Flight Testing of the FAA OBIGGS On the NASA 747 SCA William Cavage AAR-440 Fire Safety Branch Wm. J. Hughes Technical Center Federal Aviation Administration International Systems Fire Protection Working Group Place de Ville Tower C Ottawa, Canada February 14-15, 2005

Outline Background OBIGGs Installation Goals and Objectives System Architecture OBIGGs Installation Instrumentation and Summary of Testing Results OBIGGS Performance Fuel Tank Inerting Summary AAR-440 Fire Safety R&D

Testing Goals and Objectives Study the FAA dual flow methodology as well as a variable flow system methodology and expand upon existing system performance data Develop/validate system sizing data Validate previous in flight inert gas distribution modeling done by FAA Additionally study CWT flammability in flight (not discussed in this presentation) AAR-440 Fire Safety R&D

OBIGGS - System Architecture Uses Air Separation Modules based on HFM technology Accepts hot air from aircraft bleed system Cools, filters, and conditions air using heat exchanger air from external scoop Air is separated by ASMs and NEA is plumbed to output valves to control flow OEA is dumped overboard with H/X cooling air through dedicated scoop under aircraft on pack bay panel System configured to operate in a dual flow methodology for some tests and a variable flow methodology for others Prototype OBIGGS components wired to a system control box by a single cable AAR-440 Fire Safety R&D

OBIGGS - System Installation System installed in empty pack bay area by FAA as designed by Shaw Aero Devices with the System Interfacing Mounted with 6 brackets to the fairing super structure Gets bleed air from small T put in 8” main bleed duct NEA deposited in bay 6 of the compartmentalized (6 bays) CWT with no cross-venting in tank (vent system half blocked) Two exterior panels replaced with FAA test article panels which have the H/X scoops installed System controlled by box in cabin Manually controlled ASM air temperature AAR-440 Fire Safety R&D

FAA OBIGGS Installation Drawing in 747 Pack Bay AAR-440 Fire Safety R&D

Photos of FAA OBIGGS Installation on 747 SCA AAR-440 Fire Safety R&D

Instrumentation and DAS OBIGGS system pressures and temperatures same as in previous testing Eight sample locations within the CWT in six different bays FAA (OBOAS) utilized Aircraft altitude measured by pressure transducer Measured flammability of CWT and #2 wing tank Laboratory DAS utilized Simple out-of-the-box solution AAR-440 Fire Safety R&D

Instrumentation Racks Mounted in NASA 747 SCA Existing Power Distribution Rack OBOAS DAS Rack NDIR Analyzer FAS Rack AAR-440 Fire Safety R&D

Flight Test Plan Operated system in dual flow configuration for first test and in variable flow configuration for remainder of testing Did a series of 7 flight tests ranging from 2 to 5 hours totaling approximately 30 hours of flight time Validated the two-flow mode methodology and studied maximizing system flow during top of descent Studied effect of CWT fuel on inerting and demonstrated the ability of a system to reduce the flammability exposure of an aircraft Examined the effects of long cruise times on system performance Examined existing fleet flammability with baseline flammability testing AAR-440 Fire Safety R&D

747 SCA Results - System Performance System performed as expected with predictable ASM dynamic characteristics Less bleed air pressure in cruise and greater deviations The data does not indicate deviations decreases the system efficiency AAR-440 Fire Safety R&D

747 SCA Results - System Performance Correlation of pressure and flow for low flow mode as expected with test 1 data slope deviating from test 2 and 4 slope somewhat Probably an indication of system being operated (warmed up) before start of flight test As fiber gets warmer it becomes more permeable but more selective AAR-440 Fire Safety R&D

747 SCA Results - System Performance Correlation of pressure and flow for high flow difficult to see because of constantly varying ASM pressure Some data illustrates excellent correlation because of the stabilization of system temperature Other data illustrates wide range of results probably due to constantly changing ASM conditions due to jockeying ASM pressure Delays in [O2] Instru-mentation make this even more difficult AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Evolution of oxygen concentration from bay-to-bay typical of previous scale model and ground testing Oxygen concentration spike in bay 1 greater than in modeling exercises (spiked to 19.5%) Obtaining higher NEA flows with a wider orifice (variable flow valve) at the top of cruise more difficult than anticipated due to high back pressure on NEA output at times AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Average ullage oxygen concentration data illustrates system worked as expected for a approximately 42 minute descent Resulting ullage oxygen concentration about 11% Average spiked to 13.5% oxygen by volume Descent had a 10 minute hold AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Comparison of average ullage oxygen concentration for 4 tests with different descent profiles that have similar features Main parameters that effect the average ullage oxygen concentration are descent time and change in altitude AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Comparison of peak worst bay (bay 1) oxygen concentration for same 4 tests illustrates very similar relationships Average peaks correlate directly with worst bay peaks in oxygen concentration Worst bay peak tends to be sensitive to average peak oxygen concentration AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Comparison of oxygen concentration distribution for same 3 tests with similar descent profiles illustrates pattern Have to extrapolate test 1 because does not have 42 min descent Greater flow tended to allow better distribution but had little if any effect on the resulting oxygen concentration 46 Min Descent 42 Min Descent 42 Min Descent AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Tank oxygen concentration evolution after landing shows previously measured relationship Worst bay [O2] goes from 13% to 12% in one hour After 3 hours band of oxygen concentration is about 1% Increase in average ullage [O2] probably not real Increase in average ullage [O2] AAR-440 Fire Safety R&D

747 SCA Results - Fuel Tank Inerting Tank oxygen concentration change overnight illustrated expected results Line does not reflect Expected trend Overall average ullage oxygen concentration rose about 1% Bay oxygen concentrations completely equilibrated AAR-440 Fire Safety R&D

Summary FAA dual flow OBIGGS concept validated and variable flow methodology studied Lower ASM pressures will give less NEA production from OBIGGS but wide varying system aircraft parameters had no noticeable adverse effect on the resulting system performance Increasing flow during the bottom of descent (variable flow valve) had little effect on the resulting oxygen concentration but did increase inert gas distribution in a compartmentalized tank AAR-440 Fire Safety R&D

Summary Fuel tank inerting results illustrated expected relationships between system performance and ullage oxygen concentration Dual flow methodology allows for relatively small OBIGGS, when sized correctly, to provided complete flight cycle protection for virtually all expected commercial transport airplane missions Inert gas distribution accomplished easily in single bay tank while differences in multiple-bay tank [O2] tend to equilibrate readily Fuel load effected ullage oxygen concentrations very little if at all Proper sizing of inerting system will tend to minimize peak worst bay oxygen concentrations in multi-bay CWTs Inert gas dispersion from CWT during long ground operations and overnight sits does not appear to be a problem AAR-440 Fire Safety R&D