NTSB Identification: FTW85FA265.
The docket is stored on NTSB microfiche number 29241.
Accident occurred Wednesday, June 26, 1985 in DALLAS, TX
Aircraft: AEROSPATIALE AS35OD, registration: N148BH
Injuries: 1 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
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.
The National Transportation Safety Board determines the probable cause(s) of this accident to be:ROTOR DRIVE SYSTEM,ENGINE TO TRANSMISSION DRIVE..FAILURE,TOTAL
The National Transportation Safety Board determines the probable cause(s) of this accident to be:MAINTENANCE,INSPECTION..INADEQUATE..COMPANY MAINTENANCE PERSONNEL
EMERGENCY PROCEDURE..NOT POSSIBLE..PILOT IN COMMAND
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