# Presentation: 845312

## Louise C. Speitel
Fire Safety Branch ATO-P, AAR-440FAA W.J. Hughes Technical Center
Atlantic City International Airport, NJ  08405  USA

- Fire Safety Branch ATO-P, AAR-440FAA W.J. Hughes Technical Center
- Atlantic City International Airport, NJ  08405  USA

**Handheld Extinguisher Draft Advisory Circular Review**

- Aircraft Systems Fire Protection Working Group Meeting Atlantic City, New Jersey
- November 1 - 2, 2005

## OUTLINE OF TALK

-   Purpose of the handheld advisory circular (AC)
-   FAR requirements for hand-held extinguishers
-   Minimum performance standard (MPS) for transport category aircraft
-   Approach
-   Fire Fighting Guidance
-   Toxicity: decomposition products, agent, low oxygen hypoxia
-   Ventilation selector graphs
-   AC language for halocarbon fire extinguishers

## PURPOSE OF ADVISORY CIRCULAR

-   Provide safety guidance for halon replacement agents.
-  Effectiveness in fighting onboard fires.
-  Toxicity
-  Provides updated general information.
-   This AC is not a regulation.
-   Applies to aircraft and rotorcraft.
-   Requires adherence to outside documents:
-  ASTM specifications
-  MPS for hand fire extinguisher for transport category aircraft** **
-  CFR Title 40: Protection of the Environment, Part 82- Protection of Stratospheric Ozone, Subpart G, Significant New Alternatives Program and Subpart H- Halon Emissions Program.
-  Letter from the FAA Administrator

**PURPOSE OF ADVISORY CIRCULAR**

## PURPOSE OF ADVISORY CIRCULAR: Safety

*“**Provide methods for showing compliance with the hand fire extinguisher provisions in parts 21, 25, 29, 91, 121, 125, 127 and 135 of the Federal Aviation Regulations (FAR 14)”.   (Other avenues exist for showing compliance.)*

-    21      Certification procedures for products and parts
-    25	Airworthiness standards - Transport category airplanes
-    29	Airworthiness standards - Transport category rotorcraft
-    91	General operating and flight rules
-  121	Operating requirements - Domestic, flag and supplemental operations
-  125	Certification & operations- Airplanes having a seating capacity of 20 or more passengers or a maximum payload capacity of 6000 pounds or more
-  127	Certification and Operations of Scheduled Air Carriers with Helicopters ?
-  135	Air Taxi Operators and commercial operators.

##   Specifies the minimum number of Halon 1211 or equivalent extinguishers for various size aircraft. 

-   Specifies the minimum number of Halon 1211 or equivalent extinguishers for various size aircraft.
-   Specifies the location and distribution of extinguishers on an aircraft.
-   Each extinguisher must be approved.
-   Each extinguisher intended for use in a personnel compartment must be designed to minimize the hazard of toxic gas concentration.
-   The type and quantity of extinguishing agent, if other than Halon 1211, must be appropriate for the kinds of fires likely to occur.
-   The FAR does not give extinguisher ratings. This is done in the AC.

## THE MINIMUM PERFORMANCE STANDARD  (MPS) 

**FOR HAND-HELD EXTINGUISHERS**

-   Provides requirements for equivalency to Halon 1211 5 B:C extinguishers to satisfy Federal Aviation Regulations citing “Halon 1211 or equivalent”:
-   UL rated 5 B:C Halocarbon extinguishers that will be used in transport category aircraft must pass 2 tests identified in DOT/FAA/AR-01/37 _Development of a Minimum Performance Standard (MPS) for Hand-Held Fire Extinguishers as a Replacement for Halon 1211 on Civilian Transport Category Aircraft_.
-   Hidden Fire Test
-   Seat Fire/Toxic_i_ty Test
-   The MPS guarantees extinguishers to replace halon 1211 will have equal fire performance and an acceptable level of toxicity (for decomposition products of the agent). Guidance for agent toxicity can be found in the advisory circular.
-   The MPS states that a  permanent label be  affixed to the extinguisher identifying FAA approval for use on board commercial aircraft.

