EVA Tools and Crew Aids Panel Minutes of Meeting October 30, 2000
The EVA Tools and Crew Aids Panel met at JSC on October 30, 2000, in Building 1, Room 966, at 1:00 p.m. Representatives from the following organizations participated:
EVA Project Office
Hardware Development
Engineering Directorate
Crew and Thermal Systems Division
FCE EVA
Safety, Reliability and Quality Assurance Office
Hamilton Standard Management Services
Lockheed Martin
Panel members from the following organizations participated:
XA/Panel Chair, XA/Panel Secretary, CB/Astronaut Office, DX3/EVA, Robotics, and Crew Systems, EC5/Crew and Thermal Systems Division, USA FCE/EVA, and NA/SR&QA.
The following items were presented:
- PRACA Status – NS43/T. Miller
A total of 25 FIARs is open for EVA hardware. Eight FIARs were reported as past due and statused as follows:
BFCE028A005 – PGT Battery – Tongs broken off on J2 power connector.
Off-line discussion to be held. To address at 11/1/00 EHB.
JSCEC0821 – Body Restraint Tether (BRT) – Cuts and pinch points in fabric of debris sleeve.
To add as limited life item in GCAR. To address at 11/1/00 EHB.
BFCE026A022 – Draeger Tube Hydrazine – Discoloration on Draeger Tube.
EC5/H. Rotter working closure. To address at 11/1/00 EHB.
JSCEC0830 – Adjustable Equipment Tether Assy – Loose and broken thread.
Being reworked.
JSCEC0796 – Active WIF Assy – Active WIF control knob appeared to have increased force to operate.
In signature loop.
BFCE026A021 – APFR – Crack through pivot area.
Test piece complete by EM. Lockheed doing test in-house. Present new ECD and rationale at 11/1/00 EHB.
JSCEC0832 – Equipment Hook Assy – Modified latch appears to have weld and grind marks.
New findings indicate hardware not weld marked. EC5 to work final and downgrade these two items. Address 11/1/00 EHB on why we do not need to look at remaining hooks.
JSCEC0833 – ISS Crewlock EVA Bag Assy – Helicoil inserts installed incorrectly.
Pending released DCN from Lockheed.
Two new FIARs were reported as follows:
JSCEC0836F – WIF – During STS-92 EVA1, active WIF of APFR would not hard dock to Zq-WIF-21.
Plan in place. Have thermal and structural data.
JSCEC0837F – MMWS – During STS-92 EVA1, Gimbal Assembly was sticking binding. Gimbal Assembly button (s/N 1004) fell out of assembly.
Working TPS. To disassemble STS-97 Gimbal Assembly buttons.
Per XA/A. Huynh, all SAFER FIAR closures are in work for STS-97.
The EVA hardware oldest FIAR, opened against the Pistol Grip Tool (PGT), is 490 days old.
The total FIARs open by flight is as follows:
STS-97 13
STS-98 20
STS-102 20
- Cert Status – NC52/G. Wright
There are 13 open certification items for STS-97, 11 open certification items for STS-98, and 11 open certification items for STS-102.
- Mission Hardware Status – LM/K. Thomas
- Actions Review – XA/G. LeStourgeon
- Equipment Tethers and Waist Tethers – USA/L. Wible
STS-97: Waiting for 19 pieces of hardware from Bench Review. There are DRs on EHIP batteries. There is a hold on EHIP light processing (fitting ERCAs); will do abbreviated PIA after processing complete
STS-98: Have all items to support pull test. Hardware needs to be shipped for 11/10 on-dock ship date.
STS-100 MPLM ship: All items currently being PIAd except gimbals. Checking on S/Ns to sync up with STS-102 ship.
This item was deferred.
