Aircraft History, Specification and Information
Eurocopter AS 355 Ecureuil 2 / TwinStar

The Eurocopter AS355 Ecureuil 2 (Twin Squirrel) is a twin-engine light helicopter originally manufactured by Aérospatiale (now part of Eurocopter Group). The AS355 is marketed in North America as the TwinStar.

Design and development

Development began in the early 1970s to replace the Alouette II, and the first flight took place on 27 June 1974. A twin-engined version, known as the Ecureuil 2, Twin Squirrel, or in North America as the TwinStar, first flew on 28 September 1979. Despite the introduction of the EC130, production of the Eurocopter AS350 and AS355, and the AS550 and AS555 Fennec military versions remains strong.

Both single and twin-engined versions have been built under licence by Helibras in Brazil.


Twin Engine

  • AS355
    Prototype of the twin-engined Ecureuil 2 or Twin Squirrel.
  • AS355 E
    Initial production version, with single hydraulics, powered by two Allison 250 turboshaft engines. Known as the Twin Star in the United States and Canada.
  • AS355 F
    Improved version, now with dual hydraulics, and fitted with improved rotor blades and systems.
  • AS355 F1
    Powered by the Allison C20F engine. 2,400 kg (5,291 lb) M.T.O.W.
  • AS355 F2
    Powered by the Allison C20F engine with uprated engine and transmission for higher M.T.O.W. (2,540 kg or 5,600 lb), and hydraulic accumulator for better tail rotor control.
  • AS355 M
    Initial armed version of AS355 F1.
  • AS355 M2
    Armed version of AS355 F2. Superseded by AS555 Fennec.
  • AS355 N Ecureuil 2
    Version fitted with two Turbomeca Arrius 1A engines and a Full Authority Digital Engine Control (FADEC) system for better M.T.O.W (2,600 kg or 5,732 lb) and better single engine performance. Known as the TwinStar in the United States, tail rotor strake added along starboard side of tail boom for better yaw authority.
  • AS355 NP Ecureuil 2
    Introduced in 2007, this version is fitted with two Turbomeca Arrius 1A1 turboshaft engines and a new AS350 B3-based main gearbox, increasing maximum take-off weight to 2,800 kg (6,173 lb).
  • HB.355F Esquilo Bi
    Licence built in Brazil by Helibras.
  • HB.355N Esquilo Bi
    Licence built in Brazil by Helibras.

Aftermarket conversions

  • Heli-Lynx 355FX1
    Powered by the Allison C20F engine. FAA, TC, and EASA approved.
  • Heli-Lynx 355FX2
    Powered by the Allison C20F engine. FAA,TC and EASA approved.
  • Heli-Lynx 355FX2R
    Powered by the Allison C20R engine. FAA and TC approved.
  • Starflex AS355F1R
    AS355 F1 powered by the Allison C20R engine. FAA, TC and EASA approved.
  • Starflex AS355F2R
    AS355 F2 Powered by the Allison C20R engine with optimised tail rotor blades. FAA, TC and EASA approved.

Military operators

  • Algeria
    Algerian Air Force - AS355.
  • Brazil
    Brazilian Air Force - HB355F2 (designated H-55)
    Brazilian Navy - AS355F2 (designated UH-13)
  • Cambodia
    Royal Cambodian Air Force - 1 AS355.
  • Chile
    Chilean Army HB355
  • Djibouti
    Djibouti Air Force - AS355.
  • France
    French Air Force - AS355.
  • Jamaica
    Jamaica Defence Force AS355N
  • Malawi
    Malawi Army - AS355.
  • Rwanda
    Rwandan Defence Forces - 1 SA 355F
  • Uruguay
    National Navy of Uruguay - AS355.
  • Trinidad and Tobago
    Special Anti-Crime Unit of Trinidad & Tobago (SAUTT) — operates one AS355 F2.
  • Venezuela
    Venezuelan National Guard - AS355.
  • Pakistan
    Pakistan Army - AS355.

