@Otters: I had to make an educated guess myself. I used one of the pics you sent me that shows the inside of the engine hood. (I don't think it's made of wood BTW).
Anyway, if you look at the pic you can see that there are 9 "frames" that shape it. That would be the place were you'd find the rivets. Probably the reason the riveting is not very visible is that that surface tends to be quite distorted with bumps in the first place, so the riveting ripples would not be as obvious.
@Simon: about the weathering/texturing. Mostly what you should look for are scratch brushes (I assume you're using Photoshop). I found quite a few free ones on the net, you don't need to buy anything. After that, just play with the settings: make the brushes change size, intensity, with a rather random pattern. Also, use several brushes. If you only use one or two weathering effects, there tends to be a noticeable pattern which doesn't look very good IMO.
These are the tools I use (although my techniques keep changing and hopefully improving). After that, you just need to recreate all of the little things that make an airplane weathered: scratces, chips, riveting ripples, bumps, mud, paint wear, oil streaks, fuel leaks, etc. The more the better.
I hope this helps.