The NASA Aviation Safety and Security Program has identified false fire alarms as one of the national problems hindering safe expansion of the U.S. air transportation system. Federal Aviation Administration (FAA) surveys of air carriers found that, for fire-detection systems in remote cargo compartments, there were 100 to 200 false alarms for every warning of an actual fire. False alarms negatively impact safety by causing aircrews and air traffic controllers to needlessly employ emergency fire-mitigation procedures and priority landings on the nearest suitable airfield. Unnecessary emergency procedures compromise the air traffic management system. Flight safety is also affected because aircrews subjected to repeated false alarms may be less likely to quickly and aggressively respond to a warning of an actual fire. To address this problem, a team led by the NASA Glenn Research Center developed microelectromechanical systems- (MEMS-) based sensor technology for aircraft cargo compartment fire detection. This task produced a new commercial product, the Multi-Parameter, MicroSensor-Based Low False Alarm Fire Detection System (MMFDS), which was given a 2005 R&D 100 Award as one of the 100 most significant inventions of the year.
Tin oxide microsensor used for fire detection.
The Glenn-led team, which included Makel Engineering, Case Western Reserve University, and The Ohio State University, departed from the standard fire-detection approach of sensing only for the presence of smoke particulates. With these particulate detection approaches, the presence of dust or condensation aerosols can give a false indication of a fire. Instead, the team developed micromultisensor suites to detect the increase in multiple types of gas species that are emitted by fire at its onset, such as carbon monoxide and carbon dioxide. The fundamental detection approach is to use “orthogonal” sensor technology: different types of sensor systems, which provide different information on the environment, combine so that crew and controllers can better understand the overall condition. This task involves
(1) Measuring multiple parameters associated with a fire, such as smoke in combination with multiple chemical species
(2) Developing fire product sensors (chemical and particulate) that are predominately micro- or nano-based to allow multiple sensors to be integrated into a compact array of reduced size, weight, and power consumption
(3) Advanced processing and control software, forming a “smart” detection system with corresponding fire event modeling
Fire testing In cargo bay of FAA Boeing 707.
Complete system tests conducted at the FAA’s Testing Facility successfully demonstrated this approach. Fires were set in the cargo bay of a ground-based, instrumented Boeing 707; the MMFDS was mounted alongside of a standard commercial system, and the responses of both systems were monitored. The FAA chose this test procedure to check both false alarm vulnerability and fire-detection capability. The results were significant. Over a series of exposures to dust and humidity, the MMFDS had a zero false alarm rate, whereas the commercial system had a 100-percent false alarm rate. Over the entire fire test series, the MMFDS sensed the onset of an actual fire as well as the conventional detector, if not better, and within the standard FAA requirement of fire detection within 1 min. The test demonstrated the complete elimination of false alarms with the newly developed hardware and software system. The new commercial product is now available for fire detection with low false detection.
Find out more about chemical species gas sensors at Glenn: http://www.grc.nasa.gov/WWW/chemsensors/
Dr. Gary W. Hunter, 216-433-6459, Gary.W.Hunter@nasa.gov; Dr. Jennifer C. Xu, 216-433-6669, Jennifer.C.Xu@nasa.gov; and Robert C. McKnight, 216-433-2034, Robert.C.McKnight@nasa.gov
Authors: Dr. Gary W. Hunter, Dr. Jennifer C. Xu, and Robert C. McKnight
Headquarters program office: Aeronautics Research
Programs/Projects: Aviation Safety, CEV, Life Support & Habitation
Special recognition: 2005 R&D 100 Award, Associate Administrators Choice Award (Turning Goals into Reality)
Last updated: October 16, 2006
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