rayinspectionofallcartridgeweldmentswasconsidered inconclusive relativetoweldmentworkmanship,giventhatanyconclusionregardingtheintegrityoftheconvolutedbellows'insidediameterweldswouldbe speculative atbest.Standardleaktestswereperformedonthebellowsassemblies toverifyhermeticity, butaevaluation ofthebellows insidediameter welds,forameasurement ofsuchparameters asweld penetration, wasconsidered impractical. Further, standard leaktestevaluation ofthecartridge final closure weldswasalsoimpractical. Thefinalclosure weldswerevisually andX-rayinspected. Thesoft failureofadamping cartridge wasconsidered credible. Additionally, thisfailuremodewasconsidered to bearandom failure, ratherthanafailurecommon toalldamping cartridges implemented onSRTM Basedonthesoftfailuremodecoupled withaShuttle payload safetytwo-fault tolerance requirements, in thiscasetheconcern waschanges inthestructural dynamic whichcouldleadtoattitude controlinstability, thebending modedamping mechanism wasdesigned toincorporate threedamping cartridges. Gasbubble formation withinafluidfilleddamper isasignificant concern; thisconcern isfurther exacerbated inspaceapplications. Stewart, Powers, andLyons,1998,havediscussed anexample ofthis problem inregardtorotarydampers. Thisdegraded performance condition issimilartothesoftfailure mode.Effectively, thegasbubblecanactlikeaverysoftspringthatisinserieswiththedamping element. Thegasbubbleeffectcanbesosevere thatfromadynamic perspective adeadzone orbacklash is created withinthedamper whenagasbubble isformed withinthefluid.Theprimary protection against gasbubble formation withintheviscous fluidusedherewasavolumetric overfill, andtheuseofthe bellows asanaccumulator, suchthatpressure wasmaintained onthefluidoncethecartridge entered a vacuum environment. Theapproach takentowardtheoverpressurizing thefluidwastofillthedamper at atemperature belowthespecified operating temperature, inthiscasebelow-40°C.Thesilicone fluidhas apositive volumetric expansion coefficient relative totemperature, i.e.,asthefluid'stemperature increases itsvolume increases aswell.Further, inthedamping cartridge application considered herethe bellows wereusedasanaccumulator, thatisthebellows wereaflexible container whichcouldexpand andcontract withthefluid'svolumetric changes. Giventhatthebellows areelasticwithvolumetric spring stiffness, thenasthefluidexpands duetoatemperature increase, moderate fluidpressure increases are incurred duetothebellows accumulator effect.Finally, thermal control wasapplied tothedamping cartridges suchthatthenominal minimum expected operating temperature was-17°C(0°F).Giventhis minimum expected operating temperature, thefluidvolumetric expansion, andthebellows spring stiffness, theminimum expected fluidpressure wasdetermined tobeapproximately 103kPa(15psi). Thesilicone fluidwasdegassed priortocartridge filling.Unfortunately, thefluidwasonlyexposed toa vacuum ofapproximately 10.2Torr.Further, thefluidwasexposed totheambient atmosphere duringthe fillingprocess. Hence, thefluidwasnotconsidered completely degassed. Therefore, thepossibility of bubbleformation wasconsidered highlyunlikely, butcredible. Theissueofgasbubbleformation withinthe damping cartridge wasultimately resolved byrequiring asetofstructural dynamic identification testsbe performed duringthatSRTMon-orbit checkout phase. Thesuccess criteriaoftheidentification testswas structured suchthatifthemeasured structural dynamics matched preflight predictions thenthemission couldproceed toitsmapping phase,conversely ifthemeasurements didnotmatchthepredictions then changes wouldberequired totheattitude controldesignbeforemapping wasauthorized. The"stiff"failuremodegenerically described anyoftheconditions wherethedamping cartridge was seized, i.e.,itcouldnotbestroked. Theprimary concern herewasseizure ofthepistonrodinthelinear journal bearings, i.e.,thelabyrinth seals,dueparticulate contamination thatcouldcausethissinglesliding surface interface tojam.Themitigations employed toprotect against journal bearing seizure included silicone fluidfiltration priortothecartridge fillingprocess, cartridge component precision cleaning priorto assembly, andcartridge assembly inacontrolled cleanenvironment, i.e.,aflowbench. Giventhatthe SRTMdamping cartridges wereamodification ofaproven designthathadnotexhibited anyin-service seizure typefailures, thedesign heritage provided additional confidence thatthisdesign wasnot susceptible toseizure typefailures. Inanefforttominimize anyfrictionforceduetoincidental contact of thepistonrodwiththelabyrinth seals,tightconcentricity tolerances wereemployed onthecylinder, and labyrinth sealassemblies. Further, cross-blade flexures, i.e.,universal joints,wereemployed ateachend ofthecartridge suchthatendmoments, whichwouldbecreated duetovarious misalignments, wouldbe minimized. Fluidfreezing wasalsoclassified asastifffailure. Thistypeofstifffailurewasprotected against bythermally controlling thedamping cartridges suchthatthenominal minimum cartridge temperature was-17°C(0°F)versus thesilicone fluidfreezing temperature ofapproximately -70°C. Further theminimum cartridge operating temperature without thermal controlwas-35°C.Forthepurposes 90