1
Introduction

STATEMENT OF THE PROBLEM

The Aviation Safety Research Act of 1988 (P. L. 100-591) was aimed at improving air travel safety in the United States. The details of this legislation and related legislation (Federal Aviation Act of 1958, Aircraft Catastrophic Failure Prevention Research Act of 1990) are summarized in Appendix B.

The Aviation Safety Research Act of 1988 directed the Federal Aviation Administration (FAA) to spend at least 15 percent of its research budget on long-term investigations concerned with:

  • aviation maintenance (addresses the aging fleet),

  • fire safety (addresses fire containment and the fire resistance of engine fuel and cabin materials),

  • human factors (addresses performance of flight crew, aircraft mechanics, and air traffic controllers), and

  • dynamic simulation modeling of the air traffic control system (addresses air traffic capacity and control).

Following the Act's directive that, as part of fire-safety research, "The [FAA] Administrator shall undertake or supervise research to develop technologies and to conduct data analyses...to assess the fire and smoke resistance of aircraft materials..." the FAA Technical Center established a research program in advanced fire-safe materials and enumerated its goals in a high-level materials research and development plan (Lyon and Eklund, 1993), and also created a preliminary detailed plan for the work (Lyon, 1994). The FAA plans and goals for fire-resistant materials research are summarized in Appendix B.

According to the program plan, the objective of the program is to

discover the fundamental relationships between the composition and structure of materials and their behavior in fires to enable the design of a totally fire-resistant cabin for future commercial aircraft. Research will be basic in nature and will focus on synthesis, characterization, modeling, and processing of new materials and materials combinations to improve the fire performance, increase the functionality, and reduce the cost of next-generation cabin materials.

The FAA Technical Center began acquiring staff and laboratory equipment for this program in 1993. The program is envisioned to be a long-range effort to develop fire-safe materials for use on future commercial aircraft that would represent an "order-of-magnitude" improvement in aircraft cabin fire-worthiness. The program has the following goals:

  • determine the fundamental relationships between the composition and structure of materials and their behavior in fires,

  • use this knowledge to identify and design new materials and material combinations that provide an order-of-magnitude improvement in fire-worthiness, and

  • develop the processing technology to ensure manufacturability and recyclability of advanced fire-safe materials.

To provide guidance for this effort, the FAA requested that the National Research Council (NRC), through its National Materials Advisory Board, establish a committee to identify promising fire-resistant1 materials technologies, component design issues, and performance parameters and to recommend research in promising areas. To carry out its charge, the NRC committee held a technical conference at which the participants assessed the state of the an of fire-resistant materials, reviewed ongoing research in improved materials, summarized significant findings, and suggested objectives for the FAA advanced fire-safe materials research program. Included in the published conference proceedings (NRC, 1995) are the conference workshop session summaries upon which the committee built its evaluation to arrive at its final conclusions and recommendations for this report.

ACCIDENT STATISTICS

In the development of their research initiatives, the FAA based much of its planning on how to counter the kinds of accidents that have occurred in the past. Aircraft accident

1  

Fire resistance is defined as the property of a materials or assemblage to withstand fire or give protection from it (ASTM, 1994).



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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft 1 Introduction STATEMENT OF THE PROBLEM The Aviation Safety Research Act of 1988 (P. L. 100-591) was aimed at improving air travel safety in the United States. The details of this legislation and related legislation (Federal Aviation Act of 1958, Aircraft Catastrophic Failure Prevention Research Act of 1990) are summarized in Appendix B. The Aviation Safety Research Act of 1988 directed the Federal Aviation Administration (FAA) to spend at least 15 percent of its research budget on long-term investigations concerned with: aviation maintenance (addresses the aging fleet), fire safety (addresses fire containment and the fire resistance of engine fuel and cabin materials), human factors (addresses performance of flight crew, aircraft mechanics, and air traffic controllers), and dynamic simulation modeling of the air traffic control system (addresses air traffic capacity and control). Following the Act's directive that, as part of fire-safety research, "The [FAA] Administrator shall undertake or supervise research to develop technologies and to conduct data analyses...to assess the fire and smoke resistance of aircraft materials..." the FAA Technical Center established a research program in advanced fire-safe materials and enumerated its goals in a high-level materials research and development plan (Lyon and Eklund, 1993), and also created a preliminary detailed plan for the work (Lyon, 1994). The FAA plans and goals for fire-resistant materials research are summarized in Appendix B. According to the program plan, the objective of the program is to discover the fundamental relationships between the composition and structure of materials and their behavior in fires to enable the design of a totally fire-resistant cabin for future commercial aircraft. Research will be basic in nature and will focus on synthesis, characterization, modeling, and processing of new materials and materials combinations to improve the fire performance, increase the functionality, and reduce the cost of next-generation cabin materials. The FAA Technical Center began acquiring staff and laboratory equipment for this program in 1993. The program is envisioned to be a long-range effort to develop fire-safe materials for use on future commercial aircraft that would represent an "order-of-magnitude" improvement in aircraft cabin fire-worthiness. The program has the following goals: determine the fundamental relationships between the composition and structure of materials and their behavior in fires, use this knowledge to identify and design new materials and material combinations that provide an order-of-magnitude improvement in fire-worthiness, and develop the processing technology to ensure manufacturability and recyclability of advanced fire-safe materials. To provide guidance for this effort, the FAA requested that the National Research Council (NRC), through its National Materials Advisory Board, establish a committee to identify promising fire-resistant1 materials technologies, component design issues, and performance parameters and to recommend research in promising areas. To carry out its charge, the NRC committee held a technical conference at which the participants assessed the state of the an of fire-resistant materials, reviewed ongoing research in improved materials, summarized significant findings, and suggested objectives for the FAA advanced fire-safe materials research program. Included in the published conference proceedings (NRC, 1995) are the conference workshop session summaries upon which the committee built its evaluation to arrive at its final conclusions and recommendations for this report. ACCIDENT STATISTICS In the development of their research initiatives, the FAA based much of its planning on how to counter the kinds of accidents that have occurred in the past. Aircraft accident 1   Fire resistance is defined as the property of a materials or assemblage to withstand fire or give protection from it (ASTM, 1994).

