Yes, you can build a wood spiral staircase using these plans. Save yourself several big bucks, and make exactly what you need, not what they have. For a real good look at the plans and pictures stop in at http://www.avsupport.com/aviationgraphics/files/stair/Stair.htm
I don't know if HTML will work here, but here goes.
Spiral Stair Plans. If the image or link didn't work, Tell the owner here he needs a repairman.