This study provides new insights in the problem of lumpy aircraft spare parts demands by incorporating new drivers that have an impact on the failure patterns of aircraft components. The study introduces a model and presents corresponding results that obtains component failure characteristics based on data from an aircraft manufacturer. A Monte Carlo simulation technique is used to take dierent repair qualities, fleet sizes, environmental conditions and shared component pool strategies into account. The outcome is evaluated to capture the impact of these parameters. Based on the occurring patterns of the failures, the demand patterns can be inferred. The study confirms the conclusion from previous research that the fleet size is the main contributor to the unpredictability of the demands of spare parts, but notes that this conclusion is not always usable in practice, as practical limitations regarding the extension of fleets are in play. The study concludes that an improvement of the repair quality is beneficial for the variance of the demand and the total amount of failures over time.