## THE LETTER FROM THE FAA  ADMINISTRATOR

-   UL listed 5B:C and equivalent EN3 listed hand extinguishers must meet the MPS for hand extinguishers.
-   A permanent label must be affixed to the extinguisher :
-  Label identifies FAA approval for UL listed 5B:C extinguishers for use onboard transport category aircraft based on meeting the MPS test requirements.
-  Label states the minimum safe volumes for that extinguisher at 8,000 , 14,000, 18,000 and 25,000 ft. pressure altitudes
-  Label should reference AC 20-42xx as containing safe-use guidance for that extinguisher onboard aircraft.
-  Label should not cover any data stamped on UL listed extinguishers, since this would invalidate the UL listing.

## RELATED SECTIONS

**FEDERAL AVIATION REGULATIONS (FARS)**

-   21.305     Certification procedures for products and parts
-   23.561      Normal, utility, acrobatic, and commuter category airplanes
-   25.561; 25.851    Transport category airplanes
-   27.561                 Normal category rotorcraft
-   29.561; 29.851; 29.853 (e) and (f)
-   91.193 (c)    ?
-   121.309 (c)
-   125.119 (b) and (c)** **
-   127.107 (c)  ?
-   135.155

## RELATED TITLES: CODE OF FEDERAL REGULATIONS (CFRs)

-   Title 40: Protection of the Environment
-   Title 46  Shipping
-   Title 49  Transportation
-          **OTHER RELATED INFORMATION (ACs and ADs)**
-    AC-120-80    In-Flight Fires
-    AC 20-42C   Hand Fire Extinguishers for Use in Aircraft
-    AD 93-07-15 (2)(i)   Airworthiness Directives:
-    Boeing Models 707, 727, 737, 747, and 757
-    McDonnell Douglas Models DC-8, DC-9, and DC-10

## COMBINED OR SEPARATE AC FOR

** ****HALON REPLACEMENTS?**

-   **ONE AC FOR ALL HANDHELD EXTINGUISHERS:**
-  The safe-use guidance for Halons would be changed to match the safe-use guidance for halon replacements.
-   New guidance for the halons would restrict Halon 1211 from being used in small aircraft.
-   Adoption would take years, or may never happen due to resistance from industry to lower the allowed weights of halon.

-   **SEPARATE  AC FOR HALON REPLACEMENTS: **
-   May be adapted relatively quickly. Halon replacements are available meeting UL and MPS requirements: Halotron I, HFC236fa, and HFC227ea. The Montreal Protocol and U.S. Clean Air Act require phase out of ozone depleting halons and transition to available alternatives.
-   Current A/C 20-42C for halons will be revised later.

## APPROACH 

-   The FAA Fire Safety Section is providing a draft Advisory Circular for halocarbon hand-held extinguishers.
-   The FAA’sTransport Airplane Directorate will edit the draft advisory circular.
-   Use science-based approach published in peer-reviewed literature and adapted in NFPA 2001 Standard for Clean Agent Extinguishing Systems.
-    Conservative
-    More accurate than approach used for halons** **
-   The safe-use guidance is based on an assessment of the relationship between halocarbons in the blood and any adverse toxicological or physiological effect.
-   Separate guidance provided to avoid low oxygen hypoxia.
-   Includes guidance for general aviation as well as transport category aircraft.
-  ** **Operators of non-transport category aircraft should become familiar with the information in this AC
-  This AC will be revised as new agents are introduced.

## EXTINGUISHER LISTINGS FOR HALONS

**   ****AC 20-42C:** **(Halons)**
-  A minimum UL listed 5 B:C sized extinguisher was recommended for Halon 1211 for all sized aircraft.
-  A minimum UL listed 2 B:C extinguisher was recommended for
- Halon 1301 for aircraft with a maximum certificated occupant capacity (MCOC) of 4 including the pilot.
** **Recommends a minimum 2A, 40B:C listing for accessible cargo compartments of combination passenger/cargo and cargo aircraft.
-    NFPA 408 allows a 2 B:C UL listed bottle of Halon 1211 in aircraft with a MCOC of 4.

