Downloaded from https://www.everyspec.com ADS-79D-HDBK 3. DEFINITIONS Airworthiness: A demonstrated capability of an aircraft or aircraft subsystem or component to function satisfactorily when used and maintained within prescribed limits (Ref AR 70-62). Airworthiness Credit: The sustainment or reduction of baseline risk in allowance for a CBM Credit, based on the use of a validated and approved CBM system. The change can be specific to a specific item (component or part), tail number of an aircraft, or any group of items or aircraft as defined in the respective Airworthiness Release (AWR). Baseline Risk:
The accepted risk in production, operations, and maintenance procedures reflected in frozen planning, the Operator‘s Manuals, and the Maintenance Manuals for the baseline aircraft. Maintenance procedures include all required condition inspections with intervals, retirement times, and Time Between Overhauls (TBOs). CBM Debit: The approval of any unfavorable change, from the perspective of the maintainer, to the maintenance specified for a specific end item or component, such as an increase in inspections or reduction in Component Retirement Time established for the baseline system that is based on the incorporation of CBM as the approved maintenance approach.
For example, a legacy aircraft with a 2,000 hour Component Retirement Time (CRT) for a drive system component may mandate a decreased CRT for an installed component for which CBM Health Indicator (HI) values go above specified limits and the component is removed from the monitored aircraft. CBM Debits are mandated through a Safety of Flight/Aviation Safety Action Message or AWR restriction/limitation. CBM Credit:
The approval of any change to the maintenance specified for a specific end item or component, such as an extension or reduction in inspection intervals or Component Retirement Time established for the baseline system prior to incorporation of CBM as the approved maintenance approach. (For example, a legacy aircraft with a 2,000 CRT for a drive system component can establish a change to the CRT for an installed component for which CBM Condition Indicator (CI) values remain below specified limits and the unit remains installed on a monitored aircraft.) Often, CBM Credits may be authorized through an AWR. Condition Based Maintenance:
The application and integration of appropriate processes, technologies, and knowledge based capabilities to improve the reliability and maintenance effectiveness of Army Aircraft Systems and components. Uses a systems engineering approach to collect data, enable analysis, and support the decision-making processes for system acquisition, sustainment, and operations. Condition Indicator (CI): A measure of detectable phenomena, derived from sensors, that shows a change in physical properties related to a specific failure mode or fault. Condition Monitoring:
The technique of monitoring equipment parameters during operating conditions to look for signal behavior anomalies and long term trends in signal behavior. Confidence Bound: An endpoint of a confidence interval. Confidence Interval: An interval constructed from random sampling that, with known probability, contains the true value of a population parameter of interest. Confidence Level: The probability that a confidence interval contains the true value of a population parameter of interest. When not otherwise specified in this ADS, the confidence level should be assumed to equal 0.9 (or 90%). 5