De-Icing Pressure Indicator, AN5771-3, B-17, B-24, B-29 Bombers
This is a De-Icing Pressure Indicator for the de-icing system used in WWII US Army Air Forces aircraft such as the B-17 Flying Fortress, B-24 Liberator, and B-29 Superfortress. Made by Electric Auto-Lite with a serial number prefix of AF43, likely made for a US Army Air Force order during 1943. On the B-17G, the indicator appeared on the Pilot's overhead Compass Panel, see illustration from the B-17G Erection and Maintenance Manual in the photos. In the B-24, the indicator was positioned below the co-pilots instrument panel, and on the B-29 it was installed on the flight engineers instrument panel. When the de-icing system is engaged by flipping a toggle switch, the indicator displayed the pressure being applied to the rubber surface de-icer boots along the leading edges of the wings and empennage to dislodge ice which has formed, with a normal indication of 7-10 PSI. Measures 2.25in diameter and ~2in deep.