Fundamentals of Aircraft Instruments, US Army TM 55-412, Nov 1968

This an original hard copy technical manual, TM 55-412, published by the US Army entitled Fundamentals of Aircraft Instruments in November 1968.  It covers the development and basic principles of instruments used in the era, including engine instruments, flight instruments, navigation, and aircraft systems. Many of these instruments were common in the US Army helicopters used during the Viet Nam War, including the UH-1 Huey.  

It is in very good condition given its age.  It is about 3/4 inch thick.