-53.9°C(-65°F)operation orcolder. Allprecautions weretakentominimize ESDsusceptibility, including theincorporation ofsoftEMIgaskets atthesidecoverinterfaces. Thebrushless motorwasdesigned and builtbyMoogInc.andhada51mm(2.0in)ODby~15mm (.6in)stacklength. Themotoriscapable of providing morethan3timestherequired torque, butiscurrent clipped bythecontroller electronics at about1.5timestherequired torque. Manual Override capability issupplied intheeventofapowerfailureviaadualinput,10-mm(3/8in), recesssquare drives. Thedualinputallowsequaloperation fromtwoopposite sidesoftheBMA,meeting therequirement ofasingleunittofitintooneoffourpossible positions atthefinallevelassembly in different orientations. ThebasicMOinputof50rpmandupto30.5N-m(270in°lb)oftorquesupplythe samefunctionality attheBMAoutputasthepowered maindrivesystem. Theeffective gearratioofthe MOmechanism is12.17:1. TheMOutilized auniquewormdrivearrangement tobeabletofunction even withthemotorthrough thethirdstagegearsetjammed, andtomeettheoverallpackage sizeconstraints. Whilethemaindrive isrunning, theMOdriveisheldstationary viaa"no-back-drive" device. Similarly, whiletheMOruns,themaindrivemustremainstationary fromthethirdstageplanetary output(fourth stagesungear)tothefirststageinput(motorshaft).Therewasinsufficient cogging torqueinthebase motordesigntoguarantee norotation wouldbeallowed duringMOoperation. Thisdeficiency was overcome byaddingapassive magnetic "cogging" unitontothetopofthemotor. Thecogging unit supplies -170mN°m(24in°oz)oftorquestatically, whileonlyrequiring 40mAofdrivingforce(orloss) duringmotoroperation. Summary ofLessons Learned Though theoriginally proposed concept utilized designheritage gathered fromMoog's program, several itemsusedintheBMAdesignwouldrequire verification through development testbeforeenough confidence couldbegainedtogotoQualification (Qual). Someitemsrequired neworuniquedesigns and/ornewmaterial combinations thathadnotpreviously beenusedbyanymanufacturer. Thebleeding edgebecame thecuttingedgethrough thelessons learned aspresented inthispaper. Theseincluded thefollowing items: Packaae Size Thedesignrequirement contained arigidspecification forpackage size.Theactuator wasrequired tofit intoanexisting C-channel trussstructure, andthesameactuator needed tofitfourdifferent locations. Thisconstraint provedtobethemajordesigndriver. Inordertoobtainthespecified speedandtorque outputwithinthepowerrequirements, allavailable volume wasutilized. Everyitembelowwasneeded to maketheoveralldesignwork,pushing thelimitsofcurrent technology. Thepackage weightwassetat 4.5kg(10.0Ib)max,witha4.2kg(9.3Ib)actual. Theunitfinaldesigncontained 1020individual and over300uniqueparts. Pyrowear ®2675GearMaterial Originally, 440CandA286wereselected asthegearmaterials fortheBMA."Standard" commercial or military gradegearmaterials lackedtherequired corrosion resistance tomeetspace-level requirements. Platingorothersurface protection couldhavebeenaddedtothestandard materials tohelpthemmeet thecorrosion resistance, butnocombination foundcouldhandlethedesigncontact stress. Duringthe designphase,itwasdetermined thatthetwoselected materials mayhavegallingproblems, lackedthe strength toobtainneeded margins (inthecaseofA286),orweretoobrittle(inthecaseoffullhard440C) tosurvive therequirements. Arelatively newmaterial hadrecently beenintroduced byCarpenter Technologies thatcouldanswer alltheseissues. Thematerial wasacasehardenable stainless steel calledPyrowear _675.Ithadsimilarcorrosion resistance to440Candanswered thedesignstrength, durability andcorrosion issues. Theonlyproblem withthematerial wastherewaslittletonoinformation onheattreatment toobtaintheneeded 0.1to0.2mm(0.004to0.008inch)effective casedepth.Also,all 76