**The most comprehensive collection of Shuttle, Ares, Orion and ISS related presentations and mission documentation, plus expansive daily processing documentation and updates are <\/em>available to download on L2<\/em><\/font> **<\/em><\/font><\/p>\n STS-122 L2 Special NOW LIVE. **Click here for sample of L2 menu and content**<\/font><\/em><\/p>\n <\/font>**STS-122 Special: 12 MOD Flight Readiness Review (FRR) Presentations, Baselines and Mission Overviews. 17 Shuttle FRR Presentations. Payload Presentations and vast amounts of live, uploaded images and presentations. Installation Movies (several) \u2013 already 2000 megabytes strong** <\/font><\/em><\/p>\n **COMPLETE Section on ECO\/Feedthrough Connector issues and troubleshooting, graphical and data based \u2013 expansive.**<\/p>\n **LIVE updates on Atlantis STS-122 Troubleshooting Latest**<\/em><\/font><\/p>\n **LIVE updates on Discovery STS-124 Processing**<\/em><\/font><\/p>\n <\/u><\/em><\/p>\n Company News (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n<\/p>\n **LIVE news updates on Endeavour STS-123 Processing**<\/font><\/em><\/p>\n **Click here for FRR overview articles: Article 1 \u2013 Article 2** \u2013 Click *HERE* for all our articles on the STS-122 ECO\/Feedthrough Connector issue. Background:<\/u><\/em><\/p>\n Each SRB has two hydraulic gimbal servoactuators: one for rock and one for tilt. The servoactuators provide the force and control to gimbal the nozzle for thrust vector control. <\/p>\n Commands from the guidance system are transmitted to the ATVC drivers, which transmit signals proportional to the commands to each servoactuator of the main engines and SRBs. <\/p>\n Four independent flight control system channels and four ATVC channels control six main engine and four SRB ATVC drivers, with each driver controlling one hydraulic port on each main and SRB servoactuator.<\/p>\n The issue engineers are tasked with troubleshooting was originally found after the tanking test and subsequent ECO (Engine Cut Off) sensor troubleshooting, when the \u2018current monitor signal on ATVC 2, Right Rock Driver, exhibited erratic behavior when commanded to +4 degrees for approximately 20 minutes after power up\u2019 \u2013 resulting in an Interim Problem Report (IPR). The issue did not recur after several hours of operation. <\/p>\n \u2018Ambiguous whether the problem is the current monitor signal, the FA MDM, or the driver output from the ATVC being reflected in the monitor,\u2019 noted a report compiled on Friday. \u2018Wiring faults cannot be ruled out.\u2019<\/p>\n Troubleshoot Plan:<\/u><\/em> <\/p>\n Since the issue was spotted, engineers have struggled to isolate the fault, leading to the problem becoming an undesired Unexplained Anomaly (UA). <\/p>\n \u2018ATVC was instrumented per previous plan in an attempt to isolate the fault. Fault did not repeat. Further attempts to date have been unsuccessful,\u2019 added the presentation \u2013 although it has been rounded down to five specific areas, which includes wiring.<\/p>\n \u2018With no repetition of the fault, and little time to troubleshoot, the situation is a UA. Traditional UA practice would R&R (Remove and Replace) the ATVC and any other affected components (i.e., wiring) to assure that no parts remain that could have caused the fault.\u2019<\/p>\n However, to support a February 2nd launch date \u2013 the official NET (No Earlier Than) target, according to USA, NASA and Lockheed Martin schedules in relation to the completion of ET-125 troubleshooting \u2013 the replacement of the ATVC R&R work would need to be completed by Sunday. <\/p>\n \u2018In order to support a 2\/2 launch date, this activity would need to be complete by Sunday 1\/6 in order to provide time for hydraulics \u2013 on retest and nominal completion of Hydraulics close-out while ECO sensor wiring operations are underway,\u2019 added the presentation.<\/p>\n This option was one of three presented to shuttle managers on Friday, with R&R holding its own problems, mainly due to time constriants.<\/p>\n \u2018Time constrained \u2013 no opportunities to complete more intensive inspection or testing that might reveal more about the nature of the fault. No way to verify problem is solved unless it can be replicated at the depot \u2013 which will be time consuming without further characterization of the problem and relatively easy repetition,\u2019 noted the \u2018cons\u2019 on option 1.