For an assumed aircraft＇s mission profile (consisting of several Fight stages), using a bespoke computer simulation, the consequences of engine deterioration upon the weight of the fuel that has to be carried and consumed are predicted. This will help in making wiser management decisions (such as whether to remove an aero-engine from the aircraft for maintenance or to continue using it with some changes in the aircraft＇s mission profile). Hence, improved engine-utilisation can be achieved, so resulting in lower overall life-cycle costs,