Status Report

Minutes for August 7, 2001 EVA AIT

By SpaceRef Editor
August 7, 2001
Filed under , ,

To: Distribution

From: XA/Nancy J. Patrick

Subject: Minutes for August 7, 2001 EVA AIT

The EVA AIT met at the Johnson Space Center on August 7, 2001. Boeing/Gary Peters and XA/Nancy Patrick co-chaired the meeting. Representatives from CB/Flight Crew Operations, XA/EVA Project Office, NC/Flight Systems Safety and Mission Assurance, EA4/Systems Engineering, EC5/EVA & Spacesuit Systems Engineering, Lockheed-Martin, and Boeing-Houston (EVA, L&M, Struc & Mech, and Safety) were present. MOD did not attend. Representatives from the Kennedy Space Center, Marshall Space Flight Center and Boeing Development Centers supported by telecon. Copies of presentations can be obtained from XA/Bill Rollins, Building 1, room 661, (281) 483-1416.

1. Introduction/AI Review Boeing/Dave Read

XA/Nancy Patrick

The Following Decision Packages were distributed for review August 21:

PG1-S1/P1-EV&CS-DAP01-01: S1/P1 CETA Fastener Torque Exceptions

PG1-S1/P1-EV&CS-DAP01-02: EVA External Limit Load Exception — Bolt lock assembly

The Following Decision Packages were dispositioned (distributed July 24, 2001):

NCR-EVA-CID-002: Circuit Isolation Device (CID) 7 and 8 switch shafts do not meet EVA kick loads requirement.

Decision: This NCR was approved.

Boeing Provided Tools list update

5/8 Status: No report

6/19 Status: Still working on updates at Canoga Park and Huntington Beach. Inputs will be reviewed again on July 24.

8/7 Status: Huntington Beach used older version for updates, reconciling the two.

Review the following for concurrence/issues (distributed June 19, 2001):

PG1-P3-2001-1: SARJ Launch Restraint and EVA Bolt Break Torque Requirement

7/3 Status: This PIDS exception was deferred until July 24. MOD requested additional time to consider the ramifications of deleting some of the break torque test requirements. Ms. Patrick asked PG1/Roger Larsen to review the exception with XA/Beth Stubbings and Ed Mohr in the next couple of weeks.

7/24 Status: MOD was concerned that no testing was to be done on the S3 bolts, they would be accepted by similarity to P3 design (some subset of P3 bolts is being tested). The contractor wants to minimize the number of cycles on launch restraint bolts because they’ve had some problems meeting their final torque requirements because the locking patch becomes worn with repeated cycling. The contractor explained that they have experienced out of spec (high) running torques during installation, and have had to cycle the bolts a number of times to meet the running torque requirements, however additional wear due to cycling results in concerns in meeting the final torque required to sustain launch loads. There is no major cost or schedule concern with conducting the same level of testing on the S3 bolts, however the contractor was trying to minimize testing wherever possible. The EVA AIT was concerned that we may miss some S3 problems because we did not test any of the bolts (e.g. if S3 bolts came from a different lot than P3 and there was some problem with manufacturing that lot).

The EVA AIT recommended the following:

  • Determine whether installation torques are being recorded for all bolts. If this information is available, that will give some insight into higher than expected torques that may indicate a concern. (Input provided by PG1/Roger Larsen 7/27)

  • Provide final closure rationale for the SARJ launch restraint bolt high torque and locking patch wear issue. The final issue resolution may affect our opinion on whether S3 bolt testing is required (PG1)

  • Determine whether there is significant savings by not testing the S3 bolts

The EVA AIT will address the status on August 7.

8/7 Status:

  • Mr. Larsen provided sample installation procedures that indicate bolt torques are recorded during installation.

  • No information was available on the locking patch wear issue and whether that affects the proposal to not test S3 bolts. Mr. Larsen reported that PG1/Bob Grimes and Roy Van Winkle are the leads for the issue, and he will request that they report their status on August 21.

