Aviation Safety: Status of FAA's Actions to Oversee the Safety of Composite Airplanes
Published: 2011-09-21T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Composite materials, made by combining materials such as carbon fibers with epoxy, have been used in airplane components for decades. Although composites are lighter and stronger than most metals, their increasing use in commercial airplane structures such as the fuselage and wings has raised safety concerns. Boeing's 787 is the first mostly composite large commercial transport airplane to undergo the certification process. The Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) certify new airplane designs and evaluate the airworthiness of novel features--like composite structures--against existing safety standards, which are often based on the performance of metallic airplanes. In August 2011, FAA and EASA certified the 787, which is expected to enter commercial service in the fall of 2011. GAO was asked to review FAA's and EASA's certification processes and FAA's oversight of the composite airplanes once they enter service. GAO examined how FAA and EASA assessed the use of composite materials in the Boeing 787 fuselage and wings, and the extent to which FAA has addressed safety-related concerns associated with the repair and maintenance of composite airplanes. GAO reviewed certification documentation, conducted a literature search, discussed repair and maintenance issues with experts, and interviewed FAA and EASA officials and Boeing representatives. GAO is not making recommendations in this report. FAA, EASA, Boeing, and others provided technical comments, which
section_title: What GAO Found
paragraphs: GAO found that FAA followed its certification process in assessing the Boeing 787 airplane's composite fuselage and wings against applicable FAA airworthiness standards. FAA applied five special conditions when it found that its airworthiness standards were not adequate to ensure that the composite structures would comply with existing safety levels. These special conditions require Boeing to take additional steps to demonstrate the 787's structures meet current performance standards. FAA also granted Boeing an equivalent level of safety finding when the manufacturer determined it could meet the standard but prove it differently from the method specified in that standard. On the basis of a review of FAA's special condition requirements, Boeing submissions, and discussions with FAA and Boeing officials, GAO found that FAA followed its process by documenting the technical issues related to the design of the composite fuselage and wings, determining the special conditions and equivalent level of safety finding, obtaining public comments on draft special conditions, and monitoring Boeing's compliance with those conditions. EASA also assessed the use of composite materials in the Boeing 787 and relied on FAA to oversee Boeing's compliance in some cases. EASA's process for determining whether its existing airworthiness standards were adequate to ensure the 787's composite fuselage and wings met current levels of safety was similar to FAA's special conditions process and resulted in some additional review items, partly because of differences in their respective standards. On the basis of expert interviews and a review of literature, GAO identified four key safety-related concerns with the repair and maintenance of composites in commercial airplanes--(1) limited information on the behavior of airplane composite structures, (2) technical issues related to the unique properties of composite materials, (3) standardization of repair materials and techniques, and (4) training and awareness. None of the experts believed these concerns posed extraordinary safety risks or were insurmountable. FAA is taking action to help address these concerns identified by GAO related to the repair and maintenance of composite airplane structures. However, until these composite airplanes enter service, it is unclear if these actions will be sufficient.

section_title: Letter
paragraphs: Commercial airplane manufacturers have been using composite materials  in transport airplane components for decades. Composite materials used  in commercial airplanes typically are produced by combining layers of  carbon or glass fibers with epoxy. Since the 1980s, manufacturers have  used composite materials for some airframe structures, such as the tail  section. 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. For example, the Boeing  Company is introducing the 787-8 Dreamliner (787) airplane, which uses  composite materials for the fuselage and wings and is about 50 percent  composite materials by weight, excluding the engines, and Airbus S.A.S. is  designing the A350, an airplane also made primarily of composites.  Regulatory agencies such as the Federal Aviation Administration (FAA) in  the United States and the European Aviation Safety Agency (EASA) in the  European Union are responsible for certifying the design and airworthiness  of new airplanes in their respective jurisdictions. In August 2011, FAA and  EASA certified the design and production of the Boeing 787. Airplanes  such as the 787 and A350 represent a new development for FAA and  EASA, in part because the safety standards used for certification of  airplanes as airworthy were promulgated based on the service experience  of and research on traditional metallic airplanes, which have a much longer  record of service than do composite airplanes.
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 FAA’s preparedness for this  transition. They point to a 3-year delay in the Boeing 787 schedule as an  indication that the industry has not yet reached a level of competency in  the use of composites. Boeing attributes the delays to its development  process and production challenges. FAA has emphasized that its role is  to ensure that new airplanes meet the current level of safety and  performance, regardless of the materials from which they are made. FAA  officials note that the agency’s airplane certification process includes  processes to assess unique airplane design features, which may require  the manufacturer to take additional steps to ensure that current levels of  safety are met.
You asked us to examine FAA’s and EASA’s processes for certifying the  design of U.S.-manufactured new commercial airplanes using composite  materials in airframe structures and FAA’s process for overseeing the  safety of composite airplanes once they are in service. To do so, we  addressed (1) how FAA assessed the use of composite materials in the  Boeing 787 fuselage and wings, (2) how EASA assessed the use of  composite materials in the Boeing 787 fuselage and wings, and (3) the  extent to which FAA’s actions address experts’ safety-related concerns  associated with the repair and maintenance of composite airplanes. We  focused our review on the Boeing 787 because it is the first mostly  composite large transport category airplane for commercial use to go  through the certification process and questions by former Boeing  employees and others have been raised about the safety of its composite  structures.
To fulfill the first two objectives, we reviewed FAA and EASA regulations,  policies, and processes for certifying new airplanes. Specifically, we  focused on the special conditions these agencies applied to the design of  the 787 composite airplane’s wings and fuselage. Many of the outside  concerns raised about the design of the 787 were related to Boeing’s use  of composite materials. We compared FAA’s established process for  identifying technical issues and developing special conditions with the  process used to develop selected special conditions in the certification of  the 787, as well as the process EASA followed in a similar certification  review. We reviewed documents related to the special conditions that  were prepared by FAA, EASA, and Boeing. To address the third  objective, about safety concerns in the repair and maintenance of  composite airplanes, we conducted a literature search and reviewed 39  journal articles and technical papers related to the repair and  maintenance of composite airplanes. These articles and papers were  drawn from databases containing scholarly articles, government-funded  reports, and conference papers published since 2000. We also  interviewed 11 aviation experts concerning the maintenance and repair of  composite materials in airplanes. These experts represented a variety of  perspectives, including those of manufacturers, repair stations, academic  researchers, and air carriers. We selected these experts based on criteria  related to experience and knowledge in the use of advanced composite  materials in airplanes, specifically in the area of repair and maintenance  of composite materials. To identify FAA’s actions to address these  concerns, we reviewed FAA documents, our reports, and Department of  Transportation Office of Inspector General (DOT IG) reports and spoke  with agency officials and outside experts. (See app. I for more information  on our objectives, scope, and methodology.)
We conducted this performance audit from May 2010 to September 2011  in accordance with generally accepted government auditing standards.  Those standards require that we plan and perform the audit to obtain  sufficient, appropriate evidence to provide a reasonable basis for our  findings and conclusions based on our audit objectives. We believe that  the evidence obtained provides a reasonable basis for our findings and  conclusions based on our audit objectives.
subsections: section_title: Background
paragraphs: Airplane manufacturers have been using composite materials in general  aviation and military applications 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  (e.g., panels). In 1988, Airbus introduced the A320, the first airplane in  production with an all-composite tail section—including the horizontal and  vertical stabilizers and rudder—and, in 1995, the Boeing Company  introduced the Boeing 777, also with a composite tail section. (See fig. 1.)  More recently, manufacturers have extended the use of composites to  airframe structures, such as the fuselage and wings. For example, in  2007, Airbus introduced the A380, which used composite materials in the  wings and upper fuselage. Airplane manufacturers have increased their  use of composites for a number of reasons. First, composite materials  tend to have a higher strength-to-weight ratio than metals, allowing  airplanes to be lighter. And because these airplanes are lighter, they offer  fuel savings, which are a high priority for air carriers. In addition, the  material properties of composites make them more resistant to fatigue  and corrosion than metal, which leads to lower maintenance costs.
