What happened
On 25 February 2012, a Piper PA-38-112 Tomahawk, registration G-BSOT, was conducting a training flight when it experienced a sudden mechanical failure. While climbing at approximately 400 ft agl after departing from Swansea Airport, the instructor heard a loud bang accompanied by intense airframe vibrations and a notable drop in engine power.
In response to the loss of power, the instructor decided to perform an immediate forced landing in a nearby field. The aircraft successfully touched down without further incident, though it was unable to stop before striking a boundary hedge. The impact caused damage to the fuselage and the rudder. Both the instructor and the student remained uninjured and were able to exit the aircraft without assistance.
The investigation
Following the occurrence, investigators examined the aircraft's engine to determine the source of the vibration and power loss. The inspection of the Lycoming O-235-L2C piston engine revealed that a spark plug had failed and detached from one of the cylinder heads.