Downloaded from https://www.everyspec.com ADS-79D-HDBK For aircraft with existing sensors and data collection systems, some portions of the analysis and design have already been completed. The decision to add additional components to the system follows the same flow as shown in Figure 4, with the emphasis focused on requirements for the additional aircraft system or component rather than the whole aircraft. It is important to review the existing system design and ensure that it meets the requirements for CBM as outlined in this ADS. Legacy sensors and data collection systems may lack elements which provide the means to modify the legacy maintenance program to CBM.
6.2 CBM for new developmental systems. In the development of a new aircraft or UAS, CBM should be considered when evaluating the maintenance approach as part of the initial requirements determination. This decision enables the incorporation of CBM elements as part of an integrated system of systems, potentially lowering the cost of incorporation of sensors, data collection hardware, aircraft systems and components. The true value of CBM is found in the integrated logistics support elements, and design studies and trade-off analyses should be cognizant of potential improvements in spare parts inventory cost, repair labor costs and overall system reliability.
Therefore, given the CBM system is critical to logistics and maintenance credit; it should be handled and maintained as a key component of the overall platform. The Government may also, at its discretion pending criticality of the maintenance item being monitored, use the CBM system to determine airworthiness of the aircraft. The Government will make the decision when an aircraft should be grounded by an inoperative CBM system. These operational considerations should be documented as part of the CBM Management Plan along with the steps to recovering normal logistics and maintenance following data loss or a time gap in CBM system operation.
Figure 5 shows a systematic approach to incorporation of CBM in a new acquisition. Establishing CBM as a system requirement by the Government is the first step, with this ADS serving as a source for guidance on the specific requirements. Both the Government and original equipment manufacturer (OEM) can use the ADS as the basis for the determination of requirements and the systems engineering processes related to design, validation and verification. Setting the requirement for CBM in the initial requirements document provides the greatest opportunity for integration of the sensors and data management hardware with other aircraft systems.
Once the preliminary design of the aircraft or UAS is underway, systems engineering methods are used to evaluate the reliability and maintainability of the emerging design. One of the outputs of this systems engineering process is the FMECA. The FMECA documents the failure modes and effects of the system. Upon completion of the FMECA a RCM analysis is performed to identify the appropriate failure management strategy for each identified failure mode. While the FMECA identifies all areas where CBM could be utilized, the RCM analysis identifies where CBM is the most appropriate failure management strategy.
Appendices C and D are useful in providing additional guidance on the selection and development of CIs for the components in the new design. Once the candidate list has been chosen, analysis and planning to determine how to develop data to support CI development will most likely consider seeded fault testing as well as modeling and simulation. Appendices C, D and H contain additional guidance for this part of the analysis. 32