Book 8 in the Brotherhood of War series. This is an umpteenth reread, though I see I haven't read it since I started this book log.
This one is kind of set off to the side of the mainstream story (the author clearly decided to extend the series when it was so successful). Johnny Oliver (a new character) comes back from Vietnam and ends up being assigned as General Bellmon's aide (Bellmon is an ongoing character from the beginning of the series). Bellmon is commanding Fort Rucker, the Army Aviation Center. This is largely about the development and test of the Airmobile Division, and the politics surrounding that and the Chinook CH-47 helicopter. The time period overlaps the uprising in the ex-Belgian Congo, and that's peripherally involved.