The increase in composite materials has been facilitated by private and  federally funded advanced materials research. Although airplane  manufacturers conduct the bulk of the aerospace research on composite  materials as part of their product development activities, over the years,  federal research has contributed to the state of knowledge about  composite properties, and federal research centers have studied basic  and advanced properties of composite materials as well as their  applications. For example, the Department of Defense’s Air Force  Research Laboratory has made significant contributions in materials  research in developing composite aircraft such as the B-2 bomber and  the F-22 fighter. The National Aeronautics and Space Administration  (NASA) has conducted both fundamental research and applied composite  research since the 1970s and 1980s, when it explored the basic  properties of advanced composite materials and in-flight service and  environmental exposure of composite components. More recently, NASA  began funding research on the aging and durability of aircraft advanced  structural materials including composites. FAA funds aviation safety  research programs to support its certification and regulatory activities,  encompassing a range of topics such as fire safety, crashworthiness, and  aging airplanes. For example, it has used its fire test facilities to conduct  tests of composite airplane sections to determine whether the fires will  emit toxic gas that exceeds safety levels. Since 2003, FAA has  collaborated with selected universities in support of its advanced  materials research program. The goal of the project is to provide research  and training in support of expanding composite applications, which the  universities facilitate by partnering with local aviation manufacturers and  suppliers.
Boeing’s 787 will be the first mostly composite large transport airplane in  commercial service. The 787 is about 50 percent composite by weight  (excluding the engines). (See fig. 2.) The 787 is the first large commercial  transport category airplane to use composite materials for much of its  fuselage and wings. As airplane manufacturers are required to do for all  new airplane designs, Boeing applied to aviation regulators in the  jurisdictions where the airplane will be registered to certify the airplane  design. According to Boeing, the fuselage and wing structures require  more extensive certification work than other structures of the airplane.
Boeing applied to FAA for certification of the Boeing 787 in March 2003  and began the certification flight test program in April 2010. Although its  certification application originally called for delivering the first airplanes for  service in 2008, Boeing requested that FAA extend its certification  application four times because of delays caused by development  processes and production challenges. As of September 2011, Boeing had  about 800 orders for the 787 and plans to deliver the first 787 to Japan’s  All Nippon Airways in the third quarter of 2011. In August 2011, Boeing  completed all required flight testing and received type certification from  FAA. The significance of type certification is explained later in this  section. Boeing also is developing a derivative version of the 787-8  model—the 787-9 is a stretch version that will have more seating capacity  than the original version.
Ensuring the safety of the nation’s aviation system is the shared  responsibility of FAA and the aviation industry. FAA is responsible for,  among other things, setting certification standards and certifying that the  airplane manufacturers and parts suppliers meet FAA standards,  conducting periodic inspections of manufacturing facilities to ensure  continued compliance with regulations, and overseeing airplane repair  facilities to ensure they follow the proper maintenance and training  procedures. Airplane manufacturers are responsible for showing  compliance with those regulations and building safe airplanes.  Manufacturers help ensure their airplanes remain airworthy throughout  their designed service life by developing airplane maintenance programs  and repair manuals and providing requested on-site technical assistance.  Airplane operators are responsible for maintaining and operating  airplanes safely and helping maintain the airworthiness of their airplane  fleets by tracking their airplanes’ service history and reporting relevant  repair and accident data to FAA and the manufacturers.
A domestic airplane manufacturer must seek and FAA must issue a type  certificate before a new airplane design is introduced into service. A type  certificate signifies that airplanes manufactured to conform to the basic  airplane and systems design will meet FAA’s airworthiness, noise, and  emission standards for the safe conduct of flights. The standards form the  basis for certification, modified as appropriate in accordance with special  conditions, exemptions, and equivalent level of safety findings. Airplanes  produced under a type-certified design are issued a standard  airworthiness certificate. During the certification process, FAA engineers,  designees, and test pilots review detailed plans, drawings, compliance  plans, test reports, and analyses provided by the manufacturer to  demonstrate the airplane’s compliance with FAA’s safety standards.  (See fig. 3.) For example, the certification plan for the 787-8 contains 13  individual plans relating to structural components of the airplane, with a  total of 904 deliverables from Boeing for FAA approval. During the  certification process, the manufacturer must also produce a prototype (or  prototypes) of the new airplane and conduct both ground and flight tests.
FAA approves newly manufactured airplanes for service by issuing an  airworthiness certificate. Typically, airplanes with a type-certified design  are produced under an FAA production certificate and FAA will issue a  standard airworthiness certificate for each airplane manufactured.  Alternatively, airplanes manufactured without a production certificate will  be issued an airworthiness certificate on a case-by-case basis through  inspection of each airplane to ensure that it conforms to its type design  and is in condition for safe flight.
As part of the type certification process, FAA evaluates the airplane’s  design for novel features and the applicability of airworthiness standards  to ensure that the novel airplane features comply with applicable  performance standards or safety levels. When it finds technical issues  that need further investigation, FAA creates an issue paper to document  issues and communications with the airplane manufacturer. In some  cases, FAA may exempt the manufacturer from an airworthiness standard  when the manufacturer petitions FAA for an exemption and indicates the  exemption is in the public interest and will not adversely affect safety. In  other cases, FAA may approve an equivalent level of safety finding. A  manufacturer requests an equivalent level of safety finding from FAA  when the manufacturer determines that it cannot show literal compliance  with a regulatory standard or when the standard assumes a particular  compliance method that is not feasible for the new airplane design, but  can demonstrate that it meets the same level of safety. FAA also may  determine that an existing standard is not adequate for a novel design  feature, such as when a standard assumes a level of performance based  on traditional materials (e.g., aluminum) and the new airplane design  utilizes different materials. In such situations, FAA may create special  conditions that the manufacturer must meet in order to demonstrate that  the airplane meets the current safety level. Special conditions differ from  an equivalent level of safety finding in three ways: FAA (as opposed to  the manufacturer) originates the action based on a novel design feature,  FAA determines that the regulatory standard is not adequate, and FAA  generally publishes the draft special conditions for public comment.  However, FAA uses the issue paper process to document its evaluation  of technical issues in both situations.
FAA conducts the assessment process for all certification applicants and  creates special conditions when necessary. (See fig. 4.) Prior to  developing special conditions, FAA must determine that the following  criteria are met: (1) The airplane has a novel or unusual design feature,  (2) the airworthiness standards do not contain adequate or appropriate  safety standards for this feature, and (3) the proposed special conditions  establish a level of safety equivalent to that established in the regulations.  Special conditions are unique to the specific certification program in which  they are issued and apply to derivative airplane models—later versions of  that airplane that incorporate similar novel design features.
