NTSB Identification: LAX01FA200.
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Nonscheduled 14 CFR
Accident occurred Sunday, June 03, 2001 in Hanapepe, HI
Probable Cause Approval Date: 12/30/2003
Aircraft: Hughes 369D, registration: N1109V
Injuries: 4 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The helicopter experienced a loss of engine power while in cruise flight. The helicopter was on its way to a rugged area to rescue a person. The pilot indicated that the engine out warning system activated, and he autorotated to a creek after determining that he was unable to manually control the engine power. The pilot performed the autorotation landing to a steep and highly vegetated area. Post-accident examination of the engine revealed its turbine section sustained hot corrosion (sulfidation) damage, which reduced the cross sectional area of the airfoils. The degree of hot corrosion damage suggests that multiple over temperature events occurred over a number of flights. The reduced cross section resulted in the liberation of one or more of the airfoils in tensile overload. The failure of the airfoils resulted in secondary over temperature and failure of other airfoils in the turbine section and eventual turbine seizure. Examination of the TOT thermocouples revealed three of the four leads were broken; however, it could not be determined as to when the fractures occurred.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: a loss of engine power while in cruise flight resulting from the failure and liberation of several turbine blades due to hot corrosion effects which weakened the blades. The hot corrosion damage was the result of multiple turbine over temperature events which occurred over several flights. Contributing factors were the lack of suitable terrain, and high vegetation. Full narrative available
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