WFIRST-IC-SPEC-0032-.pdf

Effective Date: June 21, 2019 Expiration Date: June 21, 2024

CHECK https://ipdtdms.gsfc.nasa.gov

TO VERIFY THAT THIS IS THE CORRECT VERSION PRIOR TO USE.

National Aeronautics and Space Administration

Goddard Space Flight Center Greenbelt, Maryland

WFIRST-IC-SPEC-0032, Revision -

Wide Field Infrared Survey Telescope (WFIRST), Code 448

Non-Destructive Examination Specification and

Defect Acceptance Criteria for Non-Metallics

GSFC WFIRST CMO

June 21, 2019

Released https://ipdtdms.gsfc.nasa.gov/

NDE Specification & DAC for Non-Metallics WFIRST-IC-SPEC-0032, Revision -ii

Non-Destructive Examination Specification and Defect-Acceptance Criteria for Non-Metallics

Review/Signature/Approval Page

Prepared by:

Wes Alexander

Approving Signature Authority:

Christopher Tolman

Electronic Approval available on-line at: https://ipdtdms.gsfc.nasa.gov iii

Preface This document is a Wide Field Infrared Survey Telescope (WFIRST) Configuration Management (CM)-controlled document. Changes to this document require prior approval of the applicable Signature Authority or designee. Proposed changes shall be submitted to the WFIRST CM Office (CMO), along with supportive material justifying the proposed change.

In this document, a requirement is identified by “shall,” a good practice by “should,” permission by “may” or “can,” expectation by “will,” and descriptive material by “is.”

Questions or comments concerning this document should be addressed to:

WFIRST Configuration Management Office Mail Stop 448 Goddard Space Flight Center Greenbelt, Maryland 20771 iv

Change History Log

Revision Effective Date Description of Changes (Reference the Signature Authority Approval Date)

Revision - June 21, 2019 This was approved by the WFIRST Signature Authority via WFIRST-SCoRe-0136 on the effective date shown.

v

Table of TBDs/TBRs/TBSs

Item No. Location Summary Individual/ Organization

Actionee

Due Date vi

Table of Contents

1 INTRODUCTION

1.1 Purpose

1.2 Scope

1.3 Related Documentation

1.3.1 Applicable Documents [and Forms]

1.3.2 Reference Documents

2 TEST METHODS AND REQUIREMENTS

2.1 Non-destructive Examination (NDE)

2.2 Contamination

2.3 Methods

2.4 Personnel

2.5 NDE Standards

2.6 Quality Assurance

2.7 Documentation

3 INSPECTION

3.1 Visual Inspection

4 COMPONENT DEFECT ACCEPTANCE CRITERIA

4.1 Flat Laminates

4.2 Laminate clips, caps, channels, tubes and blocks

4.3 Gusset-to-Beam, L-clip-to-beam, Clip to Gusset, and doubler bonds

4.4 Internal metallic fitting to composite tube joint

APPENDIX A ABBREVIATIONS AND ACRONYMS

List of Figures Figure 1. Example Bonding Structures Figure 2. Defect Spacing

List of Tables

Table 1. Composite Structure Configurations and Approved Inspection Methods

1 INTRODUCTION

1.1 Purpose

This specification establishes the requirements for non-destructive examination and defect criteria for non-metallic structures for the Wide Field Infrared Survey Telescope (WFIRST). The contractor is responsible for the all requirements within this specification WFIRST-IC-SPEC- 0032.

1.2 Scope

This specification establishes the requirements for non-destructive examination of non-metallic composite laminates, piece parts, tubes, and bonded assemblies of the Instrument Carrier structure for the WFIRST program.

1.3 Related Documentation

The latest versions of all documents below should be used. WFIRST documents can be obtained from URL: https://ipdtdms.gsfc.nasa.gov.

1.3.1 Applicable Documents [and Forms]

The following documents are referenced within this document and are directly applicable or contain policies or other directive matters that are binding for the contents of this document. In the event of conflict between an Applicable Document and the content of this document, the applicable Signature Authority has the final authority for conflict resolution.

In case of conflicting requirements between the requirements of this specification and those noted on the engineering drawing, the drawing’s requirements shall govern.

Document Number Title WFIRST-IC-SPEC-0046 Instrument Carrier Flight Structure Fabrication Specification ASTM E2580 Standard Practice for Ultrasonic Testing of Flat Panel

Composites and Sandwich Core Materials Used in Aerospace Applications

WFIRST-SYS-PLAN-

WFIRST Contamination Control Plan

NAS-410 NAS Certification and Qualification of Nondestructive Test Personnel

WFIRST-SMA-REQ-0032 Mission Assurance Requirements (MAR)

1.3.2 Reference Documents

The following documents are referenced herein and amplify or clarify the information presented in this document. These documents are not binding on the content of this document.