Airplane manufacturers in the United States may apply for certification of  new airplanes from foreign aviation authorities, which are responsible for  ensuring that airplanes registered in their countries meet their  airworthiness standards. For example, U.S. manufacturers apply to EASA  for approval to allow their airplanes to fly in European airspace. This is  essential for the commercial success of airplanes that are marketed  globally. Boeing applied to EASA for certification of the 787 in 2003.  Aviation authorities often use validation, a form of certification, to  establish compliance for airplanes designed outside their countries and to  issue a type certificate for these airplanes. For example, FAA officials  stated that the European Union, Canada, Japan, and Brazil do type  validations for U.S. aviation products. According to FAA officials, Boeing  has applied for type validation of the 787 with EASA, the Japanese Civil  Aviation Bureau, Transport Canada Civil Aviation, and the Chinese  aviation authority. FAA uses its bilateral airworthiness agreements with  other countries to determine its responsibilities during validation for U.S.  aviation products sent abroad.
FAA and EASA have agreed to coordinate their certification and  validation efforts while recognizing each agency’s authority to develop  and enforce its own standards. In order to promote efficiency, FAA and  EASA established a validation process for issuing type certificates for  airplanes designed in each other’s jurisdiction. FAA is the primary  certificating authority for U.S.-manufactured airplanes, and EASA is a  validating authority. EASA and FAA reverse roles for airplanes  manufactured in the European Union. Under the defined procedure, the  primary certificating authority takes the lead role in working with the  manufacturer while the validating authority remains involved. FAA and  EASA also recognized the importance of effective, continual  communication among themselves and the manufacturer to facilitate this  process.
FAA plays a significant role in ensuring the continued safe operation of in- service airplanes. The agency accepts new airplane maintenance  schedules and manuals, inspects repair stations to ensure quality  assurance standards are met, and issues directives when it detects  problems. As part of airplane type certification, FAA accepts the  manufacturer’s airplane maintenance schedules, which become the basis  upon which air carriers develop their own maintenance programs. FAA  certifies and oversees repair facilities’ safety and operations. These  facilities, which include independent repair stations (part 145 facilities)  and airline in-house repair facilities (part 121 operators), conduct airplane  repairs and maintenance in accordance with airworthiness standards and  manufacturers’ requirements. As part of its oversight activities, FAA  checks whether these facilities are using qualified staff as well as whether  facilities are following their maintenance, repair, and training programs.  Finally, FAA issues airworthiness directives—orders directing corrective  action to maintain airworthiness—when it becomes aware of an unsafe  condition with an airplane and determines that the condition is likely to  exist or develop in other airplanes of the same design.
section_title: FAA Followed Its Special Conditions Process in Requiring That Boeing Demonstrate That the 787’s Composite Structures Meet Existing Safety Levels
subsections: section_title: FAA Established Special Conditions for Boeing to Demonstrate That the 787’s Composite Airframe Meets Existing Safety Levels
paragraphs: FAA applied 5 special conditions where it determined the applicable  airworthiness regulations did not contain adequate or appropriate safety  standards for design features related to the 787’s composite fuselage and  wings. Two of the 5 special conditions are concerned with occupant  survivability in a postcrash scenario, and 3 of the 5 relate to the  soundness of the fuel tank structure in order to prevent fuel leakage or  ignition. (See table 1.)
These 5 special conditions, which relate to novel features of the airplane’s  composite fuselage and wings, represent a third of the 15 special  conditions that FAA created as part of its overall certification of the 787  airplane. Initially, the special conditions are applicable to the 787-8 model.  If FAA amends the type certificate for the 787 at a later date to include  derivative models that incorporate similar novel design features, the  special conditions would apply to the other models as well.
section_title: FAA Followed Its Processes for Developing and Monitoring Special Conditions
paragraphs: On the basis of our review of FAA’s documentation and discussions with  FAA officials about its activities in developing the five special conditions,  we found that FAA followed the special conditions process. Specifically,  we found that FAA identified and evaluated technical issues and  regulatory standards, determined the need for special conditions,  obtained and responded to public comments, and monitored Boeing’s  compliance activities. In August 2011, FAA issued the type certificate for  the Boeing 787.
Identifying technical and regulatory issues: FAA evaluated  technical issues related to the composite feature, identified regulatory  standards that may not be adequate, consulted with technical and  scientific experts, and documented Boeing’s position. FAA  documented its evaluation of the airplane’s design issues and gaps in  the regulatory standards. For example, FAA developed the tire debris  penetration special conditions because the regulation, which was  based on the assumption that the wings would be made from  aluminum, specifies that only the fuel tank access panels need be  resistant to debris penetration rather than the entire wing area.  However, FAA’s certification staff determined that Boeing needed to  demonstrate that the entire wing, and not just the fuel tank access  panels, be able to withstand debris. We also found sufficient evidence  that in developing each of the special conditions, FAA involved  technical specialists and, in some cases, relied on research done at  its technical research center. For example, FAA used the results of  the technical center’s research on appropriate test methods for  demonstrating the fire resistance of composite fuselage materials to  help it develop its special conditions. In another case, we found that  FAA also reviewed test results provided by Boeing as it evaluated the  technical issues.    Determining special conditions were needed: We found that,  consistent with FAA policy, FAA adequately documented the  implications of the composite features on safety, why the existing  airworthiness standards were not adequate, and how the special  conditions would enable the 787 airplane to meet the current level of  safety. For example, FAA staff noted that the current fuel tank fire  resistance standards do not explicitly require that the areas  contiguous to the fuel tank access panels be resistant to tire debris  because the standards were based on the performance of aluminum  wings. The ability of aluminum wing skins to resist penetration by  debris is understood from extensive use. However, lacking an  extensive service history of composite wings, FAA determined that  Boeing would have to take additional steps to prove that the wing  surface area contiguous to the fuel tanks meets the current safety  level. We also found that FAA obtained Boeing’s position on the  proposed special conditions and reviewed Boeing’s plans for  demonstrating compliance. In some cases, FAA and Boeing  negotiated certain aspects of the compliance approach. Before each  proposed special condition was issued for public comment, the parties  tentatively agreed on the compliance approach and what Boeing  would deliver (e.g., test plans, test report, or analyses) to demonstrate  compliance.    Public comment: We found that before finalizing each of the five  special conditions, FAA solicited and considered public comments by  publishing the draft special conditions in the Federal Register. FAA  summarized the source and substance of each comment received  and the agency’s position on the substance of the comments in the  final special conditions, which are publicly available. FAA did not  revise the special conditions on the basis of the comments, although it  could have done so had it determined that revision was advisable. As  part of our review of the public comments, we took steps to gather  additional information about technical issues. For example, we  contacted one of the two parties who commented on the structural  lightning protection special condition to obtain technical information  and discussed these issues with FAA.    Monitoring compliance: We found that FAA tracked the status of the  deliverables Boeing provided in order to determine that the  manufacturer complied with the special conditions and was  demonstrating that it could meet safety levels. We found that FAA  tracked the dates each deliverable was received and approved. For  most deliverables, FAA staff, rather than a designee, was responsible  for approving the deliverable, especially for more significant tests and  documents. As noted above, tests were among the various forms of  deliverables. Although FAA designees were the responsible officials for  witnessing the certification tests, Boeing representatives invited FAA  staff to observe the tests as well, and FAA staff attended many of them.  Boeing tested full-scale structures, such as a portion of the wing span,  the horizontal stabilizer, and the fuselage. Some of these tests were  conducted to simulate how certain composite structures would perform  in a crash. One such test, which FAA technical staff monitored, involved  vertically dropping a section of a composite fuselage from a height and  at a rate that FAA required. The test validated the analytical model  used to assess the behavior of the 787 fuselage for all the design  conditions required under the special conditions.
