What happened
A cargo flight departing from RAF Abingdon for RAF Akrotiri encountered significant mechanical issues during its initial climb. The aircraft was transporting a relief crew, eight police dog handlers, and eight dogs. During the ascent, a fuel leak was detected in the first engine, prompting the crew to shut down that engine and feather the propeller. Following this action, the flight crew declared an emergency and requested a blind approach back to RAF Abrondon.
Shortly after, instruments indicated a significant loss of fuel from the second tank on the port wing. Although the crew attempted to mitigate the leak by deactivating fuel cocks and boosters for that specific tank, the aircraft's performance degraded further. As the Avro Beverley transitioned to its final approach, the second engine on the port wing failed to respond to power increases. This loss of power caused the aircraft to lose altitude and airspeed.
Unable to reach the runway, the pilot attempted an emergency landing in a nearby field. During this maneuver, the aircraft struck high-tension cables and several elm trees, which severed the port wing from the fuselage. The impact destroyed a caravan and a prefabricated structure before the aircraft overturned. The accident resulted in 18 fatalities among the occupants, including three crew members, and 2 fatalities on the ground.
Findings
A Board of Inquiry determined that the crash was caused by the simultaneous loss of power from both engines located on the port wing. Investigations revealed that a non-return valve between the first port fuel tank and the collector box had been installed in reverse. This error, combined with the fact that the fuel supply from two additional port-side tanks had been switched off, led to engine starvation. While the first engine was shut down manually due to a leak, the second engine failed because of the incorrectly installed non-return valve and the isolation of necessary fuel sources.