TDA RESEARCH, INC. — Department of Defense SBIR Phase I: N221-013

Description

Liquid dye fluorescent penetrant inspection (FPI) is a workhorse tool for evaluating stress-corrosion-cracking (SCC) in aerospace aluminum structures. In this method, a fluorescent dye solution penetrates any cracks on the surface of a metal part.  After wiping away excess solution and applying a developer to a part, any cracks will be revealed by the fluorescent dye when the part is irradiated with an appropriate light source.  Before an area can be inspected, several layers of coatings must be removed in ways that can smear metal or debris into the small cracks and hide them from FPI. Therefore, surface preparation, in the form of a sequence of etching, desmutting and neutralization chemicals is applied to clean the surface for FPI and ensure all the cracks are ready to receive the dye. Current surface preparation products are low-viscosity, and can run out of the inspection area and damage or corrode other areas of the aircraft. In this SBIR project, TDA Research Inc. will develop a higher viscosity set of etch/desmut/neutralization chemistries which provide the desired metal etch rate and surface crack clean out, but do not run out of the FPI inspection area.