Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 1Jacek S. Stecki
Risk assessment in aerospace systems
Jacek S. SteckiPHM Technology/Monash University
Melbourne, Australia
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 2Jacek S. Stecki
Key issues – Risk drivers
Supportability:– Reduction of life-cycle cost– Safety – environmental, personnel– Reliability – hardware, functional
Reduced manning levelsNeed to reduce the volume of scheduled maintenanceSecondary effects of failuresInherent design problemsNeed to reduce spare parts inventoryHigh performance requirementsAvailability of specialised personnelInsurance and classificationCriticality of the equipment to productivity/availabilityCost of lost production or lost availability as a result of equipment failureCost of fixing a problem in terms of repair and bringing the machine back to a serviceable conditionEtc.
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 3Jacek S. Stecki
Integrated Logistics Support
Integrated logistics support (ILS) is an integrated approach to the management of logistic disciplines in the military
The pupose of ILS is to ensure that the supportability of the system is considered during its design and development in order:
To create systems that last longer and require less supportTo reduce costsTo increase return on investmentsTo assure supportability throught the operational life of the system
The impact of ILS is measured in metrics: Reliability - Availability - Maintainability (RAM) Reliability - Availability - Maintainability - Testability (RAMT) Reliability - Availability - Maintainability - System safety (RAMS).
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 4Jacek S. Stecki
Integrated Logistics Support
Integrated Logistics
Reliab ility, M ain ta in ab ility and M ainten ance) P lan ning
Supply (Sp are p art) S upp ort acqu ire resources
Su pport and T est Equ ipmen t/Eq uipm ent
M anpower and Personn el T raining and T rain ing Support
Tech nical Data / Pu b lications
Computer Resources Sup port
Facilities Packag in g , Handlin g , Storage, and T ransportation
Design In terface
UK Def ence S tandard (DEFST AN) 00-600
Supportability of the System
Assuring continued operation and functioning of the systems
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 5Jacek S. Stecki
Performance-based Logistics (PBL) is an outcome-based, performance-oriented product support strategy
A product support provider (PSP) or product support integrator (PSI) is contracted to meet performance metric (s) for a system or product
The purpose of PBL:
increased system availability, reliabilityshorter maintenance cycles, and/or reduced costs
Thus PBL fits well with ILS
----------------------------------In U.S. Department of Defense (DoD) acquisition programs, the PBL approach is mandated as a first-choice strategy.
– A PBL contract was awarded to Alstom for delivery of trains in France– Also called Performance-based-Contracts
Performance-based Logistics
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 6Jacek S. Stecki
Reliability - Availability – Maintainability (RAM)
The ability of an item to perform a required function under given conditions for a given time intervalIt is generally assumed that the item is in a state to perform this required function at the beginning of the time intervalGenerally, reliability performance is quantified using appropriate measures. In some applications these measures include an expression of reliability performance as a probability, which is also called reliability.
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 7Jacek S. Stecki
Risk reduction – CBM/PHM
What is it?Risk assessment using techniques like FMECA, HAZOP, RCM etc.Diagnostics – is the process of determining the state of a component to perform its function(s)Prognostics – is predictive diagnostics which includes determining the remaining life or time span of proper operation of a componentHealth Management – is the capability to make appropriate decisions about maintenance actions based on diagnostics/prognostics information, available resources and operational demand.
D e s ig nRisk
Sensors
Diagnostic FDI
Prognostics
Failures Identification
Criticality Assessment
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 8Jacek S. Stecki
PHM - Fusion of the technologies
Sensors Artificial intelligence Neural
nets, fuzzy logic, genetic algorithms
Algorithms (vibration etc.) Communication capabilities Interchange of maintenance
data Integration of data Security of data User friendly interface Autonomy to be provided by
software agents (Jack platform from AOS)
PrognosisPrognosisLayerLayer
Prognostics and Health
ManagementPHM
MaintenanceMaintenanceaware Designaware Design
SensorsSensorsLayerLayer
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 9Jacek S. Stecki
Goals of PHM
Enhance Mission Reliability and Equipment Safety Reduce Maintenance Manpower, Spares, and Repair Costs Eliminate Scheduled Inspections Maximize Lead Time For Maintenance and Parts Procurement Automatically Isolate Faults Provide Real Time Notification of an Upcoming Maintenance Event at all
Levels of the Logistics Chain Catch Potentially Catastrophic Failures Before They Occur Detect Incipient Faults and Monitor Until Just Prior to Failure
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 10Jacek S. Stecki
PHM Paradigm (Joint Strike Fighter F35)
PHM Paradigm
Sensor based Proactive
Prognostic capability
Intelligent Sensors
Data Fusion
Virtual Sensing Model-based Prognostics
Maintenance aware Design
Co-current with Design
Optimization
Life Cycle
Autonomous
Open Architecture
Reliable and Robust
Model-based Prognostics
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 11Jacek S. Stecki
Joint Strike Fighter F35 PHM Setup
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 12Jacek S. Stecki
Aerospace
RisksSevere operating environmentStringent statutory safety standardsSafety critical systemsExpensive MaintenanceLong innovation lead time High technologyConservative attitudesHigh reliability requirementsSingle shot operationsVery high cost of failureTools to deal with risks
Computer based design methodsReliability and Hazard AnalysisFailure analysis (FMECA/FTA)PHM (Prognostics and Health Management) Condition Monitoring - CBMTesting
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 13Jacek S. Stecki
CBM/PHM - what are we dealing with?
