A cabin blower for an aircraft, the system comprising: a cabin blower compressor; an electric machine; and a controller configured to control the cabin blower system so that: in a cabin blower mode of operation, the cabin blower compressor is driven by power extracted from one or more spools of a gas turbine engine of the aircraft and provides a flow of air to a cabin of the aircraft. The controller may be further configured to control the system so that: in a rotor bow mitigation mode of operation, the cabin blower compressor is driven by the electric machine using electrical power from an electrical power source and provides a flow of air through a core of the gas turbine engine to remove heat from the core. A method of operating a cabin blower system of an aircraft is also provided.