sme initiative materials and processes division esa/estec/tos-qm sheet1 sme initiative course...

Materials and Processes DivisionESA/ESTEC/TOS-QM

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SME INITIATIVE COURSE

MATERIALS

MATERIALS AND PROCESSES DIVISION

ESTEC


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One question frequently asked is “Why does ESA not have a preferred materials list whereas such a list does exist for electronic components?”

The reason for this is best summarised by the relationship:

Material + Process Environment Application

In other words a material can only be considered together with the associated process and the final application. To complicate matters further the effects of the environment (manned or unmanned, LEO or GEO etc.) have to be considered since these can significantly affect the suitability of the application

INTRODUCTION


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Example 1

For example:

Solithane 113 + Process PCB Conformal Coating

(Polyurethane) (24 hr 65C)

This combination is widely used in spacecraft application.

However for manned space applications this cannot be used since solithane,

in common with most polyurethanes, is flammable


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Example 2

Sylgard 184 + Process PCB Conformal Coating

(Silicone) (RT cure)

This combination is used for manned space applications.

However for applications exposed to space vacuum this cannot be used since

sylgard does not meet the outgassing requirements.

Materials are therefore approved in conjunction with the associated process, the application and the associated environment.

In other words, approval is granted per project.


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SUBJECT :

THE REQUIREMENTS RELATED TO MATERIALS, MECHANICAL PARTS AND PROCESSES.


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The following section presents the requirements for PMP. However the actual requirements for a particular project depend on several factors, e.g.

1. Type of spacecraft (manned or unmanned)

2. Spacecraft orbit (LEO, GEO, polar etc.)

3. Complexity (satellite, payload, etc.)

4. Duration of space exposure (x years, y days, etc.)

The requirements will therefore be specified as part of the contract either in the statement of work or in the PA plan.


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PSS Specifications Related to PMP

PSS-01-70 - Issue 4 - Jan 94. Material, mechanical-part and process selection and quality control for ESA space systems and associated equipment.

This specification establishes the detailed requirements for the selection and control of materials, mechanical parts and processes for space systems and associated equipment in which the use of materials etc. with specific reliability and quality requirements is mandatory.

PSS-01-700- Issue 2 - Aug 93. The technical reporting and approval procedures for materials mechanical parts and processes.

This specification provides details concerning the documentation requirements and the procedure relevant to obtaining ESA approval for the use of PMP in the fabrication of space systems associated equipment.


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ECCS Specification Related to PMP

ECSS-Q-70A-April 96 Space Product Assurance - Materials, Mechanical Parts and Processes.

The purpose of this standard is to define the requirements and statements applicable to Materials, Mechanical Parts and Processes to satisfy the mission performance requirements. This standard also provides details concerning the documentation requirements and the procedures relevant to obtaining approval for the use of PMP in the fabrication of Space Systems and associated equipment.

This documentation is currently under revision and issue B will include the documentation Requirements presently given in PSS-01-700.

In addition many of the lower level PSS Specification (PSS-01-7XXX series) are being replaced by ECCS Specification (ECSS-Q-70-XX series).


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European Co-operation for Space Standardisation (ECSS) (1)

For materials and processes the situation is presently as follows:

1. ESA PSS-01-70 has been replaced by ECSS Specification ECCS-Q-70A

2. An additional twelve specifications, based on the PSS-01-7xx Series, have been issued as ECSS Specifications

• ECSS-Q-70-04A Thermal Cycling test for the Screening of space materials and processes

• ECSS-Q-70-07A Automatic machine wave soldering• ECSS-Q-70-08A The manual soldering of high reliability electrical connections• ECSS-Q-70-13A The Peel and Pull Off Strength of Adhesives• ECSS-Q-70-25A The Application of Aeroglaze Z306• ECSS-Q-70-29A Offgassing Testing of Materials• ECSS-Q-70-30A Wire-wrapping of high reliability electrical connections• ECSS-Q-70-33A The Application of Thermal Coating PSG120FD• ECSS-Q-70-34A The Application of Aeroglaze H322• ECSS-Q-70-35A The Application of Aeroglaze L300• ECSS-Q-70-36A Materials selection for controlling stress corrosion• ECSS-Q-70-37A Test method for stress corrosion cracking


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European Co-operation for Space Standardisation (ECSS) (2).

