kg/sec(1.0Ib/sec)flowingthrough thehydrostatic bearing. Atemperature sensormonitors testerinlet temperature andwhenitreaches aredline, thetestisautomatically terminated. Thisprevents gasfrom entering thetestrig,whichwouldbedetrimental tothebearings. Throughout thetests,sensors monitor temperatures, pressures, speeds, andloadsandarecapable ofstopping thetestwhenanyredlinevalue isreached. Afterthetestisover,personnel areallowed backintotheareatosecurethevalvesandcontrols. Ittakes approximately 18hoursforthetestrigto"thawout".Whentheicehascleared, aborescope inspection canbeperformed ofthebearings andinternal hardware. After15,000seconds havebeenaccumulated, thetestrigisremoved fromthestandandtakentoadisassembly roomforamidpointinspection. Ifthe hardware andbearings shownodegradation, thetesterisreassembled andtakenbackforfurthertesting. Attheendof31,000seconds, therigisremoved forfinaldisassembly andinspection. Results TestPro.qram Thistestseriesconsisted offifteenrotational attempts. Twelve testsweresuccessful inthat35,000rpm wasreached. Inoneattempt, facilityproblems aborted testing. Inanother, therotordidnotbreakaway andcomeuptospeed,andinthelastattempt, thespeedwasveryerraticandtherigwasshutdown manually. Speedfluctuations hadbeenseeninothertestaswell,butthetargetspeedwasreached. The erraticspeedwasattributed totherollersbecoming skewed inthebearing andactingaswedges that slowed orlockedtherotor.Aneffortwasmadetore-orient therollersbyraisingandlowering theshaftin thetestrigbutproblems stillpersisted onarandom basis.Thetesttimeintherigwas10,894seconds withatotaltimeatspeedincluding previous turbopump timeof15,975Seconds ontheballbearing and 12,635seconds ontherollerbearing. Thetesterwasremoved fromthestand(Figure 4)foraninspection ofthebearings tocheckfordamage. Bearing Inspections Thebearings werevisually inspected andexamined underamicroscope. Noobvious evidence wasseen forthelocking oftherotororspeedfluctuations. Somelightrubbing wasvisibleontheupstream facesof therollersandsomewearinthecagepockets hadoccurred duetotheradialloading. Surface metrology wasdoneontherollersandballs.Theareasthatwerehighlighted earlierwerere-examined for degradation. Theanalysis showed thatthemajorrivermarking didnotgrow,butsmaller "tributaries" branched outfromthemainfeatures. Figure5showsaballwithtwosurface features thatweremapped. Intheposttestpictures, thesmaller surface crackscanbeseenrunning fromthemainfeatures. Figure6isanother ballwithoneareathat waswatched. Thesamedegradation happens onthisball.Figure7isarollerwithsmallsurface distress features. Theposttestphotoshowsthatthesurface resisted cracking betterthantheballs.Theroller didshowsignsofparallel grooving, thought tobefromthefiberglass fibersintheArmalon TMcage pockets. Thisgrooving wasseenonseveral oftherollers. Figure8showsanother rollerwithsurface features. Theposttestphotograph showssomesmoothing ofthesurface anddebrisscoring. Ingeneral, alloftherollersresisted thesurface cracking betterthantheballs. Marshall SpaceFlightCenterhassomeofthebestsurface metrology equipment available. Two examples ofthisareFigure9and10.TheWYKONT2000 instrument canlookatsurfaces andprovide valuable information onallRq,Ra,Rt,Rp,andRvvalues. Athreedimensional mapcanbemadeofthe surface thatprovides depthsandwidthsofselected areas.Colorisusedtorepresent differing depths andheights offeatures. Figures 9and10areofthetwoballsinFigures 5and6.TheX(horizontal) and Y(vertical) profiles canbecompared alongwiththe3Dcolorplotsforbeforeandafterresults. TheXand Ycoordinates canbechanged foranoveralllookatthesurface. 335