NTSB Factual Report

On November 2, 2014, about 1456 Pacific standard time, a Cessna T210M, 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 the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot, sole occupant of the airplane, sustained minor injuries. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the personal flight. The cross-country flight originated from Grants Pass, Oregon, with an intended destination of Long Beach, California.

In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that during cruise flight at an altitude of 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 pilot stated that he observed the oil pressure gauge indicating 0, however, the engine continued to run, and that any attempt to increase the power setting 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 the mud, and the airplane subsequently nosed over.

Examination of the airplane by local law enforcement revealed that the right wing at the flap aileron junction was bent downward about 45 degrees. Oil was observed on the windshield and surrounding the fuselage area. The wreckage was recovered to a secure location for further examination.

The engine was removed from the airframe and sent to the facilities of Continental Motors, Inc., Mobile, Alabama, for further examination. The engine was examined on March 3, 2015, by representatives from Continental Motors under the supervision of the NTSB IIC. The examination revealed a large hole on the top left side of the crankcase over the number 6 cylinder, and a smaller hole on the top right side of the crankcase over the number 5 cylinder. Visual inspection through each hole revealed that the number 5 and number 6 connecting rods were liberated from the connecting rod journals. The engine was subsequently disassembled and inspected.

The crankcase halves remained secured to each other. The main bearing saddles for the number 1 through number 3 bearings did not display any anomalies. The number 4 and number 5 bearing saddles displayed displaced material with the number 5 being the worst. In addition, the oil feed hole for the number 5 bearing was obstructed by displaced saddle material. The oil galleys on the cylinder 2, 4, and 6 side of the crankcase were free of debris, with the exception the hole at the number 5 main bearing.

The number 1 and 2 main bearings displayed normal wear and a few score marks consistent with hard-particle-passage. There was no sign of lock tab movement or lock slot elongation. The number 3 main bearing displayed wear and scoring that removed the babbit layer and displayed the copper underlay. There was no sign of lock tab movement or lock slot elongation. The number 4 main bearing was discolored black, heavily worn, and displaced in the saddle such that the bearing split line did not match up with the case half split line. There was no evidence of lateral lock slot elongation. The oil feed to the backside of the number 4 bearing was unobstructed. The number 5 main bearing was discolored black, heavily worn, and displaced in the saddle such that the bearing split line did not match up with the case half split line. There was no evidence of lateral lock slot elongation. The oil feed to the backside of the number 5 bearing was obstructed by displaced saddle material.

The crankshaft remained intact but displayed thermal distress at the number 1, number 2, and the number 6 connecting rod journals. The number 6 connecting rod journal was also mechanically damaged and the oil feed hole was no longer visible due to the displaced material. Additionally, the crankshaft's number 4 and number 5 main bearing journals displayed black thermal discoloration, along with material displacement at the number 5 bearing journal. All of the crankshaft oil tubes were clear of debris with the exception of the number 6 connecting rod journal, which was mechanically damaged.

The number 1 connecting rod remained secured to the crankshaft and the piston pin; however, it displayed thermal discoloration and evidence of heat distress associated with a lack of lubrication. The oil feed to the number 1 bearing was clear of debris. The connecting rod bearing displayed evidence of thermal discoloration and heat distress associated with a lack of lubrication.

The number 2 connecting rod remained secured to the crankshaft and the piston pin; however, it displayed thermal discoloration and evidence of heat distress associated with a lack of lubrication. The oil feed to the number 2 bearing was clear of debris. The oil feed to the number 2 bearing was clear of debris. The bearing displayed evidence of thermal discoloration and heat distress associated with a lack of lubrication.

The number 3 connecting rod remained secured to the crankshaft and piston pin. There were no signs of operational distress with the connecting rod. The oil feed to the number 3 bearing was clear of debris. The connecting rod bearing displayed some wear, but did not show the signs of thermal distress or lack of lubrication as the others.

The number 4 connecting rod remained secured to the crankshaft and piston pin. There were no signs of operational distress with the connecting rod. The oil feed to the number 4 bearing was clear of debris. The connecting rod bearing displayed some wear, but did not show the signs of thermal distress or lack of lubrication as the others.

The number 5 connecting rod was fractured into four pieces, none of which displayed thermal discoloration; however, mechanical damage was evident on all of the components. The piston end of the connecting rod remained attached to the piston pin. The oil feed to the number 5 bearing was clear of debris. The number 5 connecting rod bearing was liberated along with the fractured connecting rod; however, the two bearing halves were located (one in the sump and one found outside the engine). The bearing was mechanically damaged but there was little-to-no thermal distress noted on the bearing.

The number 6 connecting rod was fractured into five pieces, and all displayed thermal discoloration and mechanical damage. The piston end of the connecting rod remained attached to the piston pin. The oil feed to the number 6 bearing was mechanically damaged at the number 6 connecting rod journal; however, it was unobstructed at the number 4 main journal end. Remnants of the connecting rod bearing were found in the oil sump. The remnants were thermally discolored and distorted.

The internal configuration of two engine crankshaft oil tube assemblies for the number 5 and 6 connecting rods was documented using radiographic images that were collected on May 4 and 5, 2015, in Chicago, Illinois. A total of 360 computed tomography (CT) slice images were examined, processed, and analyzed by the NTSB to evaluate the component. Review of the crankshaft oil tube assembly images determined that there was no indication of low or medium density material buildup on the interior of either the upper or lower oil tube assemblies, a medium density material buildup was noted in areas of the crankshaft outside of the oil tube assemblies, the lower oil tube assembly was deformed on one end, and the other end was completely blocked by high density material with a density similar to the density of the crankshaft material, and the upper oil tube assembly had a discontinuity in the wall area at one end of the tube assembly.

NTSB Probable Cause

A loss of engine power during cruise flight due to the failure of the No. 6 connecting rod, which resulted from oil starvation.