http://www.fsalpha.com/home.shtmlThese are flash video tutorials. The top half of the page consists of payware tutorials. If you have money in the bank, go ahead and buy one. That's if you're interested in buying one.
For freeware tutorials, scroll halfway down until you see a flash tutorial about the Helix.
www.onnovanbraam.comThis site provides text tutorials [along with screenshots] on how to understand and use splines, how to make a wheel, and how to make odd-shaped tubes, and how to set up a 3-view image for development.
The site also provides a motherload of 3-view images on human figures, ships, tanks, planes, jets, cars, even weapons, motorcycles.
http://www.suurland.com/This site also provides 3-views as well. But don't use the tutorials, because those tuts are based on a 3D-modeling application that is incompatible with Flight Simulator aircraft development.
http://www.comet-cartoons.com/toons/This site provides tutorials on how to make human figures as well as scripts that are very useful for Gmax. The scripts and tutorials are all based on 3D Studio Max, but Gmax is the same as that one so it's no problem.