approximately 40-50 percent of the airfoil burned away. The second stage turbine wheel exhibited heat distress to approximately 1/3 of the blades; approximately 30 percent of the airfoil burned away. The third and fourth stage turbine wheels and nozzles appeared normal. The turbine to compressor coupling exhibited rotational marks on the compressor end. The fuel control unit and power turbine governor were tested, and no anomalies were noted.

Factual Information

On June 9, 2002, approximately 1200 central daylight time, a Schweizer 269D helicopter, N333UC, was substantially damaged during a forced landing following a loss of engine power at Wales Air Field (TE92), near Crawford, Texas. The helicopter was registered to the Schweizer Aircraft Corporation of Elmira, New York, and operated by a private individual. The private pilot and passenger were not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The local flight was originating at the time of the accident. The 4,950-hour pilot, of which 525 hours were in the accident aircraft, reported that he was at the south end of Runway 17 making a takeoff to the south. The aircraft was in a climb at 75 feet AGL, an airspeed of 40-50 knots, and approximately 200 feet south of the takeoff point, when the engine lost power. The pilot executed an autorotation straight ahead and landed "hard" on a maize field that was slightly terraced and rising. The right skid collapsed and the helicopter rolled-over on its right side. The passenger and pilot exited the helicopter through the left side door entrance; there were no cabin doors installed on the aircraft. An examination of the helicopter by the FAA inspector, who responded to the accident site, revealed that the right skid and main rotor hub were destroyed. The three main rotor blades exhibited rotational damage and up-bending. The right side of the fuselage exhibited skin and structural damage. The right side engine exhaust stack was crushed against the fuselage. Burning and soot deposits emanated from the right hand exhaust area onto the right side of the fuselage. The windshield Plexiglas was broken. Under the supervision of the FAA inspector, the engine was removed from the helicopter and shipped to the manufacturer for examination. Examination of the 250C20 ngine was conducted under the supervision of the FAA at the Rolls-Royce Corporation Materials and Processes Laboratory, Indianapolis, Indiana, on August 5, 2002. The examination revealed no damage in the gearbox, but significant thermal distress to several turbine components. The compressor rotated freely and the N1 and N2 sides of the accessory gearbox rotated freely. The compressor and accessory gearbox were not opened. The first stage nozzle shield appeared normal. The first stage nozzle exhibited heat distress on vanes. The first stage turbine wheel exhibited heat distress to all blades; approximately 40-50 percent of the airfoil burned away. The second stage turbine wheel exhibited heat distress to approximately 1/3 of the blades; approximately 30 percent of the airfoil burned away. The third and fourth stage turbine wheels and nozzles appeared normal. The turbine to compressor coupling exhibited rotational marks on the compressor end. The fuel control unit and power turbine governor were tested at Honeywell Controls, South Bend, Indiana, on August 21, 2002, under the supervision of the NTSB investigator-in-charge. Testing of both units did not reveal any anomalies. Maintenance records were reviewed and no anomalies noted. According to the aircraft's maintenance records, the most recent annual inspection was completed on April 18, 2002.

Probable Cause and Findings

The loss of engine power as a result of the pilot's exceedence of the engine's temperature limits, resulting in the melting of blades on the first and second stage turbine wheels. A contributing factor was the lack of suitable terrain for the forced landing.

 

Source: NTSB Aviation Accident Database

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