  • Mr. Larsen reported that deleting the S3 bolts from required testing is a cost avoidance because 450 hours of procedure development and review work would be required to approve the 5 tests required. In addition, unique test configurations and rigging would be required (different from the P3 tests) to support the same hardware testing on S3.

The EVA AIT agreed that the final determination of whether to approve the exception will depend on the locking patch wear issue and whether that issue resolution recommends bolt/locking patch testing of more bolts on S3. Mr. Larsen agreed to request support from PG1 for the 8/21 EVA AIT

The Following Action Items were reviewed:

AI-578: This action remains open and will be addressed again on August 21. Ms. Jochim is consolidating comments from various people and needed the additional time to do so.

AI-581: This action was closed for Huntington Beach and transferred to NT/Mirka Caro. It will be discussed again on August 21. Huntington Beach reported that the PRD option was brought up as a potential task during a Safety Review to help meet safety requirements for SSAS failures. The SRP suggested the PRD procedure as a possible option. Huntington Beach’s preliminary assessments show that up to 4 PRDs may be required to mate one of the truss segments. The schedule for completing the assessment has not been defined and in lieu of requirements, Huntington Beach is working toward completing the assessment in support of the 9A FOR. Ms. Patrick noted that incorporating a new requirement at that time will have adverse impacts to procedure development schedule, crew training schedule, flight manifesting and PRD inventory, and would probably not be feasible without a launch slip. Ms. Patrick requested that the SRP work with the launch package teams to document the new requirement in the FRD and IDRD so that it can be implemented on the requisite flights.

AI-594: This action remains open and will be addressed again on August 21. There was no report. After the EVA AIT, Mr. Looper reported that DX reviewed the worksite analysis and noted that the CETA cart probably cannot be used for the SSAS bolts, since the MT is located in a position required for S3/P3 installation that does not allow the CETA cart outboard of the MT. MOD is checking into whether the CETA cart can be in the outboard position and Ms. Patrick requested that Huntington Beach look into it as well.

AI-597: This action remains open and will be addressed again on August 21. Mr. Bonuan reported that the models they used for the analysis are consistent with the actual designs.

AI-599: This action remains open and will be addressed again on August 21. There was no report.

AI-617: This action remains open and will be addressed again on August 21. There was no report.

AI-619: This action remains open and will be addressed again on August 21. There was no report.

AI-622: This action was CLOSED. There is time available during a late September test if Huntington Beach determines the struts are not required for landing and therefore do not need to be on-orbit replaceable/interchangeable and other handling aids need to be assessed.

AI-623: This action was deferred prior to the EVA AIT and will be statused again on August 21. Huntington Beach requested deferring until September 4, however Ms. Patrick asked that they try to answer by August 21 to avoid test planning that would be required to meet a late September test, if required.

2. Thermal Equilibrium Requirements for ORU B-Hou/Scott Keepers


Mr. Keepers presented information indicating that under certain thermal conditions, some EVA actuated attachment mechanisms may not be fully operable until some period of thermal equilibrium is allowed. The concern is true for maintenance operations for four ORUs, which are the SPDA rails, TUS reel assembly, Ammonia Tank Assembly and HRS (TCS) radiators. The problems occur when the new ORU is at one end of the thermal range and the truss/attach site is at the other end. The problem is generally worst when the ORU is on the warm end of the range and the attach site is on the cold end of the range. The worst case dwell time required is as follows:

SPDA: 1 hour

TUS reel assembly: 10 hours

ATA: 8 hours and for the

HRS Radiator: 5 hours

Mr. Keepers proposed several workarounds for incorporating the dwell time into the ORU changeout scenarios. In all cases, the ORU can be at least partially secured by some means other than an EVA crewmember holding them. The EVA AIT discussed the changeout scenarios for each of the ORUs to determine whether there are any issues with the suggested workarounds

You can attach the SPDA Utility rails by the first two of the 11 bolts in the worst-case thermal disparity. Mr. Keepers suggested that the first two bolts be installed, then the crew should perform other SPDA rail changeout tasks (e.g. mating connectors into the rails) and/or other EVA tasks while waiting for the rail come to thermal equilibrium with the truss. The EVA AIT questioned what kind of EVA and ISS loads the rails could withstand with only two of the connectors mated. If the SPDA rail can survive EVA handling loads, it will probably be sufficient to perform other tasks with only the first two bolts installed.

