Status Report

Minutes for February 13, 2001 EVA AIT

By SpaceRef Editor
February 13, 2001
Filed under ,

To: Distribution

From: XA/Nancy J. Patrick

Subject: Minutes for February 13, 2001EVA AIT

The EVA AIT met at the Johnson Space Center on February 13, 2001. Boeing/Lou Ramon 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, OM/ISS Mission Integration, OC/ISS Operations Office and Boeing-Houston (EVA and Safety) were present. 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/Lou Ramon

XA/Nancy Patrick

The Following Action Items were reviewed:

AI-510: This action was CLOSED. Mr. Zingrebe confirmed with Boeing-Houston and Boeing-Canoga Park L&M representatives that they do propose updates to OP-04 procedures based on the results of PIDS exception development, analysis, test and fit check results. NASA formally approves the changes, however the hardware provider initiates them.

AI-556: This action remains open and will be discussed again on February 27. LMES/Grant Bue had not yet delivered the thermal analysis for the flights involved, so Mr. Adams could not perform the operations assessment.

AI-570: This action remains open and will be discussed again on February 27. The testing had been delayed until no earlier than February 15.

AI-572: This action remains open and will be discussed again on February 27. The testing had been delayed until no earlier than February 15.

AI-573: This action remains open and will be discussed again on February 27. The testing had been delayed until no earlier than February 15.

AI-575: This action was CLOSED. Mr. Adams reported that MOD has no issues with the SSRMS maintenance before MBS delivery procedures provided by CSA.


2. External Television Camera Group (ETVCG) B-Hou/Lou Ramon

Robot Compatibility

Mr. Ramon reported that the ETVCG does not comply with the frequency requirements for robot compatibility and that Boeing has requested a program decision on whether to redesign to meet the requirements or delete the ETVCG from the robotically compatible ORU list. Mr. Ramon noted that the ETVCG is not robotically compatible for relocation, because relocation of the ETVCG requires relocation of the camera stanchion and they are not compatible. Mr. Ramon also noted the Boeing-Huntington Beach has already accounted for EVA time for ETVCG maintenance in their logistics plans.

Significant discussion not included in the presentation material:

There were a lot of questions about the assembly and maintenance operations associated with the ETVCG. According to OC/Bill Robbins, the maintenance community has some significant issues to deal with for this ORU. The ORU is too large to launch and transport as a single integrated unit, however assembly of the unit involves precise assembly involving special tools and training. The manufacturer recommends against on-orbit assembly.

The EVA AIT concluded that additional information on the planned assembly tasks is needed to evaluate the task, and that the maintenance group needs to complete their maintenance concepts before the EVA AIT should address EVA only maintenance. PG1/Larry Price agreed to provide the Boeing plans and procedures for the installation of the ETVCG and camera stanchions on the assembly flights where they are delivered to begin addressing the issue.

Action 580: Provide OP-01 assembly procedures and launch configuration data for ETVCG and camera stanchion hardware, planned for launch on inboard truss segment flights. Indicate whether the ETVCG is launched as an integrated ORU or requires on-orbit assembly.

Actionee: PG1/Larry Price

Due Date: March 13, 2001

Method for Closure: Present to EVA AIT

3. SSCN 2741 – PVR Interference Issue Resolution Plan OB/Phil Dempsey, PG2/Scott Boller, Don Hood, OC/Joe LaRochelle

The EVA AIT facilitated a chart review for the VSIP splinter review of open issues concerning SSCN 2741. The presentations reviewed addressed a P6 off-set bracket for the spare PVR, a P5 plate to stow the spare PVR, and providing a deployable carrier on 12A.1 that can house the PVR on the P3 ULCAS.

The SSCN provides for several things to support launch to activation issues with S4, P4 and S6, including adding a full complement of batteries for all PV modules, and a PV Radiator to S6. The only remaining issue with the SSCN is location of the spare PVR on P6 (currently an EEATCS radiator) that had been designated as the S6 radiator. The current location interferes with the installation of the MT/CETA rails and from previous discussions at the EVA AIT and VSIP, deletion of the rails results in a significant EVA impact for PVM maintenance, and some ORUs are impossible to maintain without the rails.

During the summer of 2000 at the EVA AIT, and in October at the VSIP, the favored option was to install an off-set bracket at the P6 spare PVR location that moved the radiator out of the way of the rails. During technical definition, Canoga Park determined that the required design to meet on-orbit EVA loads would be difficult to implement and install on-orbit. The off-set bracket would transfer loads back to Acme screws in a direction that the screws are not designed to take. To reduce the load, an additional brace would be required between the legs of the bracket. Canoga Park identified several EVA concerns with this option and proposed a stowage plate to be installed on the P5 trunnions, using the UTAS. Canoga Park provided a description of the pros and cons for each of these items as well as a summary of the sequence of events since October that led them to recommend the new option. Unfortunately, because the issues with the off-set bracket surfaced late, there was neither time nor money left to fully define the P5 plate option, and the ROM had to be conservative. The resulting ROM was much higher than expected and the VSIP requested further review.

