Wind energy has become an important source of energy in the last years, proven to be an alternative to fossil power production. The advances in technology have allowed to exploit this resource in new environments. While offshore wind farms projects are growing at important rates, onshore farms are still the main contributors of this energy source. However, challenges to make wind farms projects profitable are still prevailing. In this context, maintenance activities have an important impact on energy production and operational costs. A linear optimization model is proposed to solve a maintenance scheduling problem for onshore wind farms. The model includes classical key concepts such as availability and revenues. Moreover, it includes technicians crew costs which are relevant when the maintenance operator is not the farm responsible. Therefore, a multi objective scheme is used to solve the problem via the epsilon constraint method. Preliminary results on modified instances previously used in the literature show that an approximation to the pareto front can be found for small instances.