Development and Performance Quantification of an Ultrasonic Structural Health Monitoring System for Monitoring Fatigue Cracks on a Complex Aircraft Structure

Aircraft structural components may have known "hot spots" where any initial damage is anticipated to occur or has consistently been observed in the field. Automated inspection of these areas, or hot spot monitoring, may offer significant time and cost savings for aircraft maintainers, particularly when the hot spots exist in areas that are difficult to access or where traditional NDE inspection methods will not work. This paper discusses the development of a hot spot monitoring system for a metallic lug component using ultrasonic elastic waves generated by piezoceramic elements. The development process utilizes a formal SHM system design framework developed by Boeing and AFRL and uses a multi-step approach progressing from simple coupon tests to the full scale component for system validation. A Probability of Detection (POD) approach is being developed to quantify the performance of the SHM system based on the selected operation scenario and demonstrate the capability relative to current Aircraft Structural Integrity Program (ASIP) requirements. Further POD verification and validation plans to address system reliability and operational conditions are discussed.