NTSB Identification: FTW86FA085.
The docket is stored on NTSB microfiche number 32331.
Nonscheduled 14 CFR
Accident occurred Monday, May 12, 1986 in PINE SPRING, TX
Aircraft: BELL 206B, registration: N27785
Injuries: 2 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 HELICOPTER WAS ON A FLT TO A SITE NR GUADALUPE PASS, AN AREA KNOWN FOR ERRATIC & GUSTY WNDS. AS THE PLT WAS ON AN APCH TO A HI MEADOW (ELEV APRX 5460'), THE HELICOPTER ENTERED A DSCNT & CRASHED WELL SHORT OF THE INTENDED LNDG AREA. A WITNESS RPRTD THE MAIN ROTOR RPM SLOWED & THE ROTOR BLADES CONED PRIOR TO IMPACT. THERE WAS EVIDENCE THE HELICOPTER IMPACTED IN A LVL ATTITUDE & AT A HIGH RATE OF DSCNT. AN INV REVEALED THAT A COUPLING ON THE ENG-TO-MAIN TRANSMISSION DRIVE SHAFT HAD BECOME DISCONNECTED. THERE WAS EVIDENCE THAT THE MALE DRIVESHAFT COUPLING WAS NOT PROPERLY SECURED TO THE FLANGE ON THE MAIN ROTOR DRIVESHAFT'S ENG END. EIGHT DAYS PRIOR TO THE ACDNT, AN AIR COND SYS WAS INSTALLED ON THE HELICOPTER. THIS WOULD HAVE REQD THAT A DRIVE SHAFT COUPLING BE DISCONNECTED. THERE WAS EVIDENCE THAT THE SELF LOCKING NUTS WERE REUSED WHEN THE COUPLING WAS RECONNECTED.
The National Transportation Safety Board determines the probable cause(s) of this accident to be:ROTOR DRIVE SYSTEM,ENGINE TO TRANSMISSION DRIVE..DISCONNECTED
The National Transportation Safety Board determines the probable cause(s) of this accident to be:MAINTENANCE,INSTALLATION..IMPROPER..OTHER MAINTENANCE PERSONNEL
The National Transportation Safety Board determines the probable cause(s) of this accident to be:IMPROPER USE OF PROCEDURE..OTHER MAINTENANCE PERSONNEL
WEATHER CONDITION..HIGH DENSITY ALTITUDE
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