Aérospatiale/Eurocopter AS355 Écureuil 2

Updated: October 2026 – A helicopter with a large glass cockpit circles for minutes over a stadium, a traffic jam or a police operation, a camera ball hanging under the fuselage. You think “Ecureuil” – and you are often right. But which one? The AS355 Écureuil 2, called the TwinStar in North America, is the twin-engine version of the famous French Ecureuil family. For authorities and TV crews, it was the first choice for decades. Here you learn how to tell it from the single-engine H125, which variants exist and where you can still get one in front of your lens today.

What is the AS355 Écureuil 2?

The AS355 is a light twin-engine helicopter in the two-and-a-half-tonne class. It descends from the AS350 Écureuil, which Aérospatiale developed in the early 1970s at Marignane near Marseille as an affordable, civil-oriented successor to the Alouette II. Chief designer René Mouille consistently focused on cost-effectiveness: the fuselage was made from rolled sheet metal, a technique from car manufacturing, and the main rotor got the new Starflex rotor head, which gets by with far fewer moving parts than classic articulated rotors.

The single-engine AS350 first flew in 1974, and the twin-engine version followed on September 28, 1979. The idea was simple: the same airframe, the same rotors, but two smaller turbines instead of one large one. That appealed to customers who valued a second turbine for flights over cities, over water or at night. Depending on the market, the helicopter was called Écureuil 2 (Squirrel 2), Twin Squirrel or TwinStar.

Aérospatiale became Eurocopter in the 1990s, then Airbus Helicopters in 2014. You can find more about today’s manufacturer on the Airbus Helicopters page and about the parent group on Airbus.

In September 2015, Airbus Helicopters announced it would phase out the AS355 to concentrate on more in-demand types. Existing orders were still worked off until 2016. The single-engine sister, by contrast, kept going and is today, as the H125, one of the most-built helicopter types of all: Airbus puts the entire Ecureuil family at more than 7,200 aircraft delivered.

The variants at a glance

Over almost four decades of production, the AS355 changed several times. The most important dividing line runs between the Allison versions and the later Arrius versions.

Variant	Engines	Special feature	Max. takeoff weight
AS355 E	2 × Allison 250-C20F	first production version, single hydraulics	–
AS355 F	2 × Allison 250-C20F	dual hydraulics	2,300 kg
AS355 F1	2 × Allison 250-C20F	higher weight	2,400 kg
AS355 F2	2 × Allison 250-C20F	yaw compensation, heavier again	2,540 kg
AS355 N	2 × Turbomeca Arrius 1A	digital engine control (FADEC)	2,600 kg
AS355 NP	2 × Turbomeca Arrius 1A1	main gearbox from the AS350 B3, from 2007	2,800 kg

The Allison 250 belongs today, as the Rolls-Royce M250, to the portfolio of Rolls-Royce, and the Arrius family to Safran, the successor to Turbomeca. The AS355 NP of 2007 was the last major upgrade: more powerful engines, the robust gearbox of the AS350 B3 and the highest takeoff weight of the series.

There were also military offshoots. The armed AS355 M and M2 were replaced by the AS555 Fennec, the military sister of the Écureuil 2. In Brazil, Helibras assembled AS350s and AS355s from kits from Marignane; the twin-engine version is called Esquilo Bi there and flew with the navy and air force, among others.

How to recognize the AS355

The bad news first: from a distance, the AS355 and AS350/H125 look almost the same. Cockpit, tail boom, tail, skids and rotor are closely related. The good news: a look at the roof is enough in most cases.

How registrations are structured and where to find the registers is explained in the article Understanding aircraft registrations. For older aircraft, a look at the year of manufacture is also worthwhile – how to find it out is in the guide Finding out an aircraft’s age.

AS355 or H125? The distinction in detail

Confusion with the H125 is the classic. No wonder: the H125 is the current designation of the single-engine AS350 B3e, sold in North America as the AStar. It has carried the name H125 since 2016. It flies with a single Safran Arriel 2D and is known above all for performance at high altitude and for load-carrying flights. It is presented in detail on the page for the Airbus H125.

