Hybrid Heir

The BK117 helicopter was ahead of its time, but failed to sell as well as expected. Can its EC145 derivative, with improved payload and performance, do better?

Eurocopter's BK117 was once considered too big for the para-public market. Demands for increased payload have brought the twin-turbine helicopter back into fashion, but revamped as the upgraded EC145. Initial customers for the EC145, law-enforcement agencies and air medical operators, praise the improved helicopter's payload and performance.

With its rear clamshell doors and easy accessibility, the EC145 is heir to the heritage of German dependability, a reputation built up by the MBB-designed BO105 light twin and the larger BK117, which were developed jointly with Japan's Kawasaki Heavy Industries in a 60:40 risk-sharing partnership that continues with the EC145.

Although its heyday was in the 1970s, many of the 1,400 BO105s built are still in public service, a testament to its rugged performance rather than sleek looks. Sales of its larger successor, the BK117, were initially slow. The helicopter first flew in 1979 and received German certification in 1982, but it was not until US approval was gained in 1985 that sales picked up. The emergency medical service market was by then becoming established in the USA and the BK117's bigger cabin, with rear and side loading capability, gave it an edge over other helicopters.

Broadening appeal

With the six- to eight-passenger BK117, MBB hoped to broaden the appeal of its sturdy, bearingless main-rotor helicopters into the lucrative corporate market. Comments by the pilot of a BK117 who used to transport a Middle Eastern VIP around the UK in the late 1980s typify the market's reaction: "Great payload and phenomenal performance, but the rigid rotor transmits any turbulence straight into the cabin. On high skids, it's quite a climb to get in the back too - no good for high heels. More like a Land Rover than a Mercedes sedan."

In the para-public market, meanwhile, the BK117 faced competition from the new generation of light twins, including the MD Helicopters Explorer and Eurocopter's own EC135. Efforts were made to promote the BK117 in the UK for fire service support - "but in the end it was just too big and too expensive", says Nick Kidd, at the time test pilot for UK distributor McAlpine Helicopters. "The smaller MD 900 and EC135, by now starting to arrive on the scene, were cheaper and at the time offered the capacity that emergency services needed."

Despite such setbacks, sales reached respectable levels and the helicopter matured with increased power and payload. As the initial BK117-A1 evolved through the -B1, -2 and -3 into the definitive -C1 model, the helicopter's maximum take-off weight grew from 2,850kg (6,300lb) to 3,350kg, and the Lycoming (now Honeywell) LTS101 engines were replaced by Turbomeca Arriel 1E2s.

When France's civil defence service, the Sécurité Civile, began looking in the mid-1990s for a helicopter to replace its fleet of Eurocopter AS350B Ecureuils, it liked the BK117 but found the cabin slightly too small for its requirement to carry heavily equipped squads. Eurocopter felt that some of the features of the recently launched but smaller EC135 could be incorporated into the BK117 to meet the needs of both the Sécurité Civile and France's Gendarmerie national police service.

The decision was made to mate the EC135's forward fuselage with the rest of the BK117 to create a hybrid known initially as the BK117-C2 and later redesignated the EC145. Ten per cent of the new variant was a "clean sheet" design, involving new rotor blades and a wider, longer cabin with bigger doors, made largely from composites. This expanded the cabin by 20% - accommodating two more passengers - and improved aerodynamics. Composites contribute to the fact that the EC145 can now lift its own weight (empty weight and payload are each 1,790kg), equipped with the same Turbomeca Arriel 1E2 engines.

Successful fusion

"In effect, the Sécurité Civile bought a paper helicopter," says programme manager Manfred Merk, "and we undertook to meet a renegotiated delivery date." The size of the order - 32 for the Sécurité Civile, later supplemented by eight for the Gendarmerie - made the programme worthwhile, but the tight timescale meant the upgrade was limited in scope.

