What happened
On a geophysical survey flight near Saskatoon, Saskatchewan, a CASA C-212-CC40 (registration C-FDKM) experienced a catastrophic sequence of engine failures. While operating under visual flight rules, the aircraft's right engine lost power, prompting the crew to shut it down and begin an approach to Runway 27 at Saskatoon/Diefenbaker International Airport. During this final approach, the left engine also lost power, forcing the crew to perform an emergency landing adjacent to Wanuskewin Road. The aircraft struck a concrete noise abatement wall and was destroyed. The accident resulted in one fatality and two injuries.
The investigation
The investigation focused on the mechanical failure of the right engine and the subsequent loss of the left engine. Laboratory analysis of the right engine revealed that improper case hardening in the torque sensor gear train led to excessive wear and fatigue cracking in an intermediate spur gear. This failure caused the gear to fragment, disrupting power transmission to the high-pressure engine-driven fuel pump and resulting in fuel starvation.
Regarding the left engine, investigators found that foreign object debris (FOD) had become lodged in the nozzle of the No. 2 ejector pump. This debris compromised the pump's ability to transfer fuel from the wing to the collector tank. Additionally, the investigation examined why the crew did not notice the left fuel level warning light and why the survey equipment (known as "birds") remained deployed, which hindered the aircraft's climb performance during the initial engine failure.
Findings
- The right engine failed because an intermediate spur gear in the torque sensor gear train fractured, causing fuel starvation.
- The left engine failed due to fuel starvation caused by the depletion of the collector tank.
- The delivery of fuel from the left wing to the collector tank was restricted by foreign object debris (FOD) in the No. 2 ejector pump nozzle.
- The crew did not execute fuel-related checklists because they did not perceive the illumination of the left fuel level warning light.
- The decision to keep the survey sensors deployed for several minutes after the first engine failure reduced the aircraft's ability to climb effectively.
Safety action
- Fugro Aviation Canada Ltd. updated its single-engine emergency procedures to include opening the fuel crossfeed valve to utilize both tanks.
- The operator installed a remote-controlled cable cutter to allow pilots to jettison survey equipment from the cockpit.
- Honeywell Aerospace revised the torque sensor maintenance manual to require magnetic particle inspections of the spur gear.
- Airbus Military updated the airplane flight manual with additional cautions and procedural steps regarding engine failure and fuel management.