What happened
On 17 July 2004, a North American P-51D-20, registration G-BIXL, was returning to its home airstrip near East Garston, Berkshire, following a flying display. The flight, conducted as a private operation, included a series of low-altitude aerobatic manoeuvres over the airfield. During a climbing phase following a right-hand roll, the engine suddenly lost power at an altitude of less than 1,000 feet.
As the aircraft climbed, the pilot attempted to restore power by switching the fuel selector from the left tank to the right tank. When the engine failed to restart, the pilot transitioned the propeller to full coarse pitch. As the aircraft's airspeed decayed, the pilot determined that returning to the airstrip was unlikely and instead navigated toward a valley to find a suitable landing site. While attempting to recover airspeed, the engine emitted loud backfiring sounds. The pilot eventually identified two fields and performed a forced landing in a tall crop of broad beans. There were no injuries to the single occupant.
The investigation
Investigators examined the aircraft and its fuel system to determine the cause of the power loss. While the maintenance organisation could not find a definitive mechanical fault, the pilot's description suggested fuel starvation. Testing of the fuel and filters revealed no water or blockages.
At the time of the landing, the fuel gauges showed 17 US gallons in the left tank and 55 US gallons in the right tank. The investigation noted that the pilot had been flying solely on the left tank during the aerobatic sequence. The examination also noted that the engine's manifold pressure had fluctuated during the descent, and the propeller blades were bent rearwards from the impact.
Findings
- The engine power loss was likely caused by a brief period of fuel starvation.
- This starvation was probably triggered by the aerobatic manoeuvres, which caused the fuel level in the relatively low left tank to move away from the outlet.
- The pilot did not allow sufficient time for fuel flow to be restored from the alternative tank before adjusting the propeller pitch.
- The use of coarse pitch, while intended to reduce drag, likely prevented the engine from recovering power effectively at low RPM.
- The low altitude of the manoeuvres limited the pilot's options for troubleshooting and altitude recovery.