The imagination and ingenuity of owners and operators constantly adds new business scope to the already diverse roles of rotary aircraft in general and twin engine helicopters in particular. The type range of 'twins' used by operators is impressive, with the S-76, Super Puma and EC135 just three of dozens of varieties built by Western manufacturers. Russian models include the Mi-171, the result of intense modernisation of the Mi-8, a model that has racked up more than 100 million hours.

The result is a polyglot of types that are used in many roles at the forefront of technology ranging from wind farms to major health projects as well as traditional roles such as vip charter and offshore transport.

An EC135, operated by Bond Air Services, is the chosen aircraft to deliver personnel and complex equipment by winch at the Greater Gabbard wind farm off the UK's East Anglian coast. Another trailblazing role for helicopters is being defined in France. Eurocopter, the hospital in Dreux, the French association of helicopter emergency medical services and the French civil aviation authority have cooperated in a series of instrument flight tests. Positive results are expected to enable patients to be transported by helicopter from one hospital to another even under poor weather conditions.

In the UK, PremiAir's newest charter helicopter is a "beautifully presented" 2009 Sikorsky S76C++. David McRobert, the group's md says: "The aircraft has a six seat vvip cabin featuring Sikorsky's latest 'Silencer' interior which delivers cabin noise levels approaching that of business jets."

He adds: "It really is a fantastic helicopter. Since it entered service in May it has been in strong demand from regular and new customers. Feedback has been excellent and we're delighted to have it."

PremiAir is among more than 200 operators in 37 countries flying S-76s for missions including corporate and vip charter, emergency medical service, search and rescue, offshore oil crew transport and civil defence.

Peter Kolesnik, director-pilot of Switzerland's Linth Air Service, does not feel the S-76 needs any upgrades. The company, which has used the aircraft for passenger charter since 2005, says it is happy with the maintenance arrangements, availability of spare parts, dispatch rate and value.

Stephen Tierney of the UK's Air Harrods, which owns three of its own helicopters and operates them for charter with Capital Air Services, also manages an A109 and an S-92 which are also available for charter.

Tierney says: "The S-76 has a superb cabin with plenty of room and very easy access. It is a fast aircraft with smooth and comfortable level ride. The latest C++ version has enhanced performance with Turbomeca Arriel 2S2 engines with increased single engine power over other C models. These engines are among the most fuel efficient helicopter engines currently available on the market." Tierney says that both the company's S-76s are fitted with the Sikorsky 'quiet' technology main gearbox. "These have made a big difference in reducing cabin noise, added to which we have the latest silencer interior fitted which, although lighter in weight than previous vip interiors, has far superior sound proofing. Our cabins do not require headsets for passengers to talk with one another."

VIP transportation and corporate charter is the main role of the 76s that Air Harrods owns and operates.

Tierney says: "We have our own highly experienced engineer and a maintenance contract with HAL which is Part 145 approved for the S76 and S92. We have no need to look elsewhere. We have an excellent dispatch rate and having new aircraft helps with reduced maintenance costs and also spares acquisition. We enjoy excellent support from Sikorsky's HSI."

The latest and most advanced model, the S-76DTM, is scheduled to enter production in 2010. PremiAir's helicopters range in size from AS355 Twin Squirrel to Sikorsky S-92, with four Sikorsky S-76s among company aircraft are based close to London. David McRobert says: "All PremiAir's fleet are IFR aircraft, flown by highly experienced instrument rated pilots."

He says: "The recession has not been easy for business aviation but I'm glad PremiAir took the opportunity in the past to diversify its operations into many areas of executive helicopter and business jet services, so helping to protect our overall business from the significant swings certain markets have witnessed."

PremiAir's maintenance business is centred on Blackbushe airport near Farnborough. "For over 25 years we've been well known as Sikorsky S-76 and Bell 222/430 specialists, but now we offer a full range of services on many different helicopter types," says Barry Stone, PremiAir's engineering director. "Our focus is on providing high quality maintenance and FBO services for all executive helicopter owners and operators. Over the last five years we have seen our maintenance business grow to include the AS365 and EC155, A109 and Grand and during the last year the Sikorsky S92."

PremiAir Global, PremiAir's aircraft sales and acquisition business, has seen very tough market conditions over the last year. But Tim Blockley, PremiAir Global's md, believes that the most difficult trading conditions "are now behind us."

Erlend Folstad, commercial manager of Norway's Airlift, says: "We have operated the Super Puma since 1996 and we are very satisfied with the helicopter type."

Airlift has two Super Pumas, one an Awsar AS 332 L1 which is a SAR helicopter on Spitsbergen. "This helicopter is maybe operating in one of the hardest environments in the world," says Folstad. "It is fully de-iced and has NVIS."

The other, an AS332C, is a heavy lifter. "With this we performed the longest helicopter rescue ever performed. It involved flying 600 nm from Spitsbergen to North Greenland including 400 nm over open sea crossing from Spitsbergen to Greenland and and then back again in one flight." The rescue operation saved the life of a scientist.

As well as roles ranging from wind farm maintenance to vip charter, twin-engined helicopters are vital in the offshore industry. Bristow Helicopters, which has won a new contract to supply shuttle services between the Safe Caledonia flotel and the Franklin platform in the central North Sea, is operating morning and evening shuttles using an offshore-based AS332L for Total E&P UK Ltd. Bristow also operates the S-92 which competes in a market sector where the Super Puma is also prominent.