Low Cost, High Reliability Fire Detection System for Aircraft Applications

A low cost approach to fire detection is proposed which utilizes color ad CCD Machine Vision Flame Detectors (MVFDS) and a new infrared imaging MVFDS to monitor engine overheat/burn-throughs as a possible replacement for thermal wire. It may also have flame detection potential. The IR focal plane array consists of over 80,000 microbolometers on a SI chip which can resolve small temperature differences on the surface of an engine in high temperature backgrounds. This new detector will use four fiber optic cables, vibration protected, interfaced to the chip, routed from the camera in an adjacent bay into the nacelle bay. One detector per engine will serve as four detectors and the four subimages compose a single image which is processed at speeds of 10-30 frames/sec as is now done with color MVFDS. The system has a low LCC, costs less than thermal wire and provides higher benefits of temperature resolution and reliability. A video output to the pilot will also be provided. The color CCD MVFDS will be tested and software developed to simultaneously measure smoke concentration. Blue and red LEDs will be used as emittters in various locations of the camera's FOV. The transmissivity and optical density will be measured as well as ratios of each color intensity. This ability will save the cost of using separate smoke detectors. It is proposed to use the MVFDS to monitor color changes of reflected light due to changes in temperature of thermochromic liquid crystal materials. These inexpensive materials change color as their surface temperature changes. By measuring color changes of these materials while simultaneously monitoring for flame and smoke, potential overheat and hidden fire conditions can be located and wanrnings given.