It has been a long time coming. The process of introducing the Merlin HM Mk1 shipborne helicopter to UK Royal Navy service finally began on 1 December, 1998, with the commissioning of 700M Naval Air Squadron (NAS) at RNAS Culdrose in south-west England. In its role as Intensive Flying Trials Unit (IFTU), 700M NAS will, over the next two-and-a-half years, develop the aircraft into a front-line weapon system, paving the way for the deployment of the first operational squadron at sea in late 2001.

In parallel with the IFTU activity, a programme of aircraft development, qualification and production continues under the stewardship of prime contractor Lockheed Martin ASIC, the Ministry of Defence (MoD) and the RN. Although the aircraft's official in-service date (ISD) is March - when the MoD Procurement Executive accepts the 12th of 44 Merlin HM Mk1s on order - work to complete mission system integration and flight clearance will continue into 2001.

Conceived to meet Staff Requirement (Sea) 6646 for an anti-submarine warfare (ASW) Sea King Replacement (SKR), the Merlin is emerging from a difficult infancy. Born out of the Anglo-Italian EH101 helicopter International Development Programme (IDP), its development has been hampered by technical difficulties (exacerbated by the loss of three EH101 pre-production airframes in separate crashes) and project management failings in the programme's formative years.

The original endorsement for SKR development in 1982 envisaged a phased procurement route, with EH Industries - the industrial joint venture between Agusta and GKN Westland - taking the role of main contractor to develop the EH101 naval variants for the RN and the Italian navy. But spiralling costs and six years of accrued delays to the aircraft's ISD forced the MoD to revise its procurement strategy.

Problems stemmed from difficulties indeveloping a fully capable mission system specific to the RN's needs - in the absence of a single system integrator. "The integration task was underestimated," says Air Cdre Barry Thornton, director of maritime projects within the MoD Procurement Executive Directorate General Air Systems 2. "In retrospect, a major misjudgement was not to have all project management controlled by one prime contractor."

In 1990, it was decided that the project required a prime contractor to take overall responsibility for development specific to the RN variant, mission system integration, and aircraft production and delivery. Following competition, IBM ASIC (now Lockheed Martin ASIC) was awarded a £1.5 billion prime contract in October 1991 to supply 44 aircraft with integrated and fully functional mission systems. Separate contracts were later signed with Lockheed Martin ASIC for an integrated training system and in-service support infrastructure.


Since the prime contract award, the Merlin's progress has improved. "The programme [to ISD] has slipped by only three months," says Thornton, despite the complex and challenging nature of the programme and the accidents to the development aircraft, which caused serious disruption.

It is an uncomfortable fact that the Merlin's protracted gestation has seen the demise of the very threat that underpinned its procurement in the first place. The SKR requirement was predicated around the detection and, if necessary, prosecution of Soviet nuclear submarines in the eastern Atlantic theatre.

To maximise its potential in that Cold War scenario, the Merlin was designed to operate from the then-new Type 23 ASW frigate, exploiting the ship's long-range Sonar 2031Z very low frequency passive towed-array sonar. This, in turn, drove exacting agility requirements for small ship operation (launch and recovery in conditions up to Sea State 6, in 50kt (90km/h) of wind, at night or in poor visibility) in the harsh Atlantic operating environment. At the same time, primary and secondary mission profiles dictated that the SKR would necessarily be a large helicopter if it were to achieve its intended endurance at long range with a full ASW suite and weapon load.

Today, however, hunting nuclear-powered submarines in vast expanses of ocean is no longer the RN's prime task. Last year's Strategic Defence Review (SDR) affirmed the service's new role as a maritime component of joint force projection and put paid to a purchase of a planned second batch of up to 22 Merlin HM Mk1s because of the reduced submarine threat.

So is this destined to be a "Cold War" ASW helicopter overtaken by events? The RN thinks not. Although the second production batch has been axed (much to the operator community's regret), the service remains convinced that the quantum leap in capability offered by the Merlin will be just as relevant to its new concept of operations.

"The SDR put a premium on joint expeditionary forces, notably the power projection capabilities of aircraft carriers," says Cdre Tony Hogg, commanding officer of RNAS Culdrose. "The Merlin will bring a quantum increase in the ability to defend carriers against submarine and surface threats. It will also be able to take part in peace support and humanitarian operations."

In its ASW primary role, the Merlin is being groomed as part of a new anti-submarine force designed to counter the emerging threat from regional navies operating quiet diesel-electric submarines in the littoral. This new arena - outside NATO's traditional sphere - is likely to be characterised by warm and relatively shallow waters, a mix noted for its poor acoustics.

In this context, the Merlin will be employed on screening and long-range precursor operations using its own suite of advanced active and passive sonics. The low-frequency active dipping sonar, supplied by Thomson Marconi Sonar (TMS), combines the FLASH expandable array with the AQS-950 acoustic processor, while sonobuoy processing (LOFAR, DIFAR, VLAD, BARRA, DICAS and CAMBS) is performed by the same company's AQS-903 acoustic processor. A weapon load of up to four Sting Ray torpedoes or Mk11 Mod 3 depth charges can be carried.

The RN says the Merlin's autonomy and mobility will benefit further from a new sensor synergy with the Type 23 frigate, a combination designed to give the task group an organic localisation and attack capability. Type 23s will receive the new Sonar 2087 low-frequency active/passive sonar (LFAS) system from 2003, allowing ships to maintain outer-zone surveillance over a relatively large area for extended periods, using an embarked Merlin to investigate and, if necessary, attack contacts. The Sonar 2087 and the Merlin are also seen to have an important inner-zone role, the combination of LFAS detection ranges and airborne mobility being needed to cover a greater perimeter than is currently possible.