## EXTINGUISHER LISTINGS FOR HALON REPACEMENT HALOCARBONS

- Aircraft Cabin:
-   Recommends a minimum 5B:C UL listing.
-   A permanent label is required, indicating  FAA approval for use on-board transport category aircraft, minimum safe volumes, and a reference to this circular.
-   For transport category aircraft, extinguishers with a minimum UL 5 B:C listing must meet the Minimum Performance Standard.
- Accessible Cargo Compartments: Passenger/Cargo & Cargo Aircraft:
-   Recommends a minimum extinguisher listing  of 2A:10B:C for compartments less than 200ft3
-   Compartments 200 ft3 and larger should meet the requirements of the FAA Airworthiness Directive  AD 93-07-15. This AD provides options to the use of hand extinguishers:
-  Conversion to meet Class C cargo compartment requirements
-  Use fire containment containers or covers.

## ACCESSIBLE CARGO COMPARTMENTS

**Cabin Safety Guidance:**
-  Cargo extinguishers should be available to fight cabin fires
-  Select a cargo extinguisher that meets the safe use guidance for the aircraft cabin
-  If no cargo extinguisher meets the safe use guidance for the aircraft cabin:
-  Consider installing a class C fire flooding suppression system in the cargo compartment or alternatives to handheld extinguishers that would provide effective fire protection.
-  Use the required UL listed extinguisher.
-  Select the least toxic agent of the required UL listing. Place a placard on or alongside the bottle stating: “Discharge of the entire contents of this size bottle into the occupied cabin area exceeds safe exposure limits. Use only the amount necessary to extinguish a fire”

## THROW RANGE

-   The MPS requires  a minimum throw range of 6-8 feet
-    A longer throw range of 10 feet or greater provides significant advantages in fighting fires in large aircraft cabins
-    A shorter throw range with a  lower velocity discharge is less likely to cause splashing &/ or splattering of the burning material. Consider a shorter throw range for very small aircraft
-   Select a range that would allow the firefighter to effectively fight fires likely to occur.

## FIXED NOZZLE/HOSE/ ADJUSTABLE WAND

-   For access to underseat, overhead and difficult to reach locations, it is recommended that extinguishers be equipped with a discharge hose or adjustable wand.
-   An extinguisher with a discharge hose or adjustable wand is more likely to result in the extinguisher being properly held during use.
-   Provides a means of directing a stream of agent to more inaccessible areas.
-   Fixed nozzle and adjustable wand allows one-handed use.

## USER PREFERENCE SURVEY

**USER PREFERENCE SURVEY**

*The toxicity issues for extinguishing agents in portable fire extinguishers is the most important concern of the airline industry as indicated in over 111 responses to the User Preference Survey conducted by the FAA sponsored IASFPWG.*

## TOXICITY CONSIDERATIONS

** ****Toxicity of the halocarbon itself**
-  Cardiotoxicity
- Anesthetic Effects
-  Guidelines in the proposed circular are stricter than UL 2129 “Halocarbon Clean Agent Fire Extinguishers”. Immediate egress is assumed in the UL 2129 standard.
**  ****Low oxygen hypoxia: Very small aircraft**
**  ****Toxicity of halocarbon** **decomposition products**
** **Guidelines set in the Minimum Performance Standard for Handheld Extinguishers

## APPROACH FOR SAFE EXPOSURES

-   Safe human exposure limits, up to 5 minutes are derived using a Physiologically-based Pharmacokinetic (PBPK) modeling of measured agent levels in blood .
-   Assume 70F (21.1C) cabin temperature, perfect mixing, and the following P altitudes:
-   8,000 ft-  Pressurized Aircraft .
-  14,000 ft- Nonpresurized aircraft with no supplemental oxygen.
-  18,000 ft- Nonpressuized aircraft with nasal cannula oxygen supply.
-  25,000 ft- Nonpressurized aircraft with oxygen masks (diluter demand).
-   Non-ventilated aircraft:
-  The allowed concentration would be based on the 5-minute PBPK safe human concentration if available. Otherwise,  the “No Observable Adverse Effect Level” (NOAEL) may be used.
-  Table provides maximum safe weight/volume ratios.
-   Ventilated aircraft: Selector graphs  will be included if PBPK data is available for that agent.

