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On November 13, 2009, at 1651 central standard time, a Piper PA-46-310P, N667PC, experienced a total loss of engine power during descent from cruise flight. The pilot executed a forced landing on a corn field near Elk Mound, Wisconsin, which resulted in minor damage to the airplane. The pilot was uninjured. The 14 CFR Part 91 personal flight was operating on an instrument rules flight plan. The flight originated from Fargo, North Dakota, at 1530 and was en route to Eau Claire, Wisconsin.
The pilot stated that before he departed from Fargo, North Dakota, the engine oil level was 5-1/2 quarts while the engine was “hot.” While en route at a cruise altitude of 4,000 feet, the oil pressure and engine temperature indications were normal. He saw the oil pressure drop and then he heard a pop from the engine. The airplane experienced an engine problem and lost all power. The pilot performed a forced landing on a corn field.
The 1984 Piper PA46-P310, serial number 46-8508001, airplane was registered to the pilot on August 11, 2004. The airplane was originally manufactured under a type certificate with a Teledyne Continental Motors TSIO-520-BE1G engine. On September 30, 2005, the engine was removed and a Teledyne Continental Motors TSIO-550-C1B, serial number 814574-R, engine was installed on the airplane under a 2 Day’s Wings, Inc., supplemental type certificate SA00380AT. At the time of the engine installation, the airplane total time was 3,583.3 hours.
A November 22, 2006, engine logbook entry shows that at an airplane total time of 3,987.0 hours, the number 6 cylinder was removed to repair an exhaust leak. This entry states that the number 6 rod was reinstalled with new bolts and nuts after the bushing was replaced.
An April 7, 2009, engine logbook entry shows that at an airplane total time of 4,337.0 hours, the number 6 cylinder was removed due to low cylinder compression. The cylinder compressions noted on this entry were: number 1 – 67/80, number 2 – 64/80, number 3 – 66/80, number 4 – 65/80, and number 6 – 10/80. The number 6 cylinder was replaced with an overhauled cylinder, serial number PGA1610, and a new piston pin. According to the director of maintenance for the maintenance facility that performed the cylinder removal and installation, the connecting rod was not removed from the crankshaft. Also, maintenance records do not show the removal of any of the connecting rods.
Engine logbooks show that there had been 21 oil changes and 14 oil analyzes since the installation of engine serial number 814574-R. The oil change intervals ranged from 0 – 107.6 hours with the last oil change performed during the number 6 cylinder replacement at an airplane total time of 4,337.0 hours (107.6 hours before the incident). The last oil analysis was performed on April 7, 2009, and showed abnormal concentrations for: iron - 120 parts per million (ppm), copper - 20.9 ppm, aluminum – 24 ppm, and nickel – 36 ppm. The oil analysis stated, “…wear metals increased for oil time, check oil filter for chips, resample 15 to 20 hours to monitor wear trend.
The Hobbs meter at the time of the incident was 4,442.2 hours.
WRECKAGE AND IMPACT INFORMATION
Visual examination of the engine revealed holes in the engine crankcase above the number 5 and number 6 cylinder assemblies. The engine oil filter element contained metal debris. There were no oil leaks noted in the external portions of the engine other than that which had emanated from the holes in the crankcase above the number 5 and 6 cylinders.
TESTS AND RESEARCH
The engine was disassembled under the supervision of a National Transportation Safety Board (NTSB) Air Safety Investigator at Teledyne Continental Motors, Mobile, Alabama.
Piston numbers 1, 2, 3, 4, and 5 were undamaged and their piston pins were intact. The number 6 piston was fractured around its circumference about the second piston ring land and through the piston pin hole. Metallurgical examination of the fracture surface was not performed, but the surface was granular in appearance.
Connecting rod numbers 1, 2, and 3 were attached to their respective pistons. The number 4 connecting rod was fractured through at its base and cap. The number 4 connecting rod bolts and nuts were fractured through. Both of connecting rod number 4’s bolts were in place, but one of the two bolts was fractured through. Connecting rod number 5 was separated at its midpoint and at the base of the rod arm which exhibited crushing along the vertical axis. The number 5 connecting rod cap was completely separated from its rod arm. The number 6 connecting rod cap was separated from the connecting rod. The cap bolt holes were in place on the rod end of the cap.
The through bolts were removed without obtaining torque values when the engine casing was separated. The main bearing support mating surfaces were intact and did not display fretting signatures. The bearing supports did not show signs of bearing movement. The oil passages were intact and unobstructed.
Examination of the oil pump drive revealed the oil drive was intact. The oil pump cavity walls exhibited scoring about its circumference. The oil pump gear teeth were intact. The oil pressure relief valve and seat contained no obstructions.
NTSB metallurgical examination was performed on the crankshaft, piston, and connecting rod assemblies.
The number 1, 2, and 3 connecting rods and their corresponding connecting attachment bolts, nuts, and bearings were intact. The bearings showed minor wear damage and no evidence of black or blue tint.
The number 4 connecting rod contained crack arrest marks typical of a fatigue crack that emanated from one of the two arms of the connecting rod. The fatigue crack contained ratchet marks indicative of multiple origins that emanated from the exterior surface of the arm. The fatigue crack extended through the arm and terminated at the inside surface (portion corresponding to the location of the bearings). The fracture face adjacent to the inside surface contained a shear lip. The fracture features on the other fracture faces of this connecting rod were obliterated by mechanical damage.
The number 5 connecting rod fractured at the body portion and the arm portions separated from the body. The fracture faces were obliterated by mechanical damage.
The number 6 connecting rod arms were attached to the body portion of the connecting rod. The connecting rod cap was separated into two pieces. One of the two cap bolts exhibited fracture features consistent with shear. The head and shank portion of second cap bolt was attached to the cap portion. With the exception of the fracture on the first cap bolt, many portions of the fractures of the connecting rod were obliterated by mechanical damage. The deformed bearing for the connecting rod showed minor wear damage and no evidence of black or blue tint.
The connecting rod pins 1 - 5 were intact. The surface of the pins showed no evidence of a crack. The corresponding bearing for the pins showed minor wear. The pin for connecting rod number 6 was not submitted.
The crankshaft was intact and showed no evidence of a crack. The surface of rod journal number 6 was smooth, showed minor evidence of blue tint, and contained no evidence of dents. The surface of rod journal number 5 exhibited severe mechanical damage that included dents and exhibited a black tint. The surface of rod journals number 1, 2, and 3 and the main journals were smooth and contained no evidence of blue or black tint. A steel wire was inserted into and pushed with no resistance through the oil lubrication holes for the main and rod journals. No evidence of obstruction was found in the oil holes. The end of the wire that was pushed through the oil holes contained no evidence of metal fragments.