Summer Wing Tank Flamm

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Wing Tank Flammability Testing William Cavage Steven Summer 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 October 25-26, 2006

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Outline Background Test Articles and Methods Scale Fuel Tank in Altitude Chamber Wing Tank Piece in Wind Tunnel Preliminary Result

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Background Recent FAA rulemaking and regulation has focused on improving the safety of the fleet through more thorough systems analysis and ignition source reduction FAA intends to make a rule requiring flammability control of some or all CWTs with an emphasis on inerting system technologies The model being used by the FAA for fleet flammability reduction was developed with CWTs in mind Model uses bulk fuel temperature to determine flammability which may not be as good an indicator of flammability for wings Different secondary parameters (day temperature, fuel height, sun intensity, etc.) effect each tank differently Flight test data caused us to look at our assumptions about wing tank flammability and more advanced model did not replicate data well

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Test Article – Scale Tank in Altitude Chamber Used existing 128 gal aluminum fuel tank in altitude chamber for testing Has extensive array of thermocouples that were repositioned for this testing as well as gas sample ports for THC analysis Has fill port and vent port, as well as inerting and ventilation capability Used altitude chamber to control the ambient temperature of the fuel and tank Fill the tank to the desired fuel load (40, 60, or 80% full) and allow temperature of tank, fuel, and chamber to equilibrate Used a radiant heater to heat the top of the tank, which in turn heats the ullage and fuel

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Block Diagram of Wing Tank Flammability Test Article

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Test Article – Wing Piece in Wind Tunnel Goal of experiment is to examine the cooling effects on wing tank temperatures and fuel vapor concentrations associated with air flow over the wing tank due to aircraft taxi/take-off Effects will be quantified for use in future modeling work

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Test Article – Wing Piece in Wind Tunnel Outboard section of 727 wing containing the surge tank has been mounted in the low-speed section (max air speed of approximately 150 mph) of the FAA’s wind tunnel facility Surge tank is instrumented with 12 thermocouples and a hydrocarbon gas sampling probe Wing section mounted such that it can be rotated to represent appropriate angle of attack Radiant heaters will be used to heat top of wing prior to startup of wind tunnel

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Test Article – Wing Piece in Wind Tunnel

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Results - Preliminary Preliminary testing shows large increases in flammability with top heating but takes time to generate vapor (F.P. 115) Top fuel temp 3-5 deg higher than bulk avg. Altitude effects very significant on the flamma- bility in this configuration This was not observed in flight test 29% Higher Than Isothermal Temp

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Completed initial block of tests using scale aluminum fuel tank in our altitude chamber Examined the effects of fuel height and tank top temperature Compared top heating data with isothermal data Plan to do additional tests to make direct comparisons to bottom heat and examine top cooling effects with altitude Wind tunnel tests are scheduled to begin next week Work Status