I have constructed the level 2 chopper, but can't seem to choose it. Still level 1 is "equipped". What do I need to do?

In ACC, go to customize helicopter.

I had trouble with this too

The ACC? Being in the helicopter you mean?

@voightkampff: yes, the ACC is the Air Command Center.

Getting upgrades delivered to you while you are out on missions doesn't update your loadout to new level gear. Perhaps it is the same with helicopter upgrades? As others have said, changing back in the helicopter fixed this for me.

On one hand, I guess that makes sense since the ACC is where you customize everything else. On the other hand, being in the chopper as it's flying seems like a bad time to be making modifications to it.

@bbalpert: you just blew my mind. That didn't even occur to me