because tobacco smoke is also detected, as evidenced by continuing reports of lavatory smoke alarms due to smoking in lavatories. To the extent that smoke detectors do not detect cigarette smoke, there is a perception that they are not properly designed and/or functioning. Therefore, it is the FAA position that industry be encouraged to do all they can to ensure that lavatory smoke detectors not only function well to detect smoke from lavatory fires, but also function to effectively deter lavatory smoking by efficiently detecting cigarette smoke as well.
(d) When the airframe manufacturers were approached by their customers to install smoke detectors as part of the type design, the FAA was requested to provide certification requirements covering the installation. The guidance provided was the following:
1 The detectors had to meet §§ 25.1301(a) and (d) and 25.1309(a). This meant that environmental, as well as performance, standards had to be considered.
2 Testing was to be performed in flight, and the combustible material used for testing was to be representative of what would be expected to burn in a lavatory waste bin,
e.g., paper towels.
3 As a design goal, the detector was to provide a warning within one minute after a fire started.
4 If unpressurized flight was to be allowed, testing under those conditions had to be performed.
(e) It has been suggested that Technical Standard Order (TSO) TSO-C1c might be appropriate for use in approving lavatory smoke detectors. TSO-C1c provides standards for approval of detectors to be used in cargo compartment smoke detection systems. The TSO requirements are not considered appropriate for lavatory smoke detection, as the environment and products of combustion to be detected are both different from that to be expected in a cargo compartment fire. This is not to imply, however, that a TSO-C1c detector would be unacceptable. With appropriate testing, and recognizing that the environment in a lavatory is different than a cargo compartment, a detector authorized under the TSO might be an acceptable choice.
(f) TSO-C1c authorization should not be a requirement for lavatory smoke detector certification. The certification basis for the lavatory smoke detector installation must include §§ 25.1301 and 25.1309, as discussed above, plus any other appropriate sections such as those addressing structural or electrical supply requirements. If application for certification occurs after the effective date of Amendment 25-74 (April 15, 1991), § 25.854 would also be applicable. For these installations, the intended function is to detect smoke resulting from a fire occurring in a lavatory.
(2) Approval of Lavatory Fire Extinguishers Containing Agents Other Than Halon.
The following policy is extracted from an FAA memorandum dated March 31, 1997, to distribute a minimum performance standard for use in certifying lavatory fire extinguishers.
(a) Sections 25.854(b) and 121.308(b) require that each lavatory on passengercarrying transport category airplanes with a passenger capacity of 20 or more, be equipped with a built-in fire extinguisher for each disposal receptacle for towels, paper, or waste located within the lavatory. The fire extinguisher must be designed to discharge automatically into each disposal receptacle upon occurrence of a fire in the receptacle. Currently, although not required by airworthiness regulations, the typical aircraft lavatory disposal receptacle fire extinguisher uses Halon as the fire extinguishing agent.
(b) Halon production was banned as of January 1, 1994, under the provisions of the Montreal Protocol for those subscribing nations, due to its identification as an ozone destroying compound. The Environmental Protection Agency has exempted the aviation industry from the ban on the use of Halon. However, the FAA established the International Halon Replacement Working Group to help identify acceptable replacements for halons. A key aspect of this work is to define minimum performance standards which can be used to assess the performance of candidate replacement agents to assure that they will provide protection equivalent to Halon. Standards are being developed for fire extinguishers used in: lavatory trash receptacles; cargo compartments; engines and auxiliary power units; and hand held extinguishers. The first of these minimum performance standards is published in report number DOT/FAA/AR-96/122, titled “Development of a Minimum Performance Standard for Lavatory Trash Receptacle Automatic Fire Extinguishers,” dated February 1997.
(c) The minimum performance standard in report DOT/FAA/AR-96/122 provides guidance on acceptable methods of compliance to § 25.854. The performance of an alternative agent needs to be measured against a standard test method. This document establishes fire load, trash disposal receptacle test article, test procedures, and pass/fail criteria for built-in extinguishers for lavatory disposal receptacles.
e. References. The addresses for ordering the latest revision of advisory circulars (AC), technical standard orders (TSO), and other referenced documents listed below can be found in the Appendix to this AC.
