A compre­hensive systems-level approach in cabin design minimizes fire potential and helps ensure safety.

18 aero quarterly qtr_04 | 11 Fire Protection: Passenger cabin

the cabins on all boeing airplanes incorporate comprehensive fire-protective features and materials to minimize the potential for a fire and help ensure the safety of .

By Arthur L. Tutson, boeing organization Designation authorization, authorized representative, Fire Protection; Douglas E. Ferguson, technical Safety chief, Fire Protection, technical Services and modifications; and Mike Madden, Deputy Pressurized compartment Fire marshal, Payloads Design

This article is the third in a series exploring approach that goes beyond ensuring this article describes how boeing the implementation of fire protection on individual parts meet fire property require- incorporates fire protection features and transport category airplanes. ments by looking at the integration of all materials into the airplane cabin that meet those parts on the airplane. this approach or exceed fire protection standards defined two types of fires can affect an airplane uses the principles of material selection, by u.S. Federal aviation regulations (Far). and its occupants: in-flight and post-crash. separation, isolation, detection, and control. an in-flight fire usually occurs as a result of these principles involve separating the a system or component failure or mainte- FirE-proTEcTivE MATEriALs three contributory factors to a fire (fuel, nance issue. a post-crash fire usually ignition source, and oxygen), isolating results from ignition of fuel released during most materials used in the construction potential fires from spreading to other parts a crash landing. boeing considers both of passenger compartment interiors are of the airplane, and controlling a fire should types of fires when designing for airplane required by the u.S. Federal aviation one occur. boeing uses both passive sys- cabin fire protection. Fire protection is one administration (Faa) to be self-extinguishing tems (such as the use of noncombustible of the highest considerations at boeing in (i.e., stop burning after the flame source or self-extinguishing materials) and active airplane design, testing, and certification. has been removed) or better. For example, systems (such as fire extinguishing systems). in designing an airplane’s fire protection electrical wire and cable insulation must be Fire protection features on boeing airplanes features, boeing uses a systems-level self-extinguishing. meet all aviation regulatory requirements as

well as internal boeing design requirements. 19 WWW.boeing.com/commercial/aeromagazine Figure 1: insulation blanket burn-through protection Fire-protective insulation blankets are designed to resist burn-through from a fuel fire next to the bottom half of the fuselage.

1 Halfway Line 1 3 2 Windows 3 Insulation 4 Steel Clip 2 2 2 2 2 2 5 Tape 6 Overframe Blanket 7 Between-Frame Blanket

View looking outboard

4 5 4 5

6

7

View looking down

interior components of boeing airplanes contribution of the insulation blankets to ■ establish design features to minimize meet flammability requirements prescribed the propagation of a fire. thermal/acoustic potential ignitions. in title 14 code of Federal regulations insulation installed behind cabin interior ■ establish design features to isolate poten- (cFr) Part 25. these components include: panels with the appropriate fire-resistant tial ignition sources from combus tibles properties can delay the onset of fire into the (e.g., electrical shutoff switches for ■■ interior ceiling. cabin in the event of a crash (see fig. 1). in-flight entertainment systems). ■■ interior sidewall panels. the insulation blankets, along with the ■ establish design features to contain or ■■ Partitions. airplane skin, must be capable of resisting localize potential fires, including arrange- ■■ surfaces and structure. burn-through from a fuel-fed post-crash ment, materials, and ventilation. examples ■■ exposed surfaces of stowed galley fire next to the bottom half of the fuselage include galley trash compartments, fire carts and standard galley containers. for a minimum of four minutes to allow stops behind monuments, and sidewalls. ■■ large cabinets and cabin stowage passen gers to evacuate the airplane before compartments. burn-through can occur. ■■ Passenger seat material. FirE DETEcTion

