Chapter 1. General Information about this Advisory Circular (AC)
1. What is the Purpose of this Advisory Circular (AC)?
a. We provide guidance for fire-fighting effectiveness, selection, location and mounting of hand fire extinguishers.
b. We establish the halocarbons hydrochlorofluorocarbon (HCFC) Blend B, hydrofluorocarbon (HFC)-227ea, and HFC-236fa as FAA approved replacement agents to Halon 1211 and Halon 1301.
c. This AC recommends that you transition to using these new halocarbon clean agents in fire extinguishers kept onboard aircraft and rotorcraft. We explain how to gain certification for halocarbon clean agent extinguishers intended to replace Halon 1211 hand-held extinguishers.
d. This AC recommends that dry chemical, dry powder, and carbon dioxide hand extinguishers, in general, should not be used in aircraft.
e. We also explain how to gain Federal Aviation Administration (FAA) certification for replacement agent fire extinguishers, which you may use to comply with Title 14 of the Code of Federal Regulations (14 CFR) parts 23, 25, 29, 91, 121, 125, 127, and 135.
f. This AC establishes an FAA approved minimum performance standard (MPS) for halon replacement agents which includes a hidden fire test and a seat fire/toxicity test.
This AC recognizes that toxicity of halocarbon agents and their decomposition products is a concern and should be a consideration for extinguisher selection. However, given the variability of extinguishers, application, compartment sizes and air change times, establishing specific selection criteria is impractical. The toxicity hazard is a secondary concern to an unextinguished in-flight fire.
h. This AC provides new general guidance in the form of safe-use weight per unit volume (W/V) that may be useful in extinguisher selection, and establishes marking criteria for halocarbon extinguishers.
i. We show how to reduce the health and safety risk of exposure to halocarbon clean agents and how to use halocarbon clean agent fire extinguishers.
j. We offer updated guidance on the continued safe-use of Halon 1211, Halon 1301, and Halon 1211/1301 Halon blend extinguishers.
k. This AC is not mandatory and does not constitute a regulation. It is not intended to require you to do anything beyond what is specifically required by the regulations. In it, we describe an acceptable means, though not the only means, to gain certification for fire extinguishers kept onboard aircraft and rotorcraft. However, if you use the means described, you must follow it entirely.
2. Who is this AC for?
We wrote this AC for those responsible for selecting, approving, purchasing, and maintaining hand fire extinguishers. The guidance in this AC is also for manufacturers, installers, modifiers, owners, and operators of airplanes and rotorcraft.
b. This AC is a method of compliance for transport category aircraft. Operators of nontransport category airplanes or rotorcraft should become familiar with the information, precautions, and the safe-use guidance in this AC.
Existing halon handheld fire extinguisher installations are not affected by the updated guidance in this AC. The guidance in prior revisions of this AC applies to specific extinguisher installations on existing approved type design aircraft. These extinguishers remain suitable for continued use based on a history of safe use of halon extinguishers on aircraft. However, although not required for new installations and in-service aircraft where practical, we encourage owners and operators to consider using FAA approved halon replacement extinguishers.
3. What has Changed in this AC from the Previous AC?
Replacement halocarbon clean agents were developed in response to restrictions on the production of ozone-depleting halon fire extinguishing agents. The restrictions were introduced under the Clean Air Act Amendments of 1990 which implemented the Montreal Protocol signed September 16, 1987, as amended. In addition, the International Civil Aviation Organization is considering further mandated limits on halon use in aircraft.
b. Since 1994, Halon 1211 has not been produced in the U.S. By 2010, Halon 1211 will no longer be produced anywhere in the world. However, recycled Halon 1211 is available for new and existing fire extinguishers. Halocarbon clean agent extinguishers hydrochlorofluorocarbon HCFC Blend B and hydrofluorocarbons HFC-227ea, and HFC-236fa are now commercially available. These halocarbon hand fire extinguishers have been evaluated and found to be effective fire-fighting agents. If properly used, these agents are safe to human
c. Safe-use guidance is provided for Halon 1211 and Halon 1301 and blends of these agents. Safe-use concentrations of Halon 1211 are lower than in the previous AC, because the guidance in this AC is more conservative.
