What happened
On June 13, 2008, a Cessna 337D, registration C-GYHW, was returning to Buffalo Narrows, Saskatchewan, after a passenger drop-off at Stony Rapids. During the return leg, approximately 14 miles northeast of the destination airport, the aircraft experienced a simultaneous loss of power in both engines. The pilot declared an emergency and performed a forced landing in a swampy area on the east shore of Churchill Lake. The aircraft sustained substantial damage, but the pilot escaped with minor injuries.
The investigation
Investigators examined the wreckage and found that the propellers were not operating at the moment of impact. While the auxiliary fuel tanks were full, the main tanks were completely empty. The investigation established that the pilot had not utilized the auxiliary fuel supply during the flight, believing the main tanks contained enough fuel to complete the trip. When the engines lost power, the pilot attempted to use the auxiliary boost pumps, but because the fuel selectors were not properly configured, the pumps could not draw from the auxiliary tanks.
Further review of the aircraft's fuel system revealed that the auxiliary pumps are designed to only pull from the main tanks. To access the auxiliary supply, a specific sequence must be followed. The investigation also looked into the pilot's experience, noting he was a new hire who had completed initial company training only one day prior to the accident and had very limited time on this specific aircraft type.
Findings
- The pilot's calculations regarding the fuel required for the round trip were incorrect, leading to the depletion of the main tanks.
- The pilot lacked a sufficient understanding of the fuel system's operation, specifically the procedure required to access the auxiliary tanks.
- The operator's training program failed to adequately test or establish the pilot's proficiency in managing the aircraft's complex fuel system.
- The design and naming conventions of the fuel system, including the overhead selector location, increase the risk of pilot error during high-workload emergencies.