section_title: FAA Revised Its Fuel Tank Lightning Protection Requirements during the 787 Certification Process
paragraphs: FAA’s review of the 787 airplane design and determination of special  conditions occurred as the agency was reconsidering changes it had  previously made to the fuel tank lightning protection standards. In 2001,  FAA amended its fuel tank ignition regulations to address the causes of a  1996 catastrophic fuel tank explosion accident. FAA’s new approach to  precluding fuel tank explosions required reductions in both the probability  of ignition sources occurring in the fuel tanks and the flammability of fuel  tanks. Compliance with this approach required an airplane manufacturer  to demonstrate its airplane design has three highly reliable, independent,  and redundant protective features to prevent ignition sources or has two  such design features that are continuously monitored or routinely  inspected. However, by 2006, several certification applicants found it  impractical to meet the revised design standards for fuel tank structure as  applied to the lightning protection features. For example, applicants  indicated that it was impractical to routinely inspect protective features  inside the fuel tank because fuel tank inspections may occur only once or  twice in the life of an airplane and more frequent inspections could result  in damage to lightning protection features during the inspection process.  FAA officials noted that the agency had not realized that airplane  manufacturers would find it impractical to comply with the revised  requirements when it developed them. However, after it had granted  partial exemptions to two airplane certification applicants and was in the  process of evaluating the 787 design, FAA determined that it needed to  provide additional policy guidance while it studied the issue further.
In 2009, FAA issued guidance that established the circumstances under  which the agency may create special conditions for fuel tank lightning  protection for manufacturers of airplanes with composite fuel tanks and  grant exemptions to manufacturers of airplanes with aluminum fuel tanks.  It identified requirements and indicated that it will develop methods of  compliance whenever it creates special conditions or grants an  exemption. In each case, FAA will approve a design if it finds that the  proposed design would provide an acceptable level of safety. According  to the policy, new airplane designs must include technology that reduces  flammability, such as a nitrogen generation system, in fuel tanks that are  more flammable than typical aluminum wing fuel tanks. Prior to issuing  this policy, FAA provided a draft version for public comment, which  generated a large number of comments from a variety of stakeholders  (e.g., airplane manufacturers, aviation manufacturing associations, and a  union representing FAA engineers, among others). FAA wrote a  response to each of the comments it published and incorporated changes  to its policy as it deemed appropriate. Some comments were technical  corrections. Others were more substantive. For example, two parties  providing comments questioned whether FAA should allow airplanes to  be operated when their fuel tank flammability reduction systems are  inoperable, noting that these systems are one of the redundant systems  necessary for preventing fuel tank fires during a lightning strike. FAA  responded that the issue is not part of the structural lightning policy, but  lightning policy, but noted that the decision is made by the FAA flight  operations board on a case-by-case basis.
section_title: FAA Granted an Equivalent Level of Safety Finding Related to the Composite Fuselage
paragraphs: In addition to creating the special conditions, FAA granted Boeing an  equivalent level of safety finding for the 787 related to the flame  penetration properties of the fuselage. As indicated, an airplane  manufacturer can request an equivalent level of safety finding when it  determines that it may not be able to comply literally with the standard,  but it can show that its airplane design meets the same level of safety. In  this case, Boeing proposed demonstrating that the 787 composite skin  and insulation configuration could meet the current level of safety  developed for typical aluminum-skin and insulation configurations. Boeing  proposed using a large-scale or laboratory-scale test—that is, a different  test method from the small-scale test that the standard specifies for  applicants to simulate the characteristics of a postcrash fire. Boeing  determined that a small-scale test would not be sufficient for testing its  composite fuselage fire resistance properties because the standard FAA  test does not test the airplane skin, which the regulation assumes to be  aluminum. FAA approved the equivalent level of safety finding subject to  the condition that the results of Boeing’s large-scale (or laboratory-scale)  testing show the 787 fuselage skin and structural components provide a  survivable cabin environment for 5 minutes or equivalent to that of a  traditional aluminum fuselage with compliant insulation. We also found  that FAA documented its determination to grant Boeing an equivalent  level of safety finding, providing a description of the technical issues and  Boeing’s plan to demonstrate the composite fuselage would meet the  current level of safety in a manner similar to how it documented the  special conditions determination, although it did not obtain public  comments, which are not required for an equivalent level of safety finding.
section_title: EASA Also Assessed the Use of Composite Materials in the Boeing 787
subsections: section_title: EASA’s Process Is Similar to FAA’s Special Conditions Process
paragraphs: EASA uses a validation process (a form of certification) to issue a type  certificate indicating that U.S.-manufactured airplanes meet European  airworthiness standards. As with FAA, during validation EASA develops a  certification basis comprising relevant airworthiness standards and  additional considerations such as special conditions to account for novel  features or new uses of products. FAA and EASA officials stated that the  two authorities work together to harmonize their standards and, as a  result, the standards are similar in many respects, but have some  differences. For example, one authority may adopt a standard before the  other. As with FAA’s certification process, a key component of EASA’s  type certification is determining whether current airworthiness standards  are appropriate to ensure an airplane’s novel features or new product  uses meet current levels of safety. EASA develops a certification review  item (review item) when it identifies an airworthiness standard that may  not be adequate for addressing novel features or new technology uses.
As part of its validation review, EASA identifies technical and regulatory  issues that it wants to evaluate further and discuss with the manufacturer  and creates what it calls action items to document these actions.  According to EASA, the agency develops review items by reviewing  current standards and guidance material, considering its and the  manufacturer’s experience with existing technology, and determining  possible ways to show relevant performance of new technology or  specifying new requirements. Review items can result in special  conditions, means of compliance, or equivalent safety findings that  become part of an airplane’s certification basis. Review items contain a  description of the technical or regulatory issues, EASA’s position, and any  requirements and conditions the manufacturer must meet for certification.  According to EASA officials, when EASA and the manufacturer agree to  the conditions and requirements contained in the review items, EASA  closes the review item.
section_title: EASA Created 11 Review Items Associated with the Boeing 787’s Composite Airframe
paragraphs: According to EASA, it developed 11 review items—resulting in seven  special conditions and five means of compliance—to address existing  EASA airworthiness standards it determined were not adequate for  determining whether the 787’s composite fuselage and wings met current  levels of safety. These review items focus on issues such as  crashworthiness, fatigue and damage tolerance, structural integrity, fire  resistance, and fuel tank protection. (See tables 2 and 3.) The purposes  of the 11 review items include to enhance knowledge of and bring  attention to issues related to composites, to address new or novel  features of composites, to apply newly developed airworthiness  standards, and to address new methods of compliance with airworthiness  standards. In order to receive its type certification from EASA, Boeing  must demonstrate compliance with the conditions and requirements  contained in special conditions and means of compliance identified in the  EASA review items.
We found that 5 of EASA’s composite-related review items resulted in  special conditions that are similar to the special conditions and equivalent  level of safety finding that FAA developed for the 787. (See table 2.)  Specifically, four of these special conditions—fuselage crashworthiness,  wing and fuel tank fire protection, fuselage in-flight fire resistance, and  fuel tank protection from debris—are very similar to four of FAA’s special  conditions. The postcrash fire resistance special condition is similar to  FAA’s equivalent level of safety finding, but it adds a requirement that  FAA did not include. EASA required that Boeing provide safety  information for rescue crews in case of a fire emergency.
