The programme was launched in September 1996, as further development of the Dauphin 2. Announced at the 1997 Paris Air Show, when known as the AS 365N4 Dauphin 2, with a wide 12-passenger fuselage, five-blade main rotor and improved avionics suite.
The first flight was as a conversion of DGV testbed F-WDFK (AS 365N3 Dauphin 2), on 16 June 1997. 1,000 flying hours was achieved by February 1998.
The new, EC 155 designation was revealed at the February 1998 HAI convention.
The first production EC 155 (F-WWGZ) flew on 11 March 1998 and JAR certification was received on 9 December 1998. Certification for single pilot in IFR issued 25 January 2000.
The EC 155B1, compared to earlier Dauphin models, has bulged sliding cabin doors, redesigned cabin windows and 40% larger cabin area. Five-blade Spheriflex main rotor and 10-blade Fenestron rotor with unevenly spaced blades to reduce noise.
Power is from two FADEÑ-equipped Turbomeca Arriel 2C2 turboshafts, each rated at 697kW for T-O, 645kW max continuous power and 780kW for 30 seconds. Standard fuel in six tanks, total capacity 1,257 litres; provision for auxiliary tank in baggage compartment, with capacity for 180 litres; or ferry tank in place of rear seats in cabin, capacity 460 litres; refuelling point above landing gear door on port side. Oil capacity 14 litres.
Standard accommodation for pilot and copilot or passenger in front, and three rows of four seats to rear; high-density seating for one pilot and up to 14 passengers; VIP configurations for between four and eight persons in addition to pilot; 12 cabin seats in offshore version, up to six stretchers in casevac role; one crew door and one large sliding door on each side; freight hold aft of cabin rear bulkhead, with door on both sides. Option of hinged cabin door on VIP versions.
Electrical system includes two starter/generators, each 160 A, 28 V DC and 43 Ah Ni/Cd battery. Duplicated hydraulic system. Optional 10 kVA alternator.
The first customer, German Border Guard (Bundesgrenzschutz; BGS), ordered 13 for delivery between 16 March 1999 and 2000 and further two in February 2002 for delivery in 2003. German Interior Ministry ordered two for Baden-Wurttemberg regional government in February 2000 for delivery in March 2001; Hong Kong Government Flying Service ordered five of which last delivered 17 December 2002; firm orders stood at 33 by June 2000, of which eight were placed in 1999. Orders in 2000 totalled seven, six of which were placed by Shell Nigeria, whose first aircraft was delivered on 25 September 2001. Swedish Helicopter Service ordered three in June 2001 for delivery between October and December 2002. By October 2001, 44 had been ordered of which 18 were in service. First Nigerian example handed over 26 September 2001. Sales in 2001 totalled 13, including three for COHC (China), two for SFC (Vietnam) and three for SHS (Sweden). Further 13 purchased by BGS in February 2002.
EC 155B: Baseline version; replaced in 2002; MTOW 4,800kg and Arriel 2C1 engines.
EC 155B1: Upgraded version from 2002; as described. Features include new engine cowlings, new hydraulic cooling system, chip detectors, cargo fire protection, jettisonable cockpit doors; fixed cockpit footsteps and Thales AHV 16 radar altimeter display. Available with standard Corporate, Offshore and Parapublic equipment packages.
EC 155B HTT: Helicoptere Tous Temps (all-weather helicopter). Technology demonstrator (F-WQEZ), first flown 15 October 2002, for evaluation of helicopter navigation, ground collision avoidance and autopilot systems.