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MIL-HDBK-338B root cause analysis


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NOT MEASUREMENT SENSITIVE MIL-HDBK-338B 1 October 1998 SUPERSEDING MIL-HDBK-338A 12 October 1988

MILITARY

HANDBOOK ELECTRONIC RELIABILITY DESIGN HANDBOOK

This handbook is for guidance only. Do not cite this document as a requirement

AMSC N/A

AREA RELI

DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.

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MIL-HDBK-338B FOREWORD FOREWORD 1. This handbook is approved for use by all Departments and Agencies of the Department of Defense (DoD). It was developed by the DoD with the assistance of the military departments, federal agencies, and industry and replaces in its entirety MIL-HDBK-338A. The handbook is written for reliability managers and engineers and provides guidance in developing and implementing a sound reliability program for all types of products. This Handbook is for guidance only. This Handbook cannot be cited as a requirement. If it is, the contractor does not have to comply. Reliability is a discipline that continues to increase in importance as systems become more complex, support costs increase, and defense budgets decrease. Reliability has been a recognized performance factor for at least 50 years. During World War II, the V-1 missile team, led by Dr. Wernher von Braun, developed what was probably the first reliability model. The model was based on a theory advanced by Eric Pieruschka that if the probability of survival of an element is 1/x, then the probability that a set of n identical elements will survive is (1/x)n . The formula derived from this theory is sometimes called Lusser’s law (Robert Lusser is considered a pioneer of reliability) but is more frequently known as the formula for the reliability of a series system: Rs = R1 x R2 x . . x Rn. Despite the long gestation period for reliability, achieving the high levels needed in military systems is too often an elusive goal. System complexity, competing performance requirements, the rush to incorporate promising but immature technologies, and the pressures of acquisition budget and schedule contribute to this elusiveness. In the commercial sector, high levels of reliability are also necessary. Recently, American products once shunned in favor of foreign alternatives have made or are making a comeback. This shift in consumer preferences is directly attributable to significant improvements in the reliability and quality of the American products. Noting these improvements, and facing a shrinking defense budget, the Department of Defense began the process of changing its acquisition policies to buy more commercial off-the-shelf products and to use commercial specifications and standards. The objective is to capitalize on the “best practices” that American business has developed or adopted, primarily in response to foreign competitive pressures. When combined with the knowledge and expertise of military contractors in building complex and effective military systems (soundly demonstrated during the conflict with Iraq), it is hoped that these commercial practices will allow the Department of Defense to acquire world-class systems on time and within budget.

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MIL-HDBK-338B FOREWORD 6. The information in this Handbook reflects the move within the military to incorporate best commercial practices and the lessons learned over many years of acquiring weapon systems “by the book”. Military as well as commercial standards and handbooks are cited for reference because they are familiar to both military and commercial companies. Many of the military documents are being rescinded, so copies may be difficult to obtain. For those who have copies or can obtain them, the military documents provide a wealth of valuable information. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be useful in improving this document should be addressed to: Air Force Research Laboratory/IFTB, 525 Brooks Road, Rome, NY 13441-4505. Comments should be submitted using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 1.0 SCOPE....................................................................................................................... 1.1 Introduction................................................................................................................ 1.2 Application................................................................................................................. 1.3 Organization............................................................................................................... 2 .0 2.1 2.2 3.0 3.1 3.2 3.3 4.0 4.1 4.2 4.3 4.4 4.5 5 .0 5.1 5.2 5.3 REFERENCED DOCUMENTS................................................................................ Government Documents ............................................................................................ 2.1.1 Specifications, Standards and Handbooks ................................................. Other Referenced Documents.................................................................................... DEFINITIONS OF TERMS AND ACRONYMS AND ABBREVIATIONS.......... Introduction ............................................................................................................... Definitions ................................................................................................................ List of Abbreviations and Acronyms......................................................................... GENERAL STATEMENTS ..................................................................................... Introduction and Background ................................................................................... The System Engineering Process .............................................................................. 4.2.1 Systems Engineering and IPTs .................................................................. 4.2.2 The Four Steps of Systems Engineering ................................................... System Effectiveness ................................................................................................ 4.3.1 R/M Considerations in System Effectiveness ........................................... Factors Influencing System Effectiveness ................................................................ 4.4.1 Equipment of New Design ........................................................................ 4.4.2 Interrelationships Among Various System Properties .............................. Optimization of System Effectiveness ...................................................................... RELIABILITY/MAINTAINABILITY/AVAILABILITY THEORY ..................... Introduction ............................................................................................................... Reliability Theory ..................................................................................................... 5.2.1 Basic Concepts .......................................................................................... Statistical Distributions Used in Reliability Models ................................................. 5.3.1 Continuous Distributions .......................................................................... 5.3.1.1 Normal (or Gaussian) Distribution ........................................... 5.3.2 Examples of Reliability Calculations Using the Normal Distribution....... 5.3.2.1 Microwave Tube Example ....................................................... 5.3.2.2 Mechanical Equipment Example .............................................. 5.3.3 Lognormal Distribution ............................................................................. 5.3.3.1 Fatigue Failure Example .......................................................... Page 1-1 1-1 1-1 1-1 2-1 2-1 2-1 2-3 3-1 3-1 3-1 3-21 4-1 4-1 4-2 4-3 4-3 4-7 4-8 4-8 4-8 4-9 4-11 5-1 5-1 5-1 5-2 5-8 5-8 5-8 5-14 5-14 5-15 5-16 5-17

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 5.3.4 Exponential Distribution ........................................................................... 5.3.4.1 Airborne Fire Control System Example ................................... 5.3.4.2 Computer Example ................................................................... 5.3.5 Gamma Distribution .................................................................................. 5.3.5.1 Missile System Example .......................................................... 5.3.6 Weibull Distribution .................................................................................. 5.3.6.1 Example of Use of Weibull Distribution .................................. 5.3.7 Discrete Distributions ................................................................................ 5.3.7.1 Binomial Distribution ............................................................... 5.3.7.1.1 Quality Control Example ......................................................... 5.3.7.1.2 Reliability Example ................................................................. 5.3.8 Poisson Distribution .................................................................................. 5.3.8.1 Example With Permissible Number of Failures ....................... Failure Modeling ....................................................................................................... 5.4.1 Typical Failure Rate Curve ....................................................................... 5.4.2 Reliability Modeling of Simple Structures ................................................ 5.4.2.1 Series Configuration ................................................................. 5.4.2.2 Parallel Configuration .............................................................. 5.4.2.3 K-Out-Of-N Configuration ....................................................... Bayesian Statistics in Reliability Analysis ............................................................... 5.5.1 Bayes’ Theorem ........................................................................................ 5.5.1.1 Bayes’ Example (Discrete Distribution) .................................. 5.5.1.2 Bayes’ Example (Continuous Distribution) ............................. Maintainability Theory ............................................................................................. 5.6.1 Basic Concepts .......................................................................................... 5.6.2 Statistical Distributions Used in Maintainability Models ......................... 5.6.2.1 Lognormal Distribution ............................................................ 5.6.2.1.1 Ground Electronic System Maintainability Analysis Example ........................................................... 5.6.2.2 Normal Distribution ................................................................. 5.6.2.2.1 Equipment Example .............................................. 5.6.2.3 Exponential Distribution .......................................................... 5.6.2.3.1 Computer Example ................................................ 5.6.2.4 Exponential Approximation ..................................................... Availability Theory ................................................................................................... 5.7.1 Basic Concepts .......................................................................................... 5.7.2 Availability Modeling (Markov Process Approach) ................................. 5.7.2.1 Single Unit Availability Analysis (Markov Process Approach) ..................................................... Page 5-17 5-18 5-18 5-19 5-21 5-22 5-23 5-24 5-24 5-24 5-25 5-26 5-27 5-28 5-28 5-30 5-31 5-32 5-35 5-37 5-38 5-39 5-42 5-44 5-45 5-48 5-49 5-51 5-63 5-65 5-67 5-68 5-70 5-70 5-72 5-73 5-75

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 5.8 R&M Trade-Off Techniques .................................................................................... 5.8.1 Reliability vs Maintainability..................................................................... 5.9 References For Section 5 .......................................................................................... 6 .0 6.1 6.2 RELIABILITY SPECIFICATION, ALLOCATION, MODELING AND PREDICTION ........................................................................................................... Introduction ............................................................................................................... Reliability Specification ........................................................................................... 6.2.1 Methods of Specifying the Reliability Requirement.................................. 6.2.2 Description of Environment and/or Use Conditions ................................. 6.2.3 Time Measure or Mission Profile ............................................................. 6.2.4 Clear Definition of Failure ........................................................................ 6.2.5 Description of Method(s) for Reliability Demonstration .......................... Reliability Apportionment/Allocation ...................................................................... 6.3.1 Introduction ............................................................................................... 6.3.2 Equal Apportionment Technique .............................................................. 6.3.3 ARINC Apportionment Technique (Ref. [6]) ........................................... 6.3.4 Feasibility-Of-Objectives Technique (Ref. [7]) ........................................ 6.3.5 Minimization of Effort Algorithm ............................................................ Reliability Modeling and Prediction ......................................................................... 6.4.1 Introduction ............................................................................................... 6.4.2 General Procedure ..................................................................................... 6.4.2.1 Item Definition ......................................................................... 6.4.2.2 Service Use Profile ................................................................... 6.4.2.3 Reliability Block Diagrams ...................................................... 6.4.2.4 Mathematical/Simulation Models ............................................ 6.4.2.5 Part Description ........................................................................ 6.4.2.6 Environmental Data .................................................................. 6.4.2.7 Stress Analysis ......................................................................... 6.4.2.8 Failure Distributions ................................................................. 6.4.2.9 Failure Rates ............................................................................. 6.4.2.10 Item Reliability ......................................................................... 6.4.3 Tailoring Reliability Models and Predictions ........................................... 6.4.4 Reliability Modeling ................................................................................. 6.4.4.1 Reliability Block Diagrams ...................................................... 6.4.4.2 Reliability Modeling Methods .................................................. 6.4.4.2.1 Conventional Probability Modeling Method ......... 6.4.4.2.1.1 Series Model ................................................... 6.4.4.2.1.2 Parallel Models ............................................... 6.4.4.2.1.3 Series-Parallel Models ................................... 6.4.4.2.2 Boolean Truth Table Modeling Method ................ Page 5-83 5-83 5-88 6-1 6-1 6-1 6-1 6-3 6-5 6-6 6-7 6-7 6-7 6-10 6-11 6-13 6-16 6-19 6-19 6-21 6-22 6-22 6-24 6-24 6-24 6-24 6-24 6-25 6-25 6-25 6-25 6-26 6-26 6-29 6-29 6-29 6-30 6-32 6-33

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 6.4.4.2.3 Logic Diagram Modeling Method ......................... 6.4.4.2.4 Complex System Modeling Methods .................... 6.4.4.2.4.1 Markov Modeling (Ref. [9]) .......................... 6.4.4.2.4.2 Monte Carlo Simulation Method ................... 6.4.5 Reliability Prediction ................................................................................ 6.4.5.1 General ..................................................................................... 6.4.5.2 Mathematical Models for Reliability Prediction ...................... 6.4.5.3 Reliability Prediction Methods ................................................. 6.4.5.3.1 Similar Item Prediction Method ............................ 6.4.5.3.2 Parts Count Prediction Method ............................. 6.4.5.3.3 Parts Stress Analysis Prediction Method .............. 6.4.5.3.3.1 Stress Analysis Techniques ............................ 6.4.5.3.3.2 Sample Calculation ........................................ 6.4.5.3.3.3 Modification for Non-Exponential Failure Densities (General Case) ....................................... 6.4.5.3.3.4 Nonoperating Failure Rates ............................ 6.4.5.3.4 Reliability Physics Analysis (Ref. [17] and [18]) .... 6.4.5.4 Computer Aided Reliability Prediction .................................... Step-By-Step Procedure for Performing Reliability Prediction and Allocation ....... References for Section 6 ........................................................................................... RELIABILITY ENGINEERING DESIGN GUIDELINES ..................................... Introduction ............................................................................................................... Parts Management ..................................................................................................... 7.2.1 Establishing a Preferred Parts List (PPL) .................................................. 7.2.2 Vendor and Device Selection .................................................................... 7.2.2.1 Critical Devices/Technology/Vendors ..................................... 7.2.2.1.1 ASIC Devices ........................................................ 7.2.2.1.2 GaAs and MMIC Devices ..................................... 7.2.2.2 Plastic Encapsulated Microcircuits (PEMs) ............................. 7.2.2.3 Hidden Hybrids ........................................................................ 7.2.2.4 Device Specifications ............................................................... 7.2.2.5 Screening .................................................................................. 7.2.2.6 Part Obsolescence and Diminishing Manufacturer Sources (DMS) ......................................................................... 7.2.2.7 Failure Reporting, Analysis, And Corrective Action System (FRACAS) ................................................................... 7.2.3 Design for Reliability ................................................................................ 7.2.3.1 Electronic Part Reliability Assessment / Life Analysis ............ 7.2.4 Design for Manufacturability .................................................................... Page 6-38 6-41 6-41 6-42 6-44 6-46 6-48 6-50 6-50 6-52 6-54 6-57 6-59 6-63 6-66 6-68 6-71 6-71 6-72 7-1 7-1 7-2 7-3 7-5 7-8 7-9 7-9 7-10 7-10 7-11 7-12 7-12 7-15 7-15 7-16 7-19

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 7.2.5 Parts Management Plan Evaluation Criteria ............................................. 7.2.5.1 Quality Improvement Program ................................................. 7.2.5.2 Quality Assurance .................................................................... 7.2.5.2.1 Part Qualification .................................................. 7.2.5.2.2 Production Quality Assurance ............................... 7.2.5.3 Assembly Processes ................................................................. 7.2.5.4 Design Criteria ......................................................................... Derating .................................................................................................................... 7.3.1 Electronic Part Derating ............................................................................ 7.3.2 Derating of Mechanical and Structural Components ................................ Reliable Circuit Design ............................................................................................. 7.4.1 Transient and Overstress Protection .......................................................... 7.4.1.1 On-Chip Protection Networks .................................................. 7.4.1.2 Metal Oxide Varistors (MOVs) ................................................ 7.4.1.3 Protective Diodes ..................................................................... 7.4.1.4 Silicon Controlled Rectifier Protection .................................... 7.4.1.5 Passive Component Protection ................................................. 7.4.1.6 Protective Devices Summary ................................................... 7.4.1.7 Protection Design For Parts, Assemblies and Equipment ........ 7.4.1.8 Printed Wiring Board Layout ................................................... 7.4.1.9 Shielding ................................................................................... 7.4.1.10 Grounding ................................................................................. 7.4.1.11 Protection With MOVs ............................................................. 7.4.1.12 Protection With Diodes ............................................................ 7.4.2 Parameter Degradation and Circuit Tolerance Analysis ........................... 7.4.3 Computer Aided Circuit Analysis ............................................................. 7.4.3.1 Advantages of Computer Aided Circuit Analysis/Simulation . 7.4.3.2 Limitations of Computer-Aided Circuit Analysis/Simulation Programs ................................................................................... 7.4.3.3 The Personal Computer (PC) as a Circuit Analysis Tool ......... 7.4.4 Fundamental Design Limitations .............................................................. 7.4.4.1 The Voltage Gain Limitation ................................................... 7.4.4.2 Current Gain Limitation Considerations .................................. 7.4.4.3 Thermal Factors ........................................................................ Fault Tolerant Design ............................................................................................... 7.5.1 Redundancy Techniques ........................................................................... 7.5.1.1 Impact on Testability ................................................................ 7.5.2 Reliability Role in the Fault Tolerant Design Process .............................. 7.5.2.1 Fault Tolerant Design Analysis ................................................ Page 7-20 7-20 7-20 7-21 7-24 7-26 7-28 7-30 7-30 7-32 7-38 7-38 7-40 7-42 7-43 7-43 7-44 7-47 7-48 7-49 7-50 7-52 7-54 7-57 7-62 7-70 7-71 7-71 7-71 7-74 7-75 7-78 7-79 7-80 7-81 7-81 7-84 7-86

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 7.5.3 Redundancy as a Design Technique .......................................................... 7.5.3.1 Levels of Redundancy .............................................................. 7.5.3.2 Probability Notation for Redundancy Computations ............... 7.5.3.3 Redundancy Combinations ....................................................... 7.5.4 Redundancy in Time Dependent Situations .............................................. 7.5.5 Redundancy Considerations in Design ..................................................... 7.5.5.1 Partial Redundancy ................................................................... 7.5.5.2 Operating Standby Redundancy ............................................... 7.5.5.2.1 Two Parallel Elements .......................................... 7.5.5.2.2 Three Parallel Elements ........................................ 7.5.5.2.3 Voting Redundancy ............................................... 7.5.5.3 Inactive Standby Redundancy .................................................. 7.5.5.4 Dependent Failure Probabilities ............................................... 7.5.5.5 Optimum Allocation of Redundancy ....................................... 7.5.6 Reliability Analysis Using Markov Modeling .......................................... 7.5.6.1 Introduction .............................................................................. 7.5.6.2 Markov Theory ......................................................................... 7.5.6.3 Development of the Markov Model Equation .......................... 7.5.6.4 Markov Model Reduction Techniques ..................................... 7.5.6.5 Application of Coverage to Markov Modeling ........................ 7.5.6.6 Markov Conclusions ................................................................. Environmental Design .............................................................................................. 7.6.1 Environmental Strength ............................................................................. 7.6.2 Designing for the Environment ................................................................. 7.6.3 Temperature Protection ............................................................................. 7.6.4 Shock and Vibration Protection ................................................................ 7.6.5 Moisture Protection ................................................................................... 7.6.6 Sand and Dust Protection .......................................................................... 7.6.7 Explosion Proofing .................................................................................... 7.6.8 Electromagnetic Radiation Protection ....................................................... 7.6.9 Nuclear Radiation ...................................................................................... 7.6.10 Avionics Integrity Program (AVIP) .......................................................... 7.6.10.1 MIL-STD-1670: Environmental Criteria and Guidelines for Air Launched Weapons ...................................................... Human Performance Reliability ............................................................................... 7.7.1 Introduction ............................................................................................... 7.7.2 Reliability, Maintainability, and Availability Parameters for Human - Machine Systems ....................................................................... 7.7.3 Allocating System Reliability to Human Elements ................................. 7.7.3.1 Qualitative Allocation ............................................................. 7.7.3.2 Quantitative Allocation ........................................................... Page 7-88 7-92 7-93 7-94 7-96 7-98 7-105 7-109 7-109 7-111 7-112 7-113 7-117 7-118 7-119 7-119 7-121 7-123 7-125 7-127 7-128 7-128 7-128 7-129 7-140 7-142 7-144 7-145 7-146 7-147 7-149 7-151 7-153 7-159 7-159 7-161 7-165 7-165 7-167

