This part of ISO/TR 19972 provides a means for determining the reliability of hydraulic fluid power components using: a) estimates from a design analysis; b) analysis of laboratory testing to failure or suspension; c) analysis of field data; d) analysis of a substantiation test. These methods apply to the first failures without repairs, but exclude certain infant mortality failures. Specific component test procedures and exclusions will be provided in subsequent parts of ISO/TR 19972. This part of ISO/TR 19972 also provides calculation methods, reporting descriptions and examples of reliability calculations.