We found that the remaining 6 EASA review items differed from FAA’s  special conditions and equivalent level of safety finding. (See table 3.)  EASA created these review items to address differences between its and  FAA’s airworthiness standards, regulatory language, interpretations of  standards, and positions on technical issues. For example, EASA  developed its review item on the structural integrity of fuel tank access  covers to apply a standard that already existed for FAA. For other  review items, EASA’s regulatory language differed from FAA’s (fuel tank  flammability), and EASA requested information from Boeing about the  composite materials’ strength and damage tolerance that FAA did not  request (performance of composites on the fin deck).
The extent to which EASA relied on FAA to oversee and determine  Boeing’s compliance with EASA’s composite-related review items varied.  According to EASA officials, EASA requested that FAA determine  compliance for a majority of the requirements (i.e., deliverables) identified  in the review items and action items. EASA validated the 787’s type  design in August 2011, requiring an FAA statement of compliance prior to  issuing its type certificate. Three of EASA’s review items indicated that  EASA requested that FAA determine whether Boeing complied with the  airworthiness standards included in the review items. In one review item,  EASA retained the compliance determinations. The remaining seven  review items did not directly indicate which agency would determine  compliance, although EASA indicated in three of the seven that it will  remain involved by reviewing supporting documentation. Additionally,  throughout its development of the review items, EASA reviewed  documentation and test results and analysis from Boeing as well as  witnessed Boeing-conducted tests.
section_title: FAA and Industry Actions May Address Key Safety-Related Concerns, but It Is Too Early to Assess the Adequacy of These Actions
subsections: section_title: Key Safety-Related Concerns Identified in Areas Related to Composite Airframe Repair and Maintenance
paragraphs: Through a review of relevant literature and interviews with experts, we  identified and categorized key safety-related concerns into four areas,  namely (1) limited information on the behavior of composite airframe  structures, (2) technical concerns related to the unique properties of  composite materials, (3) limited standardization of composite materials  and repair techniques, and (4) level of training and awareness on  composite materials. As we have previously reported, problems with  repair and maintenance can affect the safety of airplane operations.  None of the experts that we spoke with felt that the concerns they  identified posed extraordinary safety risks or were insurmountable.  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.
Limited information: These concerns focus on how composite airframe  structures behave when damaged and as they age. These concerns are  partly attributable to the limited in-service experience with composite  materials used in the airframe structures of commercial airplanes and,  therefore, less information is available on the behavior of these materials  than on the behavior of metal. Studies that we reviewed noted that more  empirical data would help better predict the behavior of damaged  composite structures through more robust models or analytical methods.  Reliable damage behavior predictions are important because they help  form the basis for a new airplane’s design or maintenance program. An  expert that we spoke with also noted that while manufacturers rely, in  part, on models to predict the behavior of damaged composites, the  limited amount of in-service performance data available to use as inputs  to the models may create challenges for airplane designers.
Technical concerns: These concerns include challenges in detecting  and characterizing damage in composite structures, as well as making  adequate composite repairs. Impact damage to composite structures is  unique in that it may not be visible or may be barely visible, making it  more difficult for a repair technician or aviation worker to detect than  damage to metallic structures. In addition, the type of nondestructive  inspection techniques repair technicians could use to detect and  characterize composite damage varies, in part because composites  vary in their construction (e.g., sandwich composite construction and  variable thicknesses of laminate construction). The ability of composite  nondestructive inspection techniques to adequately detect damage  depends on the composite’s construction and the type of damage (e.g.,  delamination, disbonding, or water infiltration). Thus, damage may not  be detected sufficiently or properly if repair technicians do not use or  apply the correct nondestructive inspection technique. Furthermore, no  nondestructive inspection technique exists that can measure the strength  of a bonded composite repair after it is completed. Making a repair is also  a concern partly because composite repairs are more susceptible to  human error than metal repairs since the quality (i.e., achieving the  anticipated strength) of a composite repair is highly dependent on the  process used.
Limited standardization: Composite materials and repair techniques are  less standardized than metal materials and repairs. With limited  standardization due, in part, to business proprietary practices and the  relative immaturity of the application of composite materials in airframe  structures, a repair technician could confuse materials or processes,  which may result in improper repairs. According to one study, only about  a dozen common metal alloy materials are used for traditional metal  repairs, while over 60 unique materials may be used for various  composite repairs. Less standardization also can have a negative  economic impact for airlines and repair stations because a repair facility  might have to keep a large stock of repair materials and parts in house,  which creates an inventory and storage challenge. Composite materials  generally need to be stored at a specific temperature, and the materials  also have shelf lives (i.e., expiration dates).
Level of training and awareness: This concern focuses on whether  industry workers handling composites or in contact with composites  (specifically, repair technicians, designees, and airport workers) and FAA  aviation safety inspectors receive sufficient training and are aware of and  can appreciate the differences between metal and composite materials.
Airplane repair technicians and designees that have worked with metal  materials for decades generally may not be as familiar with composite  materials, whose application in airplanes is relatively recent and whose  unique characteristics are associated with technical challenges. Two  experts suggested that applying metal repair practices to composite  structures may be inappropriate and risk the repair of the composite  structures. Thus, repair technicians and designees need adequate  training about composites’ unique characteristics and the associated  challenges to—in the case of repair technicians—properly maintain and  repair composite structures and—in the case of designees—properly  review and approve composite repair designs. FAA requires that part  121 certificate holders (air carriers), their agents, and part 145 repair  stations (independent repair facilities) have training programs that are  adequate to ensure that personnel approving and performing composite  inspections, maintenance, and repairs are informed and competent to do  so. One expert expressed concern that while the training is available to  technicians and designees, they may lack incentives to become trained.  Four experts suggested that FAA or industry implement certification  requirements for technicians that work with composite structures, similar  to that of welders.
Airline and airport workers also may require greater awareness of the  differences in the damage properties of composite materials and metallic  materials. Ramp areas at airports are typically small, congested areas  where departing and arriving aircraft are serviced by airline and airport  ramp workers, including baggage, catering, and fueling personnel. As we  have previously reported, a large number of people using equipment in a  relatively small area, often under considerable time pressure, creates an  environment in which aircraft and equipment can, among other things, be  damaged. Undetected aircraft damage from ramp activities, whether to  metallic or composite structures, can cause in-flight emergencies. In  December 2005, for example, an Alaska Airlines MD-80 that had  departed from Seattle for Burbank, California, experienced a sudden  cabin depressurization. After the aircraft safely returned to Seattle, it was  discovered that a ramp vehicle had punctured the aircraft fuselage, but  the incident had not been reported.
FAA’s aviation safety inspectors may not have sufficient composite- related training or knowledge to identify safety risks during inspections,  according to some experts with whom we spoke. As part of FAA’s  oversight process, FAA aviation safety inspectors check airlines’ and  repair stations’ processes and programs, including whether their facilities  are following their respective maintenance, repair, and training programs.  While FAA does not actually inspect or check the quality or strength of  composite repairs, according to FAA officials, FAA inspectors should be  knowledgeable enough about composite structure maintenance and  repair so that they can identify safety problems at repair facilities. For  example, one expert noted that FAA inspectors need to be able to identify  whether repair technicians are using the appropriate nondestructive  inspection technique or interpreting the results correctly. Three experts  suggested that FAA inspectors should complete a required level of  composite-related training or certification prior to inspecting facilities that  handle composites. Furthermore, the demand for FAA inspectors that  have sufficient knowledge in composites may increase with the growth of  in-service airplanes with composite airframe structures needing  composite maintenance and repair.
section_title: FAA Has Actions Intended to Address Key Safety- Related Concerns
paragraphs: FAA has ongoing or planned efforts that are intended to help address the  areas of safety-related concerns that we identified. Because FAA  regulations and oversight activities are not specific to composites,  however, FAA’s actions to address these concerns are within its current  roles and responsibilities. Many actions are similar to actions it takes for  certifying and overseeing the continued airworthiness of any new  airplane, but are adapted to address the unique characteristics of  composite materials. FAA’s efforts to address these concerns include  issuing new or modified guidance and policy, conducting research,  developing and implementing training, and collaborating with industry  stakeholders. As discussed below, each of these efforts relates to  multiple safety concerns that we identified.