3. An additional six specifications are in various stages of ECSS review.

• ·ECSS-Q-70-02 Outgassing Testing of Materials

• ·ECSS-Q-70-21 Flammability Testing

• ·ECSS-Q-70-22 Limited Shelf Life Materials

• ·ECSS-Q-70-26 The Crimping of High Reliability connections

• ·ECSS-Q-70-28 Repair and modification of PCB assemblies

• ·ECSS-Q-70-38 High reliability soldering for surface mount and mixed technology PCBs


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THE REQUIREMENTS

1. GENERAL The Contractor shall establish and implement throughout the duration of the contract a PMP programme which ensures full compliance to

PSS-01-70/ ECSS-Q-70A.

2. PLANNING AND DOCUMENTATIONThe Contractor shall ensure that the PMP programme is

thoroughly planned and documented. Particular emphasis shall be placed on Critical PMP.

3. PROGRAMME PLAN The Contractor shall prepare a PMP Selection and Control Plan which describes the programme and procedures he will adopt for

compliance with the requirements of PSS-01-70/ ECSS-Q-70A. It shall be the Contractor's responsibility to ensure that all sub-contractors PMP programmes are consistent with his Plan. Particular attention shall be paid to specific Project requirements for PMP, their control and interfaces with sub-contractors activities.


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THE REQUIREMENTS(Continued)

4. CLEANLINESS/CONTAMINATION CONTROL

The Contractor shall establish and maintain an effective contamination and cleanliness-control programme in compliance with Project requirements according to PSS-01-201 (to be superceded by ECSS-Q-70-01).

• Cleanliness-requirement specification (chemical and particle);

• Cleanliness-control plan;

• Cleanliness-monitoring procedures/methods.


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GENERAL POINTS

One person should be nominated who is the contact point for all PMP matters. He / She is responsible for the following:

• Preparation of the PMP plan in response to requirements imposed by the higher level

• Ensuring that PMP used within his / her own company and by lower level contractors meet the requirements

• Preparation of applicable PMP lists

• Identification of critical PMP

• Performance of audits (internal, external), particularly related to critical processes

• Participation to MRBs related to PMP

• Monitoring of evaluation / validation or qualification programmes related to PMP

• Interfacing with safety and QA where relevant


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PMP which cannot be considered either space proven or standard/established shall be subjected to an evaluation programme in order to assess their suitability for the intended application. This programme and subsequently its result shall be submitted to ESA.

1. Thermal Vacuum Products considered for use in space systems shall have their outgassing properties assessed by thermal vacuum tests according to PSS-01-702 (to be superceded by ECSS-Q-70-02).

2. Thermal Cycling Products which are likely to be subjected to thermal stresses shall have their thermal cycling properties assessed as per ECSS-Q-70-04A.


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3. Radiation Products which will be exposed to particle/UV radiation shall be assessed to determine their ability to withstand the type and degree of radiation

dosage expected during the mission. Tests are specified in PSS-01-706.

4. Stress Corrosion Products intended for structural applications and likely to be exposed to long term terrestial storage, or flown on the STS, or used in launchers shall possess a high resistance to SCC. Structural products of a metallic nature shall be selected from the preferred list in Table 1 of ECSS-Q-70-36A.

Where no data exists testing shall be performed as per ECCS-Q-70-37A.


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5. Flammability Products considered for use in unmanned spacecraft to be launched by the STS and manned spacecraft (including those of the spacecraft itself, stored equipment or payload/experiments) shall be evaluated for flammability resistance in the most hazardous environment. Flammability testing is described in PSS-01-721 (to be superceded by ECSS-Q-70-21A).

6. Offgassing and Toxic analysis

All products considered for use in the crew compartment of manned spacecraft shall be evaluated for offgassing and odour.

Samples of each product shall be tested according to ECSS-Q-70-29A.


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7. Atomic Oxygen All products considered for use on the external surface of spacecraft intended for low-orbit operations shall be evaluated for their

resistance to atomic oxygen erosion. Proposed tests shall be subject to ESA approval.

8. Supplementary tests The Contractor shall review his PMP programme for particular Project requirements and add any other test as relevant.

These tests are subject to ESA approval.


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MATERIAL/MECHANICAL PART ENGINEERING

1. SELECTION The Contractor shall be responsible for the selection of materials / mechanical parts and for demonstrating that they are capable of meeting the operating, environmental, physical, chemical, safety, quality and reliability conditions defined in the relevant specifications and in the contract.

