Aviation Accident Summaries

Aviation Accident Summary CHI89FA071

MILWAUKEE, WI, USA

Aircraft #1

N4247U

SIKORSKY S-58T

Analysis

THE ACCIDENT HELICOPTER DESCENDED INTO SLOPING TERRAIN AND ROLLED OVER WHILE PERFORMING EXTERNAL LOAD OPERATIONS. THE HELICOPTER HAD JUST PICKED UP A LOAD AND WAS MOVING LATERALLY WHEN IT SUSTAINED A LOSS OF ANTI-TORQUE CONTROL AND THE FUSELAGE STARTED AN UNCOMMANDED AND UNCONTROLLED ROTATION TO THE RIGHT. THE PIC WAS ABLE TO JETTISON HIS EXTERNAL LOAD INTO A CLEAR AREA AND MOVE THE HELICOPTER AWAY FROM OBSTRUCTIONS BEFORE INITIATING AN OUT OF GROUND EFFECT HOVERING AUTOROTATION.

Probable Cause and Findings

DISCONNECT OF THE TAILROTOR DRIVE SHAFT COUPLING.

 

Source: NTSB Aviation Accident Database

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