Does This AC Cancel Any Prior ACs? This AC cancels AC 20-42C, dated March 7, 1984.
5. Where Can I find This AC and Other FAA Publications? You can find this AC on the Regulatory and Guidance Library (RGL) website: http://rgl.faa gov/. See appendix 3 in this AC for additional information and related documentation.
Chapter 2. Gaining FAA Approval for Fire Extinguishers
1. How are Hand Fire Extinguishers Approved?
Federal Regulations for Hand Fire Extinguishers. Hand fire extinguishers are required under 14 CFR §§ 23.851, 25.851(a)(1), 29.851(a)(1), 29.853(e) & (f), 91.513(c),
119.25, 121.309(c), and 135.155. We approve hand fire extinguishers to be used on aircraft under the provisions of 14 CFR § 21.305(d). Accordingly, this AC is provided as one means acceptable to us for the approval of hand fire extinguishers, other than water solution extinguishers approved under TSO-C19.
Note: Although 14 CFR parts 91 and 125 don't require our approval of hand fire extinguishers, we consider the information in this AC acceptable for use by Part 91 and 125 operators.
b. Extinguishers Approved Under Industry Standards Organizations. We approve hand fire extinguishers for use in aircraft when they meet industry standards. Extinguishers approved in this manner should also meet the safe-use guidance provided in this AC. In addition, replacement agents must meet additional requirements specified in paragraph 2 below.
We accept hand fire extinguishers approved by:
(1) U.S. - Underwriters Laboratories, Inc. (U.S. - UL) according to U.S. - UL Standard 711, Rating and Fire Testing of Fire Extinguishers, and U.S. - UL construction and performance requirements for specific agent extinguishers with a U.S. - UL Listing mark (See paragraph 3c below.) or equivalent such as:
(2) Factory Mutual Research Corporation (FM) with listing mark, or
(3) The U.S. Coast Guard (USCG) with marking per 46 CPR § 162.028.
Minimum Rating. Your hand fire extinguisher should be rated per the requirements of U.S. - UL 711, dated December 17, 2004 or equivalent, as noted in paragraph 1b above. Hand extinguishers produced in the U.S. or those used on airplanes and/or rotorcraft operated within the U.S. should meet U.S. - UL fire rating standards.
(1) Large Aircraft. The required hand extinguishers should be listed and have a minimum U.S - UL 5B:C rating or the equivalent. Exception: See chapter 4, paragraph 5 of this AC for minimum extinguisher ratings for use in accessible cargo compartments.
(2) Small Airplanes or Rotorcraft. You may use an extinguisher with a minimum rating of U.S. - UL 2B:C or equivalent on aircraft with maximum compartment volumes of up to 200 R'.
How are Halon 1211 Replacement Extinguishers Approved? Hand extinguisher replacement agents, such as the halocarbon clean agents intended to replace the required 2½ pound U.S. - UL. SB:C Halon 1211 extinguishers, may be approved for use on aircraft if the agent complies with the tollowing requirements:
a. Replacement Agent Health and Environment Approval.
(1) Evaluate any halon replacement agent using the U.S. Environmental Protection Agency (EPA) Significant New Alternatives Policy (SNAP) program according to 40 CFR part 82, subpart G. This process characterizes the health and environmental risk of a proposed replacement agent.
