Investigation Summary
The accident flight began at 13:32 UTC. Shortly after takeoff, the crew experienced significant vibrations which they attributed to the engines. The AAIB later identified that the Air Cycle Machine (ACM) had suffered a bearing failure, which can produce vibrations and noise easily mistaken for engine distress. In the process of managing the perceived emergency, both engines were shut down. A critical finding in the wreckage was a missing rivet head on the left engine fuel shut-off lever, which may have allowed the lever to move to the 'off' position inadvertently or made it difficult for the pilot to distinguish between throttle and fuel cut-off movements under stress. Approximately 70 seconds before impact, the aircraft was in a dual-engine flameout condition. The crew attempted a relight of both engines. However, they likely initiated the restart of the second engine before the first had reached idle speed. This simultaneous restart attempt drew significant energy and time, preventing either engine from reaching a thrust level sufficient to arrest the aircraft's descent. The aircraft struck the side of a house in Romsey Close and was consumed by an intense post-crash fire. The investigation was hampered by the lack of a Flight Data Recorder (FDR) or Cockpit Voice Recorder (CVR), which were not required for this Cessna 500 Citation I at the time.
Final Conclusions
The AAIB concluded that the accident resulted from a combination of a misleading mechanical failure (ACM vibration) and subsequent crew actions that led to a dual engine shutdown. Contributory factors included a mechanical defect in the throttle quadrant (missing rivet) and a flawed restart technique where the crew attempted to relight both engines at once rather than focusing on one. The final report (AAR 3/2010) was published on 21 May 2010.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Pilot A
First Officer
Pilot B
Systems & Failure Modes
Air Cycle Machine (ACM)
Part of the environmental control system; a bearing failure in this unit caused the vibrations that the crew misidentified as an engine problem.
Throttle Quadrant
The assembly containing the throttle and fuel shut-off levers. A missing rivet on the left lever likely compromised the mechanical integrity and tactile feedback of the fuel cutoff system.
Interesting Facts
- 01The aircraft was not equipped with a Flight Data Recorder or a Cockpit Voice Recorder.
- 02Both engines were found to be operating at the moment of impact, but had not reached sufficient thrust to maintain flight.
- 03The vibration reported by the pilots was likely caused by a mechanical failure in the air cycle machine (ACM).
- 04A rivet head was missing from the left engine fuel shut-off lever, potentially leading to an inadvertent engine shutdown.
- 05The passengers included prominent British racing figures David Leslie and Richard Lloyd.
Safety Actions & Advisories
Throttle Quadrant Inspection
The FAA was recommended to require Cessna to introduce scheduled inspections of the Citation 500 throttle quadrant to ensure the integrity of riveted joints on fuel shut-off levers.
Emergency Restart Checklist Amendment
The FAA was recommended to require Cessna to amend the 'EMERGENCY RESTART – TWO ENGINE' checklist to emphasize restarting only one engine at a time.
Flight Recorder Requirements
ICAO was recommended to adopt requirements for flight recorders on turbine-powered aircraft with a maximum takeoff mass of 5,700 kg or less.