David Blake

This technical note documents the results of a project to evaluate the ability of flight attendants to extinguish cargo fires in small Class B cargo compartments. Thirteen fire tests were conducted in a modified Shorts 330 airplane in which flight attendants attempted to extinguish cargo fires. Some of the selected test variables included the cargo compartment size, the width of the access door, the size and type of fire extinguishers available, the presence and absence of an unobstructed center aisle in the cargo compartment, the type of Protective Breathing Equipment (PBE), and the delay between the smoke detector alarm and the start of the firefighting efforts. The results of the testing indicated that in most cases the flight attendants were unable to successfully extinguish these fires. 17.

Timothy R. Marker

This report summarizes the research and full-scale tests undertaken by the Federal Aviation Administration (FAA) to evaluate the fuselage burnthrough resistance of transport category aircraft that are exposed to large postcrash fuel fires. Twenty-eight full-scale tests were conducted in a reusable fuselage test rig to determine the effectiveness of thermal-acoustical insulation improvements in preventing or delaying fuselage burnthrough. The testing showed that the method of attaching the insulation to the fuselage structure had a critical effect on the effectiveness of the insulation material. In addition, the composition of the insulation bagging material, normally a thermoplastic film, was also shown to be an important factor. A number of fiberglass insulation modifications and new insulation materials were shown to be effective in varying degrees. For example, a heattreated, oxidized polyacrylonitrile fiber (OPF) encased in a polyimide bagging material prevented burnthrough for over 8 minutes. When contrasted with current insulation materials, which were shown to fail in as little as 2 minutes, effective fire barriers such as the OPF insulation offer the potential of saving lives during a postcrash fire accident in which the fuselage remains intact.

Sanjeev Gandhi, Richard E. Lyon

Concerns about the potential health hazards of burning fiber-reinforced polymer composites in aircraft fires parallel the rising usage of these materials for commercial aircraft primary and secondary structures. An overview of the nature and the potential hazards associated with airborne carbon fibers released during flaming combustion of aircraft composites is presented. The current data derived from animal studies are insufficient to determine the acute toxicity of carbon fibers from burning composites. Further work is needed to examine the adverse health effects of volatile organic chemicals and to assess if any synergistic interactions exist with the fibers.

Richard E. Lyon, Stacey M. Hackett, Richard Walters

The heats of combustion for 47 commercial and developmental polymers of known chemical structure were determined using an oxygen bomb calorimeter according to standard methods. The experimental results were compared to thermochemical claculations of the gross heat of combustion from (1) oxygen combustion and (2) group additivity of the heats of formation of products and reactants. The polymers examined were thermally stable, char-forming thermoplastics and thermoset resins containing a significant degree of aromaticity and heteroatoms including nitrogen, sulfur, phosphorus, silicon and oxygen in linear and heterocyclic structures. The gross heats of combustion calculated from polymer enthalpies of formation and oxygen comsumption thermochemistry were within 4 and 5 percent respectively, of the experimental values from oxygen bomb calorimetry. The heat released by combustion per gram of diatomic oxygen comsumed in the persent study was E+13.08+ 0.87 kJ/g-O2 for polymers which combusted completely (n+46). The value is indistinguishable from the universal E+13.1 kJ/gO2 used in oxygen comsumption calorimetry.

Richard K. Jeck

About 7600 nautical miles (nm) (14,000 km) of select ice particle measurements over the United States have been compiled into a single, computerized database for use in characterizing ice crystal and snowflake (generally termed ice particle) size distributions and mass concentrations at flight altitudes. Data are from 50 research flights by six agencies in eight flight research projects using Particle Measuring Systems' one-dimensional (I-D) and two-dimensional (2-D) particle sizing probes. Primary recorded variables are average particle size distributions in the range 0.1 to 10 mm from each of 1625 micro physically uniform cloud intervals or other convenient distances in wintertime clouds, snowstorms, cirrus, and other' high-altitude clouds. The findings are that, generally, the largest particles and the greatest concentrations of total ice particle mass (TIPM) are confined to altitudes below 20,000 ft (6 km). There, particles of 10 mm in maximum dimension and TIPM's up to about 3 glm3 may be found. Above 20,000 ft, particles are smaller than 2 mm and TIPM's are less than 0.2 glm3 in the cirrus 'and the upper reaches, of deep winter storm clouds that are found at these levels. Exceptions are thunderstorm anvil clouds where 10 mm particles and TIPM's of at least 1 glm3 can be found up to at least 30,000 ft (9 km). Anvil clouds and stratiform clouds associated with warm season mesoscale convective systems have provided some of the largest TIPM's, the greatest particle concentrations, and the largest particle sizes at high and mid altitudes, respectively. In contrast to super cooled cloud droplets where the largest liquid water (mass) concentrations are confined to short distances of3 nm or less in convective clouds, the largest average TIPM's in glaciated clouds have been found in layer clouds over distances up to 30 nm. Based on these analyses, a summary table of ice/snow cloud characteristics is proposed for use as engineering specifications for aviation purposes.