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NASA/TM-2011-217182/Volume I NESC-RP-09-00596 Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel versus the Aluminum (Al) Y-Channel Primer Chamber Assemblies (PCAs) Roberto Garcia/NESC Langley Research Center, Hampton, Virginia Regor L. Saulsberry Whte Sands Test Facility, Las Cruces, New Mexico October 2011

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NASA/TM-2011-217182/Volume I NESC-RP-09-00596 Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel versus the Aluminum (Al) Y-Channel Primer Chamber Assemblies (PCAs) Roberto Garcia/NESC Langley Research Center, Hampton, Virginia Regor L. Saulsberry Whte Sands Test Facility, Las Cruces, New Mexico National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-2199 October 2011

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The use of trademarks or names of manufacturers in the report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration. Available from: NASA Center for AeroSpace Information 7115 Standard Drive Hanover, MD 21076-1320 443-757-5802

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 1 of 50 Pyrovalve Booster Interface Temperature Measurement Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel versus the Aluminum (Al) Y-Channel Primer Chamber Assemblies (PCAs) July 21, 2011 NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 2 of 50 Pyrovalve Booster Interface Temperature Measurement Approval and Document Revision History NOTE: This document was approved at the July 21, 2011, NRB. This document was submitted to the NESC Director on August 22, 2011, for configuration control. Approved: Original Signature on File 8/22/11 NESC Director Date Version Description of Revision Office of Primary Effective Date Responsibility 1.0 Initial Release Mr. Roberto Garcia, NASA 7/21/11 Technical Fellow for Propulsion; Mr. Regor Saulsberry, Pyrotechnic and Propulsion Component Testing, JSC - WSTF NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 3 of 50 Pyrovalve Booster Interface Temperature Measurement Table of Contents Volume I: Technical Assessment Report 1.0 Notification and Authorization..................................................................................................... 6 2.0 Signature Page................................................................................................................................ 7 3.0 Team List........................................................................................................................................ 8 3.1 Acknowledgements.......................................................................................................................... 8 4.0 Executive Summary....................................................................................................................... 9 5.0 Assessment Plan ........................................................................................................................... 11 6.0 Background and Problem Description....................................................................................... 12 6.1 Prior Pyrovalves Failures To Ignite Booster Propellant during Ground Testing........................... 12 6.2 MSL Project PCA Material and Flow Passage Design Changes ................................................... 12 6.3 MSL Project SS V-Channel PCA Testing ..................................................................................... 13 6.4 Limitations of the SS V-Channel PCA Design.............................................................................. 14 6.5 NESC Testing – Test Apparatus .................................................................................................... 14 6.5.1 Test Article Mounting and Alignment Fixture .............................................................................. 17 6.5.2 NSI Firing Systems ........................................................................................................................ 17 6.5.3 Kennedy Space Center (KSC) DPIC ............................................................................................. 17 6.5.4 JSC - WSTF Dual NSI Initiator Set............................................................................................... 18 6.6 Data Acquisition and Control System............................................................................................ 19 6.7 Phase I Testing............................................................................................................................... 20 6.8 Phase II Testing ............................................................................................................................. 21 7.0 Data Analysis................................................................................................................................. 25 7.1 Modified SS V-Channel PCA Test ................................................................................................ 38 7.2 PCA Thermal Analysis .................................................................................................................. 42 7.2.1 Conclusions.................................................................................................................................... 42 7.3 Phases I and II Statistical Analysis ................................................................................................ 43 7.4 Numerical Simulations of Single and Simultaneous Dual Firing Initiators in the SS V-Channel PCA Design ................................................................................................................................... 45 8.0 Findings, Observations, and NESC Recommendations............................................................ 46 8.1 Findings ......................................................................................................................................... 46 8.2 Observations .................................................................................................................................. 47 8.3 NESC Recommendations............................................................................................................... 47 9.0 Alternate Viewpoints ................................................................................................................... 47 10.0 Other Deliverables ....................................................................................................................... 48 11.0 Lessons Learned........................................................................................................................... 48 12.0 Definition of Terms...................................................................................................................... 48 13.0 Acronyms List .............................................................................................................................. 49 14.0 References..................................................................................................................................... 50 NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 4 of 50 Pyrovalve Booster Interface Temperature Measurement List of Figures Figure 5.0-1. Comparison of Al Y-Channel PCA (Heritage) to SS V-Channel PCA (MSL: CRES-V) ............................................................................................................... 11 Figure 6.3-1. Typical SS V-Channel PCA Pyrovalve ............................................................................ 13 Figure 6.5-1. Sapphire Window Interface Simulating the Booster Container showing a Al Y-Channel PCA ................................................................................................................ 15 Figure 6.5-2. Sapphire Window System Parts showing a SS V-Channel PCA...................................... 15 Figure 6.5-3. Sapphire Window Assembly (dimensions in inches) ....................................................... 16 Figure 6.5-4. Sealing Rings Shown Alongside a U.S. Dime .................................................................. 16 Figure 6.5-5. PCA Test Article Mounting and Alignment Fixture......................................................... 17 Figure 6.5-6. KSC DPIC......................................................................................................................... 18 Figure 6.5-7. WSTF Dual NSI Initiator Set............................................................................................ 19 Figure 6.6-1. JSC - WSTF Data Acquisition and Control System ......................................................... 20 Figure 6.8-1. Phase IIA Test Matrix As Performed................................................................................ 22 Figure 7.0-1. NSI Firings Run 2 ............................................................................................................. 26 Figure 7.0-2. Typical Results from a Single NSI Firing in an Al Y-Channel PCA (Run 4) .................. 27 Figure 7.0-3. Typical Results for a Single NSI firing in a SS V-Channel PCA (Run 15)...................... 28 Figure 7.0-4. Booster Propellant Interface Temperature Results for Phase I Tests................................ 29 Figure 7.0-5. Temperature and Pressures Versus Time for Phase I, Run 15, SS V-Channel PCA, Single NSI Firing .............................................................................................................. 29 Figure 7.0-6. Temperatures and Pressures for Phase I, Run 9, Al Y-Channel PCA, Single NSI Firing................................................................................................................................. 30 Figure 7.0-7. NSI Current versus Time, Phase I..................................................................................... 30 Figure 7.0-8. Phase I- Post-Test Images of Booster Charge Cover Simulators, Sapphire Windows, and Sealing Rings ............................................................................................................. 31 Figure 7.0-9. Phase IIA Run 4 ................................................................................................................ 33 Figure 7.0-10. Phase IIA, Run 1A ............................................................................................................ 34 Figure 7.0-11. Data from Phase IIA, Run 4 Showing the Negative Pressure Readings in the Vicinity of the First NSI Firing......................................................................................... 