What happened
On 6 August 2006, an Aeronca 7AC Champion, registration G-BVCS, was performing a private local area navigation flight from Leicester Airport. Following a successful takeoff on Runway 28, the aircraft experienced a partial loss of power at approximately 100 ft altitude. The pilot responded by momentarily reducing the throttle before returning to full power, which temporarily restored engine performance.
As the aircraft was performing a climbing turn, the engine suffered a total loss of power and stopped. Due to insufficient altitude to reach the alternative runway, the pilot executed a forced landing into a wheat field located ahead and to the right of Runway 10. During the landing roll, the aircraft's main landing gear collapsed. There were no injuries to the pilot.
The investigation
Investigators examined the engine, fuel system, and magnetos. The pilot had previously performed a fuel water test and confirmed that the fuel tanks were full. An engineering inspection by a repair agency found no evidence of mechanical failure or pre-existing damage in the fuel system. However, subsequent testing of the magnetos revealed that one magneto ceased functioning once it reached operating temperature, while the second showed signs of failure before stopping.
Findings
- The investigation determined that the double magneto failure was the most probable cause of the engine failure.
- It is believed the magnetos reached high operating temperatures shortly after takeoff, leading to their sequential failure.
- While the atmospheric conditions (temperature and dew point) indicated a risk of serious carburettor icing, this was considered unlikely because the engine was at full throttle during takeoff and the pilot had successfully tested the carburettor heat prior to departure.