Halon replacement deadlinesIn 2010, the European Commission adopted cutoff and end dates for essential-use exemptions for halon on airplanes operating in the European Union. The International Civil Aviation Organization adopted halon replacement deadlines in 2011, and Underwriters Laboratories will withdraw its standard for halon in handheld fire extinguishers in 2014.Aggressively Pursue Aggressively pursuing a fire means taking immediate action todetermine the source of hot spots, smoke, and/or flames. The crew should quickly evaluate thesituation, gain access to the fire, and attack the fire using all available resources, which mayinclude deadheading crewmembers or able-bodied persons (ABP).Cheek AreaThis term describes the area just below the floor, outboard of the cargocompartment areas. In narrow and widebody aircraft, this area houses wire bundles, hydrauliclines, and other electrical components. (See Appendix 2, Typical Widebody Cross-Section.)c. Circuit Breaker. Circuit breakers are designed to open an electrical circuit automaticallyat a predetermined overload of current.d. Halon Halon is a liquefied gas that extinguishes fires by chemically interrupting a firescombustion chain reaction, rather than physically smothering it. This characteristic is one of themain reasons that halon extinguishers are effective when the exact source of the fire cannot bepositively determined. Halon fire extinguishing agents that have been approved for use in aircraftinclude Halon 1211, Halon 1301, and a combination of the two (Halon 1211/1301). Both aretypified as clean agents, leaving no agent residue after discharge. Approved halon-typeextinguishers are three times as effective as carbon dioxide (CO2) extinguishers with the sameweight of extinguishing agent.Insulation blanket burn-through protectionFire-protective insulation blankets are designed to resist burn-through from a fuel fire next to the bottom half of the fuselagePhotoelectric-area type. These detectors are designed to detect the presence of smoke particles in the air by reflection of scattered light. They also rely on particles in the air being convectively carried into a sensing chamber where light from a pilot lamp is transmitted through a sensing chamber. If smoke is present, it will reflect light onto a photocell and trigger an alarm. Newer production airplanes use photoelectric detectors based on an advanced smoke sensor utilizing two discrete wavelengths to determine the presence of smoke and to distinguish between smoke and nonsmoke aerosols. These are also mounted in the ceiling or upper sidewalls of the protected space.Photoelectric-ducted type. These detectors are similar to photoelectric-area type detectors, but they are typically mounted behind the walls of the protected space. They differ from the area detectors in that fans draw air samples from the protected space into a series of air sampling ports in the monument walls and ceiling, and then through an aluminum tube manifold to the detectors. Current production airplanes use the more advanced area detectors mentioned above, rather than ducted photoelectric detectors.Each smoke detection system has a built-in electronic test capability switch. This allows for the systems electrical and detector sensor integrity to be checked at any time.Detection of smoke is affected by compartment volume and contour, air distribution, and the amount and buoyancy of the combustion particles. Boeing conducts extensive laboratory and flight testing to determine the best location for the detector sensors to enable them