5. How to Safely Use Halocarbon Extinguishers in Accessible Cargo Compartments.
a. Unsafe Concentrations of Extinguishing Agent. 14 CFR § 25.857 and § 29.855(d) require aircratt to be designed to prevent the harmful accumulation of smoke, flame, extinguishing agent and noxious gases from entering occupied areas. Airplane Flight Manual (AFM) fire fighting procedures should state that the crew member should close the Class B cargo compartment door after extinguishing a fire.
When to Use Portable Protective Breathing Equipment (PBE). Portable PBE should be worn before entering the cargo compartment and attempting to extinguish a fire, as outlined in 14 CFR § 25.1439. Note that AFM and/or Crew Operations Manual are required to have the appropriate procedure including calling out the use of portable PBE and other emergency equipment necessary to fight a fire.
Compartments Under 200 Cubic Feet. Halon replacement extinguishers should have a minimum fire rating classification of U.S. - UL 2A:10B:C for accessible Class B cargo compartments, combination passenger/cargo (combi) and cargo airplane/rotorcraft. The fire threat for accessible cargo compartments is primarily from Class A fires. Usually, one extinguisher with a U.S. - UL 2A: 10B:C rating is sufficient to fight most fires likely to occur.
(1) Multiple hand-held fire extinguishers may be shared to comply with the cabin and accessible Class B cargo compartment regulations, if they are located where a person fighting a fire in the compartment could quickly retrieve them and continue fighting the fire with minimal delay between the discharges. It must be demonstrated that the extinguishers, as installed, can extinguish 2A and 10B:C rated fires. The combined rating is to be determined by performing the UL 711 fire tests by discharging the extinguishers with a delay between the end of each extinguisher's discharge and the start of the discharge of the next extinguisher based on the location of each extinguisher and an assessment of factors such as:
(a) The manpower available to fight the fire. If two trained crew members are available to fight the fire, it may be possible to avoid a delay between discharges of the extinguishers.
(b) The time to recognize the completion of the discharge, to walk to the location of the next bottle, remove it from it's mounting bracket, pull the pin, return to the cargo compartment, position the extinguisher to continue to fight the fire and initiate discharge.
(2) The rating is based on UL 711 performance tests, not agent weight, as the agent weight is not sufficient to predict performance. Nozzle design, super pressurization and other factors affect performance. The UL fire tests can be preformed by the applicant or an approved test laboratory such as UL.
Note: The recommended extinguisher rating of 2A: 10B:C is lower than the 2A:40B:C rating in AC 20-42C. This is because the fire threat for accessible cargo compartments is primarily from Class A fires. The prior guidance in AC 20-42C was based on the need for at least a 2A rating for class A fires using a Halon 1211 extinguisher to extinguish a fire. Halon 1211 extinguishers that have a class A rating of 2A also have a 40B:C rating. It has been determined that a 10B:C rating is more then adequate for the type and size of class B and C fires likely to occur in a Class B cargo compartment.
Compartments Over 200 Cubic Feet. Accessible cargo compartments of 200 ft3 and larger, in combination passenger/cargo and cargo aircraft/rotorcraft, should comply with the requirements of the FAA Airworthiness Directive (AD) 93-07-15. This AD specifies acceptable forms of fire protection equipment and operational procedures. The options provided include converting the compartment to meet the requirements of a Class C cargo compartment, use of hand-held fire extinguishers, or the use of fire containment containers or covers, fire extinguishing systems and smoke or fire detectors.
(1) If you elect to use hand fire extinguishers provide the following:
(a) A minimum of three U.S. - UL listed Halon 1211 or its equivalent 2A: 10B:C hand held fire extinguishers (equivalent to the AD's requirement of 48 Ibs. of Halon 1211) readily available for use in the cargo compartment.
(b) At least two U.S. - UL 2A (2-1/2 gallon) listed water portable fire extinguishers, usually TSO C19 or its equivalent, adjacent to the cargo compartment entrance for use in the compartment.
(c) Protective garments stored adjacent to the cargo compartment entrance.
(d) Portable PBE with a minimum of 15 minutes of protective breathing, per 14 CFR § 25.1439(b)(5). This portable PBE should be TSO C116 approved or equivalent, and be stored adjacent to the cargo compartment entrance.
(2) If no extinguisher is available that meets the safe-use criteria for the aircraft/rotorcraft cabin, consider converting that cargo compartment to a class C compartment with a built-in fire suppression system, or any other technology that would provide effective fire protection. Restrict personnel from entering the cargo compartment for the duration of the flight.
