2. Royal Lovingfoss John Tomblin Rachael Andrulonis Jeff Gilchrist
Composite Repair Materials Characterization and Qualification Guidelines for Aircraft Design and Certification
Royal Lovingfoss
John Tomblin
Rachael Andrulonis
Jeff Gilchrist

3. Outline
Overview
Program update
NCAMP background

4. Development of Repair Qualification Program
FAA Sponsored Research Program (2016 – 2018)
Overall Goals
Primary goal: To develop a framework for the qualification of new and innovative material platforms for composite repair including guidelines and recommendations for their characterization, testing, design and utilization.
Secondary goal: To transition the test data and guidelines generated in this program into shared databases, such as CMH-17.

5. Technical Approach SURVEY
Develop a framework to advance repair materials into the aerospace industry.
Utilize the experience and framework of the NCAMP composite program as an example of process sensitive material characterization.
Assess the validity with equivalency testing.
SURVEY
Establish Steering Committee and Coordination
Develop Qualification Framework
Validate framework with selected repair material
Establish statistical guidelines
Transition
- Material property data
- Guidelines

6. Survey Results: Industry Needs
Results showed a strong need for the standardization of composite repair.
The need for new materials
Data
Better documentation, training, and information to be included in the repair manuals.
Several recommendations for improvements to existing repair procedures were suggested including:
More closely following current procedures, supplying build data, better NDT procedures and standards, better surface preparation and inspection procedures, more comprehensive process details, repair technology transfer, repairmen minimum training requirements and more extensive use of travelers.

7. Task 1: Steering Committee
Steering committee has been formed with interested individuals
Kick-off meeting was held in January 2017
Monthly teleconferences
Collaboration with CMH-17

8. Task 2: Coordination
Coordinate efforts with other groups and national initiatives working towards characterization, standardization and certification of composite repair materials.
SAE Commercial Aircraft Composite Repair Committee (CACRC)– Repair Materials Task Group – Develop repair material specifications in support of commercial airplane bonded repairs
Repair Materials Task Group – All members invited to join Steering Committee
Joint Technology Exchange Group – Composite Material Repair – DoD group focused on composite repair state of the art and challenges in military applications
Ongoing coordination with Air Force and Navy efforts on repair processing and testing

9. Task 3: Development of Qualification Program
GOAL: Generate the framework for a qualification test program including material and process specifications, test matrices, and documentation requirements.
Objectives:
Select repair material and process to initially develop this framework. The material will be selected with input from the steering committee.
Address quality aspects of the repair material manufacturing process and the framework for a quality assurance program.
Draft material and process specifications for selected material.
Develop a test matrix including required physical and mechanical data tailored to repair materials.
Generate substantial mechanical property test data necessary for development of statistical guidelines using accepted test standards for the selected material.

10. Material Selection Out-of-autoclave prepreg material 5320-1
Fiber form: T650 PW
Baseline processing data approved through CMH-17
Currently included in working draft of handbook
Spec being converted to SAE spec through P-17
It should be noted that the mechanical properties of repair materials, other than metals, depend very strongly on the curing process used. As the repair curing processes are often different than the process used for fabricating the original part (typically lower curing temperature and/or pressure), material suppliers have developed unique materials that are optimized for the repair process.

11. Qualification Documentation
Base Spec (resin system)
NCAMP
Material Specification
Fiber Form
NCAMP
Process Specification
Processing Info (cure)
Pedigree
NCAMP Test Plan
Test Matrix
Statistical Analysis Report
NCAMP Data Analysis
Material Report

12. Resin System: 5320-1 (T650 PW) NCAMP Qualification Database
APPROVED QUALIFICATION DATABASE AND SPECS
Material Specification:
NMS 532
Material Specification:
NMS 532
Material Specification:
NMS 532
Process Specification:
NPS 85321
Process Specification: NEW NPS XXXXX
Process Specification: NEW NPS XXXXX
Cure Cycle “C”:
Vacuum Bag - 250°F cure for 180 minutes
Oven Cure – 350°F for 120 minutes
NEW Cure Cycle:
Optimized cure cycle for repair
Hot bonder
NEW Cure Cycle:
Optimized cure cycle for repair
Hot bonder
NCAMP Qualification Database
NCAMP Equivalency Database (lamina and laminate)
NCAMP Repair Qualification Database (repair specific tests)
Equivalency Test Matrix (new processing spec)

13. New Process Specification
Parent panels for repair test – original cure cycle (NPS 85321)
Process spec includes details on preparation of parent laminate, bagging procedure, hot bonder use in cure
Cure cycle
Modified to use hot bonder
New bagging sequence
Quality Assurance
In process monitoring data
Data like heat blanket temperature to verify uniform temperature

