Reliability, Maintainability, and Supportability

Michael Tortorella is a Visiting Professor at RUTCOR (Rutgers Center for Operations Research) at Rutgers University, New Jersey, USA, and an Adjunct Professor of Systems Engineering at Stevens Institute of Technology, USA. He is the Founder and Managing Director of Assured Networks LLC, USA, a next-generation networks design, performance, and reliability consultancy. Tortorella was a Distinguished Member of Technical Staff at Bell Laboratories, USA, where he was recognized as a thought leader in design for reliability processes and technologies and network design and performance analysis. He holds the Ph. D. degree from Purdue University, Indiana, USA.

• Foreword xviiiAcknowledgments xxiiPart I Reliability Engineering1. Systems Engineering and the Sustainability Disciplines 31.1 Purpose of this Book 31.1.1 Systems Engineers Create and Monitor Requirements 31.1.2 Good Requirements are a Key to Success 41.1.3 Sustainability Requirements are Important Too 61.1.4 Focused Action is Needed to Achieve the Goals Expressed by the Requirements 71.2 Goals 81.3 Scope 101.3.1 Reliability Engineering 101.3.2 Maintainability Engineering 111.3.3 Supportability Engineering 121.4 Audience 121.4.1 Who Should Read This Book? 121.4.2 Prerequisites 131.4.3 Postrequisites 131.5 Getting Started 141.6 Key Success Factors for Systems Engineers in Reliability, Maintainability, and Supportability Engineering 151.6.1 Customer–Supplier Relationships 151.6.2 Language and Clarity of Communication 161.6.3 Statistical Thinking 171.7 Organizing a Course Using this Book 171.7.1 Examples 181.7.2 Exercises 181.7.3 References 181.8 Chapter Summary 19References 192. Reliability Requirements 202.1 What to Expect from this Chapter 202.2 Reliability for Systems Engineers 212.2.1 “Reliability” in Conversation 212.2.2 “Reliability” in Engineering 212.2.3 Foundational Concepts 212.2.4 Reliability Concepts for Systems Engineers 252.2.5 Definition of Reliability 282.2.6 Failure Modes, Failure Mechanisms, and Failure Causes 322.2.7 The Stress–Strength Model 342.2.8 The Competing Risk Model 352.3 Reliability, Maintainability, and Supportability are Mutually Reinforcing 362.3.1 Introduction 362.3.2 Mutual Reinforcement 402.4 The Structure of Reliability Requirements 412.4.1 Reliability Effectiveness Criteria 412.4.2 Reliability Figures of Merit 432.4.3 Quantitative Reliability Requirements Frameworks 442.5 Examples of Reliability Requirements 462.5.1 Reliability Requirements for a Product 462.5.2 Reliability Requirements for a Flow Network 482.5.3 Reliability Requirements for a Standing Service 502.5.4 Reliability Requirements for an On‐Demand Service 512.6 Interpretation of Reliability Requirements 532.6.1 Introduction 532.6.2 Stakeholders 542.6.3 Interpretation of Requirements Based on Effectiveness Criteria 552.6.4 Interpretation of Requirements Based on Figures of Merit 582.6.5 Models and Predictions 622.6.6 What Happens When a Requirement is Not Met? 632.7 Some Additional Figures of Merit 652.7.1 Cumulative Distribution Function 652.7.2 Measures of Central Tendency 652.7.3 Measures of Dispersion 692.7.4 Percentiles 702.7.5 The Central Limit Theorem and Confidence Intervals 712.8 Current Best Practices in Developing Reliability Requirements 732.8.1 Determination of Failure Modes 742.8.2 Determination of Customer Needs and Desires for Reliability and Economic Balance with Reliability Requirements 742.8.3 Review All Reliability Requirements for Completeness 762.8.4 Allocation of System Reliability Requirements to System Components 762.8.5 Document Reliability Requirements 792.9 Chapter Summary 792.10 Exercises 81References 823. Reliability Modeling for Systems Engineers 843.1 What to Expect from this Chapter 843.2 Introduction 853.3 