How to Inspect and Maintain the Hand Fire Extinguisher for Continued Safe-Use.
Maintain and inspect hand fire extinguishers in accordance with the manufacturer's nameplate instructions. Follow the maintenance procedures, inspections and testing specified in the applicable NFPA and U.S. - UL standards.
a. Non-refillable, disposable fire extinguishers may have plastic discharge heads installed. Locate this type of fire extinguisher in a safe area to assure there will be no damage to the plastic discharge heads.
b. Non-refillable, disposable fire extinguishers are exempt from periodic hydrostatic testing. However, replace these extinguishers with a serviceable unit upon reaching:
(1) The service life where hydrostatic testing would normally be required for a similar extinguisher, or
(2) The service life guidelines established by the manufacturer if sooner.
c. Recommended procedures for the inspection, hydrostatic test and life limits of pressure cylinders are outlined in:
(1) Specification of cylinders is in 49 CFR, part 178, subpart C.
(2) Inspection and maintenance of cylinders is in 49 CFR, part 180, subpart B.
(3) Fire extinguishers are addressed in 49 CFR § 173.309 and in 29 CFR § 1910.157.
d. Manufacturers of fire extinguishers containing halon replacement agents approved for use on FAA certified aircraft should take immediate action through the appropriate channel(s) to have their retest requirements included in the aforementioned regulatory guidelines.
Chapter 5. Locating and Mounting Hand Fire Extinguishers Where to Locate and Mount Hand Fire Extinguishers in Passenger Compartments.
Install fire extinguishers in passenger compartments according to 14 CFR §§ 23.851, 25.851, and
29.853 and the following criteria:
a. Locate hand fire extinguishers adjacent to hazardous areas (for example, galleys, accessible baggage or cargo compartments, electrical equipment racks, etc.) to be protected.
b. If there are no defined hazardous areas, locate the hand fire extinguishers as follows:
() When one extinguisher is used, locate it at the flight attendant's station.
(2) When no flight attendant is required, locate the extinguisher at the passenger entrance door.
(3) When two or more extinguishers are used, locate one at each end of the passenger compartment and space the remainder uniformly within the cabin area.
C. Mount hand fire extinguishers for ready accessibility. It they are not visible in their mounted position, use a placard to indicate their location.
(1) Aircraft structure and mounting brackets are required to withstand the applicable inertia forces required in 14 CFR §§ 23.561, 25.561, 27.561, and 29.561, with the hand fire extinguisher installed. Replacement of halon extinguishers with halocarbon extinguishers will require an evaluation of the mounting system strength. The mounting structure may need to be strengthened. Halocarbon clean agent extinguishers of the same listing can be 2-3 times the weight of the halon extinguishers they are replacing.
(2) For large transport category aircraft, installation of an extinguisher should include vertical reach combined with horizontal (offset) reach to ensure ease of retrieval from overhead compartments. The vertical reach should not exceed 74.5 in. (189.23 cm) combined with an offset reach of 7.87 in. (20cm) to permit a 5 percentile female, 60.5 in. (153.67 cm.) tall to quickly access the extinguisher. Consideration should be allowed for assist steps (or seats) or other factors.
(3) Add the weight of the hand fire extinguisher and its mounting bracket to the aircraft empty weight and a compute a new empty weight center of gravity.
Consider the type of fire hazard (Class A, B, CorD) expected to be encountered when you select a hand fire extinguisher. If extinguishers intended for different classes of fire are grouped together, consider marking their intended use conspicuously via a placard or other means (near the extinguisher) to aid in the choice of the proper extinguisher at the time of the fire.
2. How to Locate and Mount Hand Fire Extinguishers in Flight Deck Compartments.
Consider using the following criteria if you install a fire extinguisher in the flight deck compartment:
a. Each hand fire extinguisher should be conveniently located, readily accessible, and it's location obvious.
b. Hand fire extinguishers should be mounted for easy release and removal. For aircraft designed for single pilot operation, the hand fire extinguisher should be located for release and removal by the pilot in the seated position.
(1) Secure the extinguisher(s) in mounting brackets) such that it requires a deliberate action to release the extinguisher from its primary restraint for removal from its mounting. Design the mounting bracket so that upon release from their primary restraint, the extinguisher remains in position until removed from its mounting by the user.
(2) Aircraft structure and extinguisher mounting brackets must be capable of withstanding the inertia forces specified in paragraph 1c above.
c. Fire extinguishers for the flight deck compartment should be able to extinguish Class B and C fires.
