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\u201cOV-103 \/ SRB BI-144 \/ RSRM 112 \/ ET-137 (Pad-A): The STS-133 S0007 Launch Countdown is underway and proceeding nominally along the timeline. Call to stations was completed on Sunday at 1330 hrs and the countdown clock picked up and began counting at 1400 hrs,\u201d noted the latest NASA Test Director (NTD) processing report (L2).<\/p>\n
\u201cAvionics configuration and checkout completed on Sunday. Preparations for PRSD load completed this morning (Monday) at 0500L. The vehicle and pad were configured for remote operations in preparation for orbiter, SRB (Solid Rocket Booster) PIC tests and PRSD load which is scheduled to begin shortly.\u201d<\/p>\n
PRSD loading began at 11:30 local on Monday, continuing through the first shift with the pad re-opening at approximately 17:30 \u2013 followed by the planned PRSD LH2 offload. Preparations were also carried out on the External Tank, ahead of Wednesday morning\u2019s tanking operations.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A3.jpg\" "\\"A3\\"")
The NTD also officially cleared two of the recent Interim Problem Reports (IPRs) from Discovery\u2019s list of issues, following the successful resolution of troublesome Quick Disconnects (QDs), in order to allow the completion of the pressurization tasks on Discovery\u2019s Right OMS (Orbital Maneuvering System).<\/p>\n\u201cIPR-52 RH OMS GN2 QD 525 update: All work is complete and the problem was resolved over the weekend. Flight cap installation and door closeouts were worked on Sunday. Troubleshooting over the weekend removed and replaced the QD on Saturday with additional troubleshooting performed when the GN2 tank continued to vent. This issue was isolated to a GSE valve. The tank is now pressurized for flight,\u201d added the NTD.<\/p>\n
\u201cIPR-53 RH OMS GHe QD 515 update: This issue was also resolved with all troubleshooting and corrective measures completing prior to S0007 CTS (Call To Stations). The QD was successfully removed and replaced on Saturday with flight pressurization finishing early on Sunday morning. Mass specs were also worked on Sunday morning with no discrepancies.\u201d<\/p>\n
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Two additional IPRs have been listed by the NTD \u2013 both minor and hold no impact to the flow \u2013 the latter of which was noted later on Monday, relating to a \u201cprimary panel dome and handrail\u201d which will require changing out late on Monday. IPR-54, meanwhile, related to a display issue on an event timer, which was in the process of being cleared at the time of Monday\u2019s NTD report. <\/p>\n
STS-133 Specific Articles: http:\/\/www.nasaspaceflight.com\/tag\/sts-133\/<\/p>\n
\u201cIPR-54: Picked up IPR against Forward Event Timer, 10th digit top left is out. T\/S (Troubleshooting) plan is to look at Fault Light documentation. Constraint is S0007.200 15-507. T\/S reveals Event Timer operating nominally with one segment out. (Engineering) recommends going MR (Material Review) to fly as-is and the test team is in concurrence. Will verify the Commander has no issues with flying as-is when the crew wakes up.\u201d<\/p>\n
SSMEs Ready To Fly:<\/p>\n
On Tuesday, the Space Shuttle Main Engines (SSMEs) will undergo their final preparations for launch \u2013 a processing task set to begin once the count is released from the 8 hour Built In Hold (BIH) at T-19 hours.<\/p>\n
UPDATE: (Task was on hold due to IPR-58 relating to Main Engine Controller (MEC) issue. Engineering Review Board (ERB) discussing \u2013 and cleared after recycling \u2013 before once again showing problems. New article pending.)<\/p>\n
As per usual, the three workhorses on Discovery\u2019s aft are expected to perform as advertised during ascent, with Flight Readiness Review documentation (over 50 presentations, available on L2) overviewing their status.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A319.jpg\" "\\"A319\\"")
All three of Discovery\u2019s SSMEs last flew with Atlantis during STS-129, although in different positions \u2013 after they required removing and re-installing in different positions, in order to allow a changeout of ME-1\u2019s Low Pressure Oxidizer Turbo Pump (LPOTP) early in the flow.<\/p>\nFor STS-133, Main Engine 1 (ME-1) is serial number 2044, ME-2 is 2048 and ME-3 is 2058. All their related hardware is the same as that which flew with Atlantis, bar a couple of elements, such as a new nozzle for ME-1.<\/p>\n
As is usual for the FRR process, previous flight experience and previous In Flight Anomalies (IFAs) are brought to the table for discussion.<\/p>\n
These included a one page review regarding IFAs as far back as STS-130, such as \u201cNozzle 5014 Thermal Discoloration & Damage,\u201d and an \u201cAccelerometer Disqualification\u201d issue on STS-131, all of which were minor and classed as \u201cclosed\u201d.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A4.jpg\" "\\"A4\\"")
The last flight \u2013 STS-132 \u2013 was the main subject of the FRR\u2019s deliberations, which concentrated on one of Atlantis\u2019 IFAs, relating to Nozzle 5007\u2019s Flow Recirculation Inhibitor (FRI), which was seen to be frayed in an \u201carea of higher gap and negative protrusion\u201d at the top of the nozzle.<\/p>\n\u201cBackground: FRI is used to reduce hot-gas flow and seal bluing in area of MCC\/nozzle G15 joint. Bellows seal prevents leakage to aft compartment. Fraying identified during standard post flight inspections,\u201d noted the Agency FRR presentation for the SSMEs.<\/p>\n
\u201cNozzle demated from MCC (Main Combustion Chamber). No bellows seal discoloration. Materials evaluation of FRI showed broken fibers, no indication of overheating or melting.\u201d<\/p>\n
