Shearographic Inspection of a Boeing 737

Under a Cooperative Research and Development Agreement between the Volpe National Transportation Systems Center (VNTSC) and Henson Aviation, Inc., operator of USAir Express, a shearographic demonstration inspection of the fuselage of a Boeing 737 aircraft was performed at a USAir repair station at Winston-Salem, NC, during August 1991. The inspection compared the effectiveness of shearography with currently mandated methods in detecting disbonds in the fuselage. Adhesive bonding is utilized in modern aircraft fuselages, frequently in combination with rivets. As aircraft age, bond failure may become a major problem, since it may promote fatigue cracking, moisture intrusion, and subsequent corrosion. Any of these events may cause cabin pressure loss and, sometimes, catastrophic fuselage failure. The shearographic method of detecting disbonds depends on the deformation of the aircraft skin under varying pressurization. When illuminated by coherent light, the phase relationship and intensity of the light reflected from any two points of the skin changes as a result of this deformation. Surface changes down to 0.00025 millimeter can be detected and displayed as a real-time image of the field of view. Comparison of successive images as the pressure changes permits interpretation of the condition of a bond. For this demonstration, 31 disbonds were found by shearography; 25 were confirmed by ultrasound. Of the remainder, six were disbonds on structure where the Sondicator cannot perform reliably; one was a false positive; in addition, there was one Sondicator false positive confirmed by reference to a drawing and by observation. The demonstration indicated potential advantages of shearography over currently used inspection techniques, namely, improved reliability in the detection of disbonds in the fuselage and reduced down-time of the aircraft with concomitant reduced inspection costs.

  • Record URL:
  • Corporate Authors:

    Volpe National Transportation Systems Center

    55 Broadway
    Cambridge, MA  United States  02142

    Federal Aviation Administration

    Technical Center, Atlantic City International Airport
    Atlantic City, NJ  United States  08405
  • Authors:
    • Bobo, Stephen N
  • Publication Date: 1992-7

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Technical Note
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 39p

Subject/Index Terms

Filing Info

  • Accession Number: 01670177
  • Record Type: Publication
  • Report/Paper Numbers: DOT/FAA/CT-TN92/19, DOT-VNTSC-FA1H2-91
  • Files: NTL, TRIS
  • Created Date: May 16 2018 1:42PM