Incident Overview
The pilot of an amphibious airplane reported a normal approach to landing on near glassy water conditions. Shortly after contacting the water, the right sponson detached, and the right wing struck the water, causing the airplane to rotate 180 degrees and come to a stop. The pilot attempted to water taxi toward shore, but the cabin began flooding. Before reaching land, the pilot and a passenger decided to evacuate and boarded a boat that had arrived to assist. The airplane sank after the occupants evacuated.
Post-Accident Findings
During a post-accident interview, the pilot stated that "the right wing may have dipped" during landing and reported "significant damage" to the right wing flap after the sponson separated at touchdown. The airplane was later recovered, but the right sponson was not found. A Federal Aviation Administration Aviation Safety Inspector observed damage to the right wing at the wing root and noted that the sponson detachment did not appear to be due to any design or assembly issue.
Mechanical Status
The pilot reported no mechanical malfunctions or failures with the airplane that would have precluded normal operation. The airplane sustained substantial damage to the right wing and fuselage.