The Airbus Helicopters EC155 B1 is a medium-weight multi-role utility twin engine helicopter accommodating up to 12 passengers and 2 crew. The EC155 B is a development of the AS365N Dauphin II, with 40% larger cabin area, a new five-bladed Spheriflex main rotor with an extremely low vibration level and 'glass cockpit'. The EC155 B1 is powered by a pair of Turbomeca Arrius 2C2 turbine engines. The new generation of Fenestron tail rotor takes part in the decrease in external noise level. This tail rotor has 10 blades spaced irregularly around the hub. Development of the EC-155, initially known as AS-365N-4 Dauphin started in September 1996. The development of the AS365 N4 wide body helicopter was announced at International Paris Airshow in June 1997. A mockup of the N4 was shown at the International Paris Air Show at Le Bourget and on 17 June 1997, the prototype EC155, F-WDFK, a rebuilt Dauphin, flew first at Marignane. The first pre-poduction EC155 B flew on 11 March 1998. The French Civil Aviation Authority (DGAC) and the German Government Agencies (LBA) certification was awarded in December 1998 and the EC 155 got its single-pilot IFR certificate on 25 January 2000. The first three Eurocopter EC 155 Bs were officially handed over to the German Federal Ministry of the Interior / Bundesgrenzschutz (BGS) at the Bonn-Hangelaar base of the BGS on 16 March 1999. The EC155 B1 is a development of the EC155 B with more powerful engines and improved performance at high altitude and in hot temperature conditions. Deliveries of the EC 155B1 version began in September 2002. More than 170 EC155s have been sold. Since March 2015, Airbus Helicopters uses 'H155' as marketing designation for the EC155 helicopters. In 2015, Airbus Helicopters and Korean Aerospace Industries (KAI) entered into an agreement to transfer the core production operations of EC-155 helicopters to South Korea. Korea Aerospace Industries (KAI) became the sole manufacturer of this type of helicopters. Now the entire development of the helicopter rested on the KAI company, which started the development of the helicopter into military versions. The LAH version was created armed with a 20 mm cannon, side mounts for missiles, bombs and machine guns. The helicopter can carry 10 armed soldiers on board. In 2023, Airbus Helicopters and local partner KAI launched series production of the Light Armed Helicopter (LAH) – derived from the former’s H155 medium-twin – with deliveries to commence in 2024.

As a result of the merger between the Eurocopter parents Aérospatiale-Matra; DaimlerChrysler Aerospace (DASA) and Construcciones Aeronàuticas Sociedad Anonima (CASA) in July 2000, the Eurocopter group became a division of the new formed EADS (European Aeronautic Defence and Space company). Taking off into 2014, EADS was rebranded as "Airbus Group". Uniting all its activities under a single brand, its helicopter division Eurocopter was rebranded as Airbus Helicopters on 8 January 2014.

On 2 March 2009, Eurocopter delivered EC155 B1 s/n 6828 OY-HJA to Helicopter Transportation Group (HTG) that leased the OY-HJA to DanCopter A/S. On 4 March 2009, after the formal handover and after receiving the temporary flight permission as OY-HJA from SLV, the EC155 B1 Dauphin II left Marignane in France on its delivery flight to Esbjerg Airport in Denmark. On 24 March, the 2009-built EC155 B1 was registered OY-HJA in Denmark with DanCopter A/S, Esbjerg, as operator and Helicopter Transportation Group AS, Lysaker, Norway, as owner. On 23 April 2009, EC155 B1 OY-HJA arrived as DOP221 at Den Helder and was a number of years operated out of Den Helder. The EC155 B1 OY-HJA was one of six in service with DanCopter, part of the Blueway Group. On 28 January 2014, Wells Fargo Bank Northwest NA was registered as owner of the OY-HJA with as before DanCopter as operator. In December 2014, NHV Group acquired the Blueway Group, including DanCopter, Blueway Offshore Norway, Airlift and Vertech Offshore. As before, the former DanCopter EC155 B1 OY-HJA was operated by NHV from Norwich Airport (EGSH / NWI) in the UK. From July 2015, after losing their contracts to CHC Scotia, the OY-HJA and the other five DanCopter EC155B1's were stored at Norwich and in the case of OY-HJA at Denham in the UK. In 2017, the OY-HJA received maintenance at Denham. On 28 February 2018, registration OY-HJA was cancelled as sold in the UK. On 2 March 2018, the EC155 B1 was registered G-CKUY in the UK with Waypoint Asset Euro 1A Ltd., Republic of Ireland, as owner. On 23 August 2018, the G-CKUY was flown to the Heli Holland heliport near Emmen for maintenance. On 28 August 2018, registration G-CKUY was cancelled as exported to Germany, and on 21 September 2018, the helicopter was registered D-HNHF with NHC - Northern Helicopter, Emden.
On 24 August 2018, EC155 B1 G-CKUY was seen at the Heli Holland heliport near Emmen.
The ICAO Aircraft Type Designator for both the EC155 and H155 helicopter is EC55.

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