The three halon replacement agents covered by this AC were evaluated under the SNAP program. Halocarbon clean agents HCFC-Blend B, HFC-227ea, and HFC-236fa are approved for environmental and toxicological acceptability.
b. Replacement Agent Hand Extinguisher MPS. Evaluate the replacement agent/extinguisher using the two fire tests specified in the MPS technical report cited in appendix 3 paragraph 7s. MPS testing of replacement agents should be coordinated with and approved by your local ACO with the support of FAATC. These fire tests ensure that the replacement agent extinguishers provide equivalent fire fighting performance to Halon 1211. Clean agent extinguishers designed to replace the required 2½ pound Halon 1211 extinguisher onboard aircraft should comply with the following MPS provisions:
Hidden Fire Test. The hidden fire test evaluates the "flooding" characteristics of the replacement agent against a hidden in-flight fire and determines the ability of a streaming agent to function as a flooding agent. This is a hardware-specific test and the extinguisher design affects its performance. Each required 5B:C extinguisher model should pass this test to be certified as a Halon 1211 replacement on aircraft.
Seat Fire/Toxicity Test. The seat fire test is a baseline test that evaluates the effectiveness of the replacement agent in fighting a flammable fluid seat fire scenario and the associated toxicity hazard of the decomposition products of that agent. This test measures the agent's ability to extinguish a triple-seat fire in an aircraft under in-flight conditions and ensures an acceptable level of toxicity for the thermal decomposition products of the replacement agent.
If a particular required 5B:C extinguisher model passes the seat fire/toxicity test, other models of extinguishers do not need to be tested, if the same agent is used.
Note 1: Select a replacement agent or halocarbon extinguisher for your aircraft compartment according to the fire rating per its U.S - UL listing, not the agent weight.
Note 2: The effectiveness of a hand fire extinguisher relies upon the training, expertise and capabilities of the crew member utilizing the device.
(3) HCFC-Blend B, HFC-227ea, and HFC 236fa have demonstrated to meet the MPS and are approved for use.
C. National Certification. U.S. - UL 2129, Halocarbon Clean Agent Fire Extinguishers, dated January 3, 2007 with a required rating of U.S. - UL 5B:C or equivalent per U.S. - UL 711 or equivalent (see paragraph 1b above).
Note: Use the FAA approval marking label, (see paragraph 2e below) and the U.S - UL numeric rating listing, not the agent weight to select extinguishers for an aircraft compartment.
d. Specifications for Approved Halocarbon Clean Agents to Replace Halon 1211.
For hand fire extinguishers employing halocarbon clean agents replacing Halon 1211, the following American Society of Testing and Materials (ASTM) specifications apply:
(1) HCFC Blend B must meet ASTM D 7122-05, Standard Specifications for HCFC Blend B;
(2) HFC-227ea must meet ASTM D 6064-03, Standard Specifications for HFC-227ea, 1,1,1,2,3,3,3-Heptaflouropropane (CF;CHFCFs);
(3) HFC-236fa must meet ASTM D 6541-05, Standard Specification for HFC-236а, 1,1,1,3,3,3-Hexafluoropropane (CFSCH 2CF 3); ot
(4) New Halon 1211 replacement agents must have and meet an applicable ASTM or equivalent specification.
(5) Fire extinguisher manufacturers are responsible for the validation of agent purity whether using new or recycled agent.
Marking. If you are a manufacturer, each of your models of U.S. - UL 5B:C Halon 1211 replacement extinguishers that have passed the test specified in paragraph 2b(1) and 2b(2) above should be permanently and legibly marked with the following:
(1) "Meets FAA approved MPS per DOT/FAA/AR-01/37"
(2) The name of the listing agency and rating according to U.S. - UL 711 or equivalent. U.S. - UL extinguishers must have the UL listing mark (include UL copyright logo) with the four required elements: UL in circle mark; word "listed;" product or company name;
and issue/serial number or control number.
f. New Technologies and Extinguishers Containing New Replacement Agents.
Nothing in this AC is intended to restrict new technologies or use of new replacement agents provided they meet the regulations and guidance prescribed in paragraph 2 above.
(1) New agents introduced after the effective date of this AC should comply with the provisions of paragraph 2a through 2e above.
(2) If the documentation needed in paragraph 2f(1) is not yet officially published for a particular halocarbon agent, use the NOAEL values approved under the SNAP program mentioned in paragraph 2a(1) above. They can be obtained from the SNAP Program Coordinator at the EPA Office of Air and Radiation or on the public docket for that office and used to determine safe-use W/Vs in the absence of published FAA safe-use guidance. Safe-use W/Vs may be calculated using EPA's NOAEL values following the methodology outlined in appendix 3 reference paragraph 7m of this AC.
