SEA04LA025

The helicopter lost engine power while the pilot was conducting long-line operations in support of a timber sale. Following the loss of engine power, the pilot performed an autorotation and competed a forced landing near the base of operations. During the landing, the helicopter sustained substantial damage to the fuselage and tail boom assembly. Post accident examination of the engine assembly revealed heavy black carbon like deposits throughout the turbine section. Additionally, extensive thermal type damage, to include metal splatter, was noted to the first and second stage turbine wheels and nozzles. A number of the turbine blade ends were melted away. Samples of the black carbon like deposits were taken from different locations throughout the turbine assembly and analyzed using Semi-quantitative X-ray Energy Dispersive Analysis. The post examination report concluded that black carbon like deposits were consistent with coked oil. There was no presence of jet fuel in the oil deposits. The origin of the oil could not be determined.

On December 8, 2003, about 1135 Pacific standard time, a Hughes 369D, N8343F, sustained substantial damage following an in-flight loss of engine power, autorotation, and forced landing near Moclips, Washington. The commercial pilot, the solo occupant, received serious injuries. The helicopter is registered to Eagle Air Helicopters, Forks, Washington, and was being operated as a visual flight rules (VFR) external load flight under the provisions of Title 14, CFR Part 133, when the accident occurred. The flight departed from a service pad near Moclips approximately 5 minutes prior to the accident.

A witness reported that the helicopter was completing its second cycle after refueling when the pilot radioed that he was experiencing a problem with the helicopter. Shortly thereafter, the helicopter impacted terrain in a level flight attitude resulting in substantial damage to the fuselage and main rotor assembly.

In a written statement the pilot-in-command reported that while conducting long-line operations, with a 100-foot long-line, the "...engine on the helicopter lost power rapidly. Altitude at this time must have been around 150 feet AGL [above ground level]. There was no sudden yaw movement or noise to indicate a compressor stall or catastrophic failure. The loss of power, although rapid, was more of a smooth decline."

The pilot further stated that after clearing the ground crew, he jettisoned the load, released the long-line, and initiated an autorotation from about 150 AGL. He stated the landing was "...hard, flat and with little forward movement" and that the landing flare was limited due to obstacles near the landing area.

On December 16, the helicopter and its engine were inspected by representatives from NTSB, FAA, Rolls-Royce and the operator at a hangar facility in Forks, Washington.

The airframe and engine and transmission were intact, however extensive impact related damage was observed to the fuselage, tail assembly and undercarriage of the helicopter. The engine assembly showed no evidence of case penetration or thermal damage.

The fuel system was intact and fuel was observed in the airframe fuel filter. A fuel system vacuum check was performed in accordance with Rolls-Royce maintenance procedures and no evidence of a pneumatic leak was noted.

Following the external examination of the airframe and engine and associated components, the engine was removed and placed on an engine stand for further examination and disassembly.

Rotation of the compressor, gas turbine and power turbine was attempted, however, the assembly would not rotate.

Examination and disassembly of the intake compressor rotor assembly revealed no evidence of damage or foreign debris. The compressor lining was intact and unremarkable. The diffuser scroll was intact and no evidence of damage or debris was noted. Both compressor discharge tubes were intact and unremarkable.

The accessory gearbox assembly was separated from the compressor and turbine assemblies. No damage or anomalies were noted to the gearbox. The accessory gears rotated manually and no discrepancies were noted.

The combustion assembly was removed from the engine assembly. The spark igniter and fuel nozzle were intact and no discrepancies were noted. The combustion outer case and combustion liner were whole, intact and no damage was noted.

During the examination of the turbine assembly, heavy black carbon like deposits were observed on the first stage turbine nozzle and heavy material erosion was noted.

Following the initial examination of the engine, the turbine assembly was shipped to Rolls-Royce for further disassembly and metallurgical examination.

On January 14, 2004, the turbine assembly was disassembled and inspected by representatives from Rolls-Royce and FAA at the manufacture's facility in Indianapolis, Indiana. The inspection revealed the following:

Heavy black carbon like deposits were noted throughout the turbine section. Extensive thermal type damage, to include metal splatter, was noted to the first and second stage turbine wheels and nozzles. A number of the turbine blade ends were melted away.

A greenish discoloration, as well as the black carbon like deposits, was observed throughout the third and fourth stages of the turbine. The turbine nozzles and turbine wheels were intact and little thermal damage was observed.

Samples of the black carbon like deposits were taken from different locations throughout the turbine assembly and analyzed using Semi-quantitative X-ray Energy Dispersive Analysis. The post examination report concluded that black carbon like deposits were consistent with coked oil. There was no presence of jet fuel in the oil deposits. The analysis was conducted by Dixie Services, Inc, Galena Park, TX.

The origin of the oil could not be determined.

On February 9, 2005, the airplane wreckage, and associated components, was released to the operator.