AW101 / EH101 Merlin

The EH101, developed jointly by Agusta of Italy and GKN Westland Helicopters prior to their merger, combines military and civil variants in a single integrated program with an optional rear loading ramp and full ice protection system. The EH101 was in full production in both Italy and the United Kingdom with launch orders for over 80 aircraft. The EH101 was said by the manufacturer to have been the only new medium lift helicopter that is in full production and available in four variants.

The AW101, as it is now known, is the medium/heavy multi-role platform of choice in its class with extensive operational experience gathered in both the Land and Maritime environments. It benefits from a modern design with embedded safety-enhancing features. Based on a common airframe and core system, it is configured to meet diverse roles for pre-dominantly Maritime and Utility tasks. The large cabin can carry up to 38 troops on crashworthy seats or 16 stretcher patients. Three GE CT7-8E engines, with a two engine cruise option to extend range or endurance, provide unparalleled performance in all environments. Agility, range, and endurance coupled with a comprehensive advanced avionics and mission system suite enable the aircraft to fulfil multiple tasks in one mission. Roles include troop transport, casualty evacuation, tactical and amphibious support, combat SAR, disaster relief, anti-submarine and anti-surface warfare, airborne mine countermeasures, long range search and rescue (SAR), maritime interdiction and airborne surveillance and area control (ASAC). The Integrated Development Programme (IDP) under which the EH101 was developed was an Anglo-Italian collaborative program. Each nation was procuring variants of the baseline helicopter. Maritime patrol variants of the aircraft had been ordered by the British Royal Navy and by the Italian Marina Militare Italiana (MMI). The MMI also ordered the utility transport and enhanced air and surface surveillance variants and the British Royal Air Force had contracted for 22 EH101 SH (support helicopter) military utility aircraft.

In 1991 the United Kingdom selected IBM-Aerospace Systems Integration Corporation (ASIC) (subsequently Loral-ASIC, now Lockheed Martin ASIC (LMA)) as prime contractor to complete Royal Navy development, integration of the Mission System and production of 44 aircraft. Since then progress had been made on the programme through the award of the Collaborative Production Investment contract in March 1992 to EH Industries.

The Staff Requirement for the Medium Support Helicopter (MSH) was approved in March 1994. A submission to the Equipment Approvals Committee (EAC) was approved in February 1995 followed one month later by an announcement from the Secretary of State that 22 EH101 Support Helicopters would be procured, together with a smaller number of Chinooks, to meet the MSH requirement. The SH(EH101) contract was awarded in June 1995.

Awards were also made to Lockheed Martin ASIC for the Merlin Training System in July 1994, and the MERLIN Support and Spares Availability System (MSSAS) in July 1996.

Progress on the project was hampered by accidents on the collaborative program to three prototype aircraft in 1993, 1995 and 1996. However, the first flight by a production Merlin was on 6 December 1995 and the first mission system fitted Merlin flew in January 1997. Royal Navy Intensive Flight Trials began on schedule in December 1998.

The aircraft had a then state-of-the-art, integrated mission system, which processes data from an extensive array of on-board sensors, giving Merlin an independent capability to search for, locate and attack submarine targets. It is this autonomous capability that made Merlin unique among existing ASW helicopters. The aircraft and its mission system are managed by two computer systems, linked by dual data buses. The cockpit is designed for operation by a single pilot, with the auto-pilot allowing for hands-off flight for most of the mission.

Normally flown by a crew of three, pilot, observer and aircrewman, Merlin was equipped with the Thomson-Marconi active "dunking" sonar, giving enhanced submarine detection ranges, and the GEC Marconi AQS 903 acoustic processor. All crew stations could access the management computers and operate the tactical displays. These were fed by the Marconi Blue Kestrel radar which possesses full 360-degree coverage and an ability to Track-While-Scan surface contacts. It could also pass tactical information via a datalink to other participating units; a significant capability which has not been utilised by maritime helicopters before.

Merlin was designed to operate in all weathers from the flight decks of both large and small ships (Invincible class aircraft carriers and Type 23 frigates). It is powered by three Rolls Royce RTM 322 engines, is capable of speeds of up to 150 knots and has a range of 200 nautical miles. It can carry up to four homing torpedoes or depth charges, for use against threat submarines and can provide targeting information via datalink for the prosecution of surface threats. The Merlin retained all the secondary role capability of its predecessor, the Sea King, including loadlifting, casualty evacuation, troop carrying and Search and Rescue.

SH(EH101), designated the Merlin HC Mk 3, filled a capability gap between Chinook and Puma. It also replaced the obsolete Wessex. Based on the military utility version of the Anglo-Italian EH101, it was designed to operate by day and night, in hot and high or cold and icing conditions undertaking a wide variety of roles including troop carrying, small vehicle and/or cargo carrying capability. It would support ground forces in a wide range of operational scenarios, including combat search and rescue, in National, NATO and UN operations. A range of role-fit and portable support equipment was also available to further tailor the aircraft for special operations.

The Merlin HC Mk 3 was a significant advance on the aged Wessex helicopter and also reflected the progress in both roles and capabilities of support helicopters. The Merlin HC Mk 3 has a single main rotor configuration powered by three uprated Rolls Royce Turbomeca RTM322 engines. It has an all-up take off mass of 14.6 tonnes, maximum speed of 167 knots and range on internal fuel in excess of 1000km. The operating range can be extended by virtue of an air to air refuelling capability and continuous operations are possible. Designed to carry 24 troops in crash-attenuating seating, fitted with active noise reduction (ANR) headphones. The seats can be folded away and a range of cargo or small vehicles loaded via a rear ramp or side door. A cargo winch and roller conveyor for palletised freight are integrated. Under slung loads can be carried.

The aircraft incorporated the then latest technology in composite structures, multiple system redundancy and enhanced health and useage monitoring to minimise life cycle costs (LCC). Active control of structural response (ACSR) struts reduce vibration at all speeds. It was designed to be highly reliable, maintainable and supportable away from its normal operating bases.

Pilot workload is eased with automated flight control and aircraft management, integrated GPS/INS based navigation, extensive communication systems and Night Vision Goggle (NVG) compatible electronic instruments and displays. All the aircraft would be fitted with a comprehensive Defensive Aids Suite (DAS) that will include a Radar Warning Receiver (RWR), a Laser Warning Receiver (LWR), Chaff and Flare dispensers and a Directional Infra-Red Countermeasures (DIRCM) system. A limited number would also be fitted with Forward Looking Infra-Red (FLIR). 3G agility and a low noise signature enhance effectiveness and minimise environmental impact. Wire strike protection, armoured crash attenuating crew seats, automatic fire protection systems and the defensive aids provide enhanced survivability.

Merlin HM MK1 (formerly Merlin EH101) was an Anti-Submarine (ASW) variant of the EH101 helicopter. It entered service in December 1998, replacing the ageing ASW Sea King (Mk 6). The collaborative program began in 1979 through EH Industries, the company formed by Agusta of Italy and GKN Westland in the UK. Designed in Western Europe, it was the largest collaborative helicopter project in history and the most powerful helicopter in terms of military capability. The mission system was world-leading and the weapons system was a significant force multiplier compared with existing capability.

By mid-2003 the EH-101 was in service with the UK Royal Air Force and the Royal Navy, the Italian Navy and Canadian Forces, and had accumulated 36,000 flying hours. By the end of 2003 ninety-two EH-101 helicopters were in use world wide. By mid-2004 the fleet had nearly 50,000 hours of flight operations.