Topographic Radioscopic Metrology for Corrosion Mapping

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Topographic Radioscopic Metrology for Corrosion Mapping

J. C. Brausch

Corrosion of aging aircraft is a pivotal concern in today's Air Force as large transport and tanker aircraft are utilized well beyond their intended design life. The C/KC-135 aircraft, built in the late 1950's and early 1960's is currently projected for service through the year 2040. Inspection for lap-joint corrosion on the C/KC-135 during depot maintenance has historically been conducted in a quasi-destructive manner. The Aging Aircraft Disassembly and Hidden Corrosion Detection Program, conducted at the Oklahoma City Air Logistics Center (OC-ALC), is attempting to identify off the-shelf nondestructive inspection (NDI) equipment and technologies that can accurately detect and quantify corrosion in fuselage lap-joint structures of the C/KC-135 and E-3 aircraft. OC-ALC requested that the materials Directorate of Wright Laboratory develop a laboratory meterological tool by which the corrosion on disassembled aircraft fuselage skins can be accurately measured and mapped. This tool would be used to produce the solution set by which the vendor 'round-robin' inspections would be graded. The resulting technique, Topographic Radioscopic Metrology (TRM), exploits the calibrated gray scale of a digitized radioscopic image through image processing. The resulting 'corrosion maps' supply a topographical quantification of material loss due to corrosion.