Carbon fibers have been used in thousands of planes in the skies above us, including the one that crashed in Tokyo this week. Is the material safe?
The fuselage of the airliner was involved in a collision on a Tokyo runway it was made of carbon composite fibers, and the incident is renewing concern about the challenges of putting out fires involving the material.
The fire promises to be a critical test of the safety of composite materials compared to traditional aluminum aircraft fuselages.
Investigators appear to immediately focus on the communication between the pilots of the two planes and the air traffic controllers at Haneda Airport.
A transcript released Wednesday indicated that the landing Japan Airlines (JAL) A350 had permission to use the runway, but the Japanese Coast Guard plane did not.
Safety experts praise the airline crew after they all managed to escape the burning plane. Five people on the Coast Guard plane were killed.
Composites have been used for many years inside commercial aircraft, as floorboards and other structures.
Boeing built the first commercial airplane with a fuselage and wings made of carbon fiber-reinforced composite materials, the 787. The plane entered airline service in 2011, and about 1,100 were produced.
Airbus followed in 2018 with the A350 – like the two-year-old plane involved in Tuesday’s collision – and sold about 570 of them.
What material is used?
In airplanes, composite materials contain carbon fiber to give greater strength to plastics and other materials.
According to Boeing, they provide a weight saving of about 20% compared to aluminum – a significant amount, considering the amount of less fuel consumed by a lighter aircraft.
Are there any concerns about using carbon fiber?
The strength of the composites was tested during certification by regulators, including the US Federal Aviation Administration (FAA), and Boeing said it made changes to the 787 as a result, but experts say there are limits to our understanding of material performance.
“There has always been a concern about composites catching fire because the fumes are toxic,” said John Goglia, a former member of the US National Transportation Safety Board (NTSB) who investigates accidents in the United States.
“This threat continues until the plane burns, and even after, because those little fibers could be floating in the smoke.”
Did it make a difference in the Tokyo incident?
As the JAL plane caught fire, filling the cabin with smoke, all 379 passengers and crew managed to escape.
“That fuselage protected them from a really terrible fire — it didn’t burn for any length of time and it didn’t allow everyone to get out,” safety consultant John Cox said. “It’s a positive sign.”
Goglia said there is no real evidence showing whether composite coverings are better or worse than aluminum at resisting fire and heat long enough to give passengers a chance to escape.
Aircraft manufacturers are expected to demonstrate that their planes can be evacuated in 90 seconds with half the exits blocked, even as skeptics question the accuracy of tests conducted by the US government.
On Tuesday evening, video captured a fireball on the JAL plane as it continued down the runway after the crash.
“The flammability issue is something they need to pay attention to, but obviously no one [on the aircraft] burned alive,” said aviation attorney Justin Green.
“It looks like the fuselage and seats [made of fire-retardant material] and everything else protected the flight crew and passengers.”
Is the smoke emitted particularly dangerous?
Passengers on the JAL plane said the cabin filled with thick smoke within minutes.
Videos posted by passengers showed people using handkerchiefs to cover their mouths and ducking as they headed for the exits.
There has long been concern about the toxic smoke released when carbon-reinforced composites burn.
As early as the 1990s, the FAA stated that the main health risks from composites found in plane crashes and fires were sharp splinters from exposed material, fibrous dust, and toxic gases generated by burning resins.
“From initial reports, it appears there was a significant amount of smoke in the cabin, and it’s not yet clear whether some of the smoke was from burning composite materials,” said Todd Curtis, a former Boeing engineer who is now a consultant for safety. .
Curtis said a key follow-up for investigators and regulators will be to monitor whether passengers or firefighters were injured by exposure to toxic smoke from the burning composite.
Such injuries could take a long time to manifest, said Steven Marks, an aviation lawyer. He said passengers involved in accidents are usually in shock and often do not immediately recognize the severity of their injuries.
Was it more difficult to put out the fire?
Another concern, experts said, was the amount of time it took Haneda firefighters to put out the fire and the risk to first responders.
Curtis, the former Boeing engineer, said that in both the Haneda crash and the 2013 fire on an Ethiopian Airlines Boeing 787 parked at London’s Heathrow Airport, “putting out the fire took a lot more effort than with a typical airliner fire.”
The official report said the fire at Heathrow started with crossed wires in the plane’s emergency locator transmitter, but added that “resin in the composite material provided fuel for the fire, allowing a fire to burn slow to settle in the crown of the fuselage”.
Curtis said the accident made him worry about fuselage fires on the ground and in the air in 2013, “and those concerns haven’t gone away.”