Accident Details
An airline transport pilot, accompanied by two passengers, was conducting an aerial timber survey. While flying in cruise at approximately 1,000 feet above ground level, the engine began to backfire, run roughly, and lose power. Subsequently, the engine ceased operating. The pilot identified a gravel bar along a glacial-fed river as a suitable emergency landing area.
During the emergency approach, the airplane did not reach the intended landing site. It touched down in about 3 feet of water and nosed over. The aircraft was later recovered for examination.
Post-Recovery Examination
An FAA airworthiness inspector examined the airplane after recovery. The inspector noted that the number seven cylinder was cracked, and the number nine cylinder had no compression. Additionally, approximately one cup of clear water was found within the carburetor float bowl.
The inspector reported that he could not determine whether the cylinder damage or the presence of water in the carburetor resulted from impact with the river water during the accident.
When the engine was subsequently disassembled, the number nine cylinder head was found separated from the cylinder barrel.