AC 33.15-1A The output should be electronic C-scan data, which can be acquired, stored, and retrieved electronically and retained according to the engine-manufacturer's FAA- approved records retention schedule.
10.4 Actions Following Indication Detection.
10.4.1 Indication Characterization.
Characterization of unacceptable indications should be conducted on billet/bar, forgings or finished parts, as appropriate, and reported to JETQC in accordance with JETQC practices. This characterization, as appropriate and as a minimum, shall provide the following information (the recommended procedure for 3D inclusion characterization is outlined in appendix B):
• anomaly type,
• 3D anomaly size,
• 3D void/crack size if any,
• microhardness,
• scanning electron microscope (SEM) evaluation: nature of constituents, fractography of void/crack,
• microprobe analysis (currently recommended): chemical composition and nature of anomaly, and
• photomicrographs of anomaly in two perpendicular directions.
10.4.2 Indications Detected in Billet/Bar.
10.4.2.1 HDI or HID.
Any heat which is shown, by billet/bar inspection and indication characterization, to contain an HDI or HID inclusion should be rejected for critical rotating part application.
10.4.2.2 Other.
HAD's and clean voids are considered potentially detrimental; usage of heats shown to contain any of these anomalies should be evaluated on an individual basis.
10.4.3 Indications Detected in Forgings and Finished Parts.
The PAH should take appropriate action upon finding and characterizing unacceptable indications in forgings and finished parts. Action regarding suspect material should be based on historic experience with the process and may include, but not necessarily be limited to, over-inspections of parts from heats, lots, batches, etc., which contain the forging or part with the anomaly.
10.4.4 Associated Heats. Associated heats shall be identified and investigated for similar potential anomalies.
AC 33.15-1A Appendix A Appendix A. Additional References A.1 UNCONTAINED ENGINE FAILURES RELATED TO MELT ANOMALIES
• A.B. Clark, Dillard, B.C. Hendrix, J.K. Tien, and T. Denda, The Role of Melt Related Defects in Fatigue Failures of Ti-6Al-4V, Titanium ’92: Science and Technology, F.H. Froes and I. Caplan, eds, 2867-2874.
• Aviation Investigation Report No. A97F0059, Beijing/Transport Canada Report, Transportation Safety Board of Canada, September 6, 1997.
https://www.tsb.gc.ca/eng/rapportsreports/aviation/1997/a97f0059/a97f0059.html.
• D. Legzdina (Honeywell), G. Lemaitre (Safran), T. Mouzakis (FAA), A.
Woodfield (GE Aviation). Jet Engine Titanium Quality Committee: 2017 Update. International Titanium Association (ITA), October 11, 2017.
https://custom.cvent.com/C2795141339A407CA590D38C49421294/files/35604 07b889847f8841b60e2a9beb626.pdf.
• NTSB - AAR 90/06 (Sioux City DC-10 LOC FIRE), National Transportation Safety Board, Office of Aviation Safety, Aircraft Accident Report AAR-90-06 NTIS No. PB90-910406. United Airlines Flight 232, McDonnel Douglas DC- 10-10, Sioux Gateway Airport, Sioux City, Iowa, July 19, 1989, November 1, 1990, Accident 89J.25.
https://skybrary.aero/sites/default/files/bookshelf/384.pdf.
• Titanium Rotating Components Review Team Report, Federal Aviation Administration, Aircraft Certification Service, Engine and Propeller Directorate, December 14, 1990, vol. 1, 5.
A.2 IMPROVEMENTS LEADING TO REDUCTIONS IN MELT ANOMALY RATES – JETQC STATISTICS POST SIOUX CITY ACCIDENT
• A. Woodfield and C. Shamblen, Titanium Industry Quality Improvements, Ti- 2003: Science and Technology, presented at the 10th World Conference on Titanium, Hamburg, 2003, 2737.
• A. Woodfield and C. Shamblen, Titanium Alloy Melt Process Quality Improvements, Ti-2007: Science and Technology, presented at the 11th World Conference on Titanium, Kyoto, 2007, 151.
