The present paper provides that robustness is the facility of complex computer-aided engineering systems of keeping its feature invariable along the certain perid of time. The detecting of indications which testify that system is not responding adequately to input disturbances may be realized by: comparing real data on assembly output with number of reference artifacts which correspond to specific states of disturbances; comparing real data on assembly output with a normal reaction to the actual set of input signals. To increase the resilience of monitoring data of engineering system the majority principle and the Byzantine agreement method are used.