AC 25-9A, Smoke Detection, Penetration, and Evacuation Tests and Related Flight Manual Emergency Procedures.
Technical Standard Order TSO-C1c, Cargo and Baggage Compartment Smoke Detection Instruments.
FAA Report DOT/FAA/AR-96/122, Development of a Minimum Performance Standard for Lavatory Trash Receptacle Automatic Fire Extinguishers.
37. SECTION 25.855 - CARGO OR BAGGAGE COMPARTMENTS.
a. Rule Text.
For each cargo and baggage compartment not occupied by crew or passengers, the following apply:
(a) The compartment must meet one of the class requirements of 25.857.
(b) Class B through Class E cargo or baggage compartments, as defined in
25.857, must have a liner, and the liner must be separate from (but may be attached to) the airplane structure.
(c) Ceiling and sidewall liner panels of Class C compartments must meet the test requirements of Part III of appendix F of this Part or other approved equivalent methods.
(d) All other materials used in the construction of the cargo or baggage compartment must meet the applicable test criteria prescribed in Part I of appendix F of this Part or other approved equivalent methods.
(e) No compartment may contain any controls, wiring, lines, equipment, or accessories whose damage or failure would affect safe operation, unless those items are protected so that-
(1) They cannot be damaged by the movement of cargo in the compartment; and
(2) Their breakage or failure will not create a fire hazard.
(f) There must be means to prevent cargo or baggage from interfering with the functioning of the fire protective features of the compartment.
(g) Sources of heat within the compartment must be shielded and insulated to prevent igniting the cargo or baggage.
(h) Flight tests must be conducted to show compliance with the provisions of
25.857 concerning-
(1) Compartment accessibility,
(2) The entries of hazardous quantities of smoke or extinguishing agent into compartments occupied by the crew or passengers, and
(3) The dissipation of the extinguishing agent in Class C compartments.
(i) During the above tests, it must be shown that no inadvertent operation of smoke or fire detectors in any compartment would occur as a result of fire contained in any other compartment, either during or after extinguishment, unless the extinguishing system floods each such compartment simultaneously.
[Doc. No. 5066, 29 FR 18291. Dec. 24, 1964, as amended by Amdt. 25-15, 32FR 13266, Sep. 20, 1967; Amdt. 25-32, 37 FR 3972, Feb. 24, 1972; Amdt. 25- 60, 51 FR 18242, May 16, 1986; Amdt. 25-72, 55 FR 29784, Jul. 20, 1990; Amdt.
25-93, 63 FR 8048, Feb. 17, 1998]
b. Intent of Rule. This rule contains the material standards and design considerations for cargo compartment interiors; the statement that each cargo compartment must meet one of the class requirements of § 25.857; and the flight tests which must be conducted for certification.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The standards in section 4b.382 of the CAR, cargo and baggage compartments, and section 4b.384, proof of compliance, of the Civil Air Regulations (CAR), and were carried over essentially unchanged to 96
§ 25.855 of 14 CFR. This section contains the standards related to those requirements that must be demonstrated by flight test.
(1) Amendment 25-15 (September 20, 1967) added reference to the requirements of § 25.853 for materials, rather than stating the materials must be at least flame resistant.
(2) Amendment 25-32 (February 24, 1972) specifically addressed insulation blankets and cargo covers meeting the requirements of § 25.853(b-3).
(3) Amendment 25-60 (May 16, 1986) added more stringent flammability standards for cargo compartment materials.
(4) Amendment 25-72 (July 20, 1990) made editorial changes and relocated the material flammability requirements to § 25.853 and Appendix F of part 25.