For materials in areas not covered by the isoLATion AnD sEpArATion three types of smoke detectors are cFr requirements, boeing design guidelines conTroLs certified for use in the lavatories and crew are used to identify additional flammability, rest compartments, as well as in some smoke, and toxicity requirements. boeing reviews the overall design of the galley complexes, work stations, the standards for flammability of insu- airplane at a systems level to further video control centers, and business lation blankets have improved over time. enhance airplane safety. this includes centers: ionization-area type, photoelectric- a recent requirement change calls for the the following based on established boeing area type, and photoelectric-ducted type. enhancement of the fire-protective features design guidelines: a dedicated smoke detection system is not of insulation blankets in the event of an required in the occupied volumes of the in-flight or post-crash fire. the latest stan- ■ identify potential ignition sources. main cabin due to the ability of passengers dard increases protection by minimizing the ■ identify failure modes to ensure ignition and the cabin crew to recognize smoke. sources are minimized.

20 aero quarterly qtr_04 | 11 Figure 2: ceiling-mounted smoke detectors Typical faceplate of a ceiling-mounted ionization smoke detector (left) and a photoelectric smoke detector (right).

Ionization smoke detector Photoelectric smoke detector

ionization-area type. these detectors are Photoelectric-ducted type. these detectors conTroL oF FirEs designed to detect the presence of ionized are similar to photoelectric-area type particles created by the combustion process detectors, but they are typically mounted Handheld fire extinguishers are provided as they are convectively carried through behind the walls of the protected space. throughout the airplane cabin for manual the lavatories or crew rest compartments they differ from the area detectors in that firefighting. boeing airplanes currently use in the event of a fire. they are typically fans draw air samples from the protected water or Halon 1211 fire extinguishers. mounted in the ceiling or upper sidewalls space into a series of air sampling ports in boeing is working on a replacement for of the protected space (see fig. 2). the monument walls and ceiling, and then halon extinguishers, but it is not yet through an aluminum tube manifold to available. (For an in-depth discussion Photoelectric-area type. these detectors the detectors. current production airplanes on halon, see page 13.) are designed to detect the presence of use the more advanced area detectors Halon 1211 fire extinguishers have a smoke particles in the air by reflection mentioned above, rather than ducted minimum underwriters laboratories rating of scattered light. they also rely on photoelectric detectors. of 5b:c. this type of extinguisher contains particles in the air being convectively each smoke detection system has a approximately 2.5 pounds (1 kilogram) of carried into a sensing chamber where built-in electronic test capability switch. this Halon 1211, weighs about 4 pounds (1.8 kilo- light from a pilot lamp is transmitted allows for the system’s electrical and detector grams), and can be used on any fire likely to through a sensing chamber. if smoke is sensor integrity to be checked at any time. occur in the airplane, including paper, fabric, present, it will reflect light onto a photocell Detection of smoke is affected by electrical, or flammable fluids. Halon 1211 and trigger an alarm. newer production compartment volume and contour, air extinguishers have also been successful in airplanes use photoelectric detectors based distribution, and the amount and buoyancy extinguishing fires behind the sidewall panels. on an advanced smoke sensor utilizing of the combustion particles. boeing con- Water fire extinguishers have Faa two discrete wavelengths to determine ducts extensive laboratory and flight testing technical standard order (tSo)-c19c the presence of smoke and to distinguish to determine the best location for the certification approval. these units are between smoke and nonsmoke aerosols. detector sensors to enable them to most intended to com bat fires involving combus- these are also mounted in the ceiling or effectively detect smoke under all conditions. tible materials such as paper and textiles. upper sidewalls of the protected space.

21 WWW.boeing.com/commercial/aeromagazine Figure 3: Typical fire extinguisher locations Fire extinguishers are located throughout the passenger cabin with locations designed for easy access in an emergency.

Halon Water Water For lavatory fire Halon extinguishers, see figure 5.

