Airbus Helicopters H135M (EC635)

History of Airbus Helicopters H135M (EC635)

Airbus Helicopters' H135M is the military market version of its successful H135 light utility helicopter product. The H135 was born in the 1970s as "Bo 108" under the Messerschmitt-Bolkow-Blohm (MBB) brand label (backed by the French Aerospatiale).

A twin-engine layout (digitally controlled by FADEC) was chosen, inheriting features from the previous Bo 105 helicopter, and a prototype with a traditional open tail rotor unit made its maiden flight on 17 October 1988. The Bo 108 was originally intended as a technology demonstrator, but its evolution means it has become so much more.

In the second half of the 1990s, the Fenestron tail was installed and more composite designs were introduced. Two pre-production prototypes followed, and the MBB now bears the Eurocopter branding, which comes in the form of "EC135". The helicopter made another maiden flight on February 15, 1994, and the design was publicly demonstrated in January 1995.

After type approval, it entered service in 1996 and has been in production since 1995. Over 1,220 units have been produced to date (2017) with global operators covering both military and civilian markets. In the first case, the product became EC635, which entered service in May 1998.

With the introduction of Airbus Helicopters, the EC135 product became "H135" and the EC635 became "H135M".

Like the H135 before it, the H135M relies on a fixed four-point landing gear and is equipped with a fenestron ducted tail rotor. The main rotor assembly consists of a low-mounted four-blade system. The windows in the front of the hull are large and provide an excellent view from the cockpit.

The helicopter is operated by a pilot and can accommodate up to eight passengers or two patient stretchers/two auxiliary equipment for medical evacuation missions.

Airbus Helicopters supports the H135's versatility in "hot and hot" environments, an atmospheric condition where air density is low due to high altitude and high ambient temperature. This poses challenges for both aircraft and engines, and deserves the attention of engineers to develop a product that can operate in such an environment. With such qualities, the H135 has become one of Airbus Helicopters' most popular products and certainly one of the most popular light commercial aircraft in service - an aircraft capable of performing various types of missions, both civil and military.

Fenestron tail rotor units also help suppress noise signatures, an important feature to consider in urban operations.

The H135M is powered by 2 Pratt & Whitney Canada PW206B2 turboshaft engines, each producing 817 hp, driving a twin-blade main rotor and a fenestron ducted tail rotor. Performance includes a top speed of 161 mph, a cruising speed of 158 mph and a range of up to 405 miles. The aircraft has a service ceiling of 20,000 feet.

The climb rate is 2,150 feet per minute.

Variants of this series include H135MT1/P2/T2 and H135MP2+/T2+. The former was launched in 2001, while the latter was introduced in 2006 with improvements, including reinforcement.

All models share two engine options - Pratt & Whitney or Turbomeca type - to meet customer/mission performance requirements.

To date (January 2017) there are few military operators of the H135M, including Iraq (Army), Jordan (Air Force) and Switzerland (Air Force).

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