What happened
On a flight departing from Saint-Hubert Airport, Quebec, a Cessna 172M, registration C-FFRV, experienced a total loss of engine power approximately 15 minutes after takeoff. The aircraft, carrying a pilot and two passengers, was flying under visual flight rules over Montreal when the Lycoming engine stopped. The pilot attempted to restart the engine without success and transmitted a distress message to the control tower. While flying at roughly 1,250 feet, the pilot performed an emergency landing on the northbound side of Parc Avenue. During the touchdown, the left wing tip struck a traffic light post, causing substantial damage to the aircraft. There were no injuries to the occupants.
The investigation
The investigation focused on the fuel system and the conditions present during the preflight inspection. It was determined that the aircraft was not parked on level ground, which prevented the pilot from effectively draining the right fuel tank. Because the aircraft was tilted, water remained below the level of the drain point. Furthermore, the pilot was unable to visually inspect the fuel from the gascolator because the drain valve's location made it difficult to collect the fluid, leading the pilot to drain the fuel directly onto the ground.
Maintenance records were reviewed, showing that the aircraft had been serviced by an approved maintenance organization and had recently undergone a 100-hour overhaul. Investigators also examined the fuel filler caps and found that the right tank's filler cap chain was missing, likely since a 2005 inspection. This missing chain had been exposed to water in the tank, leading to corrosion.
Findings
- The aircraft was not level during the preflight fuel drain, meaning water in the right tank remained below the drain point and could not be removed.
- Water from the right fuel tank migrated into the gascolator bowl, eventually saturating it and causing the engine to stop during a left turn.
- The missing fuel filler cap chain had caused corrosion, contributing to fuel contamination.
- The difficulty of inspecting gascolator fuel due to the valve's location hindered the pilot's ability to detect contamination.
- The aircraft had not been upgraded with additional drain valves as suggested by service bulletin SEB 92-26, which would have facilitated proper drainage of the tanks.