I am also a C cert licensed engineer with over 20 years experience.
I'm intrigued as to what that means? Do you clear check inputs?
Are you also B1/B2? If you got the C cert off the back of a degree then you only got it in the last 4 1/2 years if you don't hold any other lic cats with approvals.
I got my C license on all my types because I was clearing SMICRS on Base checks already for a few years when I chopped in my BCAR A&C for a full B1 when I passed the restriction modules and had the necessary experience requirements a few years back