The FAA microscale combustion calorimeter (MCC) operates by burning the evolved gases from a thermally degrading sample and measuring the oxygen consumption to calculate a heat release rate. Recent method developments using hyphenated MCC techniques enables measurements of the effect of vitiation on toxic combustion gas yields. Stoichiometric fuel to oxygen ratio tests were performed where a constant fuel to oxygen ratio relative to the stoichiometric ratio, Φ, in the combustor is controlled throughout the sample decomposition. When Φ < 1, combustion is fuel lean (over ventilated). When Φ > 1, combustion is fuel rich (vitiated).

The MCC was coupled with an infrared spectrometer (MCC-IR) and a multigas analyzer (MCC-Testo), which were used to monitor gases and evaluate combustion toxicity at different Φ and combustion temperature set points. These hyphenated techniques demonstrate a unique capability to elucidate the effect of constant fuel to oxygen ratios on combustion product yields. Measurements made at different Φ’s will help to better understand the flame chemistry and the mix of complete/incomplete combustion products for various aircraft materials throughout the different stages of a full-scale fire. Combustion equivalence ratios of 0.5, 1.0 and 1.5 were evaluated in this study. A set of hydrocarbon materials with elemental compositions, including C, H, N, O, and S, were examined to provide a spectrum of gaseous combustion products where a small set of potential toxic combustion products could be evaluated. Yields of the gaseous decomposition/combustion products were compared as a function of equivalence ratio for the set of materials. Trends in combustion products produced at different oxygen ratios correlate with large-scale fire test data from the literature and showed an increase in toxic product yields with increasing Φ.

This study introduces a novel approach to enhance fire protection in aircraft cargo compartments, motivated by the urgency to address catastrophic in-flight fires recorded between 2006 and 2011. The method uses ultra-high frequency (UHF) radio frequency identification (RFID) temperature sensing tags and advanced algorithmic analysis to enhance fire detection capabilities within unit load devices (ULDs). This approach significantly reduces detection times while minimizing false alarms.

The first objective was to create an economical, battery-free fire detection system with UHF RFID temperature sensing tags installed within ULDs. This positions the temperature sensing tags closer to potential fire sources than traditional cargo compartment ceiling-mounted smoke detectors. Wireless temperature sensing tags allow the ULDs to move in and out of aircraft. Passive sensors address the challenges of batterypowered systems, such as battery changes and thermal runaway risks.

The second objective sought to enhance the RFID-based system with near real-time temperature monitoring capabilities within ULDs. The system provides accurate temperature trend analysis by incorporating a moving average convergence divergence (MACD) algorithm adapted from financial markets. This significant advancement improves fire detection times and supports communication of conditions within ULDs to flight crews, enabling quicker response actions.

The number of thermal runaway incidents from portable electronic devices (PEDs) in the aircraft cabin is growing at a notable rate. Recent data indicates that lithium battery incidents occur on average more than once per week on passenger aircraft. In response to this problem, many airlines have adopted the use of fire containment products as a means to mitigate the spread of fire and toxic fumes. An evaluation was conducted by the FAA to assess the effectiveness of commercially available fire containment products and assess their capability to mitigate the release of smoke, flames and shrapnel produced from a PED fire.

Fire containment products were procured from five different manufacturers and tested with three different fire loads, a tablet containing a 30 Watt-hour (Wh) battery, a 96 Wh power bank and a 154 Wh video camera battery. Products were only evaluated according to the maximum capacity that the product was advertised to withstand.

Key findings from this study include:

• The performance of fire containment products varied amongst the different products. Multiple products struggled to contain the hazards of PED fires near the maximum allowable energy limits permitted on aircraft (100 Wh and 160 Wh).
• Product performance varied based on the PEDs interior cell configuration and the rate at which cells experienced thermal runaway. Short periods between thermal runaway events can produce significant gas buildup, which some products are unable to vent quickly enough. This can create pressure spikes and mechanical failures (rips/tears) in the product.
• The suppression equipment included with some of the containment products was found capable of knocking down flames but unable to prevent heat propagation to adjacent cells.

Testing suggests that some containment products cannot currently meet the airlines’ present expectations for product performance. Further testing on the use of fire containment products may be needed to ensure the safety of aircraft occupants.