On January 2, 2024, an Airbus A350 aircraft of Japan Airlines collided with a plane of the Japan Coast Guard and caught fire immediately after landing at Haneda Airport. The A350 that burned down in this accident used carbon fiber composite materials with lower heat resistance than metals. Therefore, this accident also became the first opportunity in the world to test the safety of the new generation of passenger planes using carbon fiber reinforced composite materials in the event of a major fire.
Japan Airlines Flight 516, an Airbus A350, extensively utilized carbon fiber composite materials in its fuselage and wings, and the recent collision and fire incident may bring this material into the spotlight. Videos of the accident show the Japan Airlines aircraft moving along the runway and coming to a stop, only to be engulfed by flames. Notably, despite the fire, all 379 passengers on board the Japan Airlines aircraft safely evacuated. However, of the six people on the smaller Japan Coast Guard aircraft, five perished.
The photos from the accident scene show that the body of the A350 has been burned to ashes.Although the Japan Transportation Safety Board and the Metropolitan Police Department are investigating the cause of the accident, the aviation industry is eager to confirm the durability of carbon fiber reinforced composite materials.
Anthony Brickhouse, an aviation safety expert at Embry-Riddle Aeronautical University, said that this accident is the first case study of a large-scale use of carbon fiber reinforced composite material in passenger aircraft, not only in terms of fire safety but also in terms of survivability in a crash.
Airbus has stated that the body of the A350 uses carbon fiber composite materials, titanium alloys, and aluminum alloys to improve corrosion resistance, ease of maintenance, and to create a lightweight, cost-effective aircraft.The company also pointed out that carbon fiber skin is less likely to burn than metal skin. Therefore, in this accident, this material has attracted the attention of experts.
In the early 2000s, when Boeing in the United States and Airbus in Europe invested in the 787 Dreamliner and A350 respectively, people had high hopes for these airplanes made of lightweight and high-strength carbon fiber reinforced composite materials. They hoped to significantly reduce fuel consumption and lessen the burden of body aging, maintenance, and inspection.
Not long after entering service, the Boeing Dreamliner was grounded due to fires caused by battery failures and temporarily ceased flying in early 2013; in July 2013, an Ethiopian Airlines plane had to undergo repairs due to a fire caused by a short circuit in the life radio. However, these fires did not completely destroy the aircraft's exterior shell.
The overall structure of the Airbus A350 includes 53% carbon fiber reinforced composite materials, including the fuselage, tail, and most of the main wings. Several experts have stated that all passengers and crew members could eject safely while the aircraft structure remained intact, which has restored confidence in carbon fiber composite materials. This material has been certified under special conditions.
However, some experts have pointed out that, as it stands, it is still unclear how the A350's fuselage skin managed to withstand the fire for a certain period of time, or what technical lessons can be learned. It is premature to draw comprehensive conclusions.
Mr. Brikhouse compared this incident to the 2013 July accident involving an Asiana Airlines Boeing 777 that failed to land and caught fire, resulting in the death of three passengers. He believes that this will provide useful information for understanding the differences in the combustion processes of carbon fiber reinforced composite materials and aluminum materials.
Biyon Ferm from the aviation industry information company Leam News and Analis stated that, compared to aluminum aircraft, carbon fiber reinforced composite material aircraft have several advantages. For instance, aluminum melts at around 600 degrees Celsius and conducts heat, but carbon fiber can withstand approximately six times the high temperature, continuing to smolder without melting or emitting flames.
In a firefighter guide published in 2019, Airbus demonstrated that the A350 has "an equivalent level of safety" compared to traditional aluminum fuselages, and various tests indicated that it "enhances resistance to fire penetration." However, Airbus also warned that even if the surface of the carbon fiber reinforced composite material remains, prolonged exposure to high temperatures could lead to the aircraft losing structural integrity.
According to Airbus, previous tests have shown that the fire resistance of carbon fiber reinforced composite materials is the same as that of aluminum. The spokesperson added that the airline had conducted a full evacuation test on the A350-1000 in the presence of authorities as early as 2018.
An executive from a German fire safety company stated that many factors can affect the flammability of composite materials, including their structure, textile materials, and the layers of flame retardants used. The executive said, "One thing we are certain of is that even aluminum cannot withstand the high temperatures produced by the combustion of kerosene."
According to TBS, citing fire authorities, it took them over six hours to finally extinguish the fire on the A350 after it continued to burn. Some experts have questioned and suggested an investigation into why the Haneda Airport fire department took so long to put out the blaze.