Reliability (R) is the probability an item (e.g., system, subsystem, or component) will perform its intended function with no failure for a stated period of time (or number of demands or load) under stated environmental conditions. Other words, reliability is the probability an item will be in an uptime state (i.e., fully operational or ready to perform) for a stated mission.

Maintainability (M) is the probability a failed item will be restored or repaired to a specified condition within a given period of time. Other words, maintainability is the probability an item in a downtime state will be returned to an uptime state within a given period of time.

Availability (A), a function of Reliability and Maintainability (R&M), is the probability a repairable item will perform its intended function at a given point in time (or over a specified period of time) when operated and maintained in a prescribed manner. Other words, availability is the probability of an item’s mission readiness, an uptime state with the likelihood of a recoverable downtime state.

Ideally from an RMA Plan, the RMA team performs three major functions, namely, (1) Design for RMA, (2) RMA verification, and (3) Analytical physics. For specific RMA tasks click here.

Basic Concepts

• Reliability
• Reliability Discipline
• Availability
• Risk
• Risk, Failure Probability, and Failure Rate
• Mission Assurance
• Probability & Verification (expanded)

Presentations and Training

• Metrics for Managed Organizations
• Tutorial: Quantitative RMA for the Practitioner
• Examples: Quantitative Reliability in Action
• Availability: Concepts and Principles for the Practitioner
• NASA Safety Center STEP (NASA internal)
• Other

Organizations

• NASA Engineering Network (NEN)
• NASA Office of Safety and Mission Assurance (OSMA)
• NASA Safety Center (NSC)
• NASA R&M Community of Practice (NASA internal)
• DoD, OUSD (R&E) R&M Engineering
• Other

History

• Short History of Reliability, by James McLinn
• History of Reliability and Quality Assurance at KSC
• Design Reliability (RBDA & FMEA), KSC Engineering 1974 (NASA internal)
• KSC Component Failure Rates 1972

Apollo Program

• Reliability in the Apollo Program
• Technical Manual: Apollo Reliability (NASA internal)
• Dr. Kurt H. Debus: Contributions, Legacy, and Challenges

• NPD 8720 NASA Reliability and Maintainability (R&M) Program Policy
• NASA-STD-8729 NASA R&M Standard for Spaceflight and Support Systems (URL fixed)
• NPR 8705 Human-Rating Requirements for Space Systems
• NPD 8700 NASA Policy for Safety and Mission Success
• NPR 8705 Risk Classification for NASA Payloads
• Launch Svcs Risk Mitigation for NASA-Owned/Sponsored Payloads/Missions
• Developing Performance-Based Reliability Requirements

• Reliability Standards Search (Searches inside standard using key words)
• Military Handbooks and Standards Related to Reliability
• NASA Reliability Preferred Practices for Design and Test, Tech Memo 4322A, Feb 1999
• NASA Lessons Learned (URL fixed)
• NASA Technical Standards System

Discrete (Event-Based, Demand-Based, Failure on Demand)

• Failure probability for demand based data with and without failures (Classical & Bayesian)
• Binomial (Prob. of x or more events in n attempts; includes tutorial)
• Poisson Process (Prob. of r or less events in a time interval & Spare Quantity Determination)

Continuous (Time-Based, Failure while Operating)

• Failure rate for time based data with zero failures (Classical and Bayesian)
• Use parameters to make and compare two Weibull (or lognormal) distributions
• Tools to convert time-based data to a probability distribution (NASA internal)
• RMA Quantitative Relationships and Allocate Availability
• RMA dashboard

Physics Based

• Stress-Strength Interference (Load vs. Capacity)
• Arrhenius (failures accelerated by increases in temperature)

Tool Suites and Reports

• Reliability Analytics Toolkit
• Dr. Bob's Reliability Calculator
• Relyence (NASA internal) (new)
• Windchill Risk and Reliability (WRR) (NASA internal)
• Integrated Design & Assurance System (IDAS)
• Integrated Design & Assurance System (IDAS) (NASA internal)
• SMA Toolbox-Collection of Reports (NASA internal)

Decision Making

• A Pyramid of Decision Approaches
• Dept of Energy Guidebook to Decision-Making Methods
• Decision Analysis in One Chart
• NASA Risk-Informed Decision Making Handbook

Systems Engineering

• NASA Systems Engineering "Toolbox" (Tip: Start with Appendix B)
• NASA Systems Engineering Handbook
• NASA System Safety Handbooks
• Interface Definition & Control
• Digital Engineering, MBSE, and MBMA
• Establishing & Balancing High-Level S, R, & M Requirements
• Allocating Reliability Given Requirements as a Fault Tree

Reliability Physics

• Introduction-paper, RAMS 2013 (NASA internal)
• Introduction-slides, RAMS 2013 (NASA internal)
• US Navy Reliability Prediction of Mechanical Equipment
• Mechanical Design Reliability Handbook (from ASQ Reliability Division)

Success-Space Modeling

• Functional Flow Block Diagram (FFBD)
• RMA Analysis via RBDA
• Reliability Block Diagram (RBD) (NASA internal)

Failure-Space Modeling

• Failure Mode Effects and Criticality Analysis (FMECA)
• NASA Fault Tree Handbook with Aerospace Applications
• NASA Probabilistic Risk Assessment (PRA) Guidebook

Failure-Data Resources

• Automated Databook for Failure Rates, Modes, and Mechanisms
• Reactor Operational Experience and Databases
• Other Data Resources From NRC

Bayesian Method

• Summary: Process and Comparison
• NASA Handbook on Bayesian Inference (URL fixed)

Uncertainty

• Summary: Concepts & Principles
• NUREG-1855, Vol 1, Report

Miscellaneous

• Laplace Test
• Trending US Landfalling Hurricanes via the Laplace Test
• NASA Reliability Centered Maintenance (RCM)
• Root Cause Analysis (RCA)
• NASA JSC Work Process Improvement (NASA internal)