British Airways Flight 5390 - AviationChief.Com

​British Airways Flight 5390 · The bolts engage with 10 UNF Kaylock floating anchor nuts mounted on the inside of the windscreen frame. · The left windscreen had ... Home LearntoFly PPL InstrumentRating CPL MultiEngineRating ATPL RuleofThumbs ALittleDeep Downloads > Forms Regulations Miscelaneous PilotPsychology AccidentReports News Blog WriteforUs Gallery AboutUs ContactUs ​BritishAirwaysFlight5390 Mechanicsarejustaslikelyaspilotstobecome complacent astheygrowwithexperienceandearntherespectoftheirpeers.Infact,inmanywaystheyareatgreaterrisk.Theyarenotsubectedtothesameregimenoftrainingandevaluation;theycangolongerwithouta"coursecorrection"tobringthembackintothestandardstheywereinitiallytrainedto.Mechanicscanoftenbereliedupontoworkalone,eveninlargeshops,andtheymayfindthemselvesinspectingtheirownwork.Insomecases,thefirsttestofamechanic'sworkisthenexttimetheairplaneflieswithaloadofpassengers.Thisisacasestudyofjustsuchamechanic.ThemechanicinquestionexhibitedallfouraspectsofwhatIcall"MaintenanceMalpractice."Hetookseveralshortcuts,bypassedthechanceforasecondsetofeyestoperformqualityassurance,mayhavenotbeenrecentlytrainedtorelearnlessonshehadforgotten,andhewasn'tproperlyrested.Heisveryluckynobodydied.Sothisisaflightmishapbutwewon'tbediscussingtheflightotherthantosaythepilot'swindshieldblewoutpassing17,300'becauseitwasinstalledimproperly.Thecaptainwasblownmostlyoutofthecockpitandwouldhavediedhadn'titbeenfortheeffortsofthecabincrewholdingontohimandofthefirstofficerforgettingtheairplaneonthegroundquickly.Wepilotscanlearnfromthisexercise,however.Lookyourairplanesovercarefullyaftermaintenance.Ifyouhaveaonemechanicshop,developaraportandvolunteertobethatsecondsetofeyes.Thelifethiseffortsavescouldbeyours. AccidentReport Date:10June1990Time:7:33Type:BACOne-Eleven528FLOperator:BritishAirwaysRegistration:G-BJRTFatalities:0of6crew,0of81passengersAircraftFate:RepairedPhase:EnrouteAirport:(Departure)BirminghamInternationalAirport(BHX/EGBB),UnitedKingdomAirport:(Destination)MalagaAirport(AGP/LEMG),Spain Narrative​TheFlight Theaccidentoccurredduringascheduledflight(BA5390)fromBirminghamtoMalaga,Spain.With81passengers,fourcabincrewandtwoflightcrewtheaircrafttookofffromBirminghamInternationalAirportat0720hrsand,havingbeentransferredbyATCtotheDaventryandthentheBristolSectorControllerofLondonAirTrafficControlCentre(LATCC),wasclearedtoFlightLevel(FL)140.Anumberofradarheadingswereordereduntiltheflightwasinstructedtomaintainaradarheadingof195°MandclearedforafurtherclimbtoFL230.Theco-pilothadbeenthehandlingpilotduringthetake-offand,onceestablishedintheclimb,thecommanderwashandlingtheaircraftinaccordancewiththeoperator'snormaloperatingprocedures.Atthisstagebothpilotshadreleasedtheirshoulderharness,usingthereleasebaronthebuckle,andthecommanderhadloosenedhislap-strap.At0733hrsasthecabinstaffpreparedtoserveamealanddrinks,and,astheaircraftwasclimbingthroughabout17,300feetpressurealtitude,therewasaloudbangandthefuselagefilledwithcondensationmist.Itwasatonceapparenttothecabincrewthatanexplosivedecompressionhadoccurred.Thecommanderhadbeenpartiallysuckedoutofhiswindscreenapertureandtheflightdeckdoorhadbeenblownontotheflightdeckwhereitlayacrosstheradioandnavigationconsole.TheNo3steward,whohadbeenworkingonthecabinsideofthedoor,rushedontotheflightdeckandgraspedthecommanderroundhiswaisttoholdontohim.Thepursermeanwhileremovedthedebrisofthedoorandstoweditintheforwardtoilet.Theothertwocabinstaffinstructedthepassengerstofastentheirseatbelts,reassuredthemandtookuptheiremergencypositions.Theco-pilotimmediatelyattemptedtocontroltheaircraftand,oncehehadregainedcontrol,initiatedarapiddescenttoFL11O.Here-engagedtheautopilotwhichhadbecomedisconnectedbydisplacementofthecontrolcolumnduringthecommander'spartialegressandmadeadistresscallonthefrequencyinusebuthewasunabletohearitsacknowledgmentduetothenoiseofrushingairontheflightdeck.Therewassomedelayinestablishingtwo-waycommunicationsandconsequentlytheBristolSectorControllerwasnotimmediatelyawareofthenatureoftheemergency.ThisledindirectlytotheLATCCWatchSupervisornotadvisingtheaircraftoperatoroftheincident,asrequiredbytheManualofAirTrafficServices(MATS)part1.ConsequentlytheinitiationoftheBritishAirwaysEmergencyProcedureInformationCentreplanwasdelayed.Meanwhilethepurserre-enteredtheflightdeckand,havinghookedhisarmthroughtheseatbeltsofthefourthcrewmemberjumpseatwhichwaslocatedbehindtheleft-handpilot'sseat,wasabletoassisttheNo3stewardintherestraintofthecommander.Thetwomentriedtopullthecommanderbackwithintheaircraftand,althoughtheycouldseehisheadandtorsothroughtheleftDirectVision(DV)window,theeffectoftheslipstreamfrustratedtheirefforts.TheNo2stewardenteredtheflightdeckandhewasabletorelievetheNo3stewardwhosearmswerelosingtheirstrengthastheysufferedfromfrostbiteandbruisingfromthewindscreenframe.TheNo2stewardgraspedthecommander'srightleg,whichwasstuckbetweenthecockpitcoamingandthecontrolcolumnwhilsthisleftlegwaswedgedagainsthisseatcushion.Thestewardthenstrappedhimselfintotheleftjumpseatandwasabletograspbothofthecommander'slegsbutnotbeforehehadmovedafurther6to8inchesoutofthewindowframe.Heheldhimbytheanklesuntilaftertheaircrafthadlanded.Theco-pilothadrequestedradarvectorstothenearestairportandhadbeenturnedtowardsSouthamptonAirportandeventuallytransferredtotheirapproachfrequency.Havingverifiedthattherewassufficientrunwaylengthavailableforalanding,theco-pilotmanoeuvredtheaircraftontoavisualfinalapproachtorunway02andcompletedasuccessfullandingandstopontherunwayat0755hrs.TheengineswereshutdownbuttheAuxiliaryPowerUnit,whichtheco-pilothadstartedupduringthedescent,wasleftrunningtoprovideelectricalpowertocertainaircraftsystems.Assoonastheaircraftcametoahalt,passengersweredisembarkedfromthefrontandrearairstairswhiletheairportandlocalfireservicesrecoveredthecommanderbackintotheaircraftfromhispositionhalfoutofthewindscreenframe,wherehehadremainedthroughoutthedescentandlanding.HewastakentoSouthamptonGeneralHospitalsufferingfrombonefracturesinhisrightarmandwrist,abrokenleftthumb,bruising,frostbiteandshock.Theothercrewmembersandpassengersweremedicallyexaminedbutapartfromonestewardwhohadcutsandbruisingtohisarmtherewerenootherinjuries.TheWindshieldReplacementTheBACOne-Eleven500seriesisatwin-engined,passengeraircraftpoweredbyRollsRoyceSpeyturbofans.Thefuselageispressurisedandair-conditioned;8,000feetconditionsbeingobtainableat35,000feet,underwhichconditionsthepressuredifferentialis7.5psi.Thepilots'windscreensareoffive-plyglass/polyvinyl-butylconstruction,theinnermost(glass)laminatebeinglow-temperedtoformasplintershieldintheeventofabirdstrike.Windscreenheatingisapplied,primarilytoimprovetheimpactresistanceofthewindscreenatlowoutsideairtemperatures.Thewindscreenisnotdesignedonthe'plug'principal,wherecabinpressureeffectivelycontributestoholdingitinplace,butisfittedfromtheoutsideoftheaircraftandissecuredbymeansof90countersunkbolts,alsofittedfromtheoutside.Thelargenumberofboltsarerequiredtopreventleakageofpressurisedairthroughthewindowsealbuttheforceofinternalairpressurecouldbesatisfactorilyresistedbyfarfewerbolts.