There is also a move to exploit the Merlin in a long-range search and destroy role, operating autonomously rather like a maritime patrol aircraft (MPA). This role would lend itself to area operations, clearing an operating area for theatre entry, complementing MPAs at the edge of the operating area, or acting independently ahead of a force in transit.

In its other primary role, the Merlin will offer a major anti-surface warfare (ASuW) capability through its surface surveillance and over-the-horizon targeting capabilities. Prime above-water sensors are the Marconi Avionics Blue Kestrel 5000 multi-mode radar and the Racal Orange reaper electronic support measures outfit.

Because the Merlin will not be equipped (initially, at least) with an anti-ship weapon, co-operation with the Lynx HMA Mk8 will be particularly important in ASuW tasks. Operating the two aircraft together will allow full advantage to be taken of the Lynx's Sea Owl passive identification device and Sea Skua anti-ship missiles. The Merlin will also be the first RN helicopter to have a datalink, enabling it to transmit and receive ASW and ASuW tactical picture information while operating in a hostile RF environment and under a restrictive communications policy. Ultra Electronics is supplying the Link 11 datalink processor and data terminal set.

Development and qualification of the Merlin is continuing in parallel with airframe production. RN01, the first of the 10 HM Mk1 aircraft so far delivered from GKN Westland's Yeovil production line, is assigned to the IDP for flight performance testing set to run until late 1999.

RN02 and RN03 are being used by Lockheed Martin ASIC for operational performance acceptance procedure (OPAP) trials to test the aircraft against performance and mission specifications. The first phase was completed at Aberporth late last year, and next month the programme will undertake a first phase of proving trials at the fully instrumented Atlantic Underwater Test and Evaluation Centre (AUTEC) in the Bahamas.

Later OPAP tests will be conducted in the Hebrides and back at AUTEC. A final OPAP report is expected in the third quarter of 2000.

The results of the trials will decide final corrections and revisions to the Merlin's mission computer software. The latest point release, Tactical Management Function (TMF) 4.5, is close to full functionality, but Lockheed Martin ASIC intends a final TMF iteration to be issued in late 1999. This top-off release will correct deficiencies identified during OPAP, plus any other software revisions that may arise following engineering changes during development.

RN09 is being used by Lockheed Martin ASIC and the DTEO for EMC and Tempest testing. RN10 is undertaking a six-week programme of production equivalency qualification to verify the capture of all pre-production features in the production-standard aircraft

It falls to the IFTU to pave the way for the Merlin's introduction to front-line service, says 700M NAS commanding officer Lt Cdr Phil Shaw. "The purpose of the IFTU is to bring together all items to produce a fighting machine and build a training system. This will involve introducing procedures and developing tactics for the full range of aircraft roles. We have two-and-a-half years to get the aircraft and trained people ready for the first front-line squadron."

The IFTU has received two aircraft (RN05 and RN06) out of its planned complement of four. It will reach full strength in early 1999 with the arrival of RN07 and RN08, previously used for pilot training at Yeovil.

IFTU activities will include flying operations from all RN ships slated to receive the Merlin, including Invincible-class carriers and Type 23 frigates. Another important task will be to validate assumptions on the RN's requirement for single-pilot operation.

Behind all these activities, the Defence Test & Evaluation Organisation (DTEO) at Boscombe Down is carrying out a phased programme of military aircraft release (MAR). Airworthiness trials to support MAR began in April 1998 using RN04.

RN10 is planned to join the MAR flight programme towards the end of the first quarter of the year. It is provisionally intended to instrument RN12 to undertake ship/helicopter operating limit trials in support of MAR.

Initial MAR was issued in November 1998, clearing the way for IFTU flying to start. Five phased MAR iterations will follow at roughly six-monthly intervals, each reflecting the progressive expansion of the aircraft envelope and a new standard of mission system functionality. This process will culminate in a final MAR release in 2001 prior to the Merlin's first front-line deployment.


As the qualification and system optimisation process continues, a programme of retrofits will ensure that all aircraft meet the build standard. The backfitting schedule will be determined on an aircraft-by-aircraft basis, according to programming and maintenance slots, with work being done at Yeovil and Culdrose.

Work is continuing to hone the new Merlin Training System (MTS), with Lockheed Martin ASIC now conducting curriculum walkthrough at the so-called Merlin University at the Culdrose base. The programme involves trainers, simulators, training facilities and curriculum for all flying crew (pilots, observers and aircrew), ground crew and maintainers.

Some problems have been encountered in the MTS, specifically the integration of new aircrew simulators supplied by CAE Electronics. This has meant providing aircrew training at Yeovil in advance of the simulator suite becoming operational at Culdrose in late 1999.

The RN's next major goal is the commissioning of the first front-line Merlin squadron - 814 NAS - in early 2001. This ties in with the return to operational service in late 2001 of HMS Ark Royal after a major two-year refit. It will be the first carrier fully fitted to support and operate the Merlin. Squadron 814 will be followed by two other front-line Merlin squadrons: 829 NAS will be parent to small ships' flights assigned to Type 23 frigates, and 820 NAS will form a second carrier squadron.

Source: Flight International