NTSB Identification: NYC94IA023.
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Incident occurred Friday, October 29, 1993 in NEW YORK, NY
Probable Cause Approval Date: 10/20/1994
Aircraft: BELL 206L, registration: N16696
Injuries: 6 Uninjured.

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

THE HELICOPTER WAS ON A LOCAL SIGHTSEEING FLIGHT AND OVER THE EAST RIVER IN NEW YORK CITY WHEN THERE WAS A LOSS OF ENGINE POWER. THE PILOT DEPLOYED THE EMERGENCY FLOATS, INITIATED AN AUTOROTATION AND LANDED ON THE RIVER. EXAMINATION OF THE ENGINE FOUND AN 'O' RING WAS IN AN IMPROPER POSITION ON THE TURBINE SPLINED ADAPTER WHICH CONNECTS THE TURBINE AND COMPRESSOR SECTIONS OF THE ENGINE. IN ADDITION, THE SPLINED END WAS DRY OF LUBRICATION AND WORN TO THE POINT OF DISENGAGEMENT BETWEEN THE COMPRESSOR AND TURBINE. ACCORDING TO THE FAA, DURING ENGINE ASSEMBLY, THE 'O' RING IS INSTALLED AND CHECKED TO SEE THAT IT IS IN THE PROPER POSITION, THEN THE ENGINE HALVES ARE ASSEMBLED. DURING THE ASSEMBLY, WHEN THE 'O' RING IS NO LONGER VISIBLE IT COULD BE ROLLED OUT OF POSITION OR DAMAGED. THIS COULD PREVENT LUBRICATION FROM REACHING THE SPLINED END.

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

Inadequate maintenance which resulted in the improper alignment of the 'O' ring on the spur adapter gear drive which caused lack of lubrication and wear of the gear drive and the disengagement of the compressor and turbine.

Full narrative available

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