Louise C. Speitel and Richard E. Lyon

A kinetic scheme was used to model the human blood concentration history of halocarbon extinguishing agents as a function of agent discharge amount, compartment size, ventilation rate, cabin pressure, and altitude of aircraft. This methodology recommends discharge limits of halon replacement extinguishing agents that produce maximum blood concentrations safely below the adverse effect level. This report provides the technical basis for an update of guidance on the use of hand-held fire extinguishers on aircraft contained in Federal Aviation Administration Advisory Circular 20-42C. Safe-use limits are established for halon replacement extinguishing agents by using an instantaneous blood concentration of halocarbon as a criterion for adverse effect instead of a critical dose (concentration-time product).

Stanislav I. Stoliarov, Sean Crowley, and Richard E. Lyon

This study provides a thorough examination of whether a numerical pyrolysis model, which describes transient energy transport and chemical reactions taking place in a one-dimensional object, can be used as a practical tool for prediction and/or extrapolation of the results of fire calorimetry tests. The focus is on noncharring polymers, in particular—poly(methylmethacrylate), high-impact polystyrene, and high-density polyethylene. First, relevant properties of these materials were measured and/or obtained from the literature. Subsequently, the values of these properties were used to simulate gasification and cone calorimetry experiments, which were performed under a broad range of conditions. A comparison with the experimental results indicates that the model gives reasonably good predictions of the mass loss and heat release histories. It also predicts the evolution of temperature inside the material samples.

R.G.W. Cherry & Associates Limited

This report describes the methodology and results of a study undertaken for the Federal Aviation Administration into the characteristics of Fuselage Breaks and their effects on occupant survival in ground pool fire Accidents. For those accidents where the fuselage remains largely intact, a determination has been made of the nature of any Fuselage Ruptures resulting from the accident sequence. An assessment has also been made as to whether the probability of occurrence of ground pool fires is different for Aircraft with Wing Mounted Engines than for Aircraft without Wing Mounted Engines. The Cabin Safety Research Technical Group Aircraft Accident Database was used to select Survivable Accidents that occurred during the period 1967 to 2000, to Passenger carrying western world turbojet aircraft. Where appropriate to the study these accidents were analyzed in depth using Accident Reports and other data published by National Airworthiness and Investigating Authorities.

The results of the study suggest that further data would be needed to determine any significant difference that might exist between the probabilities of occurrence of a ground pool fire accident for Aircraft with Wing Mounted Engines and for Aircraft without Wing Mounted Engines. All that can be determined, within the constraints of the size of the existing data set, is that any difference that might exist is unlikely to be large. Whilst it is likely that the majority of ground pool fire accidents in which the aircraft remains largely intact sustain Fuselage Ruptures, there are insufficient data available to establish the size of any such ruptures.

For the Fuselage Break accidents studied the majority involved at least two breaks. Whilst the number of Fuselage Breaks does not appear to be influenced by the intensity of the impact the probability of a Fuselage Break tends to increase as the impact becomes more severe. Although no firm conclusions can be made, it is considered likely that approximately half of the Fuselage Breaks occur at a point of structural discontinuity. The occurrence of a Fuselage Break in ground pool fire accidents seems to result in a more severe fire threat to the occupants. However, it is evident that for the majority of ground pool fire accidents studied, involving a Fuselage Break, the occupants used the breaks as an escape route. In order to ascertain the net effects of Fuselage Breaks on occupant survival a Monte Carlo simulation model was developed. The primary value of the model was an assessment of the effects on occupant survival of changes in the probability of occurrence of Fuselage Breaks. Based on the results derived from the model it is considered that Fuselage Breaks have a net adverse effect on occupant survival. The change in the number of Fatal Injuries, F, with changes in the probability of a Fuselage Break ΔB for an aircraft with N occupants may be reasonably well represented by the following equation:

R.G.W. Cherry & Associates Limited

As part of a project commissioned by the Federal Aviation Administration data have been gathered on the relative proportion of accidents that involve Ground Pool Fires and statistical data on the following:

• Time to initiate an evacuation
• Time to complete an evacuation
• Time to arrival of fire-fighters
• Time for fire-fighters to establish control in a Ground Pool Fire accident

The data was extracted from accident reports and other information published by Investigating and Airworthiness Authorities using the Cabin Safety Research Technical Group Aircraft Accident Database as the search facility.

Robert I. Ochs

A new and improved burner was developed to test the fire penetration resistance of thermal acoustic insulation in accordance with Title 14 Code of Federal Regulations (CFR) Part 25.856 (b). This next-generation (NexGen) burner was developed mainly to provide industry with an alternative to the currently accepted burner apparatus manufactured by Park Electric Motors of Atlantic City, NJ. Title 14 CFR 25.856 was written based on the use of the Park DPL 3400 burner; however, the company stopped production of this apparatus shortly after the new test method became final in 2003. The NexGen burner can be considered a direct replacement to the Park-manufactured burner, with several key improvements.

The NexGen burner is based on the same operating principle as the Park DPL 3400, using the same, or very similar, internal components to avoid drastically changing the overall character of the flame. The main difference is the elimination of the electric motor, which provided power to the fuel pump and blower fan in the Park-manufactured burner. In the NexGen burner, these functions have been replaced with regulated and conditioned compressed air and a pressurized fuel delivery system. Compressed air, when metered with a sonic orifice and conditioned to remove heat and moisture, proves to be more consistent over extended periods of time than to using a shaft-driven blower and laboratory air for the burner, thus increasing the repeatability of the NexGen burner. NexGen fuel delivery is provided by applying a head pressure of nitrogen gas on liquid fuel contained in a pressure vessel. This new method eliminates any fluctuations that were previously experienced with the electric motor and shaft-driven fuel pump typical of the Park-manufactured burner.

The exit air velocity and the fuel flow rate of the NexGen burner were matched to that of the Park DPL 3400 burner specifications to produce a flame of similar temperature and heat flux. Initial comparison tests indicated that the NexGen burner provides burnthrough results similar to that of the Park burner when comparing identical materials. Multiple NexGen burners were produced, and all were proven to provide the same results. NexGen burners were shipped to participating laboratories, tested with identical materials, and proven to be reproducible at different locations. This work has shown that an equivalent burner can be fabricated from readily available materials and can be used to test materials according 14 CFR 25.856 (b).