14. Equivalency Test Matrix – Lamina

15. Equivalency Test Matrix - Laminate

16. Parent Laminate Scarfed
Parent laminate panel scarfed, taped to tool and repair alignment lines have been marked with the appropriate direction of the ply designated. 
Once alignment marks are applied, the scarf surface is cleaned and the film adhesive is applied
4 layers of the repair have been applied and the panel was then debulked.  Separator film is applied to protect the prepreg and adhesive from contaminates.
Outcome of the debulk process. 
Top left photo: Parent laminate panel scarfed, taped to tool and repair alignment lines have been marked with the appropriate direction of the ply designated. 
Top left photo and middle top photo very similar....
Top right photo: Once alignment marks are applied, the scarf surface is cleaned and the film adhesive is applied
Bottom Left Photo: 4 layers of the repair have been applied an the panel was then debulked.  Separator film is applied to protect the prepreg and adhesive from contaminates.
Bottom Right Photo: Outcome of the debulk process. 

17. Qualification Repair Specific Tests (Scarf Ratio 50:1)
NDI via C-scan will be performed on all repair panels. Any anomalies should be brought to the attention of NCAMP so a determination of the anomaly severity and determination of use for test.

18. Qualification Repair Specific Tests (Scarf Ratio 30:1)
NDI via C-scan will be performed on all repair panels. Any anomalies should be brought to the attention of NCAMP so a determination of the anomaly severity and determination of use for test.

19. Test Set-Up ASTM D3518 with Biaxial Extensometer ASTM D5766
with back to back gauges
ASTM D5766
with thermocouple
ASTM D7291
with 4 bi-axial gauges
ASTM D6484
ASTM D7137
Impact Tower

20. Task 4: Development of statistical guidelines
GOAL: Understanding of how parameters interact and affect variability as well as final allowables.
Establish qualification statistical requirements. The factors affecting variability will be assessed during this task.
Establish equivalency requirements including specification minimums for acceptance.
Data
Allowables
Equivalency
Specification
limits
The same dataset is used to derive basis values, equivalency limits, and specification limits (i.e. common mean and standard deviation).

21. Task 5: Guidelines and Recommendations
GOAL: To provide guidelines to industry for the collection of statistically meaningful critical data that designers need to utilize repair materials potentially including:
Develop guidance for characterizing existing composite structure for repair design purposes and the application of the repair material within the design
Expand the shared database approach to include repair material test data, material and process specifications and analysis methods.
Development of handbook data and guidelines for CMH-17.

22. NCAMP Background

23. Most are available publicly
NCAMP Background
Industry-shared materials and process specifications
Industry-shared material property data and allowables
May fulfill some coupon level building block requirement
Most are available publicly →
Focuses on basic lamina & laminate properties in support of higher level building blocks
What is NCAMP? (National Center for Advanced Material Performance)
NCAMP is a process for developing design allowables for composite materials. Design allowables that have been qualified and approved through NCAMP will be recognized by the FAA and EASA when the material is fabricated to the NCAMP specifications and has been shown to be equivalent to the baseline material through test. Approved design allowables eventually get published in CMH-17 and then turn into SAE specifications.

24. Timeline of Activity 1995 1998 1998 - 2002 1998 - 2002 2000 2002 2003
AGATE started with General Aviation industry’s desire to share databases and standardize procedures used in material characterization
1995
1998
First AGATE document release – MIL-17 presentation
AGATE databases produced
MIL-17 engagement and revision of qualification and equivalency guidelines (3 revisions) – statistical procedures
2000
FAA Small Airplane Directorate policy memorandum (Policy Statement Number ACE ; Volume 65, Number 114)
2002
FAA Material & Process Specification Guidelines
2003
FAA updated release of qualification and equivalency guidelines DOT/FAA/AR-03/19 (5th revision)
2003
FAA issued AC Material Acceptance Guidance
2005
NASA established NCAMP “Not Just for Small Airplanes”
2006
AFRL and Industry Funded Qualification Programs Began
2009
NCAMP SOP (modeled after FAA process)
2010
FAA acceptance of NCAMP SOP
2014
EASA acceptance of NCAMP SOP