The documentation continued by noting the history of this specific area of the engine, along with how improvements have continually been made over the near-30 years they have flown with the Space Shuttle.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A5.jpg\" "\\"A5\\"")
\u201cOriginal joint configuration had very small gap between MCC aft tip and nozzle tubes. No seal discoloration in the first 25 flights (no FRI used),\u201d added the presentation. \u201cRe-occurring issues with MCC and nozzle tube contact\/damage (led to) gap between MCC and nozzle increased to mitigate MCC damage.<\/p>\n\u201cAfter STS-26R, an overheated and cracked bellows seal was found (no FRI used). Analysis and testing defined influence of cavity entrance geometry on hot-gas recirculation into bellows seal cavity. Crown leakage also identified as a contributor to recirculation. FRI introduced to inhibit recirculation flow.<\/p>\n
\u201cFirst flight of FRI was STS-33R. FRI appeared to reduce, but not eliminate recirculation. Thickness of FRI later increased to improve effectiveness.\u201d<\/p>\n
Also referenced was the complex testing and analysis via Computational Fluid Dynamics (CFD) models, in order to simulate circumferential recirculation in bellows seal cavity, with the results noting the Nozzle\/MCC gap and nozzle tube protrusion cause hot gas recirculation, leading to the introduction of the FRI material.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A6.jpg\" "\\"A6\\"")
\u201cFRI developed to reduce hot gas flow to the G15 seal. (Made from) Ceramic fiber rope (which) withstands high temperatures.<\/p>\n\u201c(It is) pliable (and) provides a flow resistance to reduce circumferential circulation in the G15 cavity. Installed in 4 sections (2 long and 2 short). Long sections clocked in high protrusion areas,\u201d the presentation continued.<\/p>\n
\u201cStandard FRI (was used between) 1988 to 1995. Seal bluing on units with large gaps (was noticed, leading to) enhanced FRI (being) developed. Contains approximately 5 times more batting than standard FRI. Blued seals occurred less frequently. Always associated with high gap and protrusion and\/or leakage.\u201d<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A451.jpg\" "\\"A451\\"")
The FRR also looked at recent flight history, such as the numerous \u2013 yet tiny \u2013 nozzle leaks suffered on STS-128\u2019s launch (originally seen during STS-127), cited as a contributor to a weakened\/shifted FRI, although this caused \u201cno damage\/effect on (the G15) seal,\u201d thus aiding the subsequent flight rationale for both STS-133 and STS-134.<\/p>\n\u201cRationale for flight: Frayed FRI did not affect G15 seal during STS-132. Significant hot fire experience without FRI. Dominant influences in seal bluing are gap\/protrusion\/leakage. STS-133 and STS-134 units have gap and protrusion within acceptable limits per hot-fire experience.<\/p>\n
\u201cSTS-133 and STS-134 have no significant leakage near G15 (seal). STS-133 and STS-134 nozzles have no history of seal bluing.\u201d<\/p>\n
The relevance to STS-134 is noted due to Endeavour holding the role of Discovery\u2019s LON (Launch On Need) vehicle. Managers always aim to be confident of clearing any potential issues on all future flights, in order to avoid the potential nightmare scenario of a problematic launch during a rescue mission \u2013 as much as requiring a LON mission is highly unlikely.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/11\/A8.jpg\" "\\"A8\\"")
\u201cLaunch on Need Assessment: STS-134 Engines: ME-1 2059 ME-2 2061 ME-3 2057. Engines installed on Endeavour 27 \u2013 29 July 2010,\u201d added the presentation. \u201cEngines reviewed and ready to support contingency if required. Spare Engine set: ME-1 2045 ME-2 2060 ME-3 2047. Post-flight processing complete.<\/p>\n\u201cAll current flight and ground test anomalies have been evaluated with respect to impact on Flight Engines.\u201d<\/p>\n
Thanks to the historical and current confidence gained via the SSME FRR evaluations \u2013 which will prove to be priceless if, as currently expected, the SSMEs live on via the Heavy Lift Launch Vehicle (HLV) or Space Launch System (SLS) \u2013 managers polled to give their approval for the SSMEs to help Discovery make her final ascent into space.<\/p>\n
\u201cSSME Mission Readiness Assessment: The Discovery Main Engines are in a ready condition for STS-133.\u201d<\/p>\n
(Lead Image via HD QuVIS Video of SSME Start (L2). Graphics via L2. SSME installation image via NASA.gov)<\/p>\n","protected":false},"excerpt":{"rendered":"
Discovery is enjoying an issue-free S0007 (Launch Countdown), as engineers complete the loading of the orbiter\u2019s Power Reactant Storage and Distribution (PRSD) system. The veteran orbiter remains on track for an opening launch attempt on Wednesday, ahead of the ride uphill \u2013 to be aided by her three Space Shuttle Main Engines (SSMEs), which received […]<\/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":[3610,8116,9051],"class_list":["post-40615","post","type-post","status-publish","format-standard","hentry","category-news","tag-frr","tag-ssme","tag-sts-133"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40615"}],"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=40615"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40615\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40615"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40615"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40615"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}