An overview of an integrated Structural Health Monitoring approach based on Structural Intensity (SI) measurements is presented. The performances of the integrated system are evaluated by presenting numerical and experimental results concerning the different levels of detection, i.e. existence, extent and localization. Experiments are conducted on an aluminium stiffened panel, typical of many aerospace structures, where the damage is introduced in the form of loosened bolts. The characteristic nonlinear signature of this type of damage combined with SI measurements allows defining a new damage metric. This metric is able to address the different levels of detection using a single integrated approach and without requiring a quantitative baseline.