do TR expire?
 

Just wondered if anyone knows wether a type rating from a specific aircraft expires or stays current indefinatley? I am talking along the lines of a 737 or A321 Rating.

Depends on your NAA.

As the Scotsman pointed out, it depends on the licensing authority. If I remember correctly, with FAA the TR never expires. EASA gives you five years. But you do need to have a current sim check (6 months for public transport, 12 for private) and take offs / landings.