The other items are all launched externally and the recommended resolution may have derived requirements for the ORU FSE design. Generically, it would be helpful if the FSE/carrier provided heater control for each individual ORU, so that individual ORUs can be managed thermally to minimize the dwell time required. This probably won’t be practical in all cases, however. The TUS reel assembly does not have a grapple fixture on it, and the FSE has not yet been designed so that the scenario for changeout is not fully understood. If the TUS reel assembly ORU can be removed from its carrier individually (i.e. the entire pallet of ORUs doesn’t come with the TUS reel assembly for robotic relocation), then it can be thermally conditioned prior to the EVA crewmember starting the installation task. If the TUS reel assembly cannot be removed individually, and the FSE does not provide individual ORU heater control, its not clear that the issue can be resolved with the existing hardware.

The ATA and Radiators require grapple bars for their remove and replace operations. (A side discussion ensued about whether both grapple bars are provided for the radiators, however after the EVA AIT Huntington Beach reported that both are included in LSARs and are provided by Huntington Beach). Therefore the EVA AIT proposed that these ORUs be held by the robot in a thermally favorable orientation to accomplish equilibrium prior to the start of EVA operations. The EVA AIT could not assess the orientation required and whether the robot can maintain that orientation for the time required. However if the robot system can provide means to accommodate the dwell time, the EVA scenarios are feasible. Since all of the ORUs except the SPDA require more dwell time than the duration of an EVA, some other method for securing them during dwell time will have to be provided anyway. More sorties may be required to accommodate the dwell time between EVA tasks than what would be required without the dwell time, however. Until the maintenance scenarios are better defined, the exact impact, if any, cannot be determined. Based on earlier maintenance discussions for the ATA and other similar ORUs, it’s likely that most of the scenarios involve one EVA to install grapple bars and remove the old ORUs, with the new ORU installation scheduled on a subsequent EVA anyway. Assuming the ORU can be place in a thermally favorable condition at the right time by the robot system, the EVA scenarios should be unaffected.

One additional item that the EVA AIT could not address, given the information currently available, was whether the resulting overall operations scenarios would be able to accommodate the dwell times required and still maintain the ORU within its thermal limitations. EVA is concerned that the dwell time may drive constraints on the maximum time before installing the ORU, as well as the minimum time. If the window between the two is too small, EVA may be overly constrained to accomplish the task within a very short time. For example if EVA is required to demate a TUS reel assembly from its carrier, and the assembly requires 10 hours to come to thermal equilibrium to allow installation, but the TSU reel goes out of its operating temperature range at 15 hours and must be installed by that time, EVA could not accomplish both the release and the installation tasks since the EVAs would be too close together.

The EVA AIT suggested that Mr. Keepers present this issue to the JOP to develop the integrated operations position. This forum will allow the robotics community and the ISS program to investigate the impacts to their operations based on the dwell times required.

Decisions and Conclusions:

The EVA AIT concluded that EVA can accommodate the dwell times presented assuming the following is correct:

  • The TUS reel assembly FSE allows fully robotic removal and relocation to a thermally favorable position to allow thermal equilibrium to be achieved prior to the start of EVA operations, or if the TUS reel FSE provides for individual ORU heater control. If neither of these are the case, the TUS reel assembly must be shown to meet loads requirements when in soft dock only configuration.

  • Thermal analysis will be done on the specific case when a changeout of one of these ORUs is required.

  • Thermal analysis must be done to ensure that the dwell times will fit into the overall operations scenarios without exceeding the allowable ORU unpowered limits.

3. Position of OTD on CETA Cart PG1/Melanie Hodges

Discuss concerns with the planned WIF location for stowing/operating the OTD on the CETA cart. Indicate which tasks may be affected by the planned location. NASA (EC, XA, DX) — indicate operational and engineering concerns with the planned CETA cart position and with re-locating CETA cart to another WIF should an operational interference arise. All — review existing ICD documentation that describes the requirements and limitations for where the OTD is stowed. Finally, discuss WIF labels and whether they: a) are common across all documentation and are clear and b) whether indications are required for whether a WIF is OTD compatible or not.

