Abstract: Many CFM56 3 No.3 aft air/oil seals were found to be separated due to the performance deterioration of Non Asbestos Adhesive.The experience of China Southern Airlines shows that accompanying the onset of separation,it can often be observed,the oil consumption increases and brown non metal chips emerge.These phenomena prompted the authors to initiate a way to control the separation by monitoring oil consumption and Magnetic Detectors.Meanwhile,the mechanics of the seal separation and relative modification information are also introduced in the paper.