What happened
On 3 July 2005, a Cessna 152, registration G-IRAN, was conducting a private local flight from Andrewsfield, Essex. During the return leg of the flight, while descending from 2,500 ft to 1,500 ft, the engine experienced an abrupt loss of power. The pilot attempted to restart the engine by applying carburettor heat, verifying a rich mixture, and selecting both magnetos, but the engine failed to restart.
Recognising the low altitude, the pilot performed a forced landing into a field of standing wheat. During the landing attempt, the pilot attempted to maintain a low altitude of approximately two feet above the crops to reduce the impact. However, the main wheels became entangled in the wheat, causing the nose wheel to dig into the ground. The aircraft subsequently flipped over and came to rest in an inverted position. The pilot, who sustained no injuries, exited the aircraft through a door. The aircraft suffered extensive damage to the engine frame, propeller, nose leg, fin, and left tailplane.
The investigation
The investigation examined the engine and the meteorological conditions at the time of the accident. An inspection of the engine at the crash site revealed that the carburettor heat control was fully in the 'on' position, meaning no heat was being provided to the carburettor. The engine showed no leaks, and the oil level was within limits. There were no visible defects in the ignition components or control cables. Subsequent testing by an independent maintenance organisation found the engine to be functional, producing power within 5% of the maximum allowed limits.
Meteorological data indicated that the area was covered by a moist, west-south-westerly airflow. At the time of the incident, the temperature was approximately 17.6°C with a humidity of 78%.
Findings
- The engine failure was likely caused by carburettor icing.
- Atmospheric conditions were consistent with the potential for icing, as the temperature and humidity levels fell within the range where icing can occur even in warmer weather.
- The pilot had used carburettor heat at least once prior to the failure, suggesting the issue was not an immediate mechanical defect but a result of environmental factors.