More-electric aircraft architectures are a well-known approach to reduce the environmental impact of air transport as well as to improve on fuel efficiency. Specifically, electric actuation of flight control surfaces is also seen as an effective way to improve aircraft efficiency while reducing operational cost. Electromechanical actuators (EMA) for flight control surfaces are complex components and a thorough and integrated optimisation of the EMA is required in order to be competitive with existing hydraulic solutions. In this context, this paper presents details of the design optimisation of a fault-tolerant permanent magnet (PM) motor drive for an aerospace application, in particular for an EMA in a helicopter primary flight control application. Emphasis is put on the integrated weight optimisation of the whole motor drive. The fault-tolerant EMA actuation system is described in detail and the design and optimisation of the dual channel, fault-tolerant electrical machine and the power converter within the EMA structure is presented. Prototypes of the electrical machines and the power converters were manufactured and measurement results are presented, validating the models used in the optimisation process.