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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft statistics for commercial transport aircraft2 and the of aircraft fires are summarized in this section. The FAA reported that for United States transport airlines, its 1981–1990 database showed there had been 1,153 fatalities, of which 535, or approximately half, had been associated with nonsurvivable accidents, and that the National Transportation Safety Board 1964–1988 database showed that about one-third of the fatalities had been associated with nonsurvivable accidents (FAA, 1991). The FAA data show that about 60 percent of the fatalities in survivable accidents are due to impact trauma (i.e., 30 percent of total fatalities), and the other 40 percent are due to fire (20 percent of total fatalities). This section presents a summary of accident data from 1959 through 1993, using the Boeing database, which is representative of all data (Boeing Commercial Airplane Group, 1994). These data cover Western-manufactured commercial transport aircraft heavier than 60,000 pounds gross weight. Turboprop aircraft are not covered. Aircraft manufactured in the former USSR are not included because that database is incomplete. Military operators of commercial-type aircraft are also not included. As shown in Figure 1-1, the number of commercial aircraft has steadily grown from about 1,000 in 1964 to 11,433 in 1993. The number of departures (flights) has increased from less than 2 million in 1964 to 13.86 million in 1993. Figure 1-2 shows that the number of accidents per million departures decreased rapidly from the introduction of jet aircraft in 1959, and has remained relatively constant for the past two decades at about two accidents per million departures in worldwide scheduled passenger operations. Figure 1-3 shows that the number of fatal accidents per million departures also decreased rapidly after 1959 and has remained relatively constant for the past two decades at about one accident per million departures, with about 500 annual fatalities involving occupants of the aircraft. The number of non-fire-initiated accidents that involve fire is about 0.7 accidents per million departures. The number of fire-initiated accidents is about 0.1 accidents per million departures (Murray, 1995). Table 1-1 shows a synopsis of accidents occurring in passenger and cargo, and test, training, demonstration, and positioning operations since jet aircraft were introduced. From 1959 through 1993, there were 398 fatal accidents with 19,298 fatalities, of which 319 accidents and 18,956 fatalities were in passenger aircraft. In the 10-year period 1984–1993 there were 120 fatal accidents with 5,526 fatalities, of which 96 accidents and 5,397 fatalities were in passenger aircraft. About half of accidents occur during final approach and landing, which is only about 4 percent of the flight time. Figure 1-4 shows the primary causes for accidents that occur on final approach and landing. Figure 1-1 Fatal accident rates and fatalities. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company. 2   This study concerns commercial transport aircraft, that is, certified jet aircraft greater than 60,000 pounds maximum gross weight including those in temporary nonflying status and those in use by nonairline operators, but excluding military (and former Soviet Union) operations (Boeing Commercial Airplane Group, 1994:3).

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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft Figure 1-2 Jet aircraft in service and annual departure. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company. Figure 1-5 shows the classification of accident types involved in airline fatalities. The predominant scenario has been controlled flight into terrain (CFIT), wherein the aircraft crashed into the ground while under control of the flight crew. CFIT accidents have been predominantly nonsurvivable. Figure 1-6 shows the primary factors involved in fatal accidents. The data show that in those fatal accidents for which a primary cause has been identified (about 84 percent), the largest factor is attributed to flight crew (more than 50 percent), followed by airplane factors (less than 10 percent), Figure 1-3 Annual accident rates. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company.

