Since you’ve brought different topics in a single post, I’ll address each separately and see where it goes. Otherwise, we can easily slide down a rabbit hole trying to address them all together.
Ok, let's say you have an idea. You spend the considerable sums to obtain the required technical data and testing and prototypes to satisfy the FAA's technical requirements,
“Considerable sums” is very subjective and highly dependent on the part complexity, part use, in-house capabilities, etc. For example, if you plan to PMA a single run of 100 simple parts vs multiple runs of 100 complex parts, your costs will be greatly different. However, once you have obtained a PMA, any future part development will have a reduced cost.
and after what can be an extended and expensive process you have an STC,
Again, very subjective on several levels. There is no one size fits all here. For example, given there are different types of STCs, you can have some STCs that are merely a paperwork exercise vs STCs with a long physical certification process.
But the first question most STC or even PMA applicants ask themselves is if they even need an FAA design approval and/or production approval which is what an STC and PMA actually are.
Some vendors develop aircraft parts without either and let the buyer/installer determine how to install them on their TC’d aircraft. And to ensure they don’t violate Parts 21.9 or 3.5, those vendors will designate them as “experimental” parts or use a product code like Wag Aero does.
which you own forever, barring competitors from using your data,
Your approved data, yes. Unfortunately, STCs do not prevent someone from copying your idea and getting their own approved data. Nor would a PMA stop me from looking at your PMA product, find a similar OTS part and install it on an aircraft as an alteration.
To sell your new product, you need a PMA. The cost to maintain said PMA ain't cheap.
Not necessarily. As mentioned above it depends on what your part is, what your market is, etc. Some vendors have been successful providing parts without a STC, PMA, or TSO. But even if one were to obtain one of those approvals, the upkeep of that approval is again subjective to the part, etc.
and there Is the never ending insurance and product liability risks.
Which has zero to do with the FAA.
When volumes are low, it may not pay to sell any products. That's a barrier to entry.
Except that is a market barrier. All the aviation vendors I’ve been involved with over the years determined market volumes, market volatilely, ROI, etc. well before they started any part production or FAA part approval processes. That is business 101.
For example, the reason you see very limited new part options for Part 91 recreational aircraft is simply because that market is stagnant and to some is in a state of decline. Where is the financial incentive if there’s no growth potential? And so on.
The FAA recognized this and tried to address it with NORSEE,but it doesn't go far enough, IMHO.
They recognized this long before NORSEE and the other policy memos they released to streamline equipment installations. For example, AC 23-27 was issued in 2009 but there were others going back to the 90s. And the main reason most of these FAA efforts lose traction at the private Part 91 level is that these owners do not embrace these efforts in any meaningful numbers for a variety of reasons, ie., the market does not respond nor is it viable.
