With the focus firmly placed on the repairs, inspections and required flight rationale for the LOX/Intertank flange stringers, hopes have being raised of a positive outcome by the end of the coming week. However, deputy Space Shuttle Program (SSP) LeRoy Cain dismissed internal rumors of schedule pressure to avoid a slip to next year, by noting the Program is adamant they won’t fly until they are ready.
With good leak checks on the Ground Umbilical Carrier Plate (GUCP) – which will be completing its required torque periods over the weekend – the cracks on Discovery’s External Tank (ET-137) will continue to be the main driver to returning the stack into a flight-ready configuration.
Some small issues were suffered during the preparation to install the two doublers into the vacated S6 and S7 locations, following the removal of the two stringers which both suffered from two cracks.
“ET LO2/IT stringer cracks: S6 and S7 doubler installation work continues. All the fasteners were installed. However, two bolts on S6 failed shanking measurements, and two bolts on S7 failed faying surface measurements,” noted the NASA Test Director (NTD) report (L2).
“The S6 fasteners will be Material Reviewed to use as is. For S7, there was a gap under the doubler and all 16 fasteners had to be drilled out, shims installed, and then the fasteners were reinstalled. Stringer end caps will be installed this morning.”
Under the guidance of engineers and technicians not only from the Kennedy Space Center (KSC), but also from the Michoud Assembly Facility (MAF), the two doublers were successfully installed without further incident. This was followed by the application of a conathane primer on Saturday, ahead of a four hour cure time – originally listed as a 16 hour process.
A large crane was also positioned at the pad to provide assistance in lifting the conex container hosting the foaming equipment up to the specially built environmental tent on the Fixed Service Structure (FSS).
With the milestones now being reached a day ahead of the pre-planned timeline, Saturday night saw the application of the BX-265 foam to cover the doublers and effectively begin ET-137’s transition towards a repaired tank. The BX foam began its 72 hour cure period at 8:30pm Eastern. The cured foam will then be trimmed and shaped early next week.
Also being carried out at the pad are the Non-Destructive Evaluations (NDE) on other areas of the flange on ET-137, with the aim to clear the tank from showing any other signs of cracks in its remaining stringers. NDE backscatter scans have been worked on +Y side of the tank, ahead of picking up with the LO2 flange scan on the -Y side.
So far, no indications of defects have been noticed on the initial 12 stringers which have received a closer inspection, raising hopes the original problem was localized to stringers S6 and S7.
“ET (LMSS/MAF) Looked with NDE at 12 of the stringers on the Panel 3 (+Y side) with no observations so far of any cracks. That activity will continue,” noted Lockheed Martin/ET on the latest Shuttle Standup/Integration report (L2), who pre-empted the potential of “having a good day” to get to the point of spraying the BX-265 foam on to the tank on Saturday.
“There has been a little change in the plans. The baseline schedule called for the BX spray closeout to be on Monday. (However,) if they have a good day with stinger installation and preps for the spray, hope to be able to spray it on Saturday. The Sprayers have been doing their demo sprays at MAF. They (have travelled to) KSC.
“They are trying to gain a couple of days on the spray activity. Once they get it to cure, Lockheed-Martin will come back in and trim up, and complete the trim and buyoffs in that Monday/Tuesday timeframe.”
Other work ongoing at the pad includes pre-emptive preparations for the return to a launch countdown (S0007) stance, although the timeline continues to be refined due to Friday’s decision to slip the NET (No Earlier Than) launch date to December 3.
“S1006, LH2 Dew Point/Conditioning, was successfully completed. ET camera checkout and adjust for the new launch window was performed. OMS/RCS (Orbital Manevering System/Reaction Control System) GHe QD (Quick Disconnect) R&R completed,” added the NTD on the current scheduled – subject to changes.
“Range Safety battery R&R is scheduled for Monday; requires ordnance to be disconnected and reconnected. S0071, Hyper/MPS (Main Propulsion System) Pressurization and Closeout, is scheduled for Tuesday. S0007.100 Launch Countdown preparations are in work.”
A large effort is being undertaken at several centers in order to build flight rationale for ET-137, again focusing on the cracked stringers. The first cracked stringer (S7) has already been sent back to MAF for a forensic investigation, with the Marshall Space Flight Center (MSFC) also conducting inspections on the fractography of the failure.
“At MAF and elsewhere in the system, the investigation analyses is underway to understand this failure and try to flush out the path forward and flight rationale. Stringer 7 has been back at MAF. Forensics is in work,” added Lockheed Martin on the Standup report.
“Some early tests are in work. Some additional samples are being prepped for more testing, and fracture facing was removed and sent to MSFC for fractography and detailed assessments. The S6 removed piece was received back at MAF this morning. It will likewise get into some forensic activities.”
The results of the ongoing investigation continue to be collated by centralized meetings, which opened with the joint Shuttle Engineering Review Board (SERB)/Systems Integration Control Board (SICB) last Tuesday – resulting in encouraging signs that there was a “path through the woods” on the required flight rationale.
