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The RSRM\u2019s first note in ATK\u2019s presentation to the SSP FRR pertained to \u201cpin traceably\u201d for the Right Hand (RH) RSRM forward skirt\/forward dome joint.<\/p>\n
\u201cLost lot-number traceability for three -09 pins in the RH forward skirt\/forward dome joint,\u201d notes the presentation \u2013 available for download on L2.<\/p>\n
All pins that are installed on the RH RSRM meet engineering requirements. Furthermore, the RSRM presentation notes early on that this issue is not a concern for flight safety.<\/p>\n
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![\"BS2\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/BS2.jpg\" "\\"BS2\\"")
Also, flight approval for this issue via a Level II waiver was accepted on August 6 with a final waiver passing a Change Request review on August 11.<\/p>\nThe issue is that all of the -09 pins currently installed on Discovery\u2019s RH RSRM (18 total) bear the physical lot number marking \u201cECL0008\u201d and their specific build records cannot be located.<\/p>\n
As such, \u201cLot number traceability was lost, but part numbers are correct,\u201d notes the RSRM FRR presentation.<\/p>\n
Justification for flight was reached specifically because the -09 pins were created from the -03 pins (which are the standard\/baselined flight pin) \u2014 thereby allowing engineers to verify the material properties of the -09 pins.<\/p>\n
\u201cEngineering requires -09 pins be made from -03 pins by grinding 0.01 inches off the diameters.\u201d During this process, however, the physical part numbers on the pins were changed.<\/p>\n
Furthermore, the diameters of the -09 pins were verified during their fabrication process from the -03 pins. Also, all remaining -09 pins bearing the physical lot number marking \u201cECL0008\u201d have been re-inspected and \u201cmeet dimensional requirements.\u201d<\/p>\n
As such, the -09 pins are safe to fly on STS-128\u2019s RH RSRM.<\/p>\n
![\"BS3\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/BS3.jpg\" "\\"BS3\\"")
The next issue discussed with the RSRMs was the replacement of the V1247 fluorocarbon O-rings with V1288 O-rings in the nozzle-to-case joint.<\/p>\n\u201cV1288 was developed to improve resiliency with no degradation to other performance characteristics and fly with higher margins,\u201d notes the presentation.<\/p>\n
Resiliency testing of the new O-ring showed similar performance under squeeze and temperature conditions as well as a \u201cHigh temperature sealing capability equivalent to V1247.\u201d<\/p>\n
Furthermore, the erosion and ablation tests of the new O-ring revealed a significant improvement (by a factor of two) from the previous model, as did numerous static and in-flight (STS-122 and STS-125) tests in both the field joints and nozzle-to-case joints.<\/p>\n
The third and final topic discussed in the RSRM presentation pertained to the removal of an inactive Stiffener Stub.<\/p>\n
![\"BS4\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/BS4.jpg\" "\\"BS4\\"")
\u201cMachine off the forward-most (inactive) stiffener stub to eliminate a high maintenance, non-functional design feature,\u201d notes the presentation.<\/p>\nNon-Destructive Evaluations (NDE) and proof testing were performed prior to machining off the unnecessary component, after which extensive inspection was required to verify engineering characteristics in the high-stress area.<\/p>\n
Analysis shows the machined area will see temperatures during launch and SRB entry\/splashdown of 370 degrees F \u2013 which is well within the 500 degrees F limit.<\/p>\n
Furthermore, the removal of this stiffener stub \u201celiminates four debris liberation\/debris impact causes.\u201d<\/p>\n
Solid Rocket Boosters:<\/p>\n
Additionally, the SRB presentation to the SSP FRR documented two areas of concern identified after Endeavour\u2019s STS-127 mission last month and after STS-128\u2019s Shuttle Interface Test in the VAB earlier this month.<\/p>\n
![\"BS5\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/BS5.jpg\" "\\"BS5\\"")
The first issue discussed was the missing Marshall Convergent Coating (MCC-1) on both of STS-127\u2019s BI-138 aft skirts.<\/p>\nThe main reason for concern with this missing coating is that it is classed as a potential debris hazard to the Shuttle Vehicle during launch \u2013 mainly because MCC-1 is not an accepted debris and a Risk Assessment Mass analysis has not been performed on this area of the vehicle.<\/p>\n
However, a review of the MCC-1 spray operation has yielded a potential root cause of this issue.<\/p>\n
\u201cBI-138 aft skirts experienced interrupts during MCC-1 spray,\u201d notes the SRB FRR presentation.<\/p>\n
Standard re-spray operations with \u201crecovery error overlaps\u201d were used to correct the interruptions to the original sprays.<\/p>\n
In total, 10 SRB structures experienced interruptions in their MCC-1 sprays \u2013 the first of which flew on STS-117 in June 2007.<\/p>\n
Eight of these 10 (including BI-138 on STS-127) have flown with no MCC-1 coating loss noted during post-flight inspections.<\/p>\n
To date, analyses and inspection suggests the MCC-1 liberation event on STS-127 was limited to the overlap area of the sprays.<\/p>\n
All areas on BI-139 (the flight set for STS-128) have passed the 50 psi minimum requirement for pull tests and even exceeded the upper limit of the gage (204 psi).<\/p>\n
As such, the issue is not considered a hazard to Discovery and STS-128.<\/p>\n
![\"BS6\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/08\/BS6.jpg\" "\\"BS6\\"")
The final topic associated with the SRBs for STS-128 is the \u201cSuspect reverse rotation of LH tilt hydraulic pump and APU due to check valve failure during Shuttle Interface Test (SIT) ground hydraulics testing\u201d on the STS-128 stack.<\/p>\n\u201cNoted unusual \u2018air boat\u2019 sound from aft skirt shortly after ground hydraulics powered up for LH hydraulic leak check on STS-128\/Discovery,\u201d notes the SRB presentation.<\/p>\n
Multiple attempts to correct the issue were unsuccessful and the leak check was eventually aborted.<\/p>\n
Post-test inspection of the Trust Vector Control system revealed that the tilt pump was warm to the touch.<\/p>\n
The entire assembly (CVFA) was replaced at Pad-A following the rollout of Discovery. This was followed by multiple system retests and a hot fire test at the pad to certify the newly installed system for flight.<\/p>\n
Inspections of the removed CVFA revealed a failure of the check valve o-ring \u2014 which was classed as the only possible cause for the failure.<\/p>\n
Despite this finding, the investigation is still ongoing to ensure that nothing has been overlooked.<\/p>\n
Nevertheless, since the check valve is not used in-flight and all affected hardware has been replaced and all replaced hardware has been hot fired at the pad, STS-128 is safe to fly.<\/p>\n
With that, there are no RSRM or SRB constraints for Discovery and STS-128.<\/p>\n","protected":false},"excerpt":{"rendered":"
With STS-128 and Discovery officially cleared by the SOMD (Space Operations Mission Directorate) FRR for an opening launch attempt on Tuesday, August 25 at 1:36A.M. EDT, NASA\u2019s ongoing effort to ensure that all aspects of the Space Shuttle system are safe to fly was not dedicated just to the External Tank, as managers thoroughly reviewed […]<\/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":[3610,7806,9205],"class_list":["post-41019","post","type-post","status-publish","format-standard","hentry","category-news","tag-frr","tag-srb","tag-sts-128"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41019"}],"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=41019"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41019\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41019"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41019"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41019"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}