Guidance and policy: FAA recently has updated guidance and has  proposed additional guidance related to composites, which helps address  concerns related to training and awareness, technical areas, and limited  information. For example, FAA updated its existing guidance on  composite aircraft structure, and on quality systems for composite  manufacturing. This updated guidance helps address technical  concerns by providing information on composite materials to  manufacturers designing and seeking certification of new airplanes. FAA  is currently updating guidance on composite and bonded aircraft  structures, which will be targeted toward all facilities that conduct  composite repairs and alterations. This guidance helps address both  training and awareness concerns and technical concerns by providing  information on composite repair. FAA also has draft guidance to help  entities that handle composite materials develop training or qualification  programs for composite maintenance technicians. And, while the rule is  not focused on composites, FAA recently issued an airplane fatigue  damage rule, which helps address concerns related to limited  information on how composite structures age and fatigue. The rule  requires that all manufacturers take a proactive approach to managing  risk related to widespread fatigue damage by requiring the demonstration  of the validity of the structural maintenance program by test or service  experience, in an effort to reduce FAA’s current practice of issuing  airworthiness directives after an incident.
Research: FAA has past, ongoing, and planned research related to the  inspection and repair of composites, as well as research on aging  airplanes. FAA’s research helps address concerns about limited  information on how composite airframe structures behave when damaged  and as they age, technical concerns, and standardization concerns. FAA  partners with universities under its Centers of Excellence program,  conducts research at its Technical Center, as well as contracts with  industry and academia. For example, FAA’s National Aging Aircraft  Research Program, which was initiated following passage of the Aviation  Safety Research Act of 1988, includes research on the maintenance  and repair of airplane structures, including composite structures and how  they age. Part of this research is conducted under FAA’s Centers of  Excellence program. FAA’s research efforts have produced information  about airplane design guidelines, which FAA then incorporates into its  industry guidance discussed above. FAA’s collaboration with academia  and industry also provides research on standardizing materials and  processes.
Training: FAA offers a composite materials training course for its aviation  safety inspectors and is developing another composites awareness  course for designees, which addresses concerns related to training and  awareness and technical issues. In 2009, this course replaced two  previously offered composites training courses for FAA inspectors. In  developing the current course, FAA utilized new terminology and industry  input for the new curriculum to design the course around the inspection of  new-generation composite airplanes. Also, according to an FAA official,  this course focuses more on an inspector’s job functions in performing  audit and surveillance activities of composite maintenance facilities, while  the prior classes were not tied back to regulations or surveillance  activities. Similar to other technical courses available to FAA inspectors  who oversee maintenance activities, this course is available to those who  need it. FAA officials explained that the course is not required for all such  inspectors because only selected inspectors are assigned to facilities that  perform composite repair; thus, not every inspector needs to complete the  course. FAA field office managers are responsible for requesting this  course for their staff and use FAA’s formal decision tree process to  determine if the inspector needs the training. FAA officials reported to us  that, based on FAA training request records for the past 3 years, all  requests made by field office managers for inspectors to receive the  composites awareness training have been fulfilled. According to FAA’s  internal order on inspector training, conditions, including completion of on- the-job training, must be met for an inspector to perform tasks  unsupervised. FAA officials explained that many inspectors have gained  experience with composite materials before being hired by FAA, and that  field office managers who keep track of inspectors’ training and skills do  not assign aviation safety inspectors to tasks that they are not qualified  for. According to FAA data, 73 percent of FAA inspectors assigned to  repair stations that are certified to conduct composite repairs on large  airplanes have completed one or more of the composites courses. (FAA  was unable to tell us whether these repair stations were actively repairing  composite structures.) Regarding training for airlines and repair stations,  FAA officials told us that these facilities are responsible for training their  own repair technicians or other aviation workers. However, FAA is  currently collaborating with industry stakeholders to help develop and  encourage industry stakeholders to provide composite training.
Industry collaboration: FAA also collaborates with industry stakeholders  and in some cases sponsors industry workshops or working groups. FAA  plays a leadership role in the Commercial Aircraft Composite Repair  Committee (CACRC)—whose charter is to develop and improve  maintenance, inspection, and repair of commercial airplane composite  structure and components. CACRC has several specific task groups that  help address safety-related concerns in several areas that we identified.  For example, CACRC has a task group that focuses on composite  training, as well as task groups that work on issues related to repair  techniques, repair materials, and inspection. In recent years, CACRC  published a document that represents the industry standard for teaching  points for an awareness class on Critical Issues in Composite  Maintenance and Repair. FAA’s composites awareness course for FAA  inspectors discussed above used these teaching points as a foundation  for its curriculum. In addition to its involvement with CACRC, FAA  sponsors working groups that are composed of composite airplane  manufacturers (i.e., Boeing and Airbus) and regulators (i.e., FAA and  EASA) and whose charters include identification of maintenance issues.  FAA also sponsors industry workshops to facilitate the sharing of  information, such as technical issues related to damage tolerance or  standardization of composite materials. According to FAA, these working  groups and workshops help address concerns related to technical issues,  standardization, and training and awareness. Furthermore, FAA’s  technical center sponsors the Composite Material Handbook 17, which  provides information and guidance to industry stakeholders, such as  databases and educational materials for structural engineering,  maintenance, and manufacturing, that helps address technical concerns  and to some degree concerns about standardization.
section_title: Industry Stakeholders Play a Role in Addressing Safety-Related Concerns
paragraphs: Industry stakeholders—mainly manufacturers and airlines—also play a  significant role in ensuring an airplane’s continued safety and have taken  a range of actions that help address concerns that we identified. Because  our study focused on FAA actions to address key safety-related concerns,  the actions discussed here should not be considered all-inclusive.  Manufacturers are responsible for designing and building airplanes that  are safe and meet safety standards, and providing instructions for  continued airworthiness that are accepted by FAA. Furthermore,  manufacturers are generally expected by their customers (i.e., airlines) to  design an airplane that is maintainable and reparable, as well as to  support repair and maintenance of airplanes in service. Airlines are  responsible for the safe maintenance and operation of airplanes. Actions  taken by manufacturers and airlines that help address concerns include  manufacturers’ direct customer service support to airlines, research and  design allowances, involvement in programs to share data on in-service  airplanes, training, and participation in industry groups and FAA- sponsored working groups and workshops.
Specifically, manufacturers have conducted and continue to conduct  extensive research on composites as part of their product development  activities. According to Boeing representatives, a significant number of  tests are conducted during the design development stage to gain  knowledge about the materials and the structures used and verify that  they will behave as predicted. Through the design development and  certification process, manufacturers incorporate safety allowances and  redundancies into the airplane design, helping address concerns related  to limited information and technical concerns. For example, a  manufacturer may design an airplane that is strong enough to ensure that  nonvisible damage that may occur to a composite fuselage would not  require structural repair to maintain structural integrity and airworthiness.  Also, when preparing repair instructions for a structural repair manual, a  manufacturer may use its research conducted on repair techniques to set  allowable limits on the size or type of a composite repair to ensure that  the repair does not diminish an airplane’s strength below the acceptable  airworthiness level.