35 Figure 7.0-12. Data from Phase IIA, Run 4 showing the Negative Pressure Readings in the Vicinity of the Second NSI Firing .................................................................................................. 35 Figure 7.0-13. Phase IIB, Run 1 Instrumentation Checkout Test shows No Negative Pressure Readings when Current is Applied to the NSI Simulators (Resistors) ............................. 36 Figure 7.0-14. Images Captured from Phase II High-Speed Video Camera ............................................ 37 Figure 7.1-1. SS V-Channel PCA Modified With Two Resonant Chambers......................................... 39 Figure 7.1-2. SS V-Channel PCA with Two Resonant Chambers ......................................................... 40 Figure 7.1-3. Comparison of a Dual, Simultaneous NSI Firing With and Without a Modified SS V-Channel PCA ................................................................................................................ 41 Figure 7.1-4. Sealing Ring, Sapphire Window, and Booster Charge Cover Simulator from the Modified SS V-Channel PCA........................................................................................... 42 List of Tables Table 6.5-1. Comparison of KSC DPIC and JSC – WSTF Dual NSI Initiator Set............................... 18 Table 6.7-1. Modified Phase I Test Matrix ........................................................................................... 21 Table 6.8-1. Original Phase IIB Test Matrix......................................................................................... 23 Table 6.8-2. Updated Phase IIB Test Matrix......................................................................................... 24 NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 5 of 50 Pyrovalve Booster Interface Temperature Measurement Table 7.0-1. Phase I Test Data Summary.............................................................................................. 25 Table 7.0-2. Phase II Test Data Summary............................................................................................. 32 Table 7.0-3. Phase II High-Speed Video Data Summary...................................................................... 38 Table 7.3-1. Summary Table of Response Means and 95 Percent Confidence Intervals on the Means................................................................................................................................ 44 Volume II: Appendices (separate volume) Appendix A. Pyrometer Measurements with a Hole Pre-Cut in the Booster Cover Simulator Appendix B. Pyrometer Noise Appendix C. Pressure Transducer Drop Test Appendix D. Assessment of Area versus Temperature Indication Appendix E. PCA Thermal Analysis Appendix F. Statistical Phase I Analysis and Results Appendix G. Statistical Analysis of Phase II Analysis and Results Appendix H. Numerical Simulations of Single and Simultaneous Dual Firing Initiators in the SS V-PCA Design NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 6 of 50 Pyrovalve Booster Interface Temperature Measurement Volume I: Technical Assessment Report 1.0 Notification and Authorization Mr. Roberto Garcia, NASA’s Technical Fellow for Propulsion, requested a technical assessment of the performance improvement achieved by the introduction of the stainless steel (SS) V-channel compared to the aluminum (Al) Y-channel Primer Chamber Assembly (PCA) design. The SS V-channel PCA was developed for NASA’s Mars Science Laboratory (MSL) Project. The principle focus of the assessment was to measure the transient temperature at the booster interface with both designs. A NASA Engineering and Safety Center (NESC) Technical Assessment was approved at an outof-board on November 4, 2009. Mr. Regor Saulsberry, at the NASA Johnson Space Center (JSC) - White Sands Test Facility (WSTF), was selected to lead this assessment. The assessment plan was approved by the NESC Review Board (NRB) on November 19, 2009. Version 2.0 of the plan provided additional testing to evaluate the effects of various staggered firing times (skew) and flow path cross-sectional areas. The updated plan was approved on May 27, 2010. A status briefing for Phase I was presented to the NRB on May 6, 2010. The final report was presented for approval on July 21, 2011. Key stakeholders for this assessment include NASA, NASA contractors, other government agencies, and outside contractors involved in spacecraft fabrication and operations. This includes most space exploration programs such as Space Launch System, the Multi-Purpose Crew Module (MPCV), MSL, Earth observing programs, and commercial spacecraft programs. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 7 of 50 Pyrovalve Booster Interface Temperature Measurement 2.0 Signature Page Submitted by: Team Signature Page on File – 9/26/11 ___________________________________ Mr. Roberto Garcia Date Significant Contributors: ___________________________________ Mr. Stephen H. McDougle Date ___________________________________ Mr. Kenneth L. Johnson Date ___________________________________ Mr. Anthony D. Carden Date ___________________________________ Ms. Sandra Verba Date ___________________________________ Mr. Regor L. Saulsberry Date ___________________________________ Mr. Adam A. Pender Date ___________________________________ Ms. Asia N. Quince Date ___________________________________ Mr. William Sipes Date Signatories declare the findings and observations compiled in the report are factually based from data extracted from Program/Project documents, contractor reports, and open literature, and/or generated from independently conducted tests, analysis, and inspections. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 8 of 50 Pyrovalve Booster Interface Temperature Measurement 3.0 Team List Name Discipline Core Team Organization Roberto Garcia NASA Technical Fellow for Propulsion MSFC Regor Saulsberry NESC Assessment Lead JSC - WSTF Stephen McDougle Deputy Assessment Lead MEIT, JSC - WSTF Tony Carden Electrical Engineer Ken Johnson Statistics Loutricia Johnson Program Analyst Adam Pender Propulsion Systems Asia Quince Pyrotechnics William Sipes Pyrotechnics Devices ERC, Inc., WSTF MSFC LaRC Lockheed Martin JSC Jacobs, JSC - WSTF Sandra Verba Sr. Program Mgr Aerospace/Pyrovalves Conax Florida Corporation Consultants Saverio D'Agostino Materials and Processes Carl Guernsey MSL Prop System JPL JPL Michael Hagopian Propulsion Systems Components GSFC Masashi Mizukami MSL Prop System JPL Troy Rayner Senior Propulsion Engineer Lockheed Martin NASA Technical Fellow for Passive Steve Rickman Thermal Analysis JSC Aerospace Engineering Supervisor - Robert Sadenwater Pyrovalves Keith Van Tassel Pyrotechnic Systems Richard Webster Pyrotechnic Systems Stephen Woods Propellant Physicist Conax Florida Corporation JSC JPL Jacobs, JSC - WSTF Zachary Zenz Pyrovalve Design Engineer Conax Florida Corporation Administrative Support Tina Dunn-Pittman Project Coordinator LaRC/ATK Donna Gilchrist Planning and Control Analyst LaRC/ATK Erin Moran Technical Writer 3.1 Acknowledgements LaRC/ATK NESC Resident Engineer, Ms. Courtney Flugstad, is acknowledged for her initial lump mass heating calculations for zirconium potassium perchlorate (ZPP) burning. NESC Resident Engineer, Mr. Brian Anderson, is acknowledged for his investigation of compression heating. Cobham and its subsidiary, Conax Florida Corporation, are acknowledged for their technical support and for providing the SS PCAs used for this assessment. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 9 of 50 Pyrovalve Booster Interface Temperature Measurement 4.0 Executive Summary In October 2008, the NASA Engineering and Safety Center (NESC) generated a report entitled, Conax Y-PCA (Primer Chamber Assembly) Booster Anomaly Investigation [ref.1]. This report detailed an independent assessment of four spacecraft propulsion system pyrovalve anomalies that occurred during ground testing. In all four cases, the aluminum (Al) PCA featuring a Y-channel and dual NASA Standard Initiators (NSI) was used. In the ground tests, the nearly simultaneous (i.e., separated by less than 20 microseconds (μs)) firing of both initiators failed to ignite the booster charge. In 2007 as a result of the then ongoing NESC’s assessment, the Mars Science Laboratory (MSL) project team decided to modify PCA design in the attempt to minimize the identified weakness of the Al Y-channel PCAs. Two modifications were made: the PCA body was changed from Al to stainless steel (SS) to avoid melting and distortion of the NSI flow passages when the device functioned; and the interconnected flow passages were separated to a V-channel in an effort to more efficiently transfer energy from the NSIs to the booster charge. MSL project development and qualification testing of the SS V-channel PCA design demonstrated improved performance in terms of shorter booster ignition times and greater thermal margin for booster ignition. However, the 2008 NESC report recommended that the SS V-channel PCA should be experimentally characterized and quantitatively compared to the Al Y-channel PCA design prior to widespread application to NASA programs and project. This NESC assessment is intended to generate this quantitative comparison of the PCA designs. In the first phase of this assessment, single and dual simultaneous firings of the NSIs were performed in both PCA types to characterize the peak temperature, pressure rise time, and pressure magnitude delivered to the booster membrane/propellant charge interface (i.e., underside of the booster charge cover). The results indicated the SS V-channel PCAs delivered an average maximum booster/propellant interface temperature approximately 600 °F greater than that delivered by the Al Y-channel PCAs. The higher interface temperature was achieved in one-half the rise time (i.e., 776 versus 1,342 μs for the SS V-channel and the Al Y-channel PCAs, respectively). Pressures in the NSI cavity averaged 3,000 psi greater in the SS V-channel than the Al Y-channel PCAs. Finally, the testing showed that simultaneous (i.e., within 20 μs) NSI firing significantly reduces the performance of either PCA design to the point where it is unlikely that the booster charge would be reliably ignited. This is consistent with findings from previous NESC assessments [ref. 1]. The booster interface temperature needed to ignite the titanium hydride/potassium perchlorate booster charge is approximately 1,000 °F. In some simultaneous test firings the maximum temperature observed was below the lower limit (i.e., 572 °F) that could be detected by the test instrumentation. The second phase of this assessment evaluated the effects of NSI staggered firing times (skew) and PCA flow