Halon Halon Halon Halon

Fire Extinguisher ■■ Halon [6] ■■ Water [2]

Figure 4: Distribution of handheld Halon 1211 or equivalent fire extin- crew/attendant rest compartments, purser fire extinguishers guishers are spaced throughout the cabin work stations, video control centers, and the number of handheld fire extinguishers and easily accessible from the aisle or business centers. at least one Halon 1211 on passenger airplanes is determined by entryway. a water fire extinguisher is or equivalent fire extinguisher is generally the airplane’s passenger capacity. typically located near a lavatory-galley located within 8 feet (2.4 meters) of the complex. in some cases, one or more compartment. Halon 1211 extinguishers are used in airplane lavatories. each lavatory is equipped number of place of the water fire extinguisher. Passenger extinguishers with fire protection systems designed to capacity detect and extinguish fires and to prevent FirE ExTinguishEr LocATions hazardous quantities of smoke from 61–200 3 entering occupied areas (see fig. 5). both halon and water fire extinguishers are lavatory fire-protection features include: located throughout the passenger cabin (i.e., 201–300 4 ■■ a smoke detection system that provides each passenger compartment sepa rated a warning light on the flight deck, or pro- by doors or stairways) (see fig. 3). the mini- vides a warning light or audible warning 301–400 5 mum number of extinguishers is based on in the passenger cabin that would be the airplane’s passenger capacity (see fig. 4). readily detected by a . 401–500 6 galley complex. a Halon 1211 or equivalent ■■ each receptacle used for the disposal fire extinguisher is generally located within of flammable waste material is fully 8 feet (2.4 meters) of each galley complex. enclosed, constructed of fire-resistant 501–600 7 materials, and able to contain fires Flight deck. a Halon 1211 or equivalent that might occur. extinguisher is placed for easy access by 601–700 8 ■■ boeing requires that all current the flight crew. production lavatories be capable of containing a fire for 30 minutes.

22 aero quarterly qtr_04 | 11 Figure 5: Lavatory fire protection Lavatories include systems to both detect and extinguish fires.

Fire Extinguisher

Waste Smoke Detector Flap

Cold Air Inlet Waste Chute Waste Flap

Fusible Tip

Note: Installation of the items shown varies by airplane model.

■■ a built-in fire extinguisher for each paper . a smoke detec- Firefighting procedures for crew rest waste disposal receptacle located within tion system that consists of ceiling- and/or compartments usually involve one or more the lavatory. the extinguisher is designed sidewall-mounted smoke detectors and members of the cabin crew using appro- to discharge automatically into each associated control hardware and alarms is priate protective equipment to manually disposal receptacle upon occurrence of incorporated into crew rest compartments. suppress the fire with a handheld fire a fire in that receptacle. all boeing lava- crew rest compartments are also designed extinguisher. in some cases, such as the tories incorporated the use of Halon 1301 to prevent hazardous quantities of smoke 777 lower lobe attendant rest compart- as the suppression agent in fire extin- from entering flight crew or passenger areas. ment, the fire is suppressed remotely by guish ers. on boeing production airplanes, When smoke is detected by the smoke using a built-in halon fire-extinguishing beginning with the 777 in april 2006, these detection system, appropriate audio and system plumbed to the compartment. extinguishers were replaced with Fm-200 visual alarms provide indication on the (HFc-227ea). all built-in fire extinguishers flight deck, in the crew rest compartment, suMMAry meet these Faa requirements: and in the nearby cabin areas. For larger no extinguishing agent that is likely to crew rest compartments, the air distribution boeing uses a comprehensive systems- enter personnel compartments can system’s air shutoff valve closes, preventing level approach in airplane cabin design to be hazardous to the occupants. air-conditioning flow to the crew rest com- minimize the potential for a fire and to help no discharge of the extinguisher can partment to better contain smoke and ensure the safety of passengers. cause structural damage. facilitate crew firefighting procedures. in For more information, please contact art the capacity of each extinguishing many instances, a minimal exhaust flow is tutson at [email protected]. system must be adequate for any fire maintained to assist in preventing smoke likely to occur in the compartment penetration into occupied areas and main- where used, considering the volume tain visibility. of the compartment and the ventila- tion rate.

23 WWW.boeing.com/commercial/aeromagazine