Background: H-0898 – Request for Approval to Change Waist Tether Drawings. Flight and Class III waist tethers and equipment tethers have duplicate serial numbers (S/Ns). This CCBD requested generating a method of standardizing how S/Ns are assigned. The EVA Tools Panel requested USA input. USA response is as follows:
Basics: Flight and Class III Waist Tethers have duplicate serial numbers. Flight and Class III Equipment Tethers 75/30 have duplicate serial numbers.
- Issue:
- Duplicate serial numbers being applied to Flight and Class III hardware.
- FCE/EVAs Shuttle Equipment Tracking System prohibits data input of duplicate serial numbers for a single part number.
- DRs generated.
- Cause:
- Serial numbers for Flight Waist Tethers (P/N SEG33106943) are requested against the Load Alleviating Tether (P/N SEG33108431), a subassembly.
- Serial numbers for Class III Waist Tethers are correctly requested.
- Serial numbers for Flight Equipment Tethers 75/30 (P/N SEG33106164 are requested against the Retractable Equipment Tether (RET) (PN SEG331085154).
- Serial numbers for Class III Equipment Tethers are correctly requested.
- Modifications Required:
- Add fabric label next to current label on Waist Tether to show top assembly P/N configuration. This requires change out of the label if hook sizes are changed.
- Requires change out of label if hook sizes are changed.
- -301 drawing calls out one (1) large and one (1) small crew hook.
- Add metal foil label to RET to show Flight Equipment Tether P/N (including configuration) and serial number – Configuration applied using Flight Sharpie pen – can be erased as configuration changes.
- Impacts:
- Generation of DRs when duplicate serial numbers are received into Bond.
- Hardware identification does not match paperwork.
- Potential for tracking "ghost" serial numbers on EEL and other tracking systems.
- Options for resolution of issue:
- Option 1 for Waist Tethers: Update Waist Tether drawing to reflect addition of new label. Obtain new serial numbers against top assembly for flight hardware. Add subassembly label to Class III Tethers to make "flight-like".
- Option 1 for Equipment Tethers: Update drawing to show addition of metal foil label. Drawing already contains matrix to show configuration options.
- Option 2 for both Waist Tethers and Equipment Tethers: Re-serialize Class III hardware using 9xxx series.
- Implementation need date:
- ASAP to close out DRs and prevent additional DR generation.
- Recommendation:
- Option 1. Hardware will match all paperwork and all tracking systems. Possibility of EDCC issuing duplicate serial numbers is eliminated. Potential generation of DRs eliminated. Potential problems with downgrade of Class I eliminated.
The following action was assigned:
Action 10/30/00-1: Work with EC5/D. Glebe, MV5, and USA to determine what appropriate solution to issue is, e.g., top-level labeling, make Class I hardware same as Class III, or leave as is.
Actionee: XA/D. Roberts
Due Date: 11/13/00
- FIARs on On-Orbit Hardware – XA/K. OBrien
There are 11 tools currently on-orbit with unaddressed FIARs. FIARs were opened against these tools when they were already on orbit. A plan for addressing the tools still on orbit needs to be developed.
Options for resolving the issue were outlined as follows:
- Some tools already have a plan either to bring items home or to fix on orbit.
- Some tools can probably be left on orbit as is and fixed when returned from Station after 15 years (DRs are open to track these discrepancies).
- Some tools need to be brought home and reworked at the first opportunity.
- Some tools need a developed action plan.
Recommendations for each piece of on-orbit hardware were also presented. (See tables on following pages.)
This presentation will be brought to the 11/1/00 EHB.
