What happened
On 9 December 2018, a Slingsby T61F Venture T Mk 2, registration G-BUGT, was performing a private flight departing from Runway 35 at Rufforth Airfield. During the wait for the runway to clear, the pilot engaged the carburettor heat. Once the runway was vacant, the pilot lined up and applied full throttle without coming to a complete stop.
While climbing at an altitude of approximately 150 to 20 and 200 feet, the aircraft suffered a complete loss of engine power. The pilot initiated a forced landing in a field near the airfield boundary. During the landing sequence, the pilot attempted to hop the aircraft through a gap in the vegetation, but the wings struck bushes. The aircraft sustained damage to the wings, which were twisted and broken, along with damage to one propeller blade and the rear fuselage. There were no injuries to the pilot.
The investigation
The investigation focused on the cause of the engine failure and the state of the aircraft systems. Upon inspection of the engine and related components, investigators found no mechanical faults capable of causing a total loss of power.
Testing conducted on two other Slingsby Ventures demonstrated that while applying full carburettor heat caused a significant drop in RPM (up to 600 rpm) and could lead to rough running that prevented climbing, it did not result in a total engine failure. In those test cases, engine power was fully restored once the heat was turned off. Following the accident, the pilot noted that the carburettor heat remained in the 'on' position.
Findings
- The pilot failed to verify the position of the carburettor heat during the final checks before takeoff.
- The selection of carburettor heat during the takeoff roll was the primary factor in the engine's performance degradation.