What happened
On June 1, 2021, a Thrush Aircraft S2R-H80, registration C-GWRJ, was performing a ferry flight from Keflavik Airport (BIKF) to Goose Bay, Canada. The aircraft was part of a two-plane formation, having traveled from Kenya via Scotland. To extend the flight's range, a large hopper tank—normally used for agricultural spraying—had been cleaned and integrated into the aircraft's fuel system as a supplemental tank.
During the preflight inspection, the pilot noted droplets in the fuel sample. Although the pilot suspected water, the presence of a fuel scent led him to conclude the sample was pure fuel. Following takeoff from runway 1s, the aircraft began a shallow climb. However, shortly after reaching 500 feet and initiating a right turn, the engine suffered a sudden loss of power accompanied by gray smoke.
Realizing a restart was impossible due to the low altitude, the pilot performed an emergency landing in an open area near the end of the runway. The aircraft sustained severe damage, including a collapsed landing gear and a broken tailwheel, but the pilot escaped without injury.
The investigation
The RNSA examined the aircraft's engine monitor (MVP50) data, which revealed fluctuations in fuel flow and a steady decrease in fuel pressure prior to the engine deceleration. Investigators also inspected the aircraft's fuel system and the fuel truck used for the recent uplift.
While the fuel from the truck was confirmed to meet Jet A-1 specifications, an inspection of the aircraft's fuel filters revealed evidence of corrosion and the presence of water. Samples collected from the engine fuel filter and the aircraft fuel filter drain confirmed water contamination within the fuel system.
Findings
- The primary cause of the engine power loss was water contamination in the fuel.
- The water had accumulated in the wing tanks because the aircraft had recently transitioned from the high temperature and humidity of Kenya to the much colder climate of Iceland. This temperature drop caused dissolved water in the fuel to precipitate out of solution.
- The pilot's preflight sump check had identified droplets that were likely water, but the pilot's assessment that the sample was pure fuel was incorrect.
- The engine was unable to restart because the water contamination prevented a relight once the engine power had already dropped below idle.