Emma Kelly / Perth
Australia’s RMIT University has completed what is believed to be the first detailed analysis of the fire performance of polymer composite materials used in modern aircraft cabins and structures.
The Australian Transport Safety Bureau-funded programme assesses the fire hazard of current and next-generation polymer composites, ranking them on eight fire properties – time-to-ignition, limiting oxygen index, peak and average heat release rates, total heat release, flame spread rate, smoke and combustion gases.
Glassfibre/phenolic, the composite most often used in aircraft cabins, has “excellent fire reaction performance”, with few next-generation composites displaying superior properties, according to the study. The most-used structural composite, carbonfibre/epoxy, has poor fire resistance and can pose a serious fire hazard, says the report.
Although between 1987 and 1996 only six out of 180 fatal passenger aircraft accidents (3.5%) were caused by fire, it accounts for a greater share of fatalities. From 1992-2001 fire was the fourth highest cause of deaths, at 4.9%, according to the study.
In terms of time-to-ignition, phenolic performs well, with the eighth (out of 26) longest ignition time. But many structural composites possess better resistance to ignition than carbonfibre/epoxy (ranked 15th out of 19). Geopolymer and phthalonitrile, both being evaluated by the US Federal Aviation Administration, have excellent ignition resistance, says the report.
Phenolic also performs well in limiting oxygen index, requiring the second highest concentration of oxygen to support combustion, while several high-temperature thermoplastic and thermoset polymer composites perform better than carbonfibre/epoxy. But the report points out the best performing composites are expensive, with little chance of being used.
Glassfibre/phenolic has the fifth lowest peak heat release rate, and seventh lowest average rate, but carbonfibre/epoxy composite is near the foot of the table with one of the highest. Phenolic has the best performance in total heat release.
Carbonfibre is one of the worst materials for producing smoke and also produces relatively high levels of carbon monoxide and carbon dioxide, the report says.
Source: Flight International
