Two years after the federal government took over all airline passenger and baggage screening following glaring lapses in security, some airports are considering a return to privately employed screeners. The Transportation Security Administration will start accepting applications from airports Friday for what could be another major change in the way aviation security is handled in the wake of the Sept. 11, 2001, terrorist attacks. Some airport officials are unhappy with the current federal system, saying it doesn’t allow enough work force flexibility and has caused long waits at security checkpoints. A TSA spokesman says that four or five airports are really interested in going private, and another 20 to 30 have expressed some interest. Here’s the story.