Feature	AS355 Écureuil 2	AS350 / H125
Turbines	two	one
Exhaust outlets	two	one
Engine cowling	wider, boxier	narrower
Main rotor	three blades, Starflex	three blades, Starflex
Tail rotor	open, two blades	open, two blades
ICAO code	AS55	AS50
Production	until 2016	continues

One difference lies more in the operating profile than in appearance: the H125 is the work helicopter for mountains, external loads and sightseeing flights, while the AS355 was the twin for the city, authorities and media. So if you see an Ecureuil with a camera ball over a city center, a second look at the roof is especially worthwhile.

The H130, by the way, emerged from the AS350 and also carries Ecureuil genes, but differs clearly through its shrouded tail rotor. A general guide to all common types is in the article Recognizing helicopter types.

Police and media helicopters

The strengths of the AS355 match exactly the requirements of police and television: two turbines for more safety over built-up areas, a large cockpit with a clear view forward and downward, a handy size and comparatively low operating costs for a twin.

Police: Police units in many countries have used the AS355, for example in the United Kingdom, in Canada with the Ontario Provincial Police or with the Royal Malaysian Police. The Austrian Interior Ministry also had the AS355 in its fleet. Typical are a thermal imaging and camera ball at the nose, a searchlight and radio antennas on the fuselage. Many authorities have meanwhile replaced their AS355s with newer types like the H135 or the H145, the Ontario Provincial Police for example with the EC135 – so sightings of police Ecureuils are getting rarer.

Media: TV stations liked to use the AS355 as a camera helicopter for news, sports coverage and traffic reports; in Australia, for example, the broadcaster ABC flew an AS355 as a news helicopter. The stabilized camera systems usually hang at the nose or on the side of the fuselage.

Charter and aerial work: In addition, many AS355s are out and about with charter, training and aerial work operators, for example for photo and survey flights, power line inspections or corporate flights. Used Allison aircraft in particular have changed owners several times.

Location	Chance of a hit	Why
Helipads and heliports	medium	Charter and aerial work operators are based here
Major events, stadiums, city centers	medium	Camera and police flights
Regional airports and airfields	medium	Maintenance, fuel stops, ferry flights
Large commercial airports	low	Helicopters mostly use their own sites
Air days and military events	low to medium	static displays, Fennec versions

Many helicopters transmit ADS-B data and show up in flight tracking services under the code AS55. Police flights, however, are often filtered – why is explained in the article Why an aircraft doesn’t show up on Flightradar. How to track down rescue, police and aerial work helicopters anyway is explained in the article Tracking helicopters on the flight tracker.

Why the AS355 is disappearing

The end of the AS355 has several reasons. For one, modern light twins with larger cabins came onto the market from the 1990s, above all the EC135, which flies today as the H135. It offers a Fenestron, rear doors for stretchers and a more modern layout – features that became more important for air rescue and police. For another, single-engine helicopters like the AS350 B3 became ever more capable, so that one turbine is enough for many aerial work flights.

Airbus Helicopters drew the conclusion in 2015 and announced the end, and production ran out in 2016. For spotters, that means: every AS355 is at least around ten years old, and many aircraft have three or four decades behind them. The fleet is slowly shrinking, and with every retirement the Twin Squirrel becomes a little more of a collector’s item for your hangar. Ideas for finding such rarities deliberately are provided by the article Spotting rare aircraft; to judge how special your sighting is, How rare is my sighting? helps.

Photo tips for the Twin Squirrel

With helicopters, the shutter speed decides the effect of the picture. With a very short exposure, the three rotor blades stand still and the helicopter looks like a model. With a longer exposure, they blur into a disc and the picture gains dynamism.

More on the technique is in the guide Photographing propellers: the right shutter speed, which transfers one to one to rotors. General tips on rotary-wing aircraft are collected in the article Spotting helicopters. When the light works at your location, you find out with the Planetrack sun position planner; the basics are explained in the guide Planning the sun position.

Common mix-ups and how to rule them out

Conclusion

The AS355 Écureuil 2 is the Ecureuil for spotters with a trained eye: from below it looks like any H125, and only the two exhaust pipes and the wide engine cowling give away the twin. For decades it was the workhorse of police and television; it has not been built since 2016, and with every retirement it gets rarer. If you catch one, a clean photo from an angle behind and a look in the register are worthwhile – then you also know whether you had a classic Allison F2 or a late Arrius NP in front of your lens. If you are new to the hobby, you will find the right starting point in the introduction Plane spotting for beginners.