passages cross-sectional area of the SS V-channel PCAs. This testing showed that even with flow paths having 4 times the original cross-sectional area, simultaneous (i.e., within NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 10 of 50 Pyrovalve Booster Interface Temperature Measurement 20 μs) NSI firings significantly reduces performance to the point where it is doubtful that the booster charge would be reliably ignited. In addition, the flow paths with enlarged cross-sections (i.e., areas 2 and 4 times greater than the original design) did not consistently produce significantly higher temperatures at the booster interface. When the flow path diameter and the skew were high, the combined factors exerted a downward effect on peak pressure. The flow paths with cross-sectional areas 2 and 4 times greater than the original design produced lower pressures in the NSI cavity (i.e., about 1,600 psi and 2,400 psi, respectively). This was not unexpected due to the larger free volume with enlarged flow paths. Near-simultaneous firings resulted in lower temperatures and booster charge cover burn-through percentages. Proof of concept testing of a prototype PCA resonant chamber modification was conducted. However, additional analysis and testing is required to determine if this design feature has the 1 potential to eliminate the requirement for a minimum NSI firing skew time. Because the assessment did not conduct tests with booster charges, the ability to actuate the pyrovalve was not directly demonstrated. However, the results of this assessment provide spacecraft designers that use pyrovalves with quantitative information regarding PCA selection and reliable use. In summary, this assessment characterized the SS V-channel PCAs have greater thermal margin for booster ignition and resistance to sidewall burn-through, but has a higher unit weight than the Al Y-channel PCA design. However, Al and SS PCAs will reliably ignite the booster if a minimum NSI firing skew is used. For the SS V-channel PCA design, increasing the flow path diameter with high skew times reduced the maximum pressures inside the PCA, but an insufficient number of tests were conducted to determine with certainty that the peak temperature difference increased with channel diameter. 1 Minimum NSI firing skew is a function of the design specific pyrovalve firing circuit. Critical factors influencing effective skew include temperature, NSI current, cable length, PCA material. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 11 of 50 Pyrovalve Booster Interface Temperature Measurement 5.0 Assessment Plan The MSL project is using pyrovalves with SS dual NSI PCAs rather than the more common Al PCAs (see Figure 5.0-1). The SS design with separate flow paths for each NSI appears to address several design shortcomings of the Al PCA with a “Y” shaped flow path. These shortcomings were identified by the NESC’s investigation into four failed pyrovalve events [ref. 1]. However, the NESC report recommended the SS PCA design, which appears to offer greater margin towards successful booster charge ignition, should be experimentallycharacterized and quantitatively compared to the Al PCA design. This assessment was constructed to provide this quantitative data. In addition to augmenting the MSL project testing, the NESC data will benefit future projects to properly assess the selection and use of the SS V-channel versus the Al Y-channel PCAs. Figure 5.0-1. Comparison of Al Y-Channel PCA (Heritage) to SS V-Channel PCA (MSL: CRES-V) In this two-phased investigation, tests will be conducted to quantify the difference between the two PCA types in ignition temperature delivered to the underside of the booster charge cover (propellant interface). Tests will be performed with single and dual simultaneous NSI firings, varying skew times, and flow path cross section. Testing will use the NESC dual pyrovalve initiator circuit (DPIC) to maintain the skew for simultaneous firings (i.e., within 20 μs) to provide a relative comparison to the NESC Conax Pyrovalve Ignition Failure test data [ref. 1] with the Al PCA design. Evaluation of the peak temperature and duration on the propellant side of the booster charge cover is a key gauge of the effectiveness of the PCA design in delivering energy from the NSI(s) to the booster charge. By extension, the rapid temperature rise above the booster propellant minimum ignition temperature requirements provides a relative comparison of ignition margin NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 12 of 50 Pyrovalve Booster Interface Temperature Measurement and helps with analysis of valve reliability. This will provide a foundation for more extensive use of the SS PCA dual NSI design on other spacecraft. 6.0 Background and Problem Description 6.1 Prior Pyrovalves Failures To Ignite Booster Propellant during Ground Testing In the 2005 and 2006 timeframe, four spacecraft propulsion system pyrovalve failures occurred during ground testing. In all four cases, the nearly simultaneous (skew estimated 5 to 70 μs) firing of dual initiators failed to ignite the booster charge. The Al PCA manufactured by Conax was used. The ZPP combustion products from the dual initiators were directed through a Y-shaped flow channel towards the booster charge. The NESC conducted an independent assessment of these failures [ref. 1]. 6.2 MSL Project PCA Material and Flow Passage Design Changes Because the MSL design used a number of mission critical pyrovalves, the MSL project team decided to modify the PCA design to minimize potential anomalies that were associated with the Al PCAs (done in 2006 and 2007). Two key design deficiencies were noted: (1) the PCA Al body material exhibited melting and erosion when the device functioned potentially resulting in decrease of thermal margin and increasing the chance of burn-through; and (2) the interconnected and angled flame passages could be blocked at the intersection. Additional motivation for the design change was provided by the observation that the heritage PCA design often exhibited long (>1 milliseconds (ms)) delays between NSI firing and booster ignition, with booster ignition occurring after the flow within the PCA had ceased. The MSL project team maintained the flow passage areas, initiator interfaces, and other PCA design attributes not related to the flow path layout. The other proposed changes in the NESC report such as enlarging or shortening the NSI flow passages were not implemented. The first design modification was to change the body material from 7075 Al to 15-5 SS. The SS material was selected for its strength and higher melting point. Next, the flow passages were separated into a “V-channel” configuration to provide independent flow passages from the initiator ports to the booster cavity. This approach ensures the initiator combustion products are directed to the top of the booster charge before they can flow to the other (unfired) initiator port. The flow towards the unfired initiator port was shown in the Y-channel design to divert a significant portion of the overall flow. This “bypass” flow and erosion/melting of the Al passage walls at the junction resulted in a significant heat transfer loss. The internal, open volume of the V-channel PCA was maintained equal to that of the Y-channel PCA so that the initiators would produce the same pressure effects. This was judged to be important because the booster charge output is intended to drive the pyrovalve ram and not to flow back into the initiator cavities. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 13 of 50 Pyrovalve Booster Interface Temperature Measurement 6.3 MSL Project SS V-Channel PCA Testing The initial testing of the SS V-channel PCAs was identified as development tests, as shown in Figure 6.3-1. For these tests, the PCAs were instrumented with pressure transducers in the initiator ports and in a fixture attached to the PCA outlet. This fixture had a 0.122-cubic-inch internal volume to simulate the volume of a pyrovalve piston in the post-stroke condition. There were 37 development tests performed covering a range of temperatures, initiator skew times, and booster charge. Initiators with 70, 100, and 120 percent of the nominal propellant load were used to establish booster ignition thermal margin. The development tests included nine tests of the Al Y-channel PCA design and 28 tests of the CRES-V design. The tests, using the heritage design, with the same test equipment and lot of initiators, validated the test set-up. Figure 6.3-1. Typical SS V-Channel PCA Pyrovalve In all of the development tests, the SS V-channel PCAs held an advantage in booster ignition as shown by shorter ignition times which were inferred to mean greater ignition with initiator loads that were as low as70 percent of nominal. After the successful completion of the development testing, the MSL project team proceeded into qualification testing. To qualify the design, 80, 100, and 120 percent initiators were tested in two different V-channel PCA size configurations at temperatures ranging from -31 to 158 ºF. All 40 (20 for each valve size) firings were successful, confirming the shorter booster ignition times and improvements over the heritage design consistent with those observed during the development tests. Finally, the SS V-channel PCAs were tested on assembled pyrovalves. The ¾-inch pyrovalve qualification phase included 27 fired units, while the 3/8-inch pyrovalve was subjected to a 9-unit delta qualification test. In all cases, the V-channel PCAs met requirements. Four NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 14 of 50 Pyrovalve Booster Interface Temperature Measurement additional PCAs were actuated in ground test unit pyrovalves, bringing the total number of actuations to 106 for the MSL-specific testing. The MSL-specific PCA testing is documented in Conax TR-397, “Closed Bomb Qualification Test Report, Stainless Steel PCA’s for Primer Chamber Assemblies,” dated July 11, 2007. 6.4 Limitations of the SS V-Channel PCA Design The SS V-channel PCA design met the intended objectives of the MSL testing, but it did not eliminate the possibility of flow stagnation during simultaneous initiator firings and subsequent failure to ignite the booster charge. Therefore, an operational constraint of firing with a minimum skew of 16 ms was specified for the MSL pyrovalves, with margin tests demonstrating ignition capability/margin with NSI skew times of 8 ms. Although the SS V-channel PCA design was qualified for use in the MSL project, improvements in temperature and pressure delivered to the booster interface were not quantified. 