New requirements have been put forword for the civil aircraft customer service with the civil aviation industry booming. While providing the high quality products, how to efficiently guarantee the normal operation of the fleet becomes a focus of the current research topics. Both the maintenance engineering and spares engineering are the significant components of the civil aircraft customer service. From the practical engineering application, this paper introduced the preparation process of spares engineering. Based on the principle of the flight serviceability, the research method of the maintainability engineering was emphatically discussed. The verification examples are demonstrated that the method presented is effective and practical for RSPL to meet the requirements of the spares support.