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 7.7.4 7.7.5 Sources of Human Performance Reliability Data ..................................... Tools for Designing Man-Machine Systems ............................................. 7.7.5.1 Task Analysis ........................................................................... 7.7.5.2 General Design Tools ............................................................... 7.7.5.3 Computer-Based Design Tools ............................................... 7.7.5.3.1 Parametric Design Tools ....................................... 7.7.5.3.2 Interface Design Tools .......................................... 7.7.5.3.3 Work Space Design Tools ..................................... 7.7.6 Reliability Prediction for Human-Machine Systems ................................ 7.7.6.1 Probability Compounding ........................................................ 7.7.6.2 Stochastic Models ..................................................................... 7.7.6.3 Digital Simulation .................................................................... 7.7.6.4 Expert Judgment Techniques ................................................... 7.7.7 Verification of Human Performance Reliability ....................................... Failure Mode and Effects Analysis (FMEA) ............................................................ 7.8.1 Introduction ............................................................................................... 7.8.2 Phase 1 ...................................................................................................... 7.8.3 Phase 2 ...................................................................................................... 7.8.4 Example ..................................................................................................... 7.8.5 Risk Priority Number ................................................................................ 7.8.5.1 Instituting Corrective Action .................................................... 7.8.6 Computer Aided FMEA ............................................................................ 7.8.7 FMEA Summary ....................................................................................... Fault Tree Analysis ................................................................................................... 7.9.1 Discussions of FTA Methods .................................................................... Sneak Circuit Analysis (SCA) .................................................................................. 7.10.1 Definition of Sneak Circuit ........................................................................ 7.10.2 SCA: Definition and Traditional Techniques ........................................... 7.10.3 New SCA Techniques ............................................................................... 7.10.4 Examples of Categories of SNEAK Circuits ............................................ 7.10.5 SCA Methodology ..................................................................................... 7.10.5.1 Network Tree Production ......................................................... 7.10.5.2 Topological Pattern Identification ............................................ 7.10.5.3 Clue Application ....................................................................... 7.10.6 Software Sneak Analysis ........................................................................... 7.10.7 Integration of Hardware/Software Analysis .............................................. 7.10.8 Summary ................................................................................................... Design Reviews ........................................................................................................ 7.11.1 Introduction and General Information ....................................................... 7.11.2 Informal Reliability Design Review ......................................................... 7.11.3 Formal Design Reviews ............................................................................ Page 7-169 7-172 7-173 7-173 7-175 7-176 7-176 7-176 7-177 7-178 7-183 7-184 7-186 7-187 7-187 7-187 7-190 7-201 7-203 7-206 7-209 7-209 7-210 7-210 7-221 7-222 7-222 7-223 7-224 7-225 7-229 7-229 7-229 7-231 7-231 7-234 7-235 7-236 7-236 7-239 7-240

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 7.11.4 Design Review Checklists ......................................................................... 7.12 Design for Testability ............................................................................................... 7.12.1 Definition of Testability and Related Terms ............................................. 7.12.2 Distinction between Testability and Diagnostics ...................................... 7.12.3 Designing for Testability ........................................................................... 7.12.4 Developing a Diagnostic Capability ......................................................... 7.12.5 Designing BIT ........................................................................................... 7.12.6 Testability Analysis ................................................................................... 7.12.6.1 Dependency Analysis ............................................................... 7.12.6.1.1 Dependency Analysis Tools ................................. 7.12.6.2 Other Types of Testability Analyses ........................................ 7.13 System Safety Program ............................................................................................. 7.13.1 Introduction ............................................................................................... 7.13.2 Definition of Safety Terms and Acronyms ............................................... 7.13.3 Program Management and Control Elements ........................................... 7.13.3.1 System Safety Program ............................................................ 7.13.3.2 System Safety Program Plan .................................................... 7.13.3.3 Integration/Management of Associate Contractors, Subcontractors, and Architect and Engineering Firms ............ 7.13.3.4 System Safety Program Reviews/Audits .................................. 7.13.3.5 System Safety Group/System Safety Working Group Support ..................................................................................... 7.13.3.6 Hazard Tracking and Risk Resolution ...................................... 7.13.3.7 System Safety Progress Summary ............................................ 7.13.4 Design and Integration Elements .............................................................. 7.13.4.1 Preliminary Hazard List ........................................................... 7.13.4.2 Preliminary Hazard Analysis .................................................... 7.13.4.3 Safety Requirements/Criteria Analysis .................................... 7.13.4.4 Subsystem Hazard Analysis ..................................................... 7.13.4.5 System Hazard Analysis ........................................................... 7.13.4.6 Operating and Support Hazard Analysis .................................. 7.13.4.7 Occupational Health Hazard Assessment ................................. 7.13.5 Design Evaluation Elements ..................................................................... 7.13.5.1 Safety Assessment .................................................................... 7.13.5.2 Test and Evaluation Safety ....................................................... 7.13.5.3 Safety Review of Engineering Change Proposals and Requests for Deviation/Waiver ................................................ Page 7-246 7-250 7-251 7-251 7-251 7-255 7-256 7-257 7-258 7-260 7-260 7-262 7-262 7-267 7-268 7-268 7-268 7-269 7-269 7-269 7-269 7-269 7-269 7-269 7-270 7-270 7-270 7-270 7-270 7-270 7-270 7-270 7-271 7-271

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 7.13.6 Compliance and Verification .................................................................... 7.13.6.1 Safety Verification ................................................................... 7.13.6.2 Safety Compliance Assessment ................................................ 7.13.6.3 Explosive Hazard Classification and Characteristics Data ...... 7.13.6.4 Explosive Ordinance Disposal Source Data ............................. 7.13.7 Tailoring Guidelines .................................................................................. Finite Element Analysis ............................................................................................ 7.14.1 Introduction and General Information ....................................................... 7.14.2 Finite Element Analysis Application ........................................................ 7.14.3 Finite Element Analysis Procedure ........................................................... 7.14.4 Applications .............................................................................................. 7.14.5 Limitations ................................................................................................. References for Section 7 ............................................................................................ Page 7-271 7-271 7-271 7-271 7-271 7-272 7-272 7-272 7-272 7-276 7-278 7-278 7-279 8-1 8-1 8-2 8-2 8-3 8-7 8-7 8-7 8-9 8-10 8-10 8-13 8-21 8-21 8-22 8-29 8-31 8-33 8-36 8-37 8-39 8-43 8-50

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RELIABILITY DATA COLLECTION AND ANALYSIS, DEMONSTRATION AND GROWTH ....................................................................................................... Introduction ............................................................................................................... Failure Reporting, Analysis, and Corrective Action System (FRACAS) and Failure Review Board (FRB) .................................................................................... 8.2.1 Failure Reporting, Analysis and Corrective Action System (FRACAS) .. 8.2.1.1 Closed Loop Failure Reporting/Corrective Actions System .... 8.2.1.2 Failure Reporting Systems ....................................................... 8.2.1.3 Failure Reporting Forms .......................................................... 8.2.1.4 Data Collection and Retention ................................................. 8.2.2 Failure Review Board ................................................................................ Reliability Data Analysis .......................................................................................... 8.3.1 Graphical Methods .................................................................................... 8.3.1.1 Examples of Graphical Methods .............................................. 8.3.2 Statistical Analysis .................................................................................... 8.3.2.1 Introduction .............................................................................. 8.3.2.2 Treatment of Failure Data ........................................................ 8.3.2.3 Reliability Function (Survival Curves) .................................... 8.3.2.3.1 Computation of Theoretical Exponential Reliability Function ............................................... 8.3.2.3.2 Computation For Normal Reliability Function ..... 8.3.2.4 Censored Data .......................................................................... 8.3.2.5 Confidence Limits and Intervals .............................................. 8.3.2.5.1 Confidence Limits - Normal Distribution ............. 8.3.2.5.2 Confidence Limits - Exponential Distribution ...... 8.3.2.5.3 Confidence-Interval Estimates for the Binomial Distribution ............................................

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section Tests for Validity of the Assumption Of A Theoretical Reliability Parameter Distribution ............................................ 8.3.2.6.1 Kolmogorov-Smirnov (K-S) Goodness-of-Fit Test (also called “d” test) ...................................... 8.3.2.6.2 Chi-Square Goodness-of-Fit Test ......................... 8.3.2.6.3 Comparison of K-S and Chi-Square Goodness-of-Fit Tests ........................................... Reliability Demonstration ......................................................................................... 8.4.1 Introduction ............................................................................................... 8.4.2 Attributes and Variables ............................................................................ 8.4.3 Fixed Sample and Sequential Tests ........................................................... 8.4.4 Determinants of Sample Size .................................................................... 8.4.5 Tests Designed Around Sample Size ........................................................ 8.4.6 Parameterization of Reliability .................................................................. 8.4.7 Instructions on the Use of Reliability Demonstration Test Plans ............. 8.4.7.1 Attributes Demonstration Tests ................................................ 8.4.7.1.1 Attributes Plans for Small Lots ............................. 8.4.7.1.2 Attributes Plans for Large Lots ............................. 8.4.7.2 Attributes Demonstration Test Plans for Large Lots, Using the Poisson Approximation Method .............................. 8.4.7.3 Attributes Sampling Using ANSI/ASQC Z1.4-1993 ............... 8.4.7.4 Sequential Binomial Test Plans ............................................... 8.4.7.5 Variables Demonstration Tests ................................................ 8.4.7.5.1 Time Truncated Demonstration Test Plans ........... 8.4.7.5.1.1 Exponential Distribution (H-108) .................. 8.4.7.5.1.2 Normal Distribution ....................................... 8.4.7.5.1.3 Weibull Distribution (TR-3, TR-4, TR-6) ...... 8.4.7.5.2 Failure Truncated Tests ......................................... 8.4.7.5.2.1 Exponential Distribution (MIL-HDBK-H108) ........................................................ 8.4.7.5.2.2 Normal Distribution, ! Known ...................... 8.4.7.5.2.3 Normal Distribution, ! Unknown (MIL-STD-414) .............................................................. 8.4.7.5.2.4 Weibull Distribution ....................................... 8.4.7.5.3 Sequential Tests .................................................... 8.4.7.5.3.1 Exponential Distribution (MIL-HDBK-781) ................................................. 8.4.7.5.3.2 Normal Distribution ....................................... 8.4.7.6 Interference Demonstration Tests ............................................ 8.4.7.7 Bayes Sequential Tests ............................................................. 8.4.8 Reliability Demonstration Summary ......................................................... 8.3.2.6 Page 8-52 8-53 8-60 8-67 8-68 8-68 8-75 8-75 8-75 8-76 8-76 8-76 8-77 8-77 8-81 8-84 8-87 8-89 8-93 8-93 8-93 8-95 8-100 8-103 8-103 8-105 8-110 8-113 8-116 8-116 8-119 8-123 8-127 8-131

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 8.5 Reliability Growth .................................................................................................... 8.5.1 Reliability Growth Concept ...................................................................... 8.5.2 Reliability Growth Modeling .................................................................... 8.5.2.1 Application Example ................................................................ 8.5.3 Comparison of the Duane and AMSAA Growth Models ......................... 8.5.3.1 Other Growth Models ............................................................... 8.5.4 Reliability Growth Testing ........................................................................ 8.5.4.1 When Reliability Growth Testing is Performed ....................... 8.5.4.2 Reliability Growth Approach ................................................... 8.5.4.3 Economics of Reliability Growth Testing ................................ 8.5.5 Reliability Growth Management ............................................................... 8.5.5.1 Management of the Reliability Growth Process ....................... 8.5.5.2 Information Sources That Initiate Reliability Growth ............. 8.5.5.3 Relationships Among Growth Information Sources ................ 8.6 Summary of the Differences Between Reliability Growth Testing and Reliability Demonstration Testing ........................................................................... 8.7 Accelerated Testing .................................................................................................. 8.7.1 Accelerated Life Testing ........................................................................... 8.7.2 Accelerated Stress Testing ........................................................................ 8.7.3 Equipment Level Accelerated Tests .......................................................... 8.7.4 Component Level Accelerated Test .......................................................... 8.7.5 Accelerated Test Models ........................................................................... 8.7.5.1 The Inverse Power Law Acceleration Model ........................... 8.7.5.2 The Arrhenius Acceleration Model .......................................... 8.7.5.3 Miner’s Rule - Fatigue Damage ............................................... 8.7.6 Advanced Concepts In Accelerated Testing ............................................. 8.7.6.1 Step Stress Profile Testing ....................................................... 8.7.6.2 Progressive Stress Profile Testing ............................................ 8.7.6.3 HALT Testing .......................................................................... 8.7.6.4 HASS Testing ........................................................................... 8.7.6.5 HAST (Highly Accelerated Temperature and Humidity Stress Test) ............................................................................... 8.7.7 Accelerated Testing Data Analysis and Corrective Action Caveats ......... 8.8 References for Section 8 ........................................................................................... 9.0 9.1 9.2 SOFTWARE RELIABILITY ................................................................................... Introduction ............................................................................................................... Software Issues ......................................................................................................... Page 8-132 8-132 8-135 8-142 8-144 8-147 8-147 8-147 8-148 8-153 8-154 8-154 8-156 8-157 8-159 8-160 8-162 8-162 8-162 8-163 8-163 8-164 8-165 8-167 8-169 8-170 8-171 8-171 8-173 8-174 8-174 8-176 9-1 9-1 9-4

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 9.3 Software Design ........................................................................................................ 9.3.1 Preliminary Design .................................................................................... 9.3.1.1 Develop the Architecture .......................................................... 9.3.1.2 Physical Solutions .................................................................... 9.3.1.3 External Characteristics ............................................................ 9.3.1.4 System Functional Decomposition ........................................... 9.3.2 Detailed Design ......................................................................................... 9.3.2.1 Design Examples ...................................................................... 9.3.2.2 Detailed Design Tools .............................................................. 9.3.2.3 Software Design and Coding Techniques ................................ 9.4 Software Design and Development Process Model .................................................. 9.4.1 Ad Hoc Software Development ................................................................ 9.4.2 Waterfall Model ........................................................................................ 9.4.3 Classic Development Model ..................................................................... 9.4.4 Prototyping Approach ............................................................................... 9.4.5 Spiral Model .............................................................................................. 9.4.6 Incremental Development Model .............................................................. 9.4.7 Cleanroom Model ...................................................................................... 9.5 Software Reliability Prediction and Estimation Models ........................................... 9.5.1 Prediction Models ..................................................................................... 9.5.1.1 In-house Historical Data Collection Model .............................. 9.5.1.2 Musa’s Execution Time Model ................................................ 9.5.1.3 Putnam’s Model ....................................................................... 9.5.1.4 Rome Laboratory Prediction Model: RL-TR-92-52 (Ref. [16]) ................................................................................. 9.5.1.5 Rome Laboratory Prediction Model: RL-TR-92-15 (Ref. [17]) ................................................................................. 9.5.2 Estimation Models .................................................................................... 9.5.2.1 Exponential Distribution Models .............................................. 9.5.2.2 Weibull Distribution Model (Ref. [19]) ................................... 9.5.2.3 Bayesian Fault Rate Estimation Model .................................... 9.5.2.4 Test Coverage Reliability Metrics ............................................ 9.5.3 Estimating Total Number of Faults Using Tagging .................................. 9.6 Software Reliability Allocation ................................................................................ 9.6.1 Equal Apportionment Applied to Sequential Software CSCIs ................. 9.6.2 Equal Apportionment Applied to Concurrent Software CSCIs ................ 9.6.3 Allocation Based on Operational Criticality Factors ................................ 9.6.4 Allocation Based on Complexity Factors .................................................. Page 9-12 9-12 9-13 9-13 9-14 9-15 9-15 9-15 9-16 9-16 9-17 9-19 9-19 9-20 9-22 9-24 9-26 9-28 9-30 9-31 9-31 9-32 9-33 9-35 9-38 9-40 9-40 9-46 9-46 9-48 9-49 9-51 9-53 9-54 9-54 9-56

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 9.7 Software Testing ....................................................................................................... 9.7.1 Module Testing ......................................................................................... 9.7.2 Integration Testing .................................................................................... 9.7.3 System Testing .......................................................................................... 9.7.4 General Methodology for Software Failure Data Analysis ....................... 9.8 Software Analyses .................................................................................................... 9.8.1 Failure Modes ............................................................................................ 9.8.2 Failure Effects ........................................................................................... 9.8.3 Failure Criticality ...................................................................................... 9.8.4 Fault Tree Analysis ................................................................................... 9.8.5 Failure Modes and Effects Analysis .......................................................... 9.9 References ................................................................................................................. 10.0 10.1 SYSTEMS RELIABILITY ENGINEERING .......................................................... Introduction ............................................................................................................... 10.1.1 Commercial-Off-The-Shelf (COTS) and Nondevelopmental Item (NDI) Considerations ................................................................................ 10.1.2 COTS/NDI as the End Product ................................................................. 10.1.3 COTS/NDI Integrated with Other Items ................................................... 10.1.4 Related COTS/NDI Issues ........................................................................ System Effectiveness Concepts ................................................................................ 10.2.1 The ARINC Concept of System Effectiveness (Ref. [1]) ......................... 10.2.2 The Air Force (WSEIAC) Concept (Ref. [2]) .......................................... 10.2.3 The Navy Concept of System Effectiveness (Ref. [4]) ............................. 10.2.4 An Illustrative Model of a System Effectiveness Calculation .................. System R&M Parameters .......................................................................................... 10.3.1 Parameter Translation Models .................................................................. 10.3.1.1 Reliability Adjustment Factors ................................................. 10.3.1.2 Reliability Prediction of Dormant Products ............................. 10.3.2 Operational Parameter Translation ............................................................ 10.3.2.1 Parameter Definitions ............................................................... 10.3.2.2 Equipment Operating Hour to Flight Hour Conversion ........... 10.3.3 Availability, Operational Readiness, Mission Reliability, and Dependability - Similarities and Differences ............................................ System, R&M Modeling Techniques ....................................................................... 10.4.1 Availability Models ................................................................................... 10.4.1.1 Model A - Single Unit System (Point Availability) ................. 10.4.1.2 Model B - Average or Interval Availability ........................... 10.4.1.3 Model C - Series System with Repairable/Replaceable Units ......................................................................................... 10.4.1.4 Model D - Redundant Systems ............................................... Page 9-58 9-58 9-59 9-61 9-61 9-62 9-64 9-64 9-65 9-66 9-67 9-69 10-1 10-1 10-2 10-8 10-8 10-9 10-9 10-9 10-10 10-14 10-16 10-20 10-21 10-21 10-24 10-25 10-27 10-27 10-28 10-30 10-33 10-33 10-38 10-40 10-43

