* The Aerospatiale company of France became a global player in the helicopter market through its popular "Alouette" series of light helicopters. Following up on this success, in the 1970s the firm developed a series of rotorcraft, including a new light helicopter named the "Ecureuil (Squirrel)", which proved popular as well and remain in production with Eurocopter, Aerospatiale's successor firm. This document provides a history and description of the Ecureuil family, including the "EC 120 / EC 130" follow-ons.
* In the early 1970s, the Aerospatiale firm of France began work on a light utility helicopter to replace the company's popular Alouette series of rotorcraft. The result was the "AS 350", with first flight of the initial prototype, powered by an Avco Lycoming LTS 101 turboshaft engine, on 27 June 1974. A second prototype, powered by a Turbomeca Arriel 1A turboshaft, followed on 14 February 1975. The Lycoming engine fit was intended for sales in North America, while the Turbomeca engine fit was for Europe and elsewhere.
Not surprisingly given the difference in markets, the Turbomeca-powered line ended up predominating, with the initial production "AS 350B Ecureuil (Squirrel)" being certified in late 1977 and deliveries in 1978. It was offered in a variety of fits for applications such as emergency medical services and police work.
The AS 350B was powered by an Arriel 1B turboshaft providing 480 kW (640 SHP) and was of conventional configuration, with a three-blade fiberglass main rotor coupled to a fiberglass / elastomer "Starflex" hub; a two-blade tail rotor on a tailfin, with a ventral fin below; and skid landing gear. The Ecureuil featured a relatively high proportion of plastic and fiberglass assemblies.
The Ecureuil had two seats in front and a bench seat for up to four in the back, with a default door scheme of a single big forward-hinged door in front on each side. An alternate door scheme, with a smaller cockpit door forward and a rear-sliding main door on each side, was also offered. It is unclear if the four-door option was available on the original AS 350B, this scheme being associated with the AS 550 military variants of the Ecureuil -- see below -- but it is not unusual with later AS 350 civil variants. There was a baggage hold in the rear, with a top-hinged door on the right.
The Ecureuil was designed to be reliable, economical to operate, and relatively quiet. Ironically, the Alouette series proved to be resilient, with the modernized Gazelle variant continuing to sell well, and the Ecureuil ended up complementing its sales.
The AS 350B led to a series of refined variants:
In 1992, the helicopter division of Aerospatiale merged with the German Messerschmitt-Boelkow-Blohm firm to form "Eurocopter", which would later become part of the "European Aerospace & Defense Systems (EADS)" group. As a result, the AS 350B2 and AS 350B3 are now, despite their "AS" designations, Eurocopter products.
The Ecureuil remains a component of Eurocopter product line, being sold with possible options such as an external sling, rescue host, inflatable flotation gear, video camera, searchlight, imaging turret, and agricultural spraytank.
EUROCOPTER AS 350B3 ECURIEUL: _____________________ _________________ _______________________ spec metric english _____________________ _________________ _______________________ main rotor diameter 10.69 meters 35 feet 1 inch fuselage length 10.93 meters 35 feet 10 inches footprint length 12.94 meters 42 feet 6 inches height (tail) 3.14 meters 10 feet 4 inches empty weight 1,175 kilograms 2,590 pounds MTO weight 2,250 kilograms 4,960 pounds max cruise speed 250 KPH 155 MPH / 135 KT service ceiling 5,280 meters 17,325 feet hover ceiling (1) 3,535 meters 11,600 feet hover ceiling (2) 2,880 meters 9,450 feet range 640 kilometers 400 MI / 345 NMI _____________________ _________________ _______________________ (1) hover ceiling in ground effect (2) hover ceiling out of ground effect.
* The Avco Lycoming-powered variants of the AS 350 were developed in parallel with the Turbomeca-powered variants, with the "AS 350C AStar" introduced in 1978. It was powered by an Avco Lycoming LTS101-600A2 turboshaft providing 460 kW (615 SHP). It was replaced in 1978 by the "AS 350D AStar", which was equivalent to the AS 350B2 and powered by an LTS101-600A3 turboshaft with 460 kW (615 SHP). However, it appears that the Lycoming powerplant proved unsatisfactory, and though the AStar continues to be sold in the USA, now it's just a rebadged Turbomeca Ecureuil.