Tools that Already Have a Plan of Action
Part Description | Open FIARs | FIAR Description | Comments |
Portable Foot Restraint (PFR) P/N SED33105308-301 | JSCEC0771 | Gimbal joint problems | Returned on STS-92 (3A) |
JSCEC0772 | Incorrect threaded fasteners | ||
MUT Tool Carrier P/N SEG33109980-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | Plan for on-orbit hook replacement on STS-97 (4A) |
Recommended Actions: None
Recommendation: Leave Tools On-Orbit and Use As-Is
Part Description | Open FIARs | FIAR Description | Comments |
EVA Aux Bag P/N SEG33111904-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | -Strapped to the Node Bag by 4 hooks. – Considered highly unlikely that all 4 hooks would be opened inadvertently. |
Node Bag P/N SDG33110764-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | – This hook only holds the lid open on Node Bag. – Does not present a risk of losing equipment. |
OHTS Bag P/N SEG33110765-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | – Strapped to the Node Bag by 3 hooks. – Considered highly unlikely that all 3 hooks would be opened inadvertently. |
ORU Transfer Device P/N SEG33106254-303 | JSCEC0796 | High force to actuate Active WIF Control Knob | – Discrepancy happened on the Life Cycle Testing Unit (experienced much higher cycles than flight unit) – Force to actuate knob is still within specifications. |
Recommended Actions:
EC5 – Use rationale in comments for final closure of FIARs.
SR&QA – Open DRs on any of the above on-orbit hardware that does not already have one.
Recommendation: Bring Home for Rework at First Opportunity
Part Description | Open FIARs | FIAR Description | Comments |
High Strength Bridge Clamp P/N SED33107177-301 | JSCEC0827 | Contingency Release Pin drops out of Assy | – Return for rework since HSBC is no longer needed on-orbit for 96 Bolt Contingency Task. |
Push Button Articulating Socket P/N SED33105422-313 | JSCEC0786 | Thermal testing issues with Lock-Lock and Paddle | – Return for rework since PBAS is no longer needed on-orbit for 96 Bolt Contingency Task. |
Recommended Actions:
XA, I&O/MOD: Incorporate into first available EVA to bring these items home.
Recommendation: Develop an Action Plan
Part Description | Open FIARs | FIAR Description | Comments |
Adjustable Fuse Tether P/N SED39127200-701 | JSCEC0681 | Binding of Shuttle Hooks during fitchecks | – DRs are open to track once the tethers are returned. |
JSCEC0685 | Binding of Shuttle Hooks during thermal testing | ||
JSCEC0698 | Sharp edge on CAM Buckle | ||
ORU Tether P/N SEG33108800-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | – One attached to OTD and 2 to PFRWS. |
OTD (Tether Reel) P/N SEG33109707-301 | JSCEC0773 | Inadvertent opening of Equipment Hooks | – Discrepant hook is located on the tether Reel attached to the OTD. – Used for P6 maintenance tasks. |
Recommended Actions:
EC5: Determine if equipment hooks on ORU Tether and OTD Tether Reel could be changed out on-orbit.
- Aux Bag 02 Issue – EC5/G. Nickel
The objective of this presentation is to confirm there is no issue to fly the Aux Bag 02 (as built) on STS-97 for installation on the P6 truss, to determine if further evaluation is needed for hardware already on orbit, and to determine if a generic change is required for use of small stainless steel hardware items.
The maximum on-orbit temperature of stainless D-rings used in the adjustable tether straps of EVA bags is predicted by thermal analysis to reach +370° F and cause damage to the EMU or gloves. Affected flight articles are the Aux Bag 02, SEG33113891-301 and previous bags (Node bag, OHTS Bag, Aux Bag 01). Future bags include the TCS Vent Tool Stowage Bag and other items equipped with shiny French hooks.
Unmodified (shiny) D-rings were in use before the hazard was identified and surface blasting was implemented to improve the absorptivity/emissivity Aux Bag 02 delivery schedule dictated fastest possible fabrication, and no dull rings were available.
It is impractical to replace rings on Aux Bag 02 for flight 4a and impossible to replace rings on bags already flying. A protective cover could be installed to shield D-rings from direct sun.
There is potential permanent damage to the EMU and/or gloves. There is significant cost for developing and fabricating protective covers and significant EA time required to install covers. Crew training could be implemented to avoid exposed shiny rings.
There is no immediate concern. The Lockheed thermal group has determined that there is little or no risk of damage during deployment and installation of Aux Bag 02 on flight 4A due to the limited time of exposure of hook to the Sun.
