Presentation on theme: "27 June 2002 1 Overview of AIAA Proposed Project to Develop a Reliability Program Data Transfer Format Standard A Quick Look at the Major Problems Affecting."— Presentation transcript:
27 June Overview of AIAA Proposed Project to Develop a Reliability Program Data Transfer Format Standard A Quick Look at the Major Problems Affecting R&M Assessments in Today’s Space Industry and How a New Standard Might Provide a Practical Solution for the Future Tyrone Jackson; Working Group Coordinator
27 June Distant Background Data collected in 2000 and 2001 to evaluate top-10 Reliability Program problems and causes –Surveyed several Reliability Engineering experts working for NASA and private sector –Participated in development of a IEEE Reliability Program Standard, a IEEE Reliability Prediction Guide, and a SAE FMECA Guide (Draft) Paper published in January 2001 titled: Finding Answers to Space Industry’s Top-10 Reliability Problems Evaluated AIAA Collection of Preferred Space-Related Standards (CPSRS) Project in 2000 and 2001 –Concluded CPSRS Project’s output would provide little value to Reliability community –AIAA cancelled project in 2001
27 June Recent Background In October 2001, Dr. Patrick Larter, President of Society of Reliability Engineers (SRE), requested a plan for reactivating Los Angeles Chapter of SRE In November 2001, Mike Canga of NASA Johnson Space Center expressed a strong interest in requiring that all R&M assessment tools used in development of production version of Crew Return Vehicle (CRV) be compliant with a Data Transfer Format (DTF) standard –Standard should provide a single framework for linking different R&M assessment tools In January 2002, Tyrone Jackson received approval from SRE Board of Directors to form a working group to write a R&M DTF standard
27 June Recent Background (Continued) In March 2002, Tyrone coordinated first bi-weekly teleconference meeting of working group. WG participants come from Aerospace, TRW, Boeing, Spectrum Astro, Northrop Grumman, Cal State Long Beach Graduate Engineering College, and three R&M assessment tool developers In June 2002, Jim French of AIAA informed Tyrone that AIAA Standards Board would vote in August 2002 to sponsor WG to write draft standard –AIAA sanctioning is contingent on draft standard being renamed, “Space Systems - Data Transfer Formats Standard”
27 June Commercial Reliability Standards Failed to Meet Needs of Space Community Commercial reliability standards provide inadequate guidance for establishing, implementing, and monitoring High-Reliability Programs for space systems –Several commercial Reliability Program standards were published by IEEE, SAE, and IEC, but effectiveness of Space Systems Reliability Programs has steadily declined since military standards were discontinued in 1994 –Commercial standards provide no guidance for selecting appropriate reliability assessment methods (or tools) for specific objectives of Space Systems Engineering Process –Commercial standards do not define a consistent criteria for implementing or evaluating reliability assessment methods (or tools)
27 June Cluster of Major Failures in Exposed Reliability Program Weakness FAILED SPACE & LAUNCH VEHICLE MISSIONSDATE OF FAILURE Titan IV A-20/Centaur08/12/98 Titan IV B-27/Inertial Upper Stage04/09/99 Titan IV B-32/Centaur04/30/99 Delta III 259/Galaxy-X08/26/98 Delta III 269/Orion-305/04/99 Mars Climate Orbiter09/23/99 Mars Polar Lander12/03/99 STEX04/15/99 Argos02/20/99 PanAmSat Galaxy 405/19/98 Spike that occurred in cumulative hazard rate of space systems during was result of forgotten or ignored lessons learned
27 June WG List of Space Industry’s Top-10 Reliability Program Problems 1.Valuable RMA lessons learned often are not in a format that is readily assessable or useable by Reliability Program, or they have become “lessons lost” in an over-whelming mass of engineering information. For example, a useful lesson learned might never be linked to equipment that it applies if name that is used to search for information is different than name recorded in database. 2.Sometimes a Reliability Critical Item becomes (1) a “weakest link” because a design weaknesses was uncovered too late to implement a design change, or (2) an “unknown failure” because a critical failure mode was not identified, or (3) an “underestimated failure” because a failure cause or failure mechanism was unknown or not understood, or (4) an “escaped failure” because a fault slipped pass Test. 3.System reliability predictions often do not include probability of occurrence estimates for all relevant failure modes, failure mechanisms, and failure causes. For example, probability of induced faults during manufacture or probability of damage during assembly usually is not included in a reliability prediction.
