CAST Analysis of the Internaonal Space Staon EVA 23 Suit...

CASTAnalysisoftheInterna3onalSpaceSta3onEVA23SuitWaterIntrusionMishap

STAMPWorkshop2018

AkshayKothakondaMassachuseDsIns3tuteofTechnology March28,2018

Background and Events Leading up to EVA 23 EV1(ChrisCassidy)hadcompletedfiveEVA’s,totalingalmost30hoursandEV2(LucaParmitano)hadcompletedoneEVA,las3ng6hours

EVA23Crew

DuringEVA21onMay12,2013,thesuitthatleakedwasusedwithoutanyissuesEVA21

•  EVA22onJuly9,2013hadthesamecrewandsuitsasonEVA23•  ½to1literofwaterwasfoundinEV2’shelmetpostEVA•  EV1reportednotseeinganywaterinEV2’shelmetduringairlockrepressandEV2waslookingdownandleaningforwardduringthis3me

•  Basedonthis,thecrewincorrectlyconcludedthewaterenteredthehelmetduringrepressasEV2pressedthedrinkbagwithhischestandpinchedbitevalveopenwithhischin

•  Thegroundteamacceptedthistheoryandtherewasnofurtherinves<ga<on•  TherewasnodiscussionofwaterleakageduringEVA23pre-briefs

EVA22

Events During EVA 23

•  Roughly38minutesintotheEVA23(July16,2013),Parmitanohada“CO2SensorBad”alarm•  Another6minuteslater,hereportedfeelingwateronthebackofheadandneck•  Thewaterwasreportedtoincreaseoverthenext10minutes•  Cassidyvisuallyconfirmedthepoolingofwater•  Thesourceofthewaterwasnotiden<fiedbytheEVAcreworthegroundandtheEVAcrewcon3nuedtowork

•  ThegroundeventuallycalledforanEVATermina<on23minutesaEerParmitanofirstreportedwater

•  Duringtransla3onbacktoairlock,watermigratedtofrontoftheface,coveringhiseyes,nose,andears;andsoakinghiscommunica3onscap

•  Thiscausedseverevisibility,breathing,andcommunica<onissues•  AZerrepress,thesuitwasdoffedexpedi3ouslyand1to1.5litersofwaterwasfound

EVA23

NASA Investigation •  Ini3altroubleshoo3ngwasperformedbytheflightcrew•  TheISSProgramconvenedaMishapInves3ga3onBoard(MIB)toinves3gatethisHighVisibilityCloseCall(HVCC)

•  EventandCausalFactorTree(ECFT)wasdevelopedwhichiden3fiedproximate,intermediate,androotcauses,andcontribu3ngfactors

•  Severalobserva<onsweremadethroughcourseofinves3ga3onthatcouldimproveISSopera3ons

•  Recommenda<onsweredrawnfromthesetasks•  HumanfactorsanalysisperformedusingDoDHumanFactorsAnalysisandClassifica3onSystem(HFACS)

•  MishapwasfoundtobeduetoinorganicmaterialsblockingthedrumholesintheEMUwaterseparator,resul3nginwaterspillingintotheventloop

•  Sourceofinorganicmaterialshasnotbeenfound•  MIBreportandthisstudyfocusonwhywaterintrusionaEerEVA22wasnotinves<gatedandwhyEVA23wasnotimmediatelyterminated

Why do a CAST Analysis?

•  EnablesonetobePerdissectthecomplexinterconnectedorganiza<onalandreal<meflightopera<onsstructureoftheISSProgram

•  Thisgivesamorerealis<candtransparentpictureofwhythisincidentoccurred•  Itallowsforgenera3onofamorecomprehensivelistofrecommenda<ons•  Overall,itoffersaclearerunderstandingofthemishap•  Providesanopportunitytocomparetheresultsofaneventbasedapproachwithasystemstheorybasedone

Extravehicular Mobility Unit

Safety Control Structure

PhysicalSafetyControls

•  Filterimpuri3esinEMU•  Keepwaterfromgebngintoventloop

ConstraintsViolated

•  CO2Sensor•  EMUHelmetPurgeValveSafetyEquipment

•  Inadequatefiltra3onofimpuri3es•  Fan-Pump-Separatorfailureduetoimpuri3es

Failure/InadequateControls

•  EMUini3allycer3fiedforsingleShuDlemission,isnowcer3fiedforsixyearsonboardISS

•  ErroneousCO2sensorreadingnormalizedover3me

PhysicalContextualFactors

EVACrewmembers

•  DiagnoseEMUproblems•  Makejudgementcalltoabort/terminate

SafetyResponsibili3es

•  Trainingdidnotcoverwaterinhelmet• WaterintrusionaZerEVA22notinves3gatedContext

•  Didnotcommunicatewatertemperature•  Didnotrequesttermina3onimmediately

UnsafeDecisions/ControlAc3ons

•  Crewinfluencedbydrinkbagleakagetheory•  Concurredwithground’srecommenda3ontocon3nuewithEVA

ProcessModelFlaws

MissionControlCenter

•  DiagnoseproblemsduringEVAopera3onsandinves3gatepost-EVA

•  Constantlyrefreshtrainingandsystemknowledge


•  Underextreme3mepressurestoprepareforEVA23aZerEVA22

• Waterinhelmetnormalizedandtrainingdidnotcoverthis•  Thereweremul3plesimultaneouscommunica3onloops

