On September 3, 2018, about 1353 Alaska daylight time, a Piper PA-32 airplane, N3957X, sustained substantial damage when it was involved in an accident near Wrangell, Alaska. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, while in level cruise flight, the engine rpm increased from a cruise power setting of 2,300 to 3,100, and he reduced the manifold pressure to correct for the high rpm. Shortly thereafter, he noticed the engine oil pressure drop and oil visible on the airplane’s windscreen, followed by a total loss of engine power. He performed an emergency landing near the high tide line in an area of seagrass. During the emergency landing, the airplane sustained substantial damage to the fuselage and left wing. The airplane was equipped with a Lycoming IO-540-K1G5 engine. Examination of the engine revealed a large fracture hole near the Nos. 4- and 5-cylinder pads. The Nos. 4 and 5 connecting rods were fragmented, and pieces of the connecting rods and a large amount of metal debris were located within the engine and oil suction screen. The Nos. 4 and 5 connecting rods and rod bearing journals exhibited extensive mechanical damage and signatures consistent with extreme high heat. The engine oil pump was intact with no evidence of thermal damage. The engine case halves displayed mechanical damage with multiple protrusions from the inside out. When the oil sump was removed, damaged connecting rod ends and a large amount of metal debris were discovered. The pilot reported that the oil filter element had not been cut and examined at the last oil change, contrary to Lycoming Mandatory Service Bulletin No. 480F.