Ground Based Fuel Tank Inerting

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Auxiliary Tank Testing and In-Flight Facility
Development
Michael Burns Fire Safety Research Federal
Aviation AdministrationWilliam J. Hughes
Technical Center
November 15th - 18th, 2004 FAA Fire and Cabin
Safety ConferenceLisbon, Portugal
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Background

• Three major accidents involving center wing tanks
  (CWT)
• March 2001, Thai Airways International, Boeing
  737-400
• July 1996, TWA flight 800, Boeing 747-100
• May 1990, Philippine Airlines, Boeing 737-300
• FAA seeks its flammability reduction rule since
  1997
• Two unsuccessful industry rulemaking advisory
  committee working groups
• FAA developed a demonstration fuel tank inerting
  system
• Installed and operated on several test transport
  aircraft
• Uses air separation modules (ASM) and a dual /
  variable flow methodology
• Unique methodology allowed for simple,
  lightweight, reliable onboard nitrogen generation

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Center Wing Tank Inerting Research

• Recent CWT testing with NASA, Airbus and The
  Boeing Company
• FY01- FY04 testing and validation of CWT inerting
  methodology
• In-flight measurement of fuel tank flammability
• Excellent results but little work has been done
  to study the affect of auxiliary tank operations
  on CWT
• New research facility at FAA WJH Technical Center
• Construction scheduled for winter, 2005
• Facility being designed to study fuel tank
  inerting and flammability
• Real-time CWT operational simulation, full-scale
  testing, and model validation

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Center Wing Tank Inerting Facility
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Center Wing Tank Inerting Facility cont.

• Initial use to further study the affect auxiliary
  fuel transfer has on an inert CWT
• Ullage oxygen concentration changes due to fuel
  transfer
• Purge cycle effects once the auxiliary tank is
  empty
• Auxiliary tank refueling effects
• Facility will house a full-scale CWT and
  auxiliary fuel tank
• Simulate altitude as well as engine fuel burn
• Thermocouples, pressure transducers and gas
  sample ports for gas analysis to allow for
  testing
• Measure nitrogen generating system parameters

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Facility Overview
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Facility Overview cont.

• Approximately 26 x 40
• Interior Communication Signal Raceways
• Pumps (3)
• Vacuum
• Hi-capacity pump with closed loop cooling system
• Capable of simulating a 40,000 foot altitude
  (approx. 2 psia)
• Fuel (P1) Electronically Controlled, Modulating
• Engine fuel burn simulator
• Variable frequency drive fuel flow controller
  simulates taxi, take off, climb, cruise descent
• Fuel flow meter with digital output
• Capable of flowing 85 GPM maximum fuel flow.
• Fuel (P2) Fixed
• Used to refuel the CWT / aux. tank when required
• Plumbed to a 10K gallon fuel vault

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Facility Overview cont.

• Control Room
• Environmentally controlled
• Houses all the controls, analyzers, computer and
  data acquisition equipment
• 8 x 8, mounted on a raised concrete slab
• Safety Features
• Spill Protection Containment pit with sump
• Foundation contains curbing that is approx. 14 x
  24 x 18
• Approximately 500 cubic feet of volume to contain
  any accidental spillage of fuel
• Fire protection
• Over pressure relief panel system

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Facility Overview cont.

• Vacuum pump evacuates chamber
• Altitude controller
• PID Controller
• Modulating Valve
• Pressure Transducer

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Facility Equipment 737 CWT

• Tank origin
• Salvaged from an Air Canada aircraft in March
  2003
• Tank Dimensions / volume
• Approx 12 x 14 x 3 (or 500 CuFt in volume)
• Reinforcing the CWT
• Exterior bracing was applied around the tank
  structure and fastened to the tank wherever
  possible
• Columns were installed in each bay internally to
  offset compression forces exerted on the tank
  while applying a vacuum

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Facility Equipment cont. 737 CWT
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Facility Equipment cont.737 CWT

• Vent configuration
• Internally the tank is vented in the most forward
  bay as well as the aft bay
• The left right vent stringer was modified with
  a flange connection
• These 2 connections will be joined together with
  plumbing and routed to the facility vacuum system
• Engine burn simulation fuel feed tubing
• Facility tubing will be tied into the fuel boost
  pump feeds on the tank

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Facility Equipment cont.737 CWT
Left Fuel Feed Tubing (Bay 3)
Right Vent Tubing (Bay 2)
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Facility Equipment cont.Auxiliary Fuel Tank

• Tank origin
• US Airways surplus auxiliary fuel tank
• Tank Dimensions / volume
• Approx. 8 x 4 x 3
• Approx. 475 Gallons of fuel
• Single tank configuration
• Also known as a Master Fuel Cell
• Contains a dry bay that houses all the valving
  associated with the system
• Cabin Tube
• The fuel cell is pressurized during flight using
  cabin pressure
• In facility, shop air used to simulate normal
  tank operation

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Facility Equipment cont.Auxiliary Fuel Tank
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Instrumentation 737 CWT / Auxiliary Tank

• Thermocouples
• All thermocouples are T type
• 25 total installed throughout the CWT
• 4 total installed throughout the Auxiliary Fuel
  Tank
• Gas sample tubes (FAS, OBOAS)
• All sample tubing is made up of PFA material and
  ¼ in diameter
• 6 total mounted throughout the CWT
• 2 total mounted throughout the auxiliary fuel
  tank
• NEA Inerting Manifold
• Single injection nozzle made of PFA tubing

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Instrumentation cont.737 CWT / Auxiliary Fuel
Tank

• CWT location of penetration fittings
• NEA
• Thermocouples
• Oxygen / FAS Sample Return Fitting
• Hi Level Float Valves
• Auxiliary Fuel Tank Transfer / Vent Flange
• Oxygen / FAS Sample Fittings (6)

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• Instrumentation cont.737 CWT

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Instrumentation cont.Auxiliary Fuel Tank
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Future Work

• Facility will be a key tool for continued fuel
  tank inerting and flammability research
• Study the affect varying surface temperatures
  have on flammability
• Potential industry tool to validate new inerting
  systems and methodologies
• Use facility to validate a variety of models for
  studying fuel tank inerting and flammability