Fluorescent penetrant inspection (FPI) is a type of dye penetrant inspection in which a fluorescent dye is applied to the surface of a non-porous material in order to detect defects that may compromise the integrity or quality of the part in question.

Learn about the Penetrant Inspection method of Nondestructive Testing, including basic steps for NDT with an AMS 2644 Type 1 water washable penetrant. This video explains surface preparation with Spotcheck SKC-S, penetrant application with Zyglo penetrant, dwell time, removing excess penetrant, applying developer and inspecting under UV light for indications.