2. SELECTION OF SPACE-PROVEN MATERIALS

Well known materials/mechanical parts for which test data applicable to the space environment are available or which have been previously used in space, or similar, applications shall be selected wherever possible. However each material/mechanical part and its applications for a given Project shall be considered separately.

3. SELECTION OF OTHER MATERIALS

Request for approval (RFAs) of material/mechanical parts which do not meet the requirements of 2) above shall be submitted to ESA. The format and content of the RFA is given in PSS-01-700. This can be modified by a Project (subject to approval) if the specific requirements of the Project make this necessary.


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MATERIAL/MECHANICAL PART ENGINEERING (Continued)

4. DECLARED MATERIAL LIST (DML)/DECLARED MECHANICAL PARTS LIST (DMPL)

The Contractor shall establish a consolidated DML and DMPL of all items used in the system.

Notes: The project may decide not to consolidate the lists but to compile an assembly of Lists per Configuration item.

The Project may decide not to require a separate DMPL. In this case the items are added to the DML;

The format and content of the DML/DMPL is given in PSS-01-700. This can be modified by a Project (subject to approval) if the specific requirements of the Project make this necessary.

Amendments to the DML/DMPL shall only be implemented through established change procedures.


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MATERIAL/MECHANICAL PART ENGINEERING (Continued)

5. SPECIFICATIONS/STANDARDS

Each type of material/mechanical part used by the Contractor and listed in the DML/DMPL shall be covered by a specification or standard.

6. NON-CONFORMANCES

Non-conforming materials/mechanical parts found during incoming inspections, assembly or test shall be dispositioned in

accordance with ECSS-Q-20A.


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PROCESS ENGINEERING

1. SELECTION The Contractor shall be responsible for the selection of processes and for demonstrating that they are capable of meeting the requirements as

defined in the applicable Specifications and in the contract. The Contractor and sub-contractor shall plan and enforce an effective process control programme. ESA reserves the right to audit critical processing lines.

2. STANDARD/ESTABLISHED PROCESSES

Standard processes shall be selected whatever possible. Critical processes, unless performed in accordance with PSS-

01-7XX/ECSS-Q- 70-XX series documents shall require further identification and approval before use.


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PROCESS ENGINEERING(Continued)

3. NONASSESSED PROCESSES

RFAs for processes for which there is no known previous history shall be fully justified and be subjected to an evaluation programme. The process identification and approval documents, defined in PSS-01-700, shall be submitted to ESA.

4. DECLARED PROCESSES LIST (DPL)

The Contractor shall establish a DPL of all processes used in the programme. The format and content of such a DPL is

given in PSS-01- 700. Amendments to the DPL shall be implemented only through established change procedure.


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5. PROCESS SPECIFICATION/STANDARD

Each process shall be covered by a process specification or standard. Maximum use shall be made of existing ESA Specifications/standards and ESA approved Specifications/standards produced by international organisations and national agencies.

6. PROCESS WORKMANSHIP STANDARDS

The Contractor shall provide detailed workmanship standards for processes to aid operators and inspectors in the

establishment of accept/reject criteria.


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7. CRITICAL PROCESSES

Critical Processes shall be subject to stringent controls in form of documentation, QA supervision (MIP, KIPs etc). and

final inspection/test. Critical processes shall be defined by the Contractor in the early phase of the contract. (see later for a definition of Critical Process)

8. NON CONFORMANCES

Any unsatisfactory performance or non conformance which is observed shall be dispositioned in accordance with ECSS-Q-20A.

9. TRAINING The Contractors shall establish a training programme for all critical process operators and inspectors (e.g.. PSS-01-748).


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SUBJECT: THE DOCUMENTATION REQUIREMENTS


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DECLARED MATERIALS LIST

ESA PSS-01-700 Issue 2 (August 1993)


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CONTENTS OF THE DECLARED MATERIALS LIST GROUPS:

Materials are classified into 20 groups depending on their type or their main use.

