These have in recent postings and in recent days been bantered around on "The Forums".
All of the above have been used in some discussions as if they can be traded around and used as need to be "installed as they where approved" on different aircraft. In fact they are all a ONE TIME document specific to one (1) aircraft unless approved "For use on multiple aircraft".
STC's are for multiple type of applications.
PMA'd and TSO'd items are a manufacturing, testing and approval process. Another thread (Archived) has addressed those issues.
There is also the "Field Aproval" process under 43.13 - 210 which in some circles is considered a "one time STC" (archived)
Spell check is recommended
