OBUU analyses the MRO Centre or Maintenance Organisation support structure; Spares and GSE Suppliers, MRO Centres, Operators and Fleet Alocation. OBUU will collect Aircraft Maintenance and Spares Reliability data, along with the Organisation Structure and Operational Data. OBUU will perforn a simulation resulting in a Cost / Efficiency Curve built by optimum points of Availability vs. Investment. OBUU Calcul v.1.3.1 will produce an optimised stock list that shows the exact number of stock per P/N needed to obtain the necessary availability with the investment level selected. With the optimised stock levels, OBUU is also capable of analysing the needs of the Stock in time to implement buy or rent policies and aid with investment strategic decission making.