6.5 NESC Testing – Test Apparatus The Al Y-PCAs used for this project are detailed in Conax drawing number 1125-289-mi. These are the -03 size. The SS V-PCAs used are documented on Conax drawing number 1125-311-C1. These are the -04 size. All phases of the test project used a sapphire window arrangement in the booster location. The configuration is shown in Figures 6.5-1 and 6.5-2. The test apparatus consisted of a sealing ring, a booster charge cover simulator (0.003-in thick SS membrane), the sapphire window, and a spacer ring. The parts were held in place by a retaining nut on the bottom of the PCA. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 15 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 6.5-1. Sapphire Window Interface Simulating the Booster Container showing a Al Y-Channel PCA Figure 6.5-2. Sapphire Window System Parts showing a SS V-Channel PCA NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 16 of 50 Pyrovalve Booster Interface Temperature Measurement The booster charge cover simulator was made from 304L, supplied by Caran Precision, Inc., who produce the booster container. Before test, one side of the booster charge cover simulators were coated with flat black paint to provide a consistent emissivity. The coated-side was oriented toward the infrared (IR) pyrometer. The sapphire window was chosen because of its excellent transmissivity in the IR range. A 4-percent loss across the window was estimated. As the same sapphire window material was used in all tests, the energy loss was a constant (see Figure 6.5-3). The sealing ring (see Figure 6.5-4) was made from either 17-4PH or 15-5PH SS. Concentric rings were cut in faces to make a labyrinth seal between the sapphire window and the PCA. The sealing arrangement was successfully hydrotested to 30,000 pounds per square inch gauge (psig) with no detectable leakage. Figure 6.5-3. Sapphire Window Assembly (dimensions in inches) Figure 6.5-4. Sealing Rings Shown Alongside a U.S. Dime One pressure sense port for each NSI cavity was provided in the side of the PCA. The ports were made to accommodate Kistler model 603B1 pressure transducers. The ports were filled with Dow Corning 33 silicone grease to occupy the volume added by the transducer port and to protect the pressure sensor from NSI thermal/shock effects. The IR pyrometer used for the tests was a model MI-KGA740-HS manufactured by Mikron Infrared, Inc. This unit had a temperature range of 572 to 3,632 ºF with a nominal response time of 6 μs. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 17 of 50 Pyrovalve Booster Interface Temperature Measurement High-speed video was obtained at 20,000 frames per second with a Phantom™ model 12.1 color camera. This configuration allowed evaluation of the transient temperature at the underside of the booster charge cover, which is normally in contact with the booster propellant. 6.5.1 Test Article Mounting and Alignment Fixture The test article mounting fixture consists of a precision three axis translation stage with a custom machined test article mounting assembly affixed to the upper (Y) stage. The entire assembly is rigidly mounted to the test bed. The assembly provides precision alignment capability for the high-speed pyrometer and is shown with a PCA test article assembly in Figure 6.5-5. Figure 6.5-5. PCA Test Article Mounting and Alignment Fixture 6.5.2 NSI Firing Systems During the course of NESC testing, two NSI firing systems were utilized. Both systems provide high current, approximately 22.5 amps to the NSIs. Normal firing current for the NSIs is usually in the range of 3 to 5 amps. The higher current was used in this project to reduce variations in firings times. These two systems are discussed in the following sections. 6.5.3 Kennedy Space Center (KSC) DPIC This firing system (Figure 6.5-6) was designed for the NESC and built by KSC in July 2006, and was designed to fire the two NSIs simultaneously. The NSIs are connected in series. The system provides outputs for current and voltage monitoring, data acquisition, and camera NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 18 of 50 Pyrovalve Booster Interface Temperature Measurement systems triggering. It is controlled remotely with an arm/fire pendant which contains the safe/arm key switch, firing button, and indicator light emitting diodes. Figure 6.5-6. KSC DPIC 6.5.4 JSC - WSTF Dual NSI Initiator Set For Phases IIA and B of the test program, JSC - WSTF designed and built a dual NSI firing system with variable skew capability (Figure 6.5-7). The circuitry for this system was modeled on the KSC DPIC system and designed using information in Johnson Space Center (JSC) 28596A, NASA Standard Initiator User’s Guide. Both the KSC and WSTF systems utilize capacitive discharge type firing circuits as recommended by JSC-28596A. The fundamental differences between the KSC and WSTF systems are summarized in Table 6.5-1. Table 6.5-1. Comparison of KSC DPIC and JSC – WSTF Dual NSI Initiator Set KSC DPIC JSC – WSTF Dual NSI Initiator Set Voltage (VDC) 65 Firing Circuits/Amperage (amps) 1/22.5 Monitoring None Control Manual NESC Request No.: 09-00596 24 2/22.5 NSI current, and data acquisition and highspeed camera triggering Computer

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 19 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 6.5-7. WSTF Dual NSI Initiator Set 6.6 Data Acquisition and Control System The data acquisition and control system (Figure 6.6-1) consists of a National Instruments PXI (PCI Extension for Instrumentation) chassis with one National Instruments NI PXI-5105 8-channel high-speed digitizer for capturing high-speed transients, and one NI PXI-6229 multifunction data acquisition and control card for firing system control. The data acquisition and control system is capable of simultaneous sampling rates of up to 60 MHz (60 million samples per second) and is fully configurable using the JSC-WSTF software package. The software package was written in C language and was validated before testing began. For NSI port pressure measures, two each Kistler model 603B1 charge mode pressure transducers with Kistler model 5010 charge amps were utilized. All PCA test articles were machined to accept one pressure transducer in each NSI port. The transducers were installed using a Kistler model 222P needle probe adapter in each port, and protected by the Dow Corning 33 silicone grease. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 20 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 6.6-1. JSC - WSTF Data Acquisition and Control System 6.7 Phase I Testing All tests were performed at ambient test cell temperatures approximately 60 to 75 °F. The original test plan for Phase I identified 16 test firings to be performed in the order shown in Table 6.7-1. See Appendix F for discussion of the approach used to design the Phase I test matrix. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 21 of 50 Pyrovalve Booster Interface Temperature Measurement Table 6.7-1. Modified Phase I Test Matrix Run Single or Dual PCA Type No. NSI Test 1 Al Dual 2 SS Single 3 Al Single 4 Al Single 5 Al Dual 6 SS Dual 7 SS Single 8 Al Single 9 Al Single 9B Al Single 10 Al Dual 11 Al Dual 12 SS Dual 13 SS Dual 14 SS Single 15 SS Single 16 SS Dual 1 Comment 1 Not Performed 2 Repeated Test 1 Not Performed 1 Not Performed 1 Not Performed 1 Not Performed 1 Not Performed Because of the test results and the recommendation to proceed with a second phase of testing, test matrix was reduced to 10 test firings. 2 One of the tests with an Al Y-channel PCA was repeated due to concerns with potential seal leakage, so there were a total of 11 test firings. See Appendix G for a thorough discussion of the approach used to design the test matrix for Phase I. 6.8 Phase II Testing Phase IIA In Phase IIA, the flow passages of select SS V-channel PCAs used in Phase I testing were planned to be enlarged to determine if the larger flow cross-sectional area results in higher temperatures at the booster interface. These trial tests were single NSI firings. The original plan (Figure 6.8-1) called for evaluation of cross-sectional areas 2, 4, 6, and 8 times that of the original flow passage. However, it was recognized that 4 times the original cross-sectional area was the largest that could be accommodated. Dual, simultaneous NSI firings were performed at NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 22 of 50 Pyrovalve Booster Interface Temperature Measurement 4 times the cross-sectional area to determine if this configuration has potential to eliminate the dual simultaneous firing restriction (i.e., minimum skew time) on the PCA. Flow Channel Cross-Sectional Run # Skew Area Test Order NSIs (μs) (Initial = 1) 2 4 2 16,000 4 4 1 2 16,000 2 3A 2 2 16,000 1 1A 3 2 12 4 Repeat of Test 3 which had an incorrect skew. Repeat of Test 1 which had a cracked sapphire window. Figure 6.8-1. Phase IIA Test Matrix As Performed The test matrix was designed to be run in a random order to reduce the effects of uncontrolled variables (e.g., generally, special causes). The actual run order was amended because of the need to correct PCA housing dimensional problems. A no-fire occurred on the first trial run, which had a skew of 12 μs. This run showed that a larger channel diameter (i.e., 4 times the flow path) would not eliminate the chance of a no-fire. It was decided not to run the remaining 0-skew trials. Three additional trials from the Phase IIA matrix, each at 16,000 μs skew, were completed. The assessment team did not run enough of the Phase IIA trail tests to be able to say with certainty that the peak temperature difference increased with channel diameter. This question was the basis of the revised Phase IIB test matrix. Phase IIB After Phase IIA testing was completed, 17 additional tests were planned to further investigate the impact of staggered NSI firings at various area ratios, as shown in Table 6.8-1. