SRB CRITICAL ITEMS LIST PART NO.: A FM CODE: A04. ITEM CODE: REVISION: Basic. NO. REQUIRED: 8 (4 per actuator) DATE: March 1, 2002

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1 SRB CRITICAL ITEMS LIST SUBSYSTEM: ITEM NAME: THRUST VECTOR CONTROL Servvalve Assembly, Part f Servactuatr PART NO.: A FM CODE: A04 ITEM CODE: REVISION: Basic CRITICALITY CATEGORY: 1R REACTION TIME: Secnds NO. REQUIRED: 8 (4 per actuatr) DATE: March 1, 2002 CRITICAL PHASES: Bst SUPERCEDES: March 31, 1999 FMEA PAGE NO.: A-196 ANALYST: K. Schreder/S. Finnegan SHEET 1 OF 7 APPROVED: S. Parvathaneni FAILURE MODE AND CAUSES: Lss f utput frm three r fur servvalves caused by: CN 044 Bth nzzles r drain rifices clgged by cntaminatin Cil r electrical filter is pen r shrted Damaged electrical cnnectr Clgged fluid filter FAILURE EFFECT SUMMARY: Lss f three r fur servvalves leading t inadequate cntrl r t the actuatr ging hardver. Lss f Thrust Vectr Cntrl will lead t vehicle breakup and lss f missin and crew. Three success paths remain after the first failure. REDUNDANCY SCREENS AND MEASUREMENTS: Pass - ATP is cnducted n all units, redundancy is verified during ATP. Pass - Abnrmal utputs are detectable frm delta pressure measure-ments B58P1311A thrugh B58P1318A, by actuatr psitin mea-surements B58H1150C and B58H1151C, and by islatin valvecmmand measurements V79X5100X, V79X5101X, V79X5105X,V79X5106X, V79X5110X, V79X5111X, V79X5115X and V795116X. Fail - Fluid cntaminatin

2 FM Cde: A04 Date: March 1, 2002 RATIONALE FOR RETENTION: A. DESIGN The Servvalve Assembly is designed and qualified in accrdance with the end item specificatin 10SPC Material selectin is in cmpliance with MSFC-SPEC-522A. All servvalve piece-parts, subassemblies and assemblies are cleaned and assembly peratins are perfrmed in a cntrlled envirnment cnfrming t Class 100,000 clean rm cnditins. The Mg clean rm is certified per Mg QAP (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) The servvalve first stage rifices are prtected by a 20 micrn, 35 micrn abslute filter. Further cntaminatin prtectin is prvided by the 5 micrn abslute system filter and the servvalve inlet filter (10 micrn nminal, 15 micrn abslute). (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) The servvalve inlet filer is designed fr a twenty missin service life. (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Sampling valve prts are prvided n the servactuatr fr sampling the hydraulic fluid at the primary inlet and at the return. (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Servvalve trque mtr cils are designed with insulated wiring with mutual insulatin resistance f 50 meghms minimum, with 500 vdc test ptential applied and a dielectric strength capable f withstanding vlts RMS, 60 Hz between insulated turns withut breaking dwn r a current leakage f nt mre than 500 micramperes between actuatr husing r cil turns. (Cil r Electrical Filter is Open r Shrted) The trque mtr cils are designed fr cntinuus peratin at 100 t 140 milliamperes. The peratinal (rbiter) cmmand currents are limited t + 55 ma per ICD In additin, sftware (rbiter limits n actuatr cmmands are impsed which are equivalent t 20 ma frm T -20 minutes t T secnds and 44.9 ma frm T secnds t separatin. (Cil r Electrical Filter is Open r Shrted) The electrical filter ceramic capacitrs are rated at 50 VDC.The resistrs are wirewund with a pwer rating f 2 watts at 25 C and a temperature cefficient f 0+20 PPM/ C. The capacitrs and resistrs are lt traceable with identificatin data included in each shipment. The filter elements are ptted within a husing made f 304 r 302 CRES material t prevent filter element damage r shrting. (Cil r Electrical Filter is Open r Shrted)