27 June WG List of Space Industry’s Top-10 Reliability Program Problems (Cont.) 4.Sometimes, assumed adequacy of R&M requirements or accuracy of R&M predictions is not supported by input data. 5.Job openings for reliability analysts are steadily decreasing, and as a result, number of filled positions is insufficient to adequately support an increasing number of space system development projects. This situation is leading to reliability assessment methods being improperly applied, untimely, or not cost-effective. 6.Many commercial R&M assessment tools have major shortcomings that may not be obvious to casual users. For example, tools may have inaccurate models, unverifiable modeling parameters, high misapplication rates, etc. 7.Often, lack of design-relevant Technical Performance Measurements (TPMs) for R&M tasks leads to insufficient funding to perform tasks necessary for a High-Reliability Program. For example, a customer or manager might believe that High-Reliability can be tested-in more cost-effectively than it can be designed-in.
27 June WG List of Space Industry’s Top-10 Reliability Program Problems (Cont.) 8.Throughout space industry, identical R&M tasks are being called by different names and vise versa. Inconsistency among reliability practices has become a major problem since DoD canceled military standards in mid 90’s. 9.Some customers believe that all Reliability, Dependability, and Availability predictions for satellite constellations are too conservative. Basis of this belief is rooted in historical evidence that shows contingency procedures of ground operations are very effective for extending useful life of satellites far beyond their predicted mean-life. This phenomenon has resulted in many customers buying more satellites than necessary to meet mission requirements. 10.Often it is difficult for an organization to assure that latest versions of the R&M assessment models match latest configuration of space system design. Part of this problem is because reliability assessment tools generally do not label every element in the model with date and time it was created.
27 June Scope of Space Systems Dependability DTF Standard Scope of Dependability DTF standard covers: –Space Systems Engineering processes used for generating Dependability data –Extensible Markup Language (XML) definitions used for transferring Dependability data to and from a database Standard applies to both hardware and software Dependability data
27 June Purpose of Space Systems Dependability DTF Standard Purpose of Dependability DTF Standard is to: 1.Provide space systems producers with a High-Reliability Program model that is proven effective 2.Provide space systems producers with criteria for selecting appropriate R&M assessment tools 3.Provide space systems producers with a single model for building databases that are proven effective for achieving High-Reliability requirements for space systems 4.Provide space systems customers and producers with consistent criteria for measuring effectiveness of a High-Reliability Program 5.Provide tool developers with a common DTF for R&M assessment data
27 June Structure of Space Systems Dependability DTF Standard
27 June Dependability DTF Groups A - Requirements Models B - Functional Models C - Physical Models D - Stress Parameters Models E1 - Reliability Analysis Models E2 - FMECA Models F1 - Maintainability Analysis Models F2 - Failure Analysis Models G1 - Operational Dependability Analysis Models G2 - Operational Availability Analysis Models H1 - Dependability Design Concerns & Rules Models H2 - Sneak Design Clues Models
27 June General Format for Transferring Reliability Requirements Data RELREQ (Reliability Requirement Model) REQTYPE (Requirement Type) = SYSTEM or ALLOCATED REQSOURCE (Requirement Source) RELFUNC (Specified Reliability Value) = Real ENVIR (Specified Mission Environment) PROFILE (Specified Mission Profile) FAILDEF (Specified System Failure Definitions) VERIFY (Requirements Verification Methods)
