Hidden fire in an aircraft overhead inaccessible-area is hazardous to in-flight safety and could lead to catastrophic disaster. In this case, fire detection at the earliest stage requires an improved understanding of the heat and mass transfer in overhead areas with curved fuselage sections. In this effort, an experimental campaign was conducted at the FAA William J. Hughes Technical Center on different fire scenarios for the Boeing747-SP overhead inaccessible-area to advance knowledge on this phenomenon and provide validation data for the Fire Dynamics Simulator (FDS). Extensive work has been done recently to enable computer simulation of fire on complex geometries within this tool. Therefore, we use the experimental data obtained to perform validation of said capability. Model validation results are defined in terms of thermocouple readings measured and computed with satisfactory overall agreement.
The Fuel Tank Flammability Assessment Method (FTFAM) is a Federal Aviation Administration-developed computer model designed as a comparative analysis tool to determine airplane fuel tank flammability as a requirement of Title 14 Code of Federal Regulations Section 25.981. The model uses Monte Carlo statistical methods to determine the average fuel tank flammability of a fleet of airplanes based upon randomly selecting certain unknown variables over defined distributions for a large number of flights. The FTFAM iterates through each flight, calculating the flammability exposure time of each flight given the data input provided by the user. Calculating this flammability exposure time for a sufficiently large number of flights results in statistically reliable flammability exposure data. These calculations can be performed for fuel tank types utilized in transport airplanes, including body tanks located in the fuselage, wing tanks, and center wing tanks. The program can also be modified by the user to determine fuel tank flammability when a flammability reduction means is employed.
This report serves as a user’s manual for this computer model to assist the user in its operation and to discuss the permissible changes that may be made to this model specific to a particular fleet of aircraft. It is updated through version 11 of the FTFAM. The user should reference Advisory Circular 25.981-2A for additional guidance on when to use this model and for a discussion of interpretation of results.
A physically based microscale combustion parameter for early stage fire growth, called the fire growth capacity (FGC) (J/g-K), is derived from a simple burning model. The FGC combines the ignitability and heat release of the material into a single parameter that can be measured in a microscale combustion calorimeter (MCC) using the standard ASTM D7309 method. The FGC measured at microscale (10^6 kg) in the MCC successfully ranks commercial materials according to their behavior in bench (kg) scale flame (UL 94 V) and fire (14 CFR 25) tests. For this reason, FGC is being evaluated by an aviation industry working group as an alternate means of complying with Federal Aviation Administration fire performance requirements of cabin materials in transport category aircraft when a small component of a certified cabin material must be changed due to cost, availability, performance or environmental concerns. The intent of this report is to validate the proposed methodology and criteria for comparing the components of aircraft cabin materials with respect to flammability. Results for twelve industry case studies were collected and analyzed. In 95% of the cases, the proposed similarity criteria successfully detects a significant change in 14 CFR 25 fire test performance of two materials.