Process Specification Guidelines

1. Process Specification Guidelines FAA/NASA Workshop 6 August 2002

2. Topics to be Covered • Objective • Role within the Certification Process • Test Panel Fabrication • Process Specification Styles • Recommended Process Specification Format

3. Topics to be Covered • Producibility Demonstration Guidelines • Discriminator Panel • First Article Inspection • Destructive Inspection • Fabricator Qualification

4. Objective To establish a definitive set of recommendations to guide the development of new and revised composite prepreg process specifications for use in fabricating test panel laminates.

5. Role within the Certification Process

6. Role within the Certification Process • Material and Process Specifications are inter-woven through out the certification validation process. • Process specifications define and control the processes used for the conversion of materials into structural components. • Composite laminate properties are directly determined by the specific processes used for their fabrication. • It is critical that the test specimens fabricated through the various levels of the Building Block Approach utilize the same process, and that this process is representative of the process that will be used in the fabrication of production aircraft/rotorcraft.

7. Test Panel Fabrication • The fabrication of consistent test panels during the certification process is critical. • Processes used to fabricate test panels must be stable and consistent, and equivalent to the full-scale production processes. • Process specifications ensure consistent test panel fabrication.

8. Process Specification Styles • Detailed process requirements and procedures, • End item requirements only, or • A mixture of process requirements and procedures, and end-item requirements.

9. Recommended Process Specification Format 1. Scope 2. Applicable Documents 3. Requirements 3.1 Personnel 3.2 Required Materials 3.3 Required Equipment 3.4 Facilities 3.5 Tooling 3.6 Required Procedures 4. Quality Assurance 4.1 Responsibility for Inspection 4.2 Inspection 4.3 Documentation 4.4 Test Methods 5. Notes

10. 1.0 Scope • The scope section defines the purpose or application of the specification. • Laminates processed in accordance with this specification are used in the qualification of new materials or establishment of mechanical property equivalency.

11. 2.0 Applicable Documents • This section of the process specification lists all the supporting documents, reports, specifications, or standards referenced within the process specification.

12. 3.0 Requirements The requirements section defines the required process procedures and end item requirements. 3.1 Personnel 3.2 Required Materials 3.3 Required Equipment 3.4 Facilities 3.5 Tooling 3.6 Required Procedures

13. Important Procedures to Define • Ply Orientation (accuracy, reference line) • Lay up Conditions (temp. & humidity) • Bagging Sequence (detail stack up, breathing path) • Cure Cycle (rate, time, vacuum, pressure) • Ply Collation (debulking) • Machining / Drilling Parameters • Inspection Criteria (thickness, Vf, porosity)

14. 4.0 Quality Assurance • The Quality Assurance section defines all the examinations, inspections, and tests to be performed in order to verify that the processes, as well as the equipment, specified in the Requirements section are followed. • Each required inspection or examination should be tied directly to the Requirements section.

15. 5.0 Notes • The Notes section contains definitions and relevant information.

16. Producibility Demonstration Guidelines Discriminator Panel • Test panels do not discern material attributes that can impact ability to fabricate large scale laminates. • Scale up effects must be addressed to fully evaluate a composite prepreg material. • The need exists for a panel design that will “discriminate” these material changes. • The objective of the “Discriminator Panel” is to distinguish one material from another similar (or like) material by exposing the differences related to fabrication processes.

17. Producibility Demonstration Guidelines First Article Inspection • The objective of the First Article Inspection (FAI) is to verify that everything has come together (specifications, tooling, process instructions, process parameters, and design details) to produce an acceptable part. • The FAI is performed to verify form, fit, and function. • The FAI should be performed on all components.

18. Producibility Demonstration Guidelines Destructive Inspection • Verify the performance properties establish during coupon and element level testing are the same in the component. • Quantify internal defects or indications detected by nondestructive inspection, i.e. validate nondestructive inspection methods. • Validate laminate physical properties (resin content and thickness). • Verify fiber path continuity within joints and complicated geometries (typically features that can not be verified through a Discriminator Panel or by nondestructive inspection).

19. Fabricator Qualification • Test panel, element, and component fabrication is performed by a fabricator different from the production components. • This difference in fabricators could result in material properties that are not equivalent. • Fabricators need to be qualified to validate that their processes yield properties that are from the same statistical population as the qualification and allowables data. • The fabricator validates their processes through fabrication and testing of test coupons, discriminator panels, FAI, and destruct articles.

20. Workshop Expectations • Comments, criticisms, and contributions from you. • Your contributions will be reviewed, discussed, and incorporated into the final document. • Thanks in advance for your help.