SSP-50699-04_Rev_A.docx

Certification Baseline Document Volume 4: International Space Station Lifetime Extension

International Space Station Program

Revision A

February 2013

Type 4

EXPORT CONTROLLED - The technology or software is subject to the Export Administration Regulations (15 C.F.R. Parts 730-774). Export, re-export or retransfer contrary to U.S. law is prohibited. EAR99

National Aeronautics and Space Administration International Space Station Program Johnson Space Center Houston, Texas Contract No.: NAS15-10000

SSP 50699-04

Revision A

REVISION AND HISTORY PAGE

A Initial Release (Reference per SSCD 013139, EFF. 03-22-12)

Revision A (Reference per SSCD 13550 EFF. 03-12-13) 04-06-12

04-29-16

ERU: /s/ Colleen Lippert 04-29-16 certification baseline document volume 4 inteRNATIONAL SPACE STATION PROGRAM lifetime extension

PREFACE

The Certification Baseline Volume 4 International Space Station (ISS) Lifetime Extension document provides a record of the analyses and assessments performed to extend ISS operational/service lifetime through 2028. This document is developed in accordance with Space Station Change Directive (SSCD) 12745 and consolidates the analytical data, results, and disposition of identified issues in a single source. The document will also serve as supporting evidence for Certification of Flight Readiness (CoFR) for flights occurring after the expiration of operational/service life requirements for applicable hardware in a phased release approach.

This document is under the control of the Space Station Control Board (SSCB).

certification baseline document volume 4 lifetime extension

CONCURRENCE

February 2013 certification baseline document volume 4 lifetime extension INTERNATIONAL Partner CONCURRENCE

FEBRUARY 2013

CSA:

Pierre Jean

CSA

PRINT NAME

ORG

/s/ Pierre Jean

5/30/2013

SIGNATURE

DATE

ESA

PRINT NAME

ORG

/s/ Patrick Sever

4/18/13

SIGNATURE

DATE

JAXA

PRINT NAME

org

/s/ Masazumi Miyake

5/13/2013

SIGNATURE

DATE

ASI

PRINT NAME

org

/s/ Silvana Rabbia

3/19/2013

SIGNATURE

DATE

certification baseline document volume 4

INTERNATIONAL SPACE STATION

LIFETIME EXTENSION

LIST OF CHANGES

February 2013

All changes to paragraphs, tables, and figures in this document are shown below:

Board Name

Entry Date

Change

Paragraph(s)

SSPCB

March 2012

Baseline

All

SS

SSPCB

February 2013

Rev A

Added Table 4-1 Rewrites and updates throughout the document adding component, hardware, and systems lifetime assessment results

TABLE OF CONTENTS

FIGURES PAGE

3.1-1 OVERALL ISS LIFETIME EXTENSION APPROACH………………………….……………………..……………3-3

3.1.2-1 SECONDARY STRUCTURAL ANALYSIS APPROACH………………………….………………....…………3-7

3.1.3.1-1 ORU HARDWARE REVIEW PROCESS…………………………………………….………………….……….3-9

3.1.3.3-1 SUBSYSTEM LEVEL ASSESSMENT PLAN……………………………………………..………………..….3-12

3.1.3.3-2 STRUCTURAL ANALYSIS ASSESSMENT PLAN FOR FRACTURE CRITICAL ELEMENTS….3-13

3.1.3.5-1 PAYLOAD FACILITIES ASSESSMENT PROCESS…………………………………………………..……..3-14

3.1.4-1 2020/2028 LOGISTICS SUPPORT REQUIREMENTS DETERMINATION PROCESS……..…..3-16

3.1.5-1 SAFETY AND MISSION ASSURANCE ASSESSMENTS………………………………………..…......… 3-18

3.1.5-2 HARDWARE HAZARD MANAGEMENT TOOL………………………………………………….….….…..3-19

TABLES PAGE

1.4-1 CATEGORIES PER SSP 30234 REV. F DCN002……………………………………………………………...….1-3

3-1 ISS ELEMENT ORIGINAL STRUCTURAL LIFETIMES……………………………………………….………….….3-1

3.1.3.3-1 NO ANALYSIS REQUIRED FRACTURE CRITICAL COMPONENTS……………………..…….…..3-10

3.1.3.3-2 ANALYSIS REQUIRED FRACTURE CRITICAL COMPONENTS………….……………………….….3-11

3.1.3.5-1 PAYLOAD FACILITIES FOR ASSESSMENT……………………………………………………….…...…..3-15

4-1 ELEMENT HARDWARE SUMMARY………………………………………………………………………………….…4-1

4.1.2.2-1 PAYLOAD FACILITY SAFETY OPERATIONAL AND/OR DESIGN LIFE EXPIRATION DATE………………………………………………………………………………………………………………………………….…4-21 i

