For maintenance, repair and overhaul (MRO) of aircrafts, used parts from other airplanes are used. The sell, loan and exchange of used aircraft parts is a big market. MRO providers offer flat rate deals to airlines that cover all expenses of MRO operations. These deals require a lot of operations research: Demand for spare parts need to be forecasted, values for spare parts in various conditions must be determined and most efficient economical use of existing stock calculated. The presenter will give a brief insight in a solution for a big MRO provider. Applied methods include forecasts based on stochastic processes for demand prediction. Additionally, a combination of various regression models is used for value determination. Optimization models support buy/sell decisions and the most efficient use of stock parts. The models itself are of interest not only due to their complexity but also due to the enhancements to handle all kind of missing data cases. The solution for this MRO provider is tailor made. The presentation will show examples for other custom-made OR solutions. That should support the thesis that successful OR implementations are mostly tailor made.