Status Report

Minutes for February 27, 2001 EVA AIT

By SpaceRef Editor
February 27, 2001
Filed under ,

The EVA AIT met at the Johnson Space Center on February 27, 2001. Boeing/Curt Carlton 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, DX32/EVA Systems/Mission Operations, OC/ISS Operations Office, OB/ISS Vehicle Office, Lockheed-Martin, Boeing-Houston (EVA and Safety), and Boeing-Canoga Park were present. Representatives from the Kennedy Space Center and Boeing Development Centers (Huntsville and Huntington Beach) 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/Lou Ramon

XA/Nancy Patrick

The Following Decision Packages were distributed for review March 13, 2001:

SSCN R-PCM-0473: Exception to EAS QDS M2, M7, M8, M9 and M10 EVA Gloved Hand Clearance

NCR-COL-ESA-0002/A: Safety NC, Sharp Edges (Columbus Module)

EETCS Radiator Accumulator "Cross Wiring" Issue

The Following Action Items were reviewed:

AI-511: This action remains open and will be addressed again on March 27. Ms. Patrick reported that she has not made any progress on the action.

AI-556: This action remains open and will be addressed again on March 13. The thermal analysis has been further delayed due to closer flight requirements.

AI-560: This action was CLOSED. Mr. Price reported that B-HB safety does in fact request worksite analysis for all EVA tasks required as ops controls to hazards. This closed the last remaining question associated with this action. During the discussion, Mr. Price reported that the only task that B-HB safety has requested for which no worksite analysis has been done is a contingency task using PRDs to cinch two truss segments together. Mr. Price reported that this task was requested by the SRP. No one present was aware of this task, and all were concerned that this task was being suggested by the SRP. Mr. Price and NC/John Foss agreed to look into the genesis of this task with their respective SRP representatives. The following action was assigned:

Action 581: Determine where the requirement arose for use of PRDs to mate truss segments in a contingency. Check with NASA and B-HB SRP representatives. Determine how "hard" the requirement is and whether it is based on some EVA input that the task is feasible

Actionee: PG1/Larry Price, NC5/John Foss

Due Date: March 27, 2001

Method for Closure: Report to EVA AIT

AI-570: This action was CLOSED. The tests were conducted with agreement from all participants on the procedure and configuration required. Results will be presented to the PG1 IRB for evaluation. The conclusion of all test participants was that the blankets, as currently designed, will interfere with ORU installation. See minutes below for additional information.

AI-572: This action was CLOSED. The tests were conducted with agreement from all participants on the procedure and configuration required. Results will be presented to the PG1 IRB for evaluation. The conclusion of all test participants was that the blankets, as currently designed, will interfere with ORU installation. See minutes below for additional information.

AI-573: This action remains open and will be addressed again on March 13. The test was complete and Mr. Pankratz reported that he intends to schedule the discussion at the IRB on March 12. Mr. Pankratz will report the results of the IRB on March 13 and the EVA AIT will determine at that time whether additional discussions with PG1 management are required.

AI-576: This action remains open and will be addressed again on March 27. Ms. DeLeon presented most of the worksite analysis information. The EVA AIT requested pictures for each bolt worksite and information about how the bolts are packaged for launch and transported to the worksite.

AI-577: This action remains open and will be addressed again on March 27. The Actionee was not available for the EVA AIT.

AI-578: This action remains open and will be addressed again on May 8. None of the actionees had made progress, and all agreed it is a low priority action.

AI-579: This action was CLOSED. Ms. Patrick reported that there are markings on the APFRs and OTDs that meet EVA requirements for font size and contrast. Its not clear that they are in a location that would be acceptable if unit identification is required on a regular basis, however it may be sufficient for only tracking anomalous units or slight configuration differences. MOD and the crew office will evaluate class 1 unit markings and request any additional markings at the EHB. (MOD and crew had requested additional markings based on review of class 3 units, which don’t have the same markings as the class 1 units)

2. EMU extended contact re-certification test results ES/Jay Leggett, LM/John Iovine

No EMU representatives were present to report the EMU re-certification status. This topic will be rescheduled to March 13.