3 FM Cde: A04 Date: March 1, 2002 Trque mtr cil lead wires are tefln insulated. Cnductrs rated fr 600 VAC and 200 C. The lead wires are cvered with heat shrink tubing and are ruted and supprted between the cil husing and the cnnectr. (Cil r Electrical Filter is Open r Shrted, Damaged Electrical Cnnectr) Sldering meets the requirements f NASA NHB (3A-1) r NHB (3A-2). (Cil r Electrical Filter is Open r Shrted, Damaged Electrical Cnnectr) External cnnectrs are sealed, underwater type that have been qualified fr SRB applicatin. Metal prtective caps are prvided fr installatin n the cnnectrs at all times except when access is required fr test and flight cable installatin. Lubricants, cmpatible with cnnectr O-ring seals, are prvided t facilitate cnnectr installatin and mating. (Damaged Electrical Cnnectr) The servactuatr (including servvalves) is designed t a service life f 200,000 cycles with inch displacement at 10.0 Hz; 200,000 cycles with inch displacement at 10.0 Hz; 4,000 cycle with inch displacement at 0.25 Hz and 400 cycles with inches displacement at 0.1 Hz. The servvalve assembly, as part f the servactuatr, was subjected t qualificatin testing which verified the design requirements, including a burst pressure cnducted at Mg. The test results are reprted in Qualificatin Test Reprt MSFC-RPT-900. The Mg cnducted burst pressure testing results are reprted in Mg Reprt N. MR T Tw units were subjected t qualificatin testing. After cmpletin f the MSFC/Mg cnducted testing, the tw units were trn dwn and inspected. There was n evidence f wear, damage r ther anmalies as reprted in Mg dissassembly and inspectin analysis reprts, MR M-2982 and MR M (All Failure Causes) B. TESTING VENDOR RELATED TESTING Servactuatr Acceptance Tests are perfrmed per Mg Reprt N. MR A This prcedure includes: (All Failure Causes) - Servvalve Trque Mtr Cils - Cmmand Current Limiting Respnse - Servvalve Pressure Gain - Failure Respnse - Dynamic Acceptance Tests - Cleanliness - Cil Dielectric Strength Tests - Cil Insulatin Resistance Test - Examinatin f Prduct CN 044 A tw minute flushing prcedure is perfrmed when a hydraulic line is remved r reinstalled per Mg ATP MR A (Bth Nzzles r Drain Orifices Clgged By Cntaminatin, Clgged fluid Filter)

4 FM Cde: A04 Date: March 1, 2002 Refurbished servactuatrs are tested as fllws: - End Item Acceptance Test per Mg MR A This is the same ATP as new hardware except sme cmpnent level tests are nt required when teardwn des nt affect the validity f the previus cmpnent test. These cmpnent tests are Pwer Valve Pressure Gain, Transient Lad Relief Valve and Servvalve Differential Pressure Transducers. KSC RELATED TESTING Helium is verified fr cleanliness and cmpsitin (purity and particulate cunt) prir t intrductin t n-bard circuits per 10REQ-0021, para (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Hydraulic fluid is verified fr cleanliness and cmpsitin (purity and particulate cunt) prir t intrductin t n-bard hydraulic circuits per 10REQ-0021, para (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Effluent hydraulic fluid is verified fr misture cntent and cleanliness (water cntent and particulate cunt) frm the rck actuatr, the tilt reservir, the rck reservir and the tilt actuatr per 10REQ-0021, para (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Actuatr respnse t predefined input cmmands during htfire, per 10REQ-0021, paras and Actuatr null, linearity and plarity and servvalve redundancy verificatin tests are perfrmed per 10REQ-0021, para Hydraulic fluid is verified fr cleanliness and cmpsitin (purity and particulate cunt) prir t intrductin t n-bard hydraulic circuits during prelaunch peratins per OMRSD File V, Vl. 1 Requirement Number B42HPO.010. (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Ascent Thrust Vectr Cntrl/SRB-TVC system respnse t predefined input cmmands per OMRSD File II, Vl. 1 Requirement Number S (Gain Test). Dynamic peratin f the Ascent Thrust Vectr Cntrl/SRB-TVC System Failure Detectin and Islatin Circuitry per OMRSD File II, Vl. 1 Requirement Numbers S and.680. (Individual Channel Test)

