19980619019709A

Losing oil pressure diverted for 4Z4. Lost power 3 mi short. Landed sandbar sheared nose gear. Wings hit trees. (.4)the certificated airline transport pilot, and three passengers departed on an air taxi flight over remote terrain. While in cruise flight about 2,200 feet, the engine oil pressure began to drop, and the engine oil temperature began to rise. The pilot decided to divert to the nearest airport. The engine quit running, and the pilot selected an emergency landing area on a sand bar along a river that contained several willow trees. During the landing, the airplane recieved damage to the wings and fuselage. The engine had accrued 1,491 hours since an overhaul. During that time, seven engine cylinder changes were performed by company maintenance personnel. An examination of the engine revealed the crankshaft was broken along the aft, lower dege of the number two cheek journal. The fractrue line was straight and flat, through the full dimension of the number two cheek journal, and was oriented perpendicular to the longitudinal axis of the crankshaft. The number two main bearing was broken and flattened. The number two main bearing saddle was flattened and distorte d. the left and right engine case halves mating surface exhibited galling/fretting at the number two main journal bolt holes. (-23) the aircraft was on a charter flight, enroute from grayling, AK to bethel, AK. Approximately 30 miles west of Holy Cross, AK, the pilot noticed a gradual drop in oil pressure and rise in oil temperature. The pilot proceeded to divert to Holy Cross. Approximately 2 miles north of Holy Cross, the engine seized and the pilot executed an emergency landing on a sand bar. Upon landing, the aircraft rolled through willow trees, causing substantial damage.