Lyman,
A Patent has nothing to do with application, permitting, or certification.
Figure this, a paint scheme on the aircraft requires certification. There are also many parts of the aircraft in the common domain, of which there is no patent, that require a cert.
While a thicken edge may work on that specific variant of that specific aircraft, it may not work on a variant of that same aircraft, and certainly not on any other aircraft.
Winglets would be a great example to follow.