A method of operating an aircraft power and propulsion system, the power and propulsion system comprising one or more propulsive gas turbine engines (110; 110a, 110b), each engine comprising a plurality of spools (16, 19, 26; 15, 17, 27) including a first spool and a second spool, a first electric machine mechanically coupled with the first spool and a second electric machine mechanically coupled with the second spool, wherein each of the first and second electric machines (111, 112) of each of the one or more gas turbine engines comprises a first sub-machine (111', 112') and a second sub-machine (111", 112"); and an electrical system connected with the electric machines and comprising an electrical energy storage system, the method comprising: operating one or more of the electric machines (111, 112) of the one or more gas turbine engines (110; 110a, 110b) as generators to extract, for each of the one or more gas turbine engines, greater than 5% of a combined mechanical power of the plurality of the spools (16, 19, 26; 15, 17, 27) and to generate electrical power therefrom; meeting an electrical power demand, P D, of a plurality of electrical loads (115, 116, 150) connected with the electrical system by supplying the plurality of electrical loads with electrical power generated by the one or more electric machines (111, 112); determining a condition to the effect that there is a fault in one or more of the electric machines and that an amount of electrical power being generated by the power and propulsion system has reduced to a lower level, P fault; and responsive to the determination: during a time period ΔT, meeting (361, 371) at least part of the electrical power demand of the plurality of electrical loads (115, 116, 150) by discharging the electrical energy storage system; and during the time period ΔT, controlling the plurality of electrical loads (115, 116, 150) to reduce the electrical power demand. operating one or more of the electric machines (111, 112) of the one or more gas turbine engines (110; 110a, 110b) as generators to extract, for each of the one or more gas turbine engines, greater than 5% of a combined mechanical power of the plurality of the spools (16, 19, 26; 15, 17, 27) and to generate electrical power therefrom; meeting an electrical power demand, P D, of a plurality of electrical loads (115, 116, 150) connected with the electrical system by supplying the plurality of electrical loads with electrical power generated by the one or more electric machines (111, 112); determining a condition to the effect that there is a fault in one or more of the electric machines and that an amount of electrical power being generated by the power and propulsion system has reduced to a lower level, P fault; and responsive to the determination: during a time period ΔT, meeting (361, 371) at least part of the electrical power demand of the plurality of electrical loads (115, 116, 150) by discharging the electrical energy storage system; and during the time period ΔT, controlling the plurality of electrical loads (115, 116, 150) to reduce the electrical power demand. during a time period ΔT, meeting (361, 371) at least part of the electrical power demand of the plurality of electrical loads (115, 116, 150) by discharging the electrical energy storage system; and during the time period ΔT, controlling the plurality of electrical loads (115, 116, 150) to reduce the electrical power demand.