NTSB Identification: ANC95LA058.
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Nonscheduled 14 CFR
Accident occurred Thursday, May 25, 1995 in BETHEL, AK
Probable Cause Approval Date: 02/08/1996
Aircraft: CESSNA 206, registration: N19BR
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE COMMERCIAL PILOT DEPARTED ON AN AIR TAXI CARGO FLIGHT TO A REMOTE DESTINATION. ABOUT 20 MINUTES AFTER TAKEOFF, THE ENGINE SUDDENLY QUIT, AND THE PILOT PERFORMED AN EMERGENCY LANDING ON ROUGH TERRAIN IN A STREAM BED. AFTER RECOVERY OF THE AIRPLANE 5 MONTHS LATER, AN EXAMINATION OF THE ENGINE REVEALED THAT THE #2 MAIN BEARING HAD FAILED AND THE CRANKSHAFT HAD FRACTURED THROUGH THE CRANK CHEEK BETWEEN THE #2 ROD AND #2 MAIN BEARING JOURNALS. THE #2 MAIN BEARING WAS SEVERELY FRAGMENTED AND DEFORMED, AND THE NUMBER 2 MAIN BEARING SADDLE WAS SEVERELY DEFORMED. A METALLURGICAL EXAMINATION OF THE CRANKSHAFT INDICATED THAT IT HAD FAILED FROM FATIGUE. THE EXAMINATION ALSO DISCLOSED THAT THE CRANKSHAFT CONFORMED TO THE MANUFACTURER'S MATERIAL SPECIFICATIONS FOR HARDNESS AND NITRIDING. RECORDS SHOWED THE ENGINE HAD BEEN REBUILT BY THE MANUFACTURER ON 7/23/92 AND INSTALLED IN THE AIRPLANE ON 9/3/92. AFTER BEING REBUILT, IT HAD ACCUMULATED 1154 HOURS OF FLIGHT TIME. AT 1004 HOURS, THE OIL PUMP HAD BEEN SERVICED DUE TO LOW OIL PRESSURE. DURING A 100 HOUR INSPECTION AT 1140 HOURS, METAL WAS FOUND IN THE OIL FILTER AND THE #4 CYLINDER WAS CHANGED.

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

A FAILURE OF THE #2 MAIN ENGINE BEARING AND SUBSEQUENT FATIGUE FAILURE OF THE ENGINE CRANKSHAFT. A FACTOR RELATING TO THE ACCIDENT WAS: THE LACK OF SUITABLE TERRAIN FOR AN EMERGENCY LANDING.

Full narrative available

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