Preliminary Test&Evaluation Sincetheunproven linkage design wasbeingfabricated fromrelatively costlymaterials requiring a longer procurement cycleandconsiderable machining timeduetothematerial toughness, the decision wasmadetodevelop anEngineering TestUnit(ETU)usingreadily available, easily machinable materials. TheETU(Figures 4,5&6)provided manybenefits: 1.Development andverification ofcomponent fabrication programs usinglesscostlymaterials 2.Design verification toolforform,fitandassembly techniques 3.Lowlevelfunctional testingoflinkage assembly viamanually releasable separation bolt 4.Increased confidence levelindesign TheETUassembled easily,requiring noadditional procedures orprocesses. Whenassembled afew design improvements became apparent, Mostnotably, bythreading theboltcutterclampscrew access holeintwoofthelinks,setscrews couldbeinstalled afterassembly toeliminate thefree movement theboltcutterassembly, whichwasaconcern underlaunch vibration conditions. When assembled usingamanually releasable separation bolt,functional testswithuptoa10%separation boltpreload couldberepeatedly conducted, filmedatnormal andhighspeedandreviewed without theexpense andavailability ofusingpyrotechnically actuated boltcutters. Numerous testswere performed andinallcasesthemechanism actuated nominally. AsafinaltestoftheETU,the opportunity became available toperform asingletestwiththefull8896-N (2000-1b) separation bolt preload andrecorditusinghigh-speed digitalvideo. Withtheincreased levelofconfidence inthelinkage design provided bytheETUandtesting, materials wereordered andfabrication oftheprotoflight unitauthorized. Protoflight Test&Evaluation Aswaslearned during theinvestigation intotheonflightanomaly, viewing theplayback ofthe assembly's actuation recorded onhighspeed videoproved tobetheonlyacceptable method of verifying thatMaBIL mettherequirements. Fortheprotoflight functional testing theopportunity became available tousehigh-speed digitalvideoasopposed tohigh-speed filmcameras used during theprevious investigation. Thedigitalvideo,whilenothaving theresolution ofthefilm cameras, provided otheradvantages. Before performing atest,thesetupcouldbeverified tobe functioning properly, andfollowing atest,therecording wasavailable forimmediate playback without havingthedelayduetofilmprocessing. Theimmediate playback feature provided theabilitytotweak orchange thesetupbasedonwhatwasviewed intheprevious test.Theoverall testtimewasalso reduced improving costandschedule. TheHHMarman BandInterconnect Linkage TestProcedure, SSPP, 870-PROC-587, wasdeveloped tospecify thetestarticleconfiguration, functional tests, thermal testsandvibration testsrequired fortheflightqualification ofthe.MaBIL. Functional Test Thefunctional testsconsisted ofassembling theprotoflight unitstothePESinafullflight configuration (Figures 7)andtakinghighspeedvideoat1000frames persecond fromthetopand sideofboththenominal dualpyrotechnic boltcutterandsingleboltcutterfirings. Thevideos were thenreviewed ataplayback rateof1framepersecond todetermine iftherequirements weremet. Realtimeobservations ofeachtestgavetheindication thatthelinkage controlled themotion ofthe actuating mechanism asexpected. Review ofthevideoplayback confirmed thatineachcasethe MaBILperformed asdesigned, permitting themarman bandtorelease independent oftheboltcutter (mass), whilethesupported boltcutterwasmoved radially awayfromtheseparation plane. Then, oncethebandexpanded totheendoftravel, theboltcutterremained inthe"locked out" configuration (Figures 5&7),allowing minimal rebound ofonlythemarman clamps. Thepulldown springs effectively pulled theassembly belowtheseparation planeandtorestonthestops. Incidental contact waslimitedtocontact between themarman clampshoesandtheejection system support basewithsaidcontact occurring belowtheseparation plane.Based ontheseobservations theMaBILwasdetermined tohavemetthefunctional design requirements andcouldbesubjected toenvironmental testing. Thermal Testing Thethermal testingconsisted ofsubjecting thetestarticletoonethermal cycle,fromthehotcaseat +70°Ctothecoldcaseat-50°C,withafour-hour soakperiodateachextreme. Thenbacktoeach temperature extreme forafinalfour-hour soakandmechanism demonstration. Themechanism demonstration consisted ofaworstcasesinglecutterfiringandonlyvisualobservation sincethe 270