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\u201cPayload Bay Doors will be cycled open then closed to support payload operations and to inspect the bulb seal repair completed earlier this week. LH2 storage tank replenishment and GO2 recharge operations are complete.\u201d<\/p>\n
The timeline continues to support the start of Launch Countdown (S0007) operations next week, while engineers still hold the one day of contingency \u2013 if required \u2013 in the flow. Last week\u2019s Interim Problem Report (IPR 29) is still undergoing closure, although it isn\u2019t causing any interruptions to operations.<\/p>\n
\u201cS0007 Launch Countdown preps are in work and will continue through the week. IPR 0029 Partial Pressure Oxygen (PPO2) sensor C failure to calibrate) update: Calibration will be performed today (Friday),\u201d added the NTD.<\/p>\n
A new IPR was added to status on Friday \u2013 only the 38th in the entire STS-132 flow \u2013 which will require a waiver, while pressurization tasks are conducted over the weekend.<\/p>\n
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\u201cNEW IPR 0038. While securing from S1006, Space Shuttle Main Engine (SSME) pneumatics system was secured prior to engine controller securing, causing the engines to blow down with engine bleed valves only, violating an OMRS (Operations and Maintenance Requirements and Specifications) requirement. Will seek a waiver of the requirement,\u201d added the report.<\/p>\n
STS-132 Specific Articles: http:\/\/www.nasaspaceflight.com\/tag\/sts-132\/<\/p>\n
\u201cWeekend Work OMS\/RCS OMS (Orbital Maneuvering System)\/RCS (Reaction Control System), SSME and MPS (Main Propulsion System) helium and nitrogen tank pressurization to flight mass (S0071) on Sunday.\u201d<\/p>\n
SSME FRR:<\/p>\n
Atlantis will fly with Main Engines 2052, 2051 and 2047, aiding Atlantis\u2019 ascent during first stage, and responsible for the completion of the eight and a half minute ride into initial orbit during second stage flight.<\/p>\n
The performance of the engines has been superb during the vast majority of the shuttle program, with recent FRRs showing hardly any items of interest for managers to discuss at the meetings. However, STS-132\u2019s FRR for the SSMEs was relatively packed with items.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A32.jpg\" "\\"A3\\"")
The first issue listed came via an observation at the pad with Atlantis\u2019 engines.<\/p>\n\u201cDescription: Walkdown Inspections of E2051, ME-2, nozzle 5007 identified two small nicks on nozzle tubes ~8 inches from aft manifold. Nicks occurred during repair of tube 1036 in June 2005,\u201d noted the Agency FRR presentation for the SSMEs, one of 50 FRR presentations available on L2.<\/p>\n
Walkdowns of the vehicle at several stages of the flow is a required procedure for the engineers tasked with ensuring the condition of the hardware remains perfect during processing and the pad flows.<\/p>\n
Following the discovery of the small nicks in the nozzle, a decision was made to either repair, or fly as-is with flight rationale.<\/p>\n
\u201cAnalysis: Detailed mold impression taken to determine depth. Structural analysis completed \u2013 CEI requirements maintained. Digital microscope inspection confirmed no cracks. Use-as-is disposition approval ECD (Engineering Control Board) \u2013 5\/5\/10,\u201d added the presentation.<\/p>\n
\u201cFlight Rationale Structural assessment shows CEI requirements maintained. Since the repair of tube 1036, the nozzle has undergone: A 5 cycle proof pressure test @ 8675 psi. 3 Ground Tests (including one unrestrained test). 2 Flights (STS-119 and STS-128). No leakage or anomalies have been noted in this area since the nicks occurred.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A41.jpg\" "\\"A4\\"")
As with all FRRs, the previous flight\u2019s IFAs (In Flight Anomalies) make up a large section of the next flight\u2019s FRR. Interestingly, STS-132\u2019s SSME FRR reviewed several flight\u2019s worth of IFA-level content, including previously unreported notes from STS-130.<\/p>\n\u201cIssue: Areas of discoloration, melted screen on Nozzle 5014 (Engine 2061). Concern is potential jacket annealing,\u201d added the FRR presentation, which referenced a potential concern the discoloration may have been caused by the engines experiencing higher than normal re-entry temperatures \u2013 an undesirable situation.<\/p>\n
