Eurocopter EC135
The Airbus Helicopters H135 is a twin-engine civil light utility helicopter produced by Airbus Helicopters. It is capable of flight under instrument flight rules and is outfitted with a digital automatic flight control system. First flying in February 1994 and developed from the prototype Messerschmitt-Bölkow-Blohm Bo 108, it entered service in 1996. 1,400 units have been delivered up to September 2020, to 300 operators in 60 countries, accumulating over 5 million flight hours. It is mainly used for air medical transport, corporate transport, law enforcement, offshore wind support, and military flight training. Half of the units in service are in Europe and a quarter in North America. The H135M, certified under the name Eurocopter EC635, is a military variant, so the overall design is known as the Airbus Helicopters H135 and the military version, as the Airbus Helicopters H135M.
Development
Origins
The H135 started development prior to the formation of Eurocopter, under Messerschmitt-Bölkow-Blohm under the designation Bo 108 in the 1970s. MBB developed it in partnership with Aérospatiale, the Bo 108 was initially intended to be a technology demonstrator, combining attributes of the successful MBB Bo 105 with new advances and an aerodynamically streamlined design. Technologies included on the Bo 108 included the first full-authority digital engine controls on a helicopter, a hingeless main rotor, and the adoption of a new transmission. The first prototype made its first flight on 17 October 1988, powered by two Allison 250-C20R/1 engines. A second Bo 108 followed in June 1991, this time with two Turbomeca TM319-1B Arrius engines. Unlike later production aircraft, both technology demonstrators flew with conventional tail rotors.In the late 1990s, the design was revised with the introduction of the Fenestron tail rotor system, an advanced rigid main rotor, composite materials, and resonance isolation systems. It was decided to pursue a full certification program, resulting in the production of two pre-production prototypes. At the same time, the Bo 108 was given a new designation of EC135, to correspond with the newly created Eurocopter company. At this point, it was decided that the EC135 should be developed with the option of being powered by two competing engines, the Turbomeca Arrius 2B and the Pratt & Whitney Canada PW206B engines. Two pre-production prototypes were built in 1994 powered by either engine, both powerplants proved to be successful and were used on subsequent production aircraft.
In January 1995, the EC135 made its first public appearance at the Heli-Expo convention at Las Vegas, at which prospective buyers were reportedly impressed with its appearance and performance figures. Another feature which became apparent upon entering service was the low noise levels produced, in part due to its Fenestron tail, the EC135 was the quietest aircraft in its class for more than 15 years. Despite the helicopter's design being primarily oriented towards emergency medical operators, the EC135 had considerable appeal to a wide range of operators. European JAA certification was achieved in June 1996, with FAA approval following in July.
In December 1999, the EC135 was granted single-pilot instrument flight rules certification by Germany's Luftfahrt-Bundesamt. In December 2000, the United Kingdom's Civil Aviation Authority also gave the EC135 single-pilot instrument flight rules certification.
Further development
In 2000, Eurocopter announced the start of certification work on the EC135P2, powered by the Pratt & Whitney Canada PW206B2, offering improved single-engine performance and 30-second emergency power. The Luftfahrt-Bundesamt certification was achieved in July 2001, and the first EC135 with the new engines was handed over to the Swedish Police Authority in August 2001. In September 2002, the EC135T2 equipped with the improved Turbomeca Arrius 2B2 was made available, providing for improved single-engine performance.In 2002, the EC135 active control technology demonstrator/flying helicopter simulator, a research aircraft designed to test fibre optic-based flight control systems, undertook its first flight. In 2014, Airbus Helicopters began flying the Bluecopter demonstrator aircraft, built to explore more efficient design elements, including economy-optimised single-engine operations, Blue Edge swept rotor blades to reduce noise and increase efficiency, a relocated horizontal stabiliser outside the main rotor's downwash, an active rudder, and new water-based external paint; these changes were aimed at cutting fuel consumption by 40%. In December 2014, the single-engine operations portion of the Bluecopter tests were delayed to summer 2016 to make necessary avionics changes, such as to the engine's FADEC systems.
In March 2007, at the NBAA in Atlanta, Eurocopter unveiled 'L'Hélicoptère par Hermès, a special-edition VIP model designed by Hermès International, S.A. It features a customised luxury four-place main cabin, a sliding glass partition, a corporate baggage hold, redesigned skid landing gear and other external changes. The launch customer for the type is Falcon Aviation Services, based in Abu Dhabi, United Arab Emirates. In July 2014, Airbus Helicopters made further personalisation options available for the EC135 l'Helicoptere par Hermes.
