Color changing adhesive bond primer

1. A thickness-detecting bond primer, comprising:

a solvent configured for application to a metallic surface; and

a dye dispersed within the solvent, the dye having a concentration within a range of about 0.001 weight percent to about 5.0 weight percent of the thickness-detecting bond primer,

wherein the concentration of the dye is about 0.004 weight percent to about 0.04 weight percent of the thickness-detecting bond primer,

wherein the solvent comprises a diacetone alcohol within about 14.94 to about 39.84 weight percent of the thickness-detecting bond primer and a methyl ethyl ketone within about 14.94 to about 39.84 weight percent of the thickness-detecting bond primer and

wherein the dye is configured for detection of a target layer-thickness of about 0.0001 to about 0.0003 inches and to distinguish a thickness greater than or less than the target layer-thickness via a color change of the dye.

2. The thickness-detecting bond primer of claim 1 , wherein the dye comprises a heterocyclic organic component.

3. The thickness-detecting bond primer of claim 2 , wherein the heterocyclic organic component is about 0.003 weight percent to about 0.05 weight percent of the thickness-detecting bond primer.

4. The thickness-detecting bond primer of claim 3 , wherein the heterocyclic organic component is about 0.004 weight percent to about 0.04 weight percent of the thickness-detecting bond primer.

5. A method of adhering a first metallic component to a second metallic component, comprising:

performing an etching process to a first surface of the first metallic component and to a second surface of the second metallic component;

applying a thickness-detecting bond primer to the first surface and to the second surface, the thickness-detecting bond primer comprising a solvent and a dye dispersed within the solvent, the dye having a concentration within a range of about 0.001 weight percent to about 5.0 weight percent of the thickness-detecting bond primer,

wherein the concentration of the dye is about 0.004 weight percent to about 0.04 weight percent of the thickness-detecting bond primer,

wherein the solvent comprises a diacetone alcohol within about 14.94 to about 39.84 weight percent of the thickness-detecting bond primer and a methyl ethyl ketone within about 14.94 to about 39.84 weight percent of the thickness-detecting bond primer and

wherein the dye is configured for detection of a target layer-thickness of about 0.0001 to about 0.0003 inches and to distinguish a thickness greater than or less than the target layer-thickness via a color change of the dye;

curing the thickness-detecting bond primer;

applying an adhesive to the thickness-detecting bond primer following curing the thickness-detecting bond primer; and

bringing the first surface into contact with the second surface and allowing the adhesive to cure.

6. The method of claim 5 , wherein the dye comprises a heterocyclic organic component.

7. The method of claim 5 , further comprising detecting a target layer-thickness of about 0.0001 to about 0.0003 inches of the thickness-detecting bond primer following curing the thickness-detecting bond primer via a color change of the dye.

8. The method of claim 7 , wherein the first metallic component is a fan blade substructure and the second metallic component is a leading edge sheath or a suction side cover.

9. The method of claim 8 , wherein each of the fan blade substructure, the leading edge sheath and the suction side cover comprises a titanium alloy or an aluminum alloy.