The Royal Navy’s Commando Merlin helicopters have reached full operating capability (FOC) following a major upgrade programme to enhance their amphibious strike role, according to a press release issued on 29 February 2025.

Under the £399 million Merlin Life Sustainment Programme (MLSP), 25 helicopters – 19 Mk3 and six Mk3a variants – were converted to Mk4/4a standard by Defence Equipment & Support (DE&S) and industry partner Leonardo. The upgrades enable the aircraft to operate globally from Royal Navy vessels, supporting 3 Commando Brigade Royal Marines in littoral strike missions.

Key modifications include a folding main rotor head and tail, allowing two helicopters to fit on a single carrier lift, and an advanced defensive aid suite to detect hostile laser-guided threats.

Captain Neil Mathieson RN, Merlin DT Team Leader at DE&S, stated: “The Mk4/Mk4a has been fully ‘ship optimised’ to operate efficiently from Royal Navy vessels. This includes significant changes such as a new avionics suite, aligned with the Mk2 cockpit, extending the platform’s service life to 2030.”

The helicopters, operated by the Commando Helicopter Force (CHF), are now cleared to deploy from aircraft carriers, Type 23 frigates, Type 45 destroyers, and Royal Fleet Auxiliary ships. The upgrades also introduced synthetic training systems at RNAS Yeovilton, featuring augmented reality simulators for pilots and rear crews.

Clive Scott, Senior Vice President of UK Business at Leonardo Helicopters, said: “Our Yeovil workforce is proud to deliver these upgrades, ensuring the UK’s operational independence. The AW101 remains a global benchmark, with exports to Japan, Italy, and Poland benefiting from continuous investment.”

The MLSP retrofits improve interoperability across Merlin variants, streamlining supply chains and maintenance. The CHF’s roles include search-and-rescue, counter-narcotics, and disaster relief, alongside supporting the Carrier Strike Group.

George Allison
George has a degree in Cyber Security from Glasgow Caledonian University and has a keen interest in naval and cyber security matters and has appeared on national radio and television to discuss current events. George is on Twitter at @geoallison

34 COMMENTS

  1. “according to a press release issued on 29 February 2025”

    George: futurology?

    Or is time flying faster than I realised?

  2. Good news about the Merlins. I assume that’s relevant for the CSG 25. However, I wonder how the Wildcat upgrades are doing? Do all the Navy Wildcats have working tactical data links yet? And what about the Army Wildcat radars?

  3. Keeping Merlin going is important because I don’t think we will ever see a true Puma replacement. So that will leave Chinook, Wildcat, and Merlin to do the transport work.

    • I agree, great capability in Merlin.
      I have to admit, I’m left wondering on the medium lift subject. It appears to me that we’ve functionally been without a meaningful medium lift capability for quite some time now, even before getting rid of Puma. If that is the case, and our airmobile forces are basically making do with Chinook and Army Wildcat (presumably), what is this competition to fulfil? We’re not getting anywhere near enough to be able to do what the US does with their airmobile forces. If it’s just to avoid the embarrassment that we don’t have a proper medium lift helicopter, then I’m not sure it’s worth it.
      Don’t get me wrong, I think they’re a capability we should have, but they need to be a usable capability, not just a ticked box.

  4. In her UK growth speech yesterday Rachel Reeves mentioned Airbus and investment in Flintshire. Puma replacement at Broughton?

  5. Just a supplementary question: In my RN Sea King days I remember several very badly smashed up cabs being brought back to service by the factory at Yeovil. I know the Merlin is a totally different animal and only the tail cone is aluminium alloy with the main body made of Mineral Fibre (composite) but was it ever remotely possible that the Junglie Mk4 that ditched from PWLS last year could be rebuilt? With this government a replacement would be unthinkable but a total Junglie force of just 24 cabs is woefully inadequate.

    • There were no ‘rebuilds’ during MLSP. Mk3/3A came in the door, Mk4/4A went out the other end. CHF only had 24 Mk4 Sea Kings (848, 845, 846). The SK Mk4 was a much less complicated beast, hence the better serviceability rate.

  6. I know there were no rebuilds during the MLSP but my question was did they recover the ditched Mk4 and was the condition suitable for a possible rebuild at Leonardo?

    • Ah-Gotcha; they did and it was trashed. Tail off, cockpit away from rear fuse etc. (Which raises the Q, How hard did it hit the water if it was a ‘ditching’)

  7. I guess if the MoD were really serious about restoring the Commando fleet to 25 they might possibly consider taking the most intact ‘orphan’ Mk1 airframe from storage (assuming we’ve still got them?). Heavily cannibalised and totally different tail arrangement and avionics suite but if they threw money at it could it be possible?

      • No. Seagull is referring to the lost Merlin that ditched the other month and using one of the 11 Merlin HM1 ( not Commando types but ASW ) that were not upgraded to HM2 standard.
        Bought 44. Lost 3. Upgraded 30. 11 spares HM1.

        For years some, including me, speculated whether using them as dedicated Crowsnest cabs was feasible. According to more knowledgeable posters than me, they have been cannibalized so badly as to be unusable, or are now instructor, training frames at Sultan, Lyneham, or wherever.
        The NMH project has no bearing here, and regards Puma in the RAF SHF, not the FAAs CHF, in which the “Commando” Merlins reside.
        24 remain, ex RAF assets involved in Gordon Browns defence cuts. They originally totalled 22, then 6 Danish ones were diverted to the RAF disc to lack of heli assets in Helmand. That brought the fleet to 28, 25 of which went to the FAA.

  8. When are they ever serious?! I believe they’re too far gone and assume a singleton conversion would cost to much to be worth it.

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