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Discovery\u2019s Payload Bay Doors (PLBD) were closed for the final time ahead of rollover to the Vehicle Assembly Building (VAB), as leak checks \u2013 set to be completed on Thursday \u2013 are carried out on the orbiter.<\/p>\n
\u201cFinal PLBD closure for rollover to the VAB; Stongbacks are scheduled to be removed Thursday,\u201d noted processing information on L2. \u201cECLSS (Environmental Control and Life Support System) GN2 72-hr decay test began Monday and will complete Thursday.\u201d<\/p>\n
Only two relatively minor issues are in work at this time, relating to the Data Processing System (DPS) and \u201cchallenges\u201d with the LH (Left Hand) ET Door.<\/p>\n
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STS-131 Specific Articles: http:\/\/www.nasaspaceflight.com\/tag\/sts-131\/<\/p>\n
![\"A3\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/01\/A313.jpg\" "\\"A3\\"")
\u201cNew IPR 0022 to DPS \u2013 taken when MFD1 (Multifunction Display) failed to switch to secondary data port when requested,\u201d noted the NASA Test Director (NTD). \u201cSeveral re-tries resulted in same indications as well as a retry after a power cycle; all other results were nominal. Engineering evaluation is in-work; additional troubleshooting to follow.<\/p>\n\u201cWork continues on the path to ET door functional. Challenges with the LH inboard thermal barrier and other conflicting work has caused the functional test to be rescheduled for early next week.\u201d<\/p>\n
Otherwise, all is going to plan, with the flow continuing to track preparations for Discovery\u2019s arrival next month via the mating of ET-135 and the SRBs in the VAB\u2019s High Bay 3 (HB3) \u2013 pending a mate review that will take place on Friday.<\/p>\n
\u201cS0003 ET\/SRB mate preps are continuing. Shims, FWD Sep Bolt and Strut Bolt preps are complete,\u201d added NTD status on the build-up of the boosters in HB3. \u201cLeft Forward segment mate is complete. Right and Left Forward Assemblies are mated, FWD Skirt Closeouts are in work.\u201d<\/p>\n
![\"A2\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/01\/A214.jpg\" "\\"A2\\"")
Over in the Checkout Cell (HB-4E), ET-135 is near completion with several routine \u201cshakedown\u201d inspections, in preparation with its lift over to the awaiting boosters for mating. This process also includes the pull tests that take place on the tanks, following a couple of incidents with foam loss from the intertank region during ascent.<\/p>\n\u201cET-135: Intertank Foam Adhesion Testing; Preps and foam application are complete. Trim is in work, \u201ccontinued the NTD processing flow report.<\/p>\n
\u201cShakedown and Receiving Inspections; Discrepancies are continuing to be worked noninterference \u2013 basis to processing. No major issues to report. AFT Hard-point closeout; Foam application is complete. Trim operations will in work.<\/p>\n
\u201cHelium Inject Box closeout; Conathane\/foam application is complete. Trim is in work. LO2\/LH2 transfer preps in work.\u201d<\/p>\n
MAF Procedures For IFR Checks:<\/p>\n
![\"A6\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/01\/A63.jpg\" "\\"A6\\"")
Foam loss \u2013 albeit minor by way of threat to the orbiter\u2019s Thermal Protection System (TPS) \u2013 from the intertank is one of two recent areas of evaluation, with incidents of liberations from the LO2 Ice Frost Ramps (IFRs) also recorded during STS-120, STS-125 (see left) and STS-127.<\/p>\nWhile foam loss from the LH2 IFRs further down the tank have been all-but successfully mitigated via modifications, the LO2 IFRs liberations kick-started new checks via an array of techniques that include X-ray, Terahertz scans and even the new observational tool of having a minicam ride up front on the flight deck in order to film liberations as they occur. This camera debuted on STS-129, but did not capture any events of interest.<\/p>\n
The likely cause of the liberations on recent flights is believed to be associated with voids in the foam, which are affected by the dynamic pressure, heating and flight environment during ascent, which can ultimately lead to minor liberations. Finding voids ahead of launch is the key mitigation approach undertaken by ET engineers.<\/p>\n
Known as Non Destructive Evaluations (NDE), the Program Requirements Control Board (PRCB) outlined increased testing to take place even before the tank arrives at the Kennedy Space Center (KSC), allowing for a full scan of the ramps at MAF \u2013 thus allowing for any repair work to take place ahead of shipping.<\/p>\n
