An aircraft comprising a gas turbine main engine and an electrical network, the electrical network comprising: a first starter generator mechanically coupled to a first shaft of the main engine and a further starter generator mechanically coupled to a further shaft of the aircraft main engine, the first starter generator being configured to turn the first shaft of the main engine when operated in a starting mode, and to generate electricity from the first shaft of the gas turbine engine when operated in a generating mode; a DC electrical bus electrically coupled to one or more electrical loads; an engine AC electrical bus comprising one or more engine electrical loads and an aircraft AC electrical bus comprising one or more aircraft electrical loads, the engine AC bus being electrically coupled to the first starter generator and further starter generator, and the aircraft AC electrical bus being electrically coupled to the first starter generator; wherein the DC electrical bus is electrically coupled to the AC electrical buses (56, 58) via a bi-directional AC / DC converter, and wherein; the bi-directional AC / DC converter is configured to provide AC electrical power from the DC electrical bus to power the first starter generator when the first starter generator is in a starting mode, and DC electrical power to the DC electrical bus when the first starter generator is in a generating mode; and wherein the aircraft comprises a network controller configured to moderate the amount of electrical power provided to the electrical loads from each of the first starter generator and the further starter generator, and to moderate the amount of power provided to at least the first starter generator from the DC electrical bus, the network controller being configured to operate the electrical network in a first generating mode, in which the further starter generator provides all electrical power required by the main engine electrical loads and the first starter generator provides all electrical power required by the aircraft electrical loads and a second generating mode, in which the further starter generator provides part of the electrical power required by both the aircraft and engine electrical loads and the first starter generator provides the balance of electrical power required by the aircraft electrical loads. a first starter generator mechanically coupled to a first shaft of the main engine and a further starter generator mechanically coupled to a further shaft of the aircraft main engine, the first starter generator being configured to turn the first shaft of the main engine when operated in a starting mode, and to generate electricity from the first shaft of the gas turbine engine when operated in a generating mode; a DC electrical bus electrically coupled to one or more electrical loads; an engine AC electrical bus comprising one or more engine electrical loads and an aircraft AC electrical bus comprising one or more aircraft electrical loads, the engine AC bus being electrically coupled to the first starter generator and further starter generator, and the aircraft AC electrical bus being electrically coupled to the first starter generator; wherein the DC electrical bus is electrically coupled to the AC electrical buses (56, 58) via a bi-directional AC / DC converter, and wherein; the bi-directional AC / DC converter is configured to provide AC electrical power from the DC electrical bus to power the first starter generator when the first starter generator is in a starting mode, and DC electrical power to the DC electrical bus when the first starter generator is in a generating mode; and wherein the aircraft comprises a network controller configured to moderate the amount of electrical power provided to the electrical loads from each of the first starter generator and the further starter generator, and to moderate the amount of power provided to at least the first starter generator from the DC electrical bus, the network controller being configured to operate the electrical network in a first generating mode, in which the further starter generator provides all electrical power required by the main engine electrical loads and the first starter generator provides all electrical power required by the aircraft electrical loads and a second generating mode, in which the further starter generator provides part of the electrical power required by both the aircraft and engine electrical loads and the first starter generator provides the balance of electrical power required by the aircraft electrical loads.