Slaton, TX, USA
N15400
Air Tractor AT-502
The pilot/owner of the single-engine agricultural airplane stated that the gas turbine rotation speed (Ng) was adjusted "one click" prior to departure to increase the engine power from 96 percent to 100 percent (normal range is between 50 and 102 percent). Shortly after takeoff, at an altitude of approximately 150-feet above ground level (agl), the pilot noted that the Ng speed was still at 96 percent, so he turned back toward the airport. As the pilot was turning back to the airport, the engine lost power, and he was unable to maintain altitude. The pilot made a forced landing to a dirt road, impacted a stop sign, and continued over a highway and into an open field. The pilot added that the engine was still producing enough power for him to taxi the airplane out of the field and back onto the highway. External examination of the engine revealed there was a 5-inch-wide hole in the engine's compressor housing. The engine was then disassembled into two sections; the power section module and the gas generator module. Damage of the power section included torn and nicked compressor turbine blades (leading edge), excessive FOD damage to the hot section stator vanes, the power turbine shroud was bent, buckled, and torn with several bolts sheared out of their holes. The containment ring was split in half. The power turbine stator vanes were torn and deformed. The power turbine wheel had 10 sheared blades at or near the blade root, and several other blades were broken in half. The chip detector was removed and was filled with large metal chips. The oil filter was filled with a small amount of fine metallic particles. Examination of the gas generator revealed that the compressor bleed valve, fuel manifolds, compressor turbine stator assembly, accessory gear box assembly, impeller, compressor inlet case and compressor rotor in the gas generator case, and the compressor turbine blades exhibited no anomalies. A review of maintenance records revealed that the last 100-hour inspection performed on the engine was on April 27, 2007, at a Hobbs time of 5,892.9 hours. However, there was no record of the engine's last overhaul, no record of present engine total time/time since overhaul, and no record of engine removal from the aircraft. The reason for the loss of engine power could not be determined.
On July 20, 2007, at 0930 central daylight time, a single-engine, turbine powered Air Tractor AT-502 agricultural airplane, N15400, was substantially damaged during a forced landing following a reported loss of engine power shortly after take off from the Stanton Municipal Airport (F49), near Stanton, Texas. The commercial pilot, sole occupant of the airplane, was not injured. The airplane was registered to and operated by DAC Incorporated, of Olton, Texas. No flight plan was filed for the flight that was destined for Plainview, Texas. Visual meteorological conditions prevailed for the repositioning flight conducted under 14 Code of Federal Regulations Part 91. A Federal Aviation Administration (FAA) inspector performed an on-scene examination of the airplane and interviewed the pilot. According to the inspector, prior to departure, the gas turbine rotation speed (Ng) had just been adjusted "one click" to increase the engine power from 96 percent to 100 percent (normal range is between 50 and 102 percent). The pilot reported that shortly after take off, at an altitude of approximately 150-feet above ground level (agl), the Ng speed was still at 96 percent, so he elected to turn back to the airport and land. As the pilot was turning back to the airport, the engine lost power, and the pilot was unable to maintain altitude. The pilot elected to execute a forced landing to a dirt road. During the landing roll, the airplane collided with a stop sign, crossed over a highway and into an open field. The pilot added that the engine was still producing enough power for him to taxi the airplane out of the field and back onto the highway. Examination of the airplane revealed that the leading edge of the left wing, several ribs and the wing spar sustained structural damage. The engine was examined on July 23, 2007, under the supervision of the FAA. An external examination of the engine revealed there was a 5-inch-wide hole in the engine's compressor housing. The engine was then disassembled into two sections; the power section module and the gas generator module. Damage of the power section included torn and nicked compressor turbine blades (leading edge), excessive foreign object debris (FOD) damage to the hot section stator vanes, the power turbine shroud was bent, buckled, and torn with several bolts sheared out of their holes. The containment ring was found split in half. The power turbine stator vanes were torn and deformed. The power turbine wheel had 10 sheared blades at or near the blade root, and several other blades were broken in half. The chip detector was removed and was filled with large metal chips. The oil filter was filled with a small amount of fine metallic particles. Examination of the gas generator revealed that the compressor bleed valve, fuel manifolds, compressor turbine stator assembly, accessory gear box assembly, impeller, compressor inlet case and compressor rotor in the gas generator case, and the compressor turbine blades exhibited no anomalies. A review of maintenance records revealed that the last 100-hour inspection performed on the engine was on April 27, 2007, at a Hobbs time of 5,892.9 hours. However, there was no record of the engine's last overhaul, no record of present engine total time/time since overhaul, and no record of engine removal from the airplane. Weather at the Lubbock Preston Smith International Airport (LBB), near Lubbock, Texas, located approximately 13 miles away, at 0953 reported wind variable at 3 knots, visibility 10 miles, scattered clouds at 2,100 feet, broken clouds at 8,000 feet, broken clouds at 20,000 feet, temperature 79 degrees Fahrenheit, dewpoint 64 degrees Fahrenheit, and a barometric pressure setting of 30.13 inches of Mercury.
An uncontained failure of the turbine engine's power section for undetermined reasons.
Source: NTSB Aviation Accident Database
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