What happened
On 17 December 2006, a private flight involving an X’Air R100, registration G-CBPU, was en route from Tatenhill Airfield to Long Marston Airfield. The weather conditions were favorable, with a surface wind of 280º at 10 knots. While cruising at approximately 1,800 ft amsl, the pilot experienced a sudden 50% reduction in engine power.
Following the loss of power, the pilot declared a ‘Mayday’ and identified a suitable field for an emergency landing located at the top of a hill, roughly 400 ft amsl. To maintain sufficient lift and manage the aircraft's high sink rate, the pilot opted not to reduce power to idle. However, during the final approach, the engine ceased functioning entirely, causing the aircraft to land short of the intended target. The aircraft entered an undershoot field and continued along the landing roll until it struck a hedge separating the two fields. The impact resulted in moderate damage to the nose wheel, the left mainwheel, and the pod. There were no injuries to the pilot or the single passenger on board.
The investigation
The investigation focused on the cause of the engine power loss. The pilot reported noticing low battery voltage during the flight prior to the engine failure. Technical examination revealed that the aircraft's alternator had developed faults. Because the engine's ignition, timing, and fuel pump systems rely on the alternator and battery to maintain proper operation, the electrical failure directly impacted engine performance.