In MDE, model transformations should be efficiently tested so that it may be used and reused safely. Mutation analysis is an efficient technique to evaluate the quality of test data, and has been extensively studied both for procedural and object-oriented languages. In this paper, we study how it can be adapted to model oriented programming. Since no model transformation language has been widely accepted today, we propose generic fault models that are related to the model transformation process. First, we identify abstract operations that constitute this process: model navigation, model's elements filtering, output model creation and input model modification. Then, we propose a set of specific mutation operators which are directly inspired from these operations. We believe that these operators are meaningful since a large part of the errors in a transformation are due to the manipulation of complex models regardless of the concrete implementation language.