EC5/G. Nickel recommended that no change be made to Aux Bag 02. Preliminary discussions with MOD indicate that Crew and MOD generally agree that previous thermal analyses are too conservative and have often been disproved on missions already completed. Such warnings, often issued very late in the schedule, cause undue burden on those trying to plan EVAs and those certifying tools and equipment. Crew and MOD appear to agree that the D-ring issue, in general, is not a problem that needs attention at this time. Lockheed may disagree.
The consequence of not implementing the no change recommendation is that a last minute rush to implement a fix wold be disruptive to other tasks with higher priority. Not implementing the no change recommendation will require a significant amount of work to develop a believable mode, develop appropriate levels of protection, and develop additional on-orbit tasks to install them.
This presentation, as well as a presentation on the Node Bag access will be brought to the 11/1/00 EHB.
- D-Rings on EVA Softgoods Bags – LOC/B. Conger
A counterpoint to the Aux Bag 02 Issue was presented.
Per LOC/B. Conger, stainless steel D-rings currently used on some EVA softgoods do present a hazard for the EMU. CTSD testing shows that EMU insulation is degraded when contacting objects greater than 320° F for more than 3 seconds. Thermal analyses predict that D-rings used on EVA softgoods bags will exceed 320° F in 4.5 hours in a sun oriented attitude such as XPOP.
Exterior-mounted and isolated bare metal is the main issue with D-ring design. Bare metals like stainless steel cannot radiate trapped solar heat efficiently. Exterior D-rigs on the softgoods bags do not make contact with other materials which could conduct the heat away. EVA softgoods bags left mounted to ISS structure between STS missions have plenty of time to overheat. Anodized aluminum and other coated metals are efficient at radiating excess heat. Stainless steel French hooks also fall into the category of poor thermal designs.
A thermal analysis was conducted using a D-ring hovering just above a flat beta cloth surface. The analysis is generic and could represent any time that the Sun is shining directly on the D-ring. Results of the analysis show that Sun-lit D-rings can exceed 320° F in <4.5 hours and reach 350° F in 8 hours at the 26° beta angle (orientation for 3A and 4A). Transient contact analysis shows that it takes more than 60 seconds to cool D-rings to less than 320° F while contacting the EMU TMG.
CTSD Materials Laboratory testing shows degradation of the TMG when contacted with a 320° F object. The EMU TMG degraded after 3 seconds of contact with a 320° F object at 1 psi force. Adhesive used to hold scrim to each MLI layer flows and permanently fuses MLI layers at this temperature and eliminates the vacuum radiation barrier. The external ortho fabric layer will oily discolor at this temperature if it was contaminated (no visible indication of problem). The EMU Pressure Bladder softens at 160° F and could be compromised with continued contact with a 320° F object. The EMU glove palm does not contain the TMG and would not necessarily be an issue with hot D-rings.
For STS-97, preliminary review indicates that the crew will not be working in the vicinity of hot D-rings for EVAs 1 and 2. The potential EA 3 would move the Node Bag aside to access cabling locations. If EVA crewmembers only contact D-rings and French hooks with the glove palms, the TMG damage could be avoided.
There is a need to evaluate potential for contact with D-rings and French hooks on future missions, including Station-based EVAs. The Node Bag has 8 external D-rings and 6 French Hooks which heed to be addressed. Auxiliary Bags -01 and -02 have D-rings, which also deserve review.
This presentation will be brought to the 11/1/00 EHB.
No further items were submitted and the Tools Panel adjourned.
Submitted by: Approved by:
(Original signed by) (Original signed by)
________________________________ ________________________________
Harriett A. Attaway D. G. LeStourgeon
EVA Tools & Crew Aids Panel Secretary Acting EVA Tools & Crew Aids Panel Chairman
Note: CARD changes are normally routed for concurrence after the Panel adjourns. Initiators are requested to be present or have representation for discussion of the change.