\u201cThree observations: Small melted area of thermal protection system (TPS) screen. Similar occurrences on 5 previous flights. Screen melts at ~2600F. Discolored paint stencil on jacket in one flight. Normally occurs over multiple flights. Discolors in minutes at 400F, and seconds at 1900F. Hotwall surface discoloration\/bluing near hat bands 5 and 6. No record of similar hotwall bluing.<\/p>\n
\u201cInvestigation: Identify source of heat discoloration\/damage. Evaluate effects on nozzle.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A51.jpg\" "\\"A5\\"")
Lab tests were utilized to aid the investigation results, which found that outgassing \u2013 rather than higher heat exposure \u2013 is most probable cause of the bluing or discoloration.<\/p>\n\u201cCoolant tube bluing reproduced in lab tests: Initial testing with heat only. Temperature to blue >1200 F. Normal reentry temperatures 600 to 850 F. Manifold coloration did not indicate reentry temperatures above normal. Individual areas of bluing inconsistent with global heating of jacket,\u201d the investigation notes added.<\/p>\n
\u201cConclusion: Tube bluing during flight due to heat alone is unlikely \u2018out-gassing\u2019 \u2013 Nozzle 5014 gaps within spec, on high side of family. Each blued area surrounds a tube gap. Conclusion: outgassing is most probable cause of bluing on N5014.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A61.jpg\" "\\"A6\\"")
\u201cNozzle structural integrity assessment: Melted screen. Minor localized damage, repair per standard process. Stencil \u2013 No significant damage. No tube damage. No tube leaks post flight. No annealing or softening of nozzle jacket. Confirmed by oxalic acid etch testing. No jacket wrinkles or distortion. No effect on nozzle structural integrity.\u201d<\/p>\nIn order to gain flight rationale for STS-132, Atlantis\u2019 SSME nozzles were checked and found to be in excellent condition.<\/p>\n
\u201cFlight Rationale: Post flight inspections confirm Nozzle 5014 did not incur structural damage. Inspections and testing indicate tube discoloration occurred post-MECO (Main Engine Cut Off). No credible scenario to discolor hotwall while hydrogen coolant is flowing through tubes. Nozzles on STS-132 inspected and meet all requirements.\u201d<\/p>\n
The checks on STS-132\u2019s nozzles are of a greater interest than usual, given Engine 2051\u2019s nozzle is flying after 60 areas of repair were carried out, following a run of flights where corrosion at the pad resulted in numerous pinhole leaks \u2013 though none had any effect on performance or safety.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A451.jpg\" "\\"A45\\"")
The root cause was soon found, pointing back to the the lining of the nozzles becoming contaminated with chlorides on an application sponge during the flow, resulting in corrosion-related leaks.<\/p>\n\u201cIssue: First flight of Nozzle repaired for out of family number of leaks. Cause identified and validated. Nozzles 2031, 4027, 5007 and 2035 contaminated with chlorides resulting in corrosion leaks,\u201d confirmed the FRR presentation.<\/p>\n
\u201cChloride source identified as sponge applicator used during post flight processing (3x more chlorides than sea water). Chlorides combined with humid environment to accelerate corrosion in braze shrinkage cracks. Resulted in out of family number of microscopic corrosion leaks.\u201d<\/p>\n
The largest number of pinholes in a nozzle was recorded on STS-127, with 340 leaks noted on nozzle 2031. A large number of leaks was noted on nozzles for several flights, prior to a change of procedure with the application process \u2013 the removal of the use of a sponge, and extra protection out at the pad \u2013 solved the issue.<\/p>\n
Although it was feared some nozzles would have to be scrapped, all four nozzles that suffered from leaks have been repaired. The first repaired nozzle flying with STS-132 is number 5007, which suffered from 63 leaks during its role with STS-128.<\/p>\n
\u201cAll four subject nozzles successfully repaired per standard repair process: Standard Tungsten Inert Gas (TIG) overlay. Sectioning of samples validated repair technique. Size and spacing of repairs within previous experience. No indication of dense areas of corrosion,\u201d the presentation continued.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A73.jpg\" "\\"A7\\"")
