A helicopter engine fault was one factor behind the death of a Royal Navy serviceman during a training exercise, an investigation has concluded.
On 4 September 2024, three crew members were on board the Merlin Mk4, based at Royal Naval Air Station (RNAS) Yeovilton in Somerset, for night-flying exercises.
At about 20:50 GMT the aircraft ditched – a deliberate emergency landing on water, approximately 25 nautical miles south of Lyme Regis, Dorset.
A service inquiry found the right-hand seat pilot, Lt Rhodri Leyshon, had been “seriously injured” during the impact.
It also said he was “unable to escape from the aircraft as it entered the water”.
The inquiry found the helicopter crashed after a diaphragm inside the engine split.
“This allowed fuel to flow through the diaphragm and into the engine,” the inquiry report said.
“The excess fuel caused the engine to operate at a much faster speed than normal.”
It said the crew members then “erroneously concluded that the number one and three engines had failed”.
The report said these two engines were manually switched off, causing the remaining engine to reach its “overspeed trip threshold” and also deactivate.
“The loss of power from all three engines caused the aircraft to descend into the sea,” it said.