The majority of aircraft engine life cycle assessment (LCA), and more generally aeronautical products, focuses on the use, the extraction of raw materials, and the manufacturing phases. This focus seems logical since they represent a priori the most significant sources of impacts on the environment. The maintenance phase is usually overlooked and roughly modeled. However, it is precisely relevant as aircraft engines are high-value products, and airlines strive to maintain their engines to last the longest as possible. The maintenance phase can be considered as an additional life cycle for the product. It implies a vast diversity of swapped parts and repairs. The detailed LCA modeling would be an intricate analysis that would require huge work of inventory. Nevertheless, one has to tackle this objective, as LCA tends to be a reference methodology not only for environmental disclosure but also for eco-design activities for the aeronautical sector. This chapter proposes a methodology to model the overall maintenance of an aircraft engine throughout its whole life for LCA purposes. This model applies to the whole engine or parts of it. A generic flow diagram of maintenance in workshops has been built based on industrial experience. Then the simplifications of the model, required to make it viable, are introduced. The feasibility is evaluated with a use case on the repair of a specific engine part. Finally, this chapter proposes a discussion about the limits related to the assumptions, the simplifications, and the areas of improvement.