A method for operating a hybrid electric aircraft propulsion system, the method comprising: providing a first electric propulsor and a second electric propulsor with a first source of propulsion power from a generator configured for generating an output of alternating current electric power; providing the first electric propulsor and the second electric propulsor with a second source of propulsion power from at least one motor inverter (208A,208B;308) operatively coupled to a direct current power source, the at least one motor inverter (208A,208B;308) configured to convert the DC electric power from the DC power source into a second source of AC electric power; and modulating the second source of AC electric power applied to the first electric propulsor or the second electric propulsor from the at least one motor inverter (208A,208B;308) to synchronize the frequency of the first electric propulsor or the second electric propulsor with the frequency of the generator, characterised by: providing the first source of propulsion power to the first electric propulsor from the generator via a first motor stator of a first electric motor; providing the first source of propulsion power to the second electric propulsor from the generator via a first motor stator of a second electric motor; providing the second source of propulsion power to the first electric propulsor from the at least one motor inverter (208A,208B;308) via a second motor stator of the first electric motor; and providing the second source of propulsion power to the second electric propulsor from the at least one motor inverter (208A,208B;308) via a second motor stator of the second electric motor, such that the first source of propulsion power from the generator is independent of the second source of propulsion power from the at least one motor inverter (208A,208B;308). providing a first electric propulsor and a second electric propulsor with a first source of propulsion power from a generator configured for generating an output of alternating current electric power; providing the first electric propulsor and the second electric propulsor with a second source of propulsion power from at least one motor inverter (208A,208B;308) operatively coupled to a direct current power source, the at least one motor inverter (208A,208B;308) configured to convert the DC electric power from the DC power source into a second source of AC electric power; and modulating the second source of AC electric power applied to the first electric propulsor or the second electric propulsor from the at least one motor inverter (208A,208B;308) to synchronize the frequency of the first electric propulsor or the second electric propulsor with the frequency of the generator, providing the first source of propulsion power to the first electric propulsor from the generator via a first motor stator of a first electric motor; providing the first source of propulsion power to the second electric propulsor from the generator via a first motor stator of a second electric motor; providing the second source of propulsion power to the first electric propulsor from the at least one motor inverter (208A,208B;308) via a second motor stator of the first electric motor; and providing the second source of propulsion power to the second electric propulsor from the at least one motor inverter (208A,208B;308) via a second motor stator of the second electric motor, such that the first source of propulsion power from the generator is independent of the second source of propulsion power from the at least one motor inverter (208A,208B;308).