1. Aluminium and aluminium alloys

2. Copper and copper alloys

3. Nickel and nickel alloys

4. Titanium and titanium alloys

5. Steels

6. Stainless steels

7. Filler metals: welding, brazing, soldering

8. Miscellaneous metallic materials

9. Optical materials

10. Adhesives, coatings, varnishes


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CONTENTS OF THE DECLARED MATERIALS LIST GROUPS (Continued):

11. Adhesive tapes

12. Paints and inks

13. Lubricants

14. Potting compounds, sealants, foams

15. Reinforced plastics

16. Rubbers and elastomers

17. Thermoplastics (non adhesive tapes, foils (MLI), …)

18. Thermoset plastics

19. Wires and cables (for materials aspects only)

20. Miscellaneous non metallic materials (ceramics …)

If for a given project it is deemed necessary and approved by ESA to create new groups, these shall bear numbers over 20.

Primers shall be classified in the group of their associated components.


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CONTENTS OF THE DECLARED MATERIALS LIST COLUMNS:

The materials list consists of 10 columns which shall be completed as indicated below. Furthermore, similar materials shall be grouped together as specified above. If a particular item does not apply, write N.A. (Not Applicable).

COLUMN 1: Item number

Identification number in each group. One only per material type. Does not change during the life of the materials list (sub-items permitted when deemed necessary).

COLUMN 2: Commercial identification

Trade name and number (to be completed in full) e.g. “ARALDITE AV 100”. Correct and standard designation.


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CONTENTS OF THE DECLAREDMATERIALS LIST COLUMNS (Continued)

ESA has chosen:

* Trade name + number. For example, “ARALDITE AY 105”

* If no trade name exists, then the manufacturer’s name plus number are entered;

e.g. “SCHOTT BK7”

* In the case of metal alloys, the AA system is recommended for aluminium alloys, and the

AISI system for steels; for other metals or alloys, the main constituent will be entered first

except in the case of a traditional name (e.g. brass or bronze).

For each material as designated above, a unique item number shall be given. If several lines

are used for different applications and/or processing, sub-item numbers shall be added.

COLUMN 3: Chemical nature and type of product

Example: epoxy resin, polyurethane adhesive, or Ti, 6 Al, 4V alloy.


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COLUMN 4: Procurement information

Manufacturer / supplier: name of the manufacturer and name of the supplier if different.

Specification: reference of the procurement specification with, if considered useful, issue and revision. It may be replaced by a national specification number if this exists and makes source of procurement irrelevant.

COLUMN 5: Processing parameters (summary):

Give as relevant: mixture proportions, cure temperature, special cleaning agent, surface treatment, thermal treatment, temperature, etc..

NOTE: Specification number is required, but not sufficient for ESA purposes.

COLUMN 6: Use and location

Indicate in what subsystems, box or item the material is used and whether it acts as structural element, thermal control, electrical insulation etc. as relevant.


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COLUMN 7: Environmental code

Radiation/UV/ATOX (1)(R)

Ambiance(A)

Temperature (2)(T)

G = GeostationnaryL = Low orbitB = Radiation beltsI = Interplanetary

S = outside shadowL = outside light

V = VacuumH = HermeticM = MannedE = Elevated pressure

1 = 0 to 100 K2 = 101 to 200 K3 = 201 to 300 K

“““

(1) For materials inside the spacecraft, choose a letter from the left-hand column. For materials on the surfaceof the spacecraft, combine this letter with “L” or “S”.

(2) Thermal cycling to be indicated by two values, e.g. 3/5.(3) “RT” can be accepted as a code between 283 K (10 C) and 313 K (40 C).

Materials which are at a boundary between environments shall be described by two sets of codes.


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COLUMN 8: Size code

AREA

VOLUME

MASS

A (cm2)

V (cm3)

W (g)

0 = 0 < 11 = 10 < 102 = 10 < 1003 = 100 < 1000etc.

Choose an alphanumeric combination from the above mentionedtable, e.g. A5 or V2 or W3.


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COLUMN 9:

All the codes of Column 9 shall be relevant for the project concerned, which implies that they refer to validated data applicable to this project (not too old, same processing, same composition, QC tests run on the same procured lot, etc.).

Reference of test report and relevant test result code to be given in Subcolumn 9.1.

SUBCOLUMN 9.1.

Outgassing (OUT):

P - The material passed the outgassing test detailed in ESA PSS-01-702.

Reference of test report to be given in Subcolumn 9.2.

F - The material failed. Waiver reference in Subcolumn 9.2.

U - Materials of which outgassing characteristics are unknown.


