Primary finding
Probable cause
The airplane’s collision with a submerged log during a water landing.
Investigator assessment
Analysis narrative
The flight instructor and pilot receiving instruction were completing water landings in the amphibious airplane. They had already completed several landings on the same pond without incident. During the accident landing, upon touchdown the airplane impacted a submerged log, which punctured a large hole in the hull. The pilots egressed without further incident and the airplane sank. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.