Downloaded from https://www.everyspec.com ADS-79D-HDBK FIGURE C-2. Effect of inspection time on risk reduction controlling factors should be maximized while the area of left tail of damage size crossing the critical crack size should be tightly limited to ensure meeting desirable level of reliability. Therefore, the effectiveness of inspection depends on capability of inspection and time of inspections. A late inspection would have great chance to detect damage, but risk of failure is high, while an early inspection may not capture damage growth in structural components.
To achieve the most efficient inspection within target reliability constraints, an ideal inspection plan should yield the minimum number of inspections while the underlying risk of failure resulting from misdetection doesn‘t exceed the maximum acceptable risk. Therefore, there is a window of opportunity to conduct inspections to achieve optimal solutions. As a further elaboration of the previous discussion, a technical approach which overcomes the aforementioned shortcomings associated with the current approach is proposed and further discussed herein.
The concept of the new approach is mainly based on a risk-based optimization to determine the best timings to perform inspections while satisfying the underlying reliability constraint and other CBM logistic requirements. Figure C-3 contains a notional sketch illustrating the effect of inspection and related repair / replacement on alleviation of damage progression and associated risk management. As depicted in the figure, the damage progression can be effectively reduced through a well planned inspection scheme. Detection of excessive damage progression triggers a CBM decision in repairing or replacing damaged components if the detected damage exceeds a threshold.
Therefore, the anticipated risk reduction can be achieved through effectively detecting premature damage during the inspections and restoring desired structural integrity by fixing or removing damaged components. 68