Document Number Title MIL-HDBK-793 Nondestructive Testing Techniques for Structural Composites ASTM E1316 Standard Terminology for Nondestructive Examinations

2 TEST METHODS AND REQUIREMENTS

2.1 Non-destructive Examination (NDE)

The contractor shall perform 100% non-destructive examination of all composite piece parts at the detail part level after all machining operations are complete and of all bonded joint level. All non-destructive inspections shall be performed by trained and qualified operators using techniques for which controls and standards have been established. Non-destructive inspection of flat laminates, tubes, piece parts, and bonded joints shall be performed with methods capable of finding internal defects, such as delaminations, voids, and porosity.

NDE shall be performed in accordance with the vendor’s procedure using the applicable NDE technique for each individual component, see Table 1. The contractor shall submit an NDE plan for GSFC approval describing the methods, standards, and equipment to be used for inspecting hardware. All non-destructive inspections performed shall comply with the requirements stated in the following subsections and with ASTM E2580 unless otherwise specified in this document.

2.2 Contamination

These methods shall comply with contamination requirements in accordance with WFIRST- SYS-PLAN-0051. Couplants used in each NDE method shall comply with the flight hardware contamination requirements stated in the WFIRST-SYS-PLAN-0051Contamination Control Plan and shall be approved by GSFC prior to use.

2.3 Methods

Approved methods for each component type are defined in Table 1. If an alternative method is used, GSFC must approve this method for the specified component type.

The method of testing must be specified in the manufacturing process traveler, i.e. the traveler shall reference a specific inspection procedure.

2.4 Personnel

NDE equipment operators shall be trained and certified per NAS-410. Evaluation of the inspection results shall be interpreted by personnel certified per NAS-410, level II.

2.5 NDE Standards

The NDE technician shall calibrate the instrument using a standard of the same configuration (i.e. laminate thickness and layup configuration or joint configuration), and demonstrate the ability to consistently detect a pre-determined flaw(s) in this standard. There shall be a standard for each configuration (laminate, joint, etc.).

2.6 Quality Assurance

The results of all inspections which indicate nonconformance shall be submitted to GSFC within 48 hours after the non-conformance is identified. Disposition and corrective action shall be approved by GSFC. All nonconformance processing shall be per WFIRST-SMA-REQ-0032.

2.7 Documentation

The contractor shall retain all NDE inspection records per the WFIRST Mission Assurance Requirements (WFIRST-SMA-REQ-0032). All inspection reports and graphic illustrations shall be retained with the manufacturing traveler and included in the End Item Data Package (EIDP).

3 INSPECTION

3.1 Visual Inspection

Components shall be visually inspected for workmanship requirements listed below:

a. The cured laminate shall be uniform and free of delaminations, dry areas, contamination or blisters. Minor thickness variation that does not violate drawing tolerances due to wrinkles or irregularities is acceptable.

b. No evidence of under cured or over cured adhesive, as indicated soft spots or dark lines.

c. There shall be a continuous flash, or bead, around the entire periphery of bonded joints.

Table 1. Composite Structure Configurations and Approved Inspection Methods

TYPE COMPONENT METHOD TYPE REPORTING

4.1 Flat laminates Ultrasonic

Through transmission or pulse-echo

C-scan and technical sheet via electronic versions of the NDT record

4.2II

Laminate clips, caps, channels, tubes, and

Blocks Ultrasonic

Contact for shaped items, pulse-echo or through transmission for flat blocks

Photograph/sketch showing defect size/location/depth for contact, otherwise

C-scan; technical sheet via electronic versions of the NDT record

4.3III

Gusset-to-Beam, L clip to beam, and doubler bonds Ultrasonic Contact

Photograph/sketch showing defect size/location/depth and technical sheet via electronic versions of the NDT record

4.4V Internal metallic fitting to composite tube Joint Ultrasonic Contact or pulse-echo

Photograph/sketch showing defect size/location/depth for contact, otherwise

C-scan; technical sheet via electronic versions of the NDT record

4 COMPONENT DEFECT ACCEPTANCE CRITERIA

4.1 Flat Laminates

All flat laminates shall meet the following defect acceptance criteria:

a. The maximum permissible defect width/diameter shall be < 0.250 inch. The maximum permissible individual defect area is 0.050 in2.

b. The maximum permissible total flaw area of all defects (AT) in a given panel is AT <

0.60 inch2 within any 6 inch diameter circular area.

c. The minimum permissible flaw spacing (DS) between flaw boundaries is DS > 3 x largest flaw dimension. See Figure 2.

d. Surface scratch depth shall be less than one ply thickness .0028 inches, and shall not sever first ply fibers.

e. Breakout or chipping of an external ply exceeding 0.030 inches from the finished edge of any piece part is not permitted.

