The quality of aircraft and rocket engines depends primarily on the geometric accuracy of assembly units and parts. Mathematical models implemented in the form of computer models are used to predict quality indicators (in particular, assembly parameters). The work presents a numerical model for predicting assembly parameters of the rotors based on the use of actual surfaces of the parts obtained as a result of measurement on coordinate measuring machines and of mathematical modeling. Aircraft engine turbine rotor parts surfaces are measured on a coordinate measuring machine. Experimental assemblies of three parts were carried out. The measurement error of the parts does not exceed 5 µm, of assembly – 10 µm. Face and radial run-outs were measured for four positions of the disc and retainer in the shaft assembly, with run-outs ranging from 0.08 mm up to 0.1 mm. Calculations of face and radial run-outs of the disc with respect to the base surfaces of the shaft were made using the developed digital model. Relative deviations of the calculated values from the experimental values do not exceed 10%.