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Page 10.4.1.5 Model E - R&M Parameters Not Defined in Terms of Time ..................................................................................... 10-55 10.4.2 Mission Reliability and Dependability Models ......................................... 10-58 10.4.3 Operational Readiness Models .................................................................. 10-60 10.4.3.1 Model A - Based Upon Probability of Failure During Previous Mission and Probability of Repair Before Next Mission Demand ....................................................................... 10-61 10.4.3.2 Model B - Same As Model A Except Mission Duration Time, t is Probabilistic .............................................................. 10-63 10.4.3.3 Model C - Similar To Model A But Includes Checkout Equipment Detectability ........................................................... 10-64 10.4.3.4 Model D - For a Population of N Systems ............................. 10-66 10.5 Complex Models ....................................................................................................... 10-73 10.6 Trade-off Techniques ................................................................................................ 10-74 10.6.1 General ...................................................................................................... 10-74 10.6.2 Reliability - Availability - Maintainability Trade-offs .............................. 10-75 10.7 Allocation of Availability, Failure and Repair Rates ............................................... 10-86 10.7.1 Availability Failure Rate and Repair Rate Allocation for Series Systems ..................................................................................................... 10-87 10.7.1.1 Case (1) ..................................................................................... 10-87 10.7.1.2 Case (2) ..................................................................................... 10-88 10.7.2 Failure and Repair Rate Allocations For Parallel Redundant Systems ..... 10-93 10.7.3 Allocation Under State-of-the-Art Constraints ......................................... 10-99 10.8 System Reliability Specification, Prediction and Demonstration ............................. 10-100 10.8.1 Availability Demonstration Plans ............................................................. 10-100 10.8.1.1 Fixed Sample Size Plans .......................................................... 10-101 10.8.1.2 Fixed-Time Sample Plans ........................................................ 10-104 10.9 System Design Considerations ................................................................................. 10-106 10.10 Cost Considerations .................................................................................................. 10-109 10.10.1 Life Cycle Cost (LCC) Concepts .............................................................. 10-109 10.11 References for Section 10 ......................................................................................... 10-117 11.0 11.1 11.2 PRODUCTION AND USE (DEPLOYMENT) R&M ............................................. 11-1 Introduction ............................................................................................................... 11-1 Production Reliability Control .................................................................................. 11-3 11.2.1 Quality Engineering (QE) and Quality Control (QC) ............................... 11-4 11.2.1.1 Quality System Requirements .................................................. 11-6 11.2.1.1.1 ISO 9000 .............................................................. 11-6 11.2.1.1.1.1 Comparing ISO 9000 to MIL-Q-9858 ......... 11-8 11.2.1.1.1.2 Why ISO 9000? ............................................ 11-9 11.2.1.2 Quality Control ......................................................................... 11-10 Section

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 11.2.2 Production Reliability Degradation Assessment & Control ..................... 11.2.2.1 Factors Contributing to Reliability Degradation During Production: Infant Mortality ..................................................... 11.2.2.2 Process Reliability Analysis ..................................................... 11.2.3 Application of Environmental Stress Screening (ESS) During Production to Reduce Degradation and Promote Growth ......................... 11.2.3.1 Part Level Screening ................................................................ 11.2.3.2 Screening at Higher Levels of Assembly ................................. 11.2.3.3 Screen Test Planning and Effectiveness ................................... 11.2.3.3.1 Environmental Stress Screening per MIL-HDBK-344 ............................................................. 11.2.3.3.2 Tri-Service ESS Guidelines .................................. 11.2.3.3.2.1 Types of Flaws to be Precipitated ................ 11.2.3.3.2.2 Levels of Assembly at which ESS May be Performed ....................... ................................... 11.2.3.3.2.3 Types and Severities of Stresses .................. 11.2.3.3.2.4 Failure Detection Measurements During Thermal Cycling and Random Vibration ........................ 11.2.3.3.2.5 Baseline ESS Profiles ................................... 11.2.3.3.2.6 Optimizing/Tailoring of ESS ....................... 11.2.4 Production Reliability Acceptance Testing (MIL-HDBK-781) ................ 11.2.5 Data Collection and Analysis (During Production) .................................. 11.2.6 Monitor/Control of Subcontractors and Suppliers .................................... 11.2.6.1 Major Subcontractor and Manufacturer Monitoring ................ 11.2.6.2 Establishing Vendor Capability and Program Reviews ........... 11.2.6.3 Supplier Monitoring ................................................................. Production Maintainability Control .......................................................................... Reliability and Quality During Shipment and Storage ............................................. 11.4.1 Factors Contributing to Reliability Degradation During Shipment & Storage .................................................................................. 11.4.2 Protection Methods ................................................................................... 11.4.3 Shipment and Storage Degradation Control (Storage Serviceability Standards) .................................................................................................. 11.4.3.1 Application of Cyclic Inspection During Storage to Assure Reliability and Material Readiness .......................... 11.4.4 Data Collection and Analysis (During Storage) ........................................ Operational R&M Assessment and Improvement .................................................... 11.5.1 Factors Contributing to R&M Degradation During Field Operation ........ 11.5.2 Maintenance Degradation Control (During Depot Storage) ..................... 11.5.3 Maintenance Documentation Requirements ............................................. 11.5.4 Data Collection and Analysis (During Field Deployment) ....................... Page 11-14 11-15 11-19 11-26 11-28 11-30 11-32 11-32 11-36 11-37 11-37 11-40 11-41 11-41 11-44 11-45 11-52 11-54 11-54 11-54 11-55 11-55 11-55 11-56 11-58 11-62 11-72 11-72 11-74 11-75 11-76 11-79 11-80

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section Page 11.5.5 System R&M Assessment ......................................................................... 11-82 11.5.6 System R&M Improvement ...................................................................... 11-85 11.6 References For Section 11 ........................................................................................ 11-87 12.0 12.1 RELIABILITY MANAGEMENT CONSIDERATIONS ........................................ Impacts of Acquisition Reform ................................................................................. 12.1.1 Acquisition Reform History ...................................................................... 12.1.1.1 Performance-based Specifications ........................................... 12.1.1.2 Other Standardization Documents ............................................ 12.1.1.3 Overall Acquisition Policy and Procedures .............................. 12.1.1.4 Impacts on Reliability Management ......................................... Reliability Program Management Issues .................................................................. Reliability Specification Requirements .................................................................... 12.3.1 Template for Preparing Reliability Section of Solicitation ....................... 12.3.2 Guidance for Selecting Sources ................................................................ Reliability Program Elements ................................................................................... Phasing of Reliability Program Activities ................................................................ 12.5.1 Reliability Activities by Life Cycle Phase ................................................ 12.5.1.1 Phase 0 - Concept Exploration ................................................. 12.5.1.2 Phase I - Program Definition and Risk Reduction ................... 12.5.1.3 Phase II - Engineering and Manufacturing Development ........ 12.5.1.4 Phase III - Production, Deployment, and Operational Support ..................................................................................... R&M Planning and Budgeting ................................................................................. 12.6.1 Conceptual Exploration Phase Planning ................................................... 12.6.2 Program Definition and Risk Reduction ................................................... 12.6.3 Engineering and Manufacturing Development (EMD) Phase Planning ... 12.6.4 Production, Deployment, and Operational Support Phase Planning ......... Trade-offs .................................................................................................................. 12.7.1 Concept Exploration Phase Trade-off Studies .......................................... 12.7.2 Program Definition and Risk Reduction Phase Trade-off Studies ............ 12.7.3 Trade-offs During Engineering Manufacturing Development (EMD), Production, Deployment and Operational Support Phases .......... Other Considerations ................................................................................................ 12.8.1 Software Reliability ................................................................................... 12.8.1.1 Requirements Definition .......................................................... 12.8.1.2 System Analysis ....................................................................... 12.8.1.3 Package Design ........................................................................ 12.8.1.4 Unit Design, Code and Debug .................................................. 12.8.1.5 Module Integration and Test .................................................... 12.8.1.6 System Integration and Test ..................................................... 12-1 12-1 12-1 12-1 12-3 12-4 12-4 12-5 12-6 12-7 12-15 12-17 12-19 12-20 12-22 12-22 12-23 12-24 12-25 12-26 12-26 12-27 12-28 12-28 12-29 12-30 12-31 12-32 12-32 12-35 12-35 12-37 12-37 12-37 12-38

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MIL-HDBK-338B TABLE OF CONTENTS TABLE OF CONTENTS Section 12.8.1.7 Acceptance Test ....................................................................... 12.8.1.8 Program Plan ............................................................................ 12.8.1.9 Specifications ........................................................................... 12.8.1.10 Data System .............................................................................. 12.8.1.11 Program Review ....................................................................... 12.8.1.12 Test Plan ................................................................................... 12.8.1.13 Technical Manuals ................................................................... 12.8.2 Cost Factors and Guidelines ...................................................................... 12.8.2.1 Design-To-Cost Procedures ..................................................... 12.8.2.2 Life Cycle Cost (LCC) Concepts ............................................. 12.8.3 Product Performance Agreements ............................................................. 12.8.3.1 Types of Product Performance Agreements ............................. 12.8.3.2 Warranty/Guarantee Plans ........................................................ 12.8.4 Reliability Program Requirements, Evaluation and Surveillance ............. 12.8.4.1 Reliability Program Requirements Based Upon the Type of Procurement .......................................................... 12.8.4.2 Reliability Program Evaluation and Surveillance .................... References for Section 12 ......................................................................................... Page 12-38 12-38 12-38 12-39 12-39 12-40 12-40 12-40 12-43 12-45 12-45 12-47 12-51 12-53 12-53 12-55 12-56

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES FIGURE 3-1: FIGURE 4.2-1: FIGURE 4.2-2: FIGURE 4.5-1: FIGURE 5.2-1: FIGURE 5.3-1: FIGURE 5.3-2: FIGURE 5.3-3: FIGURE 5.4-1: FIGURE 5.4-2: FIGURE 5.4-3: FIGURE 5.4-4: FIGURE 5.4-5: FIGURE 5.5-1: FIGURE 5.5-2: FIGURE 5.5-3: FIGURE 5.6-1: FIGURE 5.6-2: FIGURE 5.6-3: FIGURE 5.6-4: INTERVALS OF TIME ......................................................................... SYSTEM MANAGEMENT ACTIVITIES ............................................ FUNDAMENTAL SYSTEM PROCESS CYCLE.................................. FLOW DIAGRAM FOR A GENERAL OPTIMIZATION PROCESS ............................................................................................... SUMMARY OF BASIC RELIABILITY CONCEPTS ......................... SHAPES OF FAILURE DENSITY, RELIABILITY AND HAZARD RATE FUNCTIONS FOR COMMONLY USED CONTINUOUS DISTRIBUTIONS .................................................................................. SHAPES OF FAILURE DENSITY AND RELIABILITY FUNCTIONS OF COMMONLY USED DISCRETE DISTRIBUTIONS .................... FIVE CHANNEL RECEIVER WITH TWO FAILURES ALLOWED HAZARD RATE AS A FUNCTION OF AGE....................................... STABILIZATION OF FAILURE FREQUENCY ................................. SERIES CONFIGURATION ................................................................. PARALLEL CONFIGURATION .......................................................... COMBINED CONFIGURATION NETWORK .................................... SIMPLE PRIOR DISTRIBUTION ........................................................ SIMPLE POSTERIOR DISTRIBUTION .............................................. TREE DIAGRAM EXAMPLE .............................................................. BASIC METHODS OF MAINTAINABILITY MEASUREMENT ...... EXAMPLE MAINTAINABILITY FUNCTION DERIVED FROM TIME-TO-REPAIR DISTRIBUTION ................................................... PLOT OF THE LOGNORMAL OF THE TIMES-TO-RESTORE DATA GIVEN IN TABLE 5.6-5 IN TERMS OF THE STRAIGHT t’S ....................................................................................... PLOT OF THE LOGNORMAL PDF OF THE TIMES-TO-RESTORE DATA GIVEN IN TABLE 5.6-5 IN TERMS OF THE LOGARITHMS OF T, OR ln t’ ........................................................................................ PLOT OF THE MAINTAINABILITY FUNCTION FOR THE TIMES-TO-REPAIR DATA OF EXAMPLE 2 ..................................... EXPONENTIAL APPROXIMATION OF LOGNORMAL MAINTAINABILITY FUNCTIONS ..................................................... THE RELATIONSHIP BETWEEN INSTANTANEOUS, MISSION, AND STEADY STATE AVAILABILITIES AS A FUNCTION OF OPERATING TIME ............................................................................... MARKOV GRAPH FOR SINGLE UNIT .............................................. SINGLE UNIT AVAILABILITY WITH REPAIR................................. BLOCK DIAGRAM OF A SERIES SYSTEM ...................................... RELIABILITY-MAINTAINABILITY TRADE-OFFS ......................... Page 3-19 4-4 4-6 4-12 5-7 5-9 5-10 5-25 5-28 5-30 5-31 5-33 5-33 5-40 5-41 5-42 5-47 5-47 5-56 5-58 5-61 5-71 5-74 5-75 5-81 5-84 5-87

FIGURE 5.6-5: FIGURE 5.6-6: FIGURE 5.7-1: FIGURE 5.7-2: FIGURE 5.7-3: FIGURE 5.8-1: FIGURE 5.8-2

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES Page FIGURE 6.2-1: SATISFACTORY PERFORMANCE LIMITS FOR EXAMPLE RADAR .................................................................................................. FIGURE 6.2-2: TEMPERATURE PROFILE .................................................................. FIGURE 6.2-3: TYPICAL OPERATIONAL SEQUENCE FOR AIRBORNE FIRE CONTROL SYSTEM ................................................................... FIGURE 6.2-4: EXAMPLE DEFINITION OF RELIABILITY DESIGN REQUIREMENTS IN A SYSTEM SPECIFICATION FOR (1) AVIONICS, (2) MISSILE SYSTEM AND (3) AIRCRAFT ............ FIGURE 6.4-1: SERVICE USE EVENTS IN THE LOGISTIC AND OPERATIONAL CYCLES ................................................................................................. FIGURE 6.4-2: PROGRESSIVE EXPANSION OF RELIABILITY BLOCK DIAGRAM AS DESIGN DETAIL BECOMES KNOWN .................... FIGURE 6.4-3: RADAR SYSTEM HIERARCHY (PARTIAL LISTING) .................... FIGURE 6.4-4: SAMPLE RELIABILITY CALCULATION ......................................... FIGURE 7.2-1: VENDOR SELECTION METHODOLOGIES....................................... FIGURE 7.2-2: PART OBSOLESCENCE AND DMS PROCESS FLOW ..................... FIGURE 7.2-3: REDUCED SCREEN FLOW.................................................................. FIGURE 7.3-1: STRESS-STRENGTH DISTRIBUTIONS AND UNRELIABILITY IN DESIGN................................................................................................... FIGURE 7.3-2: NORMAL (GAUSSIAN) STRESS-STRENGTH DISTRIBUTIONS AND UNRELIABILITY IN DESIGN .................................................... FIGURE 7.3-3: FACTORS AFFECTING UNRELIABILITY......................................... FIGURE 7.4-1: ON-CHIP DIODE PROTECTION CIRCUIT......................................... FIGURE 7.4-2: (A) FOUR-LAYER STRUCTURE OF AN SCR (B) CURRENT - VOLTAGE CHARACTERISTIC ............................... FIGURE 7.4-3: GROUNDING PRACTICE AT A SINGLE PHASE SERVICE ENTRANCE .......................................................................... FIGURE 7.4-4: CIRCUIT SUBSYSTEMS WITH GROUND CONNECTIONS “DAISY-CHAINED” INVITES PROBLEMS........................................ FIGURE 7.4-5: GROUND TRACES RETURNED TO A COMMON POINT ............... FIGURE 7.4-6: DIODE PROTECTION OF A BIPOLAR TRANSISTOR ..................... FIGURE 7.4-7: DIODE PROTECTION FOR A DISCRETE MOSFET TRANSISTOR......................................................................................... FIGURE 7.4-8: DIODE PROTECTION FOR SILICON CONTROLLED RECTIFIERS ........................................................................................... FIGURE 7.4-9: TRANSIENT PROTECTION FOR A TTL CIRCUIT USING DIODES................................................................................................... FIGURE 7.4-10: TRANSIENT PROTECTION FOR A CMOS CIRCUIT ....................... FIGURE 7.4-11: INPUT PROTECTION FOR POWER SUPPLIES ................................. FIGURE 7.4-12: PROTECTION OF DATA LINES OR POWER BUSES USING A DIODE ARRAY .................................................................................. 6-4 6-5 6-6 6-8 6-23 6-27 6-45 6-56 7-6 7-14 7-25 7-35 7-36 7-37 7-41 7-44 7-52 7-53 7-54 7-58 7-58 7-59 7-59 7-60 7-60 7-61

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES Page FIGURE 7.4-13: FUSE PROTECTION FOR A TRANSIENT VOLTAGE SUPPRESSOR DIODE ........................................................................... 7-62 FIGURE 7.4-14: RESISTOR PARAMETER VARIATION WITH TIME (TYPICAL) ... 7-64 FIGURE 7.4-15: CAPACITOR PARAMETER VARIATION WITH TIME (TYPICAL).............................................................................................. 7-65 FIGURE 7.4-16: RESISTOR PARAMETER CHANGE WITH STRESS AND TIME (TYPICAL).............................................................................................. 7-66 FIGURE 7.4-17: OUTPUT VOLTAGE VERSUS TRANSISTOR GAIN BASED ON A FIGURE APPEARING IN TAGUCHI TECHNIQUES FOR QUALITY ENGINEERING (REFERENCE [21]) .................................................... 7-69 FIGURE 7.4-18: RATIO OF ICO OVER TEMPERATURE T TO ICO AT T = 25°C ... 7-79 FIGURE 7.5-1: HARDWARE REDUNDANCY TECHNIQUES ................................... 7-82 FIGURE 7.5-2: EFFECT OF MAINTENANCE CONCEPT ON LEVEL OF FAULT TOLERANCE.......................................................................................... 7-85 FIGURE 7.5-3: PARALLEL NETWORK ........................................................................ 7-88 FIGURE 7.5-4: SIMPLE PARALLEL REDUNDANCY: SUMMARY .......................... 7-91 FIGURE 7.5-5: SERIES-PARALLEL REDUNDANCY NETWORK ............................ 7-92 FIGURE 7.5-6: RELIABILITY BLOCK DIAGRAM DEPICTING REDUNDANCY AT THE SYSTEM, SUBSYSTEM, AND COMPONENT LEVELS..... 7-93 FIGURE 7.5-7: SERIES-PARALLEL CONFIGURATION ............................................ 7-94 FIGURE 7.5-8: PARALLEL-SERIES CONFIGURATION ............................................ 7-95 FIGURE 7.5-9: DECREASING GAIN IN RELIABILITY AS NUMBER OF ACTIVE ELEMENTS INCREASES...................................................................... 7-103 FIGURE 7.5-10: RELIABILITY GAIN FOR REPAIR OF SIMPLE PARALLEL ELEMENT AT FAILURE....................................................................... 7-104 FIGURE 7.5-11: PARTIAL REDUNDANT ARRAY........................................................ 7-106 FIGURE 7.5-12: RELIABILITY FUNCTIONS FOR PARTIAL REDUNDANT ARRAY OF FIGURE 7.5-11................................................................... 7-108 FIGURE 7.5-13: REDUNDANCY WITH SWITCHING................................................... 7-109 FIGURE 7.5-14: THREE-ELEMENT REDUNDANT CONFIGURATIONS WITH SWITCHING ........................................................................................... 7-111 FIGURE 7.5-15: THREE-ELEMENT VOTING REDUNDANCY ................................... 7-112 FIGURE 7.5-16: MAJORITY VOTING REDUNDANCY................................................ 7-115 FIGURE 7.5-17: SYSTEM RELIABILITY FOR N STANDBY REDUNDANT ELEMENTS............................................................................................. 7-116 FIGURE 7.5-18: LOAD SHARING REDUNDANT CONFIGURATION........................ 7-117 FIGURE 7.5-19: SUCCESS COMBINATIONS IN TWO-ELEMENT LOAD-SHARING CASE ........................................................................ 7-118 FIGURE 7.5-20: POSSIBLE REDUNDANT CONFIGURATIONS RESULTING FROM ALLOCATION STUDY ............................................................. 7-120 FIGURE 7.5-21: MARKOV MODELING PROCESS ....................................................... 7-122 xxii

