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The latest processing issue was a concern relating to the SSME (Space Shuttle Main Engine) controllers, which \u2013 it was feared \u2013 were exposed to damaging X-rays, which were being taken as part of the FCV investigation.<\/p>\n
Space Shuttle
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\u201cSSME (Pratt & Whitney Rocketdyne\/KSC): There were some X-rays being taken of GH2 lines for FCV investigation. Learned they did not follow proper procedure to cover SSME controllers with lead blankets they normally use,\u201d added the latest Shuttle Stand-up\/Integration report on L2. \u201cAs a result, have submitted request to power up SSME controllers this morning for some troubleshooting.<\/p>\n
\u201cFirst thing want to do is a memory dump to see if memory is altered at all. Getting with Honeywell to see if are any other special tests or commands they could issue to controllers to make sure they were not injured by X-ray. This will all be documented on a PR (Problem Report).\u201d<\/p>\n
Those retests have since been carried out, with good results \u2013 thus clearing the concern the X-rays did impact on the engine controllers.<\/p>\n
\u201cX-rays performed in the aft which may have been done without adequate shielding protection for SSME Main Engine Controllers (SSMEC) Problem: Troubleshooting was performed to aid in the verification of the integrity of the SSMECs by comparing the EEPROM dumps with the compare tapes,\u201d added processing notes. \u201cAnalysis showed no errors.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/01\/a38.jpg\")
On the FCV issue itself, work is proceeding towards the removal of Discovery\u2019s three valves, ahead of their replacement with three spares, which suffered an incident via cleaning, though not deemed serious. This continues to be the number one item as managers move into the Flight Readiness Reviews (FRRs).<\/p>\n\u201cOn the FCVs, will work closely with (fabricator) Vacco as they resolve the staining after the dye penetrant and cleaning,\u201d noted United Space Alliance (USA) Logistics. \u201cHave a January 31 drop dead date from Ground Ops to support mission.<\/p>\n
\u201cWill work with Vacco to see if can authorize premium overtime or whatever can do to get back on track to support date. Are probably yellow now on delivery.\u201d<\/p>\n
The need for overtime to get the spares delivered to KSC on time is due to the noted incident with the cleaning of the valves, which has slowed down the timeline.<\/p>\n
\u201cOrbiter is slowing down on delivery of assets to KSC to install for STS-119 because of an incident that happened when cleaning dye penetrants from the poppets. Deionized water was used,\u201d added the stand-up. \u201cThis material is somewhat sensitive to oxidation, and the deionized water has to be dried off.<\/p>\n
\u201cThat process was not performed as it should have been, so there are some stains on the poppets, with the worst stains on the three spares they want to fly on STS-119. Believe have cleaning technique that will remove a small amount of material from poppet, but will be acceptable from a flow balance standpoint. Will do this over next couple of days.\u201d<\/p>\n
The main focus is on ensuring there is flight rationale with the spare valves, following the STS-126 incident, that does not rule out a problem that is risked on all such valves. Part of that flight rationale requires engineers to evaluate what could be the worst case scenario during ascent.<\/p>\n
Those risks, one which is understood to be a LOV\/C event (Loss Of Vehicle and Crew), need to be weighed against probability \u2013 which would be very low, as is the case the numerous LOV\/C events a shuttle risks during ascent.<\/p>\n
\u201cBeen looking at failure modes and scenarios, and when could get into trouble with possible venting on tank,\u201d added the JSC\u2019s Orbiter department. \u201cMost scenarios would require two failures, but some could cause problems. More work is to be done.<\/p>\n
\u201cAlso is work going on to understand if are environments present that can give high cycle count needed for the high cycle fatigue. Investigation indicates did have a high cycle heat failure. Team is scrubbing environment and doing some CFD modeling.<\/p>\n
\u201cHave been working on a technique called OJAY that allows them to look at oxide deposits on the fracture face. Have preliminary indication on the four different fracture surfaces (happened as crack progressed) of different amounts of oxide on each surface. This might suggest the fractures took place over more than one flight, progressing over time.<\/p>\n
\u201cThere are some potential problems with this technique, so have many experts looking over the data again. If they could show that this was the case, it would help give some rationale for flight. Flight rationale will be built on risk acceptance of a low failure rate, and for most failure modes, we can tolerate the results.<\/p>\n
\u201cLooked at spare poppets and say they look as good as new and are good to fly.\u201d<\/p>\n
JSC\u2019s Orbiter Project department are also involved, and held the Orbiter Project Office (OPO) FRR ahead of the main FRRs, classing the FCV issue as the one constraint to flight at present, due to the potential of a Critical One failure during ascent.<\/p>\n
\u201cWith the two process escapes this week, have told team to slow down. OPO FRR have one constraint for flight, FCVs. This story will continue to evolve as we get closer to flight.<\/p>\n
\u201cHad great support from MSFC (Marshall Space Flight Center) on understanding acoustic environment. Have the experts that work knife edge seal to see if this is an acoustic environment phenomenon. On flammability issue, everyone considers venting to be a Crit 1 failure mode.\u201d<\/p>\n
The topic will receive its biggest review at the SSP (Space Shuttle Program) FRR next week, which is held over two days, before heading to the Agency level FRR the following week \u2013 which sets the launch date. By then, managers have a better understanding on the schedule timeline, which will hopefully of concluded the replacement of the valves on Discovery.<\/p>\n
L2 members<\/em><\/em>: All 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":"
The giant S6 integrated truss segment is set to be installed into Discovery\u2019s payload bay over the weekend, as the shuttle continues to press through the opening stages of the S0009 pad flow. Meanwhile, the Flow Control Valve (FCV) issue has been classed as the only constraint to launch, as engineers work through flight rationale ahead […]<\/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":[9191,9123],"class_list":["post-41214","post","type-post","status-publish","format-standard","hentry","category-news","tag-fcv","tag-sts-119"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41214"}],"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=41214"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41214\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41214"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41214"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41214"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}