The sensitivity of integrated blade-disk couplings (BLISK) towards geometric variances are subject of investigation in the research project D4. Especially the impact of the coupling of different geometric variations within the blading on the aerodynamic performance are analyzed and assessed in detail. The geometric variations within the blading are caused by operation and regeneration. Industrial used Blisks as well as the research Blisks, designed and manufactured within the CRC, are supposed to be investigated. The essential result should be a method to evaluate the aerodynamic impact of geometric variances caused by operation and regeneration of a Blisk. This is an important basis for the planning of regeneration paths as well as the definition of new regeneration processes.