Fundamentals of Aircraft Instruments, US Army TM 55-412, Nov 1968 US Coast Guard a piece of thin metal

a piece of thin metal placed vertically in the center of the glass cover or window

and the PBY5A Catalina Seaplane (which used 2)

as well as the British Avro Lancaster and deHavilland Mosquito bombers

This type of gauge was the primary tool used to lean the large radial engines in service late in the piston-powered aircraft era

and maintenance of more than 30 instrument types

Fundamentals of Aircraft Instruments, US Army TM 55-412, Nov 1968 US Coast Guard a piece of thin metalThis 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