Turbine helicopters are used for a wide range of different roles across several industries. They are also fairly frequently reconfigured for executive use, having previously flown a different role. Defined by their turbine engines, Turbine Helicopters are faster and more powerful than piston models. Depending on the size and model, Turbine Helicopters can accommodate anywhere from four in the case of a single-engine turbine helicopter, up to 15 or more passengers in the case of a twin turbine aircraft. They are ideal for owners or operators needing to access locations within a 250-600 distance without a runway. Leading manufacturers in the Turbine Helicopter field include Airbus Helicopters, Bell, Leonardo, Robinson and Sikorsky, while older, popular used models have also been produced by AgustaWestland and Eurocopter.