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES FIGURE 7.5-22: FIGURE 7.5-23: FIGURE 7.5-24: FIGURE 7.6-1: FIGURE 7.7-1: FIGURE 7.7-2: FIGURE 7.7-3: FIGURE 7.7-4: FIGURE 7.7-5: FIGURE 7.7-6: FIGURE 7.7-7: FIGURE 7.7-8: FIGURE 7.7-9: FIGURE 7.7-10: FIGURE 7.8-1: FIGURE 7.8-2: FIGURE 7.8-3: FIGURE 7.8-4: FIGURE 7.8-5: FIGURE 7.9-1: FIGURE 7.9-2: FIGURE 7.9-3: FIGURE 7.9-4: FIGURE 7.9-5: FIGURE 7.10-1: FIGURE 7.10-2: FIGURE 7.10-3: FIGURE 7.10-4: FIGURE 7.10-5: FIGURE 7.10-6: FIGURE 7.10-7: FIGURE 7.11-1: MARKOV FLOW DIAGRAM ............................................................... TWO CHANNEL EXAMPLE ................................................................ COVERAGE EXAMPLE........................................................................ EFFECTS OF COMBINED ENVIRONMENTS.................................... THE HUMAN IN SYSTEM RELIABILITY AND MAINTAINABILITY [44]...................................................................... THE COGNITIVE HUMAN MODEL.................................................... FACTORS THAT AFFECT HUMAN FUNCTION RELIABILITY..... ZONES OF HUMAN PERFORMANCE FOR LONGITUDINAL VIBRATION (ADAPTED FROM MIL-STD-1472) .............................. HIERARCHICAL STRUCTURE OF FUNCTIONAL ANALYSIS (EXAMPLE)............................................................................................ SIMPLIFIED DYNAMIC PROGRAMMING........................................ TOOLS FOR DESIGNING HUMAN-MACHINE SYSTEMS.............. GOAL-SUCCESS TREE......................................................................... CATEGORIES OF HUMAN PERFORMANCE RELIABILITY PREDICTION METHODS ..................................................................... THERP PROBABILITY TREE [62]....................................................... TYPICAL SYSTEM SYMBOLIC LOGIC BLOCK DIAGRAM .......... TYPICAL UNIT SYMBOLIC LOGIC BLOCK DIAGRAM ................ FAILURE EFFECTS ANALYSIS FORM.............................................. SYMBOLIC LOGIC DIAGRAM OF RADAR EXAMPLE .................. DETERMINATION OF PREAMPLIFIER CRITICALITY................... FAULT TREE ANALYSIS SYMBOLS................................................. TRANSFORMATION OF TWO-ELEMENT SERIES RELIABILITY BLOCK DIAGRAM TO “FAULT TREE” LOGIC DIAGRAMS ......... TRANSFORMATION OF SERIES/PARALLEL BLOCK DIAGRAM TO EQUIVALENT FAULT TREE LOGIC DIAGRAM ....................... RELIABILITY BLOCK DIAGRAM OF HYPOTHETICAL ROCKET MOTOR FIRING CIRCUIT.................................................................... FAULT TREE FOR SIMPLIFIED ROCKET MOTOR FIRING CIRCUIT ................................................................................................. AUTOMOTIVE SNEAK CIRCUIT ....................................................... SNEAK PATH ENABLE........................................................................ REDUNDANT CIRCUIT SWITCHED GROUND................................ EXAMPLES OF CATEGORIES OF SNEAK CIRCUITS..................... BASIC TOPOGRAPHS .......................................................................... SOFTWARE TOPOGRAPHS................................................................. SOFTWARE SNEAK EXAMPLE.......................................................... DESIGN REVIEW AS A CHECK VALVE IN THE SYSTEM ENGINEERING CYCLE ........................................................................ Page 7-124 7-126 7-127 7-130 7-162 7-163 7-163 7-164 7-166 7-170 7-172 7-175 7-177 7-180 7-191 7-192 7-200 7-203 7-205 7-213 7-214 7-215 7-216 7-217 7-223 7-226 7-226 7-228 7-230 7-232 7-234 7-237

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES Page FIGURE 7.11-2: BASIC STEPS IN THE PRELIMINARY DESIGN REVIEW (PDR) CYCLE......................................................................................... FIGURE 7.11-3: DESIGN RELIABILITY TASKS FOR THE PDR................................. FIGURE 7.11-4: BASIC STEPS IN THE CDR CYCLE.................................................... FIGURE 7.11-5: DESIGN RELIABILITY TASKS FOR THE CRITICAL DESIGN REVIEW (CDR) ...................................................................................... FIGURE 7.11-6: TYPICAL AREAS TO BE COVERED IN A DESIGN REVIEW......... FIGURE 7.11-7: TYPICAL QUESTIONS CHECKLIST FOR THE DESIGN REVIEW ................................................................................................. FIGURE 7.12-1: SIMPLE SYSTEM SHOWING TEST DEPENDENCIES ..................... FIGURE 7.12-2: REDUNDANCY BIT (SOURCE: RADC-TR-89-209, VOL. II) ........... FIGURE 7.12-3: WRAP-AROUND BIT (SOURCE: RADC-TR-89-209, VOL II) .......... FIGURE 7.14-1: NODAL ANALYSIS............................................................................... FIGURE 7.14-2: DISPLACEMENT/STRESS INTERPRETATION................................. FIGURE 7.14-3: DETERMINISTIC ANALYSIS .............................................................. FIGURE 7.14-4: LIFETIME ESTIMATE .......................................................................... FIGURE 8.2-1: CLOSED LOOP FAILURE REPORTING AND CORRECTIVE ACTION SYSTEM ................................................................................. FIGURE 8.2-2: EXAMPLE OF FAILURE REPORT FORM ......................................... FIGURE 8.2-3: CLOSED LOOP FAILURE REPORTING AND CORRECTIVE ACTION SYSTEM WITH FAILURE REVIEW BOARD .................... FIGURE 8.3-1: GRAPHICAL POINT ESTIMATION FOR THE NORMAL DISTRIBUTION .................................................................................... FIGURE 8.3-2: GRAPHICAL POINT ESTIMATION FOR THE WEIBULL DISTRIBUTION .................................................................................... FIGURE 8.3-3: DISTRIBUTION GRAPHICAL EVALUATION .................................. FIGURE 8.3-4: HAZARD AND DENSITY FUNCTIONS FOR TABLE 8.3-3 ............. FIGURE 8.3-5: RELIABILITY FUNCTIONS FOR THE EXAMPLE GIVEN IN TABLE 8.3-4 .......................................................................................... FIGURE 8.3-6: NORMAL DISTRIBUTION OF FAILURE IN TIME .......................... FIGURE 8.3-7: CALCULATION AND PRESENTATION OF A NORMAL SURVIVAL CURVE .............................................................................. FIGURE 8.3-8: EXPONENTIAL DISTRIBUTION OF FAILURES IN TIME ............. FIGURE 8.3-9: CALCULATION AND PRESENTATION OF AN EXPONENTIAL CURVE ................................................................................................... FIGURE 8.3-10: OBSERVED AND THEORETICAL EXPONENTIAL SURVIVAL CURVES ................................................................................................. FIGURE 8.3-11: OBSERVED AND THEORETICAL NORMAL SURVIVAL CURVES ................................................................................................. FIGURE 8.3-12: ACTUAL RELIABILITY FUNCTION AND THEORETICAL EXPONENTIAL RELIABILITY FUNCTION ...................................... 7-242 7-243 7-244 7-245 7-246 7-249 7-258 7-261 7-261 7-276 7-277 7-277 7-278 8-4 8-8 8-9 8-14 8-20 8-21 8-25 8-28 8-30 8-30 8-30 8-30 8-32 8-32 8-34

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES Page FIGURE 8.3-13: NON-PARAMETRIC AND THEORETICAL NORMAL RELIABILITY FUNCTIONS ................................................................ 8-36 FIGURE 8.3-14: GEOMETRICAL INTERPRETATION OF THE CONCEPT OF A CONFIDENCE INTERVAL .................................................................. 8-39 FIGURE 8.3-15: TWO-SIDED CONFIDENCE INTERVAL AND LIMITS ................... 8-41 FIGURE 8.3-16: MULTIPLICATION RATIOS FOR DETERMINING UPPER AND LOWER CONFIDENCE LIMITS VS. NUMBER OF FAILURES FOR TEST TRUNCATED AT A FIXED TIME ............................................ 8-49 FIGURE 8.3-17: CHART FOR 95% CONFIDENCE LIMITS ON THE PROBABILITY S/N .......................................................................................................... 8-51 FIGURE 8.3-18: EXAMPLE OF THE APPLICATION OF THE "d" TEST .................... 8-57 FIGURE 8.3-19: FUEL SYSTEM FAILURE TIMES ....................................................... 8-62 FIGURE 8.3-20: COMPUTATION ................................................................................... 8-63 FIGURE 8.4-1: NORMAL DISTRIBUTION .................................................................. 8-69 FIGURE 8.4-2A: HYPOTHESIS TEST A .......................................................................... 8-70 FIGURE 8.4-2B: HYPOTHESIS TEST B .......................................................................... 8-70 FIGURE 8.4-3A: IDEAL OPERATING CHARACTERISTIC (OC) CURVE .................. 8-71 FIGURE 8.4-3B: TYPICAL OPERATING CHARACTERISTIC CURVE ...................... 8-71 FIGURE 8.4-4: ACTUAL OPERATING CHARACTERISTIC CURVE........................ 8-72 FIGURE 8.4-5: OC CURVE CHARACTERISTICS ....................................................... 8-73 FIGURE 8.4-6: GRAPHICAL SOLUTION OF SEQUENTIAL BINOMIAL TEST ..... 8-92 FIGURE 8.5-1: RELIABILITY GROWTH PROCESS.................................................... 8-134 FIGURE 8.5-2: RELIABILITY GROWTH PLOTS......................................................... 8-136 FIGURE 8.5-3: UP-IS-GOOD DUANE CHART WITH PLOT OF CURRENT MTBF ...................................................................................................... 8-138 FIGURE 8.5-4: FAILURE RATE VS. DEVELOPMENT TIME FOR WEIBULL FAILURE RATE .................................................................................... 8-141 FIGURE 8.5-5: FAILURE RATE VS. DEVELOPMENT TEST TIME FOR WEIBULL FAILURE RATE .................................................................................... 8-144 FIGURE 8.5-6: RELIABILITY GROWTH ANALYSIS (AMSAA MODEL) ............... 8-146 FIGURE 8.5-7: RELIABILITY GROWTH PLOTS......................................................... 8-150 FIGURE 8.5-8: COMPARISON OF CUMULATIVE LIFE CYCLE COSTS WITH AND WITHOUT SPECIFIED RELIABILITY GROWTH TEST REQUIREMENTS .................................................................................. 8-153 FIGURE 8.5-9: RELIABILITY GROWTH MANAGEMENT MODEL (ASSESSMENT) .................................................................................... 8-155 FIGURE 8.5-10: EXAMPLE OF A RELIABILITY GROWTH CURVE ......................... 8-156 FIGURE 8.5-11: INFORMATION SOURCES THAT INITIATE RELIABILITY GROWTH ............................................................................................... 8-157 FIGURE 8.6-1: RELIABILITY TESTING OPTIONS .................................................... 8-160 FIGURE 8.7-1: ARRHENIUS ACCELERATION MODEL ........................................... 8-167

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES FIGURE 8.7-2: FIGURE 8.7-3: FIGURE 9.1-1: FIGURE 9.1-2: FIGURE 9.2-1: FIGURE 9.2-2: FIGURE 9.3-1: FIGURE 9.4-1: FIGURE 9.4-2: FIGURE 9.4-3: FIGURE 9.4-4: FIGURE 9.4-5: FIGURE 9.4-6: FIGURE 9.5-1: FIGURE 9.5-2: FIGURE 9.6-1: FIGURE 9.7-1: FIGURE 9.7-2: FIGURE 9.8-1: FIGURE 10.1-1: FIGURE 10.2-1: FIGURE 10.3-1: FIGURE 10.4-1: FIGURE 10.4-2: FIGURE 10.4-3: FIGURE 10.4-4: FIGURE 10.4-5: FIGURE 10.4-6: FIGURE 10.4-7: Page STEP STRESS PROFILE ....................................................................... 8-170 PROGRESSIVE STRESS PROFILE ..................................................... 8-171 SOFTWARE ENVIRONMENT TIMELINE ......................................... 9-2 HARDWARE/SOFTWARE SYSTEM LIFE CYCLE RELATIONSHIP (REF. [2]) .................................................................. 9-4 BATHTUB CURVE FOR HARDWARE RELIABILITY .................... 9-9 REVISED BATHTUB CURVE FOR SOFTWARE RELIABILITY .... 9-11 HIGH-LEVEL SOFTWARE ARCHITECTURE EXAMPLE ............... 9-14 WATERFALL MODEL (REF. [6]) ....................................................... 9-20 THE CLASSIC DEVELOPMENT MODEL (REF. [7]) ........................ 9-21 STEPS IN THE PROTOTYPING APPROACH .................................... 9-23 SPIRAL MODEL (REF. [7]) .................................................................. 9-25 INCREMENTAL DEVELOPMENT MODEL (REF. [7]) .................... 9-27 THE CLEANROOM DEVELOPMENT PROCESS (REF. [10]) .......... 9-29 EXPECTED PROPORTION OF THE TOTAL NUMBER OF DEFECTS ............................................................................................... 9-35 EXPONENTIAL MODEL BASIS ......................................................... 9-41 RELIABILITY ALLOCATION PROCESS (REF. [2]) ......................... 9-52 STRUCTURAL REPRESENTATION OF A SOFTWARE SYSTEM ................................................................................................. 9-60 FLOWCHART FOR SOFTWARE FAILURE DATA ANALYSIS AND DECISION-MAKING .................................................................. 9-63 EXAMPLE OF SOFTWARE FMECA .................................................. 9-68 THE COMMERCIAL/NDI DECISION PROCESS .............................. 10-7 SYSTEM EFFECTIVENESS MODELS ............................................... 10-15 PART DATABASE DISTRIBUTION ................................................... 10-22 PRINCIPAL STEPS REQUIRED FOR EVALUATION OF SYSTEM EFFECTIVENESS .................................................................................. 10-32 THE AVAILABILITY OF A SINGLE UNIT ....................................... 10-35 AVERAGE AND POINTWISE AVAILABILITY ................................ 10-39 BLOCK DIAGRAM OF A SERIES SYSTEM ...................................... 10-42 HYPOTHETICAL HISTORY OF MACHINE GUN USAGE .............. 10-56 RENEWAL PROCESS IN TERMS OF ROUNDS FIRED ................... 10-57 OPERATIONAL READINESS PROBABILITY VERSUS QUEUING FACTOR ". FOR POPULATION SIZE N = 15; NUMBER OF REPAIR CHANNELS k ........................................................................................ 10-72 OPERATIONAL READINESS PROBABILITY VERSUS QUEUING FACTOR ". FOR POPULATION SIZE N = 20; NUMBER OF REPAIR CHANNELS k ........................................................................................ 10-73 RELIABILITY - MAINTAINABILITY - AVAILABILITY RELATIONSHIPS .................................................................................. 10-77

FIGURE 10.4-8:

FIGURE 10.6-1:

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES Page AVAILABILITY AS A FUNCTION OF #/? ........................................ 10-78 AVAILABILITY AS A FUNCTION OF MTBF AND 1/MTTR .......... 10-78 AVAILABILITY NOMOGRAPH ......................................................... 10-79 RELIABILITY-MAINTAINABILITY TRADE-OFFS ......................... 10-82 BLOCK DIAGRAM OF A SERIES SYSTEM ...................................... 10-84 PERMISSIBLE EQUIPMENT FAILURE AND REPAIR RATES FOR=#/? = .25 ......................................................................................... 10-97 FIGURE 10.7-2: UNAVAILABILITY CURVES ............................................................. 10-98 FIGURE 10.10-1: LCC CATEGORIES VS. LIFE CYCLE ............................................... 10-111 FIGURE 10.10-2: R&M AND COST METHODS ............................................................. 10-114 FIGURE 10.10-3: LIFE CYCLE COSTS VS. RELIABILITY ........................................... 10-116 FIGURE 11.1-1: RELIABILITY LIFE CYCLE DEGRADATION & GROWTH CONTROL .............................................................................................. 11-2 FIGURE 11.2-1: QUALITY ENGINEERING AND CONTROL OVER TIME ............... 11-5 FIGURE 11.2-2: ISO 9000 FAMILY OF STANDARDS .................................................. 11-7 FIGURE 11.2-3: LIFE CHARACTERISTIC CURVE ...................................................... 11-16 FIGURE 11.2-4: IMPACT OF DESIGN AND PRODUCTION ACTIVITIES ON EQUIPMENT RELIABILITY ............................................................... 11-18 FIGURE 11.2-5: “STEP” MTBF APPROXIMATION ...................................................... 11-19 FIGURE 11.2-6: MTBF (OUTGOING FROM PRODUCTION) ESTIMATING PROCESS ............................................................................................... 11-23 FIGURE 11.2-7: SAMPLE PROCESS FLOW DIAGRAM .............................................. 11-24 FIGURE 11.2-8: A TYPICAL PRODUCTION PROCESS, FINDING DEFECTS AT THE LOWEST LEVEL OF MANUFACTURE IS THE MOST COSTEFFECTIVE ........................................................................................... 11-28 FIGURE 11.2-9: APPLICATION OF SCREENING WITHIN THE MANUFACTURING PROCESS ........................................................... 11-29 FIGURE 11.2-10: EFFECTIVENESS OF ENVIRONMENTAL SCREENS ..................... 11-31 FIGURE 11.2-11: MIL-HDBK-344 ESS PROCESS .......................................................... 11-35 FIGURE 11.2-12: SAMPLE ENVIRONMENTAL TEST CYCLE ................................... 11-49 FIGURE 11.2-13: REJECT-ACCEPT CRITERIA FOR TEST PLAN XVIIIC ................. 11-50 FIGURE 11.4-1: PROTECTIVE CONTROL DURING SHIPMENT AND STORAGE . 11-60 FIGURE 11.4-2: TECHNICAL APPROACH TO STORAGE SERVICEABILITY STANDARDS (SSS) ............................................................................... 11-64 FIGURE 11.4-3: STORAGE SERVICEABILITY STANDARD PREPARATION PROCESS ................................................................................................ 11-68 FIGURE 11.4-4: DETERIORATION CLASSIFICATION OF MATERIAL ................... 11-69 FIGURE 11.4-5: INSPECTION FREQUENCY MATRIX ................................................ 11-71 FIGURE 11.4-6: CODED QUALITY INSPECTION LEVELS ........................................ 11-73 FIGURE 12.3-1: CHECKLIST FOR EVALUATING RELIABILITY PORTION OF A PROPOSAL ............................................................................................ 12-16 xxvii

