systems and structure are not adversely affected. For certification purposes, test data with the actual design configuration and possible fire sources would have to be provided. The temperature and heat load time history measurements at various locations above, around, and below the FCC are needed to ensure the continued safe function of adjacent systems and structure. The time history data should be used to establish the length of protection time afforded by the system and subsequent AFM limitations for cargo or baggage compartment fire protection times. The operator would then use these times for route planning purposes.
6.3.3.5 FCCs (when used in conjunction with a pallet) should meet, at a minimum, the flammability requirements as described above in paragraph 6.3.3.2 of this AC.
6.3.3.6 The pallet used in conjunction with an FCC should meet, at a minimum, the flammability requirements of part 25, appendix F, part I, paragraphs (a)(1)(ii) and (a)(2)(iii), i.e., be self-extinguishing when tested vertically in accordance with part I, paragraph (b)(4), and have no flame penetration during application of the specified flame source when subjected to the 45-degree angle test defined in part I, paragraph (b)(6).
6.3.3.7 The net used in conjunction with an FCC should meet, at a minimum, the requirements of TSO-C90 and flammability requirements of part 25 appendix F, part I, paragraph (a)(1)(ii), i.e., be self-extinguishing when tested vertically in accordance with part I paragraph (b)(4).
6.3.3.8 If a design uses FCCs or FRCs for fire protection, compliance with the smoke or fire detection requirements in § 25.858 may present unique challenges. Crew awareness is a critical factor to ensure adequate fire protection on airplanes. Applicants for FAA approval should consider the use of infrared (IR) cameras or other means to ensure adequate detection of a fire within the cargo compartment where FCCs and FRCs are used.
Full-scale or high-fidelity fire testing may be necessary to ensure that the smoke or fire detection system can provide adequate detection.
6.3.3.9 If an applicant’s proposed design for a Class F cargo compartment relies on fire containment (e.g., fire hardened containers/pallets, FRCs and/or FCCs placed over palletized loads or non-fire hardened containers), then the applicant should be prepared to demonstrate the continued effectiveness of those means after incorrect usage or cargo loading errors.
6.3.3.10 If an applicant’s proposed design for a Class F cargo compartment requires FCCs or FRCs or other means to afford fire protection, then the applicant should incorporate means to prevent the carriage of cargo in standard containers or pallets. Instructions for loading cargo should warn that all cargo must be placed within the approved design (i.e., FCCs, FRCs, or other approved methods of providing fire protection). In 10
addition, to ensure only approved designs are used to carry cargo, applicants may incorporate within the approved design such features as, but not be limited to:
• Physical features at the container/pallet-to-cargo compartment floor interface (e.g., a unique locking mechanism); or
• Operational procedures, such as requiring airplane crew verification of cargo loading before every flight; or
• A suitable detection system (e.g., radio-frequency identification tags on approved FCCs, FRCs or other approved methods) that would warn the crew and prevent a non-approved cargo configuration from being loaded.
6.4 Extinguishing Agent.
6.4.1 In order to effectively extinguish or control a fire in a Class B or Class F cargo or baggage compartment, sufficient fire extinguishing agent must be allocated. The FAA requirements for hand fire extinguishers and fire extinguishing agents are included in § 25.851(a). General guidance on this topic is included in AC 20-42. The FAA’s requirements for built-in fire extinguishing/suppression systems and fire extinguishing agent are included in § 25.851(b). AC 25.851-1 contains guidance for built-in fire extinguishing/suppression systems. Both AC 20-42 and AC 25.851-1 include guidance on halon and non-halon fire extinguishing agents in hand fire extinguishers and built-in fire extinguishing/suppression systems. However, the FAA has not issued substantive guidance addressing installation issues associated with non-halon fire extinguishing agent applications. Instead of such guidance, the FAA will expect that each non-halon agent has successfully passed the minimum performance standard3 for that application
(e.g., lavatory trash receptacle fire extinguisher, hand fire extinguisher, engine/auxiliary power unit fire extinguishing system, or cargo compartment fire extinguishing/suppression system). Meeting these standards is one way to ensure the performance of the proposed non-halon agent provides protection equivalent to that provided by halon and that the applicant has addressed installation issues associated with the specific application. Depending on the properties of the agent, the means to deliver the agent, and the means to determine the concentration of the agent, full-scale or high-fidelity fire testing may be necessary to ensure that the non-halon fire extinguishing/fire suppression system provides adequate performance. AC 20-42 provides an acceptable means to implement the requirement in § 25.851(a) for at least one hand fire extinguisher to be located in the pilot compartment, at least one readily accessible hand fire extinguisher to be available for use in each Class A or Class B cargo/baggage compartment and in each accessible Class E or Class F cargo/baggage compartment, and for one or more hand fire extinguishers to be located in the passenger compartment of airplanes with a passenger seating capacity of 7 or more.
3 Reports available at the FAA William J. Hughes Technical Center Fire Safety Branch website:
http://www.fire.tc.faa.gov.
6.5 Fire Control.
To “control a fire” (§ 25.857(f)(2)) means that the fire does not grow to a state where damage to the airplane or harm to the passengers or crew occurs during the length of time of protection that the fire protection system is demonstrated to afford during certification testing. This in turn means that critical airplane systems and structure adjacent to the cargo compartment are not adversely affected, and the temperature and air contaminants in areas occupied by passengers and crew do not reach hazardous levels.
