Lyman: I think I see what you're trying to get at with your questioning.
When an organisation applies for, and is granted, an STC by the FAA/EASA/etc, they effectively 'own' that modification. If anyone else would like to perform the same installation under the cover of that STC, they would need to be given the relevant design/installation/cert data by the initial organisation.
So, is there an inherent value to undertaking an STC? Yes, there is, if it's something that other aircraft owners want.
A good working example would be the recent regulatory changes which require 8.33 kHz spaced communication radios. Let's say I designed a modification for the 737 Classic to replace the existing radios with compliant radios under an STC. I could reasonably expect to be able to 'sell' the use of this STC to other 737 Classic owners, under which they could upgrade their radios.
An STC isn't exclusively a mechanism for protecting intellectual property, but it does permit you to own a particular modification which you can then sell to others.
Last edited by Another St Ivian; 30th May 2012 at 11:35.