Law Enforcement operators

  • Austria
    Flugpolizei (Ministry of Interior) operates two AS355 F2s and two AS355 Ns.
  • Belarus
    Border Guard operates four AS355NP Ecureuil 2 (based in Pastavy).
  • Canada
    Ontario Provincial Police AS335F2R TwinStar
  • Ireland
    AS355N Squirrel was in use by Garda Air Support Unit up until January 2008.
  • New Zealand
    New Zealand Police operate two AS355 F1 helicopters providing air support primarily to the greater Auckland region.
  • Philippines
    Philippine National Police
  • Trinidad and Tobago
    Special Anti-Crime Unit of Trinidad & Tobago (SAUTT) — operates one AS355 F2 for the Ministry of National Security
  • United States
    Massachusetts State Police operates 4 AS355 N TwinStars.
    Salt Lake County Sheriff operates an AS355 N helicopter.
  • Malaysia
    Royal Malaysia Police Operates AS 355 Twin Squirrel.
  • Mexico
    Mexico City Police Department, Condores Operates AS 355N

Civilian operators

  • Australia
  • Bhutan
  • Trinidad and Tobago
    Briko Air Services - operates one AS355 F2
  • Chile
    DAP Helicópteros (AS355)
  • United Kingdom
    Arena Aviation own & operate four Twin Squirrels for TV news gathering & aerial filming.
    CabAir Helicopters operate a number of Twin Squirrel "VIP Version" helicopters.
  • Hong Kong
    Heli Express
  • India
    Raymond Ltd. ( Aviation Div.)
    Sahara Helicopters (Helicopter Div.)
  • Liechtenstein
    Rhein-Helikopter AG
  • Philippines
    ABS-CBN Broadcasting Corporation uses AS355 as its news helicopter equipped with a High Definition camera (ABS-CBN Sky Patrol)
  • United States
    AirMed/Gold Cross EMS operates one TwinStar medical evacuation helicopter.
  • Slovakia
    Slovak HEMS - ATE
  • Norway
    European Helicopter Center operates one AS355N

Accidents and incidents

On 22 October 1996, Chelsea Football Club Vice Chairman Matthew Harding together with five companions were killed when their AS355 F1 Squirrel, registration G-CFLT, crashed near Middlewich, Cheshire.

In July 1998, the Kent Air Ambulance, a AS355 F1 Squirrel, crashed in good weather after colliding with power cables near Burham whilst returning to Rochester Airport following an aborted call to attend a road accident. All three crew - the pilot, Graham Budden, and two paramedics, Tony Richardson and Mark Darby - were killed on impact. The crash was ultimately attributed to mechanical failure.

In May 2007, Chelsea Football Club Vice President Philip Carter, founder of training company Carter and Carter, crashed in his part-owned Twin Squirrel registration G-BYPA returning from Liverpool John Lennon Airport after watching Chelsea play Liverpool F.C.

On 18 August 2011, a AS-355F-2 (reg No/ VH-NTV) crashed near Lake Eyre in South Australia resulting in 3 fatalities. The Helicopter was owned by the Australian Broadcasting Corporation. On board were, Gary Ticehurst (abc chief helicopter pilot for 25 years), John Bean (cameraman) and Paul Lockyer (journalist). All three had 20 years or more experience working for the ABC.

On 20 October 2011, the Eurocopter twin-engine helicopter crashed at 3:45 p.m. (1245 GMT) near the village of Vileity and burst into flames. A Belarus border patrol helicopter crashed Thursday near the Lithuanian border, killing all five people on board, including three members of a television crew, the agency said.

Specifications (AS355F2)

General characteristics
Crew: 1
Capacity: 6
Length: 12.94 m (42 ft 5½ in)
Rotor diameter: 10.69 m (35 ft 0¾ in)
Height: 3.14 m (10 ft 3½ in)
Disc area: 89.75 m² (966 sq ft)
Empty weight: 1,305 kg (2,877 lbs)
Max takeoff weight: 2,600 kg (5,732 lbs)
Powerplant: 2 × Allison 250-C20F turboshaft, 313 kW (420 shp) each

Never exceed speed: 278 km/h (150 knots, 172 mph)
Cruise speed: 224 km/h (121 knots, 139 mph)
Range: 703 km (380 nm, 437 mi)
Service ceiling: 3,400 m (11,150 ft)
Rate of climb: 6.5 m/s (1,280 ft/min)

Last updated November 17, 2011
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Eurocopter AS355".
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