ADS-79D-HDBK Downloaded from https://www.everyspec.com It is important to note that the term verification refers to testing against the requirements as stated in the Configuration Specification Document. The algorithm, configuration and other system elements designed for the component‘s health credit will be tested to assure correct implementation. Whether or not they function appropriately in the real world application is determined during validation. Given this definition, the ―Verify CI/HI Implementation‖ step only needs to prove that the system elements work as specified. Such verification can be conducted on a bench-type or simulation-type test.
If the verification proves that the requirements of the system elements are met, verification is complete. At the end of verification, a ―CI/HI Verification Document‖ needs to be generated that captures the verification tests and process. K.5.1.2 Mechanical Health Credit Validation Process Upon successfully verifying the credit methodology, the production unit is generated. The production unit is essential for validating the methodology. This section explains the process by which the Mechanical Health Credit methodology should be validated. See Figure K-7 for the flow chart.
The entry criterion for the Mechanical Health Credit Validation Process is that the CI/HI verification process must have been completed. The starting assumption here is that upon successful completion of verification, the system elements will now be production software. Validation can only be performed on production software. To continue with the validation process, the next step is to establish validation requirements and metrics. Figure K-8 has mentioned a few metrics. At this point, a decision regarding which validation path should be used. Validation of a health credit can be achieved by one of the following three processes:
Data Validation, In-Service Validation or Seeded/Natural Fault Test Validation. Data Validation: To go down this process path, samples of fault cases for the target component should be available. If this data is available, the fault cases can be used to determine whether the CI/HI methodology is able to accurately diagnose the health of the component. However, if such a dataset is not available, one of the other validation processes needs to be followed. The data validation is successfully complete if the candidate system can accurately (based on criteria established in steps before) diagnose the health of the component.
Upon successful validation, the candidate system can acquire Maintenance Credit for the component. A document about the validation process will have to be generated to close out the process. Refer to Appendix D for more details on identifying candidate features. In-Service Validation: In order to perform in-service validation, the candidate algorithm and software has to be installed on the target platform. Aircraft operations will continue normally. The idea behind this validation process is that the system will acquire Maintenance Credit when it successfully diagnoses the target component‘s health through normal aircraft operation. 204