NTSB Identification: FTW99GA061.
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Accident occurred Sunday, December 27, 1998 in LAREDO, TX
Probable Cause Approval Date: 03/31/2000
Aircraft: Hughes OH-6A, registration: N6638R
Injuries: 1 Minor.
: 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 public aircraft accident report.
The engine decelerated and the pilot heard the sound of the engine out audio and observed the red engine out warning light illuminated. When the pilot lowered the collective to enter an autorotation, the engine and rotor RPM increased. The pilot then rolled the throttle off to regain control of the engine RPM. During touchdown, the helicopter landed hard, and the main rotor blades contacted the tailboom. A test run of the engine in a test cell revealed that the engine RPM was not controllable above flight idle, and the engine had a tendency to overspeed and overtemp when the power was advanced. The engine power turbine governor was removed and replaced with an operational unit. The engine operated within normal operational parameters after the governor was replaced. Examination concluded that the failure of the governor's drive shaft bearings resulted in excessive radial and axial play of the drive shaft, which led to a reduced fuel flow to the engine.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The loss of engine power as result of the failure of the power turbine governor. A factor was the lack of suitable terrain available to the pilot for the forced landing. Full narrative available
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