A C check would cost more than the plane.
It’s tricky. I’m training to become part of a crew member on a C-123K and we do all the maintenance on it ourselves. All the carriers that fly these old propliners do the maintenance themselves as well, meaning they are only paying for labor and parts with no mark-up. For example, a rebuilt R-2800 is going to cost about 50-60k. An entire cylinder (and associated parts) for one of these engines is around $1000-1500. We paid 1200 for a complete cylinder assembly last week after we had a cylinder head crack on us coming back from a show. We have had to replace one engine once in the nearly 20 years we have operated the plane. Our last cylinder change was over 2 years ago as well. Now granted, we an air show bird, so we dont fly that often, but for the most part they are really reliable and dont cost that much to maintain.
However, for the ice pilots for example, there is no plane that can replace their DC-6’s, C-46’s or DC-3’s. And they obviously are still making money with them even through all the expenses or else they wouldn’t have been able to purchase 2 L-188’s and I believe I read they just got a third or have a third one coming.
This is deffinately an area where the system would have to be modified so its not just so cut and paste for every airline type.
Just as the old saying goes, the only replacement for a DC-3… is another DC-3…
I too think it would be awesome to run a bush airline.