No, not normally. Most services train in the T-6 Texan II first, so you'll get a comm asel/helo w/IR. In the Navy and Marines at least, there are no restrictions or caveats to transitioning to a fixed wing platform after your first helo tour, whether that is teaching in the T-6, station pilot in the C-12, or even switching communities to a new airplane. It is generally uncommon and frowned upon career wise, but the military will teach you how to fly whatever they need you to fly.

BMD94 thanks for the info. I think I apply for a regional out west when I get ready to go terminal. Any luck I will not spend too long there before going to a Major. I read somewhere JetBlue counts helo time once you meet their 500 ME Turbine time. Anyone see or hear about that?