Context

•  Didnotinves3gatewaterleakaZerEVA22•  DidnotterminateEVA23assoonaswaterwasreported


•  Therewasanunsubstan3atedpercep3onthatdrinkbagsleak•  Therewasafeelingthatinves3ga3onintoEVA22waterleakwouldbe3meconsuming

ProcessModelFlaws

MissionOpera3onsDirectorate

•  Createopera3onalprocedures•  Trainandprovidesimula3onstoFlightControl


•  Consequencesofwaterleakagewasnotunderstoodandnormalized

•  Simula3onsexpectedfindingsolu3onsinsteadoftermina3ngContext

•  Failuremodeofwaterleakagenotcoveredinflightrulesandtraining

• MODEVALessonsLearnedArchivelacksdescrip3onsoffailurespriortoSTS-88


ProcessModelFlaws

EVAOffice

•  Iden3fyhazardsandprovideQAinEMUandEVA•  Integratesafetyac3onswithrestofISS


•  Groundtes3ngofbehaviorofwaterinEMUwaslesssevere•  ISSProgramhadnorequirementtoreviewEMUFMEA/CIL•  ADri3oninsuitexper3se

Context

•  DidnotunderstandseverityofwaterinEMU•  UpdatestoFMEA/CILnotcomprehensive• WaterinhelmetandCO2sensorerrorsnormalized


•  Basedongroundtests,waterinEMUwasdeemedtonotbeahazard

ProcessModelFlaws

ISSProgram

•  EnsureallISSsystemshavecompletedSMAprocesses•  ChairingISSSafetyReviewPanel


•  BudgetcutsaffectedplannedreviewofEMUFMEA/CIL•  SMAprocessforEVAseparatefromrestofISSandismanagedbyEVAOffice

Context

•  Emphasizedmaximizingcrew3meformissionoversafetytasks•  DidnotrequireperiodicreviewofEMUFMEA/CIL•  NorequirementforEVA/EMUtrainingofMERSafetyTeam


•  Upda3ngFMEA/CILwasthoughtofasmerepaperworkanddidnotreceivetheaDen3onwarranted

ProcessModelFlaws

Recommendations • MODtodevelopflightrulesforwaterintrusionandtrainaccordingly.Thisincludesinves3ga3nghelmetpurgevalveopera3onandreviewinganddetailingproceduresthatrequirecrewtocontactground

• MODshouldtrainFCTandEVAcrewinpriorEMUfailuresincludingusingsimula3ons

• MODshouldtrainMERSafetyTeaminEVAsystemsandbemadearequirementbyISSProgram

•  Simula3onsshouldallowforFCTtoterminate/abortanEVA• MODshouldimplementchannelstoallowlowerlevelflightcontrolelementstohaveamoredirectaccesstoFlightControlRoomandFlightDirector

•  FlightSafetyOfficeshouldenforcebestprac3cestoaddressknownfailuremodesandnormalizeddevia3onswithinMODSMAprogram

Recommendations (continued) • Possibilityofasphyxia3onshouldbeincludedinFMEA/CILbyEVAOfficeandenforcedbyISSProgram

•  ISSProgramalongwithMODandEVAOfficeshouldreviewcaseswheredevia3onsarenormalized(forinstancepresenceofsmallamountsofwaterinhelmetcausingfogging)andaddressthem.ThisshouldbedoneforwiderISSProgram.OtherexamplesincludeCO2sensorandsublimatorinefficiency.

•  ISSProgramalongwithMODandEVAOfficeshouldreviewandupdateFMEA/CILandaddressfailures.WithresourcesfromISSProgram,EVAOfficeshouldupdateandreleaseEMUlessonslearned,systemdevelopment,designandflightprocedurera3onales.Thesemaybeincludedintrainingprograms.

•  ISSProgramshouldhavebeDeroversightoverFCTinrepor3nganomalies•  ISSProgramshouldencouragecultureofpriori3zingastronautsafetyandofanyonebeingabletovoicesafetyconcernstohighermanagement

Recommendation (continued) •  ISSProgramshouldreviewimplica3onsofchangingwaterqualityandchemistryonISSsystems

•  ISSProgramshouldreviewacceptabilityofEMU’ssixyearcer3fica3on•  ISSProgramshouldrequireperiodicreviewofFMEA/CILofISSsystems

Conclusion

• CASTprovidedahighlysystema<canalysisprocessforaverycomplexsocio-technicalsystem

•  Thisresultedinahighlyefficientprocess• Morenumberofsignificantsafetyrecommenda<onsweregeneratedusingCASTthanthatusingevent-basedapproach

References

• NASAMishapInves/ga/onReport:ISSEVASuitWaterIntrusionHighVisibilityCloseCall,IRISCaseNumber:S-2013-199-00005

• Hansen,C.,Cassidy,C.(2014)MishapInves/ga/onBoardSummaryofExtravehicularAc/vity23:LessonsLearnedFromaSpacewalkCloseCall.JournalofSpaceSafetyEngineering,Vol.1,pages32-39

• Kothakonda,A.(2015).DesignofSensorSystemtoDetectPresenceofAnomalousWaterinAirLinesintheExtravehicularMobilityUnit.JournalofSpaceSafetyEngineering,2(2),74-78.

BACKUP SLIDES

EVA Communication Paths

Water Separator Spinning Drum and Pitot Components

ECFT Proximate Causes

CAST Analysis of the Internaonal Space Staon EVA 23 Suit...

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