## AGENT TOXICITY :

**MAXIMUM SAFE CONCENTRATIONS**

- Total agent available from all required extinguishers should not be capable (assuming perfect mixing) of producing concentrations in the compartment by volume, at _**70oF (21.1oC)**__ __**when discharged at altitude**_   (for the appropriate pressure altitude), that exceeds the agent’s safe exposure guidelines. *(Note: Designing for altitude provides a large safety factor for ground use. No need for 120**o**F correction)*
**Nonventilated passenger or crew compartments:**
- PBPK derived 5 minute safe human exposure concentration, if known.
- If PBPK data is not available, the agent No Observable Adverse Effect Level **(NOAEL)**  is to be used. *(Note: UL 2129 allows use of a (sometimes higher) LOAEL Concentration)*
**  ****Ventilated Compartments:**
- Use ventilation selector graphs to obtain the maximum agent weight per cubic foot allowed in the cabin. Tables are based on PBPK modeling of theoretical concentration decay curves & perfect mixing. If tables are not available, follow concentration guidelines for nonventilated compartments.

## Solve equation or use  table:

- S = Specific volume of the agent at sea level:
-          At  70oF (21.1oC):  S= _____ ft3/lb
- A = Altitude correction factor for S:
-           8000 ft:       A= 760/ 564.59 = 1.346
-        14,000 ft:       A= 760/ 446.63 = 1.702
-        18,000 ft:       A= 760/ 397.77 = 1.911
-        25,000 ft:       A= 760/ 282.40 = 2.691
-  CAltitude is the maximum FAA allowed clean agent concentration (%)
-  *C**Altitude ** is not altitude dependent.*

***Solve equation or use  table:***

**MAXIMUM SAFE WEIGHT OF AGENT WITH                     NO VENTILATION**

- (W/V)Safe is based on ***all***** **hand extinguishers in the cabin

## AGENT TOXICITY: MINIMUM SAFE COMPARTMENT VOLUME    (NO VENTILATION, 70oF, 21.1oC) 

- For the following 5 B:C extinguishers, released at 70oF: (21.1oC)

| Agent       | Agent Weight (lbs) | Minimum Safe Volume (ft3) 1, 2 |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
|  |  | Sea Level
(For info only) | 8,000 ft P Altitude
(Pressurized Cabin) | 14,000 ft   P Altitude (Non-Pressurized Cabin) | 18,000 ft 3 P Altitude (Non- Pressurized) Nasal Cannula Oxygen Supply | 25,000 P altitude (Non-Pressurized)
Diluter-Demand Oxygen Mask
 |
| HCFC Blend B | 5.2 | 1337 | 1799 | 2276 | 2533 | 3586 |
| HFC-236fa | 4.75 | 85 | 115 | 145 | 163 | 220 |
| HFC-227ea | 5.75 | 108 | 146 | 184 | 2161 | 292 |
| Halon 12114
 | 2.5 | 556 | 749 | 947 | 1111 | 1497 |

***Use this table if air change time is unknown or exceeds 6 minutes***
***Multiply this number by the number of extinguishers in the aircraft***
***If nasal cannula oxygen on-board***
***(If the proposed halocarbon extinguisher AC was applied to the Halons)***

***nasal cannula***

## AGENT TOXICITY: MINIMUM SAFE COMPARTMENT WEIGHT/VOLUME    (NO VENTILATION, 70oF, 21.1oC) 

- For the following 5 B:C extinguishers, released at 70oF: (21.1oC)

| Agent | Minimum Safe W/V (pounds/ft3) 1,2 |  |  |  |  |
| --- | --- | --- | --- | --- | --- |
|  | Sea Level
(For info only) | 8,000 ft P Altitude
(Pressurized Cabin) | 14,000 ft   P Altitude (Non-Pressurized Cabin) | 18,000 ft 3  P Altitude (Non- Pressurized Cabin) Nasal Cannula Oxygen Supply | 25,000 ft P Altitude (Non- Pressurized Cabin) 
Diluter-Demand Oxygen Mask |
| HCFC Blend B | 0.00389 | 0.00289 | 0.00229 | 0.00195 | 0.00145 |
| HFC-236fa | 0.0579 | 0.0432 | 0.0342 | 0.0292 | 0.0216 |
| HFC-227ea | 0.0532 | 0.0394 | 0.0313 | 0.0266 | 0.0197 |
| Halon 12114 | 0.00450 | 0.0034 | 0.00264 | 0.00225 | 0.00167 |