Mr. Iovine reported that the variance in End-of-Life properties and Beginning-of-Life properties, the variance in how quickly EOL properties occur between different components, and the number of beta angle/attitude combinations available make it difficult to provide beta angle trends for thermal profiles. The PTCS thermal analysis completed for ISS components uses EOL properties to cover the worst-case thermal scenario.

Based on analysis completed to date, if the PTCS team provided a single beta angle constraint for when any part of the Lab exceeds the predicted EMU thermal limits for extended contact (-145ºF to +240ºF), it would be approximately |25º|. Mr. Iovine and Mr. Leggett explained that a small number of Lab MMOD shields violate the EMU limits at low beta angles, and that typically it is a short duration violation. The specific shields that violate the limits changes as the beta angle changes, but for most beta angles under |55º|, the predictions are that the temperature violation will be a short duration. Further, the "hot spot" will move from one shield to the next throughout the orbit, as the sun angle moves across the ISS during the orbit, so no individual shield exceeds the temperature range for very long. Mssrs. Iovine and Leggett recommended that flight/time specific analyses continue to be performed to identify problem areas prior to an EVA, rather than try to identify the specific conditions under which a component will exceed the EMU capability. The flight/time specific analysis will take into account only the conditions that apply to that particular time period, with a much smaller chance of identifying problems that have no easy operations workaround.

Significant discussion not included in the presentation material:

The EVA AIT discussed whether there is enough information available to conclude that the ISS can be assembled and maintained without severe operational impacts, given that surface temperatures can exceed EMU capabilities under most orbital conditions. The thermal team felt that while virtually any possible set of beta angle/attitude/configuration combinations will result in some surfaces exceeding EMU capabilities, the problem spots will be few at most orbital conditions, and will be short-lived. Their opinion was that there would be rare instances that could not be solved by briefly shading the component or waiting short periods of time until it is back within limits.

The EVA AIT then addressed how to provide enough useful information to the operations community to characterize the issue and provide guidance on when operations controlled would be necessary. It was obvious that simply relaying a beta angle cut-off for an element would not provide enough useful information, since virtually all pressurized elements would exceed the EMU capability at most beta angles. The EVA AIT briefly discussed providing a beta angle constraint for individual shields, however this would require significant work from the thermal community and the amount of information would probably be overwhelming and thus not useful either. The EVA AIT then suggested that it might be useful to provide an incident sun angle constraint for each type of component that will exceed the EMU capability. So far, the list of offending hardware consists of only the MMOD shields and unprotected electrical connectors. If a single incident sun angle limit can be provided for all MMOD shields, this might provide at least enough information for operations to have an intuitive feel for which shields/connectors will exceed the temperature limits, and when they will exceed them. Mr. Leggett agreed to look into whether it will be reasonable for the PTCS team to provide that information.

The EVA AIT agreed to discuss the situation further when more information regarding the EMU thermal re-certification effort is available

Action 582: Determine whether the ISS PTCS team can provide an incident sun angle at which MMOD shields and unprotected electrical connectors exceed predicted EMU thermal capabilities

Actionee: ES/Jay Leggett

Due Date: March 13, 2001

Method for Closure: Report to EVA AIT

3. Results of P1 PM-A and NTA Installation PG1/Dan Pankratz

The only presentation material for this topic was photos of the installation test activity.

Mr. Pankratz reported on the results of the PMA and NTA installation demonstrations on P1. With the blankets configured in a worst-case ground installation configuration, there were significant problems with blanket interference during ORU installation. The worst-case blanket configuration is considered to be a reasonable configuration, since it mimicked possible on-orbit effects for blanket ballooning. In fact the installation had to be halted at one point to avoid damaging the blanket. The NTA shroud interfered with the soft dock mechanism, guide rails and nut plate. Attempts to joggle the NTA into position around the interference points were unsuccessful. Joggling it around the soft dock and/or guide rails resulted in the interference with the nut plate. The PMA blanket experienced interferences with the NTA bracket, pins and then the soft dock. Photos and video recorded the problems experienced during the test and will be used to present the issue to the B-HB IRB.