Refer to Table 1 for definition of the NDE methods and types that shall be used. Inspection may be performed using a water-coupled system (immersion and squirter systems acceptable) or an air-coupled system. The minimum bake out after water-coupled C-scan shall be 2 hours at 185 +10/-0 °F (85 +6/-0 °C). An electronic C-scan record is required for this inspection.

4.2 Laminate clips, caps, channels, tubes and blocks

All laminate clips, caps, channels, tubes and blocks shall meet the following defect acceptance criteria:

b. The maximum permissible total flaw area of all defects (AT) in a given part of final machined dimensions is AT < 0.60 inch2 within any 6 inch diameter circular area.

c. The minimum permissible flaw spacing (DS) between flaw boundaries is DS > 3 x largest flaw dimension. See Figure 2.

d. Surface scratch depth shall be less than 1 ply thickness, and shall not sever first ply fibers.

Refer to Table 1 for definition of the NDE methods and types that shall be used. If clean deionized water is used as a couplant for either contact, through transmission, or pulse-echo inspection, then laminate parts shall be baked out for a minimum of 2 hours at 185 +10/-0 °F (85 +6/-0 °C). For shaped parts, such as tubes, channels and clips, a photograph or sketch of the part showing any defect locations, sizes, and depths should be included in the inspection report.

An automated method, capable of producing C-scans is preferred for flat components such as thick laminate blocks.

4.3 Gusset-to-Beam, L-clip-to-beam, Clip to Gusset, and doubler bonds All Beam-to-Beam bonded structures shall meet the following defect acceptance criteria:

Figure 1. Example Bonding Structures maximum permissible individual defect area is 0.050 in2.

b. The maximum permissible total flaw area of all defects (AT) in a given joint is 5% of the bonded area.

c. The minimum permissible flaw spacing (DS) between flaw boundaries is DS > 3 x largest flaw dimension. See Figure 2.

d. Defects shall not extend to the edge of the bond.

Refer to Table 1 for definition of the NDE methods and types that shall be used. For contact ultrasonic inspection, using clean deionized water as the couplant, laminate surfaces shall be dried after testing prior to final cleaning. An acceptable drying method is to blow dry using bottled, clean dry nitrogen.

There shall be no evidence of water in the joint or bonded assembly after drying per the above procedure. Detection of water may be by visual, X-ray, or other appropriate method. If there is evidence that any water is present on the part, the drying process shall be repeated and, if necessary, the time extended such that any remaining water is removed. It is permissible to perform the drying process under vacuum.

4.4 Internal metallic fitting to composite tube joint

Bonded joints shall meet the following defect acceptance criteria:

b. The maximum permissible total flaw area of all defects (AT) in a given controlled bond region is 5% of the bonded area.

Clip to Gusset

Clip to Beam

Gusset to Beam

c. The minimum permissible flaw spacing (DS) between flaw boundaries is DS > 3 x largest flaw dimension. See Figure 2.

d. Bond defects shall not extend to the edge of the bond.

Refer to Table 1 for definition of the NDE methods and types that shall be used. For contact ultrasonic inspection, using clean deionized water as the couplant, laminate surfaces shall be dried after testing prior to final cleaning. An acceptable drying method is to blow dry using bottled, clean dry nitrogen.

If the tubes are not part of a larger assembly such that pulse-echo inspection is feasible on a squirter system, then appropriate measures should be taken to seal tube edges and other entry holes in order to prevent water from entering the inner tube. The minimum bake out after water-coupled pulse-echo ultrasonic inspection shall be 4 hours at 185 +10/-0 °F (85 +6/-0 °C). A C-scan record is required for this inspection.

Figure 2. Defect Spacing

Appendix A Abbreviations and Acronyms

Abbreviation/ Acronym

DEFINITION

GSFC Goddard Space Flight Center TBD To Be Determined TBR To Be Revised TBS To Be Scheduled NDE Non-Destructive Inspection WFIRST Wide Field Infrared Survey Telescope