The FAA is re-evaluating the flammability testing used to certify Boeing’s 787 Dreamliner after reports that the resins used in the composite materials provided “fuel for the fire” on the parked aircraft at Heathrow back in 2013.
The report conducted by British air accident investigators say the fire, which started on the empty Ethiopian Airlines 787 from a short circuit in a lithium battery powering an emergency beacon, was fed by the resin in the composite materials that forms the aircrafts fuselage.
The trapped battery wires compromised the environmental seal between the battery cover plate and the emergency beacon, providing a path for flames and battery decomposition products to escape from the beacon. The flames directly impinged on the surrounding thermo-acoustic insulation blankets and on the composite aircraft structure in the immediate vicinity of the emergency beacon. This elevated the temperature in the fuselage crown to the point where the resin in the composite material began to decompose, providing further fuel for the fire. As a result, a slow-burning fire became established in the fuselage crown and this fire continued to propagate from the ELT location, even after the energy from the battery thermal event was exhausted.
Speaking anonymously to the Seattle Times an official close to the investigation said;
The standards used in testing didn’t assume there would be insulation to trap the heat and energy and that the accident clearly demonstrates that if an intense fire starts on an airplane, the resin in the composites will burn and create a self-sustaining fire.
Regulators had not anticipated the circumstances of the Heathrow fire when flammability tests were done on the 787 during certification and because of these findings, the FAA is said to be re-evaluating the current flammability and toxicity testing of composite aircraft materials and will research new test methods for future certification. The results have not been published yet.