What happened
On 13 July 2008, a North American P-51D-20 Mustang, registration G-BIXL, experienced significant engine issues while operating at Duxford Airfield, Cambridgeshire. The aircraft suffered from rough running and a subsequent loss of engine power.
The investigation
Investigators examined the engine's electrical system to determine the origin of the power loss. The inquiry established that the engine's windings had become overheated, which triggered an electrical short circuit. This specific failure mode had been observed intermittently prior to the accident.
During post-accident testing, the investigation revealed further complications within the ignition system. The left magneto ceased functioning entirely after 20 minutes of operation. Additionally, the right magneto exhibited intermittent performance after 90 minutes. It was determined that both magnetos contained faults that caused them to operate normally only after a period of cooling.