Incident
A float-equipped de Havilland Canada DHC-3 Otter departed a company water base in Cochenour, Ontario, on a charter flight to Sandy Beach Lodge on Trout Lake, approximately 25 nautical miles east. The aircraft carried the pilot and six passengers. After leveling at about 2,500 feet above sea level and configuring for cruise, the pilot heard a popping sound, noted a slight loss of engine power, and observed wisps of whitish-grey smoke entering the cabin. Engine instruments indicated normal operation, and the fire warning system did not activate. Suspecting a cylinder failure, the pilot initiated a turn back toward Cochenour.
A passenger in the right front crew seat reported seeing flames near the floor at the front, right corner of the cockpit. The pilot radioed the Thunder Bay Flight Service Station to declare an emergency, asked the passenger to vacate the crew seat, and attempted to suppress the fire with a hand-held extinguisher. Thick, black smoke quickly filled the cabin, reducing visibility and causing respiratory distress for all occupants. The pilot opened the left crew door to see ahead and then landed the still-burning aircraft on McNeely Bay, the first available landing site.
Emergency Response
The aircraft touched down hard but remained upright on its floats. All seven occupants evacuated through the main door, donning life jackets, and were picked up almost immediately by nearby boats. The aircraft was completely consumed by fire within minutes after landing.
Damage and Injuries
The aircraft was destroyed by fire. The pilot sustained second-degree burns to his face and right forearm. The passenger in the right front crew seat suffered burns to his right leg. The remaining five passengers escaped serious injury.
Probable Cause
The official investigation determined that continued operation of the engine following an exhaust valve failure on the number 2 cylinder resulted in a flaming gas path near the right side of the firewall, an exhaust system overheat, and a subsequent cabin fire.