SONORA, CA, USA
N214MS
Beech A36TC
The flight was level at 17,500 feet msl when 40 minutes into the flight the engine began to run extremely rough. This lasted for about 10 to 15 seconds when the engine abruptly stopped. Postaccident examination of the engine revealed that the number 1 connecting rod failed causing a catastrophic failure of the engine. Subsequent examination of the engine revealed that the number 1 main bearing oil supply hole had been blocked from supplying oil to the number 1 connecting rod. Examination of the number 1 main bearing halves revealed that there were operational movements indicated on a bearing half. Evidence was found to indicate the half had fractured/disintegrated and blocked the oil supply hole. The number 1 connecting rod then failed from oil starvation.
On June 2, 1996, about 1140 hours Pacific daylight time a Beech A36TC, N214MS, was substantially damaged during a forced landing near Sonora, California. Visual meteorological conditions prevailed for the personal cross-country flight and no flight plan was filed. The pilot and passenger received minor injuries. The flight originated at Reno, Nevada, on the day of the accident destined for Lancaster, California. The pilot reported that they were in level flight at 17,500 feet msl. About 40 minutes into the flight the engine began to run extremely rough. This lasted for about 10 to 15 seconds when the engine abruptly stopped. A postaccident examination of the engine revealed that the number 1 connecting rod failed at the crankshaft. The failed rod components/pieces were sent to the Safety Board Materials Laboratory Division for examination. According to the examination of the submitted pieces, they had all been subjected to extensive post-separation mechanical and heat damage. Examination of the limited undamaged portions of the fractures revealed features typical of over stress separation. The entire engine was shipped to the manufacturer's facility at Mobile, Alabama. The engine was subjected to additional analysis under FAA oversight. According to the report, the number 1 main bearing oil supply hole had been blocked from supplying oil to the number 1 connecting rod. The rod failed due to oil starvation. One half of the number 1 main bearing revealed evidence of operational movement leading to a fracture/disintegration of the bearing half.
failure of the number 1 connecting rod due to oil starvation caused by inadequate bearing crush.
Source: NTSB Aviation Accident Database
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