FIGURE 10.6-2: FIGURE 10.6-3: FIGURE 10.6-4: FIGURE 10.6-5: FIGURE 10.6-6: FIGURE 10.7-1:

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF FIGURES FIGURE 12.5-1: LIFE CYCLE PHASES OF A PRODUCT ............................................ FIGURE 12.8-1: CONCURRENT SYSTEM DEVELOPMENT PROCESS FOR BOTH HARDWARE AND SOFTWARE (REF. [6]) ....................................... FIGURE 12.8-2: SOFTWARE RELIABILITY PROGRAM ELEMENTS BY PROGRAM PHASE ............................................................................... FIGURE 12.8-3: BALANCED DESIGN APPROACH ..................................................... FIGURE 12.8-4: EXPENDITURES DURING LIFE CYCLE ........................................... FIGURE 12.8-5: EFFECT OF EARLY DECISION ON LIFE CYCLE COST ................ FIGURE 12.8-6: LIFE CYCLE COST ACTIVITIES ........................................................ Page 12-21 12-33 12-36 12-41 12-42 12-42 12-46

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF TABLES TABLE 4.5-1: TABLE 5.3-1: TABLE 5.3-2: TABLE 5.3-3: TABLE 5.6-1: TABLE 5.6-2: TABLE 5.6-3: TABLE 5.6-4: TABLE 5.6-5: PARTIAL LIST OF OPTIMIZATION TECHNIQUES ........................ VALUES OF THE STANDARD NORMAL DISTRIBUTION FUNCTION ............................................................................................ ORDINATES F(z) OF THE STANDARD NORMAL CURVE AT z .. GAMMA FUNCTION $(n) .................................................................. COMPARISON OF BASIC RELIABILITY AND MAINTAINABILITY FUNCTIONS ..................................................... VALUES OF % OR Z(T’(1-&)) MOST COMMONLY USED IN MAINTAINABILITY ANALYSIS ....................................................... TIME-TO-REPAIR DATA ON A GROUND ELECTRONIC SYSTEM ................................................................................................. CALCULATIONS TO DETERMINE t' AND !'=FOR THE DATA IN TABLE 5.6-3 .................................................................................... THE PROBABILITY DENSITY OF TIME-TO-REPAIR DATA (FROM TABLE 5.6.2.1.1-1 BASED ON THE STRAIGHT TIMES TO REPAIR AND THE NATURAL LOGARITHM OF THE TIMES TO REPAIR USED TO PLOT FIGURES 5.6-3 AND 5.6-4, RESPECTIVELY.*) ............................................................................... VALUES OF % FOR SPECIFIED & ...................................................... VALUES OF kE FOR SPECIFIED & ..................................................... THE AVAILABILITY OF A SINGLE SYSTEM OR UNIT ................ MECHANICAL-ELECTRICAL SYSTEM ........................................... USES OF RELIABILITY MODELS AND PREDICTIONS ................. TRUTH TABLE CALCULATION FOR THE SYSTEM RELIABILITY DIAGRAM ................................................................... REDUCTION TABULATION ............................................................... LOGIC DIAGRAM EXAMPLES .......................................................... PROS AND CONS OF PHYSICS-OF-FAILURE PREDICTION MODELS ................................................................................................ ENVIRONMENTAL SYMBOL IDENTIFICATION AND DESCRIPTION ...................................................................................... RELIABILITY ANALYSIS SIMILAR ITEM ....................................... GENERIC FAILURE RATE - #G (FAILURES PER 106 HOURS) FOR DISCRETE SEMICONDUCTORS................................................ DISCRETE SEMICONDUCTOR QUALITY FACTORS - (Q ............. MAJOR INFLUENCE FACTORS ON PART RELIABILITY ............. FORMULAS FOR CALCULATING MICROCIRCUIT RELIABILITY ........................................................................................ BIPOLAR COMPLEXITY FAILURE RATE C1 .................................. ENVIRONMENTAL FACTOR - (E ...................................................... Page 4-13 5-12 5-13 5-20 5-46 5-51 5-52 5-54

TABLE 5.6-6: TABLE 5.6-7: TABLE 5.7-1: TABLE 6.3-1: TABLE 6.4-1: TABLE 6.4-2: TABLE 6.4-3: TABLE 6.4-4: TABLE 6.4-5: TABLE 6.4-6: TABLE 6.4-7: TABLE 6.4-8: TABLE 6.4-9: TABLE 6.4-10: TABLE 6.4-11: TABLE 6.4-12: TABLE 6.4-13:

5-57 5-65 5-68 5-82 6-16 6-21 6-35 6-37 6-39 6-46 6-47 6-52 6-55 6-56 6-57 6-58 6-60 6-61

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF TABLES Page 6-61 6-69 6-70 7-7 7-11 7-17 7-31 7-32 7-48 7-56 7-57 7-68 7-83 7-100 7-107 7-129 7-131 7-135 7-142 7-150 7-154 7-156 7-158 7-160 7-167 7-171 7-172 7-185 7-193 7-200 7-207 7-207 7-209 7-241 7-247

TABLE 6.4-14: TABLE 6.4-15: TABLE 6.4-16: TABLE 7.2-1: TABLE 7.2-2: TABLE 7.2-3: TABLE 7.3-1: TABLE 7.3-2: TABLE 7.4-1: TABLE 7.4-2: TABLE 7.4-3: TABLE 7.4-4: TABLE 7.5-1: TABLE 7.5-2: TABLE 7.5-3: TABLE 7.6-1: TABLE 7.6-2: TABLE 7.6-3: TABLE 7.6-4: TABLE 7.6-5: TABLE 7.6-6: TABLE 7.6-7: TABLE 7.6-8: TABLE 7.7-1: TABLE 7.7-2: TABLE 7.7-3: TABLE 7.7-4: TABLE 7.7-5: TABLE 7.8-1: TABLE 7.8-2: TABLE 7.8-3: TABLE 7.8-4: TABLE 7.8-5: TABLE 7.11-1: TABLE 7.11-2: xxx

QUALITY FACTORS - (Q .................................................................... BASIC APPROACH TO RELIABILITY PHYSICS ANALYSIS ........ EXAMPLE OF A PINION RELIABILITY ANALYSIS ...................... QUESTIONS FOR PART SUPPLIERS.................................................. HIDDEN HYBRID CHECKLIST........................................................... GENERIC PART APPLICATION FACTORS....................................... PRINCIPLE RELIABILITY DEPENDENT STRESS FACTORS/DERATING FACTORS....................................................... DERATING VALUES FOR TRANSISTORS........................................ COMPARISON OF PROTECTION DEVICES ..................................... 0.5?S - 100 KHZ RING WAVE.............................................................. 8/20?S, 1.2/50?S COMBINATION WAVE........................................... COMPARISON OF VARIABILITY ANALYSIS METHODS ............. DIAGNOSTIC IMPLICATIONS OF FAULT TOLERANT DESIGN APPROACHES ....................................................................................... REDUNDANCY TECHNIQUES ........................................................... RELIABILITY CALCULATIONS FOR EXAMPLE 2 ......................... ENVIRONMENTAL COVERAGE CHECKLIST (TYPICAL) ............ VARIOUS ENVIRONMENTAL PAIRS................................................ ENVIRONMENTAL EFFECTS ............................................................. LOW TEMPERATURE PROTECTION METHODS ............................ ENVIRONMENTAL STRESSES IMPROVEMENT TECHNIQUES IN ELECTRONIC EQUIPMENT ........................................................... SYSTEM USE CONDITIONS CHECKLIST (TYPICAL) .................... ENVIRONMENTAL ANALYSIS (INDUCED ENVIRONMENT) ...... ASSOCIATION OF FACTOR IMPORTANCE WITH REGION OF ENVIRONMENT ................................................................................... COMPARISON BETWEEN HARDWARE AND HUMAN RELIABILITY [39]................................................................................. HUMAN-MACHINE COMPARATIVE CAPABILITIES..................... DATA BANKS AND THEIR AFFILIATIONS [55] ............................. DATA CATEGORIES OF NATIONAL DATA BANKS [55] .............. MAPPS SCOPE....................................................................................... FAILURE MODE DISTRIBUTION OF PARTS ................................... COLUMN DESCRIPTIONS FOR FIGURE 7.8-3 ................................. SEVERITY CLASSIFICATION............................................................. OCCURRENCE RANKING ................................................................... DETECTION RANKING........................................................................ DESIGN REVIEW GROUP, RESPONSIBILITIES AND MEMBERSHIP SCHEDULE.................................................................. RELIABILITY ACTIONS CHECKLIST ...............................................

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF TABLES Page TABLE 7.12-1: TABLE 7.12-2: TABLE 7.12-3: TABLE 7.13-1: TABLE 7.13-2: TABLE 8.3-1: TABLE 8.3-2: TABLE 8.3-3: TABLE 8.3-4: TABLE 8.3-5: TABLE 8.3-6: TABLE 8.3-7: TABLE 8.3-8: TABLE 8.3-9: TABLE 8.3-10: TABLE 8.3-11: TABLE 8.3-12: RISKS AND CONSEQUENCES OF NOT MAKING BIT PART OF PRODUCT DESIGN ............................................................................... FIRST ORDER DEPENDENCY MODEL FOR SIMPLE SYSTEM .... INHERENT TESTABILITY CHECKLIST............................................ APPLICATION MATRIX FOR SYSTEM PROGRAM DEVELOPMENT.................................................................................... APPLICATION MATRIX FOR FACILITIES ACQUISITION............. DATA ON TIMES TO FAILURE OF 20 ITEMS ................................. MEDIAN RANKS .................................................................................. FAILURE DATA FOR TEN HYPOTHETICAL ELECTRONIC COMPONENTS ..................................................................................... COMPUTATION OF DATA FAILURE DENSITY AND DATA HAZARD RATE .................................................................................... FAILURE DATA FOR 1,000 B-52 AIRCRAFT ................................... TIME-TO-FAILURE DATA FOR S = 1000 MISSION HOURS ......... COMPUTATION OF THEORETICAL EXPONENTIAL RELIABILITY FUNCTION FOR MTBF = 1546 HOURS ................... OBSERVED FAILURE DATA ............................................................. CONFIDENCE LIMITS - NORMAL DISTRIBUTION ....................... CONFIDENCE INTERVAL .................................................................. DISTRIBUTION OF )2 (CHI-SQUARE)............................................... FACTORS FOR CALCULATION OF MEAN LIFE CONFIDENCE INTERVALS FROM TEST DATA (FACTORS = 2/)2P,D) ............................................................................. CRITICAL VALUES d&;n OF THE MAXIMUM ABSOLUTE DIFFERENCE BETWEEN SAMPLE AND POPULATION RELIABILITY FUNCTIONS ................................................................ ACTIVATION ENERGIES ASSOCIATED WITH VARIOUS SILICON SEMICONDUCTOR FAILURE MECHANISMS ................ ASSESSING THE ORGANIZATIONAL COMMUNICATIONS GAP ........................................................................................................ SUMMARY: LIFE CYCLE DIFFERENCES ....................................... SOFTWARE DESIGN TECHNIQUES ................................................. SOFTWARE CODING TECHNIQUES ................................................ SOFTWARE DEVELOPMENT PROCESS SELECTION ................... CLEANROOM PERFORMANCE MEASURES (REF. [11]) .............. COMPARING PREDICTION AND ESTIMATION MODELS ........... SOFTWARE RELIABILITY PREDICTION TECHNIQUES .............. TERMS IN MUSA’S EXECUTION TIME MODEL ............................ PUTNAM’S TIME AXIS MILESTONES ............................................. RL-TR-92-52 TERMINOLOGY ............................................................ 7-257 7-258 7-263 7-273 7-274 8-12 8-15 8-23 8-24 8-26 8-27 8-34 8-35 8-40 8-42 8-44

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF TABLES Page AMOUNT OF HISTORICAL DATA INCLUDED .............................. 9-36 SUMMARY OF THE RL-TR-92-52 MODEL ...................................... 9-37 REGRESSION EQUATION COEFFICIENTS ..................................... 9-39 NOTATIONS FOR THE EXPONENTIAL DISTRIBUTION MODEL .................................................................................................. 9-41 TABLE 9.5-10: VARIOUS EXPONENTIAL MODELS ................................................ 9-42 TABLE 9.6-1: SOFTWARE RELIABILITY ALLOCATION TECHNIQUES (REF. [2]) ................................................................................................ 9-52 TABLE 9.6-2: SOFTWARE FUNCTIONS BY SYSTEM MODE - EXAMPLE ......... 9-51 TABLE 9.6-3: COMPLEXITY PROCEDURES ............................................................ 9-56 TABLE 9.8-1: HARDWARE FAILURE SEVERITY LEVELS (REF. [26]) ................ 9-65 TABLE 9.8-2: SOFTWARE FAILURE SEVERITY LEVELS (REF. [5]) ................... 9-66 TABLE 9.8-3: SOFTWARE FAILURE MODES AND CRITICALITY ANALYSIS CATEGORIES ........................................................................................ 9-67 TABLE 10.1-1: CONCEPT OF SYSTEM EFFECTIVENESS ....................................... 10-1 TABLE 10.1-2: ADVANTAGES AND DISADVANTAGES OF COTS/NDI ............... 10-5 TABLE 10.1-3: R&M ACTIVITIES FOR NEW DEVELOPMENT ITEMS AND FOR COTS ............................................................................................. 10-6 TABLE 10.3-1: SYSTEM R&M PARAMETERS ........................................................... 10-20 TABLE 10.3-2: PART QUALITY FACTORS (MULTIPLY SERIES MTBF BY) ........ 10-22 TABLE 10.3-3: ENVIRONMENTAL CONVERSION FACTORS (MULTIPLY SERIES MTBF BY) ......................................................... 10-23 TABLE 10.3-4: TEMPERATURE CONVERSION FACTORS (MULTIPLY SERIES MTBF BY) ......................................................... 10-24 TABLE 10.3-5: AIRCRAFT RECEIVER CONVERSION: AIRBORNE OPERATING TO GROUND DORMANT FAILURE RATE (EXAMPLE) ........................................................................................... 10-25 TABLE 10.3-6: RELIABILITY TRANSLATION MODELS ......................................... 10-26 TABLE 10.3-7: DEFINITIONS OF KEY R&M SYSTEM PARAMETERS .................. 10-29 TABLE 10.4-1: AVAILABILITY OF SOME REDUNDANT SYSTEMS BASED ON EXPONENTIAL FAILURE AND REPAIR DISTRIBUTIONS .... 10-48 TABLE 10.6-1: ALTERNATIVE DESIGN TRADE-OFF CONFIGURATIONS .......... 10-83 TABLE 10.6-2: COST COMPARISON OF ALTERNATIVE DESIGN CONFIGURATIONS .............................................................. 10-83 TABLE 10.7-1: PRELIMINARY SYSTEM AND SUBSYSTEM RELIABILITY SPECIFICATIONS ................................................................................. 10-95 TABLE 10.10-1: LIFE CYCLE COST BREAKDOWN ..................................................... 10-115 TABLE 11.2-1: MIL-Q-9858 QUALITY PROGRAM ELEMENTS .............................. 11-9 TABLE 11.2-2: QUALITY ENGINEERING TASKS ..................................................... 11-12 TABLE 11.2-3: FOUR TYPES OF FAILURES .............................................................. 11-15 TABLE 9.5-6: TABLE 9.5-7: TABLE 9.5-8: TABLE 9.5-9:

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MIL-HDBK-338B TABLE OF CONTENTS LIST OF TABLES Page TABLE 11.2-4: TABLE 11.2-5: TABLE 11.2-6: TABLE 11.2-7: TABLE 11.2-8: TABLE 11.4-1: TABLE 11.4-2: TABLE 11.5-1: TABLE 12.4-1: TABLE 12.5-1: TABLE 12.5-2. TABLE 12.5-3: TABLE 12.5-4: TABLE 12.8-1: TABLE 12.8-2: SCREENING ENVIRONMENTS VERSUS TYPICAL FAILURE MECHANICS ......................................................................................... RISKS AND RESULTS OF ESS AT VARIOUS LEVELS .................. BASELINE VIBRATION PROFILE ..................................................... BASELINE THERMAL CYCLE PROFILE ......................................... TEST CONDITIONS MATRIX (TAKEN FROM MIL-HDBK-781) ... FAILURE MODES ENCOUNTERED WITH ELECTRONIC COMPONENTS DURING STORAGE ................................................. STORAGE-INDUCED QUALITY DEFECTS ...................................... DEPOT MAINTENANCE REQUIREMENT AREAS ......................... COMMON RELIABILITY PROGRAM ELEMENTS ......................... RELIABILITY PROGRAM ACTIVITIES TO BE CONSIDERED IN THE CONCEPT EXPLORATION PHASE....................................... RELIABILITY PROGRAM ACTIVITIES TO BE CONSIDERED IN THE PROGRAM DEFINITION AND RISK REDUCTION PHASE .................................................................................................... RELIABILITY PROGRAM ACTIVITIES TO BE CONSIDERED IN THE ENGINEERING AND MANUFACTURING DEVELOPMENT PHASE ..................................................................... RELIABILITY PROGRAM ACTIVITIES TO BE CONSIDERED IN THE PRODUCTION, DEPLOYMENT, AND OPERATIONAL SUPPORT PHASE ................................................................................. TYPES OF DESIGN-TO-COST PROGRAMS ..................................... FEATURES OF CURRENT WARRANTY-GUARANTEE PLANS ... 11-37 11-39 11-42 11-43 11-48 11-59 11-65 11-79 12-18 12-22 12-23 12-24 12-25 12-44 12-52

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MIL-HDBK-338B SECTION 1: INTRODUCTION 1.0 1.1 SCOPE Introduction

This Handbook provides procuring activities and development contractors with an understanding of the concepts, principles, and methodologies covering all aspects of electronic systems reliability engineering and cost analysis as they relate to the design, acquisition, and deployment of DoD equipment/systems. 1.2 Application

This Handbook is intended for use by both contractor and government personnel during the conceptual, validation, full scale development, production phases of an equipment/system life cycle. 1.3 Organization

The Handbook is organized as follows: SECTION 2 SECTION 3 SECTION 4 SECTION 5 SECTION 6 SECTION 7 SECTION 8 SECTION 9 SECTION 10 SECTION 11 SECTION 12 Referenced Documents Definitions General Statements Reliability/Maintainability/Availability Theory Reliability Specification, Allocation and Prediction Reliability Engineering Design Guidelines Reliability Data Collection and Analysis, Demonstration and Growth Software Reliability Systems Reliability Engineering Production and Use (Deployment) R&M R&M Management Considerations