FMECA Production Losses
Reliab
ility
Condition monitoring
Prognostics
Maintenance
DetectionDiagnosis
Algorit
hms
Failure modes
Faults
Simulation
Downtime
TestingRisk M
inimiza
tion
$$$$$$$!Training
Fall-back AnalysisHazards
Safety
Training
FMECAStandards
TrainingFMECA
Reliab
ility
Diagnosis
Sensor fusion
Failure modes
BITTraining
FMECA
Fault Tree
ROI
FMECA
Reliab
ility
SensorsDiagnosis
Education
Failure modes
Training
Training
FMECA
Functional
AnalysisTraining
Education
Sensor fusionSensor fusion
Artific
ial
intell
igenc
eMaintainabil
ity
Availa
bili
ty
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 14Jacek S. Stecki
Reasons for failure of Risk Assessment
Dependencies of failures not identified – spreadsheet vs model basedInadequate Identification of Risks - functional failures (failure modes) vs physical failures Incomplete database of failures (deficient FMECA)Taxonomy – confusion what is the cause, mechanism of failure, fault, symptom and/or failure modeSensor fusion not based on failures dependencies (fall-back – testability) Diagnostic rules not based on dependenciesReliability of Hardware not the same as Functional ReliabilityDifferent models for Criticality and Reliability Assessment
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 15Jacek S. Stecki
Risk reduction or is it?
Risk is still there if failures are missedWe cannot design a diagnostic system without knowledge of failuresWe do not really know what we should monitorSensors cover only identified failures
D e s ig nRisk
Sensors
Diagnostic FDI
Prognostics
Failures Identification
Criticality Assessment
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 16Jacek S. Stecki
Barriers
The Advanced Technology Program (ATP), of the National Institute of Standards and Technology (NIST), held a workshop on Condition-Based Maintenance (CBM) as part of it's November 17-18, 1998 Fall Meeting in Atlanta.
Discussions with companies identified 3 technical barriers to CBM's widespread implementation: The inability to accurately and reliably predict the remaining useful
life of a machine ( prognostics) The inability to continually monitor a machine (sensing) The inability of maintenance systems to learn and identify impending
failures and recommend what action should be taken (reasoning).
These barriers could potentially be addressed through innovations in three technical areas: Prognostication capabilities Cost effective sensor and monitoring systems Reasoning or expert systems
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 17Jacek S. Stecki
Risk Assessment FMECA
Failure Modes
Effects
Criticality Analysis
What effect does the failure have ?
Criticality Analysis of failure
Possible Failures FMFMECAECA
FMFMEECCAA
FMEFMECACA
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 18Jacek S. Stecki
acceptable operating range
Component model
FMEA model
EnergyEnergy
apply forceControlparameterse.g. pressure
Noisee.g.. friction
Measuredvariablee.g.. force
ComponentFunction Definition
High range
Low range
Effect 1 downstream,e.g.. damaged support
Upper limit
Lower limitEffect 2 downstreame.g. failed to lift
PhysicalComponente.g. actuator
Failure Modes and Effects
Failure Modes and Effects
Component model
Tribological model
WearFriction
Failure Modes and Effects
LoadVelocityetc.
ComponentRepresentation e.g. drawing
Modeling Failure
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 19Jacek S. Stecki
Modelling of failure
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 20Jacek S. Stecki
Fault
Fault
Fault
All faults are enumerated.Transient and steady-state responses to faults are identified
Fault propagation - dependability
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 21Jacek S. Stecki
PHM Cycle
PHM requires two main cycles of development, design and operation
The Design Cycle is required in order to generate the knowledge base from which the PHM system can obtain its decisions.
