Eurocopter AS355

The success of the single-engine AS350 created a natural demand for a twin-engine version. Operators wanted the same versatility, reliability, and low operating costs, but with the added safety and performance of two engines. Aérospatiale listened.

Development of the twin-engine Écureuil began early in the model’s development life. The first prototype took to the skies on 28 September 1979. It was directly derived from the single-engined AS350, with many components shared between the two models, including the rotor shaft, main rotor hub, tail rotor hub, servos, cockpit, and landing gear. But the AS355 introduced new main rotor blades, a modified transmission and fuel system, and of course, a second engine. The first production model, the AS355E, was powered by two Allison 250-C20F turboshafts. It was marketed in North America as the TwinStar, a name that captured its twin-engine capability.

The AS355 continued to evolve throughout the 1980s. The AS355F arrived in early 1982 with new wider-chord main rotor blades and a higher maximum takeoff weight. It was followed by the AS355F-1 in January 1984 and the AS355F-2 in December 1985, each introducing progressively higher weights and improved capabilities. The most advanced variant, the AS355N, introduced twin Turbomeca TM-319 Arrius turboshafts and was certificated in 1989, with first deliveries taking place in early 1992.

Why does this matter today? Because the AS355 is still flying, and it is still serving critical missions. In July 2026, Greek charter flight provider Hoper added an AS355 to its fleet to meet high demand during the summer vacation season. The helicopter’s large windows offer tourists excellent views of the Aegean Sea, while its twin-engine reliability ensures passenger safety. The AS355 also continues to serve law enforcement and government agencies worldwide.

In September 2015, Airbus Helicopters announced that AS355 production would continue through 2016 to fulfill existing orders, after which the type was discontinued. But the AS355’s legacy lives on in the thousands of aircraft that continue to serve private individuals, charter companies, training organizations, and government agencies around the world.

Our as355 gen fam course online takes you inside this twin-engine pioneer. You will explore the airframe, the twin Allison 250-C20F or Turbomeca Arrius engines, the four-blade Starflex main rotor system, and the systems that make the AS355 unique, from the combining gearbox that integrates power from both engines to the fuel system and avionics

This AS355 general familiarization course is aligned with FAA ACS (Airman Certification Standards), EASA Part-66 standards, and ATA-104 compliance requirements. Whether you are a mechanic maintaining an AS355 fleet, an engineer preparing for type rating, a pilot transitioning to rotary wing, or simply looking to expand your expertise, this course gives you the foundation you need.

The AS355 proved that a twin-engine light helicopter could offer the same versatility as its single-engine sibling, with the added safety and performance of a second powerplant. Mastering its systems is the key to keeping it flying safely.

Ready to master the TwinStar? Reach out to us to learn more about our Eurocopter AS355 TwinStar systems training.