DALLAS, TX, USA
N148BH
AEROSPATIALE AS35OD
THE ENG TO TRANSMISSION SHORT SHAFT BECAME DISCONNECTED IN FLT. THIS RESULTED IN COMPLETE LOSS OF PWR TO THE MAIN ROTOR ASSEMBLY. HOWEVER, THE TAIL ROTOR ASSEMBLY WAS STILL BEING POWERED BY THE ENG. UPON COLLECTIVE PITCH APPLICATION TO STOP THE DESCENT THE ACFT YAWED ABOUT 90 DEGS TO THE RIGHT AND ALSO ROLLED ABOUT 70 DEGS TO THE RIGHT AND IMPACTED THE TRUNK OF A LARGE TREE. THIS IMPACT RESULTED IN DISINTEGRATION OF THE HELICOPTER. INVESTIGATION REVEALED THAT COTTER PINS HAD NOT BEEN INSTALLED IN THE BOLTS WHICH CONNECT THE FORWARD END OF THE SHORT SHAFT TO THE FLEXIBLE COUPLING AT THE TRANSMISSION. IT ALSO REVEALED THAT A REQUIRED 30 HR RECURRING INSPECTION HAD NOT BEEN COMPLETED AND WAS 15.9 HRS OVERDUE. THE COMPLETION OF THIS REQUIRED INSPECTION WOULD HAVE REVEALED THAT THE COTTER PINS WERE MISSING.
Source: NTSB Aviation Accident Database
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