Practical Failure Analysis

, Volume 1, Issue 5, pp 43–51 | Cite as

Aftermarket parts: Are they all they’re ‘cracked’ up to be?

  • V. K. Champagne
Peer Reviewed Articles


This paper summarizes the results of a failure analysis investigation of a fractured main support bridge from an army helicopter. The part, manufactured by “Contractor IT,” failed component fatigue testing while those of the original equipment manufacturer (OEM) passed. Even though the same technical data package was used by both manufacturers and there were no material discrepancies found, a great disparity existed in the fatigue test data. This has been a recurring problem within the Army and the intent of this paper is to provide some insight as to the technical reasons why this can occur. Emphasis will be placed on the effects of manufacturing processes on fatigue. Other failure analyses will be discussed in relationship to this topic.

Objective: To perform a metallurgical examination comparing components fabricated by “Contractor IT” to those of the OEM, with the intent of determining the disparity in fatigue life.


failure analysis fatigue 7075 Al shot peening 


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  1. 1.
    Aluminum: Properties and Physical Metallurgy, J. E. Hatch, ed., American Society for Metals, Metals Park, Ohio, 1984, p. 364.Google Scholar
  2. 2.
    Personal conversation with Win Welsch, 15 Sept. 1999, during meeting at the Army Research Lab, Maryland.Google Scholar
  3. 3.
    Residual Stress Measurement by X-Ray Diffraction — SAE J784a, Society of Automotive Engineers, Waarendale, PA, 1971.Google Scholar

Copyright information

© ASM International - The Materials Information Society 2001

Authors and Affiliations

  • V. K. Champagne
    • 1
  1. 1.U.S. Army Research Laboratory (ARL), Weapons and Materials Research Directorate (AMSRL-WM-MD)Aberdeen Proving GroundAberdeen

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