According to long-term predictions in helicopter market development made by the US National Research Council subcommittee and the largest corporations AlliedSignal and Rolls-Royce, two-engine gas turbine helicopters are going to lead as to the number of orders and sales volumes more and more confidently now.
Relevant necessity
Today they hold a confident second position in this respect, giving way to single-engine aircraft, which is quite easily explained by the price difference.
The basic factors that define steady demand for this type of aircraft are economic growth in the most of the world’s regions, lots of outdated helicopters, especially in Europe, and the emergence of new models. The reasons for buying new aircraft are as follows: the need to improve flight and technical performance, mostly speed; size, comfort and improvements in cabin configuration; as well as the increase of carrying capacity (payload).
Other important factors causing the demand for two-engine helicopters are the new limitations of helicopter flying over built-in areas. And, finally, two engines mean that you can be sure of your safety and the needed power supply in case one of the engines’ malfunction, which is especially important at takeoff, during the hovering regime and when working with external load.
Today we’ll speak about top models belonging to the medium class, certified for safety class A (the highest category).
Eurocopter
Let’s turn our eye to Europe first and see what kind of rotary-wing machines of the medium class are offered to potential customers by the Old World manufacturers. The undoubted leader is the French Eurocopter, a monster of European helicopter construction, with one of their latest developments, a multipurpose ЕС 155 B1.
ЕС 155 B1 is a two-engine helicopter, the newest in the Dolphin family. First industrial series was launched in March 1999. This machine is different from any other because it uses such new-generation technologies as Spheriflex type five bladed rotor head and Fenestron type tail rotor.
ЕС 155 B1 has one of the lowest levels of external noise and cabin vibration in its category. It is equipped with the latest-generation autopilot, integrated control panel (MEGHAS) and digital control system for both engines (FADEC). Depending on the specifications, the cabin holds 5 to 12 passengers. The crew consists of 2 people.
The helicopter is equipped with two 780 kilowatt/1046 hp Turbomeca Arriel 2C2 engines. Its cruising speed is 265 kmph, range is 909 km. Maximum takeoff weight equals 4,850 kg. The helicopter can be operated at a temperature range from – 40 to + 50 °С.
Incidentally, ЕС 155 В1 is considered one of the most appropriate for VIP passenger travel, which was proven at the European E.B.A.C.E fair that took place in the end of May.
Agusta Westland
Another and just as interesting medium-class helicopter is AW 139 by the Italian Agusta Westland.
This multi-purpose helicopter designed for a wide range of tasks flies at a speed of 310 kmph and has a payload of 2,778 kg. It is a combination of all the newest technologies and company’s developments. 
Flying AW 139 is smooth and comfortable, and controlling it is no harder than a light business jet or a school bus.
Another nice feature is excellent visibility from the pilot’s seat: the field of view from large windows is perfect. The helicopter is equipped with the new Honeywell piloting system. Four large 20x25-cm portrait (full page vertical) displays allow the crew to choose the viewing regime, including combined working regimes. The central control console located between the pilots’ seats is equipped with fuel rate control system, as well as launch and engine control systems.
Two 1679-hp Pratt & Whitney PT6C-67C engines are located in separate fireproof modules.
The passenger cabin houses 12 passengers in specification with a longer range (for instance, for working at sea platforms), or a maximum of 15 passengers plus 2 pilot seats. Maintenance costs are around $800 an hour.
The helicopter features shockproof technology at emergency landing and retracting landing gear. It’s one of the most advanced and efficient helicopters to date.
Bell Helicopter Textron Company
American manufacturers have traditionally led the helicopter market, as the aircraft construction industry developed. And perhaps, as far as manufacturing of gas turbine machines goes, the first violin is played by Bell Helicopter Textron Company. While Bell 430, a two-engine multipurpose helicopter, is number one in the class we’re talking about.
A two-engine system (Rolls-Royce 250-C40B), new technologies, excellent vibration-proof and durability characteristics guarantee maximum safety to the passengers of the aicraft. Due to hi-tech construction of the main rotor Bell 430’s flight performance can be compared to that of the fixed-wing aircraft: smooth flying at a speed (250 kmph) and high carrying capacity.
Providing comfort and aesthetics was the main aim of hull designers, who succeeded in achieving it. The hull of Bell 430 has become a new standard in noise reduction and durability.
The elegant construction is reinforced by the helicopter’s striking design. A lengthened passenger cabin is spacious enough and comfortably seats 8. A big number of passenger cabin options allows to meet the requirements of even the most demanding customers. Bell 430 is a fine, reliable, sturdy and durable helicopter.
Sikorsky United Technologies
Sikorsky owns their leadership in the segment of two-engine gas turbine helicopters to S-76C+, the updated S-76.
Besides being steady and sturdy in flight, S-76C+ is equipped with a fully self-regulating electronic engine control system (FADEC), which facilitates engine control, decreases fuel consumption, increases power and at the same time facilitates the piloting process. These improvements allow an S-76C+, which is certified for single pilot, to work in poor weather conditions day and night. Heated cabin windows and double screen wipers allow fine visibility for the pilots even in bad weather. Due to the two Turbomeca Arriel 2S1 engines the cruising speed of the helicopter is 286 kmph, while its practical range is over 640 km.
A business-class Sikorsky S-76C+ features 6 passenger seats, including 2 folding leather seats. The interior is all expensive upholstery and handmade wooden panelling. On client’s wish the cabin which is approximately 2,5x1,8 m can be reequipped for 13 passengers, however, the comfort levels will therefore decrease.
Apart from everything else, the key assets of S-76C+ are safety and reliability. No other commercial plane has flown so many hours (around 3 million) without breakage.
Dmitry Gnatenko
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