Engine Nacelle Halon Replacement, FAA, WJ Hughes Technical Center

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Engine Nacelle Halon Replacement,FAA, WJ Hughes
Technical Center

• Point of Contact Doug Ingerson
• Department of Transportation
• Federal Aviation Administration
• WJ Hughes Technical Center
• Fire Safety Branch, AAR-440
• Bldg 205
• Atlantic City Int'l Airport, NJ 08405 USA
• tel [phone]
• fax [phone]
• email Douglas.A.Ingerson_at_faa.gov
• web page http//www.fire.tc.faa.gov/

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• Major Topics for Review
• brief overview
• revision to minimum performance standard for
  engine/apu (mpse)
• foundation test plans and results
• near term plans

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• BRIEF OVERVIEW
• April - July 2002, Testing
• Encountered difficulty with hot surface ignition
  (HSI) during initial MPSE tests
• Ran series of tests and observed HSI behavior -
  determined phenomena is unreliable
• Reviewed a sample of reported HSI behaviors
• Results indicated current version of the MPSE was
  faulted by HSI unreliability
• Ran 100 plus tests to find a way to circumvent
  HSI unreliability
• 23 24 July 2002, Task Group Meeting
• Convened and discussed issues involving MPSE and
  HSI
• Agreed MPSE required revision
• Conceived method to track Halon 1301 suppression
  performance using HSI reliably
• Formulated rough revision of MPSE (revision 3)
• Planned foundation testing to resolve potentially
  complicating issues
• August 2002 - Present
• Produced a crude flowchart of MPSE revision 3
• Partially completed the foundation testing

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• REVISION OF THE MPSE
• Evaluating the Basis for the Agent Comparison in
  the MPSE
• MPSE process will have error in results due to
  environmental behaviors observed to date -
  conservatism is required, yet error must be
  minimized where possible
• Experienced/reported difficulty with reliable HSI
  behavior would lead to greater expected error in
  final results
• Equivalence method must represent the associated
  application in a reliable manner
• Equivalence method relies on the occurrence of
  HSI as it is a threat in this application
• Testing during
• April - June 2002 the continually operating
  electrodes (COE) or a tube array of particular
  geometry reliably reignited JP-8
• June - July 2002 primary ignition difficulty
  with low volatility fuel (oil) in the spray fire
  scenario - suspected impact on HSI behavior using
  the COE alone
• July - August 2002 a combination of the COE and
  the tube array provided reliable HSI behavior for
  any fuel type evaluated

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• REVISION OF THE MPSE
• The Significant Change to the MPSE
• Former version of the MPSE
• reliance upon the definition of a robust fire
• equivalence process required finding a minimum of
  3 robust fires
• the robust fire was a mixture of test conditions
  that would be extinguished by Halon 1301 for a
  portion of a fixed number of duplicate tests
  (80-90)
• a successful quantity of the replacement
  candidate was to repeat Halon 1301 behavior
  against the same conditions
• HSI in this geometry is an imprecise behavior and
  was buried in the robust fire
• Version 3 of the MPSE
• robust fire eliminated
• changed performance measure to Reignition Time
  Delay - the time between fire extinguishment and
  reignition which is based on a video review of
  the test
• Reignition Time Delay (RTD) is based on a
  minimum of 5 tests at like condition
• a successful quantity of a replacement candidate
  will be required to repeat or exceed the RTD for
  Halon 1301 at the same test conditions
• HSI is provided for with intentional secondary
  ignition sources

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• REVISION OF THE MPSE
• Items of Concern for MPSE revision 3
• Concerns are included for consideration in MPSE
  revision 3 to improve on the body of work to date
• Concerns are reasoned as impacts on the
  credibility of the final results
• compartment ventilation conditions
• agent storage, release, and distribution
• sufficient severity of the fire threat
• variation in the RTD must be observed and
  understood
• Concerns will be addressed with foundation
  testing and review of others work
• Retain portions of previous MPSE revision to
  minimize loss of time

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• REVISION OF THE MPSE
• Spray Fire Zone Configuration, MPSE revision 3

ELECTRODES
CORE
TUBE ARRAY
FUEL NOZZLES
2 TALL FLAME STABILIZATION RIB
sta 502
sta 510
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• REVISION OF THE MPSE
• Process Overview
• Parameter for comparing agent suppression
  performances is RTD not robust fire
• RTD is the duration of time between fire
  extinguishment and reignition
• RTD requires a test fixture which includes
  RELIABLE secondary ignition sources
• Primarily, a single RTD will represent a group
  of duplicate agent suppression tests
• Basis for success RTD Halon 1301 ? RTD
  Candidate replacement
• Testing will account for representative
• ventilation conditions
• agent storage and discharge considerations
• fuels types in a nacelle/APU
• fire scenarios
• Process will allow for rational test planning
• test against the most challenging condition(s)
• run verification tests against conditions not
  explicitly evaluated
• attempting to separate fire suppression and agent
  distribution performances

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• FOUNDATION TESTING
• Test Results - Purpose and General Comments
• Testing to
• answer questions conceived during initial
  discussions of MPSE revision 3
• provide data to observe behaviors and uncover
  issues not initially recognized
• Focused on previously stated concerns
• List of issues to be addressed by this testing
• verify the fire threats are sufficiently severe
• minimize/understand varying RTD behavior
• fuel type - observe/compare combustion behaviors
• agent discharge - consistent preburn or tube
  array temperature
• material changes in the tube array - determine
  its life span
• explore residual fire scenario - determine
• which fuel types can burn in this configuration
• the significance of HSI phenomena
• the effect of the orientation of the pan geometry
  on fire intensity

