What happened
On 4 October 2006, a Yak-52, registration G-YKYK, was conducting a private flight intended for practicing formation and tactical maneuvers alongside three other aircraft. While cruising at 1,500 ft in clear weather conditions, the aircraft's engine suddenly lost power. During the descent, the pilot attempted to restore power by pumping the fuel primer, which provided only momentary bursts of engine power before failing again.
The pilot eventually handed control to the rear seat occupant to focus on cockpit checks. The rear seat pilot transmitted a distress message to a nearby aircraft before the fuel was switched off. The pilot then selected a field at Stockhall Farm, Ulmost, Maldon, for an emergency landing. As the aircraft approached the ground at approximately 50 ft, the pilot switched the magnetos to the OFF position. The aircraft struck the ground in a ploughed field, making contact with the field margin via the landing gear. The impact caused damage to the propeller and the trailing edge of the flaps. There were no injuries to the two crew members on board.
The investigation
Investigators examined the aircraft's engine and electrical systems following the incident. Post-accident testing revealed that the magneto system was malfunctioning. This failure was traced to a broken accessory drive shaft within the engine. While the specific cause of the shaft's failure was to be determined during a future engine overhaul, the investigation noted that such a drive shaft issue had not been previously recorded with UK-based aircraft of this type.