Improvement in fuel efficiency in aeroengines is a constant goal of aeroengine manufacturers since fuel represents a large part of the operating costs of an aircraft and is responsible for the greenhouse gases emitted by an aircraft.The Dual Drive Booster (DDB) is a novel concept applicable to two shaft aeroengines that has the potential to reduce the fuel burn.The concept has been recognised as novel and feasible with the granting of a patent in September 2015 (Patent No. GB2513621B). A fuel burn benefit of around 2% has been verified by engine performance modelling at Aachen University.In a conventional 2-shaft aero-engine, the booster compressor is directltly driven by the Low Pressure shaft which limits its rotational speed. In a Dual Drive Booster (DDB) engine, the booster compressor is driven through an epicyclic gearbox by both the Low and High pressure shafts. This increases the rotational speed of the booster compressor and so improves its efficiency along with other engine cycle benefits. The epicyclic gearbox has been shown by preliminary analysis to be technically feasible but a number of risks have been identified. Because the gearbox opperates at high speed, there is a risk of high heat generation due to oil churning. The project is to create a computer model of the gearbox to simulate the oil and air flows so that the design can be optimised to reduce the heat generation to a minimum. The stress levels in the gears will also be checked.