(3) The FAA Technical Center (FAATC) intends to publish future guidance on handheld extinguishers. This guidance will include safe-use W/V for ventilated compartments using FAA approved fire extinguishers containing halon replacement agents introduced after the issuance of this AC.
3_ How are Halon Extinguishers Approved?
a. National Certification. Required halon hand-held fire extinguishers approved for use on aircraft should have a minimum rating of UL 5B:C. Halon 1301 and Halon 1211/1301 blends are also used. Halogenated fire extinguishers must comply with U.S. - UL 1093, Halogenated Agent Fire Extinguishers, or equivalent, for Halon 1211, Halon 1301 and Halon 1211/1301 blends per U.S. - UL 711 or equivalent (see paragraph 1b above). It should be noted that on March 12, 2009, UL announced the withdrawal of US - UL 1093 and the continuance of existing certifications to the withdrawn US - UL 1093. UL will no longer accept the submittal of new or revised products, but all current compliant products covered under US - UL 1093 will continue to be authorized to bear the classification mark of Underwriters Laboratories Inc. until October 1, 2014.
b. Specifications for Approved Halon Agents. For hand fire extinguishers that still employ halogenated agents, only Halon 1211, Halon 1301, or blends of the two have been previously approved and used aboard aircraft. The following specifications cover the requirements for halogenated agents:
(1) Halon 1211 should meet the requirements of ASTM D7673-10, Standard Specification for Halon 1211-Bromochlorodifluoromethane (CF¿CIBr)), or ISO 7201-1:1989, Fire protection -- Fire extinguishing media - Halogenated Hydrocarbons - Part 1:
Specifications for Halon 1211 and Halon 1301.
(2) Halon 1301 should meet the requirements of ASTM D5632-08, Standard Specification for Halon 1301-Bromotrifluoromethane (CF Br)), or ISO 7201-1:1989.
(3) Hand fire extinguishers with halon agents may continue to be used on aircraft as long as recycled halon of proven acceptable quality is available. Recycled agents are still available for purchase, but the duration of their availability is unknown. Therefore, we encourage operators to consider replacing halon extinguishers after discharge with approved halon replacement extinguishers.
(4) An EPA exemption allows the production of halon blends from recycled halon for aircraft use. There are strict conditions to this exemption.
(5) Fire extinguisher manufacturers are responsible for the validation of agent purity whether using new or recycled agent.
Marking. If you are a manufacturer, mark your halon extinguishers permanently and legibly with the name of the listing agency and rating according to U.S. - UL 711 or equivalent.
U.S. - UL extinguishers must have the UL listing mark (include UL copyright logo) with the four required elements: UL in circle mark; word "listed;" product or company name; and issue/serial number or control number. FM extinguishers must have the FM listing mark. And, USCG extinguishers must have the "USCG approval 162.028/XX" marking.
Chapter 3. Selecting the Correct Hand Fire Extinguisher
1. What are the Different Types of Fires?
Classes of Fires. To properly select an appropriate hand fire extinguisher for use in an aircraft, you should consider the following classes of fires that are likely to occur onboard your aircraft, as defined in the appendix 3, paragraph 1 la of this AC.
(1) Class A. Fires involving ordinary combustible materials, such as wood, cloth, paper, rubber, and plastics.
(2) Class B. Fires involving flammable liquids, petroleum oils, greases, tars, oil base paints, lacquers, solvents, alcohols, and flammable gases.
(3) Class C. Fires involving energized electrical equipment where the use of an extinguishing media that is electrically nonconductive is important.
(4) Class D. Fires involving combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and potassium.
