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  • NASA-CR-200055

    Reliability and Maintainability Model (RAM)User and Maintenance Manual

    Prepared for

    National Aeronautics and Space Administration

    Langley Research Center

    under

    Grant No. NAGI-l-1327

    Entitled:

    O&S Analysis of

    Conceptual Space Vehicles

    Annual Report, Part II

    December 31, 1995

    Prepared by

    Charles E. Ebeling

    -)

    University of Dayton

    Engineering Management and Systems Department

    300 College Park

    Dayton, Ohio 45469-0236

    https://ntrs.nasa.gov/search.jsp?R=19960014865 2018-07-16T23:17:09+00:00Z

  • Reliability and Maintainability Model (RAM)User and Maintenance Manual

    Prepared for

    National Aeronautics and Space AdmhTistration

    Langley Research Center

    under

    Grant No. NAGl-l-1327

    Entitled:

    O&S Analysis of

    Conceptual Space Vehicles

    Annual Report, Part II

    December 3 l, 1995

    Prepared by

    Charles E. Ebeling

    University of Dayton

    Engineering Management and Systems Department

    300 College Park

    Dayton, Ohio 45469-0236

  • Preface

    This document is the second version of the User and Maintenance Manual

    developed for the Reliability and Maintainability (RAM) Model under NASA (LRC) Grant

    No. NAG1-1-1327. The first version was completed in December 1994 as part of the

    same research grant. Numerous changes have been made to the model during the current

    research year making the previous manual obsolete. These changes are discussed in the

    annual report "O&S Analysis of Conceptual Space Vehicles," Part I, December 31,

    1995. This document is designed to be self-contained and therefore repeats some

    information found in the previous manual and in previous reports. As further experience

    with the model is obtained, additional changes and enhancements are likely. Planned

    future research includes updating the underlying data base used to generate the estimating

    equations.

    The principle researcher for this effort is Dr. Charles Ebeling, Department of

    Engineering Management and Systems, School of Engineering, University of Dayton,

    Dayton, Ohio 45469. Comments concerning this document and the accompanying

    software are welcome.

  • Table of Contents

    page

    List of Figures .......................................................... v

    List of Tables .......................................................... v

    Chapter 1 Introduction .................................................... 1

    1.1 Background .................................................... 1

    1.2 Model Development ............................................... 11.3 Overview ..................................................... 4

    Chapter 2 Methodology ...................................................

    2.1 Parametric Analysis ..............................................

    5

    5

    2.2 Computation of MTBM ............................................ 52.3 Mission Profile ................................................. 7

    2.4 Reliability Calculations ............................................. 8

    2.5 Maintainability Estimates ........................................... 10

    2.6 Manpower .................................................... 11

    2.7 Spare Parts Requirements ........................................... 132.8 Vehicle Turn Times .............................................. 14

    2.9 External Tank (ET) & Liquid Rocket Booster (LRB) .......................... 15

    Chapter

    Chapter

    3 Model Design and Execution .......................................... 17

    3.1 Model Design .................................................. 17

    3.2 Initialization Sequence ............................................. 19

    3.3 Main Menu Options .............................................. 20

    3.4 Computational Sequence ............................................ 24

    4 Model Input ....................................................4.1

    4.2 Modes of

    27

    Primary Input Menu .............................................. 274.1.1 Add/Delete a Subsystem ...................................... 274.1.2 Select Shuttle/Aircraft ....................................... 27

    4.1.3 Update/Display Primary System Menu ............................. 28

    4.1.4 Update/Display Subsystem Weights ............................... 29

    4.1.5 Update/Display Secondary variables .............................. 30

    4.1.6 Update/Display Computational factors ............................. 30

    4.1.7 Update/Display Mission Profile ................................. 3 l

    4.1.8 Update/Display Subsystem Operating Hours ......................... 31

    4.1.9 Update/Display Redundancy Specification ........................... 324.1.10 Update/Display LRB/ET Reliability Data .......................... 33

    4.1.11 Update/Display Shuttle MTBMs & MHMA's ....................... 34

    4.1.12 Change Scheduled Maintenance ................................ 354.1.13 Establish Subsystem Reliabilities ................................ 35

    Operations .............................................. 36

    iii

  • 4.3 Computational Factors ............................................. 38

    4.3.1 Technology Factor ......................................... 384.3.2 Subsystem Calibration ....................................... 39

    4.3.3 Critical Failure Rates ....................................... 40

    4.3.4 Removal Rates ........................................... 41

    4.3.5 Fraction Off-Vehicle ........................................ 424.3.6 Crew Size .............................................. 43

    4.3.7 Fraction Inherent Failures ..................................... 44

    Chapter 5 Output Displays & Reports ........................................... 455.1 Screen Displays (output) ............................................ 45

    5. I. 1 Reliability Report .......................................... 45

    5.1.2 Maintainability Report ....................................... 48

    5.1.3 Manpower report .......................................... 50

    5.1.4 Spares Report ............................................ 52

    5.1.5 Vehicle Turntime Report ..................................... 53

    5.1.6 System Performance Summary .................................. 55

    5.1.7 Aggregated System Report .................................... 565.1.8 Initial MTBM and MTTR values ................................ 58

    5.2 Report Generation ............................................... 59

    5.3 Parametric Analysis .............................................. 59

    Chapter 6 - Study Analyses & Procedures ......................................... 60

    6.1 General ...................................................... 60

    6.2 Input Procedures ................................................ 60

    6.3 Analyses Methods ............................................... 62

    6.3.1 Trade-off Studies and Sensitivity Analysis .......................... 626.3.2 Turntime, Fleetsize and Mission Rates ............................. 62

    6.3.3 Manpower Assessments ...................................... 62

    6.3.4 Reliability Specification ...................................... 63

    BIBLIOGRAPHY ........................................................ 64

    APPENDIX

    A Glossary ..................................................... A-I

    B Study Scenarios .................................................. B-1

    C Source Listing ................................................... C-1D Variable Definitions ............................................... D-1

    iv

  • List of Figures

    page

    1. Mission Profile ....................................................... 7

    2. Main Menu .......................................................... 20

    3. Computational Flow .................................................... 244. Input Parameter Menu ................................................... 275. Mission Profile ....................................................... 31

    6. Subsystem Operating Hours ................................................ 31

    7. Subsystem Redundancy .................................................. 32

    8. LRB/ET Screen Display/Update ............................................. 33

    9. Shuttle MTBM/MHMA Update/Display ........................................ 34

    10. Scheduled Maintenance - Input/Display ........................................ 35

    11. Establish Subsystem Reliability ............................................ 36

    12. Subsystem Weights .................................................... 37

    13. Secondary Variable Menu ................................................ 37

    14. Computational Factors Menu .............................................. 38

    15. Annual Technology Factor ................................................ 38

    16. Subsystem MTBM/MHMA Calibration Factor ................................... 3917. Critical Failure Rate ................................................... 40

    18. Removal Rate ....................................................... 41

    19. Fraction Off Equip .................................................... 4220. Crew Size/Nbr Crews ................................................... 43

    21. Fraction Inherent Failure Screen ............................................ 44

    22. Screen Display (Output) Menu ............................................. 45

    23. Reliability Report ..................................................... 46

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