Affiliations: [a] Department of Physics, Royal Military College of
Canada, Kingston, ON, Canada | Université Laval, Canada | Tohoku University, Japan
Correspondence:
[*]
Corresponding author: Ross Underhil, Department of Physics,
Royal Military College of Canada, Kingston, ON K7K 7B4, Canada. E-mail:
ross.underhill@rmc.ca
Abstract: Stress corrosion cracks may develop between fasteners in the
aluminum inner wing spars of F/A-18 (CF188 Hornet) aircraft. These fasteners
secure carbon-fibre/epoxy composite wing skin, of varying thickness (8 to 21
mm), to the spar. Inspection of the spar through the wing skin is required in
order to avoid wing disassembly. A pulsed eddy current system that uses
principal component analysis and discriminant analysis to identify cracks has
been field tested at the USN North Island facility. The results show that the
system can accurately identify cracks in real time throughout the wing. The
method is far faster than X-ray radiography and, because it is very portable,
can be readily deployed to second or first line facilities. Issues that need to
be addressed to improve the performance of the system are identified and
potential solutions are examined.
Keywords: Pulsed eddy current, aluminium, principal components analysis, discriminant analysis
