Timely, reliable supply of customers with spare parts is a key factor for business success in many branches. In the field of aviation the competition and cost pressures in the MRO sector (Maintenance, Repair and Overhaul) increased strongly in recent decades. Large maintenance organizations offer component pooling services for aircraft operators. A main challenge in the processes of MRO service providers is the calculation of the optimal stock level for pool components. The basis of an optimal inventory planning for the supply of spare parts is the quality of the demand input parameters used for the calculation. This paper describes the processes and the challenges of the MRO spare parts management as well as the approaches of a research project to face these challenges.