• A. Woodfield and G. Lemaitre, Aerospace titanium alloy melt process quality improvements, presented at the 14th World Conference on Titanium, June 11, 2019, La Cité Nantes Events Center, Nantes, France, https://www.matecconferences.org/articles/matecconf/pdf/2020/17/matecconf_ti 2019_04008.pdf.
• A. Woodfield, D. Furrer, J. Moschini, A. Pilchak, and J.M. Ruppert, Continuous, Industry-wide Efforts to Improve the Safety of Titanium Alloy A-1
AC 33.15-1A Appendix A Turbine Engine Rotors, presented at the 15th World Conference on Titanium, June 13, 2023, Edinburgh, Scotland. Chapter 2: Aerospace Applications, pg.
108. https://f1000research.com/documents/13-1126.
A.3 IMPROVEMENTS IN MELTING CONTROLS
• A. Patel and D. Fiore, On the Modeling of Vacuum Arc Remelting Process in Titanium Alloys, 2016 IOP Conference Series: Mater. Sci. Eng. 143 012017.
• G. Ghazal, P. Chapelle, A. Jardy, J. Jourdan, and Y. Millet, Dissolution of High Density Inclusions in Titanium Alloys, ISIJ International, Vol. 52, 2012, No. 1, 1–9.
• J. Van Den Avyle, J. Brooks, and A. Powell, Reducing Defects in Remelt Processes, Journal of Metals, vol. 50, 1998, 22-25.
• L.A. Bertram, P.R. Schunk, S.N. Kempka, F. Spadafora, and R. Minisandram, The Macroscale Simulation of Remelting Process, Journal of Metals, vol. 50, 1998, 18-21.
A.4 UNCONTAINED ENGINE FAILURES RELATED TO DWELL FATIGUE
• Bureau d’Enquêtes et d’Analyses (BEA) BEA2017-0568: Investigation Report:
Accident to the AIRBUS A380-861 equipped with Engine Alliance GP7270 engines registered F-HPJE operated by Air France on September 30, 2017, in cruise over Greenland (Denmark).
https://bea.aero/uploads/tx_elydbrapports/BEA2017-0568.en.pdf.
• K.G Wilkinson, Rolls-Royce RB211, The First Eighteen Months Operating Experience, Tech Air 1973, 2.
• M.A. Cuddihy, A. Stapleton, S. Williams, and F.P.E. Dunne. On cold dwell facet fatigue in titanium alloy aero-engine components, Int. J. Fatigue. Vol. 97, 2017, 177-189.
• M.J. Blackburn and C.C. Law, Influence of Subsurface Defects on Fatigue Properties of Titanium Alloys, Pratt and Whitney Aircraft Group, F33615-75-C- 5138, AFML-TR-77-112, July 1977.
https://apps.dtic.mil/sti/tr/pdf/ADA052883.pdf.
• National Transportation Safety Board, Safety Recommendation A-98-27 through 33 letter, March 6, 1998. https://www.ntsb.gov/safety/safetyrecs/recletters/A98_27_33.pdf.
• National Transportation Safety Board, Safety Recommendation A-00-104 letter, August 9, 2000. https://www.ntsb.gov/safety/safetyrecs/recletters/A00_104.pdf.
A-2
AC 33.15-1A Appendix A A.5 RELATIONSHIP BETWEEN MICROTEXTURE REGIONS AND DWELL
FATIGUE
• A. Pilchak, K. Fox, E. Payton, M. Wiedemann, T. Broderick, P. Delaleau, M.
Glavicic, N. Jenkins, J.M. Ruppert, B. Streich, M. Tsukada, V. Venkatesh, A.
Woodfield, Cold Dwell Fatigue of Titanium Alloys: History, Current State, and Aviation Industry Perspective, Department of Transportation, Federal Aviation Administration, FAA Final Report Number DOT/FAA/TC-23/40, 2024.
https://doi.org/10.21949/rfzv-6285.
• A.L. Pilchak A. Hutson, W.J. Porter, D. Buchanan, and R. John, On the Cyclic and Dwell Fatigue Crack Growth Response of Ti-6Al-4V, 2016, presented at the 13th World Conference on Titanium, V. Venkatesh et al., John Wiley and Sons, 993-998.
