573 SECTION 25.857 CARGO COMPARTMENT CLASSIFICATION
671. REGULATION IN EFFECT AT ADOPTION OF PART 25.
a. Regulation.
(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; and
(4) There is a fire-resistant lining.
(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 system controllable from the pilot or flight engineer stations;
(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; and
(5) There is a fire-resistant lining.
(d) Class D. A Class D cargo or baggage compartment is one in which-
(1) A fire occurring in it will be completely confined without endangering the safety of the airplane or the occupants;
(2) There are means to exclude hazardous quantities of smoke, flames, or other noxious gases, from any compartment occupied by the crew or passengers;
(3) Ventilation and drafts are controlled within each compartment so that any fire likely to occur in the compartment will not progress beyond safe limits;
(4) There is a fire-resistant lining; and
(5) Consideration is given to the effect of heat within the compartment on adjacent critical parts of the airplane.
For compartments of 500 cubic feet or less, an airflow of 1500 cubic feet per hour is acceptable.
(e) Class E. A Class E cargo compartment is one on airplanes used only for the carriage of cargo and in which-
(1) There is a fire-resistant lining;
(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 flightcrew in the crew compartment;
(4) There are means to exclude hazardous quantities of smoke, flames, or noxious gases, from the flightcrew compartment; and
(5) The required crew emergency exits are accessible under any cargo loading condition.
b. Guidance.
(1) Paragraphs (a), (b), and (c). In the interest of fire protection, classification of cargo compartments on transport category airplanes was developed and incorporated into a rule with CAR Amendment 04-1 on November 1, 1946. Class A, B, and C categories were established, and two basic factors of fire protection were envisioned: (Amendment 25-0)
(i) Detection of a fire by a crewmember while at his station. (Amendment 25-0)
(ii) Extinguishment or suppression of the fire when detected. (Amendment 25-0)
(2) Paragraphs (d) and (e). Later, a Class D compartment was developed and incorporated into a rule with CAR Amendment 4b-6 on July 20, 1950. Further, when a need developed for bulk loading cargo into the main cabin in which the fire protection provision of the Class A, B, C, and D did not suffice, a Class E category was established. The Class E was incorporated into a rule with CAR Amendment 4b-10 on April 23, 1959. The basic category provisions are essentially the same to date in current part 25 requirements. The main differences in classification are: (Amendment 25-0)
(i) Accessibility. (Amendment 25-0)
(ii) Means of detection of fire or smoke. (Amendment 25-0)
(iii) Method of extinguishment or suppression of fire. (Amendment 25-0)
(iv) Protection for structural members. (Amendment 25-0)
(3) Paragraphs (a), (b), (c), (d) and (e). As prescribed in CAR 4b and part 25, the Class A requires that the presence of a fire be readily discernible to a crewmember at his station and that all parts be easily accessible. The Class B must also be accessible, but detection is by smoke/fire detectors. The Class C, D, and E are generally not accessible and detection in the C and E are by smoke/fire detectors. Extinguishment in the Class C is by flooding, in the Class D by suppressing oxygen, and in the Class E by shutting off the ventilating airflow. Fire resistant liners were required in the Class B, C, D, and E for protection of structural members.
