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ECA Subsurface Corrosion Detection


Aircraft around the globe are repeatedly subjected to drastic temperature changes, which cause condensation and humidity to collect on the inside of the aluminum skin. This humid environment between layers leads to hidden corrosion that must be detected and repaired during regular in-service inspections.

As a part of its series of aerospace solutions, Olympus proposes an innovative fastener and subsurface corrosion inspection technique, which propels eddy current technology into previously uncharted territory. This new technology detects, sizes, and evaluates the depth of corrosion between the aluminum layers of commercial and military aircraft, providing efficient and reliable results.


  • Replaces magneto-optical imaging (MOI).
  • 32-coil probe provides large coverage.
  • No need to remove paint; fewer steps means time-savings.
  • Detection similar to conventional eddy current, plus, with ECA:
    • the area of corrosion can be sized; and,
    • the depth of corrosion can be evaluated.
  • With continuous mode, the scan imagery reveals inspection results without interruption.
  • Data recording for professional reports.
  • Optimized to detect typical subsurface corrosion in aluminum sheets with thicknesses of up to 2.5 mm (0.1 in.).

Internal Subsurface Corrosion Area




Area and Depth Color Calibration


In this particular example, corrosion detection gives these values:

PINK= 40% corrosion depth

RED= 30% corrosion depth

YELLOW= 20% corrosion depth

BLUE= 10% corrosion depth

Olympus IMS
Products used for this application

Performs eddy current array testing inspections. The test configuration supports 32 sensor coils (up to 64 with an external multiplexer) working in bridge or transmit-receive mode. The operating frequency ranges from 20 Hz to 6 MHz with the option of using multiple frequencies in the same acquisition.
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