• A.L. Pilchak: Fatigue crack growth rates in alpha titanium: faceted versus striation growth, Scripta Materialia, 2013, Vol. 68, 277-280.
• A. Woodfield, M. Gorman, R. Corderman, J. Sutliff and B. Yamrom, Effect of Microstructure on Dwell Fatigue Behavior of Ti-6242, Proceedings of the 8th World Conference on Titanium Ti’95: Science and Technology, 1996, 1116.
• S. Ghosh, M. Mills, S. Rokhlin, V. Sinha, W. Soboyejo, and J.C, Williams, The Evaluation of Cold Dwell Fatigue in Ti-6242, Department of Transportation.
Federal Aviation Administration. FAA Final Report No. AR-06/24, January 2007.
• S. Ghosh, S. Rokhlin, M.C. Brandes, A.L. Pilchak, and J. Williams, The evaluation of Cold Dwell Fatigue in Ti-6242, Department of Transportation.
Federal Aviation Administration. FAA Final Report Number DOT/FAA/TC- 17/57, February 2018. https://rosap.ntl.bts.gov/view/dot/57737.
• V. Venkatesh, R. Noraas, A. Pilchak, S. Tamirisa, K. Calvert, A. Salem, T.
Broderick, M.G. Glavicic, I. Dempster, and V. Saraf, Data driven tools and methods for microtexture classification and dwell fatigue life prediction in dual phase titanium alloys, presented at the 14th World Conference on Titanium, La Cité Nantes Events Center, Nantes, France, 2019.
• A. Pilchak, K. Fox, E. Payton, M. Wiedemann, T. Broderick, P. Delaleau, N.
Jenkins, J.M. Ruppert, B. Streich, M. Tsukada, V. Venkatesh, and A.
Woodfield. Industry-wide Learning and Perspectives on Management of Cold- Dwell Fatigue Capabilities, Proceedings of the 15th World Conf. on Titanium, Ch. 5, pp. 91-96.
A.6 MTR QUANTIFICATION
• A.L. Pilchak, J. Shank, J.C. Tucker, S. Srivatsa, P.N. Fagin, and S.L. Semiatin, A dataset for the development, verification, and validation of microstructuresensitive process models for near-alpha titanium alloys, Integrating Materials A-3
AC 33.15-1A Appendix A and Manufacturing Innovation, vol. 5, 2016: 14, http://www.immijournal.com/content/5/1/14.
• B. Fernandez Silva, M. Jackson, K. Fox, and B.P. Wynne, Tool for automatic macrozone characterization from EBSD data sets of titanium alloys, Journal of Applied Crystallography, 2023, vol. 56, no. 3: 737-749.
• B. Yamrom, Method of Color Coding Orientation Information. United States Patent No. US5592598A, General Electric, January 7, 1997.
• R. Noraas, Potential Industry Standard Approach to Measure and Quantify Microstructures and Microtexture In Titanium, presented at the International Titanium Association (ITA), Mobile, Alabama, USA, September 25, 2019.
• V. Venkatesh, S. Tamirisakalanda, J. Sartkulvanich, K. Calvert, I. Dempster, V.
Saraf, A.A. Salem, S. Rokhlin, T. Broderick, M.G. Glavicic, T. Morton, R.
Shankar, and A. Pilchak, ICME of Microtexture Evolution in Dual Phase Titanium Alloys, presented at the 13th World Conference Meeting on Titanium, August 16-20, 2015: 1909-1912.
A.7 TITANIUM BILLET CONVERSION PROCESSING
• A. Wilson, V. Venkatesh, R. Puther, J. Brooks, S. Fox, The Prediction of Microstructural Development during TIMETAL 6-4 Billet Manufacture, Ti- 2003: Science and Technology, presented at the 10th World Conference on Titanium, Hamburg, Germany, 2003, 321.
• D. Fischer and K. Piper, Premium Quality Titanium Billets Produced by a Highly Sophisticated Rotary Forging Machine, Ti-2003: Science and Technology, presented at the 10th World Conference on Titanium, Hamburg, Germany, 2003, 305.
