Hybrid electric engine speed regulation

A controller for a gas turbine engine comprising memory and one or more processors, the memory storing instructions that when executed by the one or more processors perform the following control steps:

• control a rotational speed of a shaft at least in part with a fuel flow control circuit operable with a fuel delivery system of the hybrid-electric propulsion engine;
• receive data indicative of an actual rotational speed of the shaft;
• calculate an error between the actual rotational speed of the shaft and a commanded rotation speed of the shaft;
• provide the calculated error to an electric machine control circuit operable with an electric machine of the hybrid-electric propulsion engine, the electric machine drivingly coupled to the shaft;
• and
• modify a torque on the shaft from the electric machine with the electric machine control circuit based on the calculated error.