What happened
On 13 July 2008, a North American P-51D-20 Mustang, registration G-BIXL, was participating in an air show at Duxford Airfield, Cambridgesle. Following a series of formation flights, the aircraft broke away from the display to enter the circuit. While on final approach to a grass runway, the engine began to run with slight roughness. In an attempt to maintain altitude, the pilot advanced the throttle, which resulted in a significant loss of power accompanied by puffs of white and dark smoke from the engine.
As the aircraft descended, the pilot adjusted the flaps and switched fuel tanks, but the power loss persisted. Realising the aircraft would likely not reach the intended runway, the pilot opted to land on a parallel grass runway. During the approach, the aircraft crossed the edge of a raised taxiway, which caused the aircraft to be thrown back into the air with a high nose attitude.
Upon the second touchdown, the aircraft landed on the right main wheel first. The left main gear subsequently dug into the ground, causing the axle mounting casting to bend and the aircraft to yaw left. The pilot applied right rudder and braking to maintain control, but the aircraft began to skid. During the deceleration, the tail rose, causing the propeller to strike the ground before the aircraft came to a halt.
The investigation
The AAIB examined the aircraft's engineering history, noting that the engine had been recently rebuilt and the propeller overhauled. Ground runs and flight tests conducted on the day of the accident, as well as during previous sorties, had shown no engine problems. Investigation of the fuel system revealed that the booster pump pressure was normal and sufficient fuel was present in the tanks, though some fuel was found in the filler cap rims. The engine was manually turned and showed good compression with no irregular noises.
Findings
- The aircraft sustained damage to the left landing gear axle, leg, and tyre, and the propeller struck the ground.
- The exact cause of the engine's rough running and subsequent power loss could not be positively determined.
- It is possible that engine handling techniques required for close formation flying may have triggered the intermittent engine fault.