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• FOUNDATION TESTING
• Test Results (continued) - Varying RTD/Decision
  to Release Agent
• Run a series of spray fire tests and evaluate
  resulting RTDs
• Purposes
• determine if RTD variation can be better
  controlled by releasing the agent after
• a consistent preburn duration expires
• a consistent temperature in the tube array is
  attained
• use results to refine MPSE version 3
• Current test procedure relies on preburn duration
• Control of the test article changed for the
  trials involving tube array temperature
• Conditions
• air flow ? 2.2 lbm/s _at_ 100F
• JP-8 ? 0.25 gpm
• agent ? HFC-125 _at_ 5.2 lbm
• Fixed preburn duration ? 45 seconds
• Fixed tube array temperature ? 1440F

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• FOUNDATION TESTING
• Test Results (continued) - Varying RTD/Fuel-Spray
  Fire Intensity
• Ran spray fire tests and recorded temperature
  profiles
• Purposes
• observe fire behaviors
• compare energy signature for each fuel
  type/ventilation condition
• use data in refining MPSE revision 3
• Thermocouples spaced longitudinally in the flame
  path to provide representative picture of
  combustion behavior
• Each individual test condition was repeated 3
  times
• Fixture cooled down to near ambient condition
  between tests
• Test conditions
• fuels JP-8, oil (Mobil Jet Oil II), hydraulic
  fluid (Skydrol LD-4)
• fuel flow rates 0.25 gpm /- 0.03gpm
• ventilation conditions 2.2 lbm/s_at_100F 1.0
  lbm/s_at_300F
• no fire suppression agent released

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• FOUNDATION TESTING
• Test Results (continued) - Varying RTD/Fuel-Spray
  Fire Intensity
• Created averaged temperature profile from data
  for each set of 3 tests
• 8 thermocouples, sta 453, 4 (102 mm) 8 (204
  mm) above core, 2_at_0130, 0430, 0730, 1030
• 1 thermocouple buried in tube array,
  approximately sta 510 (515), 1200
• 1 thermocouple mounted on door exterior, sta 514,
  1130
• 2 thermocouples, sta 518, 4 8 above core,
  1200
• 4 thermocouples, sta 532, 4 8 above core,
  2_at_0100, 1100
• 6 thermocouples, sta 551 upper, 4 8 above
  core, 2_at_0130, 1030, 1200
• Calculated a relative heat production reference
  to compare combustion intensity
• calculated areas under the averaged temperature
  traces from 30 to 80 seconds
• summed all areas for thermocouples affected by
  fire (stas 510, 514, 518, 532, 551)
• subtracted area for sta 453 thermocouples to
  remove heat present in air stream

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• FOUNDATION TESTING
• Test Results (continued) - Residual Fire
  Investigation/Fuel Ignition
• Ran pool fire tests and recorded temperature
  profiles
• Purposes
• determine which fuels can be ignited in the
  residual fire scenario
• use data to refine MPSE revision 3
• Fixture geometry
• master fuel pan in the simulator filled to make a
  water bath
• smaller stainless steel fuel pan located in the
  water bath
• Test conditions
• fuels JP-8, oil (Mobil Jet Oil II), hydraulic
  fluid (Skydrol LD-4)
• fuel quantity 0.47 gallon (1 deep puddle) in
  10.5 x 10.3 x 1.5 deep pan
• fuel temperature prior to test 150F (by
  thermocouple submerged in fuel)
• ignition exposure 10 - 30 seconds
  intermittently for 3 minutes
• ventilation conditions 2.2 lbm/s_at_100F 1.0
  lbm/s_at_300F
• no fire suppression agent released

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• FOUNDATION TESTING
• Test Results - Conclusions
• Fire intensity
• clean simulator cross section was an insufficient
  threat
• secondary ignition elements required to maintain
  sufficient threat
• Varying RTD
• no significant difference noted between releasing
  agent based on consistent preburn or tube array
  temperature
• fuel types have varying energy signatures -
  expect impact on RTD to be noticeable
• JP-8 worst case for 2.2 lbm/s air flow_at_100F
• oil selected as worst case for 1.0 lbm/s air
  flow_at_300F
• tube array has a life span of 10 fire tests
• variation in environmental conditions observed as
  a noticeable impact
• Residual fire scenario
• JP8 was the only fuel ignited - oil and hydraulic
  fluid were not
• remaining tests are incomplete

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• NEAR TERM PLANS
• Complete foundation testing
• Determine the impact/relevance of HSI on the
  residual fire scenario
• Determine the impact of altering the fuel surface
  geometry in the residual fire scenario on
  combustion intensity
• Ultimately, need to bench-mark Halon 1301 in
  this scenario in some manner
• Finalize MPSE revision 3
• Discuss/resolve issues
• incorporate results of foundation testing
  completed to date
• agent - storage/distribution criteria
• final process - need to methodically evaluate
  replacement candidates without excessive test
  counts
• Commit process to paper
• Complete Testing for the replacement candidates
  by Jun 2003