What happened
On 9 November 2005, a Pegasus Flash, registration G-MNGF, was conducting a private flight from a hangar in Great Oakley, Essex. Following a period of engine warm-up and pre-flight inspections, the pilot taxied to Runway 27 for takeoff. The aircraft climbed normally, reaching an altitude of approximately 200 feet with a climb rate of 600 fpm.
At this height, the engine suddenly cut out without warning. The pilot, unable to use the ploughed field directly ahead due to its unsuitable surface, attempted to land on the crosswind runway, Runway 22. However, the aircraft's low altitude prevented the completion of the turn. The pilot instead attempted a downwind landing on a taxiway. During the landing, the nose wheel sank into the soft ground, causing the aircraft to somersault about its nose. The impact resulted in extensive damage to the fuselage, landing gear, and wing. The pilot sustained minor injuries and was able to exit the aircraft without assistance.
The investigation
The AAIB examined the engine and ignition systems to determine the cause of the sudden power loss. The investigation noted that the engine had experienced a momentary cutout during a previous flight, which had prompted the pilot to clean the points and inspect the fuel system. The investigators also considered the possibility of carburettor icing; however, because the engine failed abruptly and without warning, this was ruled out. Additionally, the possibility of a simultaneous failure of both high tension ignition circuits or a failure of the ignition switch was dismissed due to the nature of the power loss.
Findings
- The engine failure was caused by an internal defect within the magneto generator.
- This defect led to a total loss of power to the engine ignition system.
- The engine's magneto generator, which provides electric power via three coils, was susceptible to insulation breakdown.
- The investigation noted that high-time Rotax 447 engines have previously experienced total power loss due to the breakdown of 'Shellac' insulation in the low power magneto coils caused by overheating.