In 2011, Eurocopter formalised a licence manufacturing agreement with Zhong-Ou International Group to produce the EC135 luxury helicopter in Zhejiang Province, China. In October 2015, a letter of intent between Airbus Helicopters and Ecopark was signed for the establishment of a final assembly line in Qingdao Province, China. A related $1.1 billion order for 100 Chinese-assembled H135s was announced in the same month. The majority of assembly work on the type remains at Airbus Helicopter's Donauwörth facility. Construction of the FAL started in May 2017, and opened for production in April 2019.
In January 2016, the Ural Works of Civil Aviation, a division of Rostec, signed an agreement to build the H135 under licence at the firm's facility in Yekaterinburg, Russia. In May 2016, it was reported that Russian production of the H135 was anticipated to begin in 2017, following the receipt of Russian type certification. Russian manufacturers may be incorporated in the global supply chain.
Two variants, the EC135 T3 and EC135 P3, were developed with improved high altitude and hover performance. Changes include repositioned air intakes to the engines, wider blades being installed on the main rotor, and changes to the fenstron anti-torque tail device. The EC135 T3 was introduced to service in December 2014.
In December 2020, the H135 helicopter family EASA has certified a new Alternate Gross Weight. With the new AGW, the maximum takeoff weight has been increased up to 265 lb and payload. This modification can be used to increase range by up to 75 nm or endurance by up to 40 minutes under standard conditions. The new AGW is available as an option and can be applied retroactively to all Helionix-equipped H135s.
In December 2020, Airbus certified a new single-pilot instrument flight rules Helionix cockpit for its H135 helicopters. The modified cockpit allows customers to choose whether to remove the copilot side of the instrument panel to increase the field of view or keep it to install specific STC equipment.
Design
The H135 is a twin-engine rotorcraft. It can be alternatively powered by a pair of Turbomeca Arrius 2B or Pratt & Whitney Canada PW206B engines, dependent on customer's preference, which gives either a T or a P, respectively, in the variant name. The main rotor is of a four-bladed, hingeless fibre-composite design. Progressive improvements to the main rotor have increased its performance and reduced maintenance costs since the type's introduction. The EC135 is the quietest helicopter in its class, featuring an anti-resonance isolation system to dampen vibration from the main rotor. The type's Fenestron anti-torque device can be actively regulated via a HI NR rotor optimisation mode, which provides for greater controllability during higher weight take-off and landings. It is capable of performing Category A operations throughout its full flight envelope.The EC135 can be equipped with either a conventional flight deck or the Avionique Novelle glass cockpit – the latter allows for single pilot instrument flight rules operation. The glass cockpit is equipped with several liquid-crystal displays, including two Sextant SMD45 displays and a central panel display. The main avionics suite is supplied by Thales Group. The EC135 can be outfitted with various avionics suites from manufacturers such as Russian firm Transas Aviation and British firm Britannia 2000.
The newer H135 model can be equipped with a four-axis autopilot, which is included as part of the Helionix avionics suite. This suite provides the H135 with a greater level of commonality with several other Airbus Helicopters-produced rotorcraft, including the H145, H160 and H175. Earlier versions of the EC135 were equipped with a three-axis autopilot with integrated stability augmentation, featuring a First Limit Indicator, simplifying engine and torque monitoring. Cockpit touch screens can be optionally installed.
Various cabin and cockpit configurations are available for the EC135, depending on the role performed and the operator's preferences. It can hold up to five passengers and a pilot when configured with a standard executive interior, or seven passengers in a dense corporate interior. Modular multi-role interiors that allow the main cabin area to be quickly changed and re-equipped are available. The main cabin of the EC135 is accessed either by large doors on either side of the cabin or by clamshell doors located at the rear of the cabin, directly underneath the aircraft's tail boom. The clamshell doors are particularly attractive to emergency medical services and cargo operators.
Medical facilities can be installed in the cabin, such as in-flight intensive care stations, incubators, and hygiene-convenient flooring. In a mountain rescue configuration, the cabin can simultaneously accommodate two stretchers as well as the pilot, anaesthetist, winch operator, mechanic and mountain rescue specialist.
Airbus Helicopters has promoted the airframe's various configurations as possessing "unique adaptability" for various missions, including utility work, commercial transportation, and training roles. Equipment for the law enforcement role include external loudspeakers, rappelling system, search lights with laser pointers, left or right-mounted hoists, and electro-optical sensors. For offshore oil & gas operations, the rotorcraft can be fitted with weather/search radars, emergency floatation aids, including an automated external life raft, energy-absorbent seating, class-D certified external hoists, and crash-resistant fuel tanks. An external hook can be installed to carry underslung loads of up to 272 kg for cargo missions. In a training capacity, features such a light aircraft recording system for post-flight analysis, intuitive human-machine interface, specific training modules, and a one-engine inoperative training mode, and full ground simulators, may be selected.