INTRODUCTIOn Many factors, including development delays and the Columbia accident, resulted in a longer than anticipated assembly sequence of the International Space Station (ISS). The National Aeronautics and Space Administration (NASA) Authorization Act of 2010 extended support of the ISS to at least 2020 for international and commercial collaboration and growth, research, and technology development to maximize the scientific return on the significant investment in the ISS. This certification baseline document shall satisfy the following objectives: 1) provide the ground rules and assumptions for ISS lifetime extension certification; 2) provide general approaches documenting rationale for reviews, analyses, and other lifetime extension work; 3) provide the results and conclusions of lifetime extension analyses, testing, and reviews; and 4) serve as the source data supporting Certification of Flight Readiness (CoFR) for flights that occur after the expiration date of the formal hardware certification. The technical assessments described herein strive to meet this goal.

This is Volume 4 of a set of books. Volume 1 documents the formal certification of United States On-Orbit Segment (USOS) hardware based on acceptance test data that includes the as-designed and tested verification records. Volume 2 documents any expansions to the hardware operational requirements beyond the formal certification for the Orbital Replacement Units (ORUs) and the system-level hardware based on analytical results driven by Program operational needs. Volume 3 documents additional operational flight attitudes that have been approved for use by all ISS Program participants which are outside the original design specification flight attitude envelope. The Certification Baseline Volume 4 describes the ground rules and assumptions as well as the basic process NASA is utilizing for the ISS lifetime extension technical assessments.

Certification Baseline Volumes 2 through 4 represent the ISS Program’s rationale and agreement to operate the ISS in a manner beyond formal certification limits as bounded by the requirements in the design specifications and associated verification of those requirements. The Program has chosen to analytically determine ISS capability to be operated beyond its formal certification in a disciplined and documented approach to ensure that the ISS remains a safe and viable laboratory as its utilization evolves over time. This approach avoids the cost prohibitive alternative to perform a formal re-certification and verification of all the design requirements impacted by a change in operational philosophy.

PURPOSE

SSCN 12745 authorized the development of SSP 50699-04 Volume 4, Certification Baseline Document Volume 4: International Space Station Lifetime Extension. The ISS Program seeks to extend the operational/service lifetime of the ISS through 2028. This document will define and document the definition and description for the ISS with respect to lifetime extension beyond the development requirements as previously allocated from SSP 41000, System Specification for the International Space Station. This definition and the resultant analytical data are required to properly manage, control, and operate the ISS systems and equipment beyond the original design requirements. This document will consolidate the analytical data, results, issues, and disposition of identified issues in a single source and will serve as supporting evidence for CoFR for flights occurring after the expiration of operational/service life requirements for applicable hardware in a phased release approach. The document will also provide the ISS Program with an auditable and traceable product to capture the results of the ISS lifetime extension efforts.

SCOPE

This document addresses hardware under the responsibility and operations of NASA. Other hardware managed and operated by other International Partners and Participants may be referenced for completeness.

PRECEDENCE

In the event of a conflict between the text of this document and the references cited herein, the reference takes precedence. Nothing in this document, however, will supersede applicable laws and regulations unless a specific exemption has been obtained.

Definitions Assessment – Method for performing verification/certification analogous to Analysis, Inspection, Demonstration, Test (AIDT) verification methods.

Catastrophic Hazard – Any condition which may cause a disabling or fatal personnel injury, or cause loss of the following: the Orbiter, ISS or major ground facility. Loss of ISS: Loss of the ISS is to be limited to those conditions resulting from failures or damages to elements in the critical path of the ISS that render the ISS unusable for operations, even with contingency repair or replacement of hardware, or which render the ISS in a condition which prevents further rendezvous and docking operations with ISS launch elements. (SSP 30309 Rev F, Safety Analysis and Risk Assessment Requirements Document) Certification – The formal written act whereby a responsible official attests to the satisfactory accomplishment of specified activities and authorizes the specified hardware/software, procedures, facilities and/or personnel for program usage. (D684-10020-01 Rev B, Program Master Integration and Verification Plan [PMI&VP]) Critical Hazard – Any condition which may cause a non-disabling personal injury, severe occupational illness; loss of an ISS element, on-orbit life sustaining or emergency system; or involves damage to the orbiter or a major ground facility. For safety failure tolerance considerations, critical hazards include loss of ISS elements that are not in the critical path which can be restored through contingency repair. (SSP 30309 Rev F) Primary Structure – The part of a flight vehicle or element which sustains the significant applied loads and provides main load paths for distributing reactions to applied loads. Also the main structure which is required to sustain the significant applied loads, including pressure and thermal loads, and which, if it fails, creates a catastrophic hazard. If a component is small enough and in an environment where no serious threat is imposed if it breaks, then it is not primary structure.

