Aircraft in service are forecasted to double next 20 years with approximately 30,000 new aircraft. To minimise their environment impact a sustained improvement in the efficiency of gas turbine engines is required. For aerospace, the Advisory Council on Aeronautics Research and Innovation in Europe (ACARE), has defined long term challenging competitiveness and environmental goals for the aviation industry. This, together with the airline operators’ requirement for extended time periods between overhauls, requires the introduction of step change technologies. As engine cycles move to lower specific thrust to reduce fuel burn and CO2, fans tend to become larger for a given thrust and therefore the fan system’s weight must be reduced or else the fuel burn advantage is lost. This programme is aimed at introducing a carbon fibre composite fan system on to next generation Rolls-Royce engines. As a lightweight material with high resistance to fatigue, carbon fibre reinforced organic matrix composites provide significant potential for reducing the weight of major components in the gas turbine engine and increasing their operating life when used in applications prone to vibration. A reduced weight saves energy and fuel and consequently reduces emissions. This programme includes design and tooling for the next generation composite fan system aimed at meeting future large engine market. It also includes mechanical and environmental testing to validate such designs.