1. A method of controlling a fuel supply for an aircraft-mounted turbine engine, the method comprising: monitoring a differential oil pressure associated with an operating engine, the differential engine oil pressure determined using signals representing at least two measured operating engine oil pressures, to determine whether a change in the monitored differential engine oil pressure has occurred; upon determining that a change in the monitored differential engine oil pressure has occurred, using signals representing at least one other aircraft or engine operating parameter to determine whether the change in differential engine oil pressure corresponds to a desired change in an output power level for the engine; and if it is determined that the change in differential engine oil pressure does not correspond to a desired change in an output power level for the engine, calculating a desired fuel flow rate for the engine and providing a corresponding command signal to an engine fuel supply controller.