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AFGROW | DTD Handbook

Handbook for Damage Tolerant Design

  • DTDHandbook
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    • Sections
      • 1. Introduction
      • 2. Fundamentals of Damage Tolerance
      • 3. Damage Size Characterizations
        • 0. Damage Size Characterizations
        • 1. NDI Demonstration of Crack Detection Capability
          • 0. NDI Demonstration of Crack Detection Capability
          • 2. NDI Capability Evaluation for Cracks
          • 3. NDI Capability Evaluation for Corrosion
            • 0. NDI Capability Evaluation for Corrosion
            • 1. Corrosion Metrics
            • 2. Corrosion Specimen Selection and Design
            • 3. Example of Evaluating the Capability of an Eddy Current Inspection to Detect Hidden Corrosion in Lap Joints
        • 2. Equivalent Initial Quality
        • 3. Proof Test Determinations
        • 4. References
      • 4. Residual Strength
      • 5. Analysis Of Damage Growth
      • 6. Examples of Damage Tolerant Analyses
      • 7. Damage Tolerance Testing
      • 8. Force Management and Sustainment Engineering
      • 9. Structural Repairs
      • 10. Guidelines for Damage Tolerance Design and Fracture Control Planning
      • 11. Summary of Stress Intensity Factor Information
    • Examples

Section NDI Capability Evaluation for Corrosion

The impact of corrosion on the sustainment costs of an aging fleet is significant, particularly for transport aircraft.  The presence of corrosion indicates a failure of the corrosion protection system and necessitates some sort of action in the maintenance plan.  Regardless of the corrosion control maintenance strategy, NDI plays an important role in its implementation and the need exists to quantify the corrosion detection capability of the inspection system.

Several types of corrosion are typically found in aging airframes – uniform, pitting, intergranular, exfoliation, crevice (uniform and pitting), and stress corrosion cracking.  Adaptations of the standard NDI methods discussed in Subsection 3.1.1 can be used to detect the various types of corrosion damage and new inspection methods are evolving.  Although there is a need to quantify the corrosion detection capability of an NDI system, at present there is no commonly accepted procedure for doing so.  Approaches to characterizing corrosion detection capability can be found in Alcott [1994], Howard and Mitchell [1995], Roach [1997], Komorowski, et al. [1998], and Hoppe, et al. [2000].  This subsection discusses two of the major problems in quantifying NDI capability for detecting corrosion and describes the method of Hoppe, et al. [2000].