Secondary Structure – The internal or external structure which is used to attach small components, provide storage, and to make either an internal volume or external surface usable. Secondary structure attaches to and is supported by primary structure.

Structure – All components and assemblies designed to sustain loads or pressures, provide stiffness and stability, or provide support or containment.

Verification – A set of activities performed to ensure that facilities, hardware and software products, and operational procedures comply with the specification requirements imposed on them. (D684-10020-01 Rev B) Validation – A set of activities performed to ensure that each product reflects an accurate interpretation and execution of requirements and meets a level of functionality and performance that is acceptable to users. (D684-10020-01 Rev B) Table 1.4-1 lists for criticality categories per SSP 30234 Rev G.

TABLE 1.4-1 CATEGORIES PER SSP 30234 REV. G

delegation of authority None

2-2

DOCUMENTS

applicable documents The following documents include specifications, models, standards, guidelines, handbooks, and other special publications. The documents listed in this paragraph are applicable to the extent specified herein. Inclusion of applicable documents herein does not in any way supersede the order of precedence identified in Paragraph 1.3 of this document.

reference documents The following documents contain supplemental information to guide the user in the application of this document. These reference documents may or may not be specifically cited within the text of this document.

D684-10020-01 Program Master Integration and Verification Plan (PMI&VP)

MIL-STD-1522(a) Standard General Requirements for Safe Design and Operation of Pressurized Missile and Space Systems

SSP 30309 Safety Analysis and Risk Assessment Requirements Document

SSP 41160 European Space Agency Segment Specification for Columbus

SSP 41162 Segment Specification for the United States On-Orbit

SSP 41163 Russian Segment Specification

SSP 41164 Italian Multi-Purpose Logistics Module (MPLM)

SSP 41165 Segment Specification for the Japanese Experiment Module

SSP 41167 Mobile servicing System Segment Specification for the International Space Station

SSP 50021 Safety Requirements Document

SSP 50869 Prime Item Development Specification for the Permanent Multipurpose Module (PMM) BACKGROUND and Assumptions The ISS was originally planned to have an operational life of 10 years per SSP 50011-01, Concept of Operation and Utilization (COU). Original structural requirements as defined in SSP 41000 and allocated to ISS elements were 15 years. Fifteen years was chosen as the COU called for 5 years to assemble the ISS to its assembly complete configuration and 10 years of operations thereafter. Due to delays in on-orbit deliveries including the Columbia accident, the assembly sequence took 12 years to complete versus the original plan of 5 years. In order to gain as much benefit as possible from the orbiting laboratory now that it is complete, the ISS Program seeks to extend the operational lifetime through the year 2028. Table 3-1 lists the original lifetime limitations of ISS hardware including International Partners’ (IPs) original lifetime limitations.

NASA generated an operational baseline assumptions plan which includes assumptions on vehicle traffic and robotics operations as well as crew size for the structural and robotics team to assess the capability of the ISS primary structures through 2028. This plan represents the assumptions baseline for all teams and IPs to utilize when performing lifetime extension assessments. The lifetime extension assumptions were presented to the Program Integration Control Board (PICB) on December 9, 2009. The assumptions were updated on March 8, 2010 with the agreed to robotics assumptions. Concurrence was obtained on a set of assumptions to be used in the ISS lifetime extension analysis.

Data that supports lifetime extension is located in the Electronic Data Management System (EDMS) in the ISS Vehicle Office Cabinet in the folder ISS Lifetime Extension: https://iss-www.jsc.nasa.gov/nwo/apps/edms/web/.

TABLE 3-1 – ISS ELEMENT ORIGINAL STRUCTURAL LIFETIMES

US Lifetime Extension assessment Approaches Lifetime extension of the ISS will be achieved through assessment of:

· Critical operating hardware, failure of which would be catastrophic, such as primary structure, pressure vessels,

· Critical operating hardware that is not replaceable and which has no identified operational workaround, such as propulsion system, seals, etc.

· Orbital Replacement Units or components for which a service time or cycle issue would drive limited life or operational reductions, such as bellows or Quick Disconnects (QDs)

· Review of hazard reports/Critical Items Lists/other program documentation to identify technical issues specific to continued operation.

Conclusions will be presented to the ISS Program Manager for direction and decisions on mitigations or forward work to enable the ISS to operate through 2028. Figure 3.1-1, ISS USOS Lifetime Approach, depicts the overall high level process.

