Cargo compartment fire extinguishing system

In all large passenger transport airplanes, halon fire bottles are used to extinguish fire in the cargo compartments. Halon as a fire-extinguishing agent, contributes to the destruction of stratospheric ozone in the atmosphere and it is banned in many countries. FAA considers halon 1301 as an effective firefighting agent due to its low toxicity and noncorrosive properties but because it damages the ozone layer, it has been phased out of production. However, it is still widely used on commercial aircraft until a suitable replacement is found. In this paper we will present an alternative approach to using halon 1301 as a fire fighting paradigm. In the proposed method, nitrogen is first extracted from the atmosphere by using the onboard air separator module it is then cooled, and pressurized into the cargo compartments to suppress any fire. Several methodologies can be used to increase the flow rate from the air separator module, to extinguish fire in cargo compartment

Fuel leak detection on large transport airplanes

Fuel leakage has the risk of being ignited by external ignition sources, and therefore it is important to detect any fuel leakage before the departure of the aircraft. Currently, there are no fuel leak detection systems installed on commercial aircrafts, to detect fuel tank leakage, while only a small number of more recent aircraft, have a fuel monitoring system, that generates a fuel leak-warning message in cockpit in the case of fuel imbalance between the tanks. The approach proposed in this paper requires the fuel vent ports on the wings to be replaced with fuel vent valves, which can be controlled to be in open or close position. The fuel vent valve will be in close position, when certain conditions are fulfilled (all the related fuel valves closed, pumps not operating, etc.), the fuel tank ullage area is then pressurized to 4 psi and the rate of change of the pressure is measured over a period. Several experiments have been conducted and, the result show that a continuous fuel leak of one liter per minute can be detected. Further experiments show that if the fuel tank is pressurized to higher pressures, a fuel leak can be detected sooner

Avionics compartment fire extinguishing on the commercial airplanes

In all commercial and non-commercial airplanes, there is no fire detection or fire extinguishing system in the avionics bay. Racks, are cooled by ambient or conditioned air. Each rack will include several circuit boards, which in case of overheat, can burn with the risk of igniting the surrounding components and structures, thus jeopardizing flight safety. It becomes therefore important to provide fire detection and fire extinguishing capabilities in the aircraft avionics compartment. The approach proposed in this paper, extracts nitrogen from ambient air by mean of the Air Separator Module, then nitrogen is routed to the avionics compartment racks, and enters inside the component and extinguishes the fire. The temperature of the nitrogen is adjusted to be around 25°C to prevent thermal shock effects on the circuit boards before being injected in the avionics compartment. A series of experiments conducted, aimed at gathering information by using dry nitrogen under different pressure values to extinguish different size of fire. The analysis of the experiment research showed that increasing nitrogen pressure, resulted in quicker extinguishing time. This is because nitrogen under higher pressure, quickly decrease the oxygen concentration in the air for the fire already in the process of combustion. Nitrogen does not conduct electricity thus cause no short circuits during and after the extinguishing process, therefore, they are ideal for use in the electronic systems