CHI95LA137

The pilot reported that he was cruising at 16,000 feet mean sea level when he heard a loud explosion in the engine compartment and the engine lost power. He descended through instrument meteorological conditions and when he broke out of the clouds, the airport was not in sight and he made a forced landing in a field. A federal aviation administration (FAA) inspector who examined the wreckage reported that the plane was in a wet wheat field and approximately 1000 feet of ground scars led through a ditch to the wreckage. He reported no evidence of preimpact airframe malfunction. Disassembly of the engine revealed the number one connecting rod failed due to fatigue originating from a decarburized layer on the shank of the rod.

On April 26, 1995, about 1234 central daylight time, a Cessna P210N, N4614K, piloted by an airline transport rated pilot, sustained minor damage during a forced landing near Dodge City, Kansas. The pilot and two passengers reported no injuries. Three passengers sustained serious injuries. Instrument meteorological conditions prevailed for the 14 CFR Part 91 flight. The flight originated in Sioux Falls, South Dakota, about 1000 with a planned destination of Amarillo, Texas. An IFR flight plan was filed.

The pilot reported that he was cruising at 16,000 feet mean sea level with the power set at 63 percent. He heard a loud explosion in the engine compartment and the engine lost power. He reported an "engine failure" to the air route traffic control center. The controller vectored the airplane toward Dodge City, Kansas. The pilot reported that he descended through instrument meteorological conditions and when he broke out of the clouds, the airport was not in sight and he elected to land in a field.

A Federal Aviation Administration (FAA) Inspector who examined the wreckage reported that the plane was in a wet wheat field and approximately 1000 feet of ground scars led downwind through a ditch to the wreckage. He reported no evidence of preimpact airframe malfunction.

The engine was examined at the Teledyne Continental Motors Laboratory in Mobile, Alabama, on June 13, 1995. The number one and three cylinders, and the number one connecting rod were previously removed. The number one piston remained in the number one cylinder. The right magneto was broken off at the flange and there was a hole in the top of crankcase over the number one cylinder extending toward the crankcase centerline.

Disassembly of the engine revealed the main bearings exhibited wiping and the number two through six connecting rod bearings were destroyed. The pistons on the right side of the engine had a thin layer of light white colored deposits and the left side pistons had dark colored deposits with a trace of white. The magnetos, fuel pump, throttle control, and manifold valve operated normally when bench tested.

The number one connecting rod was fractured at the junction of the piston pin end and beam section. At the crankshaft end, the cap was spread at the parting surface and the bolts were fractured. A fragment of one bolt remained in the rod.

The number one connecting rod was examined by a materials engineer at the NTSB Laboratory, Washington, D.C. In his factual report, the materials engineer stated the fracture at the piston end of the rod featured "characteristic of a fatigue crack emanated from multiple origins" The surface of the connecting rod shank contained a decarburized layer, .01 inch deep and 0.6 inches wide, that extended partially into the fracture zone.