(Amendment 25-0)
(4) Paragraphs (a), (d), and (e). With the exception of the Class D, which is limited to 2000 cubic feet, and the Class E, which was designed to encompass the entire passenger cabin, no specific volume limits were prescribed for the other category compartments. Early regional guidance, however, envisioned the Class A compartment as a small open container for storage of crew luggage located in the pilot compartment where the presence of any fire could be rapidly detected by the crew. Refer to the guidance in paragraph 672.b.(2) below. (Amendment 25-0)
(5) Paragraph (b)(1). In order to demonstrate that any part of the compartment can be effectively reached, the following test may be conducted: (Amendment 25-0)
(i) The test may be conducted in an airplane sitting statically on the ground. The cargo compartment should be filled to that allowed by the type design with empty cardboard boxes and such as mailbags filled with crumpled newspapers. (Amendment 25-0)
(ii) The assigned flight crewmember should be seated at his station with his seat belt and shoulder harness engaged. (Amendment 25-0)
(iii) When the test begins, the crewmember should don the portable oxygen equipment, carry the fire extinguisher to the most remote part of the cargo compartment and
576 remove the necessary boxes and bags in order to touch the pre-assigned and/or identified most remote box or bag with his hand. This ends the test. (Amendment 25-0)
(iv) The test time should be no longer than 5 minutes. (Amendment 25-0)
(6) Paragraphs (b)(3), (c)(1) and (e)(2). An acceptable detection time for smoke detectors is 5 minutes. Use the smoke quantity and location criteria of AC 25-9A, “Smoke Detection, Penetration, and Evacuation Tests, and Related Flight Manual Emergency Procedures,” dated 1/6/94, for showing that the smoke detection system detects a fire in satisfactory time. The time for fire detection systems was changed to one minute by Amendment 25-54 in § 25.858. (Amendment 25-0)
(7) Paragraphs (b)(4), (c)(5), (d)(4), and (e)(1). Refer to paragraph 621b(2) for an acceptable test for fire resistance. (Amendment 25-0)
(8) Paragraphs (b), (c), (d), and (e). Refer to AC 25-9A, “Smoke Detection, Penetration, and Evacuation Test, and Related Flight Manual Emergency Procedures,” dated 1/6/94. (Amendment 25-0)
(9) Paragraphs (b), (c), (d), and (e). The lining discussed in the Class B, C, D, and E, compartments refers to the sidewalls, ceilings and forward and aft panels of the compartments.
(Amendment 25-0)
672. AMENDMENT 25-32, Effective May 1, 1972.
a. Regulation.
(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; and
577 [(4) [Reserved.]]
(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 system controllable from the pilot or flight engineer stations;
(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; and [(5) [Reserved.]]
(d) Class D. A Class D cargo or baggage compartment is one in which-
(1) A fire occurring in it will be completely confined without endangering the safety of the airplane or the occupants;
(2) There are means to exclude hazardous quantities of smoke, flames, or other noxious gases, from any compartment occupied by the crew or passengers;
(3) Ventilation and drafts are controlled within each compartment so that any fire likely to occur in the compartment will not progress beyond safe limits;
[(4 ) [Reserved.]]
(5) Consideration is given to the effect of heat within the compartment on adjacent critical parts of the airplane.
For compartments of 500 cu. ft. or less, an airflow of 1500 cu. ft. per hour is acceptable.
(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 exists are accessible under any cargo loading condition.
b. Guidance.
(1) Paragraphs (b), (c), (d) and (e). When the liner requirements were transferred to § 25.855, in addition to being fire resistant, the liner also had to meet the flammability requirements of § 25.853(b). (Amendment 25-32)
(2) Paragraphs (a), (b), (c), (d) and (e). Guidance material was developed to assure that approvals of cargo compartments would meet the intent of the rule and DOT/FAA Order 8110.27A, CAR 4b.383 and CFR 25.855 and 25.857, “Cargo Compartment Classification Requirements,” was written for that purpose in 1978. The order is pertinent to all certificated airplanes engaged in cargo operations and previous approvals not commensurate with the order will not be accepted as precedent. The following is based on the procedures from that order:
(Amendment 25-32)
(i) Class A. A compartment in which the presence of a fire would be easily discovered by a crewmember while at his station, all parts of which are easily accessible in flight. This is typically a small compartment used for crew luggage and located in the cockpit where a fire would be readily detected and extinguished by a crewmember. Due to the small size and location of the compartment, and the relatively brief time required to extinguish a fire, a liner is not needed to protect adjacent structure. (Amendment 25-32)
(ii) Class B. A compartment with sufficient access in flight to enable a crewmember to effectively reach any part of the compartment with the contents of a hand held fire extinguisher and that incorporates a separate, approved smoke or fire detection system to give warning at the pilot or flight engineer station. A Class B compartment is typically much larger than a Class A compartment and can be located in an area remote from the cockpit.