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 23 of 50 Pyrovalve Booster Interface Temperature Measurement Table 6.8-1. Original Phase IIB Test Matrix Flow Path Test Cross-Sectional Run Article Area Ratio Order No. Skew (μs) (Initial = 1) 1 10 252.5 2 2 3 500 4 3 1 500 1 4 8 500 1 5 1 252.5 2 6 7 5 1 7 6 5 1 8 8 5 2 9 7 252.5 2 10 10 252.5 4 11 9 252.5 1 12 1 5 4 13 4 252.5 2 14 8 500 4 15 7 5 4 16 5 500 2 17 2 252.5 2 Phase IIB was designed to determine the relationship between firing skew, flow passage crosssectional area, booster interface temperature, and the interaction term of skew x area. The test was structured to be able to discern a second-order (quadratic) linear model: 2 2 Y = β0 + β1 Skew + β2 Area + β12 Skew x Area + β11 Skew + β22 Area where the β’s are linear regression parameters fit using the data. Power was based on the temperature response. The assessment team wanted to observe a difference of 1,000 °F with greater than 80 percent power (~2 standard deviations, based on the Phase I results). The assessment team used design of experiments (DOE) principles to plan the test. An orthogonal matrix ensured that all factors (i.e., β’s) would be calculable, with no noise NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 24 of 50 Pyrovalve Booster Interface Temperature Measurement or confounding contributed by other factors. It was desired that the standard error would be constant across the design space, resulting in a good estimate of model parameters and predictions at all points in the domain. The original Phase IIB matrix was randomized to avoid problems with rogue variables. To avoid thermal and surface roughness effects of re-using previously fired PCAs, it was originally planned that used PCAs would have a larger chamber area before re-use. It was later decided for the 1X flow path area tests to clean used PCAs between runs to minimize the number of units. This resulted in some PCAs being reused 3 times. Following cleaning, PCAs were visually-inspected to verify there was no degradation. Further, an anomalous result happened in the first trial and the trial was re-run using another PCA. An attempt to re-randomize the test sequence for this issue was made, resulting in the updated matrix shown in Table 6.8-2. Table 6.8-2. Updated Phase IIB Test Matrix If there is an effect of times used, the data is suboptimal to separate that factor from the others. As a lesson learned, it would have been better to design the test blocked on number of times used. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 25 of 50 Pyrovalve Booster Interface Temperature Measurement 7.0 Data Analysis Phase I test data is summarized in Table 7.0-1. Table 7.0-1. Phase I Test Data Summary Phase 1 DATA SUMMARY Single NSI Firings Time Of Pressure Max Max Pressure Time Of Max Booster Max Max Booster Time Of Pressure Pressure Interface Start Press Start Pressure Press Interface Max at 800 μs at 800 μs Temp at Al Pressure - or - Side A Side A Side A Side B Run SS Date Time (μs) (psig) (μs) (μs) Pre SS 02/23/10 13:56 137 11,851 151 332 2 SS 02/24/10 12:34 140 10,926 156 255 7 SS 02/25/10 9:40 147 10,781 166 324 14 SS 02/25/10 13:41 144 10,436 159 314 15 SS 02/25/10 14:55 147 11,085 169 259 Average 145 10,807 163 288 3 Al 03/01/10 13:29 130 8,001 156 319 4 Al 02/26/10 8:48 143 6,881 157 286 8 Al 02/26/10 9:29 138 8,199 154 297 9 Al 03/01/10 14:02 155 6,560 160 292 9B Al 04/06/10 137 9,445 154 307 Average 141 7,817 156 300 Side B Side B Temp Temp Side A Side B 800 μs (psig) (μs) (°F) (μs) (psig) (psig) (°F) 4,996 830 2,679 716 4,777 4,840 2,669 4,570 824 2,823 835 4,638 4,527 2,836 4,996 787 1,967 821 4,933 4,979 1,957 4,441 870 1,885 726 4,690 4,232 1,842 4,805 845 2,485 721 4,811 4,614 2,352 4,703 832 2,290 776 4,768 4,588 2,247 2,269 1,440 1,691 1,064 3,857 1,716 1,404 1,650 1,241 1,308 1,053 2,938 1,580 1,133 1,860 1,480 1,412 913 3,337 1,307 1,264 1,848 1,130 2,902 804 3,077 1,762 2,894 2,149 1,445 1,154 2,875 3,892 1,820 846 1,955 1,347 1,693 1,342 3,420 1,637 1,508 Dual Simultaneous NSI Firings 6 SS 02/24/10 15:06 152 10,419 168 151 1 Al 03/01/10 14:43 149 6,456 164 149 9,735 168 ----- ---- 9,252 9,196 ---- 6,244 163 719 10,210 4,863 4,857 --- NOTES 1 The pyrometer does not read temperatures below 572 °F 2 "Side A" refers to the the fired side in a single NSI firing test; "Side B" is inert 3 All times are measured from the start of the firing pulse (increase in amps) The four single NSI firings with SS V-channel PCAs produced an average maximum temperature of 2,290 ºF. In each test, the NSI produced a nearly circular hole punched or melted in the booster charge cover simulator, as shown in Figure 7.0-1. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 26 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-1. NSI Firings Run 2 Five single NSI firings were conducted with Al Y-channel PCAs. One of the runs, Run 9, had a maximum temperature of 2,902 ºF, which was much higher than any of the other run. Evidence of impact, external carbon deposits, and fractures in the sapphire window from this run led to suspicion that sealing arrangement leaked and the booster charge cover simulator may have been penetrated by particulate. Excluding this run gives an average maximum temperature of 1,391 ºF for the remaining four Al Y-channel PCAs. All of the maximum temperatures were above 1,000 ºF, which is the temperature judged to be sufficient to ignite the booster charge. Figure 7.0-2 shows typical results for a representative single NSI firing in an Al Y-channel PCA. The pressure oscillations at the event start are due to the interaction of pressure transducer with the grease filled sense port channels. To estimate the true peak pressure for the test, a subset of the pressure data is used for a second order polynomial curve fit. The starting data point is determined using the value of the second pressure peak. Using this value, the pressure data earlier in the test is examined until a corresponding value is found. The subset ending data point is chosen where the pressure oscillations have dampened. This ending data point is at 800 μs after the trigger signal. The resulting second order polynomial curve-fit is then extrapolated to the intersection with the initial pressure rise curve. This intersection is the estimate of true peak pressure. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 27 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-2. Typical Results from a Single NSI Firing in an Al Y-Channel PCA (Run 4) As the NSI flow continues from the PCA active to the inactive side, the pressures begin to equalize. When the pressures equalize, there is no further driving force for flow. In this case, flow stopped about 1,300 μs after the initial 1,000 psig pressure rise. The maximum temperature at the booster interface occurs just prior to flow termination. For comparison, Figure 7.0-3 shows typical results for a representative single NSI firing in a SS V-channel PCA. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 28 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-3. Typical Results for a Single NSI firing in a SS V-Channel PCA (Run 15) In comparing Figures 7.0-2 and 7.0-3, it is evident the true peak pressure is higher (average 38 percent) with the SS than the Al PCA. Also, the pressure equalization and the maximum temperature occur earlier in the SS PCAs (i.e., 700 versus 1,300 μs). Since booster charge response was out of scope for this assessment and was not fired in this test series, further testing is needed to understand the effect the pressure difference would have on a pyrovalve function. Figures 7.0-4 through 7.0-8 show the booster interface temperature results for Phase I tests. The Al Y-channel PCA results are shown by the black lines, while the SS V-channel PCA results are shown by the red lines. Figure 7.0-4 shows that the SS V-channel PCAs produce higher temperatures on average than the Al Y-channel PCAs. Figures 7.0-5 and 7.0-6 show the images obtained with the high-speed video (visual range) camera superimposed on a plot of the booster charge interface temperatures and NSI cavity pressures versus time. Figure 7.0-7 shows the current traces for all the Phase I tests. As shown in the figure, this provides information about the timing of various events occurring in the test articles. Notice that the event timing is consistent in all the tests. This is partly due to the high firing current of 22 amps that was used to minimize any minor ignition differences in the NSIs. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 29 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-4. Booster Propellant Interface Temperature Results for Phase I Tests Figure 7.0-5. Temperature and Pressures Versus Time for Phase I, Run 15, SS V-Channel PCA, Single NSI Firing NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 30 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-6. Temperatures and Pressures for Phase I, Run 9, Al Y-Channel PCA, Single NSI Firing Figure 7.0-7. NSI Current versus Time, Phase I NESC Request No.: 09-00596

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1.0 Version: Page #:31 of 50 Document #:09-00596 NESC-RP- Technical Assessment Report NASA Engineering and Safety Center Figure 7.0-8. Phase I- Post-Test Images of Booster Charge Cover Simulators, Sapphire Windows, and Sealing Rings : Pyrovalve Booster Interface Temperature Measurement Title NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 32 of 50 Pyrovalve Booster Interface Temperature Measurement Table 7.0-2. Phase II Test Data Summary Time Of Max Press Time Of Max Time Of Max Max Channel Actual Max Booster Before Max Pressure Booster Pressure Test Phase Run No. Diameter Skew Press Interface Side B Press Side A Interface Side B (inch) (μs) Side A Temp Rise Side B (psig) (μs) (°F) (psig) (μs) Temp (psig) (μs) 2B 1 0.060 6 10,437 225 - NA NA 9,781 235 2A 3A 0.060 16,000 9,641 224 3,410 16,434 1,574 13,039 16,057 2B 4 0.060 486 11,389 224 2,913 1,132 2,532 15,076 713 2B 5 0.060 485 10,780 220 3,078 1,161 5,661 15,371 710 2B 7 0.060 5 9,715 223 1,723 217 NA 10,719 229 2B 11 0.060 235 10,670 228 2,275 825 2,494 13,344 460 Average 10,439 224 2,680 3,954 3,065 12,888 3,067 2A 4 0.085 16,000 7,838 225 3,402 16,460 1,456 10,145 16,052 2B 2B 0.085 236 8,618 222 1,837 2,555 3,018 13,734 466 2B 6A 0.085 250 9,440 212 1,896 1,578 5,765 12,212 461 2B 8 0.085 0 10,010 240 2,095 246 NA 10,477 240 2B 13 0.085 237 9,017 219 1,733 1,208 3,208 14,220 459 2B 9 0.085 242 8,493 222 2,517 965 3,140 13,094 461 2B 14A 0.085 8 9,637 224 1,723 220 NA 10,146 232 2B 16 0.085 484 8,435 222 3,312 803 4,074 14,027 717 2B 17 0.085 236 8,828 220 2,315 770 3,052 12,826 468 Average 8,924 223 2,314 2,756 3,388 12,320 2,173 2A 1A 0.120 12 9,321 168 - NA NA 8,908 156 2A 2 0.120 16,000 6,852 213 3,479 16,285 1,562 9,692 16,211 2B 3A 0.120 488 8,243 214 3,630 299 4,140 10,114 700 2B 10 0.120 243 7,500 219 2,501 648 3,528 11,546 458 2B 12 0.120 5 9,208 215 1,957 216 NA 9,785 221 2B 14 0.120 484 7,208 219 3,630 774 3,528 10,389 706 2B 15 0.120 5 9,161 222 699 3,700 NA 9,077 237 Average 8,213 210 2,649 3,654 3,190 9,930 2,670 NOTES: All times are from the start of the firing signal A red highlight indicates a temperature too low to ignite the booster propellant A dash "-" indicates a temperature lower than the 572 °F lower limit detectable by the pyrometer This means that the temperature could be