Reliability Effectiveness Criteria and Figures of Merit for Nonmaintained Units 873.3.1 Introduction 873.3.2 The Life Distribution and the Survivor Function 903.3.3 Other Quantities Related to the Life Distribution and Survivor Function 953.3.4 Some Commonly Used Life Distributions 1023.3.5 Quantitative Incorporation of Environmental Stresses 1113.3.6 Quantitative Incorporation of Manufacturing Process Quality 1163.3.7 Operational Time and Calendar Time 1183.3.8 Summary 1203.4 Ensembles of Nonmaintained Components 1203.4.1 System Functional Decomposition 1203.4.2 Some Examples of System and Service Functional Decompositions 1213.4.3 Reliability Block Diagram 1243.4.4 Ensembles of Single‐Point‐of‐Failure Units: Series Systems 1253.4.5 Ensembles Containing Redundant Elements: Parallel Systems 1313.4.6 Structure Functions 1383.4.7 Path Set and Cut Set Methods 1393.4.8 Reliability Importance 1443.4.9 Non‐Service‐Affecting Parts 1453.5 Reliability Modeling Best Practices for Systems Engineers 1463.6 Chapter Summary 1463.7 Exercises 146References 1494. Reliability Modeling for Systems Engineers 1534.1 What to Expect from this Chapter 1534.2 Introduction 1544.3 Reliability Effectiveness Criteria and Figures of Merit for Maintained Systems 1544.3.1 Introduction 1544.3.2 System Reliability Process 1554.3.3 Reliability Effectiveness Criteria and Figures of Merit Connected with the System Reliability Process 1564.3.4 When is a Maintainable System Not a Maintained System? 1614.4 Maintained System Reliability Models 1624.4.1 Types of Repair and Service Restoration Models 1624.4.2 Systems with Renewal Repair 1634.4.3 Systems with Revival Repair 1664.4.4 More‐General Repair Models 1714.4.5 The Separate Maintenance Model 1724.4.6 Superpositions of Point Processes and Systems with Many Single Points of Failure 1774.4.7 State Diagram Reliability Models 1794.5 Stability of Reliability Models 1814.6 Software Resources 1824.7 Reliability Modeling Best Practices for Systems Engineers 1824.7.1 Develop and Use a Reliability Model 1834.7.2 Develop the Reliability–Profitability Curve 1834.7.3 Budget for Reliability 1844.7.4 Design for Reliability 1864.8 Chapter Summary 1864.9 Exercises 187References 1885. Comparing Predicted and Realized Reliability with Requirements 1905.1 What to Expect from this Chapter 1905.2 Introduction 1905.3 Effectiveness Criteria, Figures of Merit, Metrics, and Predictions 1915.3.1 Review 1915.3.2 Example 1925.3.3 Reliability Predictions 1935.4 Statistical Comparison Overview 1945.4.1 Quality of Knowledge 1945.4.2 Three Comparisons 1955.4.3 Count Data from Aggregates of Systems 1985.4.4 Environmental Conditions 1985.5 Statistical Comparison Techniques 1995.5.1 Duration Requirements 1995.5.2 Count Requirements 2085.6 Failure Reporting and Corrective Action System 2125.7 Reliability Testing 2145.7.1 Component Life Testing 2145.7.2 Reliability Growth Testing 2155.7.3 Software Reliability Modeling 2165.8 Best Practices in Reliability Requirements Comparisons 2165.8.1 Track Achievement of Reliability Requirements 2165.8.2 Institute a FRACAS 2165.9 Chapter Summary 2165.10 Exercises 217References 2186. Design for Reliability 2196.1 What to Expect from this Chapter 2196.2 Introduction 2206.3 Techniques for Reliability Assessment 2216.3.1 Quantitative Reliability Modeling 2216.3.2 Reliability Testing 2236.4 The Design for Reliability Process 2246.4.1 Information Sources 2266.5 Hardware Design for Reliability 2286.5.1 Printed Wiring Boards 2286.5.2 Design for Reliability in Complex Systems 2356.6 Qualitative Design for Reliability Techniques 2366.6.1 Fault Tree Analysis 2366.6.2 Failure Modes, Effects, and Criticality Analysis 2436.7 Design for Reliability for Software Products 2516.8 Robust Design 2526.9 Design for Reliability Best Practices for Systems Engineers 2576.9.1 Reliability Requirements 2576.9.2 Reliability Assessment 2586.9.3 Reliability Testing 2586.9.4 DFR Practices 2586.10 Software Resources 2586.11 Chapter Summary 2596.12 Exercises 259References 2607. Reliability Engineering for High‐Consequence Systems 2627.1 What to Expect from this Chapter 2627.2 Definition and Examples of High‐Consequence Systems 2627.2.1 What is a High‐Consequence System? 