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SECTION 2: REFERENCED DOCUMENTS 2 .0 REFERENCED DOCUMENTS

The documents cited in this section are for guidance and information. 2.1 Government Documents 2.1.1 Specifications, Standards and Handbooks

The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and applicable supplement thereto. SPECIFICATIONS Military MIL-E-4158 MIL-E-5400 MIL-E-16400 MIL-E-17555 MIL-M-28787 MIL-H-38534 MIL-I-38535 MIL-H-46855 MIL-PRF-19500K MIL-PRF-3853C MIL-S-52779 General Specification For Ground Electronic Equipment General Specifications For Aerospace Electronic Equipment General Specification For Naval Ship and Shore: Electronic, Interior Communication and Navigation Equipment Packaging of Electronic and Electrical Equipment, Accessories, and Provisioned Items (Repair Parts) General Specification For Standard Electronic Modules General Specification For Hybrid Microcircuits General Specification For Manufacturing Integrated Circuits Human Engineering Requirements For Military Systems, Equipment and Facilities General Specification For Semiconductor Devices General Specification For Microcircuits Software Quality Assurance Program Requirements

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SECTION 2: REFERENCED DOCUMENTS STANDARDS Military MIL-STD-210 MIL-STD-414 MIL-STD-701 MIL-STD-721 MIL-STD-750 MIL-STD-756 MIL-STD-790 MIL-STD-810 MIL-STD-882 MIL-STD-883 MIL-STD-975 MIL-STD-1472 MIL-STD-1562 MIL-STD-1670 MIL-STD-1686 Climatic Extremes For Military Equipment Sampling Procedures and Tables For Inspection by Variables For Percent Lists of Standard Semiconductor Devices Definitions of Terms For Reliability, and Maintainability Tests Methods For Semiconductor Devices Reliability Modeling and Prediction Reliability Assurance Program For Electronic Part Specifications Environmental Test Methods and Engineering Guidelines System Safety Program Requirements Test Methods and Procedures For Microelectronics Standard Parts Derating Guidelines Human Engineering Design Criteria For Military Systems, Equipment and Facilities Lists of Standard Microcircuits Environmental Criteria and Guidelines for Air Launched Weapons Electrostatic Discharge Control Program For Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) Certification Requirements For Hybrid Microcircuit Facility and Lines Failure Reporting, Analysis and Corrective Action System Defense System Software Development

MIL-STD-1772 MIL-STD-2155 MIL-STD-2167

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SECTION 2: REFERENCED DOCUMENTS HANDBOOKS Military MIL-HDBK-454 MIL-HDBK-470 MIL-HDBK-471 MIL-HDBK-781 MIL-HDBK-965 MIL-HDBK-1547 MIL-HDBK-2084 MIL-HDBK-2164 MIL-HDBK-2165 Standard General Requirements For Electronic Equipment Maintainability Program Requirements For Systems and Equipment Maintainability Verification/Demonstration/Evaluation Reliability Testing For Engineering Development, Qualification and Production Parts Control Program Technical Requirements For Parts, Materials, and Processes for Space and Launch Vehicles General Requirements For Maintainability Environmental Stress Screening Process For Electronic Equipment Testability Program For Electronic Systems and Equipment

Unless otherwise indicated, copies of federal and military specification, standards, handbooks and bulletins are available from: Standardization Documents Order Desk Bldg. 4D 700 Robbins Avenue Philadelphia, PA 19110-5094 For Assistance: (215) 697-2667 or 2179 Telephone Order Entry System (Touch-Tone Access Only): (215) 697-1187 FAX: (215) 697-2978 Copies of the DODISS's are also available on a yearly subscription basis from the Standardization Documents Order Desk. 2.2 Other Referenced Documents

Other referenced documents, government and non-government are listed in other sections of this handbook under “REFERENCES.”

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS 3.0 3.1 DEFINITIONS OF TERMS AND ACRONYMS AND ABBREVIATIONS Introduction

The information contained herein is intended for reference only. Many definitions, acronyms, and abbreviations are used in the field of reliability, and no attempt has been made to list them all here. Instead, a compilation of terms from historical documents (such as MIL-STD-721) and key terms from this handbook is provided. In addition, a list of acronyms and abbreviations used in this handbook or commonly associated with reliability and related disciplines, together with their meanings, is provided for the convenience of the reader. For additional terms and definitions, the reader is referred to the Product Assurance Dictionary by Richard R. Landers, 1996 and those references listed in RL-TR-97-27, “A Primer of US and Non-US Commercial and Government Documents,” March 1997. 3.2 Definitions

-AACCESSIBILITY: A measure of the relative ease of admission to the various areas of an item for the purpose of operation or maintenance. ACCEPTANCE TEST: A test conducted under specified conditions by or on behalf of the customer, using delivered or deliverable items, to determine whether or not the item satisfies specified requirements. Includes acceptance of first production units. ACHIEVED: Obtained as verified by measurement, as in "achieved reliability performance." ACTIVE TIME: That time during which an item is in an operational inventory. ADMINISTRATIVE TIME: That element of delay time, not included in the supply delay time. AFFORDABILITY: Affordability is a measure of how well customers can afford to purchase, operate, and maintain a product over its planned service life. Affordability is a function of product value and product costs. It is the result of a balanced design in which long-term support costs are considered equally with near-term development and manufacturing costs. ALERT TIME: That time during which a product is immediately ready to perform its function or mission if required. No maintenance or other activities that would impede or slow the start of the function or mission is permitted. ALIGNMENT: Performing the adjustments necessary to return an item to specified operation.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS AMBIGUITY: The inability to distinguish which of two or more subunits of a product or item has failed. AMBIGUITY GROUP: The number of possible subunits of a product or item identified by BIT, ETE, or manual test procedures, which might contain the failed hardware or software component. ANTHROPOMETRICS: Quantitative descriptions and measurements of the physical body variations in people. These are useful in human factors design. AUTOMATIC TEST EQUIPMENT (ATE): Equipment that is designed to automatically conduct analysis of functional or static parameters and to evaluate the degree of UUT (Unit Under Test) performance degradation; and may be used to perform fault isolation of UUT malfunctions. The decision making, control, or evaluative functions are conducted with minimum reliance on human intervention and usually done under computer control. AVAILABILITY: A measure of the degree to which an item is in an operable and committable state at the start of a mission when the mission is called for at an unknown (random) time. (Item state at start of a mission includes the combined effects of the readiness-related system R & M parameters, but excludes mission time.)

-BBUILT-IN-TEST (BIT): An integral capability of the mission equipment which provides an onboard, automated test capability, consisting of software or hardware (or both) components, to detect, diagnose, or isolate product (system) failures. The fault detection and, possibly, isolation capability is used for periodic or continuous monitoring of a system's operational health, and for observation and, possibly, diagnosis as a prelude to maintenance action. BUILT-IN TEST EQUIPMENT (BITE): Any device permanently mounted in the prime product or item and used for the express purpose of testing the product or item, either independently or in association with external test equipment. BURN-IN: Also known as preconditioning, burn-in is the operation of an item under stress to stabilize its characteristics. Not to be confused with debugging.

-CCALIBRATION: A comparison of a measuring device with a known standard and a subsequent adjustment to eliminate any differences. Not to be confused with alignment. CHARGEABLE: Within the responsibility of a given organizational entity. Used with terms such as failures, maintenance time, etc.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS CHECKOUT TIME: That element of maintenance time during which performance of an item is verified to be a specified condition. CHECKOUT: Tests or observations of an item to determine its condition or status. COMMERCIAL ITEM: Any item, other than real property, that is of a type customarily used for nongovernmental purposes and that has been sold, leased, or licensed to the general public, or has been offered for sale, lease, or license to the general public; items evolved from these items that are not yet available in the commercial market but will be in time to meet the delivery requirements of a solicitation. (See “Buying Commercial and Non-Developmental Items: A Handbook [SD-2, Apr 1996, OUSD/A&T]” or the Federal Acquisition Regulation, Parts 6, 10, 11, 12 and 14, for a complete definition and criteria.) COMMERCIAL-OFF-THE-SHELF (COTS): Items available in a domestic or foreign commercial marketplace and usually ordered by part number. COMPONENT: Within a product, system, subsystem, or equipment, a component is a constituent module, part, or item. COMPUTER-AIDED DESIGN (CAD): A process which uses a computer system to assist in the creation, modification, verification, and display of a design. CONFIGURATION ITEM (CI): A collection of hardware and software which satisfies a defined end-use function. The CI is designated for separate as-designed, as-built and as-shipped content makeup management control. CONTRACT DELIVERABLES REQUIREMENTS LIST (CDRL): A listing of all technical data and information which the contractor must deliver to the Customer. CORRECTIVE ACTION: A documented design, process, procedure, or materials change implemented and validated to correct the cause of failure or design deficiency. CORRECTIVE MAINTENANCE (CM): All actions performed as a result of failure, to restore an item to a specified condition. Corrective maintenance can include any or all of the following steps: Localization, Isolation, Disassembly, Interchange, Reassembly, Alignment and Checkout. CRITICAL DESIGN REVIEW (CDR): The comparative evaluation of an item and program parameters. It is usually held just prior to production release after the item has reached a degree of completion permitting a comprehensive examination and analysis. CRITICALITY: A relative measure of the consequence and frequency of occurrence of a failure mode.

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-DDATA ITEM DESCRIPTION (DID): A Government form used to define and describe the written outputs required from a contractor. DEBUGGING: A process to detect and remedy inadequacies in an item. Not to be confused with burn-in, fault-isolation, or screening. DEGRADATION: A gradual decrease in an item's characteristic or ability to perform. DELAY TIME: That element of downtime during which no maintenance is being accomplished on the item because of either supply or administrative delay. DEMONSTRATED: That which has been measured using objective evidence gathered under specified and predetermined conditions. DEMONSTRATION TEST: A test conducted under specified conditions, by or on behalf of the customer, using items representative of the production configuration, in order to determine compliance with item design requirements as a basis for production approval (also known as a Qualification Test). DEPENDABILITY: A measure of the degree to which an item is operable and capable of performing its required function at any (random) time during a specified mission profile, given that the item is available at mission start. (Item state during a mission includes the combined effects of the mission-related system R&M parameters but excludes non-mission time; see availability.) DERATING: (a) Using an item in such a way that applied stresses are below rated values. (b) The lowering of the rating of an item in one stress field to allow an increase in another stress field. DETECTABLE FAILURE: Failures at the component, equipment, subsystem, or system (product) level that can be identified through periodic testing or revealed by an alarm or an indication of an anomaly. DEVELOPMENT TEST: Testing performed during development and integration to ensure critical design parameters are met, verify the performance of an item's design, and produce data supporting design improvements. Development test, sometimes called engineering test, also discloses deficiencies and verifies that corrective action effectively prevents recurrence of these deficiencies. Properly done, development test reduces the risk of redesign being necessary following demonstration testing or delivery to the customer.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS DEVELOPMENT TEST AND EVALUATION (DT&E): Test and evaluation focused on the technological and engineering aspects of the product (system, subsystem, or equipment). DIAGNOSTICS: The hardware, software, or other documented means used to determine that a malfunction has occurred and to isolate the cause of the malfunction. Also refers to "the action of detecting and isolating failures or faults." DIRECT MAINTENANCE MANHOURS PER MAINTENANCE ACTION (DMMH/MA): A measure of the maintainability parameter related to item demand for maintenance labor. The sum of direct maintenance labor hours divided by the total number of preventive and corrective maintenance actions during a stated period of time. DIRECT MAINTENANCE MANHOURS PER MAINTENANCE EVENT (DMMH/ME): A measure of the maintainability parameter related to item demand for maintenance labor. The sum of direct maintenance labor hours, divided by the total number of preventive and corrective maintenance events during a stated period of time. DISASSEMBLE: Opening an item and removing a number of parts or subassemblies to make the item that is to be replaced accessible for removal. This does not include the actual removal of the item to be replaced. DORMANT: A state in which an item is able to but is not required to function. Most often associated with long-term storage and "wooden" rounds. Not to be confused with downtime. DOWNING EVENT: An event which causes an item to become unavailable to begin a mission (i.e., the transition from up-time to down-time). DOWNTIME: That element of time during which an item is in an operational inventory but is not in condition to perform its required function. DURABILITY: A measure of an item's useful life (a special case of reliability). Often referred to as ruggedness.

-EENVIRONMENT: The aggregate of all external and internal conditions (such as temperature, humidity, radiation, magnetic and electrical fields, shock, vibration, etc.), whether natural, manmade, or self-induced, that influences the form, fit, or function of an item. ENVIRONMENTAL STRESS SCREENING (ESS): A series of tests conducted under environmental stresses to disclose weak parts and workmanship defects so that corrective action can be taken.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS EQUIPMENT: A general term designating an item or group of items capable of performing a complete function.

-FFAILURE: The event, or inoperable state, in which any item or part of an item does not, or would not, perform as previously specified. FAILURE ANALYSIS: Subsequent to a failure, the logical systematic examination of an item, its construction, application, and documentation to identify the failure mode and determine the failure mechanism and its basic course. FAILURE, CATASTROPHIC: A failure that causes loss of the item, human life, or serious collateral damage to property. FAILURE, CRITICAL: A failure or combination of failures that prevents an item from performing a specified mission. FAILURE, DEPENDENT: A failure of one item caused by the failure of an associated item(s). A failure that is not independent. FAILURE EFFECT: The consequence(s) a failure mode has on the operation, function, or status of an item. Failure effects are typically classified as local, next higher level, and end. FAILURE, INDEPENDENT: A failure of an item that is not caused by the failure of any other item. A failure that is not dependent. FAILURE, INTERMITTENT: Failure for a limited period of time, followed by the item's recovery of its ability to perform within specified limits without any remedial action. FAILURE MECHANISM: The physical, chemical, electrical, thermal or other process which results in failure. FAILURE MODE: The consequence of the mechanism through which the failure occurs, i.e., short, open, fracture, excessive wear. FAILURE MODE AND EFFECTS ANALYSIS (FMEA): A procedure for analyzing each potential failure mode in a product to determine the results or effects thereof on the product. When the analysis is extended to classify each potential failure mode according to its severity and probability of occurrence, it is called a Failure Mode, Effects, and Criticality Analysis (FMECA).

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS FAILURE, NON-CHARGEABLE: (a) A non-relevant failure. (b) A relevant failure caused by a condition previously not specified as being the responsibility of a given organizational entity. All relevant failures are chargeable to one organizational entity or another. FAILURE, NON-RELEVANT: (a) A failure verified as having been caused by a condition not present in the operational environment. (b) A failure verified as peculiar to an item design that will not enter the operational, or active, inventory. FAILURE, RANDOM: A failure, the occurrence of which cannot be predicted except in a probabilistic or statistical sense. FAILURE RATE: The total number of failures within an item population, divided by the total number of life units expended by that population, during a particular measurement period under stated conditions. FALSE ALARM RATE (FAR): The frequency of occurrence of false alarms over a defined period of measure (e.g., time, cycles, etc.). FALSE ALARM: A fault indicated by BIT or other monitoring circuitry where no fault can be found or confirmed. FAULT: Immediate cause of failure (e.g., maladjustment, misalignment, defect, etc.). FAULT DETECTION (FD): A process which discovers the existence of faults. FAULT ISOLATION (FI): The process of determining the location of a fault to the extent necessary to effect repair. FAULT ISOLATION TIME: The time spent arriving at a decision as to which items caused the system to malfunction. This includes time spent working on (replacing, attempting to repair, and adjusting) portions of the system shown by subsequent interim tests not to have been the cause of the malfunction. FAULT LOCALIZATION: The process of determining the approximate location of a fault. FRACTION OF FAULTS DETECTABLE (FFD): That fraction of all failures that occur over operating time, t, that can be correctly identified through direct observation or other specified means by an operator or by maintenance personnel under stated conditions. FRACTION OF FAULTS ISOLATABLE (FFI): That fraction of all failures that occur over operating time, t, that can be correctly isolated to n or fewer units at a given maintenance level through the use of specified means by maintenance personnel under stated conditions.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS FUNCTIONAL TEST: An evaluation of a product or item while it is being operated and checked under limited conditions without the aid of its associated equipment in order to determine its fitness for use.

-GGOVERNMENT-FURNISHED EQUIPMENT (GFE): An item provided for inclusion in or use with a product or service being procured by the Government. GUIDE SPECIFICATION: This is a type of performance specification prepared by the Government. It identifies standard, recurring requirements that must be addressed when developing new systems, subsystems, equipments, and assemblies. Its structure forces appropriate tailoring to meet user needs.

-HHUMAN ENGINEERING (HE): The application of scientific knowledge to the design of items to achieve effective user-system integration (man-machine interface). HUMAN FACTORS: A body of scientific facts about human characteristics. The term covers all biomedical and psychosocial considerations; it includes, but is not limited to, principles and applications in the areas of human engineering, personnel selection, training, life support, job performance aids, work loads, and human performance evaluation.