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Stress Corrosion Cracking (SCC):

A - The material is known to have a high resistance to SCC.

Table I document ECSS-Q-70-36A.

B - Table II and III document ECSS-Q-70-36A.

Justification for approval (test reference) stated in Subcolumn 9.2 (generally making reference to ECSS-Q-70-36A).

U - Materials and / or weldments for which SCC characteristics are unknown:

An SCC evaluation form is required, based if necessary on tests (see ECSS-Q-70-37A).

Corrosion (Corr.):

A - The material does not require a surface treatment or coating for its intended application, otherwise it shall be rated B.

B - Details of surface treatment to be given in Column 5.


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Flammability (Flamm.) (if applicable):

P - The material passed the requirements of document ESA PSS-01-721.

F - The material failed the test of documentation ESA PSS-01-721 in the applicable atmosphere. Waiver reference in Subcolumn 9.2.

U - Materials of which characteristics are unknown:

Offgassing (OFF) (if applicable):

P - The material passed the requirements of document ECSS-Q-70-29A.

F - The material failed : waiver reference in Subcolumn 9.2.

U - Materials of which offgassing characteristics are unknown.


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SUBCOLUMN 9.2: Justification for approval

The purpose of this Subcolumn is to enter any additional information that may be necessary in order to achieve customer approval. This information is reference of the Requests For Approval, reference of justificatory file for materials approved for other space or aeronautical programmes meeting the specific needs of the programme, reference of the evaluation report or waivers etc.. These documents must be made available to ESA on request.


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SUBCOLUMN 9.3: Approval status of the Contractor

A: Approved - All Materials classified A may be used without restriction.

Y: Approved with restriction - These materials require the preparation of QC test specimens or a treatment before use: potting, coating, test specimens …

W: Approved with waiver - These materials do not meet the requirements but are used for functional reasons. The use of such materials shall be

reduced to a minimum. All the waivers shall be approved by ESA. The waiver number shall be entered in Subcolumn 9.2.

P: Pending a decision - Materials for which an evaluation report or a waiver is awaiting the Contractor’s provisional or definitive approval.

O: Open - New materials or materials for which investigations and qualification are in progress.

D: Deleted - This classification is used for a material which is no longer used.


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COLUMN 10: ESA approval and comments

This column will be completed by ESA.


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DECLARED PROCESS LIST



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CONTENTS OF THE DECLAREDPROCESS LIST GROUPS

Processes shall be classified into 17 groups:

1. Adhesive bonding

2. Composite manufacture

3. Encapsulation / moulding

4. Painting / coating

5. Cleaning

6. Welding

7. Crimping / Stripping / wire wrapping

8. Soldering / Brazing

9. Surface conversion treatments

10. Plating


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CONTENTS OF THE DECLAREDPROCESS LIST GROUPS (Continued)

11. Machining

12. Forming

13. Heat treatment

14. Special fabrication: processes developed specifically for the programme

15. Marking

16. Miscellaneous processes

17. Inspection procedures



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CONTENTS OF THE DECLARED PROCESS LIST COLUMNS

The process list consists of 10 columns which shall be completed as indicated below. If a particular item does not apply, write N.A. (Not Applicable).

Processes which apply to only one material (one Declared Materials Lists item) and which are sufficiently defined in column 5 of the Declared Materials Lists should not appear in the Declared Processes List (unless they are critical).


Sequential item number in each group of the Declared Processes List. One only per process type. Does not change during the life of the processes list.

COLUMN 2: Process identification

Process name, title, clear identification, etc. Correct and standard identification.


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CONTENTS OF THE DECLAREDPROCESS LIST COLUMNS (Continued)

COLUMN 3: Specification

Specification number (whether national, ESA, company in house etc.) and issue status. Only the contractor’s / subcontractor’s specifications that can be physically transmitted to ESA for review purposes are to be entered on the Declared Processes List.

COLUMN 4: Process description

Brief description of the process.


Define location in the spacecraft / equipment, use, and purpose of process for the spacecraft.

COLUMN 6: Manufacturer’s name

Name / abbreviation (the one who applies the process).


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CONTENTS OF THE DECLAREDPROCESS LIST COLUMNS (Continued)

COLUMN 7: Item in materials list or mechanical parts list

Corresponding materials list or mechanical parts list item number.

COLUMN 8: Criticality of process

Indicate here whether process is critical or noncritical. In the case of a critical process, add reason for criticality.

