Details:

Creators:
Bobo, Stephen N.
Corporate Creators:
John A. Volpe National Transportation Systems Center (U.S.)
Corporate Contributors:
Federal Aviation Administration Technical Center (U.S.)
Subject/TRT Terms:
[+]
Aging (Materials) Aircraft Inspection Nondestructive Tests
Publication/ Report Number:
DOT-VNTSC-FA1H2-91 ; DOT/FAA/CT-TN92/19
DOT-VNTSC-FA1H2-91 ; DOT/FAA/CT-TN92/19 Less -
Resource Type:
Tech Report
Geographical Coverage:
North Carolina
Edition:
Technical note; Jul 1992
Corporate Publisher:
Federal Aviation Administration Technical Center (U.S.)
NTL Classification:
NTL-AVIATION-AVIATION;NTL-AVIATION-Aviation Safety/Airworthiness;
Abstract:
Under a Cooperative Research and Development Agreement between 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 millimeters 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.
Format:
PDF
Collection(s):
Volpe
Main Document Checksum:
[+]
urn:sha256:9897ee4266a44ca5ac051b2a29cc370ae616b13a68b440abdc667a2fb3ffc8be
Download URL:
https://rosap.ntl.bts.gov/view/dot/35787/dot_35787_DS1.pdf
File Type:

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