Ms. Hodges presented Huntington Beach issues with changes to and details of the CETA cart that have not yet been documented in the EVA Standard ICD. The first discrepancy is with changes to WIF labeling nomenclature, which was changed per crew input and is different from the nomenclature that Huntington Beach has used in already complete analysis. The second discrepancy is with use of WIF 5 for APFR based tasks, when WIF 5 has been designated as the only CETA cart WIF for the OTD.

The EVA AIT concluded that for the labeling inconsistency issue, Huntington Beach should not re-do worksite analysis. The EVA AIT requested that the CETA project conduct meetings with the operations community (MOD, Crew office) to determine whether it will be easier to revert to the labeling scheme that matches the Huntington Beach analysis, or accept that the Huntington Beach analysis will be incorrect with respect to WIF numbers and MOD will have to convert to the actual WIFs. Huntington Beach requested contract relief for verification of the WIFs in their reports. The EVA AIT agreed that XA will sign a letter that relieves them of this responsibility, and Boeing agreed to draft the letter to ensure it includes all the information required.

The EVA AIT then discussed the OTD WIF issue. Only WIF 5 on the CETA cart is certified for OTD loads (both operational and stowage). Huntington Beach has used WIF 5 for APFR based tasks in their verification analysis and would need to re-do analysis to confirm that the tasks can be completed using other WIFs. Further, Huntington Beach analyzed tasks with APFRs in other WIFs, but with the OTD still in WIFs other than WIF 5, and they are concerned that the OTD might interfere with the task if it has to be stowed in WIF 5. The EVA AIT discussed options for resolving this issue.

The EVA AIT concluded that no additional worksite analysis should be done at this time. The first approach will be to evaluate the other WIFs on the CETA cart to determine what kinds of operations are allowed with the OTD in those WIFs. It may also be possible to add another WIF to the CETA cart that could be made to handle OTD loads. Ms. Patrick requested that the CETA project investigate which of those two options are easier to accommodate. The fall-back option, if all else fails, would be to absorb the additional EVA overhead of relocating the OTD to one of the certified truss WIFs when WIF 5 is required (based on both Huntington Beach analysis and Crew and MOD evaluations) for APFR use for a task. This would only be required if we determine that using the other existing CETA cart WIFs for OTD storage is too much of a risk to the CETA cart.

Decision: The EVA AIT decided that no updated analysis is required from Huntington Beach to account for the CETA cart discrepancies (WIF labels and OTD stowage WIF). NASA will handle the discrepancies through either analysis, operations workarounds, or CETA cart modifications.

Action 624: Provide position on whether CETA cart WIFs should be labeled consistently with the Huntington Beach analysis (previous WIF labeling scheme) or whether MOD will convert the analysis WIF numbers to the proposed CETA cart labeling scheme.

Actionee: XA/Dale Roberts, EC5/Ben Greene, LMES/Bob Wilkes, DX32/Chris Looper, CB/Fernando Ramos

Due Date: September 4, 2001

Method for Closure: Report to EVA AIT

Action 625: Provide proposal for either analyzing CETA cart WIFs (except for WIF 5) for their load capabilities to determine whether the OTD can be temporarily stowed there, or whether a new WIF should be supplied that meets full OTD load requirements.

Actionee: XA/Dale Roberts, EC5/Ben Greene, LMES/Bob Wilkes

Due Date: September 4, 2001

Method for Closure: Report to EVA AIT

4. EVA ICD PIRN Status, ICD Issues XA/Greg LeStourgeon, Ahn Huynh, EC5/Gary Nickel

There was no presentation material for this topic. The EVA AIT chair signed the following PIRNs (approved by all Boeing parties and NASA).

