Event Overview
On the third flight of the day, a Beech 18 seaplane was departing a fishing camp at Bradburn Lake, Manitoba, for the operator's base in Selkirk. After boarding passengers and loading baggage, the pilot taxied the aircraft to a position near the southwest shore of the lake and commenced the take-off run on an approximate heading of 015° true.
Sequence of Events
During the take-off run, after the aircraft was "on the step," the pilot noticed a yaw to the left. He corrected the yaw using the rudders and differential engine power. Shortly thereafter, at about 60 miles per hour, the yaw recurred and worsened. The left float then separated from the aircraft, and the left wing struck the water. The aircraft turned sharply to the left, stopped in the water, and came to rest on its left wing tip in approximately 15 feet of water.
Aftermath
The pilot and the six passengers were not injured. They exited the sinking aircraft and swam to shore. The accident occurred at 1040 central daylight saving time during daylight hours at latitude 51°55'N and longitude 95°35'W.
Probable Cause
According to the official findings, the left front swivel fitting attachment bolt probably moved out of position because the securing nut was either not installed or came off in service. A series of failures ensued, culminating in the separation of the left float from the aircraft.