SolarArrayDriveBearinq Protection Floorflatness andbestpossible alignments wereevaluated bytheLMSSC stressengineer todetermine whatloadsmightbeimparted totheduplexbearings intheL7solararraydrive(SAD). Itwasfoundthat therewasareal(worstcase)possibility ofthebearings beingoverloaded. Toprevent thisfrom happening without making Herculean effortstolevelthedeployment floor,straingageswereinstalled on theyokeandcalibrated topermitadirectmeasurement oftheforcesgoingintotheSAD.(The interpretation ofthestraingaugereadings became averydifficult task,buteventually thestraindatawere successfully post-processed andfoundtobebelowthelimitloadsforyielding.) InitialSolarArrayTesting InitialBenchTesting Engineering benchtestsoftheRRSperformed in1997hadtwopurposes: calibrating thetorquerequired onthecabletensioning nuttoachieve propercablepreload, andselecting thepropersplitringwasher for theshockabsorber assembly. Antnstronmachine wasusedtodevelop therelationship between nut torqueandcabletension. Auniquetorquewasdeveloped foreachcable. Atestfixturewithagasactuated separation nutwasusedrepetitively instatistically meaningful teststo determine thepropersplitwasher needed todissipate the5.3kN(1200Ibf)preload thatwastobeapplied witheachcable.Thetestobjectives weremet,butthereweresomeinteresting andimportant detailsthat wereoverlooked. Noemphasis wasplacedondemonstrating 25mmorgreater travelofthereleased cable,andthesplitwasher wasnotadequately inspected afterthetest,whichwouldhaveshowed they wereyielding duetotheexcessive interference. Intheadaptation ofaheritage designtoL7,subtleyet criticaldetailsweremissed thatcouldhaveeasilybeendocumented ontheengineering drawings ofthe heritage design. Manual De_)loyments InOctober andNovember of1997,thesolararraywasdeployed manually priortoinstallation onthe spacecraft. Itwassoonrealized thattheslightslopesoftheuneven floorhadledtolateralforcesonce thearraywasdeployed outovertheflooronthelow-friction airpads.Thehand-held forcegauges were utilized onceagaintomeasure thelateralcomponent ofthedownslope force.Upto2N(0.44lbf)was measured insomeoftheworstlocations ontheepoxyfloor. Attheclosest-in hingeline,withamoment armofseveral arraypanellengths, andmultiple panels, the slope-induced torquewasanorderofmagnitude greater thantSetorques thetwohingesprings produced, drastically affecting thedeployment pathsofthepanelsandinvalidating measurements of deployment time.Infact,thepanelassembly clearlydeployed downhill intothelowspotsonthe deployment floor.Thecontours weremeasured andplottedtogainanunderstanding ofthedegree of unevenness ofthefloor.Anattempt atfillingthelowestspotsonthefloorwasmadeusingalowviscosity epoxy,butthelaborinvolved wasintense andlessthanasquaremeter(-i0sqft)wassotreated. Asthearraydeployed acrosstheflooronitsoriginal squareairpads,thecorners oftheairpadswould comeintocontact withthefloorastheytriedtospansmallfluctuations inthefloor'ssurface. Thiscaused theassembly tostoprepeatably invarious locations. Smoothing attheselocations wasattempted butit became obvious thatthiswouldnotbepractical acrosstheentirefloormeasuring 4.9m(16ft)wideby 9.1m(30ft)long.Whentheproblems withthesquarepadswereheardofbackatNASAGoddard Space FlightCenter, itwassuggested thatroundairpadsleftoverfromTRMMspacecraft's solararray deployment testingbeemployed. Theproperfittingadaptations wereimplemented bysWa|es Aerospace andtheroundairpadswereaddedtothesupport standsintimeforthenextdeployment test. Majorproblems Surface OnApril28,1998,thefirstpyrotechnically initiated deployment fromthespacecraft wasattempted. This majortestinvolved almosttheentireI&TteamatLMSSC andwasattended bynumerous managers. The spacecraft waspowered upandloadedwithflightsoftware. Special testequipment included theyoke 218