What happened
On 3 January 2009, a Flight Design CT2K, registration G-CBNA, departed from a farmstrip near Hook Norton, Oxfordshire, for a local flight. The flight was conducted in cold conditions, with surface temperatures recorded at -2°C. While cruising at 2,500 ft, the aircraft's engine suddenly ceased operation. Although the pilot attempted to restart the engine and noted that it continued to turn over and fire, the power failure persisted.
With the engine non-operational, the pilot performed a forced landing in a nearby field. During the landing roll, the aircraft encountered an uneven, frozen ground surface, which caused the nosewheel assembly to fail and the aircraft to roll over. The pilot escaped the wreckage without no injuries, though the aircraft sustained significant damage, including a cracked left wing, damage to the fin, a broken engine mounting, and damage to the propeller and nosewheel.
The investigation
Investigators examined the engine and fuel system at a repair agency. Engineers discovered rust within the gascolator, which indicated that water had been present in the fuel system at some point. However, the fuel tanks had been drained before the aircraft was moved for repairs, and no fuel samples were available for laboratory analysis.
Regarding the engine's design, the aircraft utilized conventional carburettors. This specific model lacks a dedicated carburettor heat system, instead relying on the ambient temperature of the air passing beneath the engine cowls to prevent ice buildup. The pilot noted that the cabin heat had been set to a high level during the flight, which may have diverted heat away from the engine area.
Findings
- The primary cause of the engine failure was likely fuel starvation or carburettor icing.
- The presence of rust in the gascolator suggests that water may have entered the fuel system, potentially due to condensation forming in the cold weather.
- If water was present, the freezing temperatures could have caused a blockage in the fuel supply.
- While carburettor icing remains a possible factor, it is considered less likely given the engine's reliance on ambient air temperature for ice prevention.