The EVA AIT discussed whether there are any workarounds for the blanket interference. At the test, joggling the ORU around the interference points was considered, however the EVA AIT determined that this was not a feasible workaround. Joggling a large ORU in such a confined area would be difficult at best, and would completely ensure that the blanket would not catch on something and sustain damage. Additionally, the ORU installation angle was already very constrained to avoid surrounding structure, and an attempt to joggle it into place may result in bumping other structure. The EVA AIT concluded that hardware changes are required to ensure the ORUs can be installed. The hardware changes necessary could be as simple as adding Velcro to constrain the blankets in the potential interference points. It may be possible to wait until the replacement ORU is launched to change the blanket design, however that depends on whether you can be assured the existing blanket will be installable on the orbiter carrier required to transport the ORU back to earth.

Mr. Pankratz agreed to contact the B-HB IRB to schedule this topic at the next available time. Mr. Pankratz will attempt to present it to the March 12 IRB. Mr. Pankratz agreed to report the status and/or results of the IRB discussion at the March 13 EVA AIT.

Decision: The EVA AIT concluded that the NTA and PMA blanket design must be changed to ensure no interference during ORU installation.

Action Item Closure: AI-570, 572, were CLOSED. AI-573 remains open until the issue is resolved with the B-HB IRB.

4. MBS Battery ORU — EVA Handling and Installation MDR/Ben Yehudaiff

Mr. Yehdaiff presented information concerning a new ISS proposal to install a keep-alive battery on the MBS. The battery will support MBS components for a limited amount of time should the MT fail between utility ports or some other failure of the system prevents power to the MBS. A separate proposal, discussed at the February 13 EVA AIT, to attach an extension cable between the MBS and a utility port is an additional capability but does not replace the battery. (The battery sustains the components until the cable can be attached. The cable sustains the MBS until a repair can be performed — possibly not until a shuttle flight to supply the failed component). The battery has not yet been approved for implementation, and the program will not decide until later this year whether to fund it. The MBS has to be scarred to support the battery before a final decision on the battery is made, therefore CSA and MDR provide adequate provisions on the MBS now and that includes EVA evaluation of the task. CSA/MDR have provided preliminary worksite analysis, and a TIM was held in mid-February with EVA to evaluate the task.

Significant discussion not included in the presentation material:

The EVA AIT concurred with the EVA representatives to the TIM, that there are no certain issues with installing the battery, however the battery mass will be a concern that will require further evaluation. The battery may be up to 750lbs, and the handling required for this mass may be a problem, depending on the specific manipulations required. The EVA AIT concurred that NBL evaluation of the worksites and positioning, and Virtual Reality (VR) Lab evaluation of the mass handling are required to confirm the task feasibility. XA/Tara Jochim and DX32/John Ray agreed to coordinate the scheduling of both, and requested design data/drawings to develop the VR model. MDR requested as much evaluation as possible prior to release of the battery PDR data package, scheduled for March 29. Ms. Jochim and Mr. Ray will attempt to get the VR lab evaluation by that date, but the NBL evaluation will probably not be until May

5. SSAS Contingency Override Bolt Procedure Status PG1/Larry Price, Berta DeLeon

Ms. DeLeon presented an overview of the worksite analysis performed for the SSAS contingency bolt procedure. Ms. DeLeon has completed the preliminary analysis for attaching a single set of contingency bolts (2) for each attachment point. (Ms. DeLeon assumed 3 of 4 motorized bolts are fully engaged for each truss attachment, which allows using worksites on the new segment). With that assumption, WIF based worksites are available for every possible contingency bolt attachment (32 locations). Ms. DeLeon also provided for the previously reported optimum body positioning reported at a previous EVA AIT (one hand on the socket, the other on the torque wrench handle).

Significant discussion not included in the presentation material:

Ms. DeLeon reported that the input from the B-HB structures team was that the torque/tolerance required is 80 ft-lbs, ±10%. Ms. DeLeon did not know whether that was the absolute requirement for the tolerance or just what is known today based on the analysis. Several present surmised that this number may be based on the results of existing analysis that has not yet been formally reviewed by NASA. Further discussion of the torque tolerance required was deferred until March 27.

