LaGrange, GA, USA
N134BH
Beech A45
The pilot stated that, while in cruise flight at 7,500 feet, the engine vibrated severely, and the propeller separated. The airplane collided with trees during emergency landing, and the propeller was not located. Examination of the engine revealed the crankshaft was fractured forward of the alternator drive gear. Examination of the fracture surface at the crankshaft separation revealed features consistent with fatigue fracture under torsional loading. Blue tinting was visible near the middle of the No. 4 main journal. Several ladder cracks were observed on the No. 4 main journal surface adjacent to the blue-tinted region. A large crack in the No. 4 main journal surface continued forward through the alternator drive gear and to the exposed fatigue fracture at the crankshaft separation. Scanning Electron Microscope examination of the crack revealed crack arrest lines and marks emanated from an area at the journal surface; the fracture surface within the origin area displayed an appearance consistent with an overstress fracture. Hardness testing of the material revealed no evidence of anomaly. According to the maintenance logs, the Continental IO-520-B2 engine received a field major overhaul on October 10, 1974. The engine received a top overhaul on July 1, 2002, at an hour meter reading of 1000.0. The hour meter reading on the airplane at the accident site was 1053.7. According to Teledyne Continental Service Information Letter SIL98-9A, the recommended time between overhaul (TBO) periods for the IO-520-B series engine is 1700 operating hours or 12 years, whichever occurs first.
On July 16, 2004, at 1033 eastern daylight time, a Beech A45, N134BH, registered to private owners and operated by the commercial pilot, collided with trees during an emergency landing following a loss of engine power near LaGrange, Georgia. The personal flight was operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed. The commercial pilot reported no injuries, the private pilot-rated passenger received minor injuries, and the airplane sustained substantial damage. The flight departed Warren County Memorial Airport, McMinnville, Tennessee, about 0820 central daylight time on July 16, 2004. The pilot stated that, while in cruise flight at 7,500 feet approximately 20 miles north of LaGrange, Georgia, the engine began to vibrate severely. The pilot obtained nearest airport information from air traffic controllers and his global positioning system (GPS). As the flight continued toward the LaGrange-Callaway Airport, LaGrange, Georgia, the vibration continued and the pilot could not maintain altitude. The pilot searched for a landing area and saw only a lake and areas of pine trees, and engine oil was visible on the right side of the canopy. The pilot stated that, as he aligned the airplane for an emergency landing, the engine vibration stopped, and engine oil covered the canopy completely and obstructed his view. The pilot stated that at this point the engine was running smoothly, but the propeller was no longer attached, and he shut down the engine. The pilot executed a landing into an area of small pine trees, exited the airplane with the passenger, and called the local 911 operator from his cell phone. Examination of the airplane revealed damage to the wings, fuselage, and empennage. During the post-accident examination of the airplane, the engine was disassembled for further examination. A crack was observed on top of the left crankcase half at the fourth bolt hole from the rear; the crack extended downward and forward above the No. 2 cylinder. Both crankcase halves were damaged at the forward end, and the Nos. 4 and 5 main bearing supports were damaged with fretting on the surfaces. The Nos. 4 and 5 main bearings were damaged. The oil transfer collar was broken, with one piece attached to the left crankcase half and other pieces found in the oil sump. The crankshaft was fractured forward of the alternator drive gear, and the forward section including the No. 5 main journal was not located. The crankshaft counterweights were intact with the plates and snap rings in place. The crankshaft was shipped to the National Transportation Safety Board, Office of Research and Engineering, Materials Laboratory Division, Washington, D.C., for examination. Examination of the fracture surface at the crankshaft separation revealed features consistent with fatigue fracture under torsional loading. Crack arrest lines were visible consistent with fatigue crack propagation from aft to forward. Blue tinting was visible near the middle of the No. 4 main journal, and the journal appeared shinier than the others. Several ladder cracks were observed on the No. 4 main journal surface adjacent to the blue-tinted region. A large crack in the No. 4 main journal surface was oriented at an approximate 45-degree angle to the longitudinal axis of the crankshaft, and it continued forward through the alternator drive gear and to the exposed fatigue fracture at the crankshaft separation. The large crack intersected the No. 4 main journal oil passage hole. A secondary crack in the No. 4 main journal surface was oriented approximately parallel to the longitudinal axis of the crankshaft. The large crack in the No. 4 main journal surface was opened and examined under a Scanning Electron Microscope. Crack arrest lines and marks were observed emanating from an area at the journal surface; the fracture surface within the origin area displayed an appearance consistent with an overstress fracture. Hardness testing of the material revealed no evidence of anomaly. Examination of the maintenance logs revealed the airplane's Continental IO-520-B2 engine received a field major overhaul on October 10, 1974. The engine received a top overhaul on July 1, 2002, at an hour meter reading of 1000.0. The engine received an annual inspection September 3, 2003, at 1035.7 hours since major overhaul and 35.7 hours since top overhaul. The hour meter reading on the airplane at the accident site was 1053.7. According to Teledyne Continental Service Information Letter SIL98-9A, the recommended time between overhaul (TBO) periods for the IO-520-B series engine is 1700 operating hours or 12 years, whichever occurs first. The wreckage, except for the crankshaft, was released to a claims manager from LAD (Aviation) USA, Orlando, Florida, on September 10, 2004. The crankshaft was released to the same claims manager on November 17, 2004.
The maintenance personnel under-torquing of the crankcase throughbolts during top overhaul, which resulted in crankcase fretting, and the subsequent fatigue failure of the crankshaft at the No. 4 main journal. A factor was the lack of suitable terrain for forced landing.
Source: NTSB Aviation Accident Database
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