# Development of a Maintenance and Spare Parts Distribution Model for Increasing Aircraft Efficiency
## 5 Conclusions  
This research provided a methodology and results from a case study analysis to assess the design of distribution networks for spare parts throughput and the related whole life cycle cost of an airplane. This sort of evaluation is normally needed when making decisions regarding new distribution network configurations, distribution strategies, and maintenance program definitions. For this reason, many different agents can obtain benefits and methodological inputs for their assessments such as suppliers, manufacturers, airlines, users, and maintenance companies. The methods described in this document can be applied throughout the life cycle of an aviation item to examine trade-offs between distribution performance, inventory cost  
Figure 11: Managerial implications—methodology and steps (own elaboration). Figure 12: Decision-making influenced by the methodology of the research study (own elaboration). and aircraft availability. In this context, after the realization of this research study, the importance of distribution network design and management for spare parts in the aviation industry has been demonstrated. We draw the following conclusions from this study:  
* System dynamics provides the necessary notation and functionality to design distribution related models using Vensim (commercial software);
* Simulation of frameworks can be used to compare different distribution network approaches as well as different maintenance planning models;
* According to the results of the comparison here, it has been shown that in most cases a push strategy together with variable maintenance intervals gives a better response for aircraft availability, while a pull strategy with variable maintenance intervals provides better results in terms of inventory costs. Moreover, the variable maintenance intervals are a key factor to reduce the consumption of spare parts and the related maintenance time for replacements. The better response of the push strategy in terms of aircraft availability is due to the stable and homogenous demand among airports. The demands analyzed did not have high volatility or constant demand pattern changes. As a result, the allocation of stocks close to the maintenance locations provided better results. In terms of cost, further analysis must be performed to determine which configuration is optimal. This also depends on a company's goal and the overall system condition. * The proposed approach can increase the efficiency of distribution networks. It shows how the proposed conceptual model and its methodology can provide a useful tool for managers to compare different distribution network designs and maintenance programs and decide which best meets the target aircraft availability with the lowest costs possible, increasing delivery service with less stocks and more efficient management. The methods and strategies used have their unique advantages and disadvantages and each company's objectives and external environment will determine the preference of use. Two major limitations of the research paper were: no experts in the field were involved in the development process of the conceptual or the simulation models and the models were not applied to any real aircraft fleet for maintenance and distribution management. In summary, it is important to determine other means of investigation or possible ways to improve the performed project.