Dynamic components for helicopters are typically designed for fatigue using the Palmgrell/Miner rule. This rule, also known as the safe-life methodology, determines a 'safe-life' for the component from an assumed usage spectrum, associated maneuver stress levels, and the S/N curve for the component. However, the inability to quantify reliability, the cost of retiring parts that probably have no damage, and the fact that the crack that usually results in aircraft part failure is not modeled, have led toward the damage tolerance design approach being implemented into the Federal Aviation Regulations (FAR) by the Federal Aviation Administration (FAA). This paper investigates the accuracy of several damage-tolerance analysis methods. Many helicopter components are subjected to high cycles, low stresses, and high stress ratio loading. Rotorcraft manufacturers have primarily relied on the classical safe-life approach to design the rotor components. The results from the round-robin challenge have shown that technical challenges must be solved before these damage tolerance methods can be generally applied to the rotorcraft components. Analytical and experimental approaches in determining crack growth rates in the threshold region are not well established and remain an active research topic. In addition, the material test data for the threshold region is limited and exhibits significant, scatter. How this data is treated will significantly impact structural integrity assessment, especially for rotorcraft components. Three commonly used fatigue crack growth programs originally indicated large differences in crack growth life prediction. These 'predictions' were only improved after the test results became available. However, by using the methods described in this text the 'differences' were eventually reduced to acceptable levels. Duplicating the shape of the crack growth curve for the test specimen proved to be very difficult. A detailed boundary element model (BEASY) was used to create stress intensity values for the test specimen. Using the BEASY values improved the curve shape for the predictions, however, the crack life predictions were still off by a factor of 21. In the classical safe-life design, the working or design S/N curve is derived from a statistical knockdown from the test mean curve. For any component whose crack growth life is sensitive to the threshold stress intensity range, a safe crack growth design should also be based on a statistical knockdown on the threshold stress intensity. Although damage tolerance has been used to assess many field problems, the rotorcraft community remains uncommitted to support general use of damage tolerance in the design and certification of rotorcraft components. This trend can be attributed to the inability to derive meaningful inspection intervals for the dynamic components.