What happened
On 11 January 2019, a Nipper T.66 RA45 Series 3, registration G-AXLI, was conducting a private flight near Norton St Philip, Somerset. After departing from Brown Shutters Farm for general handling, the pilot began a descent from just below 4,000 ft. While attempting to increase the throttle to maintain engine warmth, the engine power ceased abruptly.
As the aircraft glided at approximately 60 mph, the propeller began a slow rotation. In an attempt to restore power, the pilot increased the airspeed to 120 mph by pitching down. However, the engine failed to respond. While attempting a straight-in approach to the farm's runway, the aircraft encountered a high sink rate and the risk of striking power lines. To avoid the wires, the pilot executed an S-turn and sideslip to land in a nearby field. Upon impact, the soft ground caused the aircraft to flip and become completely inverted. The pilot, who sustained no injuries, managed to exit the wreckage through a gap in the shattered canopy.
The investigation
The investigation examined the engine's failure and the environmental conditions at the time of the accident. Meteorological data indicated a temperature of 8°C and a dewpoint of 5°C. The investigation focused on the likelihood of ice formation within the engine's carburettor during the flight.
Findings
- The engine power loss was likely caused by carburettor icing.
- Atmospheric conditions, specifically the temperature and humidity levels, were consistent with high-probability icing conditions for a carburettor at cruise power.
- The pilot's attempt to regain engine power by increasing airspeed resulted in a loss of altitude that prevented a successful return to the airfield.