What happened
On 30 March 2008, a Cessna Citation 500, registration VP-BGE, departed Biggin Hill Airport on a private flight destined for Pau, France. Shortly after takeoff, the flightcrew reported experiencing engine vibration and decided to return to the departure airfield.
During the downwind leg for Runway 2/21, the aircraft began to descend. The crew reported a significant loss of power just moments before the aircraft struck the side of a residential building. The impact resulted in an intense fire, and there were five fatalities among the two crew members and three passengers.
The investigation
The AAIB investigation examined the mechanical condition of the aircraft, the engine performance, and the flight crew's actions during the emergency. Investigators analyzed the wreckage, including the engine controls and fuel systems, and conducted various engine test cell runs using a Pratt & Whitney JT15D-1A engine.
Testing focused on engine relight capabilities at different speeds and the impact of fuel valve positions. The investigation also included computer-based simulations and flight performance calculations to determine if the aircraft could have recovered its altitude if the engines had been successfully relit in a timely manner.
Findings
- A mechanical failure within the air cycle machine likely triggered the initial vibration that prompted the return to Biggin Hill.
- A missing rivet head on the left engine fuel shut-off lever may have caused the inadvertent shutdown of the left engine.
- Approximately 70 seconds before the impact, neither engine was producing thrust.
- The crew likely attempted to relight the second engine before the first engine had reached a stable idle speed, leaving insufficient time to develop the thrust required to stop the descent.