Introduction
On 19 May 2014, a Cessna 152 (registration G-BHYX) operated as a private flight experienced a loss of engine power while cruising at approximately 2,300 ft. The aircraft, manufactured in 1978 and equipped with a single Lycoming O-235-L2C piston engine, was forced to land in a field near Westfield Farm, located 7 miles south-southwest of Cranfield Airport.
History of the Flight
The pilot, who held a Private Pilot’s Licence with 173 total flying hours (165 on type), was approximately 45 minutes into the flight when the engine began to run roughly and the rpm decreased slowly. After verifying normal engine indications and a rich mixture setting, the pilot reported applying carburettor heat for 15 to 20 seconds. The engine rpm decreased when carburettor heat was selected on and recovered when it was turned off.
Three to four minutes later, the engine rpm reduced again, and the pilot could not maintain altitude. The throttle was moved fully forward, magnetos were confirmed in the 'both' position, and the fuel primer pump was closed and locked. A MAYDAY call was made to Cranfield Approach, which had been providing a Basic service. The pilot positioned the aircraft for a field landing but noticed telegraph poles in the selected field and redirected to a second field.
During the approach, the aircraft touched down approximately one-third of the way along the field. The pilot was unable to stop before the aircraft ran into bushes and a ditch at the field boundary.
Damage and Injuries
The accident resulted in damage to the propeller, fuselage, engine mounting frame, engine cowlings, front and rear screens, rudder, and tailplane. The nose landing gear also sustained damage. The pilot and the single passenger were not injured.
Carburettor Icing Considerations
The pilot reported an outside air temperature of 24°C and a dew point of 12°C. 'FREDA' checks had been performed frequently, with carburettor heat applied by the passenger (also a qualified pilot) for 15 to 20 seconds. According to the CAA Safety Sense Leaflet 14, these conditions would have posed a moderate risk of carburettor icing during the cruise. The CAA advises that carburettor heat should be applied for at least 15 seconds to prevent and clear icing. However, the cause of the engine power loss was not established.
Conclusion
The investigation determined that the cause of the loss of engine power was not established. The pilot conducted a forced landing, resulting in damage to the aircraft but no injuries to the occupants.