The Operation Cycle describes the steps taken within the PHM system from detection of faults through to conveying instructions or actions.
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 22Jacek S. Stecki
Interaction between MAD and CBM/PHM Layers at Design Stage
System Concept
System specification
Implementation
Functional diagram
FASTContraints
RiskLayer
PHM Layer
Sensor set
DiagnosticsOptimization
Life cycle
FMECA/HAZOP
Prognostics
Sensors
Techniques
Faults
Techniques
Functions
Manufacturing
PH M L a y e r
M A DL a y e r
D e s ig n p r o c e s s
MAD – Maintenance aware Design
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 23Jacek S. Stecki
Criteria for RCM Processes
SAE JA1011 “Evaluation Criteria for RCM Processes” defines seven questions for RCM:
What are the functions…of the asset…(functions)? In what ways can it fail…(functional failures)? What causes each functional failure (failure modes)? What happens when each failure occurs (failure effects)? In what way does each failure matter (failure consequences)? What should be done…(proactive tasks and intervals)? What should be done if a suitable proactive task cannot be
found?
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 24Jacek S. Stecki
MADe software
Fa ilure databa se
Fa ilures de pen dabili ty
B IT des ig n & evaluat ion
Auto Sen sor s elect ion
Fa ilure diagram s
Te stabilit y
Fa ilures critica li ty
Cau ses Fa ilureM ec hanism s
Fa ults Fa ilure m ode s
Fa ilure ta xonom y
Com p one nt
Sys te m s
Parts
Fa ilure diagram s
Fu nct io nal fa ilure diag ra ms
Auto func tiona l an alysis
Auto qu alitat ive s im ulat ion
Auto report ge nerat io n
Auto de s ign ofdiag nos tic ru le s
Fa ilure coverageas ses sm ent
Failure database
Sensor selection/coverage
Coverage of am b ig uity
Dat ab ase
FM EA/FM ECA
Use d e fine d se nsors
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 25Jacek S. Stecki
RR250 Engine Lubrication System
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 26Jacek S. Stecki
Jet Engine Lubrication System Model
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 27Jacek S. Stecki
Model of pump
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 28Jacek S. Stecki
Define Component Structure
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 29Jacek S. Stecki
Define Component Functions
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 30Jacek S. Stecki
Define Physical Failures
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 31Jacek S. Stecki
Propagate Functional Failures >> Dependency
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 32Jacek S. Stecki
Assess Criticality
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 33Jacek S. Stecki
Produce FMEA/FMECA Report
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 34Jacek S. Stecki
Assess hardware Reliability
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 35Jacek S. Stecki
Fault Tree
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 36Jacek S. Stecki
Define Sensors Locations
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 37Jacek S. Stecki
Select sensors and generate diagnostic rules
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 38Jacek S. Stecki
CAD concurrent with MADe
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 39Jacek S. Stecki
PHM Design Cycle Deliverables
At the end of the risk assessment process, the user has knowledge of:How the system can fail (failure modes)How critical each failure isWhat are the causes of functional failures What are the interactions between functional failuresWhat physical failures are linked to functional failureWhere to place sensors – i.e sensor fusingHow to monitor physical failures How to diagnose functional failureWhat is the expected reliability of the sensing systemWhat is the expected functional and hardware reliability of the system
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 40Jacek S. Stecki
Despite expectations the acceptance and effectiveness CBM is in question. To be effective:CBM/PHM programs must be designed and executed with the knowledge of the risks to which a system is exposed, i.e. the knowledge how the system failsModel-based failure analysis, defining failures dependencies and improving completeness of risk identifications, should be adopted in preference to spreadsheet and “spreadsheet” like FMECA methodologyModel-based failure analysis should be adopted to enhance knowledge retention, knowledge transfer and to facilitate integration of risk assessment through supply chainsTaxonomies of functions, failure concepts, components should be adopted to improve readability/portability of risk assessment resultsDiagnostic rules and Sensors sets should be selected on the basis of dependencies between failure modes (symptoms >>> syndrome)Clear hierarchy of failure concepts (cause> failure mechanism> fault> failure mode) should be enforced in risk assessment processPhysical failures (cause/failure mechanism/fault) and their symptoms should form basis for BIT design
Concluding Remarks
Conference AERONET "Aviation Valley" , 13-14 2011
PHM Technology Pty Ltd 41Jacek S. Stecki
Thank You!
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