NTSB Identification: FTW91FA070.
The docket is stored on NTSB microfiche number 44671.
Nonscheduled 14 CFR
Accident occurred Tuesday, April 23, 1991 in SO. MARSH 275
Probable Cause Approval Date: 01/25/1993
Aircraft: BELL 206B, registration: N213AL
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 PILOT DID NOT MAKE THE REQUIRED 15 MINUTE RADIO CHECK AFTER DEPARTURE FROM AN OFFSHORE RIG AND A RADIO AND AIR SEARCH WAS INITIATED. ABOUT TWO HOURS LATER, DEBRIS WAS FOUND FLOATING ABOUT THREE MILES FROM THE DEPARTURE POINT. RECOVERED DEBRIS INDICATED THAT THE AIRCRAFT HAD EXPERIENCED AN INFLIGHT SEPARATION OF THE VERTICAL FIN AND SUBSEQUENT MAST BUMPING. METALLURGICAL EXAMINATION OF THE VERTICAL FIN ATTACHMENT FITTINGS REVEALED THAT THEY HAD SEPARATED DUE TO FATIGUE INDUCED BY CORROSION AND CORROSION PITTING. THE EXAMINATION ALSO REVEALED THAT THE OPERATOR HAD UNSUCCESSFULLY ATTEMPTED TO COMBAT THE CORROSION DURING A REFURBISHMENT OF THE AIRFRAME. ALL OF THE FATIGUE FRACTURES APPEARED OLD AND ONE HAD PAINT IN THE FRACTURE.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE INFLIGHT STRUCTURAL FAILURE AND SEPARATION OF THE VERTICAL FIN WHICH LED TO A LOSS OF CONTROL AND MAST BUMPING. THE FAILURE OF THE FIN WAS DUE TO INADEQUATE CORROSION CONTROL EFFORTS BY THE OPERATOR.
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