3. How to Locate and Mount Hand Fire Extinguishers in Small Single Engine and Multiengine Aircraft.
a. Locate hand fire extinguishers so that they are easily accessible to the flight crew and the passengers.
b. Do not allow hand fire extinguishers to lie loose on shelves, seat back pockets or seats. Properly mount the hand fire extinguisher to the airframe structure.
c. Aircraft structure and extinguisher mounting brackets should be capable of withstanding the inertia forces specified in paragraph 1c above.
4. How Many Hand Extinguishers Must I Install?
a. Transport Category Airplanes. 14 CFR §§ 25.851(a) and 121.309(c) requires a minimum number of hand extinguishers to be installed on transport category airplanes.
(1) The minimum number of hand fire extinguishers that must be conveniently located and evenly distributed in passenger compartments are as shown in Figure 2 below.
Figure 2. Minimum Number of Hand Fire Extinguishers Required for Transport Category Aircraft Passenger Compartments Passenger No. of Capacity Extinguishers 7 through 30 31 through 60 2 61 through 200 3 201 through 300 4 301 through 400 5 401 through 500 6 501 through 600 7 601 through 700 8
(2) At least one hand fire extinguisher must be conveniently located in the pilot compartment.
(3) At least one readily accessible hand fire extinguisher must be available for use in each Class A or Class B cargo or baggage compartment and in each Class E cargo or baggage compartment that is accessible to crewmembers in flight, per 14 CFR § 25.851(a)(3).
(4) At least one of the required fire extinguishers located in the passenger compartment of an airplane with a passenger capacity of at least 31 and not more than 60, and at least two of the fire extinguishers located in the passenger compartment of an airplane with a passenger capacity of 61 or more must contain Halon 1211, or equivalent, as the extinguishing agent.
(5) The quantity of extinguishing agent used in each extinguisher required by this section must be appropriate for the kinds of fires likely to occur where used.
b. Transport Category Rotorcraft. Title 14 CFR § 29.853 requires a minimum number of hand extinguishers to be installed in passenger compartments:
(1) See Figure 3 below for the minimum number of hand fire extinguishers that must be conveniently located in passenger compartments.
Figure 3. Minimum Number of Hand Fire Extinguishers Required for Transport Category Rotorcraft Passenger Compartments Passenger No. of Capacity Extinguishers 7 through 30 31 through 60 2 61 or more 3
(2) There must be a hand fire extinguisher for the flight crewmembers.
(3) There are no requirements for extinguishing systems or hand extinguishers for accessible cargo or baggage compartments in transport category rotorcraft. Use the hand extinguisher guidance provided in chapter 4, paragraph 6 of this AC for these compartments.
c. Small Airplanes. Title 14 CFR §§ 23.851 and 91.513(c) requires a minimum number of hand extinguishers to be installed on small part 23 airplanes.
(1) At least one hand fire extinguisher must be located within easy access of the seated pilot.
(2) At least one hand fire extinguisher must be in the passenger compartment of an airplane that accommodates more than six passengers. The extinguisher must minimize the hazard of toxic gas concentration.
Appendix 1 Appendix 1. List of Acronyms 14 CFR Title 14, Code of Federal Regulations Advisory Circular ACO Aircraft Certification Office AD Airworthiness Directive AFM Airplane Flight Manual American Society of Testing and Materials Civil Aviation Authority Code of Federal Regulations Cabin Pressure Altitude Department of Transportation U.S. Environmental Protection Agency FAA Federal Aviation Administration FAATC FAA Technical Center FC Fluorocarbon FCOM Flight Crew Operations Manual FIC Fluoroiodocarbon FK Fluoroketone FM Factory Mutual Research Corp.
HCFC Hydrochlorofluorocarbon HF Hydrogen Flouride HFC Hydrotluorocarbon ICA Instructions for Continued Airworthiness ISO International Organization for Standardization LOAEL Lowest Observable Adverse Effect Level MF Multiplication Factor MPS Minimum Performance Standard No Observable Adverse Effect Level National Fire Protection Association Perfluorocarbon Protective Breathing Equipment Physiologically Based Pharmacokinetic Personal Digital Assistant Portable Electronic Device Regulatory Guidance Library Radio Technical Corporation of America Society of Automotive Engineers Significant New Alternatives Policy Air Change Time Technical Standard Order Underwriters Laboratories United States Coast Guard W/V Weight per Unit Volume (W/V) Ratio %V/V Volume Percent A1-1
Appendix 2 Appendix 2. Definitions and Terms The following definitions and terms apply when following the procedures outlined in this AC:
1. Air Change Time. t. is the time in minutes, it takes for the inflow of fresh air into a compartment, with a volume equivalent to the volume of the compartment.
