What happened
On a flight returning to Orillia, Ontario, a float-equipped Cessna 185F, registration C-GAXK, experienced a series of engine power fluctuations. After departing from a remote fishing camp approximately 21 miles east of its destination, the aircraft climbed to 1,000 feet before the engine lost power. The pilot attempted to restore power by adjusting the mixture to full rich and activating the auxiliary electric fuel pump, which successfully stabilized the engine.
However, the engine lost power again immediately after the pilot deactivated the auxiliary pump. Despite further attempts to troubleshoot by applying full throttle, switching fuel tanks, and re-engaging the auxiliary pump, the engine failed to regain power. The pilot subsequently performed an emergency landing in a wetland area. During the landing, the aircraft struck a tree, causing substantial damage to the aircraft and resulting in one minor injury to a passenger. All occupants were safely evacuated by search and rescue.
The investigation
Investigators examined the engine, electrical systems, and fuel components. The Teledyne Continental IO-520-D engine had approximately 480 hours since its last rebuild. While fuel samples from the gascolator showed no contamination, investigators discovered that the engine-driven fuel pump (EDP) was malfunctioning. Specifically, testing revealed that the pump could not maintain both required fuel flow and pressure simultaneously.
Furthermore, the investigation into the electrical system revealed that the auxiliary fuel pump's operation had become unreliable. The wiring connecting to the resistor block exhibited corrosion, which caused minimal contact and led to intermittent functionality.