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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft TABLE 1-1 Summary of Fatal Accidents   Number of Fatal Accidents Onboard Fatalities Type of operation 1959–1993 1984–1993 1959–1993 1984–1993 Passenger 319 96 18,956 5,397 All-cargo 44 18 174 76 Test, training, demonstration and positioning 35 6 168 53 Totals 398 120 19,298 5,526   Source: Murray (1995). Reproduced courtesy of The Boeing Company. airport or air traffic control factors (less than 10 percent), and maintenance, weather, and miscellaneous items. STATEMENT OF OBJECTIVES There are two principal objectives of this study: Identify promising materials technologies, design issues (both overall and for individual components), and fire performance parameters (for both full-scale and individual components) that, if properly optimized, would lead to improved fire and smoke resistance of materials and components used in aircraft interiors. Identify those fundamental, long-range research topics that hold the most promise for producing predictive technology, new advanced materials, and the required product development to achieve totally fire-resistant and fire-safe interiors in future aircraft. Aircraft are complex systems composed of many components of different materials. The scope of this study is limited to those materials and parts that compose the aircraft interior and are discussed more fully in Chapter 2. The aircraft interior is considered here to be any parts and materials within the Figure 1-4 Causes of accidents in final approach and landing. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company.

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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft Figure 1-5 Fatalities classified by type of accident. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company. Figure 1-6 Primary causes of fatal accidents. Source: Boeing Commercial Airplane Group (1994). Reproduced courtesy of The Boeing Company.

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Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft structural shell of the aircraft, including cabin furnishings; ceiling, wall, and floor panels; cargo compartment and containers; insulation; wiring; lighting; ducts; windows; and lavatories. Payload items, such as luggage, items, other cargo, newspapers, magazines, the clothing of passengers, and food-related items are important to such fire-related issues as ignitability and generation of smoke and toxic products, but the fire resistance of these items is not considered in this study because they would be very difficult to control. However, the impact of such items as sources of heat in aircraft interiors during crashes should be assessed when evaluating and modeling the fire-resistance qualification and testing conditions. Fire safety systems such as water mist, hoods, vents, and fire suppression systems may affect the criteria used to establish performance goals for the development of fire-resistant materials. These systems, while providing additional benefits in fire safety, were not within the scope of this study. Aircraft interior materials must be lightweight and meet engineering, wear, and cosmetic requirements, in addition to having desirable fire-safety characteristics. In meeting all of these requirements, it is important to recognize that there are not likely to be optimal materials that will, under all possible circumstances, be completely nonflammable and incapable of generating smoke and toxic products. Furthermore, materials processing requirements may limit the application of materials technologies that are otherwise preferred in terms of fire safety. These considerations dictate an approach to the principal study objectives set forth above that begins with defining the most likely fire scenarios to be experienced and how long the aircraft interior must remain safe once a fire occurs. Although there have been some in-flight fires, catastrophic fires are generally post-crash related. In the past, in-flight fires have caused only a very small fraction of fire deaths. For example, according to FAA data, there has been only one in-flight fire death in U.S.-registered commercial transport aircraft (and that death was a suicide). In non-U.S.-registered aircraft, the few catastrophic in-flight fires were initiated in inaccessible areas. The committee considered both in-flight and crash fire categories. However, in-flight fires in accessible areas within the aircraft interior were not considered. These fires have traditionally been extinguished quickly by properly trained flight personnel aided by early detection and warning systems and suitable portable extinguishing equipment. In-flight fires in inaccessible areas are more problematic because of the potentially long periods before passengers can be evacuated and the fire extinguished. Long-term fireworthiness and materials that produce extremely low levels of smoke and toxic products are required for such inaccessible aircraft interior components. In-flight fires in inaccessible areas were therefore one focus of this study. For post-crash fire scenarios, the imperative is to provide passengers who survive the crash sufficient time to leave the aircraft without fatal exposure to heat and smoke and toxic fire products. Smoke and toxic products can result in visual obscuration and partial mental and physical impairment, thus indirectly increasing the required evacuation time. Post-crash fire scenarios are extremely varied; however, the committee defined several general categories for such fires in order to better classify typical fire exposures. Both post-crash and in-flight fire scenarios are described in Chapter 3. Finally, this study emphasizes long-term innovation leading to assessments of the fireworthiness of aircraft interiors 10–20 years hence (see Chapter 4). Thus this report addresses the issue of aircraft interiors more than 10 years in the future, including possible high-speed civil transports and large subsonic transports.