NTSB Identification: FTW86LA119.
The docket is stored on NTSB microfiche number 31429.
Nonscheduled 14 CFR
Accident occurred Monday, June 16, 1986 in THERIOT, LA
Aircraft: AEROSPATIALE AS35OD, registration: N229EH
Injuries: 1 Serious.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE PILOT EXPERIENCED A SUDDEN YAW IN THE HELICOPTER AT CRUISE FLIGHT. THE NG STARTED WINDING DOWN CONFIRMING AN ENGINE FAILURE. THE PILOT HAD TO EXTEND AN AUTOROTATION OVER A TREE LINE, WHICH CAUSED THE RPM TO DECREASE, AND MADE A HARD LANDING IN AN ADJACENT FIELD. DAMAGE TO THE HELICOPTER INCLUDED THE TAIL SECTION, LANDING GEAR AND MAIN ROTOR. INSPECTION OF THE ENGINE REVEALED THAT BOTH THE GEAR SPUR COMPRESOR SHAFT AND THE GEAR SPUR ACCESSORY DRIVE WERE MISSING TEETH. THE INSPECTION ALSO REVEALED THAT METAL FRAGMENTS FROM THE GEARS WERE DISTRIBUTED THROUGHOUT THE ENGINE'S LUBRICATION SYSTEM.

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

ACCESSORY DRIVE ASSY,DRIVE SHAFT..DISINTEGRATED


Contributing Factors

AUTOROTATION..PERFORMED..PILOT IN COMMAND


Contributing Factors

TERRAIN CONDITION..HIGH OBSTRUCTION(S)


Contributing Factors

ROTOR RPM..NOT MAINTAINED..PILOT IN COMMAND


Contributing Factors

PROPER GLIDEPATH..NOT POSSIBLE..PILOT IN COMMAND

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