Ray Cherry and Kevin Warren

The objective of this analysis was to assess the potential benefits, in terms of reduction of fatalities and injuries, resulting from improvements in fuselage burnthrough resistance to ground pool fires. The process employed for assessing benefit is considered to give reasonably accurate and consistent results within the limitations imposed by the available data. The methodology gives a reasonable assessment of the tolerance on the predicted levels.

Fire hardening of fuselages will provide benefits in terms of enhanced occupant survival and may be found to be cost beneficial if low-cost solutions can be found. The maximum number of lives saved per year in worldwide transport aircraft accidents, over the period covered by the data, was assessed to be 12.5 for the aircraft in its actual configuration and 10.5 for the aircraft configured to later airworthiness requirements.

Steven M. Summer

This report discusses experiments performed within a simulated fuel tank approximately 1/20 the size of a typical B-747 center wing fuel tank (CWT). The vapors generated within the ullage of this tank were analyzed under different mass loadings in an effort to determine the effects of the mass loading and fuel distribution. It was determined from these tests that in order to have a substantial effect on the flammability of the vapor within the CWT, the mass loading would have to be somewhere between 0.08 and 0.15 kg/m3. A substantial effect was defined as a minimum 20% decrease in the maximum hydrocarbon count when compared to the average of all tests conducted with larger mass loadings. In addition, it was found that while the distribution of the fuel has no effect on the peak flammability (vapor composition) that is reached, it does have a significant effect on how long it takes to reach the final state. The less dispersed the liquid fuel is, the longer it will take the vapor to reach its maximum flammability point.

Douglas A. Ingerson

The primary fire suppressant used in commercial aircraft engine nacelles and auxiliary power units is Halon 1301. The period of fire suppression system development and its certification testing may be an arduous task requiring the discharge of substantial quantities of fire suppressant. Additionally, to demonstrate compliance with federal regulations, engine nacelle fire suppression systems are discharged in flight or at varying conditions simulating flight. These tests are recorded and evaluated with specialized gas analysis equipment. Currently, the certification process requires releasing Halon 1301 to accomplish such approvals.

Based on the Montreal Protocol and its amendments, the halon family of fire suppressants has been eliminated from production. This action is in response to the destructive capacity of halon with respect to the ozone layer within the atmosphere. This technical note describes a procedure for utilizing an ozone-friendly simulant during fire suppression system development and certification testing. It demonstrates a realistic potential to eliminate the release of Halon 1301 for purposes other than actual fire suppression. This step is perceived as an interim process to assist with the reduction of Halon 1301 release during the transition to chemicals which meet the intent of the Montreal Protocol.

Richard E. Lyon

The thermal and chemical processes which occur in the solid state during flaming combustion are examined. A phenomenological model of fuel generation provides the relationships between macroscopic flammability parameters and polymer chemical structure and shows how the coupling of thermal diffusion and chemical kinetics occurs naturally in the pyrolysis zone. Fire behavior and flammability of solid polymers are predicted using the ignition temperature, heat of combustion, heat of gasification, and char yield calculated from the chemical structure; and the results are compared to experimental values. The objective of this work is to develop a consistent, solid-state physical chemistry of flaming combustion which bridges the gap between fire and material sciences to help guide the discovery of new, more fire-resistant polymers

Thomas Cleary and William Grosshandler

As part of the National Aeronautics and Space Administration (NASA) initiated program on global civil avaition, NIST is assting the Federal Aviation Administration in its research to improve fire detection in aircraft cargo compartments.