NASA MSFC HDBK 3074 : 2002

FOREWORD
1.0 SCOPE
2.0 APPLICABLE DOCUMENTS
2.1 Applicable Documents
2.2 Reference Documents
3.0 ACRONYMS AND DEFINITIONS
3.1 Acronyms and Abbreviations
3.2 Definitions
4.0 THE NEED FOR AN ORU SELECTION PROCESS
5.0 EFFECTIVE ORU SELECTION IS INTEGRAL TO SUPPORTABILITY
    AND SYSTEMS ENGINEERING
5.1 Systems Engineering
5.2 Supportability Engineering
5.3 ORU Selection
6.0 ORU SELECTION METHODOLOGY
6.1 Initial data
    6.1.1 Collect the system RMS requirements
    6.1.2 Identify the system architecture
    6.1.3 Allocate the RMS requirements to the system
          architecture
    6.1.4 Identify the maintenance items
    6.1.5 Identify the ORU selection criteria
6.2 Initiate the ORU selection process/flowchart
6.3 Reiterate the ORU selection process as the system
    definition matures
7.0 ORU DESIGN CONSIDERATIONS
7.1 Safety
7.2 Reliability
7.3 Human factors
    7.3.1 Accessibility
    7.3.2 Interfaces
    7.3.3 Restraints
    7.3.4 Handling
    7.3.5 Labeling
7.4 Other design considerations
    7.4.1 Special tools or equipment
    7.4.2 Commonality
    7.4.3 Design packaging
    7.4.4 Fault detection, isolation and recovery (FDIR)
    7.4.5 Maintenance verification
    7.4.6 Repair level analysis (RLA)
    7.4.7 Technical data and documentation (TD&D)
8.0 SUMMARY
Appendix A - ORU Selection Flowchart Logic
Appendix B - ORU Selection Flowchart Logic Worksheets

This handbook provides guidance on selecting the appropriate ORU items to ensure that a flight system is supportable on-orbit.