![\"A4\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/01\/A413.jpg\" "\\"A4\\"")
\u201cET\/MAF expanded their NDE Process to include prioritized LO2 IFR Ramps. Added capability in Bldg 420 (at MAF) includes Backscatter and Terahertz techniques,\u201d noted the PRCB presentation, available on L2. \u201cNDE is performed prior to ET ship with minimal impact to process or schedule.\u201d<\/p>\nIn the unlikely event a repair is required on one of the ramps, the option remains to ship the tank on schedule and carry out the repairs at KSC \u2013 with the focus on the initial goal of finding the voids and evaluating if a repair is required.<\/p>\n
\u201cSome risk that if repair is required, it may have to be performed at KSC. Flight history suggest a Low likelihood of having a large void in the foam,\u201d added the presentation. \u201cProbability of performing a repair for predicted divot near 0.01lbm is low.\u201d<\/p>\n
MAF already had the capability to check for voids on the LH2 ramps and some LO2 ramps. The increased testing on the entire set of LO2 ramps was initially restricted by a lack of access due to their locations on the tank.<\/p>\n
\u201cET has done an outstanding job in implementing NDE for all critical IFRs. ET was already doing NDE on the Hydrogen (LH2) ramps and performing NDE on the more readily accessible LO2 IFRs. In their history of NDE they have never found void indications of the size believed necessary to produce suspect divots as single (foam) losses. But that does not mean it could not happen.\u201d<\/p>\n
![\"A5\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/01\/A56.jpg\" "\\"A5\\"")
Upon finding a void, evaluations will take place on its size \u2013 which will be the trigger for either informing the Space Shuttle Program (SSP) management for direction, or carrying out a repair.<\/p>\n\u201cET performs NDE on all IFRs: Any NDE voids with a predicted divot of 0.02lbm or larger \u2013 will be automatically repaired by ET (ET will advise is repair is not recommended),\u201d the presentation noted. \u201cFor any NDE voids with a predicted divot size of 0.01lbm or larger: ET will notify SSP for Review, will review with ET and make recommendation to (management boards) as required.<\/p>\n
\u201cDecision on whether to repair voids above the screening mass will depend on multiple factors: Actual Location and Size of indication (ET is conservatively combining smaller adjacent voids together and reporting as a single large void). Reliability of indication and history of predictions. Repair option and access to perform the particular repair.\u201d<\/p>\n
The LO2 IFRs and the Intertank evaluations mark what is likely to be the final two areas of the tank that require this additional mitigation work, as the Shuttle Program continue to enjoy what has been a run of extremely \u201cclean\u201d tanks following ascent.<\/p>\n
The amount of work that has been carried out on reducing foam liberations from the tanks since STS-107 has been nothing short of staggering, but it has reaped its rewards via the improved safety of the overall vehicle \u2013 even if bodies such as the Aerospace Safety Advisory Panel (ASAP) continue to fail in properly acknowledging those huge strides.<\/p>\n
L2 members<\/em><\/em>: Documentation \u2013 from which the above article has quoted snippets \u2013 is available in full in the related L2 sections, now over 4000 gbs in size<\/em><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
With Endeavour enjoying a smooth flow on Pad 39A, preparations for Discovery\u2019s STS-131 mission in March are picking up the pace \u2013 with the milestone of External Tank (ET-135) mating with the twin Solid Rocket Boosters (SRBs) set to take place next Monday. Meanwhile, the Michoud Assembly Facility (MAF) in New Orleans has been handed […]<\/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":[9021,9184],"class_list":["post-40887","post","type-post","status-publish","format-standard","hentry","category-news","tag-et","tag-sts-131"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40887"}],"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=40887"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40887\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40887"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40887"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40887"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}