NTSB Identification: MIA02LA008.
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Accident occurred Thursday, October 11, 2001 in LakeLanier Isl., GA
Probable Cause Approval Date: 06/18/2002
Aircraft: Cessna T206H, registration: N919LL
Injuries: 2 Minor.

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

Approximately 3 1/2 hours into the flight while flying at 5,000 feet, the pilot heard a loud bang followed by "extreme vibration" of the airframe. He noted a total loss of engine power and a slight smell of smoke. The flight was vectored to a nearby airport but based on the altitude and distance, the pilot was unable to land there. The airplane was ditched with full flaps in a lake and after touchdown the airplane became inverted. The pilot and one passenger exited the airplane which was recovered revealing an oil residue in the engine compartment and also on the bottom skin of the fuselage. Examination of the engine revealed that the right side of the accessory case was displaced aft approximately 2 inches, the crankcase was fractured from the No. 5 to the No. 6 cylinder positions, the crankshaft and the No. 6 cylinder connecting rod were fracture separated. Disassembly of the engine revealed that the No. 5 main bearing saddle was separated from the crankcase and sustained "heavy damage." The parting surfaces of the crankcase halves at the No, 4 main bearing position exhibited "light fretting." Additionally, the crankshaft was fractured at the rear No. 5 crankpin to counterweight cheek area. Metallurgical examination of the fracture surface of the crankshaft revealed fatigue. No, "... non-conformances could be found with the crankshaft or other associated components." The engine had accumulated approximately 296 hours since manufacture at the time of the failure as determined by the airplane's recording tachometer. Review of the maintenance records revealed that the engine oil was drained and serviced last on September 25, 2001.

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

The fatigue failure of the crankshaft for undetermined reasons resulting in the total loss of engine power. A contributing factor in the accident was the unsuitable terrain encountered by the pilot during the forced landing.

Full narrative available

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