NOTE: for critical processes other than those performed exactly to an ESA PSS-01-7XX series specification, this form is to be supplemented by a Process Request for Approval (RFA / Process) (in the same Annex).


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CRITICAL PROCESS

DEFINITION PRESENT INPSS-01-700

PRESENT INECSS-Q-70A

1 A process that in the case of failure can adverselyaffect the performance or destroy a major part orfunction of the space system

YES NO

2 The quality of which cannot be assessed solely byexamining the end product

YES NO

3 A process that has caused problems previously YES YES4 Where an ESA specification is available but is not

being implementedYES NO

5 A process with which the contractor in charge of ithas had no previous experience

YES YES


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The purpose of this is to enter any additional information that may be necessary in order to achieve customer’s approval. This information comprises reference and issue of the RFA / Approval, processes justification file, evaluation reports and waivers. These documents must be made available to ESA on request.

SUBCOLUMN 9.2: Contractor’s approval

The Prime contractor shall complete this subcolumn and by doing so confirms that:

- the line indications are correct and complete

- the process has passed all applicability tests (including quality control testing).

A: Approved - The validation is approved by the Contractor

W: Approved with a waiver - The use of such processes shall be reduced to a minimum. All the waivers shall be approved by ESA. The waiver number shall be entered in Subcolumn 9.1.


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P: Pending a decision - processes for which a validation report or a waiver is awaiting the Contractor’s decision.

O: Open - New process or process for which investigations and qualification are in progress.

D: Deleted - This classification is used for a process which is no longer used.

Where no approval can be granted, the Process Request for Approval (RFA / Process) shall be submitted to ESA for approval if not yet available. ESA may request a copy of the process specification and an audit of the process.

COLUMN 10: ESA approval



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DECLARED MECHANICAL PARTS LIST



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CONTENS OF THE DECLARED MECHANICAL PARTS LIST GROUPS:

Mechanical parts shall be classified into 11 groups:

51. Spacing parts (washers, spacers, …)52. Connecting parts (bolts, nuts, rivets, inserts, clips, …)53. Bearing parts (ball-bearings, needle bearings, …)54. Separating parts (pyrotechnics, springs, cutters, …)55. Control parts (gears, …)56. Fluid handling parts (diffusers, …)57. Heating parts58. Measuring instruments (gauges, thermocouples, …)59. Optical passive equipment60. Magnetic parts

61. Other parts


Items which should appear in the EEE parts list should not be repeated here (e. g. motors, heaters, some valves, thermostats, relays, transformer coils, solenoids, ferrite cores, …).


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CONTENTS OF THE DECLARED MECHANICAL PART LIST COLUMNS:

The mechanical parts list consists of 10 columns which shall be completed as indicated below. If a particular item does not apply, write N.A. (Not Applicable).


Sequential item number in each group of list. One only per mechanical part type. Does not change during the life of the mechanical parts list.

COLUMN 2: Commercial identification

As required:

* type and number

* specification number (whether national, ESA, company in-house, etc.) and issue status.

This document must be available for sending to ESA on request.

* material


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CONTENTS OF THE DECLARED MECHANICAL PART LIST COLUMNS (Continued)

COLUMN 3: type of part

Use a standard nomenclature, in order to ensure correct grouping of similar parts, e.g.:

valve, one way

valve, two way

and not one-way or two-way valve.

COLUMN 4: Procurement information

As for Declared Materials Lists:

* Manufacturer / supplier: name of the manufacturer and name of the supplier if different.

* Specification: reference of the procurement specification with issue and revision. It may be replaced by a national specification number if this exists and makes source of procurement irrelevant.


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COLUMN 5: Elementary function, main characteristics

* function to be ensured by the mechanical part

* main characteristics: e.g. number of revolutions per minute for a ball bearing


Indicate in which subsystems, equipment or box the mechanical part is used + subcontractor’s name / abbreviation.


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COLUMN 7: Environmental code

As for DML:

Radiation/UV/ATOX (1)(R)

Ambiance(A)

Temperature (2)(T)

G = GeostationnaryL = Low orbitB = Radiation beltsI = Interplanetary

S = outside shadowL = outside light

V = VacuumH = HermeticM = MannedE = Elevated pressure

1 = 0 to 100 K2 = 101 to 200 K3 = 201 to 300 K

““

etc.