***Use this table if air change time is unknown, or exceeds 6 minutes.***
***Multiply this number by 100 too get the min. safe wt for 100 ft******3 ******cabin.***
***If nasal cannula oxygen on-board***
***(If the proposed halocarbon extinguisher AC was applied to the Halon 1211)***

## AGENT TOXICITY: NO. OF 5BC BOTTLES ALLOWED

**(NO VENTILATION, 8000 FT ALTITUDE, ****70oF****)**

| Aircraft/ Helicopter | Vol (ft3) | Max No. Seats | Halon 1211 |  |  | HFC-236fa | Halotron 1 | HFC-227ea |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  |  | AC20-42C & UL1093 | AC20-42C
1 air-change /min | New AC | New AC | New AC | New AC |
| Cessna 152- | 77 | 2 | 0.3 | 0.4 | 0.1 | 0.6 | 0.04 | 0.5 |
| Cessna 210C | 140 | 6 | 0.5 | 0.7 | 0.2 | 1.2 | 0.08 | 1.0 |
| Cessna C421B | 217 | 10 | 0.7 | 1.1 | 0.3 | 1.9 | 0.1 | 1.5 |
| Sikorsky S76 | 204 | 14 | 0.7 | ___ | 0.2 | 1.8 | 0.1 | 1.4 |
| B727-100 | 5,333 | 131 | 17 | ___ | 6.4 | 47 | 3.1 | 37 |
| B767-200 | 11,265 | 255 | 36 | ___ | 14 | 98 | 6.5 | 77 |
| B 747 | 27,899 | 500 | 90 | ___ | 34 | 243 | 16 | 192 |

|  | Less than one 5 B:C extinguisher allowed |
| --- | --- |

## TOXICITY GUIDELINES FOR HANDHELDS

**(NO VENTILATION)**

| Agent  | AC 20-42C 
If Egress is possible within 1 minute | A/C20-42C
Otherwise,
Max Design Concentration | Max Safe Concentration (Constant Concentration) | Guidance for New A/Cs
(Altitude) |
| --- | --- | --- | --- | --- |
| Halon 1211 | 4%  at sea level
(basis for nomograms- used for ventilated compartments at 8,000 ft) | 2% at sea level | 2.8% for 15 sec
1.8% for 30 sec
1.3% for 1 min
1 % for 5 min | 1% for 5 min |
| Halon 1301 | 10%  at sea level
(basis for nomograms- used for ventilated compartments at 8,000 ft) | 5% at sea level | 10% for ~15 sec
6% for 5 min | 6% for 5 min |
| HCFC Blend B | N/A | N/A | Between 1% and 2% for 5 min | 1% for 5 min |
| HFC 236fa | N/A | N/A | 15% for 30 sec
12.5% for 5 min | 12.5% for 5 min |
| HFC 227ea | N/A | N/A | 12% for 30 sec
10.5% for 5 min | 10.5% for 5 min |

## KINETIC MODELING OF ARTERIAL HALON 1211 

**BLOOD CONCENTRATION (No Ventilation)**

**FAA allows up to 4% for 1 minute at sea level ****(7% at 14,000 ft)**** **
**FAA allows up to 8% for ventilated A/C at 8000 ft  ****(10% at 14,000 ft, 14% at 18,000 ft, 20% at 25,000 ft.)**