Because of the larger size of the compartment and the greater time interval likely to occur before a fire would be controlled, a liner meeting the flame penetration standards of § 25.855 and Appendix F of part 25 must be provided to protect adjacent structure. (Amendment 25-32)
(iii) Class C. As defined at the time of initial classification, any compartment that did not fall into either Class A or B was a Class C compartment. Class C compartments differ from Class B compartments primarily in that built-in extinguishment systems are provided for control of fires in lieu of crewmember accessibility. (Amendment 25-32)
(iv) Later, two additional classes were established and defined as follows:
(Amendment 25-32) (A) Class D. A compartment in which a fire would be completely contained without endangering the safety of the airplane or the occupants. A Class D compartment is similar to a Class C compartment in that both are typically large and located in areas that are not readily accessible to a crewmember. In lieu of providing fire detection and extinguishment, Class D compartments are designed to control a fire by severely restricting the supply of available oxygen. Because an oxygen deprived fire might continue to smolder for the duration of the flight, the capability of the liner to resist flame penetration is especially important.
(Amendment 25-32) (B) Class E. The main cargo compartment of an airplane used only for the carriage of cargo. A fire in a Class E compartment is controlled through crew action to shut off the ventilating air flow. Like that of a Class D compartment, the capability of the liner to resist flame penetration is especially important. (Amendment 25-32)
(v) Liner materials must currently meet the same flame penetration standards regardless of the class of compartment in which they are used. (Amendment 25-32)
(vi) No specific volume limits were established for the various classes of compartments although, as noted above, Class A compartments were envisioned as small, open compartments located in the cockpit area. In addition, the compartment volume and leakage rate are factors that must be considered in determining compliance with the objective requirements of part 25 for Class D compartments. The sum of the volume of a Class D compartment and the volume of leakage from the compartment experienced in one hour should not exceed 2,000 cubic feet. (Amendment 25-32)
(vii) A nonaccessible compartment located below the main cabin could be either a Class C or D compartment for passenger airplanes or Class C, D, or E for all cargo airplanes.
Cabin flooring utilized to protect adjacent structure from fire originating in a cargo or baggage compartment located above the floor should not also serve as the lining for a compartment located below the floor. (Amendment 25-32)
(3) Paragraphs (b)(3), (c)(1) and (e)(2). An acceptable detection time for smoke detectors is 5 minutes. Use the smoke quantity and location criteria of AC 25-9A, “Smoke Detection, Penetration, and Evacuation Tests, and Related Flight Manual Emergency Procedures,” dated 1/6/94, for showing that the smoke detection system detects a fire in satisfactory time. The time for fire detection systems was changed to one minute by Amendment 25-54 in § 25.858. (Amendment 25-0)
(4) Paragraphs (b), (c), (d), and (e). Refer to AC 25-9A, “Smoke Detection, Penetration, and Evacuation Test, and Related Flight Manual Emergency Procedures,” dated 1/6/94. (Amendment 25-0)
(5) Paragraphs (b), (c), (d), and (e). The lining discussed in the Class B, C, D, and E, compartments refers to the sidewalls, ceilings and forward and aft panels of the compartments.
(Amendment 25-0)
673. AMENDMENT 25-60, Effective June 16, 1986.
a. Regulation.
(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 cre member 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; and
(4) [Reserved.]
(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 system controllable from the pilot or flight engineer stations;
(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; and
(5) [Reserved]
(d) Class D. A Class D cargo or baggage compartment is one in which-
(1) A fire occurring in it will be completely confined without endangering the safety of the airplane or the occupants;
(2) There are means to exclude hazardous quantities of smoke, flames, or other noxious gases, from any compartment occupied by the crew or passengers.
(3) Ventilation and drafts are controlled within each compartment so that any fire likely to occur in the compartment will not progress beyond safe limits;
(4) [Reserved]
(5) Consideration is given to the effect of heat within the compartment on adjacent critical parts of the airplane.
[(6) The compartment volume does not exceed 1,000 cubic feet.] For compartments of 500 cu. ft. or less, an airflow of 1500 cu. ft. per hour is acceptable.
(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.
b. Guidance.
