Abstract: A system for detecting an overheat condition in aircraft preferably includes two control units each connected to eight thermal imaging modules. The thermal imaging modules monitor the cargo by for an overheat condition and if any module detects an overheat condition, the control unit verifies the overheat condition and then triggers an alarm. The control units execute routines to monitor and test their operational status and that of each thermal imaging module. The control units are connected to the aircraft electronics to indicate the location of an overheat condition or any malfunctioning control units and thermal imaging modules. The thermal imaging modules are identical to each other and include an infrared detector, a rotating optical assembly, threshold circuitry and a motor. The optical assembly is rotated by the motor to provide the detector with a conical field of view. The optical assembly focuses the radiation in the cargo bay on the infrared detector.

Abstract: An optical fire detection system that uses cosmic radiation or a radioactive source to test whether the ultraviolet light detector tube operates properly and includes self test logic to independently verify that the detector electronics are functioning properly. A high voltage is applied across the ultraviolet light detector tube to produce pulses of current when radiation is present. A pulse rate discriminator circuit measures the current pulses and outputs a fire signal if the pulse rate is equal to or greater than the pulse rate produced by ultraviolet radiation from a fire. A background count circuit also measures the current pulses from the ultraviolet light detector tube to test whether the ultraviolet light detector tube is operational. At least one current pulse should be detected within a specified time because the detector tube senses cosmic radiation or radiation from the radioactive source.