ATL00LA063
ATL00LA063

On June 10, 2000, about 1425 eastern daylight time, a Hughes 369A helicopter, N330CM, registered to Corporate Troubleshooters Inc., was substantially damaged when it collided with the ground following a loss of engine power during final approach to landing at Clayton County/Tara Field Airport in Hampton, Georgia. The private pilot received minor injuries, and the two passengers were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight being conducted under Title 14 CFR Part 91. The flight originated from Hampton, Georgia, at 1410.

According to the pilot, at 1130 on the day of the accident, he flew the helicopter in the local traffic pattern. He stated that he had been having previous difficulties with the turbine outlet temperature (TOT) and engine starting following the recent replacement of the fuel control unit (FCU). Prior to departure, he reported having difficulty starting the engine, and was able to start it on the second attempt. During the flight, all engines gauges were indicating normal.

At 1410, the pilot again departed with two passengers on board and 120 pounds of Jet A fuel for a local demonstration flight. Again, he was able to start the engine on the second attempt. After flying in the local area for approximately 10 minutes, the passenger in the left seat observed the engine oil temperature gauge and noted that it was indicting just under "red-line." The TOT was in the yellow range and the fuel flow was higher than normal. Two to three minutes later, the pilot elected to return to the airport to land. While approximately 100 to 120 feet above ground level at 40 knots, the engine lost power. The pilot entered autorotation, but said he was "too low and too slow to be successful." The helicopter collided with the ground between the runway and the parallel taxiway, and rolled over on the right side.

Examination of the helicopter at the accident site revealed that the tail boom assembly had been severed.

On June 20, 2000, the helicopter was examined in a hangar located at the airport. In attendance were investigators with the Safety Board, Federal Aviation Administration (FAA), McDonnell Douglas Helicopters and Rolls-Royce engines. A continuity check of the engine controls was performed. Drive train continuity from the engine to the main rotor was examined and no discrepancies were observed. Fuel was present in the main fuel tank. A vacuum test was performed on the fuel system and no leaks were detected. The engine's upper and lower chip detectors were removed and inspected, and carbon and small particles were present. Examination of the engine revealed that a local fire occurred below the outer combustion cover that burned a one-inch hole through the aluminum skin on the right side engine door. The turbine assembly was discolored, and both the turbine and compressor assemblies were seized.

The engine was shipped to the facilities of Rolls Royce in Indianapolis, Indiana, and a disassembly inspection was performed on July 12, 2000. During the teardown, two pieces of metal were found; one in the outer combustion cover (OCC), and another in the outer rim of the first stage nozzle on the pressure side. A post-metallurgical analysis was performed and the material was determined to be a copper-aluminum alloy, a material that is not used in the manufacture of the engine or any of its components. The first stage turbine wheel was damaged and approximately fifty percent of the blade tips were fractured and missing. The failure was determined to be due to tensile overload. Copper aluminum material was found on the first stage turbine wheel blades fracture surfaces and on the first stage turbine blade track of the second stage nozzle. The engine examination also revealed that the compressor was not damaged.

A review of the engine logbooks revealed that the engine was last overhauled on May 22, 1992, at an engine total time of 2,306.0 hours. The most recent major maintenance inspection was performed on February 21, 2000, at an engine total time of 3,067.4 hours. At that time, the FCU was replaced. The engine had accrued 30.1 hours since the last inspection was performed. According to the owner/pilot, he purchased the helicopter in December of 1999, and was unaware of the latest maintenance inspection performed on the engine that would have necessitated the removal of the outer combustor.

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