(1) Paragraphs (b), (c), (d) and (e). When the liner requirements were transferred to § 25.855, in addition to being fire resistant, the liner also had to meet the flammability requirements of § 25.853(b). (Amendment 25-32)
(2) Paragraphs (a), (b), (c), (d) and (e). Guidance material was developed to assure that approvals of cargo compartments would meet the intent of the rule and DOT/FAA Order 8110.27A, CAR 4b.383 and CFR 25.855 and 25.857, “Cargo Compartment Classification Requirements,” was written for that purpose in 1978. The order is pertinent to all certificated airplanes engaged in cargo operations and previous approvals not commensurate with the order will not be accepted as precedent. The following is based on the procedures from that order:
(Amendment 25-32)
(i) Class A. A compartment in which the presence of a fire would be easily discovered by a crewmember while at his station, all parts of which are easily accessible in flight. This is typically a small compartment used for crew luggage and located in the cockpit where a fire would be readily detected and extinguished by a crewmember. Due to the small size and location of the compartment, and the relatively brief time required to extinguish a fire, a liner is not needed to protect adjacent structure. (Amendment 25-32)
(ii) Class B. A compartment with sufficient access in flight to enable a crewmember to effectively reach any part of the compartment with the contents of a hand held fire extinguisher and that incorporates a separate, approved smoke or fire detection system to give warning at the pilot or flight engineer station. A Class B compartment is typically much larger than a Class A compartment and can be located in an area remote from the cockpit.
Because of the larger size of the compartment and the greater time interval likely to occur before a fire would be controlled, a liner meeting the flame penetration standards of § 25.855 and Appendix F of part 25 must be provided to protect adjacent structure. (Amendment 25-32)
(iii) Class C. As defined at the time of initial classification, any compartment that did not fall into either Class A or B was a Class C compartment. Class C compartments differ from Class B compartments primarily in that built-in extinguishment systems are provided for control of fires in lieu of crewmember accessibility. (Amendment 25-32)
(iv) Later, two additional classes were established and defined as follows:
(Amendment 25-32) (A) Class D. A compartment in which a fire would be completely contained without endangering the safety of the airplane or the occupants. A Class D compartment is similar to a Class C compartment in that both are typically large and located in areas that are not readily accessible to a crewmember. In lieu of providing fire detection and extinguishment, Class D compartments are designed to control a fire by severely restricting the supply of available oxygen. Because an oxygen deprived fire might continue to smolder for the duration of the flight, the capability of the liner to resist flame penetration is especially important.
(Amendment 25-32) (B) Class E. The main cargo compartment of an airplane used only for the carriage of cargo. A fire in a Class E compartment is controlled through crew action to shut off the ventilating air flow. Like that of a Class D compartment, the capability of the liner to resist flame penetration is especially important. (Amendment 25-32)
(v) Liner materials must currently meet the same flame penetration standards regardless of the class of compartment in which they are used. (Amendment 25-32)
(vi) No specific volume limits were established for the various classes of compartments although, as noted above, Class A compartments were envisioned as small, open compartments located in the cockpit area. In addition, the compartment volume and leakage rate are factors that must be considered in determining compliance with the objective requirements of part 25 for Class D compartments. The sum of the volume of a Class D compartment and the volume of leakage from the compartment experienced in one hour should not exceed 2,000 cubic feet. (Amendment 25-32)
(vii) A nonaccessible compartment located below the main cabin could be either a Class C or D compartment for passenger airplanes or Class C, D, or E for all cargo airplanes.
Cabin flooring utilized to protect adjacent structure from fire originating in a cargo or baggage compartment located above the floor should not also serve as the lining for a compartment located below the floor. (Amendment 25-32)
(3) Paragraphs (b)(3), (c)(1) and (e)(2). An acceptable detection time for smoke detectors is 5 minutes. Use the smoke quantity and location criteria of AC 25-9A, “Smoke Detection, Penetration, and Evacuation Tests, and Related Flight Manual Emergency Procedures,” dated 1/6/94, for showing that the smoke detection system detects a fire in satisfactory time. The time for fire detection systems was changed to one minute by Amendment 25-54 in § 25.858. (Amendment 25-0)
(4) Paragraphs (b), (c), (d), and (e). Refer to AC 25-9A, “Smoke Detection, Penetration, and Evacuation Test, and Related Flight Manual Emergency Procedures,” dated 1/6/94. (Amendment 25-0)
(5) Paragraphs (b), (c), (d), and (e). The lining discussed in the Class B, C, D, and E, compartments refers to the sidewalls, ceilings and forward and aft panels of the compartments.
(Amendment 25-0)
674. AMENDMENT 25-93, Effective March 19, 1998.
a. Regulation.
(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; and
(4) [Reserved.]
(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; and
(5) [Reserved.] [(d) [Reserved.]]
(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