RAM strategy for MORFEO toward the final design review

Complexity and operations costs are almost part of the game in the design of a modern instrument for ground-based telescopes. MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations), formerly known as MAORY is the first light MCAO instrument for the ELT and its design has been driven also from the Reliability, Availability, and Maintainability point of view since its early phases. Now entering the Final Design Review, particular attention has been considered in evaluation resources for preventive and corrective maintenance to reach the high level of availability requested by ELT requirements. After a general view of the philosophy adopted for the RAM analysis of MORFEO, the case of the Low Order sensor subsystem is proposed to show how requirements flow-down can be proactively used to ensure that the low-level characteristics, such as LRU accessibility, spare parts identification, and straightforwardness of maintenance operations can be addressed since the design phase.