Multi-unit systems pose logistical challenges in maintenance management, as finding a balance between availability and profitability is necessary. Choosing an appropriate maintenance policy can improve the use of available resources. The inclusion of cannibalization policies can offer greater responsiveness to spare part shortages. However, studying the effects of applying these policies in an existing system is only sometimes feasible. In this sense, simulation is presented as a valuable tool to investigate and understand these effects in a way that would not be possible. This article presents a simulation model to analyze different maintenance policies, including cannibalization, applied to a homogeneous multi-unit system of interchangeable components. The results show that even when problems arise in the supply chain of critical spare parts for the units, it is possible to maintain an acceptable availability rate through the implementation of cannibalization policies, which leads to an improvement in the operational availability of the units. Finally, the simulation tool also revealed advantages in describing transients of response to maintenance activities, which provides a complete understanding of how the system behaves in different situations.