The tail boom is semi monocot construction. That means the skin of the boom takes most of the flight loads. It is made up of bulkheads and top and bottom keels. When you look at the boom, you will see rows of rivets that go all the way around the boom. This is where the bulkheads are.
To inspect the boom, most of the work involves doing a visual inspection of the exterior of the boom. Look for loose rivets, corrosion and cracks. You also need to look down the end of the boom to assure birds have not made a nest in the end of the boom.
The transition area at the from of the boom has some inspection panels. You can look in these to get a idea of any corrosion problems with the lower keel.