A float-equipped DHC-3T Turbine Otter operated by Blue Water Aviation Services, was conducting a flight from Bissett (CJY6), MB to Family Lake near Little Grand Rapids, MB with 1 pilot and 2 passengers and approximately 800 pounds of freight on board. The purpose of the flight was to transport 2 contractors, their tools, and some roofing materials. It was the first of a series of flights planned for that day. As the aircraft was turning final for the water at Family Lake the right wing became detached from the fuselage. The aircraft entered an uncontrolled descent and collided with the water surface. The pilot and 2 passengers sustained fatal injuries. Findings as to causes and contributing factors 1. A fatigue fracture originated in the bolt hole bore of the right-hand wing lift strut’s upper outboard lug plate, and eventually led to an overstress fracture of the right-hand wing lift strut’s upper outboard and inboard lug plates during the left turn prior to the final approach. 2. The failure of the outboard and inboard lug plates led to the separation of the right-hand wing lift strut from the wing and, subsequently, the separation of the right wing from the aircraft.