• M.F. X Gigliotti et al, Titanium Alloy Billet Processing for Low Ultrasonic Noise, Ti-2003: Science and Technology, presented at the 10th World Conference on Titanium, Hamburg, Germany, 2003, 297.
• R. Tricot, Thermomechanical Processing of Titanium Alloys, presented at the 6th World Conference on Titanium, Cannes, France, 1988, 23.
• V. Venkatesh and A.F. Wilson, Application of Microstructure and Damage Models in the Primary Conversion of Ti-6-4, presented at the 11th World Conference on Titanium, M. Ninomi et al., Japan Institute of Metals, Sendai, Japan, 2007, 865-868.
• V. Venkatesh et al., Computational Modeling in the Primary Processing of Titanium: A Review. Journal of the Minerals, Metals, and Materials Society, 2009, vol. 61 no. 5: 45-50.
A-4
AC 33.15-1A Appendix A A.8 RELATIONSHIPS BETWEEN HOT WORKING AND MICROTEXTURE
REGION FORMATION/MINIMIZATION AND STRAIN-INDUCED
POROSITY
• A.L. Pilchak, C.J. Szczepanski, J. Shaffer, A.A. Salem, and S.L. Semiatin, Characterization of Microstructure, Texture, and Microtexture in Near-Alpha Titanium Mill Products, Metallurgical and Materials Transactions A, 2013, vol.
44A, 4881–90.
• A.L. Pilchak, et al., A dataset for the development, verification, and validation of microstructure-sensitive process models for near-alpha titanium alloys, Integrating Materials and Manufacturing Innovation, 2016, https://doi.org/10.1186/s40192-016-0056-1.
• P. Ari-Gur, and S.L. Semiatin, Evolution of microstructure, macrotexture and microtexture during hot rolling of Ti-6Al-4V. Materials Science and Engineering A, 1998, vol. 257(1), 118-127.
• Bieler, T. R., and Semiatin, S. L., The origins of heterogeneous deformation during primary hot working of Ti-6Al-4V. International Journal of Plasticity, 2002, vol. 18(9): 1165-1189.
• B. Silva Fernandez, The Effect of Thermomechanical Processing on Texture, Macrozones and Cold Dwell Fatigue Performance in a Ti834 Compressor Disc Alloy. PhD thesis, University of Sheffield, 2021.
• J. Warwick, N.G. Jones, I. Bantounas, M. Preuss, and D. Dye, In situ observation of texture and microstructure evolution during rolling and globularization of Ti-6Al-4V. Acta Materialia, 2013, vol. 61(5): 1603-1615.
• N. Gey, P. Bocher, E. Uta, L. Germain, and M. Humbert, Texture and microtexture variations in a near-alpha titanium forged disk of bimodal microstructure. Acta Materialia, 2012, vol. 60(6-7): 2647-2655.
• R. Ma, Investigating the evolution of microtextured region in Ti-6242 using FE- FFT multiscale modeling method. University of Tennessee, 2018.
https://trace.tennessee.edu/utk_graddiss.
• R. Ma, A.L. Pilchak, S.L. Semiatin, and T.J. Truster, Modeling the evolution of microtextured regions during α/β processing using the crystal plasticity finite element method. International Journal of Plasticity, 2018, vol. 107: 189–206.
https://doi.org/10.1016/j.ijplas.2018.04.004.
• S.L. Semiatin, An Overview of the Thermomechanical Processing of Alpha/Beta Titanium Alloys: Current Status and Future Research Opportunities, Metall.
Mater. Trans. A, 2020, vol. 51A: 2593-2625.
A.9 ALLOY CHEMISTRY EFFECTS ON MTRS AND COLD DWELL FATIGUE
• D.F. Neal, Creep Fatigue Interactions in Titanium Alloys, presented at the 6th World Titanium Conference Proceedings, 1988 - Cannes, France, 175-180.
