LakeLanier Isl., GA, USA
N919LL
Cessna T206H
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.
On October 11, 2001, about 1640 eastern daylight time, a Cessna T206H, N919LL, registered to Longleaf, Llc, experienced a loss of engine power and was ditched in Lake Lanier, near Lake Lanier Islands, Georgia. Visual meteorological conditions prevailed at the time and an instrument flight rules (IFR) flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot and one passenger sustained minor injuries. The flight originated about 1300 from the Johnstown-Cambria County Airport, Johnstown, Pennsylvania. The pilot stated that approximately 3 1/2 hours into the flight while flying at 5,000 feet being vectored by FAA Air Traffic Control (ATC), he 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. He requested a vector to the nearest airport and declared a mayday. The ATC controller vectored the airplane to the nearest airport but the pilot stated that based on the aircraft's altitude and distance, he was unable to land there. He elected to ditch the airplane with the cabin doors closed; the flaps were fully extended. After touchdown the airplane went inverted; he and his passenger exited the airplane out of the copilot's door window which he partially pulled free from the attach point. The airplane reportedly sank in 85 feet of water. The ditching site was located at 34 degrees 18.40 minutes North latitude and 083 degrees 52.8 minutes West longitude. He also reported the propeller continued to windmill from the moment of the vibration until the ditching, though the vibration decreased at lower altitudes. The airplane was recovered and according to the president of the company that recovered the airplane, the oil dipstick was tight before he loosened it sometime during or after the recovery. Examination of the airplane by an FAA inspector revealed oil residue on the bottom side of the fuselage from the nose to the empennage. Visual 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. A copy of the statement prepared by the FAA inspector is an attachment to this report. Photographs taken by the FAA inspector reveal an oil residue on the right side of the fuselage from the firewall aft to the cabin door. The engine was removed from the airplane for further examination at the manufacturer's facility with Federal Aviation Administration (FAA) oversight. Examination of the engine revealed that the oil suction screen and oil filter were contaminated. 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. A copy of the engine examination report is an attachment to this report. The crankshaft was retained for metallurgical examination by the manufacturer's metallurgy laboratory. According to the metallurgical report, the fracture of the crankshaft initiated from the rear fillet radius of the No. 5 crankpin journal and propagated by fatigue through the cheek and counterweight ear. The report also states, "No non-conformances could be found with the crankshaft or other associated components." A copy of the metallurgy report is an attachment to this report. The engine had accumulated approximately 296 hours since manufacture at the time of the crankshaft 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. A copy of the engine logbook is an attachment to this report. The airplane minus the retained engine was released to Marshal Dean, of United States Aviation Underwriters, on October 19, 2001. The retained engine was also released to Marshall Dean, on April 29, 2002.
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.
Source: NTSB Aviation Accident Database
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