Downloaded from https://www.everyspec.com ADS-79D-HDBK require 90% probability of detection and 90% confidence. The number of ground truth data samples is determined by Weibull or other similar analysis. D.4.3.2 Level 2: Mature CIs/HIs. CIs and HIs that are supported by a minimum of 5 TP ground truth data samples and have a minimum accuracy performance of 90% are Mature and can be used to supplement standard maintenance practices in the field. Upon achieving a mature status, it is only necessary to increase the size of a CI/HI‘s ground truth dataset if maintenance credits are sought. The majority of CI/HIs will not need to pass beyond this level of certification.
Mature CI/HIs can be used by the Project Manager to define maintenance logistics (yellow/orange thresholds) and do not exceed limits (red thresholds). D.4.3.3 Level 3: Established CIs/HIs. CIs and HIs that are supported by a minimum of 1 TP ground truth data sample and have a minimum accuracy performance of 60% are Established. These CI/HIs can be used by the Project Manager to provide maintenance guidance that is recommended or optional. These indications are usually not associated with mandatory maintenance (red thresholds). D.4.3.4 Level 4: Developmental CIs/HIs. CIs and HIs that are supported by a minimum of 1 TP ground truth data sample are Developmental.
This level of classification has no minimum accuracy requirement and is generally not associated with field usage. It is recommended that if the Project Manager places developmental CI/HIs into the field environment, the thresholds be set arbitrarily high or not at all. D.4.3.5 Level 5: Nascent CIs/HIs. CIs and HIs that are only supported by a physics of failure model and may be taken directly from literature for deployment into a ground station for post processing or on-board with no thresholds are Nascent. These CIs and HIs are added to the data collection system so that a ground truth dataset can be built over time. D.4.3.6 Level 6: Retired CIs/HIs.
CIs and HIs that are either obsolete, exhibit poor accuracy performance (lower than 50%), or have an unacceptable FN/FP rate as determined by the Project Manager/Engineer are Retired. D.4.4 Health indicator (HI) usage. HIs are indicators of maintenance action based on the value of one or more CIs. The HI provides the link to the standard maintenance action contained in the appropriate Technical Manual (TM) that restores the operation of the system and aircraft to normal levels.
HIs serve the function of Health Assessment (HA) in the MIMOSA Standard, as well as Advisory Generation (AG) in the International Standards Organization (ISO) Standard, as they describe the health of the system and the action to be taken to restore the system to normal. HIs should be compatible with troubleshooting and repair tasks as published in the appropriate TM. HIs should be directly correlated to a maintenance action that can be accomplished by the maintainer and should convey the immediacy of the maintenance action. In their simplest form, HIs can be binary (i.e.
―No Maintenance Required‖ and ―Maintain Immediately‖); however, in order to achieve CBM goals they should be given a range of values and meanings. (See Figure D-2) For example: a. Green – No Maintenance required/Monitor frequently b. Yellow – Maintain as soon as practical c. Orange – Maintain as soon as practical/Non-flight critical maintenance d. Red – Maintain as soon as possible 80