Fuel Flammability Update

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Fuel Flammability Update

• International Aircraft Systems Fire Protection
  Working Group
• Phoenix, AZ
• March 26 - 27, 2003

Steve Summer Project Engineer Federal Aviation
Administration Fire Safety Branch, AAR-440
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LOC Testing Work Update

• Compiled a more complete set of spark ignition
  data at sea level conditions at a range of THC
  concentrations and oxygen concentrations at and
  around 12.
• Plotted results both as a function of altitude
  and as Fuel Concentration Vs. O2 Concentration at
  request of Boeing/Dr. Shepherd.
• Conducted a series of sea level hot surface
  ignition tests.
• Still no ignitions occurring below 12 O2.

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Facilities Pressure Chamber
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Facilities Pressure Chamber

• 353 ft3 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.

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Facilities - LOC Test Article

• 9 ft3 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.
• Ignition source.
• 2 tungsten electrodes powered by 10 kV
  transformer operating at 20 mA, providing 200
  J/s

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Apparatus LOC Testing
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Apparatus LOC Testing
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Ullage Vapor Sampling
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Test Program

• JP-8 LOC Tests
• Mass Loading 4.5 kg/m3
• 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

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Hot Surface Ignition (HSI) Testing

• Purpose
• To determine if the LOC determined by spark
  ignition testing (12 O2) was also sufficient to
  protect against ignition from some hot surface
  existing within the tank.
• Test Setup
• Setup was identical to the spark 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.

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HSI Testing - Results

• At 21 O2, ignition was achieved at a hot surface
  temperature (HST) of approximately 1350ºF.
• A half-dozen other tests were conducted at O2
  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.