(1) For materials inside the spacecraft, choose a letter from the left-hand column. For materials on the surfaceof the spacecraft, combine this letter with “L” or “S”.

(2) Thermal cycling to be indicated by two values, e.g. 3/5.(3) “RT” can be accepted as a code between 283 K (10 C) and 313 K (40 C).

Parts which are at a boundary between environments shall be described by two sets of codes.


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COLUMN 8: Criticality and hazards

Mark here all parts participating in a safety-critical and / or reliability-critical function.


The purpose of this subcolumn is to enter any additional information that may be necessary in order to achieve customer approval. This information is reference and issue of the Request For Approval, reference of justificatory file for parts approved for other space or aeronautical programmes meeting the specific needs of the programme and waivers etc. These documents must be made available to ESA on request.


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SUBCOLUMN 9.2: Contractor’s approval

A: Approved - All Mechanical parts classified A may be used without restriction.

W: Approved with waiver - These mechanical parts do not meet the requirements but are used for functional reasons. The use of such mechanical parts shall be reduced to a minimum. The waiver number shall be entered in Subcolumn 9.1.

P: Pending a decision - mechanical parts for which an evaluation report or a waiver is awaiting the Contractor’s provisional or definitive approval.

O: Open - New mechanical parts or mechanical parts for which investigations and qualification are in progress.

D: Deleted - This classification is used for a mechanical part which is no longer used in spacecraft.

COLUMN 10: ESA approval and comments



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THE REQUEST FOR APPROVAL (RFA)

This is a document with which the user asks the customer for permission to use a critical mechanical part, material or process.

Two issues of this are required:

• Issue 0 - Request accompanied by the evaluation or validation / qualification programme;

• Issue 1 - Request accompanied by the validation or qualification results.

(Definition from ECSS-Q-70B Draft)


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THE RFA (Continued)

For critical PMP the supplier shall submit an RFA, suitable formats are given in PSS-01-700 and ECSS-Q-70B (Draft). The initial issue (Issue 0) of the RFA for provisional approval should be provided as early as possible and not later than PDR. This approval gives agreement to perform the evaluation / validation / qualification programmes and allows the PMP to be included in the design process. Definitive approval is only given after successful completion of the relevant test programme; at which time the RFA is updated with the relevant test report references etc and reissued (Issue 1) in its final form. This should be complete prior to CDR such that the material can be used in flight hardware construction.


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THE REQUEST FOR APPROVAL (RFA), THE REQUEST FOR DEVIATION (RFD) AND THE REQUEST FOR WAIVER (RFW)

There is, unfortunately, much confusion surrounding the use of the above terms. Strictly speaking they should be used as follows:

RFA - Document which asks customer permission to use a critical part, material or process.

RFD - Document which asks customer permission to use a part, material or process which does not meet one or more of the specified requirements (e.g. material

which fails outgassing, is flammable, etc.). The document includes rationale for acceptance. This RFD would be applicable for all subsequent items manufactured.

RFW - Document which asks customer permission to use a part, material or process where as a result of inspection etc. a non conformance has been identified (e.g. hole drilled in

wrong place, non acceptable adhesive used etc.). This RFW would be applicable to this one item only.


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THE CONFUSION ARISES FROM THE FOLLOWING:

• European companies and ESA are more used to using the term RFW to cover both RFD and RFW. The RFD is called up in ECSS documentation (not consistently) and it is not uncommon to find a statement of work where, for example, ECSS-Q-70A is a requirements document, that a specific change from the use of the term RFD to RFW is included.

• On manned space projects, the term RFA is used in place of the RFD / RFW to give a rationale for approval for safety critical materials and mechanical parts (equivalent to the NASA materials usage agreement, MUA). One added complication is that the format of the RFA is different to that given in either PSS-01-700 or ECSS-Q-70B (draft) and the two should not be confused.


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RFA for Materials Certification

As mentioned earlier on manned space programmes on RFA is used to justify the use of materials / mechanical parts which do not meet the materials requirements related to specify (flammability, offgassing and stresscorrosion). Some examples of completed RFAs are attached.


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PMP FLOW CHART

The approval process for PMP is summarised in the following flow chart.


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Documents

processes ecssq

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ecss specifications

use of materials

pmp ecssq

control of materials

screening of space materials

materials mechanical