anywhere between 72 °F and 572 °F Phase II testing utilized SS V-channel PCAs and evaluated the effects of NSI skew and PCA flow passage cross-sectional area (Table 7.0-2). The SS V-channel PCAs were modified to have NSI flow passages with cross-sectional areas 2 and 4 times larger (0.085 and 0.120 inches, respectively) than the original design. Phase IIA consisted of four tests. Tests were performed at each of the three different crosssectional areas: nominal (Run 3A), 2 times the normal cross-sectional area (Run 4), and 4 times the normal cross-sectional area (Runs 1A and 2). To maximize the data obtained from each of NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 33 of 50 Pyrovalve Booster Interface Temperature Measurement these firings, the second NSI would be fired with a skew of 16,000 μs. The exception to this plan was Run 1A, which had a skew of 12 μs. The fourth test was to be a dual, simultaneous firing at the maximum cross-sectional area of 4 times the normal. Had this fourth test been successful in producing sufficient temperature at the booster interface, additional dual, simultaneous firing tests would be performed with the enlarged flow passages. Figure 7-0.9 shows the NSI cavity pressure and the booster charge cover simulator temperature as a function of time. For Run 4, the flow passages were enlarged to twice the normal crosssectional area. Both NSIs were fired in this test with a stagger time of 16,000 μs. It is evident in the figure that the PCA responded as if there were two separate NSI firings, each of which produced a maximum temperature in the 3,200 to 3,300 °F range. The three Phase IIA tests with NSI skew of 16,000 μs produced a maximum temperature at the booster interface ranging from 3,402 to 3,479 °F. Thus, there appears to be no practical benefit from enlarging the flow passages with a 16,000 μs skew as far as maximum booster interface temperature is concerned. Figure 7.0-9. Phase IIA Run 4 Figure 7.0-10 shows the NSI cavity pressure and booster charge cover simulator temperature as a function of time. Run 1A was a dual, simultaneous firing with flow passages enlarged to 4 times the normal cross-sectional area. The skew in this test was 12 μs. As shown in the figure, there was no detectable increase in booster interface temperature. This means that the temperature was below the pyrometer lower temperature detection limit of 572 °F. This temperature is insufficient to ignite the booster propellant (i.e., approximately 1,000 °F). Therefore, even with enlarged flow passages with 4 times the normal cross-sectional area, dual, simultaneous firing remains a potential failure mode. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 34 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-10. Phase IIA, Run 1A In the majority of the Phase IIA tests, the pressure data went negative prior to the pressure rise (Figures 7.0-11 and 7.0-12). The negative values observed were approximately -500 psig. In these figures, the pressure scale is extended to -1,000 psig and the time scale expanded in the vicinity of the pressure rise from each of the two NSI firings. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 35 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-11. Data from Phase IIA, Run 4 Showing the Negative Pressure Readings in the Vicinity of the First NSI Firing Figure 7.0-12. Data from Phase IIA, Run 4 showing the Negative Pressure Readings in the Vicinity of the Second NSI Firing An investigation was performed to help understand why this occurred. This effect was not seen in instrumentation pre-test checkouts. These checkouts were performed routinely beginning with Phase IIB (Figure 7.0-13). NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 36 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.0-13. Phase IIB, Run 1 Instrumentation Checkout Test shows No Negative Pressure Readings when Current is Applied to the NSI Simulators (Resistors) In these instrumentation checkouts, the test apparatus was configured identical to the planned PCA test. The only difference was that resistors are used to simulate the NSIs. In Figure 7.0-13, current is applied to the resistors 115 μs after the trigger signal. It is evident that there is no effect on either pressure or the temperature readings. Electrical effects from the plasma that is formed inside the NSI when the ZPP ignites may cause the negative pressure response. However, further investigation is required to determine the root cause. The testing continued at this point since the minor initial pressure dip did not appear to affect the data in the area of interest or change any conclusions. Phase IIB continued to characterize the effects of skew and enlarged flow passages. Nominal skews of 5, 252.5, and 500 μs were tested with V-channel PCAs having flow passages with cross-sectional areas 1, 2, and 4 times that of the baseline design. The 5 μs skew was selected as a target to evaluate dual, simultaneous firing effects, while providing data at a skew greater than 0. Similarly, 500 μs was chosen to provide separation in firing times, while still evaluating possible interactions. The midpoint 252.5 μs and the 2 times the cross-sectional area were used so that a quadratic regression model could be fit to the data where necessary. This results approximately in a face-centered cubic efficient experimental design. The flow paths with 2 and 4 times the cross-sectional area did not consistently produce greater temperatures at the booster interface. These cross-sectional areas did produce lower pressures in the NSI cavity (about 1,600 psi and 2,400 psi, respectively). This was not unexpected due to the larger free volume with enlarged flow paths. Firings with attenuated temperatures and membrane burn-through percentages occurred predictably at nominally 0 skew. Figure 7.0-14 shows the images captured from a high-speed NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 37 of 50 Pyrovalve Booster Interface Temperature Measurement video camera aimed at the underside of the booster charge cover simulator. In each case, the image was selected to illustrate the maximum effect on the simulator (Table 7.0-3). Note that because the simulator is an opaque metal disk, combustion gases and particles are only visible following disk penetration. Figure 7.0-14. Images Captured from Phase II High-Speed Video Camera NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 38 of 50 Pyrovalve Booster Interface Temperature Measurement Table 7.0-3. Phase II High-Speed Video Data Summary Image No. Phase Run No. Channel Dia (in) Skew (μs) 1 2A 1A 2 2A 2 3 2A 2 4 2A 3A 5 2A 3A 6 2A 4 7 2A 4 8 2B 1 9 2B 2B 10 2B 3 11 2B 4 12 2B 5 13 2B 6A 14 2B 7 15 2B 8 16 2B 9 17 2B 10 18 2B 11 19 2B 12 20 2B 13 21 2B 14 22 2B 14 23 2B 15 24 2B 16 25 2B 17 7.1 Modified SS V-Channel PCA Test 0.120 12 0.120 16000 0.120 16000 0.06 16000 0.06 16000 0.085 16000 0.085 16000 0.06 6 0.085 236 0.120 481 0.06 486 0.06 485 0.085 250 0.06 5 0.085 0 0.085 242 0.120 243 0.06 235 0.120 5 0.085 237 0.120 484 0.120 484 0.120 5 0.085 484 0.085 236 To supplement this study, computational fluid dynamics (CFD) modeling was performed by ® Craftech (reference Section 7.5 and Volume II, Appendix E). The work was performed under NASA Phase I Small Business Innovation Research (SBIR) Topic No. X2.01-9934, “Design NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 39 of 50 Pyrovalve Booster Interface Temperature Measurement Support and Analysis Tool for Pyrotechnically Actuated Valves,” Contract No. NNX11CG13P, Report No. 01/C472. The CFD modeling indicated that chambers machined adjacent to the flow channels reduced the tendency toward the stagnation condition that caused low booster interface temperatures during simultaneous firings. This was thought to have the potential for eliminating the requirement for minimum skew. A SS V-channel PCA with the normal 0.060-inch diameter 3 flow channels was modified to have two resonant chambers (total volume 0.00789 in ) as shown in Figure 7.1-1. Figure 7.1-1. SS V-Channel PCA Modified With Two Resonant Chambers To investigate the CFD analysis, a special dual, simultaneous NSI firing (5 μs skew) test was performed (Figure 7.1-3). Phase IIB Run 1 data is plotted for comparison. The maximum temperature on Run 1 was below the minimum detectable limit of the pyrometer (572 °F). The maximum temperature on the resonant chamber test was 782 °F, which is below the minimum temperature of 1,000 °F to ignite the booster charge. Therefore, this specific resonant chamber modification did not eliminate the potential failure mode resulting from the dual, simultaneous NSI firing. This investigation was proof of concept only, and not intended to be a rigorous examination of resonant chamber volume versus PCS design and NSI skew. Figure 7.1-2 is a photograph of the modified V-channel PCA showing the location of the two resonant chambers. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 40 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.1-2. SS V-Channel PCA with Two Resonant Chambers The new chambers are the larger diameter holes. The smaller holes are the normal 0.060-inch diameter flow channels from the NSIs. A dual, simultaneous NSI test firing was performed with this test article. The results are shown in Figure 7.1-3. Phase IIB Run 1 data is plotted on the same graph for comparison. Both were dual, simultaneous firings with nominal (0.060-inch diameter) flow passages and 6 μs skew. The maximum temperature on Run 1 was below the minimum detectable limit of the pyrometer (572 °F). The maximum temperature on the resonant chamber test was 782 °F. Previous test work has shown that in this rapid temperature rise situation, 1,000 to 1,100 °F is needed to ignite the booster. Therefore, this specific modification did not eliminate the potential failure mode resulting from the dual, simultaneous NSI firing. However, the added 0.00789-cubic-inch volume was less than what was modeled and due to budget limitations, testing was not done with larger added volumes. The NESC, or future programs considering applying the modification, would need to plan on additional testing. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 41 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.1-3. Comparison of a Dual, Simultaneous NSI Firing With and Without a Modified SS V-Channel PCA Post-test examination revealed little damage to the booster charge cover simulator, which is consistent with other dual, simultaneous NSI firing tests where the membrane is not breached. See Figure 7.1-4. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 42 of 50 Pyrovalve Booster Interface Temperature Measurement Figure 7.1-4. Sealing Ring, Sapphire Window, and Booster Charge Cover Simulator from the Modified SS V-Channel PCA 7.2 PCA Thermal Analysis To quantify the contribution of various heat transfer mechanisms in the booster charge cover thermal response, simplified and detailed thermal analyses were performed. These analyses are provided in Appendix E, with conclusions summarized in the following section. 7.2.1 Conclusions Three heat transfer mechanisms and their effect on booster cap thermal response were investigated as part of this study. From the analysis, the following conclusions are drawn: a. Convective heat transfer, by itself, may not account for the temperature rise and melting during booster cap testing. Further computational and/or empirical quantification of gas temperatures and heat transfer coefficients are needed to draw a definitive conclusion as to whether convection alone is sufficient. b. Zirconia deposition and the subsequent phase change from the liquid to solid state may assist in booster cap heating and subsequent melting but does not produce booster cap temperatures in agreement with the booster cap transient temperature response observed during testing. Larger quantities of zirconia deposition increase the propensity to melt and accelerate the temperature rise of the booster cap bottom. c. Unburned ZPP deposition can liberate sufficient energy to locally melt through the booster cap as indicated by detailed thermal analysis of a hemispherical globule of ZPP -3 -3 -8 with a radius of 3.6u10 in with a mass of 5.2u10 mg (1.14u10 lbm). Deposition of as -5 little as 20 percent of the unburned ZPP (~4.6 mg, or 1u10 lbm) can liberate sufficient energy to melt the entire booster cap. Subsequent two-dimensional axisymmetric thermal NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 43 of 50 Pyrovalve Booster Interface Temperature Measurement analysis shows that local melt-through can be accomplished with considerably less ZPP. From this, it is concluded that << 4.6 mg ZPP burning in contact with the booster cap is sufficient to produce the observed response. While heat transferred by convection and by the phase change of liquid zirconia deposited on the booster cover simulator, the unburned ZPP results are a compelling indication that this mechanism could be a viable alternative mechanism. There would presumably be a lot of variation in the quantity, size and impingement locations of unburned ZPP that could explain inconsistent performance of the NSIs. 7.3 Phases I and II Statistical Analysis This section provides a summarization of the statistical analysis and results from the Phase I and Phase II testing. More complete analysis information is provided in Volume II, Appendices F and G. Phases I and IIB were conducted using DOE principles: 1. A clear statement of the problem was developed for each phase. The problem statements were testable, of defined scope, and agreed upon by the entire assessment team. 2. Factors (inputs) and responses (outputs) were quantifiable, tractable, and measurable. 3. The domains over which the factors would be varied were broad enough to be able to discern in outputs, if they existed, and addressed the statements of problem. 4. The test matrices were defined taking these points into account and so the data would be analyzable, resulting in clear conclusions on which to base recommendations. The test matrices were to include randomization to ensure independence of data and minimize issues due to special causes, minimum correlation between factors (orthogonality) to ensure that the factors’ effects on the responses could be separated ensuring that there existed analysis methods to examine the data and other efficiencies. 5. Analysis of variance (ANOVA) and similar firmly-based methods were employed in the analysis. Most of these principles were followed. However, randomization was not fully performed, but the assessment team feels this did not seriously compromise the investigation conclusions. The assessment team generated robust experiments and the analysis results are clear in most cases. In the cases where they are not, it is concluded that this was not due to the experimental design, but rather to the phenomena tested being noisy and/ or there being little effect on the responses by these factors. Phase I was designed to quantify the difference between the Al Y-channel and SS V-channel PCAs in temperature measured at the simulated booster charge cover and in pressure in various parts of the system. It was also meant to, at a minimum, qualitatively and better quantitatively NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 44 of 50 Pyrovalve Booster Interface Temperature Measurement characterizes what happens at 0 skew time conditions and provides an idea of the range of response values to help design follow-on tests. All these goals were met. The two simultaneous firings showed less-desirable temperature responses than the single firings, and could have produced a no-fire condition. Analysis produced expected values (means) for a number of responses. Temperatures were both statistically and engineering-wise significantly higher for the SS runs than for the Al runs. Key pressure measurements were significantly higher for the SS runs in both statistical and engineering terms. Table 7.3-1. Summary Table of Response Means and 95 Percent Confidence Intervals on the Means ± 95 ± 95 Response SS Mean Al Mean Notes percent Time of Maximum Temperature 776 120 percent 959 120 Peak Temperature 2,290 °F 431 1,391 °F 431 Ignored Run 9 Temperature at 800 μs 2,247 °F 440 1,162 °F 440 Ignored Run 9 Time of Port A Pressure Ignored Run 9; included duals Rise Start 144 μs 5 137 μs 5 Port A Calculated Peak Ignored Run 9; included duals; Pressure 10,729 psi 289 7,796 psi 1,292 weighted analysis Port A Pressure at 800 μs 4,768 psi 406 3,420 psi 363 Time of Port B Pressure ~295 μs ~295 μs Difference not significant Rise Start Port B Calculated Peak 4,779 psi 313 1,895 psi 283 Included Duals Pressure Port B Time to Peak ~830 μs ~1,400 μs Runs 9 and 9B may be outliers Pressure Port B Pressure at 800 μs 4,588 psi 300 1,637 psi 269 Phase IIB was designed to evaluate the relationship between firing skew time and flow passage cross-sectional area. It was assumed that the following model could be used to describe these relationships: 2 2 Y = β0 + β1 Skew + β2 Area + β12 Skew x Area + β11 Skew + β22 Area where the β’s are linear regression parameters fit using the data and Y could represent any of the chosen response variables. Test results showed that within the tested range of flow passage area, a no-fire is likely to occur given near-simultaneous firings. The test was not designed to characterize the risk of no-fire with skew time. The assessment team cannot determine that the chance of a no-fire does or does not decrease to a negligible level at 500 μs skew given this data alone. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 45 of 50 Pyrovalve Booster Interface Temperature Measurement Analyses included characterization of a response surface for most output variables. Some are notional, and involve extrapolations in the area of 0 skew. Others appear to characterize the behavior of the responses adequately over the input factors’ domain. The assessment team performed a single confirmation run that could not be shown to invalidate the model predictions. The assessment team did not perform confirmation runs. The assessment team is satisfied the qualitative and quantitative conclusions are adequately supported by the data. Booster charge cover temperature, both peak and 1,600 μs after NSI ignition, depends statistically significantly on skew time, but not on flow passage cross-sectional area. The time to attain 1,000 °F at the Booster cover was not found to be statistically significantly predicted by skew of flow passage cross-sectional area. There were indications that another, unmeasured variable could have affected this measure. Pressures after the initial NSI firing were statistically significantly depressed by a combination of high skew time and high flow passage cross-sectional area. Longer skews promoted higher pressures after the second NSI initiation, but larger channel area diminished peak pressure after the second initiator firing. Pressure at 1,600 μs was statistically significantly lessened in highpassage cross-section area runs compared with low-area runs, but was not significantly affected by skew. Measurements and analysis of the booster charge cover hole size were problematic. Near 0-skew runs showed no burn-through. It appears reasonable that the data shows that higher skews correspond to larger burn-through areas, but flow passage cross-sectional area may not affect this. 7.4 Numerical Simulations of Single and Simultaneous Dual Firing 2 Initiators in the SS V-Channel PCA Design In addition to the PCA thermal analysis discussed in Section 7.2, SS PCA numerical simulations ® (computer modeling) were accomplished by Craftech under the SBIR program, in collaboration with this project. Details of this modeling are provided in Volume II, Appendix H. This numerical modeling effort, based on CFD modeling, provided an improved understanding of the gas and particle flow physics within the V-channel PCA. One of the primary issues explored by this test project, the dual simultaneous NSI ignition anomaly was explained as interaction of the shocks formed by the two NSIs and stagnation at the booster interface. The stagnation condition and reflected waives appeared to reduce the amount of ZPP particles (hot burning) from reaching the booster membrane, causing the membrane temperature to be dramatically lower. Modeling of a modified V-channel PCA with additional chambers either side of the flow channels also accomplished as discussed Section 7.1. 