2627.2.2 Examples of High‐Consequence Systems 2637.3 Reliability Requirements for High‐Consequence Systems 2657.4 Strategies for Meeting Reliability Requirements in High‐Consequence Systems 2677.4.1 Redundancy 2677.4.2 Network Resiliency 2697.4.3 Component Qualification and Certification 2707.4.4 Failure Isolation 2777.5 Current Best Practices in Reliability Engineering for High‐Consequence Systems 2787.6 Chapter Summary 2797.7 Exercises 280References 2808. Reliability Engineering for Services 2828.1 What to Expect from this Chapter 2828.2 Introduction 2828.2.1 On‐Demand Services 2838.2.2 Always‐On Services 2848.3 Service Functional Decomposition 2858.4 Service Failure Modes and Failure Mechanisms 2868.4.1 Introduction 2868.4.2 Service Failure Modes 2888.4.3 Service Failure Mechanisms 2908.5 Service Reliability Requirements 2948.5.1 Examples of Service Reliability Requirements 2948.5.2 Interpretation of Service Reliability Requirements 2958.6 Service‐Level Agreements 2968.7 SDI Reliability Requirements 2978.8 Design for Reliability Techniques for Services 2988.8.1 Service Fault Tree Analysis 2998.8.2 Service FME(C)A 2998.9 Current Best Practices in Service Reliability Engineering 2998.9.1 Set Reliability Requirements for the Service 2998.9.2 Determine Infrastructure Reliability Requirements from Service Reliability Requirements 3008.9.3 Monitor Achievement of Service Reliability Requirements 3008.10 Chapter Summary 3008.11 Exercises 301References 3029. Reliability Engineering for the Software Component of Systems and Services 3039.1 What to Expect from this Chapter 3039.2 Introduction 3049.3 Reliability Requirements for the Software Component of Systems and Services 3059.3.1 Allocation of System Reliability Requirements to the Software Component 3059.3.2 Reliability Requirements for Security and Other Novel Areas 3089.3.3 Operational Time and Calendar Time 3099.4 Reliability Modeling for Software 3109.4.1 Reliability Growth Modeling for the Sequence of Failure Times 3109.4.2 Other Approaches 3129.5 Software Failure Modes and Failure Mechanisms 3129.5.1 Software Failure Modes 3129.5.2 Software Failure Mechanisms 3139.6 Design for Reliability in Software 3159.6.1 Software Fault Tree Analysis 3169.6.2 Software FME(C)A 3179.6.3 Some Software Failure Prevention Strategies 3179.7 Current Best Practices in Reliability Engineering for Software 3189.7.1 Follow Good Software Engineering Practices 3189.7.2 Conduct Design Reviews Focused on Reliability 3189.7.3 Reuse Known Good Software 3199.7.4 Encourage a Prevention Mindset 3199.8 Chapter Summary 3199.9 Exercises 320References 320Part II Maintainability Engineering10. Maintainability Requirements 32510.1 What to Expect from this Chapter 32510.2 Maintainability for Systems Engineers 32610.2.1 Definitions 32610.2.2 System Maintenance Concept 32710.2.3 Use of Maintainability Effectiveness Criteria and Requirements 32910.2.4 Use of Preventive Maintenance 33110.2.5 Levels of Maintenance 33110.2.6 Organizational Responsibilities 33210.2.7 Design Features 33310.2.8 Maintenance Environment 33310.2.9 Warranties 33410.2.10 Preventive Maintenance and Corrective Maintenance 33410.2.11 Maintainability for Services 33510.3 Maintainability Effectiveness Criteria and Figures of Merit 33710.3.1 Products and Systems 33710.3.2 Services 34010.4 Examples of Maintainability Requirements 34010.5 Maintainability Modeling 