Ms. DeLeon agreed to provide additional graphics of each individual worksite for operations review of the proposed tasks. When the graphics are provided, a review date will be established. Status of the operations review will be provided on March 27 as well. The EVA AIT also requested information on how the contingency bolts are packaged for launch and transport to the worksite.

Action Item Closure: AI-576, 577 remain open

6. Fit Check Matrices Change -12A, 12A.1, 13A Updates DX32/John Haensly

Mr. Haensly reported that he has not received any significant inputs to the FCM updates provided on February 13. Several participants requested additional time to review the changes, so formal update was deferred until March 13.

Significant discussion not included in the presentation material:

There were some discussions about the formatting of changes and format differences between FCMs for different flights. For instance the label row and column has not yet been added to the FCMs provided, as had been previously agreed to in an earlier EVA AIT. There was also discussion about the level of detail required in each line item. Ms. Patrick requested that MOD update the generic matrix and establish consistent formats, but did not issue a formal action to do so. Ms. Patrick also noted that each line item must contain enough information to clearly establish the intended content of the fit check so that schedulers could schedule the fit check to occur when the flight hardware was in the appropriate configuration. Ms. Patrick re-iterated that the controlled portions of the matrix include the task list, and the configuration and tools required columns. Updating the matrix formally through the EVA AIT to reflect fit check results is not required.

7. Fit Check Matrices Status – 7A.1 Baseline, DX32/Rich Gauvreau,

6A, 9A, 11A Updates DX32/Tricia Mack, Chris Looper

The 7A.1 FCM was submitted for baselining and changes to the 6A, 9A and 11A matrix were provided for review. Each of the MOD flight leads reviewed the significant inputs for their respective matrix. Ms. Mack confirmed that the line items deleted from the 6A matrix because they applied to flight 5A.1 have in fact been added to the 5A.1 matrix already. All EVA AIT members were asked to review the inputs and provide comments to the respective flight leads no later than March 12.

Action 583: Review 7A.1, 6A, 9A, 11A, 12A, 12A.1, 13A FCM inputs and provide comments to MOD EVA leads

Actionee: All EVA AIT members

Due Date: March 12, 2001

Method for Closure: Report to EVA AIT

8. EVA standard ICD status follow-up discussion LMES/Mark Messinger,


The EVA AIT reviewed the status of the following ICD PIRNs:

  1. 67B: PIRN was signed — all, including Huntsville had signed

  1. 72A: Revision A was submitted on February 22 and inputs are due March 8. EVA AIT will review status on March 27.

  2. 73: No change since previous reported (B-CP comments received, LMES working on Rev A). LMES estimated submittal of Revision A on March 21. EVA AIT will review status March 27

  3. 74A: Revision A was submitted on February 26 and inputs are due March 8. EVA AIT will review status on March 27.

  4. 75: Signed and closed prior to EVA AIT

  5. 76B: 76B was approved by all parties, including EC5, Ms. Patrick signed.

  6. 79: Non-concurrence from B-CP due to torque tolerance of ±20% rather than ±10% as required for RTAS attachment. No one present knew how the task had been approved for 4A, however the tool can provide better tolerance at certain torques under certain thermal conditions. The EVA AIT suggested that the PIRN be updated to include this information, and note that waivers should be submitted for tighter tolerance requirements, which would be reviewed on a case-by-case basis. The party requiring the tighter torque is responsible for providing the thermal analysis that ensures the tool can be kept within its constraints for tighter tolerance. LMES agreed to submit the revised PIRN, and estimated an ECD of March 9. The EVA AIT will review the status on March 27.

  7. 80: Revision A is in work by LMES, based on comments received, estimated submittal date of March 9. The EVA AIT will review the status on March 27.

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

Ms. Patrick reviewed the preliminary EVA AIT agenda for March 13. Presenters are requested to confirm agenda topics by COB Thursday, March 8.

SpaceRef staff editor.