A combination of a gas turbine engine and power electronics, includes an engine core and oil circuit to cool and lubricate bearings of the engine core, and a fuel circuit for supplying fuel to the combustor. The fuel circuit includes a low pressure pump for pressurising the fuel to a low pressure, and a high pressure pump to receive the low pressure fuel and increase the pressure to a high pressure for supply to a fuel metering system and the combustor. The engine includes a fuel-oil heat exchanger having a fuel side on the fuel circuit between an outlet of the low pressure pump and an inlet of the high pressure pump, and an oil side on the oil circuit to transfer heat from the oil circuit to the fuel circuit. The power electronics transfers heat to a cooling flow formed by a portion of the low pressure fuel.