**Halon 1211 Concentrations Exceeding 1.0% are Not Safe**

**Halon 1211 Gas Concentrations**

## VENTILATION

-    ***WARNING***:  Small increase in concentration above the Maximum Safe 5 Minute Exposure Concentration results in a much shorter  time to effect:
- Safe human exposure to constant concentration:
- HFC 236fa : 12.5% for 5 min, 15% for 30 sec.
- HFC 227ea: 10.5% for 5 min, 12.0% for 30 sec.,
-   Development of  Ventilation Tables:
-   Based on total weight of agent on aircraft for ***all*** extinguishers.
-   Stratification of agents is a realistic expectation but is not included due to lack of acceptable methodology. Perfect mixing is assumed
-   Agent manufacturers may apply pharmacokinetic modeling  of blood concentration data to perfect mixing agent decay concentration curves.
-  Selector graphs for ventilated aircraft can be developed from that data.
-  Selector graphs provide the maximum agent weight per unit cabin volume allowed in an aircraft cabin for any known air change time.

## (assuming perfect mixing)

##    dB/dt = k1 C(t) - k2B(t)

**   ****dB/dt = k****1**** C(t) - k****2****B(t)**

- Blood
- B(t)

- Waste

**k****1**

**k****2**

- C(t)

**Lung**

## MODELING ARTERIAL BLOOD CONCENTRATIONS OF HALOCARBONS USING 1st ORDER KINETICS

## KINETIC MODELING OF ARTERIAL HALON 1211 BLOOD CONCENTRATION IN VENTILATED AIRCRAFT

**Critical Arterial Concentration**

**As ******** increases, arterial concentration (at t = ********) approaches 0.37x arterial conc with no air change) **

****** ****=1 minute**

****** ****=6 minutes**

****** ****= Air Change Time **

## KINETIC MODELING OF ARTERIAL HFC236fa BLOOD CONCENTRATION IN VENTILATED AIRCRAFT

**As ******** increases, arterial concentration (at t = ********) approaches 0.37x arterial conc with no air change) **

*k**1**= 27.73*
*k**2**= 3.924*

****** ****= Air Change Time**

## KINETIC MODELING OF ARTERIAL HFC237ea BLOOD CONCENTRATION IN VENTILATED AIRCRAFT

**As ******** increases, arterial concentration (at t = ********) approaches 0.37x arterial conc with no air change) **

****** ****= Air Change Time**

****** ****=6 minutes**

**Critical Arterial Concentration**

****** ****=0.5 minute**

****** ****=6 minutes**

*k**1**= 13.0*
*k**2**= 5.36*

## HFC236fa SELECTOR FOR

** ****VENTILATED COMPARTMENTS**

***Perfect mixing assumed***

**Add Curves for  18,000 ft. & 25, 000 ft. unpressurized aircraft**

## HFC236fa SELECTOR FOR

** ****VENTILATED COMPARTMENTS**

***Perfect mixing assumed***

- Ventilate immediately after fire extinguished. Increase ventilation to the highest possible rate.
- If Air change time is unknown or exceeds 6 minutes, use unventilated data (Prolonged exposure to these agents may be hazardous):
-  W/V = 0.0432 pounds/ft3 for pressurized cabins at 8,000 ft. P altitude
-  W/V = 0.0342** **pounds/ft3 for Nonpressurized Cabins at 14,000 ft.
-  W/V = 0.0292 pounds/ft3 for Nonpressurized Cabins at 18,000 ft.
-  W/V = 0.0216 pounds/ft3 for Nonpressurized Cabins at** **25,000 ft.
- Unpressurized aircraft should descend at* *the maximum safe rate to the minimum practicable altitude to avoid the life threatening hazards of hypoxia resulting from the agent displacing oxygen from the air and to minimize exposure to halogenated agents. This guidance should be followed regardless of ventilation rate.

