Gyro Flight and Directional Indicators Technical Manual TO 30-15A-4

This is an original WWII-era Technical Manual for gyroscopically-operated Flight (Horizon) Indicators and Directional Indicators used across most bomber, fighter, and transport aircraft of the US Army Air Force and US Navy. 

This 140-page, loose-leaf unbound manual reviews the basic information as well as in-depth technical information on both instruments, including disassembly, repair, and maintenance. It is full of illustrations and diagrams. The cover page is missing but the rest of the pages are present and intact.