E mttf or mtbf failure detection means and

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Unformatted text preview: Design the ORU surface structure so that no safety hazard is created during the removal, replacement, test, or checkout of any ORU during IVA or EVA maintenance; include cautions/warnings for mission or safety critical ORUs Design software to facilitate modifications, verifica tions, and expansions Allow replacement of software segments on-line without disrupting mission or safety critical functions Allow on- or off-line software modification, replacement, or verification without introducing hazardous conditions. • • • 6.4.4 Maintainability Techniques Analysis Tools and Maintenance Functional Flow Block Diagrams (FFBDs). Maintenance FFBDs are used in the same way as system FFBDs, described in Appendix B.7.1. At the top level, maintenance FFBDs supplement and clarify the system maintenace concept; at lower levels, Maintainability Lessons Learned from HST Repair (STS-61) When asked (for this handbook! what maintainability lessons were learned from their mission, the STS~61 crew responded with the following: • The maintainability considerations designed into the Hubble Space Telescope (HST) worked. • For spacecraft in LEO, don’t preclude a servicing option; this means, for example, including a grapple fixture even t trough it has a cost and mass impact. • When servicing is part of the maintenance concept, make sure that it's applied throughout the space craft. (The HST Solar Array Electronics Box, for example, was not designed to be replaced, but had to be nevertheless!) • Pay attention to details like correctly sizing the hand holds, and using connectors and fasteners designed for easy removal and reattachment. Other related advice: • • • Make sure ground-based mock-ups and drawings exactly represent the "as-deployed" configuration. Verify tool-to-system interfaces, especially when new tools are involved. Make provision in the maintainability program for high-fidelity maintenance training. they provide a basis for the LSA's maintenance task inventory. Maintenance Time Lines . Maintenance time line analysis (see Appendix B.7.3) is performed when time-to-restore is considered a critical factor for mission eff...
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This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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