– 79B: Torque Wrench (the EVA AIT chair thanked Mr. LeStourgeon and Mr. Schwarz for their efforts to resolve the issues with this PIRN)

– 83: IAPFR

– 84: MWS Modular Gimabal Assembly

– 85: Ball Stack Assembly

– 88: _ Turn Fastener and Latch Plate

– 89: EVA Connector Brush Assembly

– 90: Crew Lock EVA Bag

– 92D: CETA Rail Changes: (Signed out of board prior to EVA AIT)

– 93: ORU Tether Assembly

– 95: 5/32" Ball End Driver Assembly

There was no update to the following PIRNs still in work. (Previous status is included below). LMES was not present, and Boeing parties had not information. PIRNs 86 and 91 may be critical to upcoming FCA/PCAs, depending on their content.

– 86: TM Curved Handrail Assembly: Still in work within LMES, 50% complete, no ECD for submittal

– 91A: EVA Handrail Update: Provided Revision A to ICWG for upload, soon to be released for program review. Revision A pre-coordinated and should resolve issues with baseline version.

– 94: 3/16" Allen Driver: Still in work within LMES, on hold, no ECD for submittal

Mr. Nickel and Mr. Huynh discussed the PGT accuracy. They had reviewed the accuracy requirements in the EVA ICD (±
15% for torque settings up to an including 90 in-lbs and ±
10% for torque settings greater than 90 in-lbs) and did not have any information on where those accuracy numbers came from. The actual PGT accuracy is not currently quantified, however it is thought to close to ±
10% for torques higher than around 10ft-lbs (120 in-lbs). For very low torques, the accuracy varies but at best it is ±
20-25%. To achieve this accuracy at very low torques, a low RPM setting is required. Mr. Nickel reported that he had not reviewed all test data provided by Goddard for PGT acceptance (Mr. Nickel took responsibility for the PGT long after the tool was accepted by EC5), however he believed that the tool was only tested at ambient temperatures. The accuracy may be further affected by thermal extremes at vacuum. Ms. Patrick requested that Mr. Nickel and Mr. Huhyn report the problem to the EHB and develop a test and/or analysis plan to fully quantify the PGT’s accuracy. Once the accuracy is known, we can determine what further work is required. In addition, Ms. Patrick took an action to work with XA flight leads to review SSCN 1819 data from the flights developed so far, and determine if there are any bolts that require low torque and high accuracy. We will have to review those bolts for possible concerns with the installation procedures performed. Ms. Patrick thanked PG2/Scott Boller for recognizing the discrepancy and reporting it.

The EVA AIT then briefly discussed the issue raised with the Right Angle Drive. Canoga Park requested additional information on the operations constraints for the RAD documented in PIRN 74A in the EVA ICD. The constraint indicates that after 5 minutes of continuous use, the RAD must be allowed to cool for 5 minutes. Canoga Park questioned whether cooling the RAD (i.e. not operating it) at high environment temperatures is sufficient, or whether other operational constraints are required to account for high operating and "rest" periods. No one present knew whether the constraint takes into account high environmental temperatures, so further investigation is required. Ms. Patrick assigned an action to XA to address this. If the existing constraint takes into account ISS environments, no further action is required. If it doesn’t, a PIRN will have to be written to provide the appropriate constraint under all ISS conditions.

Since LMES was not present, the EVA AIT chair decided to defer the discussion on PIRNs that have not yet been submitted. Both Huntington Beach and Canoga Park indicated that depending on the content of these PIRNs (hardware changes/clarifications that they contain), they may be applicable to upcoming FCA/PCAs.

Action 626: Present PGT accuracy/inconsistency with ICD issue to EHB and solicit funding to test or analyze the PGT to determine its accuracy.

Actionee: XA/Ahn Huyhn, EC5/Gary Nickel

Due Date: August 21, 2001

Method for Closure: Report to EVA AIT

Action 627: Investigate flight operations to date and determine whether any bolts installed at low torques (less than 10 ft-lbs) required accuracy tighter than ±
20-25%. Use SSCN 1819 data provided.