2. Cabin Pressure Altitude is specified for transport aircraft by regulation to be the air pressure in the cabin or compartment of a commercial airliner and it must not be lower than that found at an altitude of 8,000 ft (2,438 m) under normal operating conditions, per § 25.841(a) Cargo Aircraft are aircraft configured solely to carry cargo and no personnel other than the flight crew and any additional crew required for the care of the cargo.
4. Clean Agent is electrically nonconducting, volatile or gaseous fire extinguishant that does not leave a residue upon evaporation. The word agent as used in this circular means clean agent unless otherwise indicated.
5. Combi Aircraft are designed/configured to transport both passengers and cargo on the same level within the fuselage.
6. Compartment is an enclosed space on an aircraft. Examples of compartments are a flight deck, a crew rest, and a cabin. The aircraft cabin is considered one compartment.
7. Dry Chemical is a mixture of finely divided solid particles, usually sodium bicarbonate, potassium bicarbonate, or ammonium phosphate-based with added particulate material supplemented by special treatment to provide resistance to packing, and moisture absorption (caking) and to promote proper flow characteristics.
Dry Powder is solid materials in powder granular form designed to extinguish class D combustible metal fires by crusting, smothering, or heat transferring means.
9. Flight Crew are responsible for the operation and management of the aircraft flight controls, engines, and systems, including, but not limited to, pilot in command (captain), first officer (copilot), second officer (flight engineer).
10. Flight Deck is the compartment of the aircraft arranged for use by the flight crew in operating the aircraft.
11. Galley is the area of the aircraft for storing, refrigerating, heating and dispensing of food and beverages.
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10/XX/10 AC 20-42D Appendix 2
12. Halocarbon Agent is comprised primarily of one or more organic compounds containing one or more of the elements fluorine, chlorine, bromine, or iodine. Halocarbon agents are electrically non-conducting, volatile liquids, or gaseous fire extinguishants. As "clean agents", they do not leave a residue on evaporation. Halocarbon agents (halons and halon replacements) that are currently commercialized include the hydrochlorofluorocarbons (HCFCS), perfluorocarbons (FCs or PFCs), hydrofluorocarbons (HFCs), fluoroiodocarbons (FICs), and fluoroketones (FKs), as well as the completely halogenated halocarbons (halons). Halocarbon agents are multipurpose class A, B, Crated agents and are most effective on Class B and C fires.
Advantages of halocarbon agents include low cold shock characteristics on electronic equipment, no degradation of visual acuity, and low pressure.
13. Halocarbon Blend is a mixture of 2 or more halocarbon agents in a portable extinguisher.
14. Halon is a short derivation for "halogenated hydrocarbon." The chemical structure is identified as a four digit number representing, respectively, the number of carbon, fluorine, chlorine, and bromine atoms present in one molecule. Both Halon 1211 and Halon 1301 are liquefied gases and typified as "clean agents." Halons primarily extinguish fire by chemically interrupting the combustion chain reaction rather than by heat removal or physically smothering.
15. Halon Equivalent Extinguisher is an extinguisher containing a clean agent which meets the MPS for hand-held fire extinguishers (see appendix 3 reference paragraph 7s of this AC).
Equivalency does not refer to agent weight, but the effectiveness of extinguishing a fire. Halon replacement extinguishers may be more than twice the weight of halon extinguishers.
16. Halon 1211 has the chemical name bromochlorodifluoromethane, CBrC1F2. Halon 1211 is a multipurpose, Class A, B, C rated agent effective against flammable liquid fires. Due to its relatively high boiling point of +26°F (-4°C). Halon 1211 discharges as an 85 percent liquid stream offering a long agent throw range.
17. Halon 1301 has the chemical name bromotrifluoromethane, CBrF3. Halon 1301 is recognized as a multipurpose agent having Class A, B, C capability in total flooding systems.
However, Halon 1301 offers limited Class A capability when used in portable fire extinguishers.
The boiling point for this agent is -72°F (-57.8°C). Halon 1301 discharges as a gas.
18. Halon Replacement Agents are any clean agents which can be either a non-halon (halocarbon agent) or halon alternative (all other substitute agents) that have SNAP approval by the U.S. EPA and meet the MPS for hand fire extinguishers.
19. Hand Fire Extinguisher is an approved, aircraft portable fire extinguisher which can be used by aircraft occupants to combat accessible, incipient, on-board fires.
