What happened
On 25 December 2001, an Agusta A109E, registration G-DPPH, was performing a passenger transport flight from Morriston Hospital to an operator base near Carmarmen. The flight involved the pilot and two passengers. The aircraft was operating with a known defect in the left forward fuel tank's electric booster pump, which had been identified during a flight two days prior. To facilitate a scheduled pump replacement, the aircraft was flying with a reduced fuel load.
While transiting through heavy snow showers, the aircraft's second fuel pump also failed. This triggered a double engine failure as the engines ran out of usable fuel. The pilot attempted to maintain rotor RPM by lowering the collective and initiated an emergency landing in a field near Cross Hands. The helicopter struck the ground heavily, resulting in severe damage to the landing gear, tail cone, and both the main and tail rotor blades. Despite the impact, there were no fatalities, and the two minor injuries sustained by the crew and a passenger were not serious.
The investigation
The investigation focused on why the aircraft suffered a total loss of power despite having fuel remaining in the tanks. Investigators examined the aircraft's fuel system, which relies on electric booster pumps to maintain pressure, though engine-driven pumps can draw fuel via suction.
It was established that because the cross-feed valve was in the 'NORMAL' position, the failure of the first pump had caused the valve to open automatically. This configuration allowed the remaining functional pump to pressurize the cross-feed line, which inadvertently prevented the engine-driven pump from effectively drawing fuel from the left tank via suction. The investigation also scrutinized the operator's Minimum Equipment List (MEL) and the emergency checklists used by the pilot.