ADS-79D-HDBK Downloaded from https://www.everyspec.com FIGURE K-11. Examples of time related considerations for usage spectrum monitoring. Some of these components remain on a single airframe over their service life while others can migrate between aircraft within a unit (as a unit asset) and others can migrate anywhere within the fleet over their service life. This interaction of usage variability and component migration should be considered in data collection for spectrum updating and fatigue life management approaches used for the introduction of updated spectra and other options such as using fatigue life factors for unique fleet populations.
K.5.3.1 Structural Usage Monitoring Credit Verification Process. In this section, a detailed view of the Structural Usage Monitoring Credit Verification process is provided. This process also discusses certain development steps needed to have a successful verification. The entry criterion for starting the usage credit verification process is that the target usage credit has been identified and the feasibility with regards to data coverage has been assessed as shown in Figure K-12. The selected usage credit could be limited to usage tracking only, or could also include calculated part fatigue damage fraction tracking.
Calculated fatigue damage fraction tracking is a requirement for usage credits where individual components are retired based on actual usage. Guidance on the verification requirements related to the fatigue life management (FLM) elements of the identified credit can be found in Appendix A. Guidance on the requirements related to the regime recognition elements of the identified credit can be found in Appendix B. 212