(5) Amendment 25-93 (February 17, 1998) revised §§ 25.855(c) and 25.857(c)(2) to eliminate reference to Class D cargo compartments. . These amendments upgraded the fire safety standards for cargo or baggage compartments in certain transport category airplanes by eliminating Class D compartments as an option for future type certification. Compartments that can no longer be designated as Class D must meet the standards for Class C or Class E compartments, as applicable. The Class D compartments in certain transport category airplanes manufactured under existing type certificates and used in passenger service must meet the fire or smoke detection and fire suppression standards for Class C compartments by early 2001 for use in air carrier, or most other commercial service. The Class D compartments in certain transport category airplanes manufactured under existing type certificates and used only for the carriage of cargo must also meet such standards or the corresponding standards for Class E compartments by that date for such service. These improved standards are adopted to increase protection from possible in-flight fires.
(6) Harmonization. This regulation is the subject of a Federal Aviation Regulations/Joint Aviation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group is recommending revisions to §§ 25.855 and 25.857, and a new advisory circular may evolve from that process.
As a result of this process, Class B compartments may be revised and a new Class F compartment may be proposed.
d. Policy/Compliance Methods. For guidance on compliance with this requirement, refer to the preambles of this rule and the following information. In accordance with § 25.855(h), flight tests must be conducted to show compliance with the standards concerning: compartment accessibility, smoke and extinguishing agent penetration into occupied areas, and the dissipation of extinguishing agent. Cargo compartment smoke detection testing should be conducted in flight, and is usually accomplished concurrently with the smoke penetration tests. Advisory Circular 25-9A contains guidance regarding smoke detection and penetration testing. Where suitable data is available from previous certification flight test programs of the same airplane 97
model, the cognizant ACO may review an applicant’s proposal on a case by case basis and, if satisfactory, may accept certification ground tests for smoke detection purposes.
(1) Halon Concentration. The following policy is extracted from an FAA memorandum dated March 9, 1998, regarding the adequacy of Halon concentration levels needed for certification of cargo compartments in loaded vs. empty configurations.
(a) Traditionally cargo fire extinguishing systems have been certified by demonstrating five percent initial Halon concentration levels and subsequent concentration levels of three percent, when the cargo compartment has been in the empty configuration. The majority of applicants in previous certification programs have not tested or analyzed a loaded cargo compartment configuration.
(b) Recent tests and analyses have raised concern regarding the adequacy of Halon concentrations in a loaded cargo compartment. Regardless of this concern, the Transport Airplane Directorate does not currently have any written guidance, stating that applicants must test or analyze the loaded configuration. Requiring testing or analysis to show Halon concentration levels remain at or above three percent in the loaded cargo compartment may be considered beyond the scope of what the FAA can require without public comment. Although some applicants have previously considered loaded cargo compartments, we do not require testing or analysis for the loaded cargo condition at this time.
NOTE: This may be considered a safety issue that the Transport Airplane Directorate may address in future policy.
(2) Class D to Class C Conversion. The following guidance is extracted from an FAA memorandum dated October 29, 1997, regarding criteria for certification of cargo compartments to be converted from Class D to Class C.
(a) On June 9, 1997, the FAA issued a Notice of Proposed Rulemaking, Docket No. 28937, Notice 97-10 (62 FR 32412, dated June 13, 1997), that proposes to upgrade the fire safety standards for cargo or baggage compartments in certain transport category airplanes by eliminating Class D compartments as an option for future certification. This notice also proposes that Class D compartments in certain transport category airplanes manufactured under existing type certificates and used in passenger service would have to meet the fire detection and suppression standards for Class C compartments by early 2001 for use in air carrier, commuter, on demand, or most other commercial service.
(b) A policy memorandum, dated August 18, 1997, was issued in response to questions concerning what guidance was available regarding the certification of smoke detection/penetration and fire suppression system evaluations in anticipation of the final rule associated with Notice 97-10. After considering industry objections to our memorandum of August 18, 1997, the information in our memorandum is revised to read: Fire Suppression Tests.
Several companies have objected to the guidance provided under “Fire Suppression Tests” in the memorandum dated August 18, 1997, even though some recent certification projects have been 98
approved using that guidance. Some manufacturers argued that they used a number of techniques to establish a minimum Halon concentration, including a volumetric averaging technique. The certification criteria contained under “Fire Suppression Tests” in our memorandum of August 18, 1997, is considered new policy for Class D to C conversions.