Lithium Battery Fires. Do not treat a fire involving a small number of lithium batteries as a Class D fire. We consider a small number of rechargeable lithium batteries as what would be found in portable electronic devices (PED) e.g. laptop computers, cell phones, pagers, audio/video/data recording or playback devices, messaging devices, personal digital assistants (PDAs), and two-way radios. See chapter 4 paragraph 1f of this AC on fire fighting training for further information.
2. What do the Numeral Ratings Mean? The labeling on fire extinguishers consists of numerals and letters used in combination to describe the extinguishers relative effectiveness on a specified Class/type(s) of fire(s).
Numerals are used with identifying letters for extinguishers labeled for Class A and Class B fires. The "numeral," which precedes the letter, indicates the relative extinguishing effectiveness of the device on a given size fire. This is dependent on the agent, the capacity of the device, discharge times, and design features. For example, an extinguisher rated as U.S. - UL 4A should extinguish about twice as much Class A fire as a U.S. - UL 2A rated extinguisher.
Numeral ratings are not used for extinguishers labeled for Class CorD fires. Extinguishers that are effective on more than one class of fires have multiple "numeral-letter" and "letter" classifications and ratings; for example, U.S. - UL 5B:C.
b. Additional Rating Guidelines for Halocarbon Extinguishers. For occupied spaces on transport category aircraft, extinguishers employing halocarbon clean agents, replacing required Halon 1211 extinguishers, should have a minimum U.S. - UL 5B:C or an equivalent rating. Halocarbon extinguishers are most effective on Class B and C fires. Extinguishers with greater capacity are also rated for Class A fires. Extinguishers with a 2B:C or 5B:C U.S. - UL rating, although not rated for use on Class A fires, have been shown to be effective in extinguishing surface Class A fires.
3. What Extinguishing Agents are Appropriate for the Different Types of Fires? The following extinguishing agents are appropriate for use on the types of fires specified in paragraph la above:
a. Water. Class A type fires are best controlled with water by cooling the material below its ignition temperature and soaking the material to prevent re-ignition.
b. Carbon Dioxide. Class B or C fires are effectively controlled by carbon dioxide as a blanketing agent.
Note: Carbon dioxide is not recommended for hand-held extinguishers for internal aircraft use.
Dry Chemicals. Class A, B, or C fires are best controlled by dry chemicals. The only "all purpose" (Class A, B, C rating) dry chemical powder extinguishers contain monoammonium phosphate. All other dry chemical powders have a Class B, C U.S - UL fire rating only.
Note 1: In general, dry chemicals are not recommended for hand extinguishers for internal aircraft use, due to the potential for corrosion damage to electronic equipment, the possibility of visual obscuration if the agent were discharged into the flight deck area, and the cleanup problems from their use.
Note 2: When approving a non-gaseous agent for installation on aircraft, evaluate the contamination impact to the structure, wiring and surrounding systems, and consider potential mixing of the agent residue with water. Using such extinguishers may require specific maintenance procedures addressing cleanup.
d. Halons. Class A, B, or C fires are appropriately controlled with halons. However, do not use halons on a class D fire. Halon agents may react vigorously with the burning metal.
Note: While halons are still in service and are appropriate agents for these classes of fires, the production of these ozone depleting agents has been restricted. Although not required, consider replacing halon extinguishers with halon replacement extinguishers when discharged.
Halocarbon Clean Agents. (Halons are a subcategory of halocarbons.) Class A, B, or C fires are appropriately controlled with the use of halocarbon clean agents. Never discharge halocarbon clean agents or water on a Class D (burning metal) fire. Halocarbon agents may react vigorously with the burning metal.
f. Specialized Dry Powder. Class D fires are best controlled by dry powder. Follow the recommendations of the extinguisher manufacturer because of the possible chemical reaction between the burning metal and the extinguishing agent.
Note 1: Specialized dry powder is not recommended for hand extinguishers for internal aircraft use.
Note 2: Fires involving a small number of Lithium primary batteries (containing molten Lithium) should not be treated as class D fires and specialized dry powder should not be used. See chapter 4, paragraph 1f of this AC for a discussion of appropriate extinguishing agents for Lithium battery fires.