“Held a Joint SERB/SICB on Tuesday. It went really well. Had really good discussion. Went through a lot of the background, looked at the root cause, the way that the intertank is built up. The team is really looking at all the things that they need to be looking at,” per the Chief Engineer notes (L2) at the Johnson Space Center (JSC).
“They talked about the metallurgy plan and the fractography plan, the structural analysis, the NDE underway at KSC, and the repair (adding the doublers and the BX spray). The flight rationale was discussed; there is a path through the woods but there is a lot of work ahead. The team is doing everything they need to do to get there. Even the broader community is asking a lot of good, right questions to ensure this thing is done right.”
This meeting was followed by Thursday’s Program Requirements Control Board (PRCB) meeting, which showed just how much work is going into the root cause and flight rationale, with numerous – and highly impressive – presentations on the GUCP, Intertank stringers and other associated STS-133 notes of interest. (All 10 presentations available on L2 – specific articles in work).
Meanwhile, Mr Cain used the Standup report to rally the troops, a usual and welcomed opportunity to internally communicate with the workforce on the thoughts of upper management within the SSP and NASA.
“There is a lot of work going on around the Program. The effort has been impressive, the attitude is outstanding. There is regular ongoing vehicle processing that is happening between, as is always necessary at the Pad. And of course, there is the work on the stringer,” noted Mr Cain.
“The repair work is well underway and the teams seem to have a very good handle on that, it is the standard repair, although being at the Pad presents some challenges. The team is going at a very measured pace and on a good path.”
Mr Cain also repeated the main challenge of acquiring flight rationale, intimating it is close, but that they will continue to work towards ensuring they are confident they have a satisfactory grasp on the data before they return Discovery into the next launch attempt.
“We have a large challenge in front of us with regards to developing our flight rationale. There is a lot of analytical work going on to determine the loads cases, which is very important in this discussion where the stringers are concerned. That work will potentially come to fruition over the weekend.
“There is a lot of work on the Pad load cases for the cryo loading as well, as well as the ascent environment, and the associated stresses where the stringers are concerned. There is foam and debris analytical work ongoing. We will work through the problem at a pace that is acceptable and comfortable to the team. We won’t fly until we are ready.”
STS-133 Specific Articles: http://www.nasaspaceflight.com/tag/sts-133/
Mr Cain also touched upon accusations of schedule pressure, something the SSP hate being intimated by either the media or via the workforce, given its association with some of the darkest days of the Program.
While none of the space flight media appear to have made such claims, sources note a rumor cited to “management” was making rounds, with the startling claim that if there wasn’t a resolution of ET-137 before the mission slipped into next year, the Shuttle program would end without any further flights.
While this site’s top level sources note such a claim is nonsense – and this site has never seen any evidence to support the notion of schedule pressure in its five years of reporting on the Program – it appears such rumblings have made it back to the SSP at JSC.
“There have been some (intimations), both inside and outside our immediate space community, that we may be operating and influenced by schedule pressure as we work through this problem. This is troubling,” noted Mr Cain, as he used the Standup to make a passionate and impressive rebuttal to such claims.
Ironically, Mr Cain wrote the notes just hours ahead of the slip from a November 30 NET to a December 3 to 7 launch window, in order to allow for additional time to build the flight rationale – which in turn backed up the points he was making.
“Our next launch period, as it is worked with our friends in the ISS Program, is the November 30 to December 6 period. If there is a way to make that launch period at the end of all of our work, where we have a very thoughtful and complete assessment of where we think we are as it relates to the risk associated with these anomalies, and we can do something within this launch period, then we will.
“If we can’t – then we won’t, and we are not going to do anything until we are ready to go fly safely. We have other launch periods, as we always do, that carry into December, January, and February. Our next best advertised launch period is the one we were planning to fly STS-134 in, so we have a lot of options where the schedule is concerned.
“The flights are not created equal, so we always have those discussions with the ISS Program, with the rest of the team, and the agency leadership. (I want to) reassure everyone that on a Program level we are very adamant about the fact that we will not fly until we are ready. No one is pressuring (me) to launch in this next period, and (SSP manager Mr John) Shannon will tell you the same thing.
“If folks are feeling that, they need to know this, because that is not the Program’s intent. You are encouraged to come forward and let them know if you feel that their actions are not matching their words and their very clear and sincere intentions.”
“The team is doing an outstanding job. And as usual, if we just get out of the way and let them tell us when they are ready to come talk to us and give us a status and updates we always do better. That is our intent here and is what we are trying to put into practice.
“Keep up the great work. It is appreciated more than you can know.”
(Further updates and articles will follow. Refer to live coverage threads linked above. L2 members refer to STS-133 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used, Lead: NASA.gov. Within the article: via L2 acquired PRCB presentations).