What happened
On an evening during firefighting operations near Hornepayne, Ontario, a de Havilland DHC-6-300 (registration C-GOGC) was performing water scooping maneuvers on Lake Wicksteed. The pilot was executing the third collection run of the mission, approaching the lake from the east in light winds. After touching down on the water, the pilot observed water overflowing from the float tanks, signaling they were full. Upon pressing a button on the flight yoke to retract the probes, the aircraft suddenly nosed into the lake in a wings-level position and began to submerge.
The pilot managed to exit the sinking aircraft and clung to the side of the partially submerged float until a witness arrived in a boat to assist. While one witness sought emergency services in Hornepayne, the pilot was moved to a nearby cottage for safety. The aircraft eventually settled upside down on the lakebed, with its floats protruding above the water surface. There were no fatalities and no reported injuries.
The investigation
Investigators examined the hydraulic and electrical systems responsible for the aircraft's water-collection components. The aircraft, operated by the Ministry of Natural Resources (MNR), utilizes modified Wipline 13000 amphibious floats equipped with probes and water bomb doors. These components are operated electro-hydraulically via two side-by-side buttons on the left yoke. The investigation focused on the state of the door-arming switch and the physical condition of the cockpit controls.
Findings
- The pilot failed to complete the full Vital Action checklist during the approach, which resulted in the bomb door armed switch remaining in the ON position from a previous mission.
- The pilot accidentally pressed the bomb door switch instead of the probe switch due to their close proximity on the yoke.
- The bomb door push-button switch lacked its protective hinged cover, which had not been reinstalled following recent maintenance, significantly increasing the risk of accidental activation.
- Because the system was armed, the bomb doors deployed into the water, creating massive drag and allowing water to flood the openings, which caused the aircraft to nose over.