Figure 3.1-1- ISS USOS LIFETIME EXTENSION APPROACH

Primary Structure Approach The United States (US) primary structural hardware was designed for a 15 year on-orbit life. The Structural Health Assessment Program (SHAP) provides an assessment of ISS structural life usage as compared to design. The lifetime extension approach for US structural hardware is to initially pursue lifetime extension via assessment/analysis alone.

A three-phase assessment approach is being pursued. Phase I will assess Boeing-sustained hardware installed through Flight 7A. Phase II will assess Boeing-sustained hardware installed from Flight 7A through 11A. Phase III will assess Boeing-sustained hardware installed after Flight 11A except for the External Logistics Carriers (ELCs). ELCs will not be reviewed as part of the secondary structure effort. A Change Request (CR) will be required for the Phase IV lifetime extension for any reviews of the ELC. This approach was agreed to with the COTR as part of CR 11967 (ELCs sustaining). Forward action plans will be developed for any area requiring additional work as a result of the conducted assessments.

Functional Cargo Block The Functional Cargo Block (FGB), although designed and built by Russia, is the responsibility of NASA. The FGB was procured by NASA as part of a subcontract to the Khrunichev Space Center (KhSC) through Boeing, the ISS Prime Contractor. It was not considered part of the balance of contributions per the original Memorandums of Agreement (MOAs) with the IPs.

The FGB primary structure and docking system are being analyzed utilizing data obtained through testing the FGB structural test article to the equivalent life of 2028. Additionally critical systems and non-replaceable hardware are being assessed as part of the ISS lifetime extension activities. Secondary structure is not being assessed. The phases and scope are listed below:

· Phase I (SSCN 9173) requests securing the FGB Dynamic Test Article and moving it to an environmentally controlled facility at KhSC.

· Phase II (SSCN 10513) requests extension of FGB structural life certification via testing of the FGB dynamic test article to 2020.

· Phase IIA (SSCN 11194) requests extension of the FGB docking mechanism structural life certification through 2020.

· Phase III (SSCN 11603) requests FGB non-replaceable and critical hardware service life to be extended through 2020.

· Phase III tasks include:

· Propulsion System Thermal and Atmospheric Control System functions

· Air Revitalization Subsystem (ARS)

· Soft Goods Testing

· Shell feed through and solar arrays seals

· Phase IIIA (SSCN 12283) requests for non-replaceable and critical hardware service life to be extended through 2028.

· Phase IIIA tasks include:

· Propulsion System, Thermal, and Atmospheric Control System

· Soft Goods Testing

· Shell feed through, solar arrays seals, and docking unit seals

· Komplast panel samples analysis

· Triol fluid analysis

· Recertify 3 FGB2 EPS ORUs

· Redesign and manufacture 3 FGB EPS ORUs

· Develop the repair and replace (R&R) procedure for FGB EPS ORUs (including thermal analysis)

· MMOD lifetime extension

1. Phase IIB (SSCN 13209) Request for Service Lifetime Extension of Functional Cargo Block (FGB).

1. Phase IIIB (CR 13209) Maintenance and Sustaining Plan for Electrical Power System (EPS) Orbital Replacement Units (ORU).

· Phase IV (CR 13079) will request development of sparing and maintenance for items which must be replaced to continue operations through 2028.

United States On-Orbit Segment The Primary Structural analyses approach was proposed to the program via SSCN 11686 to include the remainder of Phase I and subsequent Phase II. Phase III scope has been negotiated as part of the follow-on contract with the prime contractor.

The US primary structure will go through a number of analyses utilizing data from on-orbit sensors to reconcile the actual life used versus the predicted life to which it was formally certified. In many cases, the actual loading is less than the conservative design predictions. The analysis plan focuses on critical areas and once the current on-orbit used life and critical areas are established, the predicted operational plan will utilize the extrapolated loads data and spectra for the vehicle identifying any lifetime limitations of the USOS primary structure. Reconstructed data along with projected data based on assumptions provided will be applied to the analysis which will include updated thermal and optical properties. Updated fracture analyses will be performed utilizing an updated version of fracture mechanics software. Areas not meeting the requirement of four (4) service lives (as designated in SSP 30558, Fracture Control Requirements for Space Station) will be looked at further to determine possible approaches for analytical refinement. Analytical refinement may include fine-tuning of forcing functions, use of location-specific mechanical loads and spectra, time-consistent load combinations, and/or refinement of stress predictions and/or crack model selections.