A-5
AC 33.15-1A Appendix A
• J. Qiu, Y. Ma, and J. Lei et al, A comparative study on dwell fatigue of Ti-6Al- 2Sn-4Zr-xMo (x = 2 to 6) alloys on a microstructure-normalized basis.
Metallurgical and Material Transactions, 2014, vol. 45: 6075–6087.
• Z. Wu, H. Kou, N. Chen, Z. Xi, J. Fan, B. Tang, and J. Li, Recent Developments In Cold Dwell Fatigue Of Titanium Alloys For Aero-Engine Applications: A Review. Journal of Materials Research and Technology, 2022, vol. 20, 469–484.
https://doi.org/10.1016/j.jmrt.2022.07.094.
A.10 TEMPERATURE EFFECTS ON COLD DWELL FATIGUE
• D.F. Neal. Creep Fatigue Interactions in Titanium Alloys. presented in the proceedings of the 6th World Titanium Conference, 1988 – Cannes, France, 175-180.
• S. H. Spence, W.J. Evans, and M. Cope, Dwell fatigue on Ti 6246 at near ambient temperatures. Advances in Fracture Research, 1997, ICF 9, vol. 3:
1571–1578.
• Winstone, M. R. and Weaver, M. J. The strain controlled fatigue behaviour of a near-alpha titanium alloy. Titanium: Science and Technology, presented at the 5th International Titanium Conference, 1985, Munich, Free State of Germany, 2275–2280.
• Z. Zhang, M.A. Cuddihy, and F.P.E. Dunne, On Rate-Dependent Polycrystal Deformation: The Temperature Sensitivity Of Cold Dwell Fatigue, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2015, vol. 471: 2181. https://doi.org/10.1098/rspa.2015.0214.
• Z. Zebang, D.S. Balint, and F.P.E. Dunne, Mechanistic Basis Of Temperature- Dependent Dwell Fatigue In Titanium Alloys. Journal of the Mechanics and Physics of Solids, 2017, vol. 107: 185–203.
https://doi.org/10.1016/j.jmps.2017.07.010.
A.11 RELATIONSHIP BETWEEN MTRS AND ULTRASONIC RESPONSE
• A.L. Pilchak, J. Li, and S. Rokhlin, Quantitative Comparison of Microtexture in Near-Alpha Titanium Measured by Ultrasonic Scattering and Electron Backscatter Diffraction, Metallurgical and Materials Transactions A, 2014, vol.
45(10): 4679-4697.
• A. Bhattacharjee, A.L. Pilchak, O.I. Lobkis, J.W. Foltz, S.I. Rockhlin and J.C.
Williams, Correlating Ultrasonic Attenuation With Microtexture In A Near Alpha Titanium Alloy, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 2011, vol. 42(8): 2358-2372.
• B. Ginty, P. Hallam. C. Hammond, G. Jackson, and C. Robb, The Influence of Microstructure on Ultrasonic Response in a Titanium Alloy Forging. In H.
Kimura and O. Izumi (Eds.), Ti’80 Science and Technology: presented at the A-6
AC 33.15-1A Appendix A 4th International Conference on Titanium, Metallurgical Society of AIME, 1980, vol. 3: 2095–2103.
https://cdn.ymaws.com/titanium.org/resource/resmgr/ZZ-WTCP1980- VOL3/1980_Vol_3.-4-The_Influence_.pdf.
• F.J. Margetan, R.B. Thompson, and I. Yalda-Mooshabad, Backscattered Microstructural Noise In Ultrasonic Toneburst Inspections. Journal of Nondestructive Evaluation, 1994, vol. 13(3): 111–136.
https://doi.org/10.1007/BF00728250.
• Fundamental Studies: Inspection Properties for Engine Titanium Alloys, Department of Transportation, Federal Aviation Administration, FAA Final Report Number DOT/FAA/AR-02/114: 2002.
https://apps.dtic.mil/sti/pdfs/ADA411492.pdf.
• Inspection Development for Titanium Billet – Engine Titanium Consortium Phase II, Department of Transportation, Federal Aviation Administration, Final FAA Report No. DOT/FAA/AR-05/30, 2005.
https://www.govinfo.gov/content/pkg/GOVPUB-TD4-PURL- LPS64487/pdf/GOVPUB-TD4-PURL-LPS64487.pdf.