5 FM Cde: A04 Date: March 1, 2002 Frequency respnse (gain and phase) and step respnse f the Ascent Thrust Vectr Cntrl/SRB-TVC system per OMRSD File II, Vl. 1 Requirement Numbers S and.750 respectively. Gimbal test perfrmed after SRB HPU start under cntrl f autmated sftware in GLS and RSLS verifies actuatr perfrmance by mnitring actuatr psitin, servvalve differential pressure, islatin valve events and APU turbine speed (related t actuatr pressure switch). Pass/fail criteria fr autmated prtins f terminal cuntdwn are cntrlled per OMRSD File II, Vl. 1, requirement number S00FSO.030 and launch cmmit criteria. This is the last test that verifies actuatr perfrmance. The abve referenced OMRSD testing is perfrmed every flight. C. INSPECTION VENDOR RELATED INSPECTIONS USA SRBE PQAR witnesses final servactuatr ATP accrding t USA SRBE SIP USA SRBE PQAR verifies hydraulic fluid is inspected fr cntaminatin befre lading accrding t USA SRBE SIP (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) USA SRBE verifies all material certificatins in accrdance with USA SRBE SIP USA SRBE PQAR perfrms visual inspectin f unit paying special attentin t cnnectr pins per USA SRBE SIP During refurbishment and prir t reuse, the servactuatr is disassembled, cleaned, inspected and tested t ensure prper perfrmance per 10SPC Preliminary evaluatin includes: - Clean and inspect external surfaces - CN Disassembly as required t inspect the bdy/cylinder interface and bushing, spl and sleeve assemblies f the: selectr valve, lck valve, servvalves and pwer valve fr evidence f seawater cntaminatin. Extent f repair is determined frm this evaluatin and accmplished per the fllwing general requirements: - Ttal disassembly is required if any wetted hydraulic surface disclses seawater cntaminatin

6 FM Cde: A04 Date: March 1, All nnhermetic electrical/electrnic parts which have been expsed t seawater are replaced. - All repairs are prcessed by the cgnizant Material Review Bard. - All seals which have been remved frm the installed psitin r expsed t seawater cntaminatin are replaced. - All hydraulic surfaces that have been expsed t seawater cntaminatin are recleaned per Mg Dcuments , supplement 32 and MR-Q Reassembly per the same prcedures and cntrls as new hardware. Critical Prcesses/Inspectins: - Sldering per QQ-S-571 and NHB5300.4(3A-1) r NHB (3A-2) KSC RELATED INSPECTIONS Helium cleanliness and cmpsitin (purity and particulate cunt) are verified prir t intrductin t n-bard circuits per 10REQ-0021, para (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Hydraulic fluid cleanliness and cmpsitin (purity and particulate cunt) are verified prir t intrductin t nbard hydraulic circuits per 10REQ-0021, (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) The misture cntent and cleanliness (water cntent and particulate cunt) f the effluent hydraulic fluid frm the rck actuatr, the tilt reservir, the rck reservir and the tilt actuatr are verified per 10REQ-0021, para (Clgged fluid Filter, Bth Nzzles r Drain Orifices Clgged by Cntaminatin) Prper functin f TVC system is demnstrated during htfire peratins per 10REQ-0021, para (All Failure Causes) Hydraulic fluid cleanliness and cmpsitin (purity and particulate cunt) are verified prir t intrductin t nbard Hydraulic circuits during prelaunch peratins per OMRSD File V, Vl. 1, Requirement Number B42HP SRB TVC actuatr psitining test is verified per OMRSD File II, Vl. 1 Requirement Number S Bth SRB individual channel null test and actuatr individual channel ramp test are verified per OMRSD File II, Vl. 1 Requirement Numbers S and.680 respectively. Bth SRB actuatr frequency respnse and step respnse are verified per OMRSD File II, Vl. 1 Requirement Numbers S and.750 respectively

7 FM Cde: A04 Date: March 1, 2002 D. FAILURE HISTORY Failure Histries may be btained frm the PRACA database. E. OPERATIONAL USE - Nt applicable t this failure mde