A system for detecting ice accretion on a rotor of an aircraft includes a processing system that is configured to: receive torque data indicative of actual torque supplied from an electric motor to the rotor; implement a model of the electric motor and the rotor that determines an estimated torque that should be supplied from the electric motor to the rotor; compute a load on the rotor from the actual torque and the estimated torque; compare the computed load to a predetermined magnitude; and when the computed load exceeds the predetermined magnitude, generate an alert that indicates ice is accreting on the rotor.