On April 24, 1998, about 2140 Alaska daylight time, a tundra tire equipped Cessna 170B airplane, N2692D, sustained substantial damage during a forced landing, about 44 miles west of Kenai, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The airplane was registered to, and operated by the pilot. The certificated private pilot, and the sole passenger, were not injured. Visual meteorological conditions prevailed. The flight originated from a remote airstrip about 2040. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on April 27, 1998, at 0800, the pilot reported he departed Keys Point at Lake Clark, Alaska, and was flying through Lake Clark Pass. While in cruise flight, the oil pressure began to decrease to below the normal operating range. The pilot began a climb to 3,500 feet mean sea level. The engine then began to run rough, and the pilot shut the engine off. He made an emergency landing in a small open area. The airplane touched down in snow covered terrain, and then nosed over. The airplane received damage to the left wing spar, the rudder, and the leading edge of both wings. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office (FSDO), Anchorage, Alaska, examined the airplane engine on April 29, 1998. The inspector reported the number six piston connecting rod bearing was destroyed. The connecting rod cap was also destroyed. The number six crankshaft rod bearing journal was blackened and battered. The pilot reported the engine had accrued a total time of 4,417.28 hours. It had accrued 1,274.18 hours since an engine overhaul. The most recent inspection was an annual inspection conducted on November 28, 1997, 13.65 hours before the accident.