Ground Based Fuel Tank Inerting

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FAA Concept OBIGG System Flight Testing on NASA
747 SCA
William CavageAAR-440 Fire Safety
ResearchFederal Aviation Administration
Systems Fire Protection Working Group Taj Mahal
- Atlantic City, NJ November 4, 2003
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Outline

• Goals and Objectives
• OBIGGs Architecture
• OBIGGs Installation
• Pallet
• NEA Deposit
• Instrumentation / DAS
• CWT
• System
• OBOAS / FAS
• Data Acquisition
• Power Distribution
• Status

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Testing Goals and Objectives

• Prove the simplified inerting concept and
  validate/expand upon existing system performance
  models
• Develop/validate system sizing data
• Validate previous in flight inert gas
  distribution modeling done by FAA
• Measure the progression of flammability in the
  CWT of a typical commercial transport airplane

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OBIGGS - System Architecture

• 400 deg F bleed air enters electrically
  controlled operated Shut-off Valve on OBIGGS
  Control Box
• Air goes through heat exchanger by a cooling air
  throttling valve to control temperature manually
  using a ASM air input temperature sensor
• Some bleed air can bypass the heat exchanger if
  selected
• Conditioned air passes through dust/oil
  contaminant filter
• Air enters ASM and has OEA separated and dumped
  overboard

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OBIGGS - System Architecture (contd)

• NEA passes through high flow shut-off valve
  (Parker Box operator) and High/Low flow metering
  valves
• System controlled by control box in cabin that is
  connected to system with cable routed through
  wheel well
• Turns system on/off
• Select heat exchanger bypass on/off
• Select fan on/off
• Select high/low flow mode
• ASM input air temperature readout

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Assembled FAA OBIGGs Drawing
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OBIGGS - System Installation

• System installed in aft, right side fairing area
  (empty pack bay)
• System is mostly assembled before installation in
  the aircraft
• Total Weight 165 lbs
• System attaches to fairing structure at six
  locations with specially design mounting brackets
• Brackets designed by Shaw for canceled FAA joint
  flight test with Boeing
• 4 main brackets pick up existing fastener holes
  but two secondary brackets need to have holes
  drilled in stringer
• System wired to control box in cabin via a cable
  which attaches to the system 41-pin connector
• Powers/controls system components

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OBIGGS - System Installation (contd)

• System interfaces with bleed system via a main
  bleed duct manifold in that area
• 4-foot segment from SCA is removed and FAA
  segment installed
• Needs to align precisely with system bleed air
  input fitting
• System cooling air passes in a scoop and out the
  outflow box
• Two FAA panels with these parts already mated
  with aircraft

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Top View of System Installed
Inboard Aircraft Structure
Outboard Aircraft Structure
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Simplified OBIGG System Installation
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Empty Pack Bay Before/After System Installation
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OBIGGS - Deposit System

• Install deposit T and dual isolation valves
  allows for improved functionality of testing
  (counter-wire valves)
• Install a T in system NEA deposit
• 1 side of T goes to outflow box via a normally
  closed isolation valve
• Other side of T goes to flow meter, check
  valve, and a second normally open isolation valve
• Install AN bulkhead fitting in replaced pack bay
  canted bulkhead panel
• Route NEA from check valve to fitting with
  flexible hose

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Deposit System Overview
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NEA Deposit T
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Flow Meter/Deposit Installation
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NEA Diversion Valve Installation
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OBIGGS - Deposit System (contd)

• To deposit NEA in tank without permanent
  modification replaced purge door with
  instrumentation panel that passes the NEA,
  thermocouples, and gas samples (not FAS) into the
  tank from the wheel well adjacent to the pack bay
• NEA fitting is 1 SwageLok Bulkhead Fitting
• NEA routed to deposit nozzle mounted in the top
  of tank in Bay 6 (aft, right bay) via a 1-inch
  flexible line
• nozzle mounted in bracket attached to aircraft
  stiffener bracket between strings at top of tank
• Also Blocked Half Vent System

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Install Instrumentation Port
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Existing Stringer/Stiffener/Bracket Assembly
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Install NEA Deposit Nozzle and Associate Hardware
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Install Vent Blocking Plates
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Instrumentation and Data Acquisition

• Various thermocouples and pressure transducers
  used
• Evaluate system performance
• Measure tank flammability parameters
• OBIGGS system flow meter and 2-channel oxygen
  analyzer for NEA and OEA analysis
• Onboard Oxygen Analysis System (OBOAS) most
  critical measurements
• 8-channel system analyzes 8 locations in tank
• Flammability Analysis System (FAS) will measure
  progression of CWT flammability in flight
• 1 location in forward section of tank

