# Development of a Maintenance and Spare Parts Distribution Model for Increasing Aircraft Efficiency
A total of 89% showed random failure characteristics for which a scheduled overhaul or replacement was not effective. These findings redefined maintenance by focusing thinking on system function rather than operation [3]. In the literature there are concepts and mathematical formulations how to solve the distribution of spare parts for aircraft fleets such as the METRIC model that provides a method for optimize procurement, distribute existing stock and redistribute the stock of a spare parts network for a given investment level [9]. However, disposition options for specific industries in different business scenarios are yet to be explored. There is a need of developing comprehensive strategic decision models for identifying conditions under which each alternative must be selected. There are very few studies on disposition decisions, and it offers a lot of potential for future research [10]. Future maintenance management research seeks for the development of optimization models capable of incorporating information about the repair and maintenance strategy and the engineering management policies [11]. In this context, the development of simulation-based models has high potential to provide practical guidance with different maintenance strategiesand policies [12]. In this regard, preventive maintenance and the frequency of preventive maintenance are a research focus in the field [12]. As an overview, spare parts management gaps lead to four future research areas: to develop integrated approaches to spare parts management, to define managerial guidelines, to develop maturity models as diagnosis tools, and to assess the benefits of methods by modeling the theoretical models into case study applications [13]. Furthermore, the distribution strategy for spare parts confront two main different options, allocation of spare parts in a central warehouse or in local or regional warehouses, as pointed out in a case study for spare parts logistics for the Chinese market [14]. These options refer to the strategic dilemma of defining the push, pull, or hybrid push-pull distribution strategy when designing the distribution network structure. As a result, the goal of the paper is to develop a model with the system dynamics methodology focused on assessing what-if scenarios for strategic decision-making related to maintenance management and spare parts distribution strategy. The main differences of the pursued conceptual model with other models for aircraft spare parts management is the high level of abstraction, its focus on assessing different policies and strategies with an integrated approach and not on the exact spare parts stock distribution or optimization. Therefore, the research paper pursues to analyze the impact of the distribution network design and strategy for spare parts management. In this context, the first goal is to design a conceptual model for maintenance management and spare parts distribution management in the aviation industry to optimize any given target system of an aircraft fleet over its life cycle. The second goal is to develop a simulation model by using the system dynamics methodology to compare fixed and dynamic planned maintenance intervals and the push and pull distribution management strategies and their impact on the overall target system of an aircraft fleet over its life cycle. Moreover, the third goal is to derive managerial implications based on the conceptual model designed and, on the modeling, and results of the simulation study. In conclusion, the main hypothesis is that the proposed methodology provides guidance to managers to optimize the coordination between the strategies of the spare parts distribution network and of the maintenance activities.