Airlines, through their relationships with the manufacturers, may provide  manufacturers with service information, such as selected maintenance  records, that help increase an airplane’s maintainability and reparability.  These relationships help address limited information and technical  concerns by providing service information to the manufacturer to  incorporate into maintenance and repair instructions and future airplane  designs. Service information provided by airlines is also analyzed by  manufacturers and incorporated into service bulletins and service letters  that provide new or modified information on how to maintain and repair an  airplane, which helps airlines become educated about any new technical  issues. In addition, airlines may participate in a focused fleet survey  program with the manufacturer, which involves an airline and  manufacturer conducting more detailed evaluations of in-service  airplanes. This information can be incorporated into maintenance and  repair plans and help provide insights to improve future airplane designs.
We also found that to help address training and awareness concerns,  manufacturers and airlines provide training on composites. For example,  Boeing currently offers four courses to its Boeing 787 customers  specifically related to composite structures. Boeing reported that, on the  basis of enrollment so far, it anticipates that all of the airlines purchasing  the 787 will send some personnel through one or more of its composites  courses, which is almost twice the participation of similar courses for  previous airplane programs. Major airlines may also provide in-house  training to their personnel.
As discussed above, industry representatives, including manufacturers  and airlines, voluntarily participate in CACRC activities and FAA- sponsored working groups and workshops to share information globally.  Their participation in these groups helps address concerns in several  areas that we identified. Specifically, the workgroups provide a venue to  share lessons learned about repair and maintenance and for  manufacturers and airlines to discuss needs and goals for  standardization.
section_title: It Is Too Early to Fully Assess the Adequacy of FAA and Industry Actions
paragraphs: It is too early to fully assess the adequacy of FAA 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. As discussed previously, manufacturers are  increasingly using composite materials in the airframe structures of  transport airplanes. As more airlines add airplanes with composite  airframe structures to their fleets, the demand for composite maintenance  and repair will increase. To accommodate that growth, FAA will likely  need to certify and oversee an increasing number of repair facilities,  and more FAA personnel will likely need knowledge and training composites. It is, however, unclear at this time what the extent of the  demand will be on FAA to certify additional repair stations for composites  and on FAA inspectors who would oversee those stations. It is also too  early to determine how well positioned FAA and its inspectors will be to  meet future demands given that several FAA efforts, including in the  areas of composite training and FAA guidance, are in the planning stages  or are only recently under way. Similarly, the adequacy of other FAA and  industry efforts—i.e., research, modeling, and stakeholder relationships,  such as those between manufacturers and airlines, which depend in large  part upon the collection and sharing of maintenance and repair  information—can be fully evaluated only when there is greater in-service  experience with composite airframe structures.
Finally, the extent to which the previously discussed FAA and industry  efforts may help to ensure the continued airworthiness of composite  airframe structures may also be affected by whether and when FAA  addresses broader oversight weaknesses that we and others have  previously identified. In recent years, both we and the DOT IG have  identified weaknesses in how FAA implements its oversight processes,  including the reliability, validity, and completeness of the data FAA uses  to manage safety risks. We did not evaluate these processes during our  review, or the steps FAA is taking or plans to take to address those  weaknesses, because these concerns are not specific to the repair and  maintenance of composite structures. However, the increased use of  composite materials in airplanes may exacerbate some of these  weaknesses—and their associated risks—if FAA does not take  appropriate corrective steps. For example,    As mentioned earlier, composite damage may be less visible, and  consequently more difficult to detect, than metal damage. To the  extent composite damage goes undetected, and thus unreported, it  would diminish the validity, completeness, and reliability of the data  that FAA will be collecting and using to help proactively identify risks  and take actions to mitigate those risks before they result in failure of  composite structures.    Deficiencies in FAA’s oversight systems for airlines and repair stations  affect FAA’s ability to ensure that these facilities have the proper tools  and are following their respective maintenance programs and quality  control processes. For example, the DOT IG has reported that the  design of FAA’s airline surveillance system is flawed in that it allows  lower-risk maintenance programs to be inspected before higher-risk  programs.
section_title: Agency Comments and Third-Party Views
paragraphs: We provided copies of a draft of this report to DOT, NASA, EASA, and  Boeing Company for their review and comment. Each organization  provided technical corrections and clarifications, which we incorporated  as appropriate.
As arranged with your offices, unless you publicly announce its contents  earlier, we plan no further distribution of this report until 30 days after the  date of this letter. At that time, we will send copies of this report to the  appropriate congressional committees, the Secretary of Transportation,  the Administrator of FAA, the Administrator of NASA, and other interested  parties. In addition, this report will be made available at no charge on the  GAO website at http://www.gao.gov.
If you or your staff members have any questions or would like to discuss  this work, please contact me at (202) 512-2834 or dillinghamg@gao.gov.  Contact points for our offices of Congressional Relations and Public  Affairs may be found on the last page of this report. GAO staff who made  key contributions to this report are listed in appendix II.
section_title: Appendix I: Objectives, Scope, and Methodology
paragraphs: This report addresses the Federal Aviation Administration’s (FAA) and the  European Aviation Safety Agency’s (EASA) certification of airplanes using  composite materials, specifically the agencies’ processes for developing  special requirements to ensure that Boeing demonstrates the 787  composite fuselage and wings meet current safety levels, and FAA’s  actions to address safety-related concerns associated with repairing and  maintaining composite airplanes identified by literature and stakeholders.  We focused on FAA’s and EASA’s actions as they relate to the  certification of the Boeing 787 because it is the first large transport  category airplane for commercial use with a composite airframe structure  to undergo the certification process. To address these objectives, we  reviewed FAA and EASA regulations, policies, and processes and Boeing  certification documents for the special conditions and review items the  agencies indicated were related to the 787’s composite fuselage and  wings. We conducted a literature search and reviewed 39 journal articles  and technical papers related to the repair and maintenance of composite  airplanes. We interviewed 11 stakeholders with expertise in the area of  maintenance and repair of composite materials in airplanes and  representing a variety of perspectives, including manufacturers, repair  stations, academic researchers, and air carriers.
subsections: section_title: Review of FAA’s Process to Develop Special Conditions for the 787 Composite Structures
paragraphs: To provide information about FAA’s certification and special condition  processes for the 787, we interviewed FAA and Boeing officials and  reviewed FAA regulations, orders, policies, and other guidance. At the  time of our review, FAA had developed the certification basis for the 787  airplane, which identified the regulatory standards, special conditions,  exemptions, and equivalent level of safety findings that make up the  airplane’s type certification. FAA indicated that it had developed issue  papers for five special conditions, one equivalent level of safety finding,  and five means of compliance (two of which relate to two of the special  conditions) for the standards that it determined did not contain  appropriate safety requirements to ensure that the 787’s composite  fuselage and wings meet the current level of safety and provided  documentation of them. We focused on the special conditions and  equivalent level of safety finding because we were interested in  determining whether FAA followed its process for developing them and  the information was publicly available. We did not conduct a  comprehensive review of all of the airworthiness standards that affect the  composite fuselage or wings nor did we make an assessment of whether  FAA should have created special conditions for the composite features in  addition to those identified by FAA.
