Corrosion and fatigue induced metal-loss and cracks are common problems for missiles and aircraft structures. A wide range of field conditions such as humidity, temperature, stress, cathode potential, and coating conditions, etc. all contributes to the electrochemical reaction between the incipient corrosive agent molecule and the structural metal matrix. The weakened inter-atomic force leads to the material loss, pits or crack growth and eventually structural failure. We propose a new approach to detect and characterize the corrosion and cracks in missile and aircraft structures. The technique consists of very small, low cost guided wave leave-in-place health monitoring sensors known as piezo-disks, innovative Correlation Analysis Technique (CAT) for fast defect sizing and localization, and a miniaturized local computing device with data acquisition and processing capabilities and wireless module for remote monitoring. It is envisioned the total cost of this system will be less than $1500.