Patricia Cahill

This document describes the electrical short circuit and current overload tests that were conducted on wires used in commercial transport category aircraft. This testing was conducted to evaluate the fire potential that may result from electrical faults. Results of this testing showed that circuit breakers provide reliable over current protection and that circuit breakers may not protect wire from ticking faults but can protect wire from direct shorts. It also showed that circuit breakers may not safeguard against the ignition of flammable materials by ticking faults. Preliminary testing also indicated that direct short circuits are not likely to start a fire and that direct short circuits do not erode insulation and conductors to the same degree that ticking faults do.

Matthew B. Wolf

A mathematical model was developed that could adequately describe experimentally determined transient changes in metabolic rate (MR.), an9 core and skin temperatures of human beings exposed to water-immersion conditions (0 to 28 DC). The model as the basic 25-node description of Stolwijk and Hardy, as modified to apply to a male with medium fat content. The MR increase induced by shivering was described by 3 components sensitive to 1) time-rate of change of skin temperature, 2) the product of change of skin and head-core temperatures and 3) the product of skin temperature change and the time-rate of change of head-core temperature. The model was also able to closely predict the changes in MR and skin temperatures induced by exposure to cold air. However, the predictions of rectal temperature changes were in the opposite direction to the experimental data for this case. The model was modified to describe the effects of spraying an individual with water on their head, arms and torso to simulate the action of a cabin water spray system (CWSS) activated by a fire in an airplane. The model predicted that an individual, after being sprayed and exiting into a cold and windy environment, would encounter only a minor increase in thermal stress, compared to the dry state. We conclude that mathematical simulation is an effective method of predicting thermal behavior of humans under a variety of cold conditions.

A.M. Cobbett

Evidence from aircraft accidents indicates that cabin crew can have a positive impact on passengers’ ability to effectively evacuate an aircraft. A program of 24 competitive evacuations were performed in an attempt to determine the effect of cabin crew behavior upon rate of egress from a stationary aircraft simulator. Three cabin crew behaviors were assessed, two assertive cabin crew, two non-assertive cabin crew and no cabin crew. The evacuations were conducted on board a Boeing 737 cabin simulator.

A totals of 651 volunteers (64.4% male) with a mean age of thirty years participated. All volunteers received a f10 attendance payment. The first 75% off the aircraft received a f5 bonus payment in an attempt to simulate a rush for the exits and to motivate participants to try to egress as quick as possible.

Cabin crew behavior was found to have a significant effect upon passenger’s evacuation times. Two Assertive cabin crew produced the fastest mean evacuation times. The results indicated that assertive cabin behavior is of most importance in the initial stages of an evacuation as it sets the speed for the later stages. When passengers received no help from cabin members their evacuation times were significantly slower than those passengers who had received help from assertive and non-assertive cabin crew.

Passengers evacuated faster when two doors rather than a single exit were available however in the latter stages of the emergency evacuations individuals’ egress time was no longer affected by the number of exits available. At this stage fewer blockages and queues at exits occurred subsequently the number of exits available had no effect on passengers’ evacuation times. There was however, no significant difference between the two types of exits utilized in this study.

The number of bonuses a passenger received was found to be significantly affected by gender and age, males received more bonuses as did younger passengers. Passenger’s questionnaire responses also indicated that they perceived assertive cabin crew members to have greatly aided their escape.

J. Michael Barrientos

On April 6, 1993, China Airline’s MD-11 Flight 583 underwent severe turbulence caused by the inadvertent deployment of the wing leading edge slats. The aircraft experienced three violent pitch oscillations and a loss of altitude of about 5000 feet which significantly damaged the interior of the cabin. Upon examination of the passenger seats in the cabin interior, excessive wear was noticed with the fire-blocking layer (FBL) material which encapsulates the foam cushions that protect them in the even of a fire. Concerns arose with this FBL material manufactured by Testori of Italy, as well as other FBL material in service, with regard to their effectiveness in protecting the foam cushions from fire. Samples of this type of material underwent several flammability tests at the FAA Technical Center International Airport, NJ, and chemical analysis and microscopic examination at Du Pont Fibers Laboratory in Wilmington, Delaware.

Robert A. Filipczak

Halon 1301, Halon 1211, and eleven alternative fire-fighting agents were compared for extinguishment effectiveness and thermal decomposition product generation, using a laboratory-scale test apparatus having methane as the fuel. Chemical analysis was conducted using a magnetic sector mass spectrometer with simultaneous measurement of oxygen consumption and carbon dioxide, water and acid gas production. Chemical mechanisms are advanced to explain how halongenated hydrocarbons extinguish fires. The major conclusion was that the alternative agents were not as effective at fighting fires as Halons and those greater amounts of acid gases were produced during extinguishment. Hydrogen fluoride was found to be the predominant thermal decomposition product for all agents.