An experimental approach was adopted to understand service damages such as crack initiation and surface degradation of bolted joints used in the junction technology of aircraft air bleed valve systems. A vibratory testing stage combined to Digital Image Correlation (DIC) focus on an experimental model device of valve body/actuator body junction. DIC coupled with in situ tribological observations and a Finite Element Model (FEM) has been used to identify more clearly local contact conditions. This approach has enlightened peeling-off and micro-slips instabilities under vibratory loadings, leading to third body formation in bolted joints contacts. The morphology of such third body is placed at the focus of damages observed in involved air bleed valve systems.