An Investigation Into the Causes for the Short Lifetimes of Geiger-Muller Tubes Used in Aircraft Oil Gauging Systems

The causes of failure of the G-M detectors used in the nucleonic oil gauging system of USAF aircraft are presented. Experimental tests performed on several tubes, in simulated aircraft environments, proved that the detectors fail because of a depletion of the halogen quench gas. A variety of surface analyses established that the halogen gas reacted with both the cathode and anode surfaces. On the cathode the halogen bromine attack was always co- located with lead deposits and the only known source of lead inside the counter is from the glass solder used as the tube sealant. Recommendations are made to increase the G-M tube longevity. Implementing these recommendations require only minor modifications to the basic system.