On the basis of our analysis of FAA’s processes, we developed a flow  chart of the major steps in the issue paper and special condition  processes. These processes are linked because issue papers may be  used to support a special condition determination, as well as an  equivalent level of safety finding or means of compliance. Using this  information, we created a data collection instrument that allowed us to  review FAA and Boeing’s technical papers and determine to what extent  FAA documented that it followed these steps. In particular, we looked for  information that documented how FAA    determined there was a significant technical or regulatory issue,    determined it should develop special conditions or equivalent level of    obtained and responded to public comments, and    monitored Boeing’s compliance with special conditions.
Following our preliminary review of the documents, we interviewed FAA  officials and Boeing representatives to obtain additional information and  documents to more fully understand the steps FAA took to evaluate the  787 design, regulations, and Boeing’s actions to demonstrate compliance.  Although we reviewed documents describing some of Boeing’s  compliance activities, Boeing’s actions to demonstrate compliance with  the special conditions are considered proprietary, and therefore we were  not able to describe them in detail. As part of our review of the public  comments to the special conditions, we identified technical issues and, in  one case, contacted the source of the comments to obtain additional  information.
section_title: Review of EASA Certification Review Item Process
paragraphs: To provide information about EASA’s validation of the 787’s  airworthiness, we interviewed EASA and FAA officials involved in the  certification process and reviewed relevant EASA documents. EASA  identified 11 certification review items (review items) that it developed  related to the Boeing 787’s primary composite features. We obtained and  reviewed the EASA regulations, principles, and processes concerning  validation, as well as the 11 composite-related review items. We  developed analytical tools to determine the technical or regulatory issues  and the requirements or conditions contained in the review items. We  used the analytical tools to identify the review items’ similarities to and  differences from the composite-related special conditions and equivalent  safety findings that FAA developed.
section_title: Identification of Repair and Maintenance Concerns
paragraphs: To identify the key safety concerns associated with the repair and  maintenance of composite airframe structures in transport airplanes, we  interviewed 11 aviation experts and conducted a literature search and  reviewed 39 documents and FAA technical reports related to the repair  and maintenance of composite airframe structures in transport category  airplanes. Our literature search methodology is discussed below. The 11  experts we interviewed represented a variety of perspectives, including  manufacturers, repair stations, research or academia, air carriers, and  aviation consultants or providers of composite training. As part of our  methodology for identifying experts, we developed a list of categories that  represent the range of entities with involvement in the repair and  maintenance of composite airframe structures in transport category  airplanes. We reviewed background information to identify potential  sources of stakeholders, as well as actual names of experts. We also  reviewed the interviews conducted during design to identify any sources  or names of experts recommended by the interviewees. For the selection  process, we developed criteria and determined that the experts would  have to meet two or more of the criteria to be selected for interviewing.  The criteria included    experience or knowledge about repair and maintenance of composite  structures, not just design or manufacturing of composite  materials/structures or accident investigations;    expertise or knowledge in advanced composite materials, including  composite materials in aircraft;  knowledge regarding FAA’s oversight of repair and maintenance of  composite materials components or aircraft; and    affiliation or association with work or research in the areas of transport  category airplanes, and not exclusively military or general aviation.
We then compiled a list of key safety concerns unique to the repair and  maintenance of composite airframe structures in transport category  airplanes through our review of the 39 documents and FAA technical  reports and our interviews with the 11 experts. To assess the extent to  which FAA actions help address these concerns, we interviewed FAA  officials, including policymakers, aviation safety inspectors, scientists, and  researchers about ongoing and planned activities. We also interviewed  industry stakeholders, including representatives from Boeing, Airbus, and  the Air Transport Association, about FAA and industry actions that help  address key safety concerns. We reviewed documentation, including  current and proposed FAA regulations, policies, and guidance; FAA  research plans; and presentations from industry working group meetings  related to the repair and maintenance of composite airframe structures or  the oversight of composite repair and maintenance. We also identified  safety concerns related to the repair and maintenance of transport  category airplanes—though not composite-specific—through our review  of our reports and prior Department of Transportation Office of Inspector  General reports.
section_title: Literature Search
paragraphs: We targeted our literature search to eight databases. We selected the  databases to contain scholarly journal articles (ProQuest, Social  SciSearch), government-conducted or government-funded research  reports (National Technical Information Service and the National  Transportation Library Digital Repository), conference proceedings  (PapersFirst), and a combination of the three above (Transportation  Research Information Services, INSPEC, PASCAL). We searched the  databases using a combination of specific keywords and subject  headings, such as “composites,” “damage,” “maintenance,” “civil  aviation,” and “aircraft industry.” Our literature search covered studies  published from 2000 onward and initially yielded results with titles and  abstracts for more than 1,000 documents. After a cursory review by our  librarian and elimination of duplicates and irrelevant documents, those  results were reduced to titles and abstracts for 659 documents.
We then identified 209 of the 659 document title and abstracts as relevant  to the scope of our review. We categorized documents as relevant if the  title and abstract indicated that the document discussed the continued  airworthiness or the repair and maintenance of airframe structures in  commercial transport category airplanes. Documents were excluded from  our review if the title and abstract indicated that the document exclusively  discussed a variety of irrelevant topics, including the use of composites in  nonairplane applications, such as orthopedics or bicycles; composites in  military applications or secondary airplane structures; airplane design and  certification; or the results of experiments for a specific theoretical model,  tool, or system.
Because many of the 209 relevant document abstracts covered similar  topics, we selected a sample of the abstracts on which to base a request  for a full document for review. To select the sample of documents, we  categorized the 209 document abstracts into 10 topics: (1) behavior  prediction, (2) damage characterization, (3) environmental effects,   (4) maintenance, (5) nondestructive inspection/evaluation, (6) repair  design, (7) repair technique or process, (8) structural health monitoring or  damage detection, (9) training, and (10) other. We then selected up to 5  documents from each of the first 9 topics and all of the documents from  the “other” topic based on the following criteria: documents whose  abstract directly refers to concerns related to repair, maintenance, or  continued airworthiness of composite airframe airplane structures; and  from the remaining documents in the topic, we chose the ones with the  most recent date—barring duplicative authors. Through this process, we  selected a sample of 52 document abstracts from the 209 relevant  document abstracts.
We requested copies of each of the 52 documents in our sample. Six of  the 52 documents were unavailable to us because of copyright  restrictions or the document was not in the English language.  Furthermore, upon review of the remaining 46 full documents, we found  that 13 were irrelevant to the scope of our review. Ultimately, we reviewed  33 full documents from our literature search to identify safety concerns  associated with the repair and maintenance of composite airframe  structures in transport airplanes.
In addition to these 33 documents, we reviewed 6 technical reports  published by FAA’s technical center. The FAA technical center provided  us with a list of 36 reports that contain aspects of composite structures.  We identified 8 of the reports as relevant through review of each report  abstract; 2 of the 8 relevant reports were duplicative of documents  identified through our literature search described above.
section_title: Appendix II: GAO Contact and Staff Acknowledgments
subsections: section_title: GAO Contact
section_title: Staff Acknowledgments
paragraphs: In addition to the contact named above, Paul Aussendorf (Assistant  Director), Rebekah Boone, Leia Dickerson, Bert Japikse, Delwen Jones,  Stan Kostyla, Gail Marnik, Jaclyn Nelson, Josh Ormond, Madhav Panwar,  and Gretchen Snoey made key contributions to this report.