Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and BD-500-1A11 Series Airplanes; Alternate Fuel Tank Structural Lightning Protection Requirements, 11859-11863 [2015-05047]

Download as PDF Federal Register / Vol. 80, No. 43 / Thursday, March 5, 2015 / Rules and Regulations * * * * * [FR Doc. 2015–05061 Filed 3–4–15; 08:45 am] BILLING CODE 6450–01–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 25 [Docket No. FAA–2014–0383; Special Conditions No. 25–578–SC] Special Conditions: Bombardier Aerospace, Models BD–500–1A10 and BD–500–1A11 Series Airplanes; Alternate Fuel Tank Structural Lightning Protection Requirements Federal Aviation Administration (FAA), DOT. ACTION: Final special conditions. AGENCY: These special conditions are issued for the Bombardier Aerospace Models BD–500–1A10 and BD–500– 1A11 series airplanes. These airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. This design feature is a nitrogen generation system (NGS) for all fuel tanks that actively reduces flammability exposure within the fuel tanks significantly below that required by the fuel tank flammability regulations. Among other benefits, the NGS significantly reduces the potential for fuel vapor ignition caused by lightning strikes. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards. DATES: This action is effective on Bombardier Aerospace on April 6, 2015. FOR FURTHER INFORMATION CONTACT: Margaret Langsted, FAA, Propulsion and Mechanical Systems Branch, ANM– 112, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98057–3356; telephone 425–227–2677; facsimile 425–227–1149. SUPPLEMENTARY INFORMATION: mstockstill on DSK4VPTVN1PROD with RULES SUMMARY: Background On December 10, 2009, Bombardier Aerospace applied for a type certificate for their new Models BD–500–1A10 and BD–500–1A11 series airplanes (hereafter collectively referred to as ‘‘CSeries’’). The CSeries airplanes are swept-wing VerDate Sep<11>2014 17:52 Mar 04, 2015 Jkt 235001 monoplanes with a composite wing fuel tank structure and an aluminum alloy fuselage that is sized for 5-abreast seating. Passenger capacity is designated as 110 for the Model BD–500–1A10 and 125 for the Model BD–500–1A11. Maximum takeoff weight is 131,000 pounds for the Model BD–500–1A10 and 144,000 pounds for the Model BD– 500–1A11. Type Certification Basis Under the provisions of Title 14, Code of Federal Regulations (14 CFR) 21.17, Bombardier Aerospace must show that the CSeries airplanes meet the applicable provisions of part 25 as amended by Amendments 25–1 through 25–129. If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR part 25) do not contain adequate or appropriate safety standards for the CSeries airplanes because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16. Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same or similar novel or unusual design