The S-D-I-P-F Safety Reliability Curve Begins With the 1979 Birth of the P to F Interval. “Determining the interval for on-condition inspection of an item subject to metal fatigue. Once the rate of decline in failure resistance has been determined, an inspection interval “ΔT” is established that provides ample opportunity to detect a potential [P] failure before a functional [F] failure can occur.” Excerpt from: F.S. Nowlan, “Reliability-Centered Maintenance,” 1979. Over 40 years...