If any areas cannot be shown by this analysis to have full capability through 2028, the lifetime limiting drivers will be identified and then additional mitigation activities will be initiated enabling capability through 2028. These may include but are not limited to the following:

· Potential changes in assumptions

· Potential changes to operations

· Testing (on-orbit or ground)

· Additional on-orbit instrumentation

· On-orbit inspections

· Thermal protections modifications (e.g., blankets, heaters, etc.)

· Modifications to structural hardware (e.g., doublers, reinforcements) Nodes 2 and 3 Nodes 2 and 3, originally designed and built by European partners at the European Space Agency (ESA), are the responsibility of NASA. The Node 2 structural lifetime certification will expire in October 2022 (TBR-1), and Node 3 structural lifetime will expire in February 2025 (TBR-2). Node 2 hardware service/operational lifetimes will expire in 2017 (TBR-3), and Node 3 hardware lifetimes will expire in early 2020 (TBR-4). Lifetime extension efforts for these modules and hardware beyond original certification are forward work to be coordinated between NASA and ESA.

Cupola The Cupola, originally designed and built by European partners, is the responsibility of NASA. The structural lifetime certification of the Cupola will expire in February 2025 (TBR-5). Service/operational lifetimes of Cupola hardware will expire in early 2020 (TBR-6). Lifetime extension efforts for the Cupola beyond original certification are forward work to be coordinated between NASA and ESA.

Permanent Multipurpose Module The Permanent Multipurpose Module (PMM) has been certified for an additional 10-year lifetime (2010 to 2020) by:

· Hardware recertification

· Assessment of rubber seals with an expired service life

· Execution of analyses

· Assessment of any issues relevant to parts and materials The seals facing with primary structure whose service life would have expired in 2017 were replaced and leak tested. PMM operational life through 2028 will need to be addressed as future work to be coordinated between NASA and Agenzia Spaziale Italiana (ASI). (TBR-7).

Secondary Structure Approach Secondary structure is defined as the internal or external structure which is used to attach small components, provide storage, and to make either an internal volume or external surface usable. Secondary structure attaches to and is supported by primary structure. Per SSP 30559, Structural Design and Verification Requirements, on-orbit secondary structure does not sustain significant applied on-orbit loads. Therefore, the only risk to be mitigated by examining externally-mounted secondary structure is a fatigue or fracture failure which would result in release of hardware that could result in a catastrophic hazard/failure (loss of life, vehicle or mission). Critical hazards of secondary structure are considered recoverable or manageable from a safety perspective and are therefore not assessed.

Externally-mounted hardware only (no Intra Vehicular Activity [IVA] hardware) fitting into the following categories are considered for secondary structural analysis with respect to lifetime extension evaluation:

· An on-orbit configuration such that one single structural failure would result in release of hardware

· Failure must pose an ‘immediate’ risk (e.g., no clips, support brackets, handrails, etc.)

· “Immediate” means not requiring additional steps to lead to a risk

· Must be a solid, structural installation

· No tethers, wire ties, temporary configurations, etc.

Additionally, off-nominal installations (e.g., Noncompliance Reports [NCRs], waivers) will be considered if the above criteria are applicable to the off-nominal configuration. Secondary structure was initially ground-ruled out of the ISS lifetime extension analyses, but later added for consideration of any potential catastrophic hazards. This approach was presented to the Vehicle Control Board (VCB) and approved for implementation August 1, 2011. Figure 3.1.2-1, Secondary Structure Analysis Approach, shows the screening process for secondary structure evaluation.

FIGURE 3.1.2-1 - SECONDARY STRUCTURAL ANALYSIS APPROACH

Analysis of the External Stowage Platforms (ESPs) main platform structure and attachment points will be performed as part of the Phase I primary structural analysis. Analysis of ELCs main platform structure and attachment points are included in SSCN 11967 scope. Analysis of unpressurized Flight Support Equipment (FSE) critical points will be performed also as part of the secondary structural assessment.

The Mobile Remote Servicer (MRS) Base System (MBS) Common Attach System (MCAS) is a NASA/Boeing responsibility. Boeing is responsible for v-guides and capture latches and will address these as part of the Phase I primary structural analysis with the Mobile Transporter assessment. NASA robotics will address the other MCAS components.

Critical Hardware & Non-Replaceable Hardware Approach Orbital Replacement Units The approach for addressing ORUs, or items easily replaceable, is being worked through the System Working Group (SWG) forum in an on-going effort. The SWG is a technical forum utilized regularly for reviews prior to presentations at the VCB. ISS technical teams are utilizing this forum as a technical review process for lifetime extension analysis results. Any technical issues which warrant further discussion or programmatic decision are then elevated to the VCB and/or the Avionics and Software Control Board (ASCB) or other programmatic board. Issues may proceed all the way up to the SSPCB for technical concurrence or programmatic decision/direction.

