ANC97LA052

The pilot was in cruise flight at 12,500 feet over mountainous terrain when the engine began to run rough, then it lost power. The pilot selected an emergency landing area on a sand bar. During the landing touchdown, the airplane encountered soft terrain, and sustained damage to the nose wheel, right main landing gear, and the right wing. A postaccident examination of the engine revealed a hole in the engine case at the number 2 cylinder. The number 2 connecting rod was found bent, and the rod bolts were broken. The connecting rod bearing displayed discoloration from high temperature.

On April 10, 1997, about 0920 Alaska daylight time, a Piper PA-28, N6472R, sustained substantial damage during a forced landing about 58 miles north of Port Alsworth, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The certificated airline transport pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. A VFR flight plan was filed. The flight originated at the Anchorage International Airport, Anchorage, Alaska, at 0754.

On April 11, 1997, the pilot reported in a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), that he was in cruise flight at 12,500 feet mean sea level. The sound of the engine changed slightly, and it began losing RPM. The pilot applied carburetor heat and enriched the fuel mixture, and the engine stabilized for a few minutes at 2300 RPM. The pilot then noticed an engine vibration, and smoke was observed emanating from the engine cowling. The engine quit running, and the pilot declared an emergency at 0856. The pilot performed an emergency landing near a frozen lake known as Two Lakes, located on the north side of the Alaska Mountain Range. The pilot selected a sand bar along the edge of the lake, and during the touchdown, the landing gear dug into soft sand. The airplane received damage to the nose gear and left main landing gear.

The pilot indicated his examination of the airplane after landing revealed a coating of oil on the underside of the airplane. After retrieval, the airplane engine was examined by a mechanic, and an airworthiness inspector with the Federal Aviation Administration. The examination revealed a hole in the engine case, above the number 2 cylinder. Internal damage to the engine prevented the removal of the number 1, and number 2 cylinders. The number 2 connecting rod was bent, and the connecting rod bolts were broken. The number 2 rod bearing exhibited visual signs of heat discoloration at the connecting rod journal. The oil pump was intact. No other abnormalities were observed.

The pilot said the engine was last inspected during a annual inspection on September 22, 1996, 30 service hours before the accident. At that time, the number 2 and the number 4 cylinders were replaced.