Therefore, the manufacturers may continue to use the certification techniques they have been using, including volumetric averaging, to establish the minimum concentration of Halon for fire suppression.
(aa) At the FAA/Industry workshop of April 22-24, 1997, the FAA’s Technical Center expressed concern that the current Halon measuring technique using volumetric averaging may allow a concentration of Halon insufficient to suppress a fire. The FAA Technical Center tests have shown that Halon, having a higher density than air, settled in the cargo compartment. Further, the tests showed that fires may reignite at the higher water lines in the cargo compartment due to insufficient Halon concentration even though the average volumetric concentration of Halon was considered adequate. There was no subsequent measured increase in Halon concentration near the fire due to convective stirring. This information was presented to and discussed with Industry at the April 22-24,1997, workshop and is the basis of the “Fire Suppression Tests” guidance provided in our memorandum of August 18, 1997.
(bb) The use of the technique of volumetric averaging to determine the minimum Halon concentration is questionable in light of the testing accomplished by the FAA’s Technical Center. Therefore, establishing minimum Halon concentrations near the ceiling should be considered. Applicants may elect to take advantage of this information in measuring the Halon concentration in their tests even though the FAA will not require this technique at this time. Furthermore, the Transport Standards Staff will develop an Advisory Circular (AC) that addresses measuring the minimum acceptable level of Halon in all cargo compartments.
(c) The rest of the memorandum, dated August 18, 1997, was revised as follows, and may be used for guidance:
(d) System Reliability. Use advisory material appropriate to the certification basis.
When applying AC 25.1309-1A, the following is suggested: Detection and suppression systems are considered complex in terms of paragraph 6d of the AC. A failed detection system and/or a failed suppression system in conjunction with a fire should be considered a catastrophic event.
Therefore, utilizing figure 2 of AC 25.1309-1A, knowing the system is complex and the failure event is a catastrophic event, the depth of analysis should include both a qualitative and quantitative assessment (reference paragraphs 8d, 9, and 10 of the AC).
(e) Dispatch. For dispatch relief, the systems should be tested in the proposed Master Minimum Equipment List (MMEL) configurations. Dispatch may be allowed with detection or suppression systems inoperative in a cargo compartment provided the AFM prohibits the carriage of cargo in the affected compartment.
(f) Smoke Detection/Penetration/Evacuation Tests. Use AC 25- 9A, “Smoke Detection, Penetration, and Evacuation Tests and Related Flight Manual Emergency 99
Procedures,” supplemented by ANM-100 memorandum, dated June 18, 1997, and the referenced video. The supplemental memorandum elaborates on a small smoldering fire for use in detection tests.
(g) If the applicant disagrees with any of the guidance above, then an issue paper can be created identifying the disagreement as an issue and coordinate it with the FAA.
(3) Protection of Critical Equipment in Class E Cargo Compartments. The following guidance is extracted from an FAA Generic Issue Paper regarding protection of critical equipment in Class E cargo compartments.
(a) Statement Of Issue.
1 A specific requirement to protect critical systems and equipment in Class E cargo compartments from fire damage does not exist. Both Class B and Class E cargo compartments are similar in that they do not have fire suppression systems. On Class B compartments, it is assumed that the fire can be controlled manually. On Class E compartments, the fire is controlled by shutting off ventilating airflow. In both types of cargo compartments fires can quickly reach dangerous proportions because no fast-acting suppression system is installed. In a Class E compartment, an uncontrolled fire could damage critical systems and equipment to compromise flight safety before ventilating airflow could be effectively shut off.
For this reason, protection of these critical systems and equipment must be ensured.
(b) Background.
1 The FAA has issued Airworthiness Directives (AD) 91-10-02, which requires certain design, equipment, and operational changes to maximize fire protection on "Combi" Class B cargo compartments. One of these requirements is to ensure appropriate protection of cockpit voice and flight data recorders, windows, primary flight control systems (unless it can be shown that a fire could not cause jamming or loss of control), and other equipment within the compartment that is required for safe flight and landing. If protective covers are used, they must be constructed of materials that meet the flame penetration resistance requirements of § 25, 14 CFR, appendix F, part III [Amendment 25-60].