## HFC227ea SELECTOR FOR 

**VENTILATED COMPARMENTS**

***Perfect mixing assumed***

**Add Curves for  18,000 ft. & 25, 000 ft. unpressurized aircraft**

## HFC227ea SELECTOR FOR 

**VENTILATED COMPARMENTS**

- Ventilate immediately after fire extinguished. Increase ventilation to the highest possible rate.
- If Air change time is unknown or exceeds 6 minutes, use unventilated data (Prolonged exposure to these agents may be hazardous):
-  W/V = 0.0394 pounds/ft3 for pressurized cabins
-  W/V = 0.0313 pounds/ft3 for nonpressurized cabins at 14,000 ft
** **W/V = 0.0266 pounds/ft3 for nonpressurized cabins at 18,000 ft
-  W/V  = 0.0197 pounds/ft3 for nonpressurized cabins at 25,000 ft.
- Unpressurized aircraft should descend at* *the maximum safe rate to the minimum practicable altitude to avoid the life threatening hazards of hypoxia resulting from the agent displacing oxygen from the air and to minimize exposure to halogenated agents. This guidance should be followed regardless of ventilation rate.

***Perfect mixing assumed***

## 1st ORDER KINETIC MODELING OF ARTERIAL 

**BLOOD CONCENTRATION HISTORIES**

-   Provides a ***simple mathematical solution***  to obtain data needed to develop perfect mixing ventilation tables which will provide maximum safe extinguishing agent weights for a range of compartment volumes and air change times.
-   Monte Carlo simulations of arterial blood concentration histories for 5 minute exposures to constant agent concentrations are used as input data for developing equations (95% confidence) for each extinguishing agent.
-   PBPK arterial blood data has been published for HFC 236fa and HFC 237fa which accounts for 95% (two standard deviations) of the simulated population having 5 minute arterial  blood concentrations below the target concentration.
-   Equations can be developed for each agent, which transform agent concentration histories to arterial blood concentration histories in ventilated spaces.
-   Demonstrated to work for predicting blood concentration histories for exposures to a constant concentration of agent.
-   Has been validated for predicting blood concentration histories for exposures to changing concentrations of agent.

## LOW OXYGEN HYPOXIA AT ALTITUDE: 

**Unpressurized Small Aircraft**

##  Provide safety guidance for halocarbon extinguishers.

-  Provide safety guidance for halocarbon extinguishers.
-  Recommends a minimum UL listed 5 B:C extinguisher for occupied spaces
-  The proposed A/C recommends adherence to the Minimum Performance Standard  for Handheld Extinguishers for occupied compartments on transport category aircraft.
-  Recommends throw ranges for various sized aircraft
-  Recommends a discharge hose or adjustable wand.
-  Provides guidance for minimizing risk of low oxygen hypoxia when agent is released at altitude.
-  States the maximum weight that ***all*** extinguishers should not exceed, based on agent toxicity, size of compartment, and maximum FAA-allowed altitude of the cabin.

##   May allow increased halocarbon clean agent concentrations in ventilated compartments: 

-   May allow increased** **halocarbon clean agent concentrations in ventilated compartments:
-  Selector graphs can be developed if PBPK data is available.
-  Selector graphs provide the maximum safe weight of agent based on safe concentration at altitude, compartment volume, time for an air change.
-  Provides updated safe handling guidelines based on adverse toxicological or cardiac sensitization events, PBPK modeling, and hypoxia considerations.
-  Operators of non-transport category aircraft should become familiar with the information in this A/C.
-    The proposed AC is subject to change/ rewrite by the FAA Aircraft Certification Office.

## WORKING GROUP PARTICIPANTS

** **Louise Speitel		FAA
-  Rich Mazzone		Boeing
-  Bradford Colton		American Pacific Corp
-  Howard Hammel		Dupont
-  Steve Happenny    	FAA
-  Paul Hinderliter		Dupont
-  Gary Jepson		Dupont
-  Bella Maranion		EPA
-  Reva Rubenstein		ICF Consulting
-  Robert Shaffstall		FAA
-  Arnold Angelici		FAA
-  Al Thornton		Great Lakes Chemical Co.
-  Mike Miller 		Kidde Aerospace
-  Mark Bathie		CASA, Australia

## Task Group Meeting

- Wed. Nov 2 at 1:30pm
*(Open to all)*

## http://www.fire.tc.faa.gov

- _[http://www.fire.tc.faa.gov](http://www.fire.tc.faa.gov/)_