2 ® Ashvin Hosangadi, Jai Sachdev, and Roger Birkbeck, Combustion Research and Flow Technology, Inc. (Craftech ) NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 46 of 50 Pyrovalve Booster Interface Temperature Measurement 8.0 Findings, Observations, and NESC Recommendations 8.1 Findings The following findings were identified: F-1. The SS V-channel PCA units delivered improved performance in the following areas: a. An average maximum booster/propellant interface temperature approximately 600 °F greater than that delivered by the Al Y-channel PCA units. b. The SS V-channel PCAs delivered higher temperatures to the booster interface providing added assurance of booster propellant ignition (refer to Table 7.0-1). c. The higher temperatures with the SS V-channel PCAs were achieved in approximately one-half the time; 776 μs average for the SS V-channel PCAs versus 1,342 μs average for the Al Y-channel PCAs. d. The SS V-channel PCAs produced pressures in the NSI cavity that were approximately 3,000 psi greater than the Al Y-channel PCAs. F-2. The tests showed that dual, simultaneous firing of the redundant NSIs significantly reduces the performance of not only the Al Y-channel PCA design as found previously, but also the SS V-channel PCA design to the point where it is doubtful the booster charge would be reliably ignited. The threshold for “no fire” may be higher than 20 μs skew, but no failures were observed at 250 μs skew and higher. This testing was not designed to determine a relationship between skew and ignition reliability parametrically. The bounds of effects due to ‘simultaneous firing’, therefore, almost certainly lie above 20 μs and may be above 250 μs. a. The booster interface temperature needed to ignite the titanium hydride/potassium perchlorate booster charge is approximately 1,000 °F under rapid rise conditions present in the booster. b. In about 50 percent of the dual, simultaneous test firings the maximum temperature observed was below or just slightly above the lower limit of 572 °F that could be detected by the test instrumentation. F-3. Enlarging the flow passages, even up to 4 times nominal cross-section, did not mitigate the risk of unreliable booster charge ignition from dual simultaneous firings of redundant NSIs. F-4. The assessment did not show consistently greater temperatures with larger NSI flow channels at the booster interface. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 47 of 50 Pyrovalve Booster Interface Temperature Measurement 8.2 Observations The following observations were identified: O-1. When the flow path diameter and the skew are high, they exert a considerable downward effect on peak pressure. a. The flow paths with cross-sectional areas 2 and 4 times greater than the original design produced lower pressures in the NSI cavity. b. The reduction was about 1,600 psi and 2,400 psi, respectively. c. This was not unexpected due to the obviously larger free volume with the enlarged flow paths. O-2. Increasing the flow passage diameter from the original 0.060-in diameter to 0.120-in (4 times the original cross-sectional area) lowers the maximum pressure inside of the PCA by about 2,000 psi or about 21 percent. O-3. SS PCA modeling suggested that additional chambers machined into the PCA might preclude the stagnation condition and mitigate the anomaly. Fully exploring this mitigation was beyond the scope of this assessment. O-4. A new and innovative temperature measurement method was developed and used for this assessment that is accurate to within 50 °F over a range of 572 to 3,632 °F and has a rapid response time of 10 μs or less. 8.3 NESC Recommendations The following NESC recommendations are directed at the NASA Programs and Projects using PCAs: R-1. Ensure that NSI firing circuits are characterized under as-built design and all mission conditions to determine the effective NSI firing skew time, and implement a commanded firing time of dual NSI PCAs that is longer than this value. (F2) - MSL testing determined ignition capability/margin was 8 ms, and implemented a minimum skew of 16 ms. R-2. Use SS V-channel in preference to Al Y-channel PCAs due to their increased capability to reliably activate the booster charge. (F-1) R-3. Explore the merit of resonant chambers to determine if this design feature eliminates the requirement for a minimum NSI skew time. (O-4) 9.0 Alternate Viewpoints There were no alternate viewpoints identified during the course of this assessment by the NESC team or the NRB quorum. NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 48 of 50 Pyrovalve Booster Interface Temperature Measurement 10.0 Other Deliverables No unique hardware, software, or data packages, outside those contained in this report, were disseminated to other parties outside this assessment. 11.0 Lessons Learned No applicable lessons learned were identified for entry into the NASA Lessons Learned Information System (LLIS). 12.0 Definition of Terms Corrective Actions Changes to design processes, work instructions, workmanship practices, training, inspections, tests, procedures, specifications, drawings, tools, equipment, facilities, resources, or material that result in preventing, minimizing, or limiting the potential for recurrence of a problem. Finding A conclusion based on facts established by the investigating authority. Lessons Learned Knowledge or understanding gained by experience. The experience may be positive, as in a successful test or mission, or negative, as in a mishap or failure. A lesson must be significant in that it has real or assumed impact on operations; valid in that it is factually and technically correct; and applicable in that it identifies a specific design, process, or decision that reduces or limits the potential for failures and mishaps, or reinforces a positive result. Observation A factor, event, or circumstance identified during the assessment that did not contribute to the problem, but if left uncorrected has the potential to cause a mishap, injury, or increase the severity should a mishap occur. Alternatively, an observation could be a positive acknowledgement of a Center/Program/Project/Organization’s operational structure, tools, and/or support provided. Problem The subject of the independent technical assessment. Proximate Cause The event(s) that occurred, including any condition(s) that existed immediately before the undesired outcome, directly resulted in its occurrence and, if eliminated or modified, would have prevented the undesired outcome. Recommendation An action identified by the NESC to correct a root cause or deficiency identified during the investigation. The recommendations may be used by NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Page #: Title: 49 of 50 Pyrovalve Booster Interface Temperature Measurement the responsible Center/Program/Project/Organization in the preparation of a corrective action plan. Root Cause One of multiple factors (events, conditions, or organizational factors) that contributed to or created the proximate cause and subsequent undesired outcome and, if eliminated or modified, would have prevented the undesired outcome. Typically, multiple root causes contribute to an undesired outcome. 13.0 Acronyms List Al Aluminum ANOVA Analysis of variance Btu basic terminal unit CAD computer-aided design CFD computational fluid dynamics DOE design of experiments DPIC Dual Pyrovalve Initiator Circuit GSFC Goddard Space Flight Center IR Infrared JPL Jet Propulsion Laboratory L/D Ratio of length to diameter LaRC Langley Research Center lbf pounds per force lbm pounds mass MPCV Multi-Purpose Crew Module MSFC Marshall Space Flight Center MSL Mars Science Laboratory MTSO Management and Technical Support Office NESC NASA Engineering and Safety Center NRB NESC Review Board NSI NASA Standard Initiators PCA Primer Chamber Assembly SBIR Small Business Innovation Research SLS Space Launch System SS stainless steel THPP Titanium Hydride Potassium Perchlorate VDC voltage direct current WSTF White Sands Test Facility ZPP zirconium potassium perchlorate ZrO2 zirconium oxide NESC Request No.: 09-00596

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Document #: Version: NASA Engineering and Safety Center NESC-RP- 1.0 Technical Assessment Report 09-00596 Title: Page #: 50 of 50 Pyrovalve Booster Interface Temperature Measurement 14.0 References 1. Hagopian, Michael and Dibbern, Andreas, Conax Pyrotechnic Valve Failures Investigation, NASA/TM-20008-215548 (NESC-RP-08-111/06-009-E), October 30, 2008. 2. Lee, H.S., Estimating Heat Losses in Pyrotechnic Devices, AIAA-2005-3837, July 2005. 3. http://www.americanelements.com/zrox.html. 4. Sharafat, S., Kobayashi, A., Ogden, V., and Ghoniem, N., Development of Composite Thermal Barrier Coatings with Anisotropic Microstructure, Vacuum 59 (2000), pp. 185-193, Pergamon. 5. CAD file: Alum 1125-279-04.stp. 6. Computer File: NSI-29_No_Filter_V1_0.avi. 7. MCDOUGLE_PHOTO Model(1).pdf. Volume II: Appendices (separate volume) Appendix A. Pyrometer Measurements with a Hole Pre-Cut in the Booster Cover Simulator Appendix B. Pyrometer Noise Appendix C. Pressure Transducer Drop Test Appendix D. Assessment of Area versus Temperature Indication Appendix E. PCA Thermal Analysis Appendix F. Statistical Phase I Analysis and Results Appendix G. Statistical Analysis of Phase II Analysis and Results Appendix H. Numerical Simulations of Single and Simultaneous Dual Firing Initiators in the SS V-PCA Design NESC Request No.: 09-00596

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Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 01- 10 - 2011 Technical Memorandum 4. TITLE AND SUBTITLE 3. DATES COVERED (From - To) November 2009 - July 2011 5a. CONTRACT NUMBER Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel versus the Aluminum (Al) Y-Channel Primer Chamber 5b. GRANT NUMBER Assemblies (PCAs) 6. AUTHOR(S) Garcia, Roberto; Saulsberry, Regor L. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) NASA Langley Research Center Hampton, VA 23681-2199 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 869021.05.07.01.10 8. PERFORMING ORGANIZATION REPORT NUMBER L-20081 NESC-RP-09-00596 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) National Aeronautics and Space Administration Washington, DC 20546-0001 12. DISTRIBUTION/AVAILABILITY STATEMENT Unclassified - Unlimited Subject Category 20 Spacecraft Propulsion and Power Availability: NASA CASI (443) 757-5802 13. SUPPLEMENTARY NOTES 14. ABSTRACT NASA 11. SPONSOR/MONITOR'S REPORT NUMBER(S) NASA/TM-2011-217182/Volume I NASA's Technical Fellow for Propulsion, requested a technical assessment of the performance improvement achieved by the introduction of the stainless steel (SS) V-channel compared to the aluminum (Al) Y-channel Primer Chamber Assembly (PCA) design. The SS V-channel PCA was developed for NASA's Mars Science Laboratory (MSL) Project. The principle focus of the assessment was to measure the transient temperature at the booster interface with both designs. This document contains the findings of the assessment. 15. SUBJECT TERMS Primer Chamber Assembly; NASA Engineering and Safety Center; Pyrovalve Booster; Dual Pyrovalve Initiator Circuit 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT a. REPORT b. ABSTRACT c. THIS PAGE U U U UU 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF PAGES STI Help Desk (email: help@sti.nasa.gov) 19b. TELEPHONE NUMBER (Include area code) 55 (443) 757-5802 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18