Hi JAA/FAA pilot,
The JAA proficiency check (PC) is a check to keep the type in your JAR certificate valid. And it is valid for 12 months. If you are working within a european commercial company you have to do a OPC (operational proficiency check ) every 6 month.
But like Gordy wrote, these things doesn't apply to you, with a FAA certificate in a N reg helicopter..
Fly safe, wiisp