Help!

I'm looking for the reference that IAs use to determine if an airplane
is airworthy despite missing a cowling screw, having wing tip cracks,
or a missing piece of carpeting.

And no, it's not the a/c maintenance manual.

I've searched the FAA site, Google, GPO, etc.

Apparently I'm having a brain cramp and can't think of the reference
or good keywords to use to locate.

Thanks,

Dan Mc