What happened
During a series of landings on a lake, an amphibious float equipped airplane experienced an accident during its third touchdown. The pilot reported completing two successful landings prior to the event. During the third landing, while the aircraft was still "on the step," it executed a hard right turn and subsequently rolled to the left. The aircraft eventually came to rest inverted in the lake. The pilot noted that there were no wind gusts present during the maneuver and confirmed that the manually pumped landing gear had not been cycled between any of the three landings.
The investigation
A Federal Aviation Administration inspector examined the aircraft and found no pre-impact anomalies. Investigators specifically inspected the floats for evidence of damage that would indicate an impact with a submerged object, as the pilot believed striking such an object may have caused the accident. However, no damage consistent with striking a submerged object was identified.