2 The generic model airplane main deck Class E cargo compartment is similar to the main deck Class B cargo compartment on generic model "Combis." Therefore, similar protection must be afforded to the affected systems on the generic model aircraft.
(c) FAA Position.
1 Section 21.21(b)(2) of 14 CFR requires that no feature or characteristic of an airplane make it unsafe for the category in which certification is requested. Based on the similarities of the generic model aircraft Class E cargo compartment to the generic model aircraft "Combi" Class B cargo compartment, a concern exists that the unsafe conditions identified on "Combis" will also exist on the generic model aircraft.
2 Prior to issuance of the Generic Model Airplane Type Certificate, it must be shown by design or analysis that adequate fire protection has been provided to the cockpit voice and flight data recorders, windows, primary flight controls (unless it can be shown that a fire could not cause jamming or loss of control), and other systems and equipment within the compartment that is required for safe flight and landing. If protective covers are used, they must be constructed of materials that meet the flame penetration resistance requirements of 14 CFR part 25, appendix F, part III [Amendment 25-60].
e. Reference. The address for ordering the latest revision of advisory circulars and other referenced documents listed below can be found in the Appendix to this AC.
AC 25-9A; Smoke Detection, Penetration, and Evacuation Tests and Related Flight Manual Emergency Procedures.
38. SECTION 25.857 - CARGO COMPARTMENT CLASSIFICATION.
a. Rule Text.
(a) Class A. A Class A cargo or baggage compartment is one in which-
(1) The presence of a fire would be easily discovered by a crewmember while at his station; and
(2) Each part of the compartment is easily accessible in flight.
(b) Class B. A Class B cargo or baggage compartment is one in which-
(1) There is sufficient access in flight to enable a crewmember to effectively reach any part of the compartment with the contents of a hand fire extinguisher;
(2) When the access provisions are being used, no hazardous quantity of smoke, flames, or extinguishing agent, will enter any compartment occupied by the crew or passengers;
(3) There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station.
(c) Class C. A Class C cargo or baggage compartment is one not meeting the requirements for either a Class A or B compartment but in which-
(1) There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station;
(2) There is an approved built-in fire-extinguishing or suppression system controllable from the cockpit;
(3) There are means to exclude hazardous quantities of smoke, flames, or extinguishing agent, from any compartment occupied by the crew or passengers;
(4) There are means to control ventilation and drafts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment.
(d) [Reserved] 101
(e) Class E. A Class E cargo compartment is one on airplanes used only for the carriage of cargo and in which-
(1) (Reserved)
(2) There is a separate approved smoke or fire detector system to give warning at the pilot or flight engineer station;
(3) There are means to shut off the ventilating airflow to, or within, the compartment, and the controls for these means are accessible to the flight crew in the crew compartment;
(4) There are means to exclude hazardous quantities of smoke, flames, or noxious gases, from the flight crew compartment; and
(5) The required crew emergency exits are accessible under any cargo loading condition.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-32, 37 FR 3972, Feb. 24, 1972; Amdt. 25-60, 51 FR 18243, May 16, 1986; Amdt. 25- 93, 63 FR 8048, Feb. 17, 1998]
b. Intent of Rule. This rule provides the standards for the various classes of transport category airplane cargo compartments. It does not cover closets and stowage compartments (See § 25.787). Cargo compartment liner standards and required flight tests to demonstrate compliance are addressed in § 25.855.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR) to replace part 4b of the Civil Air Regulations (CAR). The requirements in section 4b.383 of the CAR were carried over essentially unchanged to § 25.857 of 14 CFR.
(1) Amendment 25-32 (February 24, 1972) moved the liner requirements for Classes B through E to § 25.855.
(2) Amendment 25-60 (May 16, 1086) limited the volume of Class D compartments to a maximum of 1,000 cubic feet.
(3) Amendment 25-93 (February 17, 1998) revised paragraph (c)(2) to add reference to suppression systems as well as extinguishing systems, and eliminated reference to Class D compartments and reserved paragraph (d). Also see the explanation under § 25.855, Amendment
25-93.