"For example, we retained the BK's conventional tail rotor," Merk says. "If we had put a safer Fenestron on, we would also have had to redesign the tail boom and main gearbox. As it turned out, after we adapted the BK's landing gear to route underneath - as it does in the EC135 - rather than through the fuselage, the clearance below the tail rotor increased to 1.8m [5.8ft], thus adding to safety in another way." The other major improvements were the glass cockpit and full-authority digital engine control.The Gendarmerie's 50 para-military helicopters are operated predominantly on police duties outside major cities, and on rescue missions in mountainous areas (the Sécurité Civile specialises in rescues elsewhere and the Police Nationale handles urban law enforcement). "The EC145s arrived between November 2002 and September last year, as part of a replacement programme for our Alouette 3s," says Commandant Francois Moallic, chief training captain at the Gendarmerie's air wing headquarters at Villacoublay, near Paris. "They have settled in very well, although flying with the rigid rotor head required some practice for our crews - especially during sloping-ground landings, which demand a different technique. The mast moment indicator becomes an important part of the instrument scan."

Both training and power paid off last year, when a Gendarmerie EC145 with five people aboard landed on top of Mont Blanc, an altitude of 15,700ft. The EC145s have partially replaced a fleet of eight Alouette 3s. Pleased with the new helicopter's performance, the service may buy more of them, says Moallic. "We need another seven helicopters and will make a decision on type during the summer."

Many BK117s operate offshore in Indonesia, Italy and the USA. "We are only now starting to target the EC145 at sectors such as this," says Merk. "It is a multipurpose helicopter and has features that are attractive to several types of user. Together with Kawasaki, we have sold about 430 BK117s to 145 operators around the world and we expect the EC145 to have an impact in the same areas."

In its Asian "patch", Kawasaki has achieved sales of about 130 BK117/EC145s, mainly for use offshore and in the highly active electronic news-gathering role. Five EC145s are in service in Japan, where air regulations restrict para-public operations - helicopters, for example, can fly over an accident site and film it for a TV network but not land to help.

North American orders

The first of five EC145s ordered by North American customers was delivered to Florida's Lee County emergency medical services in March, and went straight into service. The EC145 joined a BO105 that has been in operation with Lee County since 1990, and which will continue to serve as a back-up aircraft in its life support and search-and-rescue operations.

"Our Bolkow [BO105] has met the county's needs for years," says Lee County chief pilot Rick O'Neal. "The EC145 offers us many operational advantages, including a larger cabin and the ability to accommodate additional equipment." Lee County emergency medical services supports a region of Florida where the population more than doubles during the winter, and which is bordered by 75 barrier islands in the Gulf of Mexico - a lot of them with no road access to the mainland. Aircraft completion was carried out by Metro Aviation at Shreveport, Louisiana.

Like its BO105 predecessor, the original BK117 continues to give good service. One aircraft, with over 10,000 airframe hours on the clock and recently refurbished by Texan completion centre Heli-Dyne, is thought to be the oldest surviving production model. The helicopter saw 20 years service with the Medstar air medical services (AMS) programme at Washington DC before being cycled into operator CJ Systems' back-up fleet.

Heli-Dyne then performed a complete interior refurbishment, avionics upgrade and paint job, the aircraft even receiving a new tail number. "When that BK117 left here, it was a piece of machinery that any AMS operator would love to have," says Heli-Dyne president David Horton. "It's every bit as good - if not better - than some of the newer aircraft that service the industry today." CJ Systems has since placed the aircraft back into full-time AMS service with Baptist LifeFlight in Mobile, Alabama.

UK police niche?

David Lewis, sales director for distributor McAlpine, believes the EC145 will find a niche within UK police aviation, but as much for its passenger capacity as its equipment payload. "The EC135 is ideal as a surveillance aircraft but, like the Gendarmerie, there is often a need for UK police forces to carry teams of various specialisations, and the two extra seats in the EC145 can be very useful. I see one type as complementing the other - but with the larger one operated perhaps as a shared resource."

When the BK117 entered service, there was limited demand for the payload capability the helicopter offers. "Nowadays though, such is the amount of mission equipment that para-public helicopters want to carry that the type is coming back into fashion," says Kidd. "[The EC145] may stretch some budgets, but it can give you 1,300kg of payload coming out of a helipad, and that is attractive to any public service operator."

ANDREW HEALEY / LONDON

Source: Flight International