* In 1978, work began on a twin-engine derivative, the "AS 355E Ecureuil 2", the twin engines providing greater safety and lift capacity. Initial flight of the first of two prototypes was on 28 September 1979. The result was very similar to the AS 350 but was powered by twin Allison 250-C20 turboshafts providing 315 kW (420 SHP) each. In North America, the Ecureuil 2 was sold as the "Twinstar". The AS 355E was followed by:
Specs of the AS 355N are very similar to those of the AS 350B3, dimensions being effectively identical, though the AS 355N's empty and MTO weight are about 15% greater. Other than the engine fit, there were some detail differences, for example three baggage holds instead of one. Optional gear was much the same as for the AS 350.
BACK_TO_TOP* While some military forces bought the Ecureuil for training and utility use, sales to armed services didn't pick up until Aerospatiale decided to develop a specific military series. The "AS 350L" was the first specifically military Ecureuil, being effectively an AS 350B1 with the Arriel 1D engine, but with taller landing gear, raising the machine's height by 20 centimeters (8 inches); the sliding door fit described above; extended instrument fit; a stores pylon on each side, bolstered with airframe reinforcements for weapons carriage and firing; plus provision for armored seats, cable cutters, and combat avionics such as defensive countermeasures systems and optical / infrared imager turrets.
Initial flight of the AS 350L was in March 1985, with deliveries beginning in 1986. It was followed by the "AS 350L2", which was renamed "AS 550U2" in 1990, the decision having been made that the military variants needed their own product line code, as well as a new name: "Fennec (Desert Fox)". The AS 550U2 was actually the general utility version, with other subvariants featuring different equipment fits and suffixes:
An improved "AS 550U3" was introduced to replace the AS 550U2, the new variant featuring the Arriel 2B engine of the AS 350B3; of course "AS 550A3", "AS 550C3", "AS 550M3", and "AS 550S3" subvariants were offered as well.
* The twin-engine AS 355s were given a similar military makeover. The French Air Force was an early user, obtaining eight AS 355F1 civil machines with Allison engines and militarizations, particularly the capability to carry the side-mounted GIAT 20 millimeter cannon. However, the military versions quickly went on to the fully-militarized "AS 555" series, with TM 319 Arrius 1A engines as per the AS 355N. AS 555 configurations included:
* The following table summarizes Ecureuil / Fennec variants:
variant notes ____________________________________________________________________ AS 350 Ecureuil prototype. AS 350B Initial production variant with Arriel 1B engine. AS 350BA AS 350B with wide-chord rotor blades. AS 350B1 Arriel 1D engine, wide-chord rotor blades. AS 350B2 Arriel 1D1 engine. AS 350BB AS 350B2 modification for UK military. AS 350B3 Arriel 3B engine, stronger gearbox, wider tail rotor. ____________________________________________________________________ AS 350C US-only AStar with LTS101-600A2 engine. AS 350D US-only AStar with LTS101-600A3 engine. ____________________________________________________________________ AS 355E Allison 250-C20 engines. AS 355F AS 355E with wide-chord rotor. AS 355F1 AS 355F1 with greater takeoff weight. AS 355F2 Further increment in takeoff weight. AS 355N Turbomeca TM 319 Arrius 1A engines. ____________________________________________________________________ AS 350L Initial military variant, Arriel 1D engine. AS 550U2 Military utility variant, originally AS 350L2. AS 550C2 Anti-armor variant. AS 550A2 Infantry support variant. AS 550M2 Naval utility variant. AS 550S2 Maritime combat variant. AS 550U3 Improved military utility variant with Arriel 2B engine. AS 550C3 Improved anti-armor variant. AS 550A3 Improved infantry support variant. AS 550M3 Improved naval utility variant. AS 550S3 Improved maritime combat variant. AS 555UN Army utility twin with TM 319 Arrius 1A engines AS 555AN Army armed twin. AS 555MN Naval utility twin. AS 555SN Naval armed twin. ____________________________________________________________________
* There has been substantial foreign license production of the Ecureuil family. Helibras of Brazil, a joint venture of Aerospatiale and several Brazilian firms established in the late 1970s, built the Ecureuil under license as the "Esquilo" -- Portuguese for "Squirrel" of course. Sales were good, with deliveries not merely to Brazilian customers but to other buyers all over South America, particularly military users. The Brazilian-branded Ecureuils ended up with a confusing array of designations:
helibras_variant notes ____________________________________________________________________ HB 350B1 Same as AS 350B1. HB 350B2 Same as AS 350B2. HB 350L1 Same as AS 350L1 army single. HB 355F1 Same as AS 355F1 twin. HB 355F2 Same as AS 355F2 twin. ____________________________________________________________________ HA-1 Brazilian Army AS 350L1, with armament capability. CH-50 Brazilian Air Force HB 350B/B1. TH-50 Trainer variant of CH-50. CH-55 Brazilian Air Force HB 355F2 twin. VH-55 VIP transport variant of CH-55. UH-12 Brazilian Navy HB 350B, with armament capability. UH-12B Brazilian Navy HB 355F2, with armament capability. ____________________________________________________________________
Along with sales of Brazil-built machines, Helibras handles regional sales of Eurocopter machines not built in Brazil.
