Small gas turbine engines are used in a large variety of applications (Fig. 1) and therefore any model range should accommodate as many of these roles as possible to secure a broad market base. First and second generation engines were launched initially against a requirement for military helicopters and small to medium sized turboprop powered aircraft. However due to the search for oil the role of the helicopter has expanded into offshore oil exploration whilst the better fuel efficiency of the turboprop powered aircraft relative to the turbofan will ensure its future for short range commuter aircraft. Additionally with further improvements in helicopter and engine reliability and costs, the helicopter will be used increasingly in the Air Taxi role to provide rapid transportation over short distances to avoid ground traffic congestion or particular geographical features that preclude short transit times. Specifically the use of the helicopter to connect airports with each other and city centres is becoming a real possibility as reliability improves and operational costs reduce.