The Airbus Helicopter Ecureuil Family

v2.0.3 / 01 nov 16 / greg goebel

* 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 / Airbus Helicopters, Aerospatiale's successor firm. This document provides a history and description of the Ecureuil family, including the "EC 120 / EC 130" follow-ons.

Airbus Helicopters AS 350B2 Ecureuil



* 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. 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.

Airbus Helicopters AS 350B2 Ecureuil

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. EADS would become the "Airbus Group" in 2014, with Eurocopter renamed "Airbus Helicopters"; the 21st-century name is used in the text below for simplicity. As a result, the AS 350B2 and AS 350B3 are now, despite their "AS" designations, Airbus Helicopter products.

Airbus Helicopter AS 350B3 Ecureuil

The Ecureuil remains a component of Airbus Helicopter 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. Airbus Helicopter introduced an "AS 350B3e" in 2011, featuring an Arriel 2D engine with 12% more power and the ability to maintain 635 kN (850 SHP) takeoff power for 30 minutes.

   _____________________   _________________   _______________________
   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.

Airbus Helicopter AS 355B2 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.



* 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.

Danish AS 550 Fennec

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.

Columbian Navy AS 555SN Fennec

* 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 Airbus Helicopter 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; new communications and navigation systems; an automatic flight control system; more armor; and new seats to provide improved crash protection. The first of 36 machines to be upgraded was redelivered in early 2015, the last 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.



* 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 Airbus Helicopter, with a tri-national design team working out of the Airbus Helicopter 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 -- with "EC" standing, of course, for "Eurocopter", though that designation is no longer meaningful. A second prototype took to the air on 17 July 1996. Initial certifications followed in 1997, with initial deliveries in 1998.

Airbus Helicopter EC 120 Colibri

* 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 Airbus Helicopter.

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.

   _____________________   _________________   _______________________
   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.

Airbus Helicopter handled 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.

The European Community is now working on a "Clean Sky" program for environmentally friendly aircraft operations, with the effort including a "Green Rotorcraft (GRC)" investigation. One aspect of GRC is development of a lightweight, fuel-efficient turbocharged diesel engine for helicopters, with Austro Engine now working on such an engine, to be ground-tested in an EC 120 in 2014. Whether that leads to a production machine of course remains to be seen.



* The Colibri was well-received by customers, and so Airbus Helicopter 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 130 B4 -- as the initial production version was designated -- was very similar to the EC 120 but larger, with 23% more cabin space and greater load capacity. It carried a pilot plus 6 or 7 passengers, or 1 or 2 stretchers with a medical attendant. It had an external sling attachment with a maximum load capacity of 1,160 kilograms (2,558 pounds). The EC 130B4 was 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.

Airbus Helicopter EC 130 B4

The EC 130 B4 was 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 had a heavy-duty air-conditioning system to keep tourists cool, and the pilot sat the left, not on the right as is traditional, a change driven by feedback from sightseeing and medevac operators.

The EC 130 B4 featured 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.

   _____________________   _________________   _______________________
   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       260 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.

In 2012, Airbus Helicopter unveiled the latest variant of the series, the "EC 130 T2", which retained the same external appearance but featured substantial airframe and a revised interior, along with an active vibration control system, improved serviceability, and a modernized control layout. In particular, it featured an Arrius 2D engine and an uprated drivetrain to handle the additional power, providing heavier takeoff weight and higher speed, along with lower fuel consumption. Production deliveries of the EC 130 T2 began in 2013.

Overall total sales of the Ecureuil family are running at about 4,000 machines, with users in at least 70 countries. The Ecureuil has been and continues to be a nice little earner for Airbus Helicopter.



* As concerns copyrights and permissions for this document, all illustrations and images credited to me are public domain. I reserve all rights to my writings. However, if anyone does want to make use of my writings, just contact me, and we can chat about it. I'm lenient in giving permissions, usually on the basis of being properly credited.

Airbus Helicopter EC 130 T2

* 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 Airbus Helicopter 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 / Initial release with both Ecureuil & Dauphin.
   v1.0.1 / 01 may 10 / Minor update.
   v2.0.0 / 01 feb 11 / Split out materials on Dauphin.
   v2.0.1 / 01 jan 13 / Added EC 130 T2.
   v2.0.2 / 01 dec 14 / Changed "Eurocopter" to "Airbus Helicopter".
   v2.0.3 / 01 nov 16 / Review & polish.