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Validation and Verification Processes to Certify SHM Solutions for Commercial Aircraft Applications



Reliable Structural Health Monitoring (SHM) systems can automatically process data, assess structural condition and signal the need for human intervention. While ad-hoc efforts to introduce SHM into routine aircraft maintenance practices are valuable in leading the way for more widespread SHM use, there is a significant need for formal SHM technology validation and certification processes to uniformly and comprehensively support the evolution and adoption of SHM practices. Such a plan must contain input from aircraft manufacturers, regulators, operators and research organizations so that the full spectrum of issues including design, deployment, performance and certification is appropriately considered. Currently, there are no guidelines for SHM system designers or agreed-upon procedures for assessing the performance of SHM systems. Through the operation of the FAA’s Airworthiness Assurance Nondestructive Inspection Validation Center (AANC), the FAA secured its mission to provide independent validation of technologies intended to enhance the structural inspection of aircraft. A natural extension of this mission is to incorporate SHM in these validation efforts. The AANC’s validation approach is designed to address the equipment, the inspection task, the resolution required, the inspection procedures, the conditions under which the inspection will occur, and the potential inspector population. To carry out the validation process, knowledge of aircraft maintenance practices must be coupled with an unbiased, independent evaluation. The AANC has designed, implemented, and analyzed the results from a wide range of statistically-relevant experimental programs to quantify the reliability of inspection methods as deployed at commercial aircraft maintenance facilities. Much of this methodology to quantify NDI performance can be adapted to the validation of SHM systems. However, it is important to recognize the unique validation and verification tasks that arise from distinct differences between SHM and NDI deployment and flaw detection. An important element in developing SHM validation processes is a clear understanding of the regulatory measures needed to adopt SHM solutions along with the knowledge of the structural and maintenance characteristics that may impact the operational performance of an SHM system.

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