(4) Harmonization. This regulation is the subject of a Federal Aviation Regulation/Joint Aviation Requirement (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group has provided the FAA with a fully harmonized draft notice of proposed rulemaking (NPRM) and an accompanying draft proposed advisory circular (AC) for regulatory evaluation. The NPRM and the AC provide the criteria for corrective action(s) that, if implemented, would be acceptable to the FAA for showing compliance with the airworthiness directive AD 93-07-15, or any new "combi" designs for Class B or the new proposed Class F cargo compartments. The NPRM proposes to revise §§ 25.855 and 25.857, and the proposed AC provides one means but not the only means of 102
compliance. Should an applicant not desire to comply with the requirements for Class B or class F compartments as stipulated above, then the main deck cargo compartments should comply with requirements for a Class C compartment as defined in current §§ 25.855 and 25.857.
d. Policy/Compliance Methods. For guidance on compliance with this requirement, refer to the preambles of this rule and the following information.
(1) Main Deck Cargo Compartment Fire Protection Certification Procedures. The following policy is extracted from an FAA letter dated June 6, 1997, and addresses requirements for “combi” airplanes. The letter is in response to a request from an applicant for information regarding certification of “combi” airplanes. The FAA refers to airplanes that can carry both passengers and cargo on the main deck as "combi's." The guidance is based on proposed rulemaking and advisory material being developed through the ARAC process.
(a) Information was requested concerning Federal Aviation Administration (FAA) requirements for certification of “combi” airplanes. The minimum design requirements for issuance of a Type Certificate for large transport airplanes are identified in 14 CFR part 25. The FAA was specifically asked to identify the criteria against which the FAA would evaluate the main deck fire protection features for FAA certification.
(b) The passenger and cargo compartments are separated by a partition that is either fixed or movable to accommodate various passenger/cargo combinations. Some “combi’s” can also accommodate all passenger or all cargo configurations. In most cases, the main deck cargo compartments on these airplanes are identified as Class B cargo compartments, which meet the fire protection requirements specified in § 25.857(b). Class B cargo compartments rely on manual firefighting as the primary method of controlling fires.
(c) In 1987, a South African Airways 747-200 “combi” crashed in the Indian Ocean following a fire in it’s main deck Class B cargo compartment. Following the investigation, the FAA concluded that manual firefighting in large Class B cargo compartments was not effective, and that the certification requirements identified in § 25.857(b) were inadequate. As a result, the FAA issued Airworthiness Directive (AD) 93-07-15, which required operators of existing large “combi” airplanes manufactured by Boeing or McDonnell Douglas to make significant modifications to their airplanes and operations. Operators were offered four options: (1) convert the Class B cargo compartment to Class C, (2) carry all cargo in the Class B cargo compartment in containers that meet the requirements for Class C cargo compartments,
(3) use fire containment covers or containers for all main deck cargo, along with other airplane and operational changes, or (4) incorporate a 90 minute duration fire suppression system, along with other airplane and operational changes.
(d) To address new “combi” designs, the FAA, through the Aviation Rulemaking Advisory Committee (ARAC) process, is proposing a revision to §§ 25.855 and 25.857 which would require Class B cargo compartments to be small enough that a crewmember with a hand held fire extinguisher can extinguish a fire anywhere within the compartment without entering it.
The FAA is also proposing a new cargo compartment classification, Class F. The proposed 103
Class F compartment would not be size-limited, and would require incorporation of a means to extinguish or control the fire without the need for a crewmember to enter the compartment. This includes not reaching in to move something in order to have full access to the fire extinguisher.