27 June General Format for Transferring Mission Environment Data ENVIR (Mission Environment) EMODE (Environment Mode) = Operation, Storage, or Transport) TEMPRANGE (Temperature Range) = Real Range TPUNIT (Temperature Units) = Alphabetic (Celsius, Fahrenheit, Absolute) HUMRANGE (Humidity Range) = Real Range HUMUNIT (Humidity Units) = Alphabetic ALTRANGE (Altitude Range) = Real Range DUNIT (Distance Units) = (Kilometers, Miles, Feet) BPRANGE (Barometric Pressure Range) = Real Range PUNIT (Pressure Units) = Alphabetic (Inches HG, Atmospheres, PSI) MAXWIND (Maximum Wind Speed) = Real VUNIT (Velocity Units) = Alphabetic (MPH, KM per Second, etc.) RADIATION (Radiation) = Real
27 June General Format for Transferring Reliability Block Diagram Data RELBLOCK (Reliability Block Diagram Model) RELNAME (Reliability Block Diagram Model Name) = Alphanumeric OUTLINK (Model Output Link Name) = Alphanumeric INLINK (Model Input Link #1 Name) = Alphanumeric : RELCONFIG (RBD Math Model) = SERIES or PARALLEL or BINOMIAL or… RELBLOCK (Child Reliability Block Diagram Model) and/or RELFUNC (Reliability Function Model #1) = Real and/or RELDATA (Empirical, Analytical, or Simulation Data Table #1) = Real and/or RELSTATE (Reliability State Transition Diagram #1) = Real and/or : ENVIR (RBD Model Mission Environment) PROFILE (RBD Model Mission Profile) FAILDEF (RBD Model Failure Definition)
27 June Format for Transferring Weibull Function Probability Data RELFUNC (Weibull Function Probability) = Real WEIBULL RELNAME (Weibull Function Name) = Alphanumeric PREDTYPE (Prediction Type) = FIELD, TEST, PHYSICS, or HDBK SOURCE (Prediction Source) = Alphabetic SHAPE = Real SCALE = Real STARTTIME (Start Time) = Real ENDTIME (End Time) = Real TIMEUNITS (Time Units) = Alphabetic (Hours, Years, Days, etc.) LCONFIDENCE (Lower Confidence Bound) = Real or UNK or NA Legend: UNK means confidence bound is unknown NA means parameter values are based on assumptions
27 June Format for Transferring Exponential Function Probability Data RELFUNC (Exponential Function Probability) = Real EXPONENTIAL RELNAME (Exponential Function Name) = Alphanumeric PREDTYPE (Prediction Type) = FIELD, TEST, PHYSICS, or HDBK SOURCE (Prediction Source) = Alphabetic MTBF (Mean Time To/Between Failures) = Real STARTTIME (Start Time) = Real ENDTIME (End Time) = Real TIMEUNITS (Time Units) = Alphabetic (Hours, Years, Days, etc.) LCONFIDENCE (Lower Confidence Bound) = Real or UNK or NA Legend: UNK means confidence bound is unknown NA means MTBF value is based on assumption
27 June Format for Transferring Mean Failure Free Operating Period Data RELFUNC (Exponential Function Probability) = Real EXPONENTIAL RELNAME (Exponential Function Name) = Alphanumeric PREDTYPE (Prediction Type) = FIELD, TEST, PHYSICS, or HDBK SOURCE (Prediction Source) = Alphabetic MTBF (Mean Time To/Between Failures) = Real STARTTIME (Start Time) = Real ENDTIME (End Time) = Real TIMEUNITS (Time Units) = Alphabetic (Hours, Years, Days, etc.) LCONFIDENCE (Lower Confidence Bound) = Real or UNK or NA Legend: UNK means confidence bound is unknown NA means MTBF value is based on assumption
27 June Progress of WG to Date Completed survey identifying top-10 Reliability Program Problems Completed draft outline for standard Started drafting write-up for some sections in draft standard
27 June Conclusions New standard will: Provide space systems developers with a process for solving top-10 Reliability Program Problems Provide space systems producers with a High-Reliability Program model that is proven effective Provide space systems producers with criteria for selecting appropriate R&M assessment tools Provide space systems producers with a single model for building databases that are proven effective for achieving High-Reliability requirements for space systems Provide space systems customers and producers with consistent criteria for measuring effectiveness of a High- Reliability Program Provide tool developers with a common DTF for R&M assessment data