MIL-HDBK-338B root cause analysis

NOTMEASUREMENTSENSITIVEMIL-HDBK-338B1October1998SUPERSEDINGMIL-HDBK-338A12October1988MILITARYHANDBOOKELECTRONICRELIABILITYDESIGNHANDBOOKThishandbookisforguidanceonly.DonotcitethisdocumentasarequirementAMSCN/AAREARELIDISTRIBUTIONSTATEMENTA.Approvedforpublicrelease;distributionisunlimited.Downloadedfrom:35.Downloadedfrom:35.MIL-HDBK-338BFOREWORDiFOREWORD1.ThishandbookisapprovedforusebyallDepartmentsandAgenciesoftheDepartmentofDefense(DoD).ItwasdevelopedbytheDoDwiththeassistanceofthemilitarydepartments,federalagencies,andindustryandreplacesinitsentiretyMIL-HDBK-338A.Thehandbookiswrittenforreliabilitymanagersandengineersandprovidesguidanceindevelopingandimplementingasoundreliabilityprogramforalltypesofproducts.2.ThisHandbookisforguidanceonly.ThisHandbookcannotbecitedasarequirement.Ifitis,thecontractordoesnothavetocomply.3.Reliabilityisadisciplinethatcontinuestoincreaseinimportanceassystemsbecomemorecomplex,supportcostsincrease,anddefensebudgetsdecrease.Reliabilityhasbeenarecognizedperformancefactorforatleast50years.DuringWorldWarII,theV-1missileteam,ledbyDr.WernhervonBraun,developedwhatwasprobablythefirstreliabilitymodel.ThemodelwasbasedonatheoryadvancedbyEricPieruschkathatiftheprobabilityofsurvivalofanelementis1/x,thentheprobabilitythatasetofnidenticalelementswillsurviveis(1/x)n.TheformuladerivedfromthistheoryissometimescalledLusser’slaw(RobertLusserisconsideredapioneerofreliability)butismorefrequentlyknownastheformulaforthereliabilityofaseriessystem:Rs=R1xR2x..xRn.4.Despitethelonggestationperiodforreliability,achievingthehighlevelsneededinmilitarysystemsistoooftenanelusivegoal.Systemcomplexity,competingperformancerequirements,therushtoincorporatepromisingbutimmaturetechnologies,andthepressuresofacquisitionbudgetandschedulecontributetothiselusiveness.Inthecommercialsector,highlevelsofreliabilityarealsonecessary.Recently,Americanproductsonceshunnedinfavorofforeignalternativeshavemadeoraremakingacomeback.ThisshiftinconsumerpreferencesisdirectlyattributabletosignificantimprovementsinthereliabilityandqualityoftheAmericanproducts.5.Notingtheseimprovements,andfacingashrinkingdefensebudget,theDepartmentofDefensebegantheprocessofchangingitsacquisitionpoliciestobuymorecommercialoff-the-shelfproductsandtousecommercialspecificationsandstandards.Theobjectiveistocapitalizeonthe“bestpractices”thatAmericanbusinesshasdevelopedoradopted,primarilyinresponsetoforeigncompetitivepressures.Whencombinedwiththeknowledgeandexpertiseofmilitarycontractorsinbuildingcomplexandeffectivemilitarysystems(soundlydemonstratedduringtheconflictwithIraq),itishopedthatthesecommercialpracticeswillallowtheDepartmentofDefensetoacquireworld-classsystemsontimeandwithinbudget.Downloadedfrom:35.MIL-HDBK-338BFOREWORDii6.TheinformationinthisHandbookreflectsthemovewithinthemilitarytoincorporatebestcommercialpracticesandthelessonslearnedovermanyyearsofacquiringweaponsystems“bythebook”.Militaryaswellascommercialstandardsandhandbooksarecitedforreferencebecausetheyarefamiliartobothmilitaryandcommercialcompanies.Manyofthemilitarydocumentsarebeingrescinded,socopiesmaybedifficulttoobtain.Forthosewhohavecopiesorcanobtainthem,themilitarydocumentsprovideawealthofvaluableinformation.7.Beneficialcomments(recommendations,additions,deletions)andanypertinentdatawhichmaybeusefulinimprovingthisdocumentshouldbeaddressedto:AirForceResearchLaboratory/IFTB,525BrooksRoad,Rome,NY13441-4505.Commentsshouldbesubmittedusingtheself-addressedStandardizationDocumentImprovementProposal(DDForm1426)appearingattheendofthisdocumentorbyletter.Downloadedfrom:35.MIL-HDBK-338BTABLEOFCONTENTSiiiTABLEOFCONTENTSSectionPage1.0SCOPE.......................................................................................................................1-11.1Introduction................................................................................................................1-11.2Application.................................................................................................................1-11.3Organization...............................................................................................................1-12.0REFERENCEDDOCUMENTS................................................................................2-12.1GovernmentDocuments............................................................................................2-12.1.1Specifications,StandardsandHandbooks.................................................2-12.2OtherReferencedDocuments....................................................................................2-33.0DEFINITIONSOFTERMSANDACRONYMSANDABBREVIATIONS..........3-13.1Introduction...............................................................................................................3-13.2Definitions........................................................................................