Actionee: XA/Nancy Patrick

Due Date: August 21, 2001

Method for Closure: Report to EVA AIT

Action 628: Determine whether Right Angle Drive operations constraint in PIRN 74A (5 minutes off after 5 minutes continuous use) covers all ISS thermal environments, or whether additional constraints are required at high environment temperatures

Actionee: XA/Margaret McPhail

Due Date: August 21, 2001

Method for Closure: Report to EVA AIT

5. SSCN 5730/PIDS PG1-P3-400 Exception — PG1/Roger Larsen

Torque Value Changes since PIDS exception was approved

Mr. Larsen present the PIDS exception revision R1, which changes the maximum torque required to remove and install the UCCAS Capture Latch Assembly bolts. The previously approved PIDS exception (approved November 28, 2000) indicated the maximum torque required was 440 in-lbs. This value did not account for running torque. When the running torque is included the maximum torque required is 590 in-lbs. Ms. Patrick questioned whether this torque included thermal effects, and Mr. Larsen said that to the best of his knowledge, it did not.

Ms. Patrick requested that the PIDS exception be updated to include the maximum possible torque under worst-case thermal conditions. Ms. Patrick requested that the exception be re-submitted for EVA AIT review once it is updated. Ms. Patrick also requested that Boeing-Houston investigate how Boeing verifies their torque requirements. If thermal is not taken into account, bolts that exceed torque requirements may not be flagged for PIDS exceptions.

Action 629: Determine whether Boeing bolt torque verification takes into account thermal effects.

Actionee: B-Hou/Gary Peters

Due Date: August 21, 2001

Method for Closure: Report to EVA AIT

6. Proposed plan for Review of Worksite, Translation B-Hou/Mike Pagani, NT/Dan DaSilva

Path Protrusions non-compliances

There was no presentation material for this topic. Mr. Pagani reported that the Safety Review Panel is attempting to streamline the process for approving worksite and translation path protrusion non-compliance’s. According to Mr. Pagani, the SRP proposed that Boeing no longer submit NCRs for protrusion non-compliances. Instead, they proposed that only Boeing only submit PIDS exceptions. The SRP does not review PIDS exceptions, and proposes that the EVA AIT be the approving authority for the non-compliances. This only applies to protrusion requirements violations. The SRP would allow for an NCR to be submitted if the EVA AIT determined that the non-compliance results in a safety concern. This determination is left to the EVA AIT.

After polling the EVA AIT members present, the EVA AIT approved this streamlining proposal. Ms. Patrick later requested that the SRP document their recommendation in SRP minutes to confirm that the SRP also approves this proposal and delegates approval authority for protrusions non-compliances to the EVA AIT.

Decision: The EVA AIT agreed to allow only PIDS exceptions for worksite and translation path protrusion violations, and that the approval authority for violations would be with the EVA AIT.

Action 630: Request formal concurrence (memo or documented in SRP minutes) from the SRP that the EVA AIT is delegated authority to approve worksite and translation path protrusions and the NCRs are not required for violations to this requirement

Actionee: NT/Dan DaSilva, B-Hou/Mike Pagani

Due Date: August 21, 2001

Method for Closure: Report to EVA AIT

7. Upcoming Events/Future Agenda Review XA/Nancy Patrick, All

Ms. Patrick reviewed the preliminary EVA AIT agenda for August 21. Presenters were requested to confirm agenda topics by COB Thursday, August 16.

The following item was deferred until at least August 21:

TRRJ/FHRC Strut Issue PG1/Dan Pankratz, Dave Slader

DX32/Chris Looper, CA/Clayton Brown

Mr. Slader, Mr. Pankratz — report on whether the struts are required to meet landing loads, and therefore whether they are required to be on-orbit installable. Report on status of changes to make them on-orbit installable. Mr. Looper and Mr. Brown — report on when an NBL test of TRRJ change-out without the struts can be performed. Report on whether a test is necessary and recommended, and whether or not it appears adequate handling aids are available without the struts. Report on evaluation of existing bolts and whether they are acceptable for nominal EVA installation of the struts.

Decision Required: EVA AIT recommendation on forward work plan

Required Attendees: XA, Boeing-Houston, DX32, CB, NC, OB, OC, KSC/SSHIO, PG1, SLP,

Action Item Closure: AI-622, 623

SpaceRef staff editor.