Abstract : The purpose of this project was to develop an eddy current nondestructive inspection technique and procedure for the fatigue-critical location on the lower cap lug fillet of the T-37 wing spar, and to develop and conduct an inspection reliability program to quantify the inspection capability. The inspection capability goal was to demonstrate a probability of detection of 90% with a 95% confidence level for 0.050 inch radius fatigue cracks in the critical region of the lug. A hand-operated mechanical probe manipulator was developed to ensure uniform inspection results. A set of test specimens with fatigue cracks was fabricated for the reliability study. All of the goals were met or exceeded in the program. Keywords: Electrical measurement; Nondestructive testing; Jet training aircraft; Wing spar lugs; Fatigue crack detection. (edc)