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CWT Instrumentation

• Installation Instrumentation in the CWT of the
  NASA SCA
• Install Instrumentation Panel in Place of Purge
  Door
• Route and Mount Thermocouples
• Install Sample Port Float Valve Assembly and
  Route Lines as well as sample return lines
• Sub-Contractor (FFC) supported FAA installation
• Highly experienced in this type of work
• Statement of Work gives more details

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Route and Mount Thermocouples
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Install Sample Port Float Valve Assembly
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Instrumentation - Additional Thermocouples

• Use 16th Inch SS Sheath T-Type Thermocouple
  Probes
• Install one in each used pack bay and one in the
  OBIGGS pack bay
• Install 4 in the area of the bleed air connection
• Monitor for Bleed Air Leaks
• System has 6 thermocouples installed
• Thermocouple in cabin
• Thermocouples in measurement systems (OBOAS/FAS)

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Instrumentation - Pressure Transducers

• Measure Absolute Pressure at 4 locations on
  OBIGGS and measure static pressure in pack bay
• Potential to add 1 to bleed manifold if possible
• Purchase off-the-shelf lab pressure transducers
• Sensotec TJE Precision, Absolute series
• Run on 28 VDC, 12 VDC nominal bridge voltage,
  internally regulated
• 0-5 VDC output
• Mount transducers on panel in cabin
• Run 5 sense lines to pack bay

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Thermocouple Probe and Pressure Transducer
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Instrumentation - NEA Flow Meter

• Engineered Specifically for The FAA OBIGGS
• Designed from Existing Commercial and Military
  Assemblies by FCI
• Flight worthy instrumentation (No TSO)
• Uses vortex shedding heat release principal
• Also measures absolute temperature and pressure
  of flow
• 1 diameter flow tube integrates with existing
  deposit system on pallet

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Flow Meter
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System Instrumentation Diagram
Spare O2
Temperature
Static Pressure
Static Pressure
Temperature
NEA O2
Static Pressure
Temperature
OEA O2
Temperature
Static Pressure
Temperature
Temperature (FAA Reader)
Penetration Hole
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Instrumentation - OBOAS

• Two 4-Channel Systems Measure Oxygen
  Concentration Continuous at 8 Different Fuel Tank
  Locations
• Large diaphragm pump draws sample
• Actively controls sample inlet and outlet
  pressure.
• Flow through sensor design
• Fluid traps, Ejector/Evacuator, Flame Suppressors
  for Safety
• Mounts in standard 19 flight test half rack
  including sample system (OBUSS) contained in
  large, purged box

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OBOAS Block Diagram
Fuel Tank Vapor Fuel Tank Liquid Pressurized
Air Electrical Power Electronic Signals
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OBOAS Mounted in FAA AMCO Racks
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Instrumentation - FAS

• System uses a Non-Dispersive Infrared Analyzer
  (NDIR) to measure fuel tank flammability in the
  form of total hydrocarbons (THC)
• Sample stream must be heated at all points
  leading to the NDIR to prevent condensation of
  fuel vapors
• This is achieved in part via three heated hoses
• Installs in a rack and pallet for flight test

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Cabin Instrumentation/Rack Diagram
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Instrumentation - Power Distribution

• Power Distributed to the Various Equipment from
  Utility Rack at ST. 990
• 3-Phase 115 VAC 400Hz to Each OBOAS (13 amps/leg)
• 20 Amps of 115 VAC 60 Hz to FAS
• 5 Amps of 115 VAC 60 Hz to DAS and Computer
• OBIGGS takes 5 Amps 28 VDC and 3-Phase 115 VAC,
  400Hz (5 Amps/ Leg)
• Each OBOAS converter is tied to a switching unit
  that allows for power to be distributed between
  racks and to the OBIGGS O2 analyzer

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Power Distribution Diagram
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Data Acquisition System

• IOtech Ethernet Based Daqbook
• 16-bit 200 kHz A/D Converter
• Daisy chains slave units with 3-boards each
• Expandable up to 256 channels
• Specified approximately 78 channels of data
• CWT / OBOAS/ FAS - 48 channels
• System Instrumentation - 15 channels
• Misc. Temperatures - 9 channels
• Aircraft Parameters - 2 channels

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Data Acquisition System
Daqbook / 2000E
DBK60 Expansion
Data
Data
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Status

• CWT installation approved and completed
• OBIGGs, OBOAS, FAS, instrumentation/racks, DAS
  installation approved
• One sticking point
• OBOAS modified from Airbus testing and FAS
  completed
• Additional parts purchased
• NEA deposit completed,
• Instrumentation racks built up
• Preparing to ship all equipment for installation