34210.5.1 Duration and Labor‐Hour Effectiveness Criteria and Figures of Merit 34210.5.2 Count Effectiveness Criteria and Figures of Merit 34410.6 Interpreting and Verifying Maintainability Requirements 34410.6.1 Duration Effectiveness Criteria and Figures of Merit 34410.6.2 Count Effectiveness Criteria and Figures of Merit 34610.6.3 Cost and Labor‐Hour Effectiveness Criteria and Figures of Merit 34810.6.4 Three Availability Figures of Merit 34810.7 Maintainability Engineering for High‐Consequence Systems 34910.8 Current Best Practices in Maintainability Requirements Development 35110.8.1 Determine Customer Needs for Maintainability 35110.8.2 Balance Maintenance with Economics 35110.8.3 Use Quantitative Maintainability Modeling to Ensure Support for Maintainability Requirements 35210.8.4 Manage Maintainability by Fact 35210.9 Chapter Summary 35310.10 Exercises 354References 35511. Design for Maintainability 35611.1 What to Expect from this Chapter 35611.2 System or Service Maintenance Concept 35611.3 Maintainability Assessment 35811.3.1 Maintenance Functional Decomposition and Maintainability Block Diagram 35811.3.2 Quantitative Maintainability Modeling 36011.4 Design for Maintainability Techniques 36211.4.1 System Maintenance Concept 36211.4.2 Level of Repair Analysis 36311.4.3 Preventive Maintenance 36911.4.4 Reliability‐Centered Maintenance (RCM) 36911.5 Current Best Practices in Design for Maintainability 37211.5.1 Make a Deliberate Maintainability Plan 37211.5.2 Determine Which Design for Maintainability Techniques to Use 37211.5.3 Integration 37311.5.4 Organizational Factors 37311.6 Chapter Summary 37411.7 Exercises 374References 374Part III Supportability Engineering12. Support Requirements 37912.1 What to Expect from this Chapter 37912.2 Supportability for Systems Engineers 38012.2.1 Supportability as a System Property 38012.2.2 Factors Promoting Supportability 38212.2.3 Activities Included in Supportability Engineering 38212.2.4 Measuring and Monitoring Supportability 38312.2.5 Developing and Interpreting Support Requirements 38312.3 System or Service Support Concept 38312.4 Support Effectiveness Criteria and Figures of Merit 38412.5 Examples of Support Requirements 38712.5.1 Support Elapsed Time (Duration) Requirements 38712.5.2 Support Count Requirements 38812.6 Interpreting and Verifying Support Requirements 38912.7 Supportability Engineering for High-Consequence Systems 39112.8 Current Best Practices in Support Requirements Development 39112.8.1 Identify Support Needs 39212.8.2 Balance Support with Economics 39312.8.3 Use Quantitative Modeling to Promote Rationally Based Support Requirements 39312.8.4 Manage Supportability by Fact 39412.9 Chapter Summary 39412.10 Exercises 395References 39513. Design for Supportability 39613.1 What to Expect from this Chapter 39613.2 Supportability Assessment 39713.2.1 Quantitative Supportability Assessment 39713.2.2 Qualitative Supportability Assessment 40013.3 Implementation of Factors Promoting Supportability 40113.3.1 Diagnostics and Fault Location 40113.3.2 Tools and Equipment 40213.3.3 Documentation and Workflow Management 40213.3.4 Staff Training 40313.3.5 Layout of Repair Facility and Workstation Design 40313.3.6 Design of Maintenance Procedures 40413.3.7 Spare Parts, Repair Parts, and Consumables Inventory 40413.3.8 Transportation and Logistics 40613.4 Quantitative Design for Supportability Techniques 40613.4.1 Performance Analysis of a Maintenance Facility 40613.4.2 Staff Sizing: The Machine Servicing Model 41213.5 Current Best Practices in Design for Supportability 41413.5.1 Customer Needs and Supportability Requirements 41413.5.2 Team Integration 41513.5.3 Modeling and Optimization 41513.5.4 Continual Improvement 41513.6 Chapter Summary 41613.7 Exercises 416References 417Index 419