I've discovered in my SimObjects\Airplanes directory, 2 Microsoft FSX default aircraft (DeHavilland_Beaver_DHC2 & DH_Dash8_100) that I can't find in the Aircraft Selection in Free Flight setup.

 

How can I go about getting these planes?

 

Their directories seem complete with aircraft.cfg, .air files, models, sounds, and textures ...

 

There are apparently 3 Dash-8s available, and 3 Beavers.

Dash 8 is not flyable plane, beaver with floats should be though.