<\/p>\n \n<\/ol>\n <\/dir><\/ol>\n \u2018Risk buy-down is negligible if anomaly does not repeat more frequently or after the unit has been powered up nominally for launch.\u2019<\/p>\n Option 2 \u2013 which involved more extensive troubleshooting at the pad \u2013 would have led to an additional delay to the target launch date for STS-122, by up to 10 days (from Feb 2). Option 3 was to fly \u2018as-is\u2019 \u2013 although this was shot down by dissenting opinion.<\/p>\n A split opinion on flying \u2018as-is\u2019 \u2013 as opposed to the other available options \u2013 can be understood via associated documentation, which shows the system has redundancy and does not breach LCC (Launch Commit Criteria) rules.<\/p>\n \u2018Flight controls are quad redundant and two fault tolerant. Design philosophy oriented towards compensating for random failures in avionics and wiring (not effective for rapid sequential, simultaneous, or common-mode failures). <\/p>\n \n<\/ol>\n \u2018Right Rock signal required for 120 seconds after SRB ignition; ATVC not flight critical after MECO. Response of the system is identical for any random part failure (which can occur at any time), or repetition of a known-but-rare anomaly.<\/p>\n \u2018No LCC violations are associated with this fault unless the secondary delta pressure exceeds the LCC limit of around 237 psid after the slew test (BTVC-11) or there is a secondary delta pressure exceedance of 2200 psid that causes a channel to be bypassed (BTVC-12) at any time between T-21 and T-10 seconds.<\/p>\n \n<\/ol>\n \u2018Neither of these faults are likely with the observed anomaly \u2013 the command is around 1 degree during the slew test and zero thereafter. There is no indication that the fault causes erratic output without a command input.<\/p>\n \n<\/ol>\n \u2018If problem is thermal-related, ATVC will have been on for at least 6 hours before T-0 allowing time to reach thermal equilibrium.\u2019 <\/p>\n A spare ATVC unit is already at the pad, allowing engineers to carrying out the R&R without delay. **STARLIGHT: NEW STS-117 MISSION REVIEW MUSIC VIDEO** \u2013 STS-118 and STS-120 Mission review video also available.<\/font><\/em><\/font> <\/em><\/font><\/p>\n **ROCK YOU LIKE A HURRICANE: STS-117 MISSION REVIEW MUSIC VIDEO \u2013 AS SEEN BY THE STS-117 CREW!!**<\/font> -. While engineers continue to move forward with preparations for the installation of replacement external LH2 Feed-through connector hardware on ET-125, another issue may overlap the tank repair schedule. The problem relates to the ATVC (Ascent Thrust Vector Control) \u2013 specific to the commanding of the Right Solid Rocket Booster (SRB) Rock Actuator. The unit will […]<\/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":[],"class_list":["post-41512","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41512"}],"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=41512"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41512\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41512"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41512"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41512"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/em><\/font>L2: STS-122 to STS-127 documentation already available.<\/em><\/font><\/p>\n
<\/u><\/em><\/p>\nThe space shuttle ascent thrust vector control (ATVC) portion of the flight control system directs the thrust of the three SSMEs and the two SRB nozzles to control attitude and trajectory during lift-off and ascent. <\/p>\n
**Ride home through the fire, sparks and plasma of re-entry with Atlantis, Discovery and Endeavour. FIVE Stunning high quality 2hr, 355-400mb Camcorder and HUD videos \u2013 from payload bay closure \u2013 through re-entry with an astronaut held camcorder video \u2013 to post landing \u2013 several more videos showing landing from 90,000 ft also available and HUD videos from STA landings. Now includes HALO II Re-entry video, and re-entry videos from Gemini and Apollo (converted from 8mm)**<\/em><\/font><\/p>\n
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<\/em>L2 members<\/em><\/font>: All documentation \u2013 from which the above article has quoted snippets \u2013 is available in full in the related L2 sections, updated live.<\/em><\/p>\n
(Video section is FREE, but you need to sign up as a member of the forum to enter the video section of the site. We only use your e-mail to send you your password. It will not be used for spam etc.)<\/em><\/font><\/em><\/font><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"