Richard E. Lyon

Strategies for developing fireproof aircraft cabin materials are reviewed in light of environmental legislation that restricts the use of halogens in plastics. The important physical and chemical processes of flaming combustion in terms of their effect on the heat release rate of a burning material are flame inhibition, fuel replacement, heat resistance, and intumescence. These fire resistance mechanisms, acting simultaneously or synergistically, are particularly effective at reducing heat release rate of a new generation of transparent plastics suitable for aircraft cabin interiors.

Stanislav I. Stoliarov and Richard N. Walters

The amount of heat that is required to gasify unit mass of material is one of the key properties that define its ignition resistance and fire response. Knowledge of this property is necessary to assess a material’s fire hazard in a particular fire scenario. Nevertheless, even for the most common polymers, the values of this property are not well established. Here, a methodology is presented for determining the heat of gasification using differential scanning calorimetry and applied to a set of ten common plastics and engineering polymers.

James G. Quintiere, Richard N. Walters, and Sean Crowley

This study investigated the flammability of a carbon-fiber composite material for use in aircraft structures. In particular, it considered a composite material manufactured by Toray Composites (America) to Boeing Material Specification 8-276. The objective was to establish a complete set of properties pertaining to the heating and burning characteristics of these materials in fires. Several apparatuses were used, including the cone calorimeter, microscale combustion calorimeter, thermogravimetric analyzer, differential scanning calorimeter, and a flame spread rig to promote spread with preheating by radiation. An attempt was made to measure the thermal conductivity of the composite over a range of temperatures through its decomposition, but the heat losses from the apparatus likely caused an overestimate in the measurement. Data from standard tests were also reported for the Ohio State University calorimeter and the smoke density chamber.

The material burns in a manner similar to a charring material, in that the carbon fibers comprise most of its mass. The composite burns primarily from the vaporization of its resin. It can ignite with a pilot flame after preheating at a low heat flux. When it burns, the resin vapor is forced out of the fiber pores, and pressure causes the material to swell to over twice its volume. In most all cases studied, the composite maintained its rigidity, but its structural strength was not examined after degradation. The material appears to maintain homogeneity in swelling. The fibers create an insulating, char-like structure that causes a reduction in the internal heating, and consequently, the burning rate drops in time. As the burning rate drops, extinction can naturally occur due to insufficient heating. As is common of charring materials, external heat flux is required to sustain burning and flame spread. It should be noted that the carbon fiber can also oxidize under high-temperature conditions, and this was observed even at low heat fluxes. Furthermore, the properties in this report pertain primarily to the characteristics of the resin material, as the carbon fibers are essentially inert.

The data in this report can be used for modeling and explaining the fire behavior of the composite in fire scenarios associated with aircraft operations.

Timothy R. Marker

Twenty hand-held extinguisher tests were performed in the overhead space in both narrow- and wide-body aircraft. These tests simulated a typical hidden fire in the inaccessible area above the cabin ceiling by using a number of small, controllable candle lanterns. The purpose of the tests was to determine the performance of the Federal Aviation Administration-required, hand-held Halon 1211 extinguishers against a fire in this area when discharging the agent through a ceiling-mounted port. In an effort to maximize agent performance, the port design was modified as these tests progressed. The tests indicated that individual hand-held extinguishers did not predictably extinguish fires in the large-volume cabin overhead area typical of a wide-body aircraft, regardless of the port design. However, the use of ceiling-mounted discharge ports combined with hand-held extinguishers was more promising against fires in the more confined and smaller-volume overhead area typical of a narrow-body aircraft. Additional work would have to be performed to further develop and optimize this concept.

Jill Suo-Anttila, Walt Gill , Anay Luketa-Hanlin, and Carlos Gallegos

A computational model designed to predict smoke and gas transport within aircraft cargo compartments has been validated for potential use in the certification process of cargo compartment fire detection systems. The simulations and experiments compared herein represent a spectrum of scenarios that provide confidence in the models’ ability to predict the transport of smoke and combustion products in a variety of conditions. The main variables that changed between the cases were fire location, compartment size, and ventilation. Validation metrics suitable for fire detection system response were selected and, overall, the model favorably predicted these metrics for the selected cases. The model can now be used with improved confidence to simulate certification scenarios of interest to assist in designing the optimum detection systems for cargo compartments.