NTSB Identification: FTW92LA040.
The docket is stored on NTSB microfiche number 46289.
Accident occurred Tuesday, December 10, 1991 in ARLINGTON, TX
Probable Cause Approval Date: 06/30/1993
Aircraft: BELL 206L-3+, registration: N2770X
Injuries: 2 Uninjured.

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 EXPERIMENTAL CERTIFICATED HELICOPTER WAS BEING TEST FLOWN AS PART OF THE HEIGHT VELOCITY DIAGRAM DEVELOPMENT FOR THE 206L4 CERTIFICATION PROGRAM. THE TEST PILOT WAS CONDUCTING ABORTED TAKEOFFS WHEN AT 30 FEET AND 50 KNOTS HE INITIATED AN AUTOROTATION. THE COLLECTIVE WAS LOWERED SLIGHTLY AND A HIGH DESCENT RATE OCCURRED. DURING THE DESCENT THE MAIN ROTOR RPM DECREASED AND THE HELICOPTER LANDED HARD RESULTING IN TAILBOOM BUCKLING AND SEPARATION OF THE TAIL ROTOR DRIVE SHAFT. THE PILOT'S APPLICATION OF COLLECTIVE BEFORE TOUCHDOWN DID NOT ARREST THE DESCENT RATE.

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

THE HELICOPTER'S AUTOROTATIONAL LANDING PERFORMANCE CAPABILITY WAS EXCEEDED. FACTORS WERE THE PROPER DESCENT RATE WAS NOT POSSIBLE FOR THE PIC AND SUFFICIENT INFORMATION FROM THE MANUFACTURER WAS NOT PROVIDED.

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