The Royal Marines have reported the first flight of the latest version of the AW101 Merlin. The Merlin Mk4 is a version of the ex-RAF Mk3 specially designed for operations at sea. It will be the mainstay of the Commando Helicopter Force (CHF) – part of Britain’s tri-service Joint Helicopter Command – for the next decade and beyond.

The first Mk4 took to the air a few days ago, after technicians and engineers at Leonardo in Yeovil completed modification work to convert a battlefield Mk3 into a Mk4. The Merlin Mk3 is the version originally deployed by the RAF and progressively transferred to the Royal Navy since 2012. Command of the UK Merlin Mk3 fleet was formally transferred from the RAF to the Royal Navy in September 2014.

New features on the latest version include a folding main rotor head and folding tail, which make it much more suited to operating from RN carriers and assault ships at sea, and a new digital cockpit developed for the RN’s fleet of Merlin HM2 anti-submarine warfare helicopters.

The first Mk4 is likely to be ready for front-line operations by late 2017, with the entire fleet of 25 converted by the end of 2020. They will replace the CHF’s current Westland Sea King Mk4s.

At present the two troop-carrying squadrons of Commando Helicopter Force, based at RNAS Yeovilton – 845 and 846 NAS – operate the Mk3 and Mk3i (the latter has undergone enhancements and improvements which plug the gap between Nos.3 and 4).