\u201cIntegrity of repairs validated using Nozzle 2031 with operational pressure test to 109 percent power level. No repair leaks or failures. Corrective actions to mitigate future corrosion. Higher concentration corrosion inhibitor applied to extended area using compatible materials. Nozzle conditioned air purge in VAB and on Pad implemented to reduce environmental moisture.\u201d<\/p>\nAs noted, the leaks are a repair timeline and manifest issue, as opposed to a safety issue. The debut of a repaired nozzle will be in combination with two nozzles that have not suffered from the same problem.<\/p>\n
\u201cCorrosion leakage levels experienced are low and have large margin to engine performance effects. Worst case leakage on Nozzle 2031 (340 leaks) maintained large margin to redline limits.<\/p>\n
\u201cSTS-132 nozzle leakage history: ME-2 E2051 \u2013 Nozzle 5007 \u2013 Exposed to chloride contamination. All 63 corrosion leaks successfully repaired. ME-1 E2052 \u2013 Nozzle 5004 \u2013 No indication of chloride contamination. Leakage history low. ME-3 E2047 \u2013 Nozzle 2030 \u2013 No corrosion leakage detected, potentially exposed to chlorides.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A49.jpg\" "\\"A49\\"")
Flight rationale was reasonable easy to achieve, due to the lack of risk involved with flying a nozzle that has previously leaked, even if further leaks are observed during flight.<\/p>\n\u201cFlight Rationale: STS-132 units and all four repaired nozzles meet flight leakage criteria. Nozzles repaired using standard repair process. Corrosion inhibitor applied. Conditioned air purge minimizes environmental moisture. Overall leakage rate on corrosion nozzles remains low with respect to redline limits.<\/p>\n
\u201cLeakage well within limits safely demonstrated in ground test. Large margin to engine performance effect. No impact on measurable data in prior flights. Experience and analysis demonstrate large changes in leakage due to corrosion are not credible.\u201d<\/p>\n
Another issue was listed from STS-131, when one SSME\u2019s Advanced Health Monitoring System (AMHS) noted a problem at T+445 seconds. However, according to the FRR presentation, flight data noted no problems were caused on the engine itself.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/05\/A8.jpg\" "\\"A8\\"")
\u201cIssue: Disqualification of High Pressure Fuel Turbopump (HPFTP) 21 degree Accelerometer during STS-131 ascent. Background: Controller reporting indicated disqualification due to high noise floor. Disqualification requires fixed and synch noise floor levels above 3 Gs for two consecutive 50 msec cycles. Monitor disqualifies one accelerometer and switches from 3-of-3 to 2-of-2 voting logic,\u201d noted the FRR.<\/p>\n\u201cIf monitor disqualifies 2nd accelerometer on a turbopump, redline would be deactivated for that turbopump. Real time data indicated instrumentation spike and not turbopump anomaly. Momentary increase in synch and return to normal levels. Spike observed on only one of three accelerometers. Multiple spikes observed during chill \u2013 not unusual.\u201d<\/p>\n
With HPFTP accel noise spikes deemed as common, and a worse case scenario resulting in LOV\/C (Loss Of Vehicle\/Crew) as unlikely as 1 in 763, flight rationale was once again accepted, fully clearing Atlantis\u2019 SSMEs as ready for flight.<\/p>\n
\u201cAnalysis: Flight data analysis confirms nominal HPFTP performance. Post ascent AHMS memory dump data used to assess noise level. High noise floor confirmed as cause of disqualification. Measurement spiking not unusual. Algorithm designed to discriminate between instrumentation and turbopump anomalies.<\/p>\n
\u201cPredicted probability (2002) of disqualification of 1 sensor in 9 flights. Predicted probability (2002) of loss of redline 1 in 763 flights. AHMS functioned as designed.<\/p>\n
\u201cThe Atlantis Main Engines are in a ready condition for STS-132.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"
Engineers are heading into a weekend of critical operations for STS-132, as Atlantis undergoes flight pressurization operations on the systems that will aid her journey to the International Space Station (ISS) in a week\u2019s time. Wednesday\u2019s Agency Flight Readiness Review (FRR) focused on one of those systems \u2013 the Space Shuttle Main Engines (SSMEs) \u2013 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[3610,8116,3485],"class_list":["post-40786","post","type-post","status-publish","format-standard","hentry","category-news","tag-frr","tag-ssme","tag-sts-132"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40786"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=40786"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40786\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}