I don't understand this. Why does the owner's plane get moved from standard category to "special," if the STC allows the owner to work on any 150/152 that he subsequently owns without having to STC that aircraft to special? What impact does the STC have on market value of the airplane when it comes time to sell? Can the aircraft be moved back to the standard airworthiness certificate at a later time? I believe Canada has a similar program and I seem to recall the airplane takes a hit when it comes time to sell.
TOPCAT recertifies the airplane in the Primary Category. This was (in my view) the FAA's first attempt at Light Sport Aircraft. Unfortunately, it (along with the Recreational License) never took off. No pun intended.
A Primary Category aircraft is one that is simple enough to allow the qualified owner to perform more tasks than currently allowed. To work on a Primary Category plane, one must receive proper training. Thus, the 'STC' on the person. This is not a blanket rating, however. The current or subsequent aircraft must be in the Primary Category for the 'STCed'-owner to be legally able to work on them.
Part of the expense of the TOPCAT course, in addition to the training, is an extensive annual inspection of the plane to certify it in the Primary Category. However, it remains a certified plane and can be converted back to Standard (or Utility) category by a subsequent A&P/IA.
This is different than the Canadian model. Their method is not to change the airplane's category, but to decertify it entirely. Indeed, X's are stamped over the engine and airframe serial numbers to reinforce that fact. For most intents and purposes, it becomes much like a homebuilt experimental.
While this offers some great freedoms as far as who can work on the plane and what materials they may use, it also comes with liabilities. One, the FAA doesn't allow such planes to come into US airspace - homebuilts are inspected and certified by the FAA/CAA, but these planes are not. Two, resale is an issue. And three, it's a one-way trip. It's next to impossible to recertify such a plane since, in effect, you have to re-prove that every single nut and bolt meets certified standards.
While I like the idea of TOPCAT, for me the list of approved repair items is still too short. It's more a problem of FAA bureaucracy. For example, Rick Hestilow had a very hard time getting valve cover gasket replacement added as an approved task. The FAA types didn't like the idea of non-mechanics opening up the engine. Rick argued that if the gasket repair was faulty, then the engine would leak oil. However, exhaust gaskets (which they had already approved), if done wrong would leak fire! They grudgingly agreed and added the item to the list.
And that's the problem - they approve specific tasks, rather than defining abilities. It's like the current list of Owner Approved Maintenance. One can change a tire or spark plugs, but is not allowed to change an air filter. Never mind that one has demonstrated the ability to change the filter by virtue of changing tires and plugs. Doesn't matter - air filter is not on the list, therefore it's not allowed.
The TOPCAT program has a list of tasks that require some good abilities, abilities that can easily translate to other parts of the airplane. But since those other tasks don't appear in the list, they can't be done. Too shortsighted and limited in my view.