During meetings to address the VSIP concerns, another option was proposed by OC/Joe LaRochelle. He proposed providing a deployable carrier that would be stowed on-orbit on one of the P3 ULCAS sites to house critical spares and failed ORUs. This has been defined as a long-term requirement to support ISS maintenance, but no firm need date has been established. Mr. LaRochelle indicated that a good time to implement this carrier would be the 12A.1 timeframe, which allows for the PVR to be relocated well before the MT/CETA rails are required. This would involve at worst an acceleration of the cost associated with the carrier.

The EVA AIT reviewed the pros and cons between the PVR stowage options and determined that there is no clear preference for EVA between the P5 and the P6 stowage locations. Both options have some advantages and disadvantages. The P5 option does not require temporary relocation of the PVR while the plate is being installed, however it requires longer electrical cables that must be installed EVA. It also provides better reach for the SSRMS. The P6 option has the advantage of shorter jumper cables and known worksites since the radiator must be removed from P6. Both options were considered acceptable for EVA. The EVA AIT concluded, for several reasons that the preferred EVA option was the deployable carrier. The carrier allows the PVR to be transported to whichever PVM needed it without EVA, since the carrier can be removed and temporarily stowed on the MBS. This requires EVA only to install it once it is at the worksite. Providing the carrier also improves the maintenance situation for other ISS ORUs. The EVA AIT noted that it is possible to defer decision to fund the carrier until the lack of rails becomes a significant issue. This would add EVA overhead for P6 maintenance and would preclude maintaining some ORUs, but once the overhead becomes too cumbersome or the subject ORUs are required, the carrier can alleviate this.

Decision: The EVA AIT determined that the preferred on-orbit stowage method for the spare P6 PVR is to provide a deployable carrier that can house the radiator and other ORUs on the P3 ULCAS when the P6 outboard rails are required.

Note: The VSIP splinter discussion resulted in a decision to discontinue further Vehicle office development of a unique PVR stowage device and to defer to the Operations office to provide a deployable carrier when required.

4. MSS Extension Cord Overview — SSCN 4886 B-Hou/Noe De La Peña

Mr. De La Peña requested EVA AIT review of the MSS EVA extension cord proposed in SSCN 4634. The extension cord is required to keep the MSS equipment alive should the MT stall between utility ports. The cable would connect a truss passive UMA to the MBS at the MBS-to-MT power connection. The cable is only connected if the MT fails, and is sized to reach the MT from the furthest possible distance from a utility port. An earlier change adds a battery to the MBS to provide power until the cable can be connected.

The proposal allows for storing the cable on the MBS, however the location is TBD. Mr. De La Peña proposed using an "EVA bag" for storing the cable. The EVA AIT informed him that there are no generic EVA bags and no extras of the existing EVA bags, and that if one was required he should add the cost to the SSCN.

Significant discussion not included in the presentation material:

EVA AIT members concurred that there should be no issue with installing the cable. The interfaces are accessible provided the MT is not on top of the truss/passive UMA connection. The MBS side of the connection should be fine since it attaches at the same location where the MT to MBS power is attached during normal assembly. The EVA AIT noted that the active UMA is in the immediate vicinity of the MT to MBS power connection. This is significant since the UMA active half does not meet EVA inadvertent contact loads (reference SSCN 4886, approved by EVA AIT on January 30, 2001). The EVA AIT concurred that there is nothing that could really be done to alleviate that concern, and that the EVA crew will just have to be trained to be careful around the UMA if the cable has to be connected and the MT serviced in between utility ports.

The EVAA IT also noted that other requirements for a storage capability on the MBS are surfacing, and should be considered when developing stowage for this cable. CA/Fernando Ramos noted that if the SSRMS has to be powered down for servicing, thermal blankets have to be installed to keep components from freezing. The program has to provide on-orbit stowage for these blankets also. Mr. De La Peña and OM/Henry Orosco agreed to coordinate the stowage requirements to the extent possible.

Finally, Mr. De La Peña noted that under some circumstances, the MBS battery only lasts for 48 hours before the extension cable has to be connected. The EVA AIT was concerned that the EVA response time could be so short, and noted that this is probably not acceptable. No one present knew the exact EVA response time for ISS operations, however all concurred that 48 hours is too short for standard ISS operations. A shorter response time can be provided, but only for specific, critical time periods. The shorter rapid response time requires preparing the airlock, suits and crew prior to the failure occurring, which diverts time from other ISS operations. Allowing for this rapid response time anytime the MT was translating would negatively impact ISS operations.

Decision: The EVA AIT concurred with adding the MSS extension cable and does not see any problem with installing it if needed. The EVA AIT noted that cable stowage needs to be addressed and that the response time for installing the cable should provide for standard ISS failure response time.

