Cargo Bay Fire Protection with a Fuel Tank Inerting System William Cavage AAR-440 Fire Safety Branch Wm. J. Hughes Technical Center Federal Aviation Administration International Systems Fire Protection Working Group Tropicana Casino and Resort Atlantic City, NJ November 1-2, 2005

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Outline Background Test Article and Method Preliminary Results Summary

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Background FAA developed a proof of concept inerting system to inert the CWT of classic style Boeing model 747 –FAA intends to make a rule requiring flammability control of some or all CWTS with an emphasis on inerting system technologies Potential for using these systems to expand fire protection needs to be explored –E&E bays, wheel wells, dry bays, and hidden overhead areas for example –This project focuses on using the generated NEA to replace the cargo bay fire suppression make up agent

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Background – Cargo Bay Fire Suppression Cargo bay fire suppression is done in two parts –First part dispenses large volume of agent rapidly to suppress fire –Second part dispenses a fixed amount of agent slowly, based on the aircraft operational capability, to make up for cargo bay leakage It remains to be seen how useful an OBIGGS designed to inert the CWT of an aircraft would be for this purpose –Sizing would probably be different –Different design requirements, and certification requirements –Cert requirements still not firm

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Test Article Used existing 747SP ground test article to study the issues associated with cargo bay inerting –Already has inerting system installed with associated instrumentation Plumbed the OBIGGS to inert the aft cargo bay with a simple deposit system –Can deposit 1-6 ASMs amount of NEA of varying purity Eight gas sample locations in cargo bay used to continually measure oxygen concentration during testing –Also can measure flow and purity of NEA being deposited –Multiple temperatures and pressure in aircraft available

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Rendering of Cargo Bay with Gas Sample Locations - Gas Sample Locations o o o o o o o o o

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Test Methods Preliminary testing focused on finding air leak locations, rates, and effects –Discovered large bleed air leak which caused testing delay –Cargo bay heat leaked some even when off Examining inert gas distribution issues –Previous work indicated rectangular bays have easy distribution requirements –Examine leakage effects on distribution Focus of work is to determine the sizing (amount of NEA generated) of a CWT inerting system is relevant to cargo bay fire protection –Using static performance data and single bay inerting model to evaluate ability of inerting system given cargo bay fire conditions

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Results - Preliminary Preliminary testing had difficult time reducing the oxygen concentration in the cargo bay below 12% –Found large bleed air leak due to cracked duct Existing inerting models used to evaluate the problem and find size of leak –Model validated the size of the cargo bay and instruments found location of leak

Cargo Bay Inerting ____________________________________ AAR-440 Fire Safety R&D Test article is modified and ready to study cargo bay inerting Bleed air leak has caused project delay but allowed us to develop a cargo bay inerting model that takes into account air leakage Need information from industry to study feasibility of using an FRS for cargo bay fire protection –Need representative flight profile complete with bleed air pressure schedule of a cargo fire event Testing will continue when air leaking issues are resolved Summary