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AgustaWestland AW101

The AgustaWestland AW101 is a medium-lift helicopter in military and civil use.

First flown in 1987, it was developed by a joint venture between Westland Helicopters in the United Kingdom and Agusta in Italy in response to national requirements for a modern naval utility helicopter.

Several operators, including the armed forces of Britain, Denmark, and Portugal, use the name Merlin for their AW101 aircraft.

It is manufactured at factories in Yeovil, England, and Vergiate, Italy.

Licensed assembly work has also taken place in Japan and the United States.

Prior to 2007, the aircraft had been marketed under the designation EH101.

The original designation was EHI 01, from the name given to the Anglo-Italian joint venture, European Helicopter Industries, but a transcription error changed this to EH101.

In 2000, Westland Helicopters and Agusta merged to form AgustaWestland, leading to the type’s current designation.

The AW101 entered into service in 1999 and has since replaced several older helicopter types, such as the Sikorsky SH-3 Sea King, performing roles such as medium-sized transport, anti-submarine warfare, search and rescue, and ship-based utility operations.

The Royal Canadian Air Force (RCAF) operates the CH-149 Cormorant variant for air-sea rescue.

Another variant, the Lockheed Martin VH-71 Kestrel, was produced to serve in the United States presidential transport fleet before the program was cancelled and the aircraft sold off to Canada for parts.

Civil operators use the AW101 for passenger and VIP transportation.

The type has been deployed to active combat theatres, such as in support of coalition forces during the Iraq War and the War in Afghanistan.

The AW101 Merlin follows a conventional design layout, but makes use of advanced technologies, such as the design of the rotor blades, avionics systems, and extensive use of composite materials.

The fuselage structure is modular and comprises an aluminium–lithium alloy, designed to be both light and damage-resistant.

The AW101 is designed for operating in extreme weather conditions; it is fitted with a de-icing system and rated to operate in temperatures ranging between −45 and +50 °C.

The aircraft’s control systems allow the AW101 to maintain a stable hover in 74 km/h (40 kn) crosswinds.

An active vibration control system, known as the active control of structural response system, reduces airframe vibration by up to 80%, increasing crew comfort and minimising buildup of stress on the airframe.

The cockpit is fitted with armoured seats for the crew, and can withstand an impact velocity of over 10 m/s.

Dual flight controls are provided, though the AW101 can be flown by a single person.

The pilots’ instrument displays include six full-colour high-definition screens and an optional mission display; a digital map or forward looking infrared (FLIR) display can also be installed.




Westland-built basic air vehicle prototype, first flown 9 October 1987.


Agusta-built Italian basic air vehicle prototype first flown on 26 November 1987 and used for deck trials but was destroyed on 21 January 1993 following a rotor brake malfunction.


Westland-built and the first civil configured Heliliner, used for engine vibration tests and icing trials in Canada.


Westland-built British naval prototype, lost in an accident on 7 April 1995 after a drive train control rod failure.


Westland-built Merlin development aircraft eventually equipped with Merlin avionics.


Agusta-built development aircraft for Italian Navy variant first flown 26 April 1989.


Agusta-built military utility aircraft with rear-loading ramp.


Westland-built civil prototype.


Agusta-built military utility prototype with rear-loading ramp.

Model 110

Italian Navy ASW / ASuW variant, eight built.

Powered by T-700-GE-T6A1 engines.

Fitted with Eliradar APS-784 radar and Honeywell HELRAS dipping sonar.

Armed with torpedoes or Marte anti-ship missiles.

Model 111

Royal Navy ASW/ASuW variant, designated Merlin HM1 by customer.

Powered by RTM322 engines and fitted with Blue Kestrel radar, Thomson Marconi FLASH dipping sonar and Orange Reaper ESM. 44 built.

Model 112

Italian Navy early warning variant with same airframe as Model 110 but with Eliradar HEW-784 radar in large under fuselage radome.

Four built.

Series 200

Proposed military utility version with no rear-loading ramp.

Series 300 Heliliner

Proposed civil transport with no ramp.

In 2000, British International Helicopters conducted service trials using PP8; these did not lead to a commercial service.

Series 310

Proposed version of Heliliner with full airline avionics for operation from oil platforms. No production.

Model 410

Italian Navy transport variant with folding rotors and tail boom.

Four built.

Model 411

Royal Air Force transport variant, designated Merlin HC3 by customer, 22 built.

Model 413

Italian Navy special forces and amphibious assault transport with more advanced avionics.

Model 500

Proposed civil utility variant with rear-ramp.

Model 510

Civil utility variant with rear ramp, two built. One used for Tokyo Metropolitan Police Agency, and one used to support US101 bid.