5. P6 Relocation Resolution Plan — MBS to Z1 cable OC/Phil Jenkins

Installation — SSCN 3878 PG2/Scott Boller

Mr. Jenkins described the proposal in SSCN 3878 that adds two cables designed to provide power, command and data to P6 ORUs while P6 is on the MBS. One cable provides power from the MBS through a PDGF that would be installed on P6 specifically for relocation (P6 was scarred for the PDGF prior to launch). The second cable provides command and data handling of the P6 ORUs through a cable from the PDGF back to the RPCMs on Z1. The command and data cable has to connect back to Z1 because ISS software only recognizes the data path to P6 through the Z1 RPCMs. Routing command and data through the MBS would require a software change, which was deemed too expensive.

The proposed operational scenario has the EVA crew disconnect P6 from Z1, then the SSRMS translates P6 to the MBS and the EVA crew connects the power cable from the PDGF to the P6 junction box. The MBS then translates to P3 and the EVA crew connects the command and data cable between the PDGF and Z1. According to DO/Assembly Operations, this could all be accomplished during the same EVA. P6 is then placed in a thermally stable SSRMS position ("parked") until it can be attached to P5.

The current baseline (without the cable connections) includes back-to-back, orbiter present EVAs to first disconnect P6 from Z1, then attach P6 to P5 on consecutive flight days, resulting in a nominal P6 unpowered time of 27 hours. Analysis has shown that P6 will survive 51 hours unpowered, and the nominal scenario can accommodate 24 hours contingency in case a day must be added between EVAs due to a contingency. However the Launch Package team was concerned about meeting shuttle contingencies that require MDF and/or rapid safing that would require the orbiter to leave in between when P6 was disconnected from P6 and then connected at P5.

The EVA AIT questioned whether the cables could be installed on the same EVA that disconnects P6 from Z1. The presumption on this requirement was that the ISS crew could not respond fast enough to connect the cables in time if the orbiter crew had to leave. Crew training and ISS EVA response time were cited as concerns. The EVA AIT noted that the standard response time and level of training would support this assumption, but for a time critical, assembly critical activity like P6 relocation, the crew could be trained and ready to respond to the failure. The EVA AIT finally concluded that there is no EVA issue with providing the cables, and that we have time to evaluate the options for how and when they are installed during flight development over the next several years. The EVA AIT noted that while there is no EVA objection to building the cables, EVA does not have a position on whether the cables are required. The EVA AIT believed that there are other equally vulnerable and equally important cargo elements and there are no provisions for contingency power for those elements during their assembly. Finally, the EVA AIT noted that provisions for launch, on-orbit transport (e.g. cable caddie) and on-orbit stowage should be included in the SSCN for the launch package team to address.

Decision: The EVA AIT concluded that there are no significant issues with providing EVA installed power, data and command cables for P6 relocation. The EVA AIT deferred judgment on whether the cables are required to the launch package and vehicle teams.

Note: The VSIP recommended canceling SSCN 3878 on February 15. Mr. Jenkins and Mr. Torcivia plan to appeal to the MIOCB and/or VCB.

6. Fit Check Matrices Status – 12A, 12A.1, 13A Updates DX32/John Haensly

Changes were distributed to the subject fit check matrices. Ms. Patrick requested EVA AIT members review the changes and provide comments to Mr. Haensly by February 26. The EVA AIT will review controversial items and disposition the changes on February 27.

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

Ms. Patrick reviewed the preliminary EVA AIT agenda for February 27. Presenters are requested to confirm agenda topics by COB Thursday, February 22. Ms. Patrick noted that the preliminary agenda is very full and that it is important to confirm support as soon as possible.

Deferred by EVA AIT Chair due to time constraints

Status of FRAM/EVA tools integration tiger team B-Hou/Gary Graybeal,

XA/Dale Roberts

Report results of December 14 discussion and status of review of the ORU list to define operational requirements for interfaces to CETA, OTD and TERA.

Decision Required: None at this time — information only

Required Attendees: XA, Boeing-Houston, DX32, CB, NC, EC5, LMES, KSC/SSHIO, PGs, SLP

The following item was deferred until February 27 because the testing has been delayed:

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

Report results of PM-A and NTA installation on P1, including recommendation on whether ORU blanket will interfere with the ORU guide rails. Report status of discussions within PG1 on whether the issue will be resolved with a design change — including IRB discussion plan.

Decision Required:

Required Attendees: XA, Boeing-Houston, DX32, CB, CA, NC, KSC/SSHIO, PGs, SLP

Action Item Closure: AI-570, 572, 573

The following item was deferred until February 27:

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

6A DX32/Tricia Mack

Provide 7A.1 fit check matrix (task list distributed 1/30, provide full matrix today) and highlight any controversial or significant line items for AIT reviewers. Provide changes to 6A, 12A, 12A.1 and 13A FCM updates, highlighting the changes proposed to the baselined matrices.

Decision Required: None at this time — information only

Required Attendees: XA, Boeing-Houston, DX32, CB, NC, EC5, KSC/SSHIO, PGs, SLP

SpaceRef staff editor.