25. AGATE Program & FAA Policy Memo NCAMP Standard Operating Procedures
OEMs QUALIFY THEIR OWN MATERIALS
Same materials are qualified by different OEMs
Heavy workload on the FAA
Material properties not usable by others
Many years delay in data submission to CMH-17 (if ever) with
no M&P spec
PAST (Inefficient)
AGATE Program &
FAA Policy Memo
AGATE SHARED DATABASE APPROACH
Primarily applied to General Aviation Products
FAA accepting the role of CMH-17 and SAE
each material is qualified one time only
reduced workload on the FAA (but still higher than for metals)
FAA-accepted shared material property databases
NCAMP Standard
Operating Procedures
In cooperation with CMH-17, NCAMP seeks to expand use
of shared database
FAA-accepted shared material property databases
Industry self regulate with minimal FAA oversight
supervised and reviewed by OEMs (similar to the “PAST”)
facilitated by CMH-17/SAE/NCAMP
Each material is qualified one time only
No delay in availability of data to CMH-17
2005-FUTURE

26. Equivalency Per DOT/FAA/AR-03/19
Material Qualification Processes
Traditional Process
AGATE Shared Database Process
Company A
Company B
Company C
Company D
Company A
Company C
FAA
ACO A
FAA
ACO B
FAA
ACO C
FAA
ACO D
3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19
3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19
Company B
Company D
Qualification
Plan A
Qualification
Plan B
Qualification
Plan C
Qualification
Plan D
Material X
Properties
Material Y
Properties
1 Batch Process
Equivalency Per DOT/FAA/AR-03/19
Material X
Properties
Material X
Properties
Material Y
Properties
Material Y
Properties
Shared Database
Note: Specification limits and allowables are derived from the same data
MATERIAL PROPERTIES DO NOT IMPROVE THROUGH MULTIPLE QUALS !
In the Traditional Process, design allowable X by company A is not the same as design allowable X by company B
The AGATE approach uses a common qualification plan DOT/FAA/AR-03/19 – it eliminates redundant testing by multiple aircraft companies – an approach co-developed with FAA Small Airplane Directorate so it is acceptable for use in part 23 aircrafts.

27. Material Qualification Processes
NCAMP Shared Database Process
AGATE Shared Database Process
Company A
Company C
Company A
Company C
Initial 3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19 &
DOT/FAA/AR-06/10 &
DOT/FAA/AR-07/3 &
DOT/FAA/AR-02/110
Initial 3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19 &
DOT/FAA/AR-06/10 &
DOT/FAA/AR-07/3 &
DOT/FAA/AR-02/110
3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19
3 or 5 Batch
Qualification per
DOT/FAA/AR-03/19
Company J
Company I
Company B
Company D
Material X
Properties
Material Y
Properties
Material X
Properties
Material Y
Properties
1 Batch Process
Equivalency Per DOT/FAA/AR-03/19 &
DOT/FAA/AR-06/10 &
DOT/FAA/AR-07/3 &
DOT/FAA/AR-02/110
1 Batch Process
Equivalency Per DOT/FAA/AR-03/19
Shared Database
Shared Database
1 Batch Process
Equivalency Per DOT/FAA/AR-03/19 &
DOT/FAA/AR-06/10 &
DOT/FAA/AR-07/3 &
DOT/FAA/AR-02/110
(same time as the Qualification)
1 Batch Process
Equivalency Per DOT/FAA/AR-03/19 &
DOT/FAA/AR-06/10 &
DOT/FAA/AR-07/3 &
DOT/FAA/AR-02/110
(same time as the Qualification)
Company H
Company G
Building on the process developed in the AGATE program, NCAMP’s process is tailored for all types of airplanes and rotorcrafts. In September 20, 2010, FAA HQ issued a policy memo to formally accept the NCAMP shared material property database process for use in all FAA-certified aircrafts/rotorcrafts – see
Company B
Company D
Company E
Company F

28. Equivalency Process Overview
Prepreg from Material Supplier
Composite Panel Fabricated by Equivalency Companies
Specimens Machined by NIAR
If Equivalency is demonstrated, Qualification data may be used in certified aircrafts such as:
Materials and Processes Specifications
Material Property data and Allowables
Specimens Tested by NIAR

29. Updates Specs with Limits
Typical Data Flow
CMH-17 Vol. 1 & Other Requirements
Test Matrix
Test Methods
Data Requirements
Supplier with
new Material
Draft Material Spec
Draft Process Spec
Test Plan
NCAMP
Review Supplier Proposal
for Compliance to CMH-17
and Other Requirements
NCAMP Concurs and Supplies Listing of AER/AIRs
CMH-17/NCAMP Harmonization
Panel Fabrication
Conduct Testing
NCAMP
Regresses Data
Prepares Data Report
Updates Specs with Limits
NCAMP
Publishes
Reports and Specs
Data and Reports
Submitted to CMH-17
Specs Submitted
to SAE P-17
Test and Pedigree Data
Approved Data Report and Specifications
Approved Specs
Approved Data Set
CMH-17 Vol. 2
SAE P-17 Specs

30. Questions?