# Presentation: 404107

## 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:			609-485-4945
- fax:		609-485-7074
- email:		Douglas.A.Ingerson@faa.gov
- web page:	_http://www.fire.tc.faa.gov/_

## Major Topics for Review :

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

## 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**

## 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**

## 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**

## 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**

## Slide 7

## REVISION OF THE MPSE

**Spray Fire Zone Configuration, MPSE revision 3**

- FUEL NOZZLES

- 2” TALL FLAME
- STABILIZATION
- RIB

- TUBE ARRAY

- CORE

- ELECTRODES

- sta 502

- sta 510

## Slide 9

## Slide 10

## Slide 11

## 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**

## Slide 13

## 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**

## Slide 15

## Slide 16

## 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 @ 100°F**
**JP-8 ******** 0.25 gpm**
**agent ******** HFC-125 @ 5.2 lbm**
**Fixed preburn duration ******** 45 seconds**
**Fixed tube array temperature ******** 1440°F**

## Slide 18

## 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@100°F & 1.0 lbm/s@300°F**
**no fire suppression agent released**

## 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@01:30, 04:30, 07:30, & 10:30**
**1 thermocouple buried in tube array, approximately sta 510 (“515”), 12:00**
**1 thermocouple mounted on door exterior, sta 514, 11:30**
**2 thermocouples, sta 518, 4” & 8” above core, 12:00**
**4 thermocouples, sta 532, 4” & 8” above core, 2@01:00, 11:00**
**6 thermocouples, sta 551 upper, 4” & 8” above core, 2@01:30, 10:30, 12:00**
**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 (sta’s 510, 514, 518, 532, 551)**
**subtracted area for sta 453 thermocouples to remove “heat” present in air stream**

## Slide 21

## Slide 22

## Slide 23

## Slide 24

## Slide 25

## Slide 26

## 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 : 150°F+ (by thermocouple submerged in fuel)**
**ignition exposure : 10 - 30 seconds intermittently for 3 minutes**
**ventilation conditions : 2.2 lbm/s@100°F & 1.0 lbm/s@300°F**
**no fire suppression agent released**

## Slide 28

## Slide 29

## 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@100°F**
**oil selected as worst case for 1.0 lbm/s air flow@300°F **
**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**

## 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**