What happened
On 12 February 2001, a Jet Provost T MK5A, registration G-BYED, departed Londonderry airport for a short local visual flight rules (VFR) mission toward the southwest. The weather conditions at the time were favorable, characterized by good visibility and scattered clouds at 3,000 feet.
Approximately five minutes into the flight, the pilot returned to the airfield to perform a right-hand landing circuit for Runway 26. During the turn onto the base leg, while the landing gear and flaps were extended and the engine was at idle power, the engine experienced a sudden rundown. The pilot immediately declared a mayday to the tower. Because the aircraft was not equipped with an active ejector seat, the pilot had to prepare for an emergency landing.
Finding no suitable runways or clear terrain, the pilot identified the mud flats of the Loch Foyle estuary as the only viable landing site. To facilitate the landing, the pilot retracted the landing gear. The aircraft touched down on the mud at an estimated speed of 80 to 90 knots. While the impact caused minor damage to the underside of the fuselage, the aircraft remained largely intact, though it suffered salt water contamination.
The investigation
The investigation focused on the cause of the engine power loss and the subsequent emergency procedures. Following the touchdown, the pilot shut down all aircraft systems and noted that the fuel gauges indicated approximately 800 lbs of fuel remained in the tanks. The pilot was able to evacuate the aircraft and was rescued shortly thereafter by an army helicopter.
Technical inquiries into the engine failure centered on the Rolls-Royce Viper 202 turbojet engine. Maintenance engineers suggested that the engine rundown was likely the result of a failure of the HP fuel pump drive shaft, a theory that required further component examination for definitive confirmation.