You have been receiving excellent advise in the above Posts!
Most Humans see Birds flying in their natural environment and believe that their Companion Parrots should have the same opportunity. There is also the belief that time in natural Sun light will be healthy for them. Although, there are any number of excellent studies, which present the healthy advantage of natural (unfiltered) Sun Light. There are also great dangers to having Companion Parrot's outside.
Pennsylvania, as with Michigan are 'Raper Rich Environments' (Scott), which means that the number of year around Raper pairs is above two pair per 10 square mile area. Since, different Raper species ranges overlap the number of different Rapers passing over your home could be as high as one pair per day.
Our home is used during mid-late Summer as a flight training range for Red Tail Hawks. Any given day, two Red Tail Hawk families will use our house to train their young at the art of high-speed turning prior to an attack. Over a six week period, we see more than sixteen different families training their young. Free-flying in our backyard is to say the least dangerous for any Bird, let alone a Companion Parrot.
Our DYH Amazon is fully flighted and also a Free-Range Parrot. Although there are areas around our City that as a result of the general openness of the area (large open fields) that one could Free Fly their Parrot. We believe that the much higher likelihood of the loss of our Amazon is just not worth it. With so many excellent products available today, its just not worth it!
If you are interested in your YNA regaining flight, I would recommend going to the top of the Amazon Forum and opening the Thread highlighted in light blue Titled: I Love Amazons -, Start with reading, Getting Your Amazon More Active (Page: 7) First, and than reading, Re-Fledging a Adult Amazon (Page: 4).
As stated as part of SCOTT's Post, you can, by careful and timely clipping your YNA's wing's 'Primary' feathers control the amount of lift and distances of flight.
We have a fully screened-in lower porch what we take our DYN Amazon out in during Spring, very early Summer and mid-late Fall. We also travel with our Amazon weekly, year around (he LOVES riding in the SUV).