Lavatory Fire Extinguisher Test Standard (LAVEX)
The requirement for an automatic fire extinguisher which discharges into a lavatory trash container was proposed in FAA Notice 84-5 as a consequence of two incidents. The first involved an aircraft cabin fire (Air Canada, Cincinnati 1983) in which 23 people perished. The second occurred at Tampa International Airport in Florida on June 25, 1983 that resulted in evacuation of the aircraft with no injuries or loss of life. Following these accidents, an inspection survey of the U.S. carrier fleet by the FAA revealed that the fire containment capabilities of trash containers may be compromised by the wear and tear typical of service. Considering the seriousness of in-flight cabin fires, enhanced fire protection was considered necessary. As a result, rulemaking was implemented on April 29, 1987, that required each lavatory trash container be equipped with a built-in automatic fire extinguisher which discharges automatically into the container upon the occurrence of a fire.
Previously, all aircraft lavatory disposal receptacle fire extinguishers use Halon 1301 as the fire extinguishing agent. To establish that a replacement agent provides an equivalent level of safety to that of Halon 1301, the performance is measured against a standard test method. The FAA established the International Halon Replacement Working Group to address the development of performance standards for aircraft fire extinguishing systems employing halons. A specific Task Group was formed to develop a minimum performance standard for the lavatory trash receptacle fire extinguishing system. The minimum performance standard development process started with the test article, shown in figure 1, based on input from the Boeing Commercial Airplane Group. The test article is considered to be representative of the largest trash receptacle in current service. Ventilation is provided at both the top and bottom of the test article to allow sufficient circulation of air for combustion to start and sustain until the lavatory extinguisher (Lavex) discharges. The ventilation holes were provided with damper flaps that can be closed upon discharge initiation to minimize leakage of the agent from the bottom of the test article.
Based on numerous initial tests, crumpled paper hand towels was established as the most appropriate fire load. A pair of nichrome coils located close to the bottom of the trash receptacle comprises the ignition source. The intention is to simulate a glowing cigarette buried in the trash, resulting in deep-seated, smoldering combustion. In order to cover the range of aircraft operational conditions, a minimum test temperature was established to ensure proper functioning of the Lavex in cold climates, which can result when an aircraft is parked for extended periods. Several other requirements were implemented into the minimum performance standard in order to obtain a repeatable test condition. These include: standardization of the ignition source temperature, towel specification, a minimum number of required successful tests for acceptance, and tolerances on the actual "crumpling" tightness of the paper towels. The minimum performance standard development chronology is documented in FAA Report, "Development of a Minimum Performance Standard for Lavatory Trash Receptacle Automatic Fire Extinguishers, DOT/FAA/AR-96/122", dated February 1997. You may view this report from the Reports page of this website. The aforementioned test standard may be used in certification testing of alternative agents to halon for lavatory trash receptacles. Policy Letter TAD-97-003, March 31, 1997 generated by the FAA Transport Airplane Directorate, was circulated to the various Aircraft Certification Offices to serve notice that this new standard is now in place.
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