SOUTHWICK, MA, USA
N3109G
BELL 47G
THE PILOT WAS MAKING A RIGHT TURN DURING A HOVER-TAXI CHECK AS PART OF A POST-MAINTENANCE FLIGHT TEST. ACCORDING TO THE PILOT, THE HELICOPTER CONTINUED TO ROLL RIGHT (UNCOMMANDED), AND HE WAS UNABLE TO REGAIN CONTROL DESPITE USING LEFT CYCLIC INPUT. THE MAIN ROTORS STRUCK THE GROUND, AND THE HELICOPTER IMPACTED THE GROUND IN A NOSE DOWN, RIGHT BANK, ATTITUDE. EXAMINATION OF THE HELICOPTER INCLUDED A TEST OF THE HYDRAULIC DAMPERS WHICH WERE CONNECTED TO THE STABILIZER BAR ASSEMBLY. THE TEST REVEALED THAT THE DAMPERS WERE NOT ADJUSTED ADEQUATELY, WHICH RESULTED IN LITTLE TO NO RESPONSE TO CYCLIC CONTROL INPUT.
IMPROPER ADJUSTMENT OF THE STABILIZER CONTROL SYSTEM BY MAINTENANCE PERSONNEL.
Source: NTSB Aviation Accident Database
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