Check the listing for details. Cylinder Head Temperature Indicator, Type B-9, US Army Air Corps WWII. Condition: Used. Listed at 50.00 USD. The Cylinder Head Temperature Indicator, Type B-9, was a crucial piece of equipment used by the US Army Air Corps during World War II. This indicator allowed pilots and mechanics to monitor the temperature of the cylinder head to ensure optimal engine performance and to detect any potential issues before they became major problems. Its design and functionality reflect the significance of precise monitoring and maintenance in military aircraft during this historical period.