4. What Extinguishing Agents are Compatible with Aircraft Materials?
Corrosion by Extinguishing Agents. Halocarbon clean agents are not corrosive, but review the material compatibility properties for acceptability to aircraft materials. Water itself is not corrosive, but may be rendered corrosive by the addition of antifreeze solutions. Specialized dry powder and monammonium phosphate dry chemical are corrosive to most sensitive electronic components and instruments.
b. Material Compatibility. Halocarbon clean agents can be used in numerous aircraft applications and it is important to review the materials of construction for compatibility when designing new equipment, retrofitting existing equipment, or preparing storage and handling equipment to incorporate halocarbon clean agents. Materials that should be considered include metals, elastomers, and plastics. Halocarbon clean agents or water should never be discharged on Class D (burning metal) fires. These agents may react vigorously with the burning metal.
See paragraph Ib above for the exception: Lithium battery fires involving carry-on appliances.
c. Corrosivity of Decomposition Products. The thermal decomposition products of halocarbon extinguishing agents are corrosive, particularly the acid halides: HF, HCI and HBr.
The decomposition products of burning aircraft materials are also corrosive. Yet decomposition products are minimized by quickly extinguishing the fire. Acid halide production is also based on the agent used and the size of the fire.
What are the Operating Temperature Tolerances?
Halocarbon clean agent extinguishers should operate properly after being conditioned at -40°F (-40°C) or -65°F (-54°C) as applicable and 120°F (49°C) for 16 hours as specified in U.S. - UL 2129 or U.S. - UL 1093, as applicable. Water extinguishers should be protected to -40°F (-40°C) by adding antifreeze and stipulated on the extinguisher nameplate.
Cold operation may require additional consideration in the selection of an extinguisher. This is particularly true for general aviation aircraft in extremely cold climates.
The hidden fire extinguishment tests in the MPS were conducted on halocarbon extinguishers equilibrated to 70°F. More agent, a lower boiling point agent, or an extinguisher design change, may be needed to extinguish hidden fires. Testing may be needed to select an appropriate extinguisher. The boiling points of the halocarbons (at 1 atmosphere) listed in this AC are:
(1) HCFC Blend B = 80.6°F (27.0°C),
(2) HFC-227ea 1.9°F (-16.4°C),
(3) HFC-236fa = 29.5°F (-1.4°C),
(4) Halon 1211 = 26.0°F (-3.4°C), and
(5) Halon 1301 = -72.0°F (-57.8°C).
6. General Guidelines for Hand Fire Extinguishers.
a. Consider the effects of agent toxicity, aircraft ventilation, agent stratification and hypoxia when selecting and sizing the necessary fire extinguisher for your specific application.
Chapter 4 of this AC provides more details.
Provide the required minimum number of hand held extinguishers. See chapter 5, paragraph 4 of this AC. All extinguishers must have the proper U.S. - UL rating, even in spaces where the safe use guidelines, as outlined in chapter 4 paragraphs 2, 4, 5, and 6 of this AC, are exceeded. The failure to extinguish a fire has catastrophic consequences for all aircraft occupants. Agent toxicity should be considered secondary to the immediate need to extinguish the fire.
Follow the safe-use guidance recommendations in chapter 4 of this AC for selecting extinguishers for your aircraft compartments to, "...minimize the hazard of toxic gas concentration...", mentioned in 14 CFR §§ 23.851(c)(2), 25.851(a)(8), and 29.851(a)(3).
d. Do not substitute two smaller extinguishers for one extinguisher of the proper UL rating, except as provided for accessible cargo compartments, as noted in chapter 4, paragraph 5c of this AC. The fire can grow quickly prior to the discharge of the second extinguisher.
e. Due to the relatively short discharge time of hand fire extinguishers: a U.S. - UL 5B and a U.S. - UL 1A: 10B:C rated extinguisher at approximately 8 seconds; and 13 seconds for a U.S. - UL 2A:10B:C extinguisher; training on the proper use of the fire extinguishers is very important.