Inspection of Fabricated Fuselage Panels Using Electronic Shearography

This report describes the results of a proof of principle demonstration of using electronic shearography to detect induced damage in fabricated aircraft panels. The demonstration was performed at the FAAs Aircraft Panel Test Facility in Waltham, Massachusetts and all shearography equipment and its operational support was provided by Laser Technology, Inc. LTI under a separate contract from the Volpe National Transportation Systems Center. The test panels that were inspected using the electronic shearography were constructed to closely simulate the fuselage and skin structure of Boeing 727 and 737 aircraft. These panels contained programmed flaws intended to simulate two major types of defects associated with aging aircraft, namely cracks along fastener rows, and disbonded tear strap doublers and lap joints. The proof of principle consisted of a series of inspections that demonstrated shearographys capability to detect cracks and disbonds in the fuselage panel specimens. The sensitivity of shearography to detect short, simulated fatigue cracks that would correspond to a multiple site damage situation was too low to provide sufficient confidence that the method could economically replace existing eddy current surface methods. The sensitivity of the method to detect panel disbonding, however, is sufficient to encourage further development of the technique. Electronic Shearography, NDI, Lap Joint Disbonding, Coherent Light, Strain Fields, Fuselage Panels, Multi Site Damage, B-727B-737.