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.

Advisory Rulemaking Committee - Task Group 4

This report is the findings of the Fuel Tank Foam and Expanded Metal Products Task Group, which was formed as a portion of the Fuel Tank Harmonization Working Group activity established in January 1998. The FAA initiated this activity by the issuance of a Harmonization Terms of Reference entitled "prevention of Fuel Tank Explosions" on 16 December 1997. The Working Group's stated task was to study means to eliminate or reduce fuel tank flammability and to propose regulatory changes to the FAA Aircraft Rulemaking Advisory Committee.

David Blake, Timothy Marker, Richard Hill , John Reinhardt, Constantine Sarkos

This report describes recent research by the Federal Aviation Administration (FAA) related to cargo compartment fire protection in large transport aircraft. A gaseous hydrofluorocarbon, HFC-125, was compared to Halon 1301 in terms of fire suppression effectiveness and agent decomposition levels in the cargo compartment and passenger cabin during full-scale tests involving a bulk-loaded cargo fire. Also, a zoned water mist system was designed and evaluated against a bulk-loaded cargo fire. An exploding aerosol can simulator is being developed to provide a repeatable fire threat for evaluation of new halon replacement agents. The potential severity of an exploding aerosol can inside a cargo compartment and the effectiveness of Halon 1301 inerting was demonstrated. Tests were also conducted to determine the effectiveness of Halon 1301 against a cargo fire involving oxygen canisters. Finally, HFC-125 was evaluated for use as a simulant for Halon 1301 during cargo compartment approval testing to demonstrate compliance with applicable FAA regulations.