Journal of Failure Analysis and Prevention

, Volume 4, Issue 5, pp 39–49 | Cite as

Failure of a screw in a helicopter fuel-control unit: Was it the cause of a fatal crash?

  • S. P. Lynch
  • D. P. Edwards
  • A. Crosky
Peer Reviewed Articles


Investigations into a fatal helicopter crash centered around the failure of a cadmium-plated, non-conforming, steel screw in a fuel-control unit. The present study, which includes a critical evaluation of previous investigations, was undertaken with the aim of getting more definitive answers as to whether the screw failed in flight due to hydrogen-embrittlement or stress-corrosion cracking, or whether the screw failed due to liquid-metal embrittlement during a post-crash fire. Previous investigations had not resulted in any consensus regarding the mode of failure or whether the failure was responsible for the crash.


cadmium-plated steel screw energy-dispersive spectroscopy failure analysis hydrogen-embrittlement liquid-metal embrittlement stress-corrosion cracking 


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  1. 1.
    J.H. Bickford: “An Introduction to the Design and Behavior of Bolted Joints,” 2nd ed., Marcel Dekker, New York, 1990.Google Scholar
  2. 2.
    D.W. Cameron: “Failures in Large Gas Turbines due to Liquid-Metal Embrittlement,” Mater. Charact., 1994, 33, pp. 37–43.CrossRefGoogle Scholar
  3. 3.
    H.E. Ebert: “Liquid Metal Embrittlement of Flange Connector Studs in Contact with Cadmium,” Handbook of Case Histories in Failure Analysis, vol. 1, ASM International, Materials Park, OH, 1992, pp. 335–37.Google Scholar
  4. 4.
    S.P. Lynch: “Failures of Structures and Components by Environmentally Assisted Cracking,” Eng. Fail. Anal., 1994, 1, pp. 77–90.CrossRefGoogle Scholar
  5. 5.
    A.J. de Marcay and W.G. Hoover: “Cadmium-Coated Fasteners Cause LME,” Mater. Perform., 1991, p. 67.Google Scholar
  6. 6.
    L. Raymond: “The Susceptibility of Fasteners to Hydrogen Embrittlement and Stress Corrosion Cracking,” Handbook of Bolts and Bolted Joints, J.H. Bickford and S. Nasser, ed., Marcel Dekker, New York, 1998.Google Scholar
  7. 7.
    M.H. Kamdar: “Liquid Metal Embrittlement,” Failure Analysis and Prevention, vol. 11, ASM Handbook, American Society for Metals, Metals Park, OH, 1986, pp. 225–38.Google Scholar
  8. 8.
    S.P. Lynch: “Metal Induced Embrittlement of Materials,” Mater. Charact., 1992, 28, pp. 279–89.CrossRefGoogle Scholar
  9. 9.
    C.R. Brooks and A. Choudhury: Failure Analysis of Engineering Materials, McGraw-Hill, New York, 2002.Google Scholar
  10. 10.
    D.N. Fager and W.F. Spurr: “Solid Cadmium Embrittlement: Steel Alloys,” Corrosion, 1971, 27, pp. 72–76.Google Scholar
  11. 11.
    P. Gordon and H.H. An: “The Mechanism of Crack Initiation and Crack Propagation in Metal-Induced Embrittlement of Metals,” Metall. Trans. A, 1982, 13, pp. 457–72.CrossRefGoogle Scholar
  12. 12.
    M.O. Speidel: “Branching of Stress Corrosion Cracks in Aluminum Alloys,” The Theory of Stress Corrosion Cracking in Alloys, J.C. Scully, ed., NATO, Brussels, 1971, pp. 345–53.Google Scholar
  13. 13.
    A.R. Elsea and E.E. Fletcher: “Hydrogen-Induced Delayed Brittle Failures of High-Strength Steels,” DMIC Report 196, Defense Metals Information Center, Battelle Memorial Institute, Columbus, OH, Jan. 20, 1964.Google Scholar
  14. 14.
    A.R. Troiano: “The Role of Hydrogen and Other Interstitials in the Mechanical Behavior of Metals,” Trans. ASM, 1960, 52, pp. 54–80.Google Scholar
  15. 15.
    T.J. Hughel: “Delayed Failure of Class 12.8 Bolts in Automotive Rear Suspensions,” SAE Technical Paper Series, 820122, Society of Automotive Engineers, Warrendale, PA, 1982, pp. 439–44.Google Scholar
  16. 16.
    Y. Asayama: “Metal-Induced Embrittlement of Steels,” Liquid and Solid Metal Induced Embrittlement, M.H. Kamdar, ed., American Institute of Mining, Metallurgical and Petroleum Engineers, Littleton, CO, 1984, pp. 317–31.Google Scholar

Copyright information

© ASM International 2004

Authors and Affiliations

  • S. P. Lynch
    • 1
  • D. P. Edwards
    • 2
  • A. Crosky
    • 3
  1. 1.School of Physics and Materials EngineeringMonash UniversityMelbourneAustralia
  2. 2.Defence Science and Technology OrganisationMelbourneAustralia
  3. 3.School of Materials Science and EngineeringUniversity of New South WalesSydneyAustralia

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