What happened
On a flight departing from Long Haul Lake, Manitoba, a de Havilland DHC-3 seaplane experienced a sudden and total loss of engine power during its takeoff roll. The aircraft, registered as C-FIFP, was operated by Blue Water Aviation Services and was carrying a pilot and an aviation maintenance engineer. Shortly after the engine failed, the aircraft lost altitude and struck a stand of trees before hitting the ground at a steep angle. The impact caused a small fire in the carburettor and destroyed the aircraft.
The crew had previously experienced an engine power loss during an earlier attempted departure from the same location on the same day. Following that first incident, the crew had drained the fuel sumps, discovered water, and flushed the fuel system. After performing successful engine checks, they attempted the second takeoff using fuel from the centre tank. However, the engine failed again at an altitude of approximately 100 to 150 feet, leaving the pilot with insufficient space to reach open water.
The investigation
Investigators examined the wreckage and the engine components to identify any mechanical or electrical failures. The investigation found no evidence of pre-existing structural defects, electrical malfunctions, or mechanical issues within the engine, propeller, or accessories. While the magneto timing was found to be outside of required limits, it was determined that this was not a factor in the power loss.
Testing of the fuel system revealed traces of water and rusty deposits in the carburettor screens, fuel lines, and the main fuel filter. Although the source of the water could not be determined, the presence of contamination was confirmed in the centre tank's forward sump drain. The investigation also noted that the engineer was wearing a lap belt but not the available shoulder harness, whereas the pilot was fully restrained.
Findings
- The most likely cause of the engine power loss was water contamination migrating from the centre fuel tank into the engine.
- The engine failed at a point where a safe landing on the lake was no longer possible.
- The engine power loss during the first attempted takeoff of the day was also likely caused by fuel contamination.
- The post-impact fire in the carburettor was likely fueled by clean fuel moved into the area by the pilot's attempts to clear the system and the windmilling engine.
- The engineer's injuries likely would have been less severe had he been wearing his shoulder harness.