I also checked the web and saw the same topic about VUSN (or similar anyway). I checked my collection too and I don't seem to have any versions of Mayport. I remember a few years back (2011-2012) when I discovered some of Jim Dhaenens' scenery, there were a few that I couldn't find anywhere, and after heaps of searching all I could find was that for some reason they had been removed from the internet. I always put it down to them being military bases and maybe it had something to do with security. I had a list, which was longer, but these are the ones I still haven't been able to find:
NAS Corpus Christi
NAS Fallon, NV
Barakoma
NAS Lemoore, CA
NAS North Island
NAVSTA Mayport
I do have another version of NAS North Island, but I think it's for FS2004.
There are a lot I do have too, so not sure why some have disappeared. In any case the ones I do have are all excellent sceneries. The missing ones are one of the reasons I have become fairly obsessive about downloading addons, as you never know if they'll still be there afterwards.
Cheers,