Introduction
On November 2, 2014, about 1456 Pacific standard time, a Cessna T210M, registration N1593M, was substantially damaged during a forced landing following a loss of engine power near Jacksonville, Oregon. The airplane was registered to and operated by the pilot under 14 CFR Part 91. The private pilot, sole occupant, sustained minor injuries. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the personal cross-country flight from Grants Pass, Oregon, to Long Beach, California.
Sequence of Events
The pilot reported that during cruise flight at about 12,900 feet mean sea level, the engine began to run rough with smoke developing inside the cabin, followed by oil covering the windshield. The oil pressure gauge indicated 0, though the engine continued to run; any attempt to increase power resulted in severe shaking and smoke. The pilot initiated a forced landing in a nearby field. During the landing roll, the nosewheel landing gear dug into mud, and the airplane nosed over.
Examination Findings
Local law enforcement examination revealed the right wing at the flap aileron junction was bent downward about 45 degrees. Oil was observed on the windshield and surrounding the fuselage. The wreckage was recovered for further examination.
Engine Examination
The engine was removed and sent to Continental Motors, Inc., Mobile, Alabama, for examination on March 3, 2015. A large hole was found on the top left side of the crankcase over the number 6 cylinder, and a smaller hole on the top right side over the number 5 cylinder. Visual inspection showed the number 5 and 6 connecting rods were liberated from their journals. During disassembly, the main bearing saddles for numbers 1 through 3 showed no anomalies. Numbers 4 and 5 bearing saddles had displaced material, with number 5 being worst; the oil feed hole for number 5 bearing was obstructed by displaced saddle material.
The number 1 and 2 main bearings had normal wear and score marks consistent with hard-particle passage. Number 3 main bearing had wear and scoring removing the babbit layer. Number 4 main bearing was discolored black, heavily worn, and displaced; its oil feed was unobstructed. Number 5 main bearing was similarly discolored and displaced, with its oil feed obstructed. The crankshaft remained intact but showed thermal distress at number 1, 2, and 6 connecting rod journals, and mechanical damage at number 6. Numbers 4 and 5 main bearing journals had black thermal discoloration and material displacement at number 5. All crankshaft oil tubes were clear except number 6, which was mechanically damaged.
Number 1 connecting rod showed thermal discoloration and heat distress from lack of lubrication; its oil feed was clear. Number 2 connecting rod had similar thermal distress; oil feed clear. Number 3 connecting rod showed no operational distress; bearing had some wear but no thermal distress. Number 4 connecting rod also no distress; bearing showed some wear. Number 5 connecting rod was fractured into four pieces with mechanical damage but little thermal distress; its bearing halves were found (one in sump, one outside). Number 6 connecting rod was fractured into five pieces with thermal discoloration and mechanical damage; bearing remnants in sump were thermally discolored and distorted.
Additional radiographic examination of crankshaft oil tube assemblies for number 5 and 6 connecting rods on May 4-5, 2015, in Chicago, Illinois, using computed tomography (CT) showed no low or medium density material buildup inside the oil tubes. Medium density material was noted in areas outside the tubes. The lower oil tube was deformed on one end and completely blocked by high density material similar to crankshaft material. The upper oil tube had a wall discontinuity at one end.