(e) The FAA has identified the criteria against which the FAA would evaluate main deck fire protection features on new “combi’s.” Although AD 93-07-15 provides an adequate level of safety for existing airplanes, the FAA recommends that all new “combi’s” meet the intent of the proposed changes to §§ 25.855 and 25.857. In addition, the effectiveness of the third and fourth options of AD 93-07-15 depends heavily on the FAA-monitored procedures, maintenance, and training at individual airlines, whereas the proposed part 25 changes rely on the airplane design, rather than airline operations. The FAA recognizes that the limited size of the proposed Class B cargo compartment would not meet operational needs. The FAA recommends that the main deck cargo compartment on the “combi” meet either the requirements for Class C cargo compartments identified in §§ 25.855 and 25.857, or the proposed requirements for Class F cargo compartments. The FAA and the ARAC are proposing that Class F cargo compartments meet the general cargo compartment requirements of § 25.855, and the following:
1 A Class F cargo compartment must have a liner that is separate from, but may be attached to, the airplane structure, unless it can be shown that other means for containing the fire and protecting critical systems and structure are provided.
2 The ceiling and sidewall panels of the liner in the Class F cargo compartment, if required, must meet the test requirements of part 25, Appendix F, part III, or other FAA-approved equivalent methods. This includes windows and window shades/covers in combi airplanes.
3 A means to extinguish or control the fire in the Class F cargo compartment, without requiring a crewmember to enter the compartment, must be provided.
4 A means to prevent hazardous amounts of smoke, flames, or suppression agent in the Class F cargo compartment from entering any occupied compartment must be provided.
5 A separate, FAA-approved smoke or fire detector system to alert the pilot or flight engineer station in the event of a fire must be provided.
(2) Class A Cargo Compartments: The following policy is extracted from an FAA memorandum dated February 8, 1996, to provide FAA policy regarding certification of passenger airplanes converted to all-cargo Class A or unclassified cargo compartment configurations.
(a) The FAA Transport Airplane Directorate has become aware of a number of transport category airplanes that have been reconfigured as all-cargo airplanes with cargo 104
compartments classified as Class A, or with the cargo compartment classification not addressed at all.
(b) An FAA memorandum , dated September 13, 1988, states that " . . . the agency policy has always been, and still is, that cargo compartments larger than that stated in Order 8110.27A(5)(b) are to be classified as Class B through E, whichever is applicable, and that operators comply with all requirements relative to each class." The aforementioned order describes the Class A compartment as " . . . small open compartments used for storage of crew luggage and located in the cockpit area where a fire can be easily discovered by a crewmember."
The order goes on to state that: "During the 74/75 Airworthiness Review, it was mentioned that full cabins or other large cargo compartments were presented for approval under Class A category, and that these compartments were consistently rejected on the basis that their volume was outside the intent of the Class A category where a fire must be rapidly detected and extinguished. Since the Class A compartment has no liner, large cargo areas have been considered to be outside the intent of the Class A category. It was recommended to limit the volume to 200 cubic feet."
(c) Advisory Circular (AC) 25-18, issued January 6, 1994, Transport Category Airplanes Modified for Cargo Service, addresses this subject. In the AC, Class A compartments are defined as follows:
1 "A Class A compartment is one that is located so close to the station of a crewmember that the crewmember would discover the presence of a fire immediately. In addition, each part of the compartment is easily accessible so that the crewmember could quickly extinguish a fire with a portable fire extinguisher. A Class A compartment is not required to have a liner.
2 "Typically, a Class A compartment is a small open compartment in the cockpit area used for storage of crew luggage. A Class A compartment is not, however, limited to such use; it may be located in the passenger cabin and used for other purposes provided it is close to a crewmember's station. Typically, the crewmember would be a member of the flightcrew; however, the compartment could be located adjacent to the station of any other crewmember.
3 "Because a Class A compartment does not have a liner, it is absolutely essential that the compartment be small and located close enough to a crewmember that any fire that might occur could be discovered and extinguished immediately. Without a liner to contain it, an undetected or uncontrolled fire could quickly become catastrophic by burning out of the compartment and spreading throughout the airplane. There is no specific limit on the volume;
however, all portions of the compartment must be virtually within arms length of the crewmember in order for any fire to be detected immediately and extinguished in a timely manner. Although there may be some exceptions, such as a 'U-Shaped' compartment for example, a Class A compartment greater than 50 cubic feet in volume would not typically have the accessibility required by § 25.857(a)(2) for fighting a fire."