6.5.1 The applicant should provide adequate protection from the effects of a fire for all cockpit voice and flight data recorders and wiring, windows, primary flight controls (unless it can be shown that a fire cannot cause jamming or loss of control), and other systems, structure, and equipment within or adjacent to the compartment that are required for safe flight and landing.
6.5.2 An applicant must demonstrate for Class B and Class F cargo compartments that hazardous quantities of smoke, flames, extinguishing agent, or noxious gasses do not enter any compartment occupied by passengers or crewmembers. AC 25-9 provides guidance concerning smoke penetration testing.
6.5.3 If an airplane has a Class B or Class F cargo compartment, portable protective breathing equipment must be provided for the appropriate crewmembers in accordance with § 25.1439. If the airplane is operated under part 121, the protective breathing equipment must meet the more stringent standards of § 121.337.
6.5.4 Additional protective breathing equipment or breathing gas supply, and additional fire extinguishers, may be required to ensure that the fire can be controlled for the time the airplane is expected to be in the air after onset of a fire. As required in § 25.851(a), 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. Depending on the proposed fire extinguishing agent and quantity of the agent provided, full-scale or high-fidelity fire extinguishing testing may be necessary to ensure an adequate level of protection.
6.6 Reclassification.
As explained in paragraph 5.4 of this AC, the Class D cargo compartment has been eliminated from the regulations due to limited effectiveness in providing fire protection.
The Class F compartment is not intended to be a Class D compartment with smoke or fire detection. It is not acceptable to simply reclassify a compartment as Class F and use the same fire protection methodology as was used for Class D compartments. Means for controlling ventilation in Class D cargo compartments were shown to be ineffective in controlling a fire in many cases. This was evidenced by a number of accidents and incidents involving fires in Class D cargo compartments as discussed in Docket No. 28937, Notice of Proposed Rulemaking No. 97-10 (62 FR 32412, June 13, 1997), and Amendment 25-93 (63 FR 8032, February 17, 1998).
7 PROCEDURES AND LIMITATIONS.
7.1 To ensure that the contents of Class B and F compartments are accessible to crewmembers seeking to combat a fire, the cargo or baggage loading limitations and any operational limitations or procedures provided are expected to be identified with placards in the compartment. The loading and operational limitations must also be addressed in the appropriate weight and balance or loading document.
7.2 Any operational limitations or procedures necessary to ensure the effectiveness of the fire protection system for Class B and Class F cargo and baggage compartments should be clearly defined in the AFM. This should include such items as any changes to the ventilation system to prevent the entrance of smoke or gasses into occupied areas, use of hand fire extinguishers, use of protective breathing equipment, use of protective clothing, and use of the FCCs and FRCs in Class F cargo compartments. For example, the use of FCCs and FRCs in Class B cargo compartments do not afford a single crewmember immediate access to the source of the fire, which is critical in extinguishing the fire. The purpose of FCCs and FRCs is to control the fire within the cargo container without exposing the airplane to damage from a fire. The opening of an FCC or FRC to fight a fire would negate the benefits of their design. Therefore, the FAA may restrict use of FCCs and FRCs to certain classes of cargo compartments. The applicant and the ACO should work closely with the FAA Flight Standards organization (Aircraft Evaluation Group) to ensure that additional training necessary for crewmembers assigned to combat fires is adequately addressed.
7.3 Any time limit for a cargo or baggage compartment fire protection system, or other conditions or procedures related to combating a fire in a compartment, should be clearly defined in the AFM.
8 AFM CONSIDERATIONS.
8.1 Any crewmember designated to combat a fire in a Class B compartment will need special training. Fires occurring in luggage are difficult to extinguish completely and rekindling may occur. Crewmembers designated to combat fires in Class B compartments should be trained to check periodically to ensure that a fire has not grown back to hazardous proportions. The applicant and the ACO should work with the appropriate organizations, including the operators, to ensure that training in the use of protective breathing equipment, fire extinguishers, protective gloves and clothing is provided.
8.2 AFMs should contain instructions to land at the nearest suitable airport following smoke or fire detection, unless it can be positively determined that the fire is extinguished.
8.3 In the unusual event that occupancy of a Class B or F compartment during flight is approved by the FAA, that approval may require limitations in the AFM.
8.4 Any loading restrictions associated with access to cargo or baggage or special containers, including the use of FCCs and FRCs in Class F cargo compartments, should be clearly identified in the AFM. This would include, but not be limited to, placement of luggage in a Class B compartment or identification of special containers or covers associated with fire protection in a Class F compartment. If FCCs or FRCs are used in conjunction with a Class F cargo compartment, they should be easy to install and sufficiently durable to withstand in-service conditions.
If you have any suggestions for improvements or changes to this AC, you may use the Advisory Circular Feedback form at the end of this AC.
Jeffrey E. Duven Manager, Transport Airplane Directorate Aircraft Certification Service 14
Advisory Circular Feedback If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by (1) emailing this form to 9-AWA-AVS AIR500-Coord@faa.gov or (2) faxing it to the attention of the Aircraft Certification Service Directives Management Officer at (202) 267-3983.
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