In 2010, the Brazilian Army initiated an upgrade program with Helibras for its machines, to involve a new glass cockpit with three large color displays, an automatic flight control system, and new seats to provide improved crash protection. The last of 36 machines to be upgraded is to be redelivered in 2018. Other Brazilian users are likely to obtain much the same upgrade.
* The Ecureuil is also built in China by the Change / CHAIG organization as the "Z-11". Initial flight of a Chinese-production machine was in 1997; the initial production variant was apparently equivalent to the AS 350B2, with an Arriel 1D turboshaft, license-built as the WZ8D, but featured a longer and sharper nose. It was followed in 2003 by the "Z-11MB1" with an Arriel 2B1A turboshaft. The Z-11 series is offered in various civil and military configurations, but no twin-engine variant has appeared just yet.
BACK_TO_TOP* In 1992, Aerospatiale began to investigate a new entry-level single-engine helicopter, initially designated the "P120L". The company also began a hunt for cost-sharing partners to help fund development, with Harbin Aircraft Manufacturing Company (HAMC) of China and Singapore Technologies Aerospace (STA) signing up. Formal development of the new helicopter began in early 1993, the same year Aerospatiale became part of Eurocopter, with a trinational design team working out of the Eurocopter facility at Marignane, France. The first prototype of the "EC 120 Colibri (Hummingbird)", as the new helicopter was designated, performed its initial flight on 9 June 1995. A second prototype took to the air on 17 July 1996. Initial certifications followed in 1997, with initial deliveries in 1998.
* The appearance of the EC 120B -- as the initial production variant was designated -- does not immediately suggest much relationship to the earlier Ecureuil series of helicopters. It shares much of the technology of the older series, including tailboom, engines, power transmission, and gearbox, but features a new "widebody" cabin and also an eight-blade "fenestron" (enclosed) tail rotor. The widebody cabin appears to have due to a bit of "cross pollination" with the helicopters designed by the German MBB firm, the other ancestor of Eurocopter.
The Colibri can carry a pilot, with 3 or 4 passengers or a stretcher with a medical attendant. It was designed with relatively quiet operation in mind -- the tail rotor blades are unevenly spaced to reduce noise. The Colibri is powered by a Turbomeca Arrius 2F turboshaft engine with 375 kW (505 SHP) for takeoff, driving a three-blade rotor with composite blades and a Spheriflex titanium hub. The fuselage is built of light alloy and composites and features twin landing skids. The EC 120 has a partial "glass cockpit" with twin flat-panel displays. Options include flotation gear and a searchlight.
EUROCOPTER EC 120B COLIBRI: _____________________ _________________ _______________________ spec metric english _____________________ _________________ _______________________ main rotor diameter 10 meters 32 feet 10 inches fuselage length 9.60 meters 31 feet 6 inches footprint length 11.52 meters 37 feet 9 inches height (tail) 3.50 meters 11 feet 6 inches empty weight 960 kilograms 2,117 pounds MTO weight 1,800 kilograms 3,969 pounds max cruise speed 228 KPH 142 MPH / 123 KT normal cruise speed 191 KPH 119 MPH / 103 KT service ceiling 5,365 meters 17,600 feet hover ceiling (1) 2,820 meters 9,250 feet hover ceiling (2) 2,320 meters 7,600 feet range 732 kilometers 455 MI / 395 NMI _____________________ _________________ _______________________ (1) hover ceiling in ground effect (2) hover ceiling out of ground effect.
