WHILE HOVERING AND SLINGING AN EXTERNAL LOAD OVER ROUGH TERRAIN THE ENG CHIP LIGHT ILLUMINATED. THE PLT IMMEDIATELY POSITIONED THE ACFT TO RELEASE THE LOAD AND THE ENG BEGAN MAKING A 'WHINING' NOISE. SEVERAL SECONDS LATER ALL ENG POWER WAS LOST. THE PLT AUTOROTATED TO A FIRM LANDING AND UPON TOUCHDOWN THE MAIN ROTOR BLADES FLEXED DOWNWARD AND SEVERED THE TAIL BOOM. EXAM OF THE ENG'S TURBINE COMPONENTS REVEALED THE PRESENCE OF A 'SLUDGE' MATERIAL IN THE SCAVENGE OIL LINE FROM THE NO. 8 BEARING AND ALSO THE PRESENCE OF A HEAVY BUILD UP OF CARBON ON THE ENGINE ROTOR 'PEASHOOTER' DRIVE SHAFT. THE ACCUMULATED MATERIAL CAUSED SHAFT RUB AND FAILURE OF THE POWER TURBINE'S INNER SHAFT. THE OPERATOR REPORTED THAT AN EARLY INSPECTION OF THE N1/N2 DRIVE SHAFT AREA COULD HAVE DETECTED THE PROBLEM AND PREVENTED THE ACCIDENT.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

Contributing Factors

LUBRICATING SYSTEM,OIL TUBING..BLOCKED(PARTIAL)

Contributing Factors

TURBINE ASSEMBLY,SHAFT BEARING..BLOCKED(PARTIAL)

Contributing Factors

TURBINE ASSEMBLY,SHAFT..FAILURE,PARTIAL

Index for Aug1985 | Index of months