NTSB Identification: FTW91FA155.
The docket is stored on NTSB microfiche number 45837.
Nonscheduled 14 CFR
Accident occurred Monday, August 26, 1991 in GARDEN BANKS
Probable Cause Approval Date: 09/14/1993
Aircraft: BELL 412, registration: N3909F
Injuries: 1 Fatal,4 Serious,1 Minor,7 Uninjured.
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 FINAL APCH TO AN OIL RIG IN THE GULF OF MEXICO, WHEN TAIL ROTOR AUTHORITY & DRCTNL CTL WERE LOST. AS THE CREW BEGAN AN AUTOROTATION TO THE WATER, THE HELICOPTER SPUN OUT OF CTL TO THE RGT. IT MADE 2 TO 3 REVOLUTIONS & IMPACTED THE WATER. THE RGT FLOATATION GEAR DEPLOYED, BUT THE LEFT FLOATATION GEAR DIDN'T DEPLOY, BECAUSE THE PNEUMATIC LINES WERE PULLED APART DRG IMPACT. SUBSEQUENLTY, THE HELICOPTER ROLLED OVER DRG TOUCHDOWN IN THE WATER. THE CREW & 10 OF 11 PSGRS ESCAPED THRU THE EMERG WINDOWS. THE OTR PSGR REMAINED IN HIS SEAT (INCAPACITATED FM INJURIES) & DROWNED. AN INVESTIGATION REVEALED THE #1 HANGER BEARING HAD OVERHEATED & DISINTEGRATED AT AN EXTREMELY HIGH TEMPERATURE. SUBSEQUENTLY, THE TAIL ROTOR DRIVE SHAFT FAILED.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: OVERHEATING AND SUBSEQUENT FAILURE OF THE NUMBER ONE TAIL ROTOR HANGER BEARING FOR AN UNDETERINED REASON, AND FAILURE OF THE TAIL ROTOR DRIVE SHAFT.
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