Model 511

Canadian military search and rescue variant, designated CH-149 Cormorant by customer.

Model 512

Merlin Joint Supporter for Royal Danish Air Force.

Eight acquired for search and rescue (512 SAR) and six for tactical troop transport (512 TTT).

The six transports were sold to RAF (as Merlin HC3As) and replaced by six new-build Merlins.

Model 514

Portuguese Air Force search and rescue variant, six built.

Model 515

Portuguese Air Force fisheries protection variant, two built.

Model 516

Portuguese Air Force combat search and rescue variant, four built.

Model 518

Japanese Maritime Self-Defence Force mine countermeasures and transport variant, two built.

Model 519

Presidential Transport variant for the United States Marine Corps as the VH-71 Kestrel, four test vehicles and five pilot production aircraft built.

Model 610

Algerian Naval variant.

6 delivered.

Model 611

Italian Air Force Combat Search and Rescue variant, powered by CT7-8E engines. 15 on order.

Model 612

(SAR Queen)

Norwegian search and rescue variant, operated by the Air Force.

16 ordered with option for 6 more.

Model 640

Saudi Arabian VVIP variant, operated by the Air Force.

2 delivered.

Model 641

Indian VVIP variant

Latter delivered to Nigerian and Azerbaijani Air Forces.

Model 642

Algerian VVIP variant, 2 delivered.

Model 643

Turkmenistan VVIP variant, operated by the Air Force.

2 delivered.

Merlin HM1

Royal Navy designation for the Model 111.

Merlin HM2

Avionics retrofit of 30 HM1s for the Royal Navy.

Merlin HC3

Royal Air Force designation for the Model 411.

Merlin HC3A

Royal Air Force designation for six former Royal Danish Air Force Model 512s modified to UK standards.

Merlin HC3i

Royal Navy will fit seven HC3 with folding rotor heads as an interim (3i) measure until the full HC4 upgrade is available.

Merlin HC4/4A

The conversion of 25 RAF HC3/3A (19 HC3 and 6 HC3A) for RN use in hand with the first flight taking place in November 2016.

HM2 cockpit, folding tail/blades and other adaptations for naval use.

CH-148 Petrel

Ship-based anti-submarine helicopter for Canada.

35 originally ordered by the Canadian Forces, reduced to 28 and cancelled in 1993.

CH-149 Chimo

Search and rescue helicopter for Canada.

15 ordered by the Canadian forces, but later cancelled.

CH-149 Cormorant

Search and rescue helicopter for Canada, 15 ordered and delivered.

Lockheed Martin VH-71 Kestrel

Cancelled USMC variant that was intended to serve as the US Presidential helicopter.


Italian Navy designation for the MP variant.


Italian Navy designation for the AEW variant.


Italian Navy designation for the Amphibious Support Helicopter (ASH) variant.


Italian Air Force designation for the CSAR variant.

Kawasaki Heavy Industries MCH-101

Japan Defence Agency designation of Model 518





26 troops

(38 passengers)


5 tonnes of payload


4 stretchers (with sonar array removed) for Merlin HM1

30 seated troops


45 standing fully equipped combat troops,


3,050 kg (6,724 lb) of internal payload, 5,520 kg (12,169 lb) of external payload,


 16 stretchers for AW101


19.53 m (64 ft 1 in) fuselage


6.62 m (21 ft 9 in)

Empty weight

10,500 kg (23,149 lb)

Max take-off weight

14,600 kg (32,187 lb)


3 × Rolls-Royce Turbomeca RTM322-01 turboshaft engines,

1,566 kW (2,100 hp) each (take-off power)

Main rotor diameter

18.59 m (61 ft 0 in)

Main rotor area

271.51 m2 (2,922.5 sq ft) 


RAE 9651 


RAE 9645/RAE 9634


Cruise speed

278 km/h (173 mph, 150 kn)

Never exceed speed

309 km/h (192 mph, 167 kn)


1,389 km (863 mi, 750 nmi) 


5 hours

Service ceiling

4,575 m (15,010 ft)



4 × Sting Ray homing torpedoes 


Mk 11 depth charges


Smiths Industries OMI 20 SEP dual-redundant digital automatic flight control system

Navigation systems

BAE Systems LINS 300 ring laser gyro, Litton Italia LISA-4000 strapdown attitude and heading reference system.


Selex Galileo Blue Kestrel 5000 maritime surveillance radar


Racal Orange Reaper ESM


Thomson Marconi Sonar AQS-903 acoustic processor

Active/passive sonobuoys

Thomson Sintra FLASH dipping sonar array.

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