NTSB Identification: ATL83LA160.
The docket is stored on NTSB microfiche number 20968.
Accident occurred Wednesday, April 13, 1983 in CHARLESTON, WV
Aircraft: BELL 47G-4A, registration: N4749R
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.

DURING AN APPROACH TO LAND, THE ENGINE LOST POWER AT APRX 500 FT AGL. THE PLT REPORTED THAT DURING AN AUTOROTATIVE LANDING, HE HAD TO MANEUVER TO AVOID TREES & A RIDGE IN ORDER TO LAND IN A SUITABLE AREA. DURING THIS TIME, ROTOR RPM DROPPED & A CRASH LANDING OCCURRED. A TEARDOWN OF THE ENGINE REVEALED THAT THE TIMING GEAR, PN 67687, HAD FAILED & A TOOTH HAD SEPARATED. ALSO, THE WOODRUFF KEY, PN STD-858, HAD FAILED. A METALURGICAL EXAMINATION REVEALED EVIDENCE OF FATIGUE ON BOTH PARTS. FAILURE OF THE TIMING GEAR ORIGINATED AT AN INNER CORNER OR THE GEAR KEYWAY. THE ENGINE HAD ACCUMULATED 613 HRS OF FLT TIME SINCE MAJOR OVERHAUL.

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

ENGINE ASSEMBLY,OTHER..FATIGUE


Contributing Factors

AUTOROTATION..PERFORMED..PILOT IN COMMAND


Contributing Factors

TERRAIN CONDITION..HIGH OBSTRUCTION(S)


Contributing Factors

TERRAIN CONDITION..ROUGH/UNEVEN


Contributing Factors

MANEUVER..PERFORMED..PILOT IN COMMAND


Contributing Factors

ROTOR RPM..NOT POSSIBLE..PILOT IN COMMAND

Index for Apr1983 | Index of months