-IINACTIVE TIME: That time during which an item is in reserve. (In an inactive inventory). INHERENT AVAILABILITY(Ai): A measure of availability that includes only the effects of an item design and its application, and does not account for effects of the operational and support environment. Sometimes referred to as "intrinsic" availability. INHERENT R&M VALUE: A measure of reliability or maintainability that includes only the effects of an item's design and application, and assumes an ideal operating and support environment. INITIAL ISOLATION LEVEL OF AMBIGUITY: The initial number of possible product subunits, identified by the built-in-test, built-in-test equipment, external test equipment, or manual test procedure, which might contain the failed component. INITIAL ISOLATION: Isolation to the product subunit which must be replaced on line to return the product to operation. A subunit can be a modular assembly, or a component such as a crystal

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS or antenna subsection. In the event that the maintenance concept requires a subunit to be removed, repaired and then replaced in the product, initial isolation includes both isolation to the failed subunit and isolation to the failed and removable portion of the subunit. INTEGRATED DIAGNOSTICS: A structured process which maximizes the effectiveness of diagnostics by integrating pertinent elements, such as testability, automatic and manual testing, training, maintenance aiding, and technical information as a means for providing a cost effective capability to unambiguously detect and isolate all faults known or expected in items and to satisfy system mission requirements. Products of this process are hardware, software, documentation, and trained personnel. INTEGRATED PRODUCT TEAM: A concurrent engineering team made up of individuals representing all relevant disciplines associated with a product's design, manufacturing, and marketing. All members work together using shared knowledge and capabilities to develop and manufacture a product in which requirements are balanced. The individuals must be committed to a common purpose, work to a unified set of requirements, and hold themselves accountable for decisions made and actions taken. INTERCHANGE: Removing the item that is to be replaced, and installing the replacement item. INTERCHANGEABILITY: The ability to interchange, without restriction, like equipments or portions thereof in manufacture, maintenance, or operation. Like products are two or more items that possess such functional and physical characteristics as to be equivalent in performance and durability, and are capable of being exchanged one for the other without alteration of the items themselves or of adjoining items, except for adjustment, and without selection for fit and performance. INTERFACE DEVICE: An item which provides mechanical and electrical connections and any signal conditioning required between the automatic test equipment (ATE) and the unit under test (UUT); also known as an interface test adapter or interface adapter unit. INVENTORY, ACTIVE: The group of items assigned to an operational status. INVENTORY, INACTIVE: The group of items being held in reserve for possible future assignment to an operational status. ISOLATION: Determining the location of a failure to the extent possible. ITEM: A general term used to denote any product, system, material, part, subassembly, set, accessory, shop replaceable assembly (SRA), Shop Replaceable Unit (SRU), Weapon Replaceable Assembly (WRA), Line Replaceable Unit (LRU), etc.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-LLEVELS OF MAINTENANCE: The division of maintenance, based on different and requisite technical skill, which jobs are allocated to organizations in accordance with the availability of personnel, tools, supplies, and the time within the organization. Within the DoD, typical maintenance levels are organizational, intermediate and depot. LIFE CYCLE COST (LCC): The sum of acquisition, logistics support, operating, and retirement and phase-out expenses. LIFE CYCLE PHASES: Identifiable stages in the life of a product from the development of the first concept to removing the product from service and disposing of it. Within the Department of Defense, four phases are formally defined: Concept Exploration; Program Definition and Risk Reduction; Engineering and Manufacturing Development; and Production, Deployment, and Operational Support. Although not defined as a phase, demilitarization and disposal is defined as those activities conducted at the end of a product's useful life. Within the commercial sector, various ways of dividing the life cycle into phases are used. One way is: Customer Need Analysis, Design and Development, Production and Construction, Operation and Maintenance, and Retirement and Phase-out. LIFE PROFILE: A time-phased description of the events and environments experienced by an item throughout its life. Life begins with manufacture, continues during operational use (during which the item has one or more mission profiles), and ends with final expenditure or removal from the operational inventory. LINE REPLACEABLE UNIT (LRU): A unit designed to be removed upon failure from a larger entity (product or item) in the operational environment, normally at the organizational level. LIFE UNITS: A measure of use duration applicable to the item. Measures include time, cycles, distance, rounds fired, attempts to operate, etc. LOCALIZATION: Determining the location of a failure to the extent possible, without using accessory test equipment.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-MMAINTAINABILITY: The relative ease and economy of time and resources with which an item can be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources, at each prescribed level of maintenance and repair. Also, the probability that an item can be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources, at each prescribed level of maintenance and repair. MAINTAINABILITY, MISSION: Maintainability as measured when maintenance is performed during the course of a specified mission profile. A mission-related system maintainability parameter. MAINTENANCE: All actions necessary for retaining an item in or restoring it to a specified condition. MAINTENANCE ACTION: An element of a maintenance event. One or more tasks (i.e., fault localization, fault isolation, servicing and inspection) necessary to retain an item in or restore it to a specified condition. MAINTENANCE, CORRECTIVE: See Corrective Maintenance. MAINTENANCE EVENT: One or more maintenance actions required to effect corrective and preventive maintenance due to any type of failure or malfunction, false alarm or scheduled maintenance plan. MAINTENANCE, MANNING LEVEL: The total number of authorized or assigned personnel to support a given system at specified levels of maintenance. MAINTENANCE, PREVENTIVE: See Preventive Maintenance. MAINTENANCE RATIO: A measure of the total maintenance manpower burden required to maintain an item. It is expressed as the cumulative number of labor hours of maintenance expended in direct labor during a given period of the life units divided by the cumulative number of end item life units during the same period. MAINTENANCE, SCHEDULED: See Scheduled Maintenance MAINTENANCE, UNSCHEDULED: See Unscheduled Maintenance

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS MAINTENANCE TASK: The maintenance effort necessary for retaining an item in, or changing/restoring it to a specified condition. MAINTENANCE TIME: An element of downtime which excludes modification and delay time. MEAN DOWNTIME (MDT): The average time a system is unavailable for use due to a failure. Time includes the actual repair time plus all delay time associated with a repair person arriving with the appropriate replacement parts. MEAN MAINTENANCE TIME: A basic measure of maintainability taking into account maintenance policy. The sum of preventive and corrective maintenance times, divided by the sum of scheduled and unscheduled maintenance events, during a stated period of time. MEAN TIME BETWEEN DEMAND (MTBD): A measure of system reliability related to demand for logistic support. The total number of system life units divided by the total number of system demands on the supply system during a stated period of time. MEAN TIME BETWEEN DOWNING EVENTS: A measure of system reliability related to readiness and availability. The total number of system life units divided by the total number of events which cause the system to be unavailable to initiate its mission(s), over a stated period of time. MEAN TIME BETWEEN CRITICAL FAILURE (MTBCF): A measure of mission or functional reliability. The mean number of life units during which the item performs its mission or function within specified limits, during a particular measurement interval under stated conditions. MEAN TIME BETWEEN FAILURE (MTBF): A basic measure of reliability for repairable items. The mean number of life units during which all parts of the item perform within their specified limits, during a particular measurement interval under stated conditions. MEAN TIME BETWEEN MAINTENANCE (MTBM): A measure of the reliability taking into account maintenance policy. The total number of life units expended by a given time, divided by the total number of maintenance events (scheduled and unscheduled) due to that item. MEAN TIME BETWEEN MAINTENANCE ACTIONS (MTBMA): A measure of the product reliability parameter related to demand for maintenance labor. The total number of product life units, divided by the total number of maintenance actions (preventive and corrective) during a stated period of time. MEAN TIME BETWEEN REMOVALS (MTBR): A measure of the product reliability parameter related to demand for logistic support: The total number of system life units divided by the total number of items removed from that product during a stated period of time. This term 3-12

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS is defined to exclude removals performed to facilitate other maintenance and removals for product improvement. MEAN TIME TO FAILURE (MTTF): A basic measure of reliability for non-repairable items. The total number of life units of an item population divided by the number of failures within that population, during a particular measurement interval under stated conditions. MEAN TIME TO REPAIR (MTTR): A basic measure of maintainability. The sum of corrective maintenance times at any specific level of repair, divided by the total number of failures within an item repaired at that level, during a particular interval under stated conditions. MEAN TIME TO RESTORE SYSTEM (MTTRS): A measure of the product maintainability parameter, related to availability and readiness: The total corrective maintenance time, associated with downing events, divided by the total number of downing events, during a stated period of time. (Excludes time for off-product maintenance and repair of detached components.) MEAN TIME TO SERVICE (MTTS): A measure of an on-product maintainability characteristic related to servicing that is calculated by dividing the total scheduled crew/operator/driver servicing time by the number of times the item was serviced. MISSION RELIABILITY: The measure of the ability of an item to perform its required function for the duration of a specified mission profile. Mission reliability defines the probability that the system will not fail to complete the mission, considering all possible redundant modes of operation. MISSION PROFILE: A time-phased description of the events and environments experienced by an item during a given mission. The description includes the criteria for mission success and critical failures. MISSION TIME: That element of up time required to perform a stated mission profile. MISSION-TIME-TO-RESTORE-FUNCTIONS (MTTRF): A measure of mission maintainability: The total corrective critical failure maintenance time, divided by the total number of critical failures, during the course of a specified mission profile. MODIFICATION TIME: That time during which a product is being modified to enhance or expand functionality, correct a design deficiency, improve safety or reliability through design changes, or to bring the product up to the latest configuration.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-NNON-DEVELOPMENTAL ITEM (NDI): Any previously developed item used exclusively for governmental purposes by a Federal agency, a State or local government, or a foreign government with which the U.S. has a mutual defense cooperation agreement; any such item with minor modifications; and any item fully developed and in production but not yet in use. (See “Buying Commercial and Non-Developmental Items: A Handbook [SD-2, Apr 1996, OUSD/A&T]” or the Federal Acquisition Regulation Parts 6, 10, 11, 12 and 14, for a complete definition and criteria.) NON-DESTRUCTIVE INSPECTION (NDI): Any method used for inspecting an item without physically, chemically, or otherwise destroying or changing the design characteristics of the item. However, it may be necessary to remove paint or other external coatings to use the NDI method. A wide range of technology is usually described as nondestructive inspection, evaluation, or testing (collectively referred to as non-destructive evaluation or NDE). The core of NDE is commonly thought to contain ultrasonic, visual, radiographic, eddy current, liquid penetrant, and magnetic particle inspection methods. Other methodologies, include acoustic emission, use of laser interference, microwaves, magnetic resonance imaging, thermal imaging, and so forth. NON-DETECTABLE FAILURE: Failures at the component, equipment, subsystem, or system (product) level that are identifiable by analysis but cannot be identified through periodic testing or revealed by an alarm or an indication of an anomaly. NOT-OPERATING TIME: That time during which the product is operable according to all indications or the last functional test, but is not being operated.

-OOPERABLE: The state in which an item is able to perform its intended function(s). OPERATIONAL ENVIRONMENT: The aggregate of all external and internal conditions (such as temperature, humidity, radiation, magnetic and electric fields, shock vibration, etc.) either natural or man made, or self-induced, that influences the form, operational performance, reliability or survival of an item. OPERATIONAL R&M: A measure of reliability and maintainability that includes the combined effects of design, installation, quality, environment, operation, maintenance, etc. on an item. OPERATIONAL READINESS: The ability of a military unit to respond to its operation plan(s) upon receipt of an operations order. (A function of assigned strength, item availability, status, or supply, training, etc.).

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS OPERATIONAL TEST AND EVALUATION (OT&E): Test and evaluation which focuses on the development of optimum tactics, techniques, procedures, and concepts for products and items, evaluation of reliability, maintainability and operational effectiveness, and suitability of products and items under realistic operational conditions.

-PPERCENT ISOLATION TO A GROUP OF RIs: The percent of time that detected failures can be fault isolated to a specified ambiguity group of size n or less, where n is the number of replaceable items (RIs). PERCENT ISOLATION TO A SINGLE RI: The percent of time that detected failures can be fault isolated to exactly one replaceable item (RI). PERFORMANCE SPECIFICATION (PS): requirements for an item. A design document stating the functional

PERFORMANCE-BASED REQUIREMENTS (SPECIFICATION): Requirements that describe what the product should do, how it should perform, the environment in which it should operate, and interface and interchangeability characteristics. They should not specify how the product should be designed or manufactured. PREDICTED: That which is expected at some future time, postulated on analysis of past experience and tests. PROCESS ACTION TEAM (PAT): A group of individuals with complementary skills, committed to a common purpose, set of performance goals, and approach for which they hold themselves accountable, who work together using shared knowledge and capabilities to improve business processes. PROGRAM-UNIQUE SPECIFICATION. This type of Government specification, also called a system specification, establishes requirements for items used for a particular weapon system or program. Little potential exists for the use of the document in other programs or applications. It is written as a performance specification, but it may include a blend of performance and detail design type requirements. PREPARATION TIME: The time spent obtaining, setting up, and calibrating maintenance aids; warming up equipment; etc. PREVENTIVE MAINTENANCE (PM): All actions performed to retain an item in specified condition by providing systematic inspection, detection, and prevention of incipient failures.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-QQUALIFICATION TEST: A test conducted under specified conditions, by or on behalf of the customer, using items representative of the production configuration, to determine if item design requirements have been satisfied. Serves as a basis for production approval. Also known as a Demonstration Test.

-RREACTION TIME: The time between the instant a product is required to perform a function or mission and the time it is ready to perform that function or mission. It is the time needed for a product to be transitioned from a non-operating state to an operating state. REASSEMBLY: Assembling the items that were removed during disassembly and closing the reassembled items. RECONDITIONING: See Burn-In. REDUNDANCY: The existence of more than one means for accomplishing a given function. Each means of accomplishing the function need not necessarily be identical. The two basic types of redundancy are active and standby. Active Redundancy - Redundancy in which all redundant items operate simultaneously. Standby Redundancy - Redundancy in which some or all of the redundant items are not operating continuously but are activated only upon failure of the primary item performing the function(s). RELEVANT: That which can occur or recur during the life of an item. RELIABILITY: (1) The duration or probability of failure-free performance under stated conditions. (2) The probability that an item can perform its intended function for a specified interval under stated conditions. (For non-redundant items this is equivalent to definition (1). For redundant items this is equivalent to definition of mission reliability.) RELIABILITY-CENTERED MAINTENANCE (RCM): A disciplined logic or methodology used to identify preventive and corrective maintenance tasks to realize the inherent reliability of equipment at a minimum expenditure of resources. RELIABILITY GROWTH: The improvement in reliability that results when design, material, or part deficiencies are revealed by testing and eliminated or mitigated through corrective action.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS REPAIR TIME: The time spent replacing, repairing, or adjusting all items suspected to have been the cause of the malfunction, except those subsequently shown by interim test of the system not to have been the cause. REPAIRABILITY: The probability that a failed item will be restored to operable condition within a specified time of active repair. REPAIRABLE ITEM: An item which, when failed, can be restored by corrective maintenance to an operable state in which it can perform all required functions REPLACEABLE ITEM (RI) or REPLACEABLE UNIT (RU): An item, unit, subassembly, or part which is normally intended to be replaced during corrective maintenance after its failure. REQUEST FOR PROPOSAL (RFP): A letter or document sent to suppliers asking to show how a problem or situation can be addressed. Normally the supplier's response proposes a solution and quotes a price. Similar to a Request for Quote (RFQ), although the RFQ is usually used for products already developed.

-SSCHEDULED MAINTENANCE: Periodic prescribed inspection and servicing of products or items accomplished on the basis of calendar, mileage or hours of operation. Included in Preventive Maintenance. SCREENING: A process for inspecting items to remove those that are unsatisfactory or likely to exhibit early failure. Inspection methods includes visual examination, physical dimension measurement, and functional performance measurement under specified environmental conditions. SERVICEABILITY: The relative ease with which an item can be serviced (i.e., kept in operating condition). SERVICING: The performance of any act needed to keep an item in operating condition, (i.e. lubricating, fueling, oiling, cleaning, etc.), but not including preventive maintenance of parts or corrective maintenance tasks. SINGLE-POINT FAILURE: A failure of an item that causes the system to fail and for which no redundancy or alternative operational procedure exists. SNEAK CIRCUIT ANALYSIS: An analytical procedure for identifying latent paths that cause occurrence of unwanted functions or inhibit desired functions, assuming all components are operating properly.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS STANDARD PERFORMANCE SPECIFICATION (SPS): A type of specification that establishes requirements for military-unique items used in multiple programs or applications. STORAGE LIFE: The length of time an item can be stored under specified conditions and still meet specified operating requirements. Also called shelf life. SUBSYSTEM: A combination of sets, groups, etc. which performs an operational function within a product (system) and is a major subdivision of the product. (Example: Data processing subsystem, guidance subsystem). SUPPLY DELAY TIME: The time between the demand on the supply system for a part or item to repair a product, or for a new product to replace a failed product, and the time when it is available. SYSTEM: A composite of equipment and skills, and techniques capable of performing or supporting an operational role, or both. A complete system includes all equipment, related facilities, material, software, services, and personnel required for its operation and support to the degree that it can be considered self-sufficient in its intended operational environment. SYSTEM DOWNTIME: The time interval between the commencement of work on a system (product) malfunction and the time when the system has been repaired and/or checked by the maintenance person, and no further maintenance activity is executed. SYSTEM EFFECTIVENESS: (a) For repairable systems and items: the probability that a system can successfully meet an operational demand within a given time when operated under specified conditions. (b) For "one-shot" devices and non-repairable items: the probability that the system will operate successfully when called upon to do so under specified conditions. SYSTEM FINAL TEST TIME: The time spent confirming that a system is in satisfactory operating condition (as determined by the maintenance person) following maintenance. It is possible for a system final test to be performed after each correction of a malfunction. SYSTEM R&M PARAMETER: A measure of reliability or maintainability in which the units of measurement are directly related to operational readiness, mission success, maintenance labor costs, or logistics support costs.

-TTESTABILITY: A design characteristic which allows an item's status (operable, inoperable, or degraded) be determined and faults within the item to be isolated in a timely manner.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS TEST, ANALYZE, AND FIX (TAAF): A synonym for reliability growth in which the three main elements (test, analyze deficiencies, and take corrective action) for achieving reliability growth are identified. TEST, MEASUREMENT, AND DIAGNOSTIC EQUIPMENT (TMDE): Any product or item used to evaluate the condition of another product or item to identify or isolate any actual or potential failures. TEST POINT: A jack or similar fitting to which a test probe is attached for measuring a circuit parameter or wave form. TIME: Time is a fundamental element used in developing the concept of reliability and is used in many of the measures of reliability. Determining the applicable interval of time for a specific measurement is a prerequisite to accurate measurement.. In general, the interval of interest is calendar time, but this can be broken down into other intervals as shown in Figure 3-1.
Calendar Time

Active Time

Up Time

Downtime

Inactive Time Includes time in storage or supply pipeline

Mission Time

Alert Time

Reaction Time

Not Operating Time

Maintenance Time

Modification Time

Delay Time

Time to Restore Functions During Mission

PM Time

CM Time

Supply Delay Time

Admin Time

FIGURE 3-1: INTERVALS OF TIME TIME, TURN AROUND: That element of maintenance time needed to replenish consumables and check out an item for recommitment. TOTAL SYSTEM DOWNTIME: The time interval between the reporting of a system (product) malfunction and the time when the system has been repaired and/or checked by the maintenance person, and no further maintenance activity is executed.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-UUNIT UNDER TEST (UUT): A UUT is any product or item (system, set, subsystem, assembly or subassembly, etc.) undergoing testing or otherwise being evaluated by technical means. UNSCHEDULED MAINTENANCE: suspected failure. Corrective maintenance performed in response to a

UPTIME: That element of ACTIVE TIME during which an item is in condition to perform its required functions. (Increases availability and dependability). UPTIME RATIO: A composite measure of operational availability and dependability that includes the combined effects of item design, installation, quality, environment, operation, maintenance, repair and logistic support: The quotient of uptime divided by the sum of uptime and downtime.) USEFUL LIFE: The number of life units from manufacture to when the item has an unrepairable failure or unacceptable failure rate. Also, the period of time before the failure rate increases due to wearout. UTILIZATION RATE: The planned or actual number of life units expended, or missions attempted during a stated interval of calendar time.

-VVERIFICATION: The contractor effort to: (1) determine the accuracy of and update the analytical (predicted) data; (2) identify design deficiencies; and (3) gain progressive assurance that the required performance of the item can be achieved and demonstrated in subsequent phases. This effort is monitored by the procuring activity from date of award of the contract, through hardware development from components to the configuration item (CI).

-WWEAROUT: The process that results in an increase of the failure rate or probability of failure as the of number of life units increases.