Eurocopter handles overall design, engineering, and integration of the Colibri, and produces the drive train, avionics, and electrical system. HAMC has a 24% share and produces the fuselage, including fuel system and canopy. STA has a 15% share and produces the tailboom, access doors, and windshields.
BACK_TO_TOP* The Colibri was well-received by customers, and so Eurocopter went on to develop a more capable derivative. Initial studies were conducted in 1998, and the initial prototype of the "EC 130", as it was designated, performed its first flight on 24 June 1999. The second prototype flew in September 2000, with international certifications obtained by the end of the year. Initial customer delivery was in 2001.
The EC 130B4 -- as the initial production version was designated -- is very similar to the EC 120 but was larger, with 23% more cabin space and greater load capacity. It carries a pilot plus 6 or 7 passengers, or 1 or 2 stretchers with a medical attendant. It has an external sling attachment with a maximum load of 1,160 kilograms (2,558 pounds). The EC 130B4 is powered by a single Turbomeca Arriel 2B1 turboshaft, with a dual channel FADEC and 632 kW (847 SHP) take-off power, driving a three-blade composite rotor and a fenestron tail rotor.
The EC 130B4 is even quieter than the EC 120, since it was designed partly with the tourism market in mind and meets the strict noise requirements set for the US national parks. It has a heavy-duty air-conditioning system to keep tourists cool, and the pilot sits on the left, not on the right as is traditional, a change driven by feedback from sightseeing and medevac operators.
The EC 130B4 features assemblies from the EC 120, including doors and canopy (with a distinctive new central window); engine, drivetrain, rotor, and hydraulics from the Ecureuil series; and new assemblies, such as a metal tail boom and new landing gear. It can be a bit difficult to tell an EC 130 from an EC 120; one of the main recognition features is that the EC 130 has a three-part windscreen, with a center panel, while the EC 120 has a two-part windscreen. The EC 130 also has a "fat" tailfin that clearly differs from that of the EC 120.
EUROCOPTER EC 130B4: _____________________ _________________ _______________________ spec metric english _____________________ _________________ _______________________ main rotor diameter 10.69 meters 35 feet 1 inch fenestron diameter 1 meter 3 feet 6 inches fuselage length 10.68 meters 35 feet footprint length 12.64 meters 41 feet 6 inches height (tail) 3.61 meters 11 feet 10 inches empty weight 1,360 kilograms 3,000 pounds max loaded weight 2,800 kilograms 6,174 pounds fast cruise speed 259 KPH 160 MPH / 140 KT service ceiling 7,010 meters 23,000 feet hover ceiling (1) 3,100 meters 10,165 feet hover ceiling (2) 2,540 meters 8,325 feet range 640 kilometers 400 MI / 345 NMI _____________________ _________________ _______________________ (1) hover ceiling in ground effect (2) hover ceiling out of ground effect.
* Overall, total sales of the Ecureuil family are running at close to 4,000 machines, with users in at least 70 countries. The Ecureuil has been and continues to be a nice little earner for Eurocopter.
BACK_TO_TOP* Helicopters are not over-documented, and so this writeup was put together by scanning through all the JANE'S ALL THE WORLD AIRCRAFT volumes I could find that mentioned these machines, as well as searches of the internet for useful clues. The Eurocopter website had a fun little interactive utility that allowed me to pick semi-custom paint schemes for the EC 130.
This document started life covering both the Aerospatiale Dauphin / Panther medium helicopter along with the Ecureuil, but it got too long and I had to split them out into separate documents.
* Revision history:
v1.0.0 / 01 oct 09 / gvg / Initial release with both Ecureuil & Dauphin. v1.0.1 / 01 may 10 / gvg / Minor update. v2.0.0 / 01 feb 11 / gvg / Split out materials on Dauphin.BACK_TO_TOP