• J.L. Blackshire, J.K. Na, and K. Daugherty, Coherent Ultrasonic Backscatter Within a Textured Titanium Alloy, presented at the AIP Conference, 2019, vol.
2102(1): 020021. https://doi.org/10.1063/1.5099725.
• M.F.X Gigliotti, B.P. Bewlay, J.B. Deaton, R.S. Gilmore, and G.A. Salishchev, Microstructure-Ultrasonic Inspectability Relationships In Ti6242, signal-tonoise in fine-grain-processed Ti6242. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 2002, vol. 31A(9): 2119-2125.
• M. Humbert, A. Moreau, E. Uta, N. Gey, P. Bocher, and C. Bescond, Analysis Of Backscattered Ultrasound Amplitude Of Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-
0.3Si In Terms Of Their Microstructures And Local Textures. Acta Materialia, 2009, vol. 57(3): 708-714.
• M. Mills, S. Ghosh, S. Rokhlin, M.C. Brandes, A.L. Pilchak, and J. Williams, The evaluation of Cold Dwell Fatigue in Ti-6242, Department of Transportation, Federal Aviation Administration, FAA Final Report Number DOT/FAA/TC-17/57, 2018.
• S.I. Rokhlin, J. Li, and G. Sha, Far-field scattering model for wave propagation in random media. The Journal of the Acoustical Society of America, 2015, vol.
137(5): 2655–2669. https://doi.org/10.1121/1.4919333.
• S.I. Rokhlin, G. Sha, J. Li, and A.L. Pilchak, Inversion methodology for ultrasonic characterization of polycrystals with clusters of preferentially oriented grains. Ultrasonics, 2021, vol. 115: 106433.
https://doi.org/10.1016/j.ultras.2021.106433.
• Y.K. Han, and R.B. Thompson, Ultrasonic Backscattering In Duplex Microstructures: Theory And Application To Titanium Alloys. Metallurgical and A-7
AC 33.15-1A Appendix A Materials Transactions A, 1997, vol. 28(1): 91–104.
https://doi.org/10.1007/s11661-997-0085-7.
A-8
AC 33.15-1A Appendix B Appendix B. Minimum Recommended Procedure for 3D Inclusion Characterization STEP 1: Characterize the ultrasonic indication in the product:
• Angulation,
• Two different frequencies, and
• Exact location (marking).
STEP 2: Cut a sample (approximately 40 mm x 40 mm) out of the product containing the indication (mark each face to maintain orientation).
STEP 3: Conduct an NDT Inspection.
STEP 4: Relocate indication ultrasonically and remark (to maintain orientation).
STEP 5: Cut a cube whose side is approximately 25mm (1 inch). If necessary, relocate the indication ultrasonically.
STEP 6: Consider performing 3D Computer Aided Tomography (CAT) scanning or other NDT technique to assist in determination of the 3D shape and size of the anomaly.
STEP 7: Metallurgical characterization:
1. Approach:
• Approach the anomaly by the face of the cube perpendicular to face exhibiting the maximum ultrasonic response, and
• Precut at 2 mm from identified position.
2. Macrographic examination:
• Any segregation, and
• Orientation of grain structure.
3. Micrographic examination:
• Polish in steps from 50 to 500 microns,
• Determine anomaly type, 3D anomaly size, 3D void/crack size, microhardness, and
• Take photomicrographs of the anomaly at each polishing step to establish its maximum dimensions in two perpendicular directions.
4. Recommend performing 3D CAT scanning or other NDT technique to assist in determination of the 3D shape and size of the anomaly.
5. Microprobe analysis (currently recommended) (in case of inclusion): Chemical composition of the anomaly.
B-1
6. Scanning Electron Microscope (SEM) examination (if necessary):
• Nature of constituents, and
• Fractography of void/crack.
This is the minimum procedure recommended for any characterization of inclusion (HID, HDI) on billet/bar, forging, or finished part. Additional Requirements may be established by the PAH.
AC 33.15-1A Appendix B B-2
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