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS 3.3 List of Abbreviations and Acronyms

-AAi Ao ACAT AGREE ANSI ARINC ASIC ATE AVIP Availability, Inherent (or intrinsic) Availability, Operational Acquisition Category Advisory Group on Reliability of Electronic Equipment American National Standards Institute Aeronautical Radio Incorporated Application Specific Integrated Circuit Automatic Test Equipment Avionics Integrity Program

-BBIT BITE BOL Built-In Test Built-In Test Equipment Beginning of Life

-CCAD CAM CDR CDRL CI CID CM CND COTS CUT Computer Aided Design Computer Aided Manufacturing Critical Design Review Contract Data Requirements List Configuration Item Commercial Item Description Corrective Maintenance Cannot Duplicate Commercial-Off-The-Shelf Circuit Under Test

-DDAR DARPA DESC DLA DoD DoDISS DOE Defense Acquisition Reform Defense Advanced Research Project Agency Defense Electronic Supply Center Defense Logistics Agency Department of Defense Department of Defense Index of Standards and Specifications Design of Experiments 3-21

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS DT DTIC DMH/MA DT&E Development Test Defense Technical Information Center Direct Manhours per Maintenance Action Development Test and Evaluation

-EECP EDIF EHC EMC EMD EMI EMP EOL ESD ESS ETE Engineering Change Proposal Electronic Data Interchange Format Explosive Hazard Classification Electromagnetic Compatibility Engineering and Manufacturing Development Electromagnetic Interference Electromagnetic Pulse End of Life Electrostatic Discharge Environmental Stress Screening External Test Equipment

-FFA FAR FEA FMEA FMECA FD FD&I FEA FFD FFI FI FL FFD FFI FH F3I FPGA FRACAS FTA False Alarm False Alarm Rate Finite Element Analysis Failure Modes and Effects Analysis Failure Modes, Effects, and Criticality Analysis Fault Detection Fault Detection and Isolation Finite Element Analysis Fraction of Faults Detectable Fraction of Faults Isolatable Fault Isolation Fault Localization Fraction of Faults Detected Fraction of Faults Isolated Flying Hours Form, Fit, Function, and Interface Field Programmable Gate Arrays Failure Reporting and Corrective Action System Fault Tree Analysis

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-GGaAs GEM GIDEP GPTE GS Gallium Arsenide Generalized Emulation of Microcircuits Government-Industry Data Exchange Program General Purpose Test Equipment Guide Specification

-HHALT HAST HCR HE Highly Accelerated Life Test Highly Accelerated Stress Test Human Cognitive Reliability Human Engineering

-IIC IEC IEEE ILS IOT&E IPD IPDT Integrated Circuit International Electrotechnical Commission Institute of Electrical and Electronic Engineers Integrated Logistics Support Initial Operational Test and Evaluation Integrated Product Team Integrated Product Development Team

-LLCC LRM LRU LSA Life Cycle Cost Line Replaceable Module Line Replaceable Unit Logistics Support Analysis

-MMA MCM MDT MIMIC MOS MOV MPCAG MR Maintenance Action Multichip Module Mean Downtime Monolithic Microwave Millimeter Wave Integrated Circuit Metal Oxide Semiconductor Metal Oxide Varistor Military Parts Control Advisory Group Mission Reliability or Maintenance Rate 3-23

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS MTBF MTBCF MTBD MTBDE MTBF MTBM MTTF MTTR MTTRS MTTS MVT Mean Time Between Failure Mean Time Between Critical Failure Mean Time Between Demand Mean Time Between Downing Events Mean Time Between Failure Mean Time Between Maintenance Mean Time To Failure Mean Time To Repair Mean Time To Restore System Mean Time To Service Majority Vote Comparator

-NNDI Non-Developmental Item or Non-Destructive Inspection

-OO&M O&SHA OHHA OT&E Operation and Maintenance Operating and Support Hazard Analysis Occupational Health Hazard Assessment Operational Test and Evaluation

-PPAT PCB PDR PEM PHA PHL PLD PM PMP PPL PPSL PRDR PSP P&V Process Action Team Printed Circuit Board Preliminary Design Review Plastic Encapsulated Microcircuit Preliminary Hazard Analysis Preliminary Hazard List Programmable Logic Device Preventive Maintenance Parts Management Program Preferred Parts List Program Parts Selection List Preproduction Reliability Design Review Performance Shaping Factor Power and Voltage

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-QQFD QML Quality Function Deployment Qualified Manufacturers List

-RRAM R&D R/R RAC RADC RCM RF RFP RGA RGT RISC RIW RL RMS RPN RTOK R&M Reliability, Availability, Maintainability Research and Development Remove and Replace Reliability Analysis Center Rome Air Development Center Reliability Centered Maintenance Radio Frequency Request for Proposal Residual Gas Analysis Reliability Growth Test Reduced Instruction Set Computer Reliability Improvement Warranty Rome Laboratory Reliability, Maintainability, Supportability Risk Priority Number Retest OK Reliability and Maintainability

-SSAE SCA SCR SHA SLI SMD SOO SOW SPC SPS SRA SRU SSHA SSG SSWG Society of Automotive Engineers Sneak Circuit Analysis Silicon Controlled Rectifier System Hazard Analysis Success Likelihood Index Surface Mount Device Statement of Objectives Statement of Work Statistical Process Control Standard Performance Specification Shop Replaceable Assembly Shop Replaceable Unit Subsystem Hazard Analysis System Safety Group System Safety Working Group 3-25

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SECTION 3: DEFINITIONS OF TERMS, ACRONYMS AND ABBREVIATIONS

-TTAAF TMDE TQM TRB TTF Test, Analyze, and Fix Test, Measurement, and Diagnostic Equipment Total Quality Management Technology Review Board Time to Failure

-UUR UUT Uptime Ratio or Utilization Rate Unit Under Test

-VVHDL VHSIC VHSIC Hardware Description Language Very High Speed Integrated Circuit

-WWSEIAC WCA WCCA WRA WUC Weapon System Effectiveness Industry Advisory Committee Worst Case Analysis Worst Case Circuit Analysis Weapon Replaceable Assembly Work Unit Code

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SECTION 4: GENERAL STATEMENTS 4.0 4.1 GENERAL STATEMENTS Introduction and Background

For all but the most recent years of human history, the performance expected from man’s implements was quite low and the life realized was long, both because it just happened to be so in terms of man’s lifetime and because he had no reason to expect otherwise. The great technological advances, beginning in the latter half of the twentieth century, have been inextricably tied to more and more complex implements or devices. In general, these have been synthesized from simpler devices having a satisfactory life. It is a well known fact that any device which requires all its parts to function will always be less stable than any of its parts. Although significant improvements have been made in increasing the lives of basic components for example, microelectronics - these have not usually been accompanied by corresponding increases in the lives of equipment and systems. In some cases, equipment and system complexity has progressed at so rapid a pace as to negate, in part, the increased life expected from use of the longer-lived basic components. In other cases, the basic components have been misapplied or overstressed so that their potentially long lives were cut short. In still other cases, management has been reluctant to devote the time and attention necessary to ensure that the potentially long lives of the basic components were achieved. The military services, because they tended to have the most complex systems and hence the most acute problems, provided the impetus to the orderly development of the discipline of reliability engineering. It was they who were instrumental in developing mathematical models for reliability, as well as design techniques to permit the quantitative specification, prediction and measurement of reliability. Reliability engineering is the doing of those things which insure that an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects: (1) (2) paying attention to detail handling uncertainties

The traditional, narrow definition of reliability is “the probability that an item can perform its intended function for a specified interval under stated conditions.” This narrow definition is applicable largely to items which have simple missions, e.g., equipment, simple vehicles, or components of systems. For large complex systems (e.g., command and control systems, aircraft weapon systems, a squadron of tanks, naval vessels), it is more appropriate to use more sophisticated concepts such as “system effectiveness” to describe the worth of a system. A more precise definition of system effectiveness and the factors contributing to it are presented in Section 4.3. For the present, it is sufficient to observe that 4-1

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SECTION 4: GENERAL STATEMENTS system effectiveness relates to that property of a system output which was the real reason for buying the system in the first place - namely, the carrying out of some intended function. If the system is effective, it carries out this function well. If it is not effective, attention must be focused on those system attributes which are deficient. 4.2 The System Engineering Process

In recent years, the word “system” has come to include: (1) (2) (3) (4) (5) (6) (7) The prime mission equipment The facilities required for operation and maintenance The selection and training of personnel Operational and maintenance procedures Instrumentation and data reduction for test and evaluation Special activation and acceptance programs Logistic support programs

System engineering is the application of scientific, engineering, and management effort to: (1) Transform an operational need into a description of system performance parameters and a system configuration through the use of an iterative process of definition, synthesis, analysis, design, test, and evaluation. Integrate related technical parameters and assure compatibility of all physical, functional, and program interfaces in a manner that optimizes the total system design.

(2)

(3)

Integrate reliability, maintainability, safety, survivability (including electronic warfare considerations), human factors, and other factors into the total engineering effort.

From the system management viewpoint, system engineering is but one of five major activities required to develop a system from Conceptual Exploration through the subsequent phases of Program Definition and Risk Reduction; Engineering and Manufacturing Development (EMD); and Production, Fielding/Deployment, and Operational Support. (These are the major phases defined in DoD 5000.2-R). These five activities (procurement and production, program control, configuration management, system engineering, and test and deployment management), must

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SECTION 4: GENERAL STATEMENTS perform their general functions within each of the system evolutionary phases, and their relationships to one another are summarized in Figure 4.2-1. 4.2.1 Systems Engineering and IPTs

Integrated Product Teams (IPTs) are a pragmatic means of implementing a true systems engineering approach. As part of Defense Acquisition Reform (see Section 12), then Secretary of Defense William Perry instituted the Integrated Product/Process Development (IPPD) approach to system acquisition. It is a systematic approach to the integrated, concurrent design of products and their related processes, including manufacturing and life cycle support. Essential to the IPPD approach is the use of IPTs. These teams are multi-functional groups of individuals who manage and integrate critical processes. All too often in the past, each phase of system acquisition was dominated by one functional group. For example, during design, the design engineers were the primary “players.” Although some interaction between the designers and other functional groups occurred, it did so in an iterative, serial fashion. Sometime prior to the beginning of production, the design was ìhanded off? to the manufacturing organization which was supposed to design the processes needed to produce the system. Also, after the design was “frozen,” the support community was given the task of planning for the support of the system. This essentially sequential approach led to problems of poor producibility, high manufacturing costs, slipped schedules, high support requirements, and so forth. Efforts were made to solve this “stovepiping” of functions. In the late 1970’s, Integrated Logistics Support Offices (ILSOs) were co-located with and as part of major system program offices. One objective of these co-located ILSOs was to influence the design to enhance inherent supportability. In the 1970’s and 1980’s, computer-aided design (CAD) and computer-aided manufacturing (CAM) were introduced as tools for linking the various functional disciplines together. With the advent of IPTs, however, came a multi-disciplined approach to decisionmaking. By empowering these IPTs to make decisions in a collaborative manner, many of the problems of stovepiping are being overcome. Together with tools such as CAD/CAM, IPTs are proving to be an effective way of implementing the systems engineering concept and finding the optimal balance among competing requirements under the constraints of cost and schedule. 4.2.2 The Four Steps of Systems Engineering

System engineering consists of four steps in an interacting cycle (Figure 4.2-2). Step 1 considers threat forecast studies, doctrinal studies, probable military service tasks, and similar sources of desired materiel and system objectives; then it translates them into basic functional requirements or statements of operation. The usual result of Step 1 is a set of block diagrams showing basic functional operations and their relative sequences and relationships. Even though hardware may

4-3

4-4
Procurement & Production Management Procurement Plan Follow-up Production Development Construction & Production Contract Program Control Management Transition Agreements Preliminary System Program Plan System Program Schedules & Allocations Define Program Baselines Configuration Management General System Specs for Contract End Items (CEI) FACI* & Detail Specs for CEI** (System Configuration Baseline) Program Change Requests & Modifications System in Operation Disposition of System System Engineering Management Design Requirements Baseline Defined Detailed Design Upgrade System Engineering Test & Deployment Management Test & Deployment Plan Developmental and Operational Production PROGRAM DEFINITION AND RISK REDUCTION ENGINEERING AND MANUFACTURING DEVELOPMENT PRODUCTION DEPLOYMENT

SECTION 4: GENERAL STATEMENTS

Requirements

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System Planning

Determine General Objectives, Feasibility

Technology

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*FACI = Functional and Configuration Item **CEI = Configuration End Item

FIGURE 4.2-1: SYSTEM MANAGEMENT ACTIVITIES

CONCEPT EXPLORATION

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SECTION 4: GENERAL STATEMENTS help shape the basic system design, it is not specifically included in Step 1. Step 1 is intended to form a first hypothesis as a start toward the eventual solution. In Step 2, the first hypothesis is evaluated against constraints such as design, cost, and time and against specific mission objectives to create criteria for designing equipment, defining intersystem interfaces, defining facilities, and determining requirements for personnel, training, training equipment and procedures. Step 3 consists of system design studies that are performed concurrently with Steps 2 and 4 to: (1) (2) Determine alternate functions and functional sequences Establish design personnel, training and procedural data requirements imposed by the functions Find the best way to satisfy the mission requirements Select the best design approach for integrating mission requirements into the actual hardware and related support activities

(3) (4)

Normally, the studies in Step 3 involve tradeoffs where data are in the form of schematic block diagrams, outline drawings, intersystem and intrasystem interface requirements, comparative matrices, and data supporting the selection of each approach. Some of the scientific tools used in the system design studies in Step 3 are: probability theory, statistical inference, simulation, computer analysis, information theory, queuing theory, servomechanism theory, cybernetics, mathematics, chemistry, and physics. Step 4 uses the design approach selected in Step 3 to integrate the design requirements from Step 2 into the Contract End Items (CEI’s). The result of Step 4 provides the criteria for detailed design, development, and test of the CEI based upon defined engineering information and associated tolerances. Outputs from Step 4 are used to: (1) (2) Determine intersystem interfaces Formulate additional requirements and functions that evolve from the selected devices or techniques Provide feedback to modify or verify the system requirements and functional flow diagrams prepared in Step 1

(3)

4-5

4-6
Step 1 Analyze Functions & Translate into Requriements for Design, Facilities, Personnel, Training, & Prcedures Step 2 Step 4 Integrate Requirements into Contract End items, training & Technical Procedures Step 3 System/Design Engineering Tradeoff Studies to Determine Requirements & Design Approach

SECTION 4: GENERAL STATEMENTS

Translate System Requirements into Functional Requirements

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FIGURE 4.2-2: FUNDAMENTAL SYSTEM PROCESS CYCLE

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SECTION 4: GENERAL STATEMENTS When the first cycle of the system engineering process is completed, the modifications, alternatives, imposed constraints, additional requirements, and technological problems that have been identified are recycled through the process with the original hypothesis (initial design) to make the design more practical. This cycling is continued until a satisfactory design is produced, or until available resources (time, money, etc.) are expended and the existing design is accepted, or until the objectives are found to be unattainable. Other factors that are part of the system engineering process - such as reliability, maintainability, safety, and human factors - exist as separate but interacting engineering disciplines and provide specific inputs to each other and to the overall system program. Pertinent questions at this point might be: “How do we know when the design is adequate?” or “How is the effectiveness of a system measured?” The answers to these questions lead to the concept of system effectiveness. 4.3 System Effectiveness

System effectiveness is a measure of the ability of a system to achieve a set of specific mission requirements. It is a function of readiness (or availability), and mission success (or dependability). Cost and time are also critical in the evaluation of the merits of a system or its components, and must eventually be included in making administrative decisions regarding the purchase, use, maintenance, or discard of any equipment or system. The operational effectiveness of a system obviously is influenced by the way the equipment was designed and built. It is, however, just as influenced by the way the equipment is used and maintained; i.e., system effectiveness is influenced by the designer, production engineer, maintenance man, and user/operator. The concepts of availability and dependability illustrate these influences and their relationships to system operational effectiveness. The following are the definitions of these concepts: (1) Availability - A measure of the degree to which an item is in an operable and committable state at the start of a mission, when the mission is called for at an unknown (random) time. Dependability - A measure of the degree to which an item is operable and capable of performing its required function at any (random) time during a specified mission profile, given item availability at the start of the mission. (This definition is significantly different than the definition of dependability used by most other US and international organizations dealing with reliability e.g., the International Electrotechnical Commission (IEC) and the Society of Automotive Engineers (SAE). The IEC defines Dependability in publication IEC 50 Chapter 191 as: “The collective term used to describe the availability performance and its influencing factors: reliability

(2)

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SECTION 4: GENERAL STATEMENTS performance, maintaintability performance and maintenance support performance.” As such, its use is restricted to general descriptions in non-quantitative terms). Dependability is related to reliability; the intention was that dependability would be a more general concept then reliability. 4.3.1 R/M Considerations in System Effectiveness

From a system effectiveness viewpoint, reliability and maintainability jointly provide system availability and dependability. Increased reliability directly contributes to system uptime, while improved maintainability reduces downtime. If reliability and maintainability are not jointly considered and continually reviewed, serious consequences may result. With military equipment, failures or excessive downtime can jeopardize a mission and possibly cause a loss of lives. Excessive repair time and failures also impose burdens on logistic support and maintenance activities, causing high costs for repair parts and personnel training, expenditure of many manhours for actual repair and service, obligation of facilities and equipment to test and service, and to movement and storage of repair parts. From the cost viewpoint, reliability and maintainability must be evaluated over the system life cycle, rather than merely from the standpoint of initial acquisition. An effective design approach to reliability and maintainability can reduce the cost of upkeep. Both reliability and maintainability are important considerations for the user of the system, although maintainability is probably more important from the point of view of most users. Although frequent system failures may be an annoyance, if each failure can be repaired in a very short time so that the system has a high availability, and the maintenance costs are reasonable, then the poor reliability may be acceptable. For example, if failures occur on the average of every fifteen minutes but can be repaired in a microsecond, at acceptable cost, the user will not be too concerned. On the other hand, if repair of a failure takes hours or days, the user has a nonavailable weapon system which may have a significant effect on the operational commander’s readiness posture. 4.4 Factors Influencing System Effectiveness 4.4.1 Equipment of New Design

A typical history of the development of a new equipment would reveal a number of interesting steps in the progression from original concept to acceptable production model. These steps are particularly marked if the equipment represents a technical innovation, i.e., if it “pushes the state of the art” by introducing entirely new functions or by performing established functions in an entirely new way. Starting with a well- defined operational need, the research scientist, designer, reliability engineer, statistician, and production engineer all combine their talents to execute a multitude of operations leading to one ultimate objective: the production of an equipment that 4-8

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SECTION 4: GENERAL STATEMENTS will perform as intended, with minimum breakdowns and maximum speed of repair. All this must be done at minimum cost and usually within an accelerated time schedule. These program requirements are severe, to say the least. In order to meet them, many compromises are required. One of the first of these compromises is often a sharp curtailment in the basic research time allotted to the job of proving the feasibility of the new design. After only brief preliminary study, a pilot model of the equipment is built. With luck, it will work; but it is likely to be somewhat crude in appearance, too big and too heavy, not well-designed for mass production, subject to frequent failure, and di

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