Fire suppression in aircraft by solid propellant gas generators: Fid-Bau Portal

Fire suppression in aircraft by solid propellant gas generators

Lemke, Jens / Beuermann, Rainer / Meyer, Michael

This document describes an approach for an alterative aircraft fire suppression system using Solid Propellant Gas Generators. Such gas or aerosol generators are commonly available on the market from multiple suppliers, but since these are designed for ground based applications several modifications are necessary to meet the aeronautical requirements. Based on existing systems the potential use of this technology for aircraft cargo hold fire suppression is sketched. Then fundamental principles of the fire suppression mechanism by Solid Propellant Gas Generators producing aerosols are described. The investigations undertaken in the frame of this project have shown that the use of solid propellant aerosol generators would be generally feasible for an application as fire suppression system in an aircraft cargo compartment. According to tests, studies and certifications that the supplier provided, it can be concluded that the suppressant is non-toxic and not harmful for workers in the cargo compartment in normally un-occupied areas. According to the supplier the tested generators can operate in a temperature range from -50 °C to +250 °C, they are already proven for a temperature range from -54 °C to +54 °C for other application. The tests performed with a specific generator setup indicate that they can meet the regulatory performance requirements and a homogeneous distribution is obvious. However an appropriate method for measuring the concentration must be defined. Furthermore corrosion studies with the samples that are taken during the tests have shown good results. Since the minimum design concentration to meet the performance test requirements is still not determined and the generators are not optimized for an aircraft application, the system mass is still twice as high as the actual system. Moreover the tests revealed a high contamination of soot in the protected enclosure. This is supposed to emerge by the rapid cooling of the aerosol stream within the generator avoiding an adequate phase change.