IASFPWG – Ottawa, Canada Limiting Oxygen Concentration (LOC) Work Update International Aircraft Systems Fire Protection Working Group Ottawa, Canada July 8 - 9, 2003 Steve Summer Project Engineer Federal Aviation Administration Fire Safety Branch, AAR-440

IASFPWG – Ottawa, Canada LOC Testing – Work Update  Conducted sea level (SL) testing with a J-57 engine igniter  Conducted SL testing with a short duration arc from oil burner transformer  Measured voltage/current at spark gap and calculated energy for both spark/arc generator  Composed report of all data generated to date with the various ignition sources (AR-02/79)— due out shortly

IASFPWG – Ottawa, Canada Facilities – Pressure Chamber

IASFPWG – Ottawa, Canada Facilities – Pressure Chamber  353 ft 3 pressure vessel Working pressure of 650 psi. Attached vacuum pump used to evacuate chamber to reduced pressures seen at altitude. Not capable of simulating temperatures seen at altitude.

IASFPWG – Ottawa, Canada Facilities - LOC Test Article  9 ft 3 simulated fuel tank placed inside of vessel equipped with: Bottom surface heaters. 12 thermocouples. 2 piezoresistive pressure transducers mounted behind sintered porous metal discs. Interchangeable pressure relief mechanism.  ¼-in. aluminum plate.  Foil diaphragm. Spark gap.  2 tungsten electrodes with controllable gap alignment and spacing

IASFPWG – Ottawa, Canada Apparatus – LOC Testing

IASFPWG – Ottawa, Canada Apparatus – LOC Testing

IASFPWG – Ottawa, Canada Ullage Vapor Sampling

IASFPWG – Ottawa, Canada LOC Testing Apparatus  Ignition Sources 10 kV Oil burner transformer operating at ~30 mA provided both long (~1 second) and short (~0.1 second) arcs J-57 Engine spark igniter provided a very short (~175  second) spark 3" x 6" x 1" metal block heated by two cartridge heaters to temperature in excess of 1400°F  Energy Measurements Voltage and current traces were taken using a HV and current probe at the spark gap connected to oscilloscope

IASFPWG – Ottawa, Canada Oil Burner Transformer Voltage & Current Traces

IASFPWG – Ottawa, Canada Test Program  JP-8 LOC Tests Mass Loading ~ 4.5 kg/m 3 Ambient pressure corresponding to altitudes of 0, 10, 20, 30 and 38 kft Ullage oxygen concentrations ranging from 21% to below the determined LOC Tests conducted with two different pressure relief mechanisms  ¼-in. aluminum plate – Ignition = movement of plate  Foil diaphragm –Ignition = rupture of foil

IASFPWG – Ottawa, Canada Test Program (cont.)  Tests conducted initially at all altitudes with long duration oil burner transformer arc (~0.5 J, 1 s)  Subsequent tests conducted with various ignition sources at sea level in effort to determine any variation of LOC with ignition source Short duration oil burner transformer arc (~0.08 J, 0.1 s) J-57 Engine igniter spark (~0.5 J, 175  s) Hot surface vapor ignition (HSVI)

IASFPWG – Ottawa, Canada LONG DURATION OIL BURNER TRANSFORMER ARC TEST RESULTS

IASFPWG – Ottawa, Canada Aluminum Plate Relief Mechanism

IASFPWG – Ottawa, Canada Foil Diaphragm Relief Mechanism

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada J-57 ENGINE SPARK IGNITER TEST RESULTS

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada

IASFPWG – Ottawa, Canada SHORT DURATION OIL BURNER TRANSFORMER ARC TEST RESULTS

IASFPWG – Ottawa, Canada Short Duration Test Results

IASFPWG – Ottawa, Canada HOT SURFACE VAPOR IGNITION TESTING (HSVI)

IASFPWG – Ottawa, Canada HSVI Testing  Test Setup Setup was identical to the spark/arc ignition testing. In place of spark, a 3" x 6" x 1" metal block was heated by two cartridge heaters for use as the ignition source. Conducted only at sea level conditions.

IASFPWG – Ottawa, Canada HSVI Test Results  At 21% O 2, ignition was achieved at a hot surface temperature (HST) of approximately 1350ºF.  A half-dozen other tests were conducted at O 2 concentrations ranging from ~11.5 – 14%. Though some “puffs” of smoke could be seen as the HST approached ~1200º F, no ignitions occurred.  Therefore, HSI within the fuel tank provides no more of a threat than spark ignition.

IASFPWG – Ottawa, Canada Conclusions  LOC at SL through 10 kft is ~12%, increasing linearly through 40 kft to ~14.5%  Little effect seen on SL LOC due to ignition source Long duration arc: 12% High powered spark: 12.3% Short duration arc: 12.9% HSVI: ??

IASFPWG – Ottawa, Canada Future LOC Work  Currently working with a very high energy spark (>20 J) 120 Vac, 400 cycle hard short to ground Will be placing in the tank within the next week. To commence testing shortly thereafter.  Technote AR-02/79 due out shortly