How Good is Your Inspection? How Do You Measure Up?
Engineering design based on damage tolerance criteria requires assuming the presence of flaws that are not detected in production and life-cycle maintenance operations [1,2]. Structural integrity is assured during service life by material selection and design load control to accommodate flaws that cannot be, or are not detected during final inspection and acceptance. Nondestructive evaluation (NDE) is the primary basis for the assumed detection capability (no flaws present that are larger than the assumed size) and it is necessary to quantify to applied NDE detection capabilities to assure that design / structural integrity requirements are met. NDE methods involve multiple application parameters and the resultant detection capability varies with each application. For critical structures, it is necessary to quantify detection capabilities for each application and to maintain rigid process control to assure that the detection capability is constant. The smallest flaw detected is not important. The largest flaw missed is the parameter of primary concern.