​ThewindscreenwasfoundnearCholsey,Oxfordshire,alongwiththewindscreenoutboardcornerpostfairingstripandsomeassociatedbolts.Ofthe90boltsusedtoattachthewindscreentotheaircraft,11hadremainedinthewindscreenand18werefoundloosenearby;onehadremainedintheaircraftwindowframe.Twenty-sixoftheboltsrecoveredwiththewindscreenwerenewboltsidentifiedagainsttheBritishStandardashavingthepartnumberA211-8C.Theremainingfourboltsrecoveredwerere-usedboltsidentifiedashavingthepartnumberA211-7D.TheillustratedPartsCatalogue(IPC)specifiesthattheattachingboltsshouldbepartnumberA211-8D.Thespecificationsfortheseboltsare: ​Theboltsengagewith10UNFKaylockfloatinganchornutsmountedontheinsideofthewindscreenframe.Thereplacementwindscreenhadbeeninstalledwith84bolts(A211-8C)whosediameterswereapproximately0.026ofaninchbelowthediametersofthespecifiedboltsbutofthesamethreadpitch,andsixbolts(A211-7D)whichwereofthecorrectdiameter,but0.1ofaninchtooshort.Theleftwindscreenhadbeenchangedduringthenightshiftofthe8/9thJune1990andtheaccidentflightwasthefirstsincethatinstallation.Eightyoftheboltswhichhadattachedtheoldwindscreenwererecoveredfromtheworkareaduringtheinvestigation,and78ofthesewereidentifiedasA211-7D,theremainingtwobeingA211-8D. Theoldwindscreen,whichhadbeenfittedfouryearsearlier,beforetheaircrafthadbeenacquiredbyBritishAirways,hadthereforebeenprimarilyattachedbyboltswhichwere0.1ofaninchshorterthanthosespecified.Ofcoursethisbegsthequestion:howwasthemechanicabletosatisfactorilytorquedownscrewswiththewrongdiameterandthreadcourseness?DuringthecourseoftheinvestigationBritishAirwayscarriedoutasimulationofthewindowfittingproceduretodeterminethetorquethatcouldbeappliedto8UNCcountersunkheadboltsfittinginto10UNFKaylocktypeanchornuts.Thecombinedresultsusing8UNCboltsin10UNFKaylocknutsshowedamaximumtorqueof12lbfinandanaverageof4.7lbfinatthreadslip.Examinationofthetorquelimitingscrewdriverusedtofitthewindscreen.Testsonasimilartorquelimitingscrewdrivertothatusedtofitthewindscreenshowedthatatalowsetting(5lbfin)thefeelofthescrewdriverclutchslippingwasindistinguishablefromthefeelofan8UNCthreadslippingina10UNFanchornut.Theresidualtorquewasconfirmedasbeinghighatavalueofapproximately30percentofthetorqueset,ratherthantheusualvalueofbetween5and10percent.Subsequentdiscussionswiththemanufacturerdisclosedthatthespecificationforthegrease,usedintheassemblyofthetorquelimitingscrewdriver,hadbeenchangedapproximatelyfiveyearsagobecauseofproblemsofthegreasebreakingdownwithage.Atthistimeretrospectiveactionforthosetorquedriversalreadysoldwasconsideredimpracticalbecauseofthelargenumbersinvolvedandthelackofinformationabouttheirlocation.Thescrewdriverundertestwasatleastfiveyearsoldandstripexaminationrevealedthattheexcessivefrictionwascausedbydeteriorationoftheoldspecificationgrease.Nosignificantwearwasevidentonthecamortheballbearings,andwhenrebuiltwiththecorrectgreasethetorquelimitingscrewdriverperformedsatisfactorily.Itissurprisingthat,giventhisknowledge,theentiresetoftorquescrewdriverswasn'tinspectedbecauseitwas"impractical."BeforethediameterofthereplacementboltshadbeenestablishedBritishAirwaysissuedaninstructiontobecarriedoutonallitsBACOne-Elevensbeforethenextflight,toremoveeveryfourthboltfromtheNo1left-handandNo1right-handwindscreenstocheckforcorrectlength.ThroughouttheBritishAirwaysfleetofBACOne-Elevenstwoaircraftfailedthecheck,havingatotalof41shortbolts(A211-7Ds).Thereportdidnotinvestigatethepossibilitythatthoseaircraftwindshieldswerealsoreplacedbythesamemechanic.Couldthecomplacencybehindtheseinstallationsbeisolatedtoonemechanicorisitmorewidespread?Indeed,couldthepreviousinstallationoftheaccidentaircraftalsobeentheworkofthesamemechanic?AsimilarcheckwascarriedoutonthefourBACOne-Elevensbelongingtoanotherairlineandtwoaircraftfailedthecheck,havingatotalof107shortbolts.TheShiftMaintenanceManagerglancedbrieflyattheMaintenanceManualashehadnotchangedawindscreenforabouttwoyearsandwantedtorefreshhismemory.Thischeckconfmnedhisimpressionthatitwasastraightforwardjobwithnoapparentdifficulties.TheIPC[IllustratedPartsCatalogue]wasavailableonamicrofichereader,butwasnotusedtoidentifythepartnumberoftheboltstobereplaced,consequentlyastockcheck,usingTIME[TotalInventoryManagementforEngineers],toassesstheavailabilityandlocationofreplacementboltswasnotcarriedout. TheShiftMaintenanceManagerjustifiedthisomissionbysayingthathewasquitesatisfiedthattheboltsthathehadremovedwerethecorrectbolts,andthatitwouldtakesomuchtimetofindthecorrectnumbersintheIPCthathedidnotfeeljustifiedinusingtheIPCinthecircumstancesofthejobinquestion.ThepageoftheIPCforthe528seriesaircraftshowsasketchofthepilot'sNo1windscreenandtheadjacentDV[DirectVision]window,butonlyillustratesonebolt-thatintheDVwindow,whichisanA211-7D.Thecomponentsforthepilot'sNo1windowarelistedinthetext,alongwithseveralalternativemodificationstates,anditsboltsaredefinedas'attachingparts'andareidentifiedasA211-8Ds.TheIPCforthe510series,incontrast,isveryclearinidentifyingthecorrectbolts.Theboltsactuallyfittedtothedefectivewindscreenwere,inthemain,A211-7Ds,theboltsillustratedasapplicabletotheDVwindow.Thatisboltsofthecorrectdiameterbut0.1ofaninchshorterthanthosespecified.TheShiftMaintenanceManagerremovedthewindscreenwiththeaidoftheAvionicsSupervisor,whoalsodisconnectedtheelectricalconnectorsofthescreenheaters.Theboltswere'oncondition'items,andassomeofthepaint-filledboltheadshadbeendamagedduringremoval,andothersshowedsignsofcorrosion,theShiftMaintenanceManagerdecidedtoreplacethemandtookoneoftheboltstothestoretoidentifyitbycomparisonwiththoseheldinthecarousel.Thecarouselswereunderthecontrolofastoremanandhaddrawerswhichwereclearlylabelledwithalocationcodetowhichengineersweredirected,afterenteringthepartnumberintotheadjacentstorescomputerterminal.Becauseoftheirsmallheadsizetheboltsdonotcarryindividualidentification,buttheShiftMaintenanceManageraccuratelymatchedtheremovedboltbygoingthroughseveraltrays,andcomparingtheremovedboltwiththedrawercontents.HethenidentifiedthepartnumberoftheboltasA211-7Dbylookingatthestoresissuenoteinthedrawer(thewindscreenshouldhavebeenfittedusingA211-8Ds). TheStoresSupervisor,whohadbeeninthejobforabout16years,informedhimthatA211-8Dswereusedtofitthatwindscreen,butdidnotpressthepoint. TheShiftMaintenanceManagerdecidedthatasA211-7Dboltshadcomeout,hewouldreplacethemwithboltsofthesamesize.TheminimumstocklevelinthecarouselforA211-7Dboltswas50,buttherewereonlyfourorfiveboltsinthedrawer(whencheckedbytheAAIBthefollowingMondayitcontainedfour).TheShiftMaintenanceManagerdrovetotheunsupervisedcarouselunderneaththeInternationalPier,takingtheremovedboltwithhim.Thedrawersinthiscarouselwerelabelledwiththepartnumberofthecontents,althoughthelabelswereoldandfaded.TheambientilluminationinthisareawaspoorandtheShiftMaintenanceManagerhadtointerposehimselfbetweenthecarouselandthelightsourcetogainaccesstotherelevantcarouseldrawers.Hedidnotusethedrawerlabels,eventhoughhenowknewthepartnumberoftheremovedbolt,butidentifiedwhathethoughtwereidenticalboltsbyplacingtheboltstogetherandcomparingthem.HealsopickedupsixA211-9Ds,thinkingthattheattachmentoftheoutboardcomerpostfairingstripwouldneedlongerbolts.Theaircraftmanualcallsforatorqueof15lbfintobeappliedtothebolts,whicharethenretorquedto5lbfinafter100flyinghours.TheShiftMaintenanceManager'sexperiencetoldhimthatmanyoftheboltswouldbefounduptothreeturnslooseduringtheretorqueprocedure,sohedecidedtoincreasetheinitialtorqueto20lbfin.TheBritishAirwaystoolstoreatBirminghamheldacalibrateddialindicatingtorquewrenchtocovertherangeof5to120lbfin,buttheretorquerequirementof5lbfinwasatthebottomoftherangeandthedialindicatingtorquewrenchwasnotconsideredsuitableforthistask.TwocalibratedtorquecheckinggaugeswereavailableatBirminghamtoallowengineerstoconfrrmthewrenchaccuracy.Thecalibrateddial-indicatingtorquewrenchwasnotavailableonthetoolboardthatnight,buttheStoresSupervisorhadrecentlyacquiredfromBritishAirwaysatLondon,onhisowninitiative,atorquelimitingscrewdriverspecificallyforthewindscreentask,butonreceiptitwasfoundtobeoutofcalibrationdateanditwasthereforenotclearedforuse.ItwasnotthecompanypolicyatBirminghamtoallowtheengineerstoadjusttorquewrenchesasandwhenrequired,butrathertohavethewrenchesadjustedinastandardsroomandthenissuedforuseatthatspecificsetting.ItwasthereforetheintentionoftheStoresSupervisortohaveitsetintheLondonstandardsroombeforeissue,but,intheabsenceofanysuitablealternative,thestoremansetthisscrewdrivertothefigureof20lbfinrequestedandgaveittotheShiftMaintenanceManager,whocheckedthesettingusingbothtorquecheckinggauges.HefittedthewindscreenusingS4oftheboltscollectedfromtheInternationalPiercarouselandobtainedasimilarfeelfromthetorquelimitingscrewdriverforeachone;afeelthatmethisexpectations.WhenhecametotheoutboardcomerpostfairingstripherealisedthattheA211-9Dboltsweretoolong,descendedfromthestagingandretrievedandrefittedthesixoldboltsthathehadremovedwiththefairing.ThenewboltsthathehadfittedwereinfactA211-8Cbolts-onesizedownindiameterbutwiththesamethreadpitchasthosespecifiedandwithin0.050ofaninchinlengthtotheA211-7Dboltsremovedfromthewindow.Theboltsengagein10UNF'Kaylock'floatinganchornuts;theselflockingactionistheresultofpartofthenutbeinganellipticalshapepriortotheinsertionofthebolt.Someoftheanchornutswereattacheddirectlytotheinsideoftheaircraftwindowframeandsomewerecarriedonstrips,themselvesattachedtothewindowframe.TheoutboardcornerpostfairingstripinterposedanadditionalthicknessandrequiredA2l1-8Dbolts,andthesewerespecifiedfortheattachmentofthewholewindscreen,eventhoughinthemajorityoflocationsapproximatelyfivethreadswouldbevisiblebelowananchornutfasteneddirectlytotheframewhenusedwithanA211-8Dbolt.Theamountofthreadinsafetywouldbereducedwhenusedwiththebackingstripsandtheoutboardcomerpostfairing.Thenumberofthreadsleftoverhadbeenconsideredinthedesignofthewindowassembly;itisnotuptothemechaniconscenetodecideheorsheknowsbetter.If,forexample,thismechanichadsuccessfullyinstalledthelongerboltsforthecorners,itcouldbethatduringpressurizationtheexpansionofothercomponentscouldinterferewiththesebolts.The"shadetree"mechaniconscenedoesn'tknowandwouldbewelladvisedtosticktothemanual.ThesafetyraiserusedbytheShiftMaintenanceManagerdidnotgiveeasyaccessacrosstothecentrelineoftheaircraft,andhehadtostretchovertheaircraftnosetoaccomplishthetask.DuetotheinadequateaccesstothejobandtheobscuringeffectofhislefthandtheShiftMaintenanceManagerwasnotinapositiontoobservethattheboltthreadwasslippingintheanchornutthread,insteadofthetorquelimitingscrewdriverallowingitsshafttoremainstationarywhilethehandlerotated.However,thebitandsocketwouldhavecontinuedtorotateinhislefthand.Thewindowwasfmishedinprimerandhadcountersunkholesforthebolts;anA211-8Cboltheadsitssignificantlyfurtherbelowthesurfaceofthewindow,downinthecountersink,thandoesanA211-7Dbolthead,leavinganannulusofunfilledcountersinkwhichiseasilydiscernablewhenviewedundergoodconditions.This'excessiveannulus'ofunfilledcountersinkwasnotseenWhentheboltswerebeingfittedtothewindscreencentrecolumn,theboltsfromtherighthandwindow,theheadsofwhichfilledthecountersinks,wereclosetothoseofthelefthandwindow,and,althoughpainted,thedifferenceisperceptibleundernormalcircumstances.TheShiftMaintenanceManagermissedthisdifferenceindepthoftheboltheadsinthewindscreencentrecolumn.Whenfittingtheoutsidecomerpostfairingwiththesixboltspreviouslyremovedfromit,theShiftMaintenanceManagerfailedtonoticethedifferenceintorqueachievedorthedifferenceincountersink:fitoftheboltheadsbetweentheoldandnewbolts.ThefollowingnighttheShiftMaintenanceManagercarriedoutanotherwindscreenchange,thistimearighthandone.ThejobhadbeensetupbeforehearrivedandhenoticedthattheboltswereA211-8Ds.HerecalledfittingA211-7Dboltsthepreviousnight,butherationalisedthattheaircraftwereoldandofdifferingmodificationstatesandthepreviousnighthehadanaircraftmodificationstandardrequiringA211-7DboltsandthatnighthehadanaircraftrequiringA211-8Dbolts.TheShiftMaintenanceManagersdidnotcriticisetheshiftsystem,howeverthepotentialproblemsassociatedwithsleepdeprivationandcircadianeffectswereacknowledgedandvariousstrategieswerecitedtocopewiththesituation.DuringtheinitialpartoftheinvestigationtheShiftMaintenanceManagerwhocarriedoutthewindscreenfitdidnotappeartograspthelackofcarethathisactionsimplied.Heco-operatedfullyintheinvestigationand,whenshownthefulllistoferrorsandomissionsthathehadmade,offeredanexplanationforeachindividualaction.ThepersonwhofittedthewindscreenwasaShiftMaintenanceManagerholdingauthorisationsonBACOne-Eleven,Boeing737,Boeing757,HS748andwithtransitauthorisationsonL-1011Tristar,Boeing747andaCAAlicenceholderforairframeandenginesontheViscount.Hisexperienceincluded10yearsintheRAF,followedby23yearswithBritishAirways.Heappearedtobeamature,dedicatedengineerwhowaswellrespectedbyflightcrewandengineersalike.HehadbeenonleaveovertheperiodofthelastnightshiftcarriedoutbyhisshiftandsotheFriday/Saturdaynightshiftduringwhichthewindscreenwasfittedwashisfirstnightworkforapproximatelyfiveweeks.Hehadhadanormalnightssleepthepreviousnightandhadgonetobedatabout1730hrs,andhadsleptfor1-1/2hours,gettingupat2030hrs.Hesaidthathewouldhavebeenhappierifhehadsleptforanhourlonger,butwasn'tdismayedthathehadnot.Hehadbeenina"daycycle"forfiveweeksandforhisfirstnightshiftheonlyhad1-1/2hourssleep. Analysis Iwouldcharacterizethemechanic'sactionsasoneofsomeonewhothinksheissmarterthanthepeoplewhodesignedtheairplaneanddoesn'tneedtoadheretostrictprocedureasaresult.Heassumesthatmatchingthenewboltstotheoldisgoodenough.Hebelievesalongerboltisneededforthecornersbutisunconcernedwhenhediscoverstheboltsheusedareshorterthanthoseforthenextwindshieldchange.Hedismissestheadviceofthepartssupplierwhosaysanotherboltiscalledfor.Hedecidesisowntorqueprocedure(20lbfinsteadof15lbf)isbetterthanthemanual's.Anumberofprocedureswereignoredandsomepoortradepracticesfollowed:TheIPC,availabletoidentifytherequiredbolts'partnumberwasnotusedThestoresTIMEsystem,availabletoidentifythestocklevelandlocationoftherequiredbolts,wasnotusedPhysicalmatchingofoldandnewboltsbytouchandeyewasattempted,leadingtoamismatchwithboltsfromtheInternationalPiercarouselArbitrarychoiceofA211-9DstofitthroughthecornerfairingtookplaceAnincreaseinbolttorqueoverthatstatedintheMaintenanceManualwasused.NonconformitywithBritishAirwaysstandardswasalsodemonstrated:AnuncontrolledtorquelimitingscrewdriverwassetupoutsidetheCalibrationRoom.DuringthecourseofhisdutiestheShiftMaintenanceManagerreviewedtheworkofhisshift,thisreviewaugmentedtheselfcertificationtaskrequiredoftheengineersbyBritishAirways'maintenancepolicy.Oncehehaddecidedtocarryoutrectificationworkhimself,hewithdrewfromtheactivesupervisionoftherestoftheshift.Thetaskofthewindscreeninstallationwasnotdesignateda'VitalPoint'andconsequentlynoduplicateinspectionwascalledforandnonetookplace,norwastheworkoftheShiftMaintenanceManagersubjecttoreviewbyanothermanager.ThustheShiftMaintenanceManagerhadnobackstopwithanychanceofdetectinghiserrors.Errorsthatweremademorelikelybythesleepdeprivationandcircadianeffectsassociatedwiththeendofafirstnightshift.Theadoptionofselfcertificationsystemswithinmanufacturingindustryhastypicallyresultedinsavings,mainlyarisingthroughreductioninscrapandintheachievementofhighermanufacturingefficiency.Nevertheless,attheendoftheproductionlinetheproductisnormallystilltested,beforebeingdespatched.Someaircraftmaintenancetaskswhichmaybeundertakenusingselfcertificationproceduresdonotallowforthetestingoftheendproductbeforeitisflown.ManyoftheactionstakenthatnightbytheShiftMaintenanceManagermaybedescribedasevidenceofalackofsufficientcareintheexecutionofhisresponsibilities.Suchacatalogueofeventsdoesnotequatetoamomentarylapseinbehaviourbutismoreindicativeoftheapproachofaconscientiousandpragmaticengineerworkinginannon-proceduralmanner.Suchadescriptionoftheindividualisnotnecessarilyinconsistentwithhis'exemplaryrecord',becauseuntilmatchedwithatasksuchasthiswindscreenchange,hisapproachwascapableofgoingundetectedbyanythingotherthanacloseobservationofhisworkpractices.Thenumberoferrorsperpetratedonthenightofthisjobcameaboutbecauseprocedureswereabused,'short-cuts'employedandmandatoryinstructionsignored.Evenwhendoubtexistedaboutthecorrectsizeofbolttouse,theauthoritativedocumentswerenotconsulted.AftertheeventtheShiftMaintenanceManagerconcerneddemonstratedalackofappreciationofthesignificanceoffailuretoadheretothespecifiedprocedures,goodtradepracticesandeventherequirementsoftheMaintenanceManual.Thereisclearevidenceofadifferentphilosophyappliedtopilots,whoarerequiredtoundergoregularlineandbasestandardisationchecks,andengineerswhoarenotsubjectedtoanycomparablestandardisationorrefresherchecks. ProbableCause Asafetycriticaltask,notidentifiedasa'VitalPoint',wasundertakenbyoneindividualwhoalsocarriedtotalresponsibilityforthequalityachievedandtheinstallationwasnottesteduntiltheaircraftwasairborneonapassengercarryingflight.TheShiftMaintenanceManager'spotentialtoachievequalityinthewindscreenfittingprocesswaserodedbyhisinadequatecare,poortradepractices,failuretoadheretocompanystandardsanduseofunsuitableequipment,whichwerejudgedsymptomaticofalongertermfailurebyhimtoobservethepromulgatedprocedures.TheBritishAirwayslocalmanagement,ProductSamplesandQualityAuditshadnotdetectedtheexistenceofinadequatestandardsemployedbytheShiftMaintenanceManagerbecausetheydidnotmonitordirectlytheworkingpracticesofShiftMaintenanceManagers. FinalAccidentReport Home LearntoFly PPL InstrumentRating CPL MultiEngineRating ATPL RuleofThumbs ALittleDeep Downloads > Forms Regulations Miscelaneous PilotPsychology AccidentReports News Blog WriteforUs Gallery AboutUs ContactUs