21. HFC-227ea is an extinguishing agent that is comprised of the chemical 1,1,1,2,3,3,3- heptatluoropropane (CF CHFCF3). The boiling point of the agent is 2.5°F (-16.4°C). Due to this boiling point, HFC-227ea is discharged as a mixed liquid and vapor stream which readily evaporates. It is a multipurpose agent with class A, B and C capability.
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Appendix 2
22. HFC-236fa is an extinguishing agent that is comprised of the chemical 1,1,1,3,3,3 hexafluoropropane (CF3CH,CF3). The boiling point of the agent is +29.5°F (-1.4°C). Due to its relatively high boiling point, HFC-236fa discharges predominately as a liquid stream which readily evaporates. It is a multipurpose agent with class A, B and C capability.
23. HCFC Blend B is an extinguishing agent that is a tertiary blend comprised primarily of the chemical 2,2-dichloro-1,1,1-trifluoroethane HCFC-123, (CFCHCI). Two inert gases are blended with the HCFC-123 to enhance flow distribution and fire extinguishing performance.
The boiling point of the blend is 80.6°F (27°C). Due to its high boiling point, HCFC Blend B discharges primarily as a liquid stream which readily evaporates. It is a multipurpose agent with class A, B, and C capability.
24. Labeled equipment or materials have an attached label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
25. Listed refers to equipment, materials or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services. The organization maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and who's listing states that the equipment, material or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.
26. Listing Mark is a certification mark allowed to be carried as a stamp of approval by nationally recognized standards/testing organization.
27. Lithium Ion Battery is a rechargeable battery that has an anode made from a metal oxide composite containing lithium ion, and a cathode made from a specialized carbon material.
Charge and discharge of the battery is facilitated by the movement of lithium ions in electrolytic solutions. Lithium ion batteries are used in small electronic devices such as pagers, portable computers, camcorders, and portable telephones.
28. Lithium Primary Battery is a rechargeable battery that has a lithium anode and a cathode system consisting of carbon and either thionyl chloride or sulfuryl chloride.
29. Lowest Observable Adverse Effect Level (LOAEL) is the lowest concentration at which an adverse physiological or toxicological effect has been observed in dogs.
30. Maximum Certificated Occupant Capacity is the maximum number of persons that can be carried for each specific aircraft model as certified by the authority having jurisdiction.
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Appendix 2
31. Minimum Performance Standard (MPS) for Hand Extinguishers refers specifically to two tests that hand extinguishers containing halon replacement agents must pass. See appendix 3 reference paragraph 7s. These fire tests demonstrate equivalent fire extinguishing performance currently used in aircraft and assess the toxicity of the decomposition products.
32. Minimum Safe Volume refers to the smallest compartment volume into which one extinguisher could be discharged, assuming perfect mixing of agent, without posing a toxicity hazard. Minimum safe volumes are dependent on the agent, the agent weight, ventilation, and pressure altitude of the discharge.
33. Neat in this context refers to un-decomposed agent.
34. No Observable Adverse Effect Level (NOAEL) is the highest concentration at which no adverse physiological or toxicological effect has been observed in dogs.
35. Physiologically Based Pharmacokinetic (PBPK) Model is a mathematical model for human health risk assessment and investigation of toxicity. The health concern for halocarbons, including halons, is cardiac sensitization which occurs at a fixed target arterial concentration.
The model estimates the allowable arterial blood concentration as a function of agent exposure time to establish both the concentration of agent and duration to which personnel could be safely exposed. The PPK modeling is endorsed by the U.S. EPA and the NFPA.
36. Rated/Rating is a numerical value assigned to an extinguisher based on its fire extinguishing capability.
37. Safe Human Exposure Concentrations are based on PPK modeling. Safe human concentrations are exceeded when the simulated arterial concentration exceeds the target arterial concentration.
38. Small Aircraft are defined by part 23.
39. SNAP Program is EPA's significant new alternatives policy (SNAP) program to evaluate and regulate substitutes for ozone depleting chemicals that are being phased out under the stratospheric ozone protection provisions of the Clean Air Act.
40. Time of Useful Consciousness is the time available to don an oxygen mask without assistance.
41. Unventilated Compartment for the purposes of the AC is a compartment where the air change time is not known or exceeds 6 minutes.
42. Ventilated Compartment is a compartment where the air change time is known and does not exceed 6 minutes.
43. Volume Percent (% v/v) is the gas volume in liters per 100 liters of the resulting gas mixture, e.g. 2% v/v Halon 1211 mixture contains 2 liters Halon 1211 per 100 liters volume.
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