# Presentation: 511241

## Engine Nacelle Halon Replacement

** **

- International Aircraft Systems Fire Protection Working Group

- Douglas Ingerson, Engineer
- Federal Aviation Administration
- WJ Hughes Technical Center
- Fire Safety Branch
- Atlantic City Int’l Airport, NJ USA
- tel : 609-485-4945
- email : Douglas.A.Ingerson@faa.gov

- 19Nov2008

## Presentation Overview

**Overview**
- the Minimum Performance Standard for Aircraft Engine Nacelle & Auxiliary Power Unit Compartments, revision 03 (MPSe rev03)
- Recent task group activity
- Recent test activity
**Discuss transitioning from MPSe rev03 to rev04**
**Conclusion**

## Overview, MPSe rev03

- Set the test configuration

- Establish halon 1301 performance

- Establish a mass equivalent condition for the replacement candidate equal to or better than halon 1301

- Capture the agent distribution for the mass equivalent

- Calculate the equivalent concentration from the agent distribution & associated mass equivalent condition

- continue

- iterate to find acceptable solution

- If a **spray fire** threat,
- perform fuel verification testing

- Complete these
- test configurations :
- 		HIGH air flow/JP8 spray fire
- 		HIGH air flow/JP8 pool fire
- 		LOW air flow/OIL spray fire
- 		LOW air flow/JP8 pool fire

- Select the largest equivalent concentration as the recommendation for certification

- NO

- YES

- Are 4 test configurations completed?

## Overview, Recent Task Group Activity

**Task group met, 2Nov2007 & 18Nov2008**
**Principle Outcomes, 2007**
- Remove halon 1301 use from MPSe
- Replace halon 1301 with a surrogate gas, HFC-125
- Consider other means to quantify fire extinguishing agents
**Principle Outcomes, 2008**
- updated verbally (information not available at press time)

## Overview, Recent Test Activity

**A Boeing/Kidde initiative was supported during 2006-2008 with sporadic FAATC testing**
**Worked with a solid-aerosol, fire extinguishing agent**
**Support stopped prior to completing MPSe rev03**

## Transitioning from rev03 to rev04Overview

**Identify what will be retained from MPSe rev03**
**Terminate halon 1301 usage**
- Use a surrogate
- Specifying the fire threats
**Address agent injection dependence**
- Background
- Change from determining the agent quantity to proof-testing some agent quantity
- Review how/where to quantify fire extinguishing agent

## Transitioning from rev03 to rev04(continued)

**What will be retained from MPSe rev03 ?**
- Test fixture geometry
- Ventilation constraints
- Fire threat constraints
- Spray & pool combustion behaviors
- Hot surface & electrical ignition sources
- Varied fuel types
- Fuel flow rate and pool geometry
- Fire extinguishing agent constraints
- Storage temperature
- Continued requirements to mitigate agent injection phenomena

## Transitioning from rev03 to rev04(continued)

**Terminate halon 1301 usage**
- Preliminary comments
- Benchmarking with a halon 1301 surrogate is an interim solution
- Eliminates halon 1301 usage
- Permits observing the global drift in the test environment
- HFCs will likely become regulated
- No other surrogate can readily be utilized
- limited experience; HFC-125, CF3I, & FK-5-1-12
- none as gas-like as halon 1301, except HFC-125
- Fire threat specification will occur

## Transitioning from rev03 to rev04(continued)

## Transitioning from rev03 to rev04(continued)

**Terminate halon 1301 usage (continued)**
- Halon 1301 surrogate pathway
- Surrogate is HFC-125
- Use surrogate as a benchmark for 1 of 4 test configurations
- Compare remaining configurations to historical halon 1301 performance
- Fire threat characterization pathway
- Work in parallel
- Will transition seamlessly from surrogate benchmark method
- Describe salient details within test process

## Transitioning from rev03 to rev04(continued)

**Address agent injection dependence**
- Background
- The internal energy of the fire extinguishing agent is playing a role in MPSe outcome
- The more recently evaluated chemicals have internal energies similar to the early halons, which are known to be more dependent upon their respective injection systems than is halon 1301
- The role of this dependence must be minimized in the MPSe process

## Transitioning from rev03 to rev04(continued)

## Transitioning from rev03 to rev04(continued)

**Address agent injection dependence (continued)**
- Change from determining the agent quantity to proof-testing some agent quantity
- The MPSe will become a proof-test
- Any entity moving forward some replacement candidate will identify the agent dosage (amount & residence time) prior to MPSe testing
- The lowest quantity of agent considered for MPSe testing will be a 30% increase above experimental cup-burner values, as described in NFPA 2001
- The bench-scale test procedure is based on liquid-fueled, diffusion flame combustion, thus similar to nacelle fires
- Flow field & agent concentration gradients are minimized, thus minimizing agent injection phenomena

## Transitioning from rev03 to rev04(continued)

**Address agent injection dependence (continued)**
- Review how/where to quantify fire extinguishing agent
- Regarding ALL MPSe testing to date
- Based on free-stream agent concentration measurements
- Halon 1301 performance was defined on a 12-point sampling volume
- Reported replacement outcomes are based on 2 points at the flame front
- Indications point to measuring in recirculation zones, not free-stream
- Recent literature indicates (NIST Special Pub 1069) :
- Values from a cup-burner assay are adequate predictors of agent quantity needed for flame extinction in aircraft engine nacelles
- These quantities must reside in the recirculation zones for some indeterminate duration
- However, HFC-125 Design Model (AFRL-VA-WP-TR-1999-3068) outcomes conflict with NIST Special Pub 1069

## Transitioning from rev03 to rev04(continued)

## MPSe rev04(h1301 surrogate)

- Set the test configuration

- If the test configuration requires establishing the singular surrogate performance, do so

- Demonstrate halon replacement dosage is equal to or better than (1) the surrogate or (2) historical halon 1301 performance

- continue

- iterate to find acceptable solution

- If a **spray fire** threat,
- perform fuel verification testing

- Establish the concentration profile (dosage) of the halon replacement candidate to be proof-tested for HIGH & LOW air flow conditions

- Complete these
- test configurations :
- 		HIGH air flow/JP8 spray fire
- 		HIGH air flow/JP8 pool fire
- 		LOW air flow/OIL spray fire
- 		LOW air flow/JP8 pool fire

- The agent dosage successfully completing the challenges is recommended for certification

- NO

- YES

- Are 4 test configurations completed?

## MPSe rev04(no h1301 surrogate)

- Set the test configuration

- continue

- iterate to find acceptable solution

- Establish the concentration profile (dosage) of the halon replacement candidate to be proof-tested for HIGH & LOW air flow conditions

- Complete these
- test configurations :
- 		HIGH air flow/JP8 spray fire
- 		HIGH air flow/JP8 pool fire
- 		LOW air flow/OIL spray fire
- 		LOW air flow/JP8 pool fire

- The agent dosage successfully completing the challenges is recommended for certification

- NO

- YES

- Are 4 test configurations completed?

- Demonstrate halon replacement dosage is equal to or better than the historical halon 1301 performance

- If a **spray fire** threat,
- perform fuel verification testing

## Conclusions

**Agent distribution is interfering with MPSe rev03**
**MPSe rev04 will :**
- not require halon 1301 use
- remain a salient, 4-condition, evaluation process
- require known fire extinction performance for a replacement candidate prior to full-scale testing
- be a proof-test
- start as a surrogate benchmark concept, then transition to a non-surrogate, fire-specified challenge
**Must review agent measurement to address agent injection dependence & relate historical work**

## End