NTSB Identification: FTW88FA036.
The docket is stored on NTSB microfiche number 38161.
Accident occurred Monday, December 07, 1987 in GALVESTON, TX
Probable Cause Approval Date: 07/03/1989
Aircraft: BELL 412, registration: N3910U
Injuries: 2 Serious.

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 ACFT LANDED HARD IN THE GULF OF MEXICO DURING AN AUTOROTATION THAT WAS ENTERED FOLLOWING THE SEPARATION OF THE 90 DEGREE GEARBOX. THE GEARBOX (WITH TAIL ROTOR BLADES) SEPARATED DUE TO AN IMBALANCE. HOWEVER, THE GEARBOX WAS NOT RECOVERED DURING THE INVESTIGATION AND THE CAUSE OF THE IMBALANCE COULD NOT BE DETERMINED.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ROTOR DRIVE SYSTEM,TAIL ROTOR GEARBOX(90 DEG)..SEPARATION

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ROTOR DRIVE SYSTEM,TAIL ROTOR GEARBOX(90 DEG)..VIBRATION

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

ROTOR DRIVE SYSTEM,TAIL ROTOR GEARBOX(90 DEG)..UNDETERMINED


Contributing Factors

TERRAIN CONDITION..WATER

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