Commercial airplane manufacturers have been using composite materials in transport airplane components for decades. But since 2011, new large transport airplane build mostly in composite have started commercial service. This is the case of the Boeing 787, and later the Airbus A350. Some industry observers have raised concerns about the state of the science underpinning the expanded use of composite materials in commercial transport category airplanes and Aviation Authorities’ (FAA and EASA) preparedness for this transition. European and US Aviation Authorities are taking actions to address safety-related concerns linked to the use of composite structure, and the GAO (Government Accountability Office) has issue a report in October 2011 to raise its concerns.
Composite materials in transport airplane components are being used for decades. Prior to the mid-1980s, airplane manufacturers used composite materials in transport category airplanes in secondary structures (e.g., wing edges) and control surfaces. In 1988, Airbus introduced the A320, the first airplane in production with an all-composite tail section and, in 1995, the Boeing Company introduced the Boeing 777, also with a composite tail section.
Composite materials used in commercial airplanes typically are produced by combining layers of carbon or glass fibers with epoxy.
In recent years, manufacturers have expanded the use of composites to the fuselage and wings because these materials are typically lighter and more resistant to corrosion than are the metallic materials that have traditionally been used in airplanes.
The Boeing 787 is the first mostly composite large transport airplane in commercial service. The Boeing 787 is about 50 percent composite by weight (excluding the engines). It will carry 210-290 passengers on routes of 7650 NM to 8500 NM.
It will be followed soon by the Airbus A350, having composite material roughly in the same proportion as its Boeing competitor. The A350 Family provides true long-range capability of flying up to 8500 NM, with seating capacities from 250 to 400-plus passengers.
The responsibility of the safety of an airplane, and subsequently of the safety of composite structure, is shared between three parties:
Some concerns have been raised related to the use of large proportion of composite on an airplane structure. These concerns mainly originated from the state of the science underpinning the expanded use of composite materials in commercial transport category airplanes, and the lack of experience with such design. While the GAO did not make any recommendations, it found four safety-related concerns:
Many efforts are ongoing or planned by the Airworthiness Authorities to help address these areas of safety-related concerns. Efforts to address these concerns include issuing new or modified guidance and policy, conducting research, developing and implementing training and collaborating with industry stakeholders.
However, “It is too early to fully assess the adequacy of [Authorities] and industry efforts to address safety-related concerns and to build sufficient capacity to handle and oversee composite maintenance and repair, given that composite airframe structures in currently in-service airplanes are mostly limited to the secondary structures” says the GAO.
Finally, “Several experts reiterated that while not every risk can be known, the use of composites is not revolutionary; rather, it is a new application of technology that has a history in military and general aviation applications.” says the GAO.
Composite technology is not a revolution in aviation, and it was already used in the past for some aircraft parts. However, since 2011, large commercial plane build mostly in composite have started commercial service, and this creates many safety concerns in the aviation community, mainly because of the lack of experience with such design and the huge differences between the safety-proven metal and the composite.
Also, the adaptation of operational and maintenance procedures to fit with composite particularities may have a negative economic impact.
Commercial aviation has grown in history thanks to successive jumps toward unknown areas. At each jump, many questions and worries arose, we eventually made the necessary progress, suited to the new technology and made it safe. Sadly, many accidents also happened further to these jumps, and this was the price to pay.
Large commercial plane build mostly in composite is another jump, and this is probably the future of aviation as it allows designing lighter, more efficient and greener aircraft. But today, an airplane accident due to the use of composite is not an option, and the public opinion cannot accept to pay such a price anymore.
Written in October 2011