Descent 3 was always kind of buggy for me, and seemed rather sensitive to changes in my system (why I do not know) all I can suggest is doing a clan install.
You could also make a Game extension set in the extensions manager, with the basics extensions (the Mac's name for Drivers) to get the game to play which will be (all game sprockets, OpenGL, QD3D, Quicktime, CD/DVD reader, USB and HID extensions, and anything to do with Opentransport).
The game is a little old (but still looks and plays great) so it might be incompatible with 9.2.2, I've emailed graphsim (the Mac Deveoper/porter of the gsme I believe )about probs I had with the game in past, but with no success, but I'd give them a try if nothing else works.