ORU hardware assessments for ISS lifetime extension are limited to critical items (Criticality 1 items). Rationale for not assessing Criticality 2 or 3 items is that for ORUs, failure of these items would present a recoverable scenario due to ability to replace the ORU. Sparing assessments will ensure sufficient capability is available to replace failed ORUs.

ORUs are analyzed utilizing the following criteria:

· The subsystem hardware should be evaluated and then categorized as acceptable to “run-to-failure” and then perform appropriate maintenance or R&R as appropriate, or “not recommended to run-to-failure” due to the nature or criticality of the potential failure modes;

· This evaluation focuses on the subsystem ORUs, recognizing that the module infrastructure (tubes, wires, fittings, etc.) is addressed separately;

· There are no violations to ISS operational requirements for fault tolerance or redundancy by continuing to operate ORUs beyond their certified life limit, therefore no waivers or CRs need to be processed.

If new life limiting features are identified, in addition to existing documented limited life items or preventive maintenance, forward work would then be established to identify the new plan for that component from an operations/sparing standpoint. Likewise, the items designated as “run-to-failure” will be coordinated with the logistics and maintenance team to be factored into future projections. Figure 3.1.3.1-1, ORU Hardware Review Process depicts the ORU hardware review process.

Elements of the ORU analysis include:

1. Assessment of the life certification as compared to the actual life.

2. Assessment of the criticality of the ORUs/components and any concerns with continuing to operate beyond the certification (utilizing existing Program documentation and databases such as Critical Item Lists [CILs], and Failures Mode and Effects Analysis [FMEA]).

3. Identification of hardware that was acceptable to “run-to-failure” or was in need of a plan for more detailed evaluation as unacceptable to run-to-failure.

4. Assessment of items with a criticality of 1S or 1R to determine if an action plan is required.

5. Consideration of established preventive maintenance, limited life items, and wear-out items (SA-06 documentation).

6. Review of safety noncompliance reports (NCR database) and FMEA.

7. Coordination with Materials and Processes (M&P) to determine if any life limiting concerns with non-metallic material (seals, valve seats, etc.).

8. Assessment of all items with a criticality of 1 or 1P to see if they are fracture critical. Any fracture critical items should be evaluated separately as described below.

FIGURE 3.1.3.1-1 – ORU HARDWARE REVIEW PROCESS

The ORU hardware review process was accepted by the SWG in April 2009. See example spreadsheet in Appendix D.

Non-Replaceable Hardware Non-replaceable hardware, due to their location, design, installation and function, are not intended for on-orbit R&R. Non-replaceable hardware will be assessed similarly to ORUs by screening of critical hardware, catastrophic failure effects, time and cycle limitations and identifying potential issues with run-to-failure. The program will address on a case-by case basis the non-replaceable hardware designated as not recommended to run-to-failure. Rather than plan for complex, laborious, and costly preventative replacement of this type of subsystem infrastructure, a work-around plan will be put into place in order to ensure the continued operability of that hardware. An example is to assess the capability to repair a wire insulation jacket or install an overlay cable, rather than spend resources to analyze wiring life. Hardware will be assessed in order of lifetime exceedance. This approach was accepted by the SSPCB on October 12, 2010.

Fracture Critical Hardware A streamlined approach for components requiring fracture critical assessment for ISS lifetime extension was developed and is based on conventional fracture analysis with relatively fast turn-around. Concurrence has been obtained from the Fracture Control Board, Vehicle Control Board, and the SSPCB on November 9, 2010.

Table 3.1.3.3-1 describes the conclusions of the fracture control plan for lifetime extension. This table refers to structural analysis. Housings of valves and QDs are of robust design and do not need structural integrity analysis. Other types of failures, such as seal leakage or failure to mate/demate, are assessed by subsystem teams to ensure no catastrophic failure modes and acceptability of run-to-failure. These conclusions hold as long as the original design and operational parameters/limitation are maintained. It will be up to the system team to elevate any excursions from the design and operational parameters. Items having exceedances will be assessed further on a case by case basis.

TABLE 3.1.3.3-1– NO ANALYSIS REQUIRED FRACTURE CRITICAL COMPONENTS

Flexible Metallic Lines (Flex Hoses)

connecting lines

· Stronger link in the chain

· Low fatigue impact by design

Quick Disconnects (QD)

Fittings

Switches

(1) As long as original design and operational parameters/limitation are maintained

For hard lines larger than and equal to 1.5 inches diameter, bellows, and pressure vessels analysis is required for ISS lifetime extension. Table 3.1.3.3-2 provides more details.

TABLE 3.1.3.3-2 – ANALYSIS REQUIRED FRACTURE CRITICAL COMPONENTS

· Typically designed to 10 yr. operation life

· Analysis required using Actual + Projected usage spectra

· Fatigue or Fracture analysis

(welded, formed, etc.)

Lifetime extension requires analysis on a case by case basis

Similar considerations as primary structure Lifetime extension requires rigorous analysis on a case by case basis

(1) Limited number of components

Subsystem teams are responsible for identifying components for analysis and providing the Structures and Mechanisms team with a preliminary assessment of criticality of failure including the component part number and usage data. Subsystem teams will also raise any flags for issues or forward work if discovered in the preliminary assessment. Any issues flagged previously are brought forth to the ISS Program for discussion and forward planning to mitigate them.

Figure 3.1.3.3-1 shows the Subsystem Level Assessment Plan.

Identify fracture critical hardware Gather actual pressure vs.

time usage data OK to run to failure Develop TBD appropriate assessment process Continue use thru 2028 N N Y Y Y Y Passed N N Send to Structural Integrity For Assessment Is Failure Significant?

Any Non metallic parts?

M&P evaluation meets 2028?

Raise flag and determine appropriate action Component of a pressurized system?

Document per Program guidelines Did not pass Ever exceeded MDP during its life?

Y N Projected 2028 Ops exceed original design?

N Y Tested to SSP 30559 Safety factors ?

N Y Special evaluation needed?

Y N

FIGURE 3.1.3.3-1 – SUBSYSTEM LEVEL ASSESSMENT PLAN

Figure 3.1.3.3-2 depicts the Structural Analysis Assessment Plan which is performed upon receipt of information from the Subsystem teams. The Structures team will perform a comprehensive assessment of the various types of pressure system components. No analysis is required for hard lines less than 1.5 inches diameter, or for all flexible hoses, valves, and fittings (considered indefinite life components). Analysis is performed for hard lines greater than and equal to 1.5 inches diameter per SSPs 30558 and 52005. Pressure vessels will always be analyzed to safe life requirements. Bellows will be assessed on a case by case basis (may need special analysis) (TBR-17).

FIGURE 3.1.3.3-2 – STRUCTURAL ANALYSIS ASSESSMENT PLAN FOR FRACTURE CRITICAL ELEMENTS

Government Furnished Equipment Government Furnished Equipment (GFE) is being assessed through a process similar to the ORU and non-replaceable hardware. The nature of this equipment is somewhat different as it is usually not permanent hardware on ISS. All limited lifetime or limited certification items are being reviewed. Items with Criticality of 1 or 2 are being reviewed for impact of further operations beyond 2015. Criticality 3 items are not being assessed since their failure does not pose a critical or catastrophic impact to life or mission. Crew preference and personal items are not being reviewed. Crew preference and personal items are categorized as Criticality 3 and considered benign consisting of clothing, hygiene materials, office supplies, and other personal items which usually transport to orbit and back with a specific crew. If any items are found to be fracture critical, they will follow the fracture critical assessment established for lifetime extension. For items designated as run to failure, an administrative update of the Government Certification Approval Request (GCAR) will be performed after the technical evaluation has been completed by the subsystem team and accepted by the System Working Group. Items deemed as limited life will follow the standard limited life processes set up and managed within the ISS program. This approach was accepted by the SSPCB on October 12, 2010.

Payload Facility Assessments Payloads, or experiments, have a defined time of execution on ISS. Most of the hardware associated with the experiment are considered consumables and/or samples. The rack hardware or facilities which support the experiments are permanent/near permanent and will be assessed from a risk standpoint. Individual payloads will not be assessed with respect to ISS lifetime extension. Facility class payloads are assessed (experiments and subracks are not analyzed). Standard payload outfitting equipment (i.e., smoke detectors, Internal Thermal Control System [ITCS] support, vacuum line, Node 2 line) will be addressed via the subsystem hardware teams in their ORU assessments and/or non-replaceable hardware assessments. Expedite the Processing of Experiments to Space Station (EXPRESS) and Derivatives ORU sparing analysis will be performed by the Logistics and Maintenance (L&M) team as part of the overall ISS sparing assessments. Figure 3.1.3.5-1 shows the payload facilities analysis process.

FIGURE 3.1.3.5-1 – PAYLOAD FACILITIES ASSESSMENT PROCESS

Utilization facility hardware that may have catastrophic failure effects or may support critical functionality for utilization will be reviewed for life limitations. Like the ORU and non-replaceable hardware, any time or cycle limitations will be identified and addressed. Materials assessments will also be performed as needed. On-orbit pressure systems, non-replaceable hardware, spares, limited life or limited cycle hardware will be reviewed for impact. Ground facilities integral in supporting on-orbit operations will be reviewed for impacts beyond 2015. Action plans will be developed and documented for components that are not deemed as safe to “run-to-failure” on-orbit. Table 3.1.3.5-1 lists the facilities which will be assessed.

TABLE 3.1.3.5-1 – PAYLOAD FACILITIES FOR ASSESSMENT

ExPress Carrier Avionics (ExPCA) Expedite the Processing of Experiments to Space Station (EXPRESS) 1 Human Research Facility (HRF) 1&2 Microgravity Sciences Glovebox

(MSG)

Window Observational Research Facility (WORF) Material Science Research Rack (MSRR) Minus Eighty Laboratory Freezer for ISS (MELFI) 1 General Laboratory Active Cryogenic ISS Experiment Refrigerator (GLACIER) all Fluids Integrated Rack (FIR) Combustion Integration Rack (CIR)

Facility hardware with a critical failure effect and/or items not having time or cycle limitations will not be assessed (only catastrophic failure effects will be assessed). The rationale behind this is that any critical failures may result in loss of science, but the vehicle and systems would be recoverable due to redundancy from an overall ISS functional perspective. This approach was accepted by the SSPCB on October 12, 2010.

Individual payloads/experiments won’t be assessed. The assessment of payload facilities will review only catastrophic failure effects. Critical failures will not be assessed as, although it would result in loss of science, the vehicle and systems would be recoverable due to redundancy of the overall ISS. Table 4-1 documents the current status of the assessment for each element.

Robotics Assessments From a robotics perspective, NASA is responsible for the Mobile Transporter (MT) and Robotics Work Station (RWS). ORUs associated with these systems will be assessed per the ORU assessment criteria. As for structural analysis of the MT, it will be included as part of the USOS structural lifetime assessments.

The Canadian Space Agency (CSA) is responsible for the Mobile Servicing System (MSS) that consists of the following components: the Space Station Remote Manipulator System (SSRMS), the MBS, and the Special Purpose Dexterous Manipulator (SPDM). Section 3.2.4 describes the CSA approach to analyzing the MSS hardware. This plan was presented to the Mobile Service System Integration Panel (MIP) and concurred with on September 20, 2011. The MIP is a board co-chaired by the ISS Program Integration Office and the Canadian Space Agency.

Hardware Sparing and Functionality Assessments The purpose of the functional availability sparing risk assessment is to identify functions that may be at risk, and within functions, identify ORUs that contribute to the risk, and provide function and ORU risk data to the program. Such decisions could include: Original Equipment Manufacturer (OEM) closeouts or extensions, retention of repair capability, spares procurement, and budget planning. Functional availability and sparing assessments are performed on an annual basis. The process is defined in the January 11, 2007 presentation to the ISS Program Manager. Figure 3.1.4-1 depicts the logistics support requirements determination process.

FIGURE 3.1.4-1 – 2020/2028 LOGISTICS SUPPORT REQUIREMENTS DETERMINATION PROCESS

Systems teams review various hardware data including Problem Reporting and Corrective Actions (PRACAs), Failure Investigation and Action Reports (FIARs), NCRs, and on-orbit performance. The teams evaluate re-design options, trades and workarounds. Functionality targets are defined through the targeted timeframe 2020/2028. The L&M team looks at top level spares recommended in the past, vendor availability, ORU and parts availability, repair status, and works with supportability modeling tools. The Reliability and Maintainability (R&M) team updates the Mean Time Between Failure (MTBF) data. All data is taken into account in the function by function review.

Updated function targets and associated diagrams are produced. Assumptions and ground rules are documented as well as risk level definitions and criticality considerations. From this the strategic maintenance functional availability analysis is performed. Items are categorized by low, moderate, or high risk from a supportability perspective. Quantity recommendations are provided for varying levels of support and a cost assessment is performed. The process is iterated and various programmatic operational constraints are also taken into account.

Finally, the process is completed by proceeding with updated spares procurement and plans. When assumptions, requirements, or other factors change the assessment is recomputed. This is usually an annual activity.

The ISS PRA team will provide support to the L&M group by performing analysis for sparing confidence levels through end of life. The team will also assist the L&M group by performing analyses to determine which ISS components will experience wear out due to lifetime extension. This information would be used by the L&M group in their sparing analysis for the ISS.

Safety and Mission Assurance Assessments Items with potential to cause catastrophic and critical hazardous failure effects and critical functions will be reviewed. The Safety and Mission Assurance (S&MA) approach will provide adequate and independent review to identify any change in the ISS risk posture to safely extend the lifetime of the ISS through 2028.