Originally Posted by JustAnothrWindScreen
It is my understanding that nothing prevents the thrust reversers from being deployed in the air other than the pilots not doing that.
Yes, you grab hold and pull them up and you'll be in reverse when airborne. The thrust reverser isolation valve closes to block system pressure when the ground shift is in the flight mode but the accumulator is there to open them up for you...the slip stream will do the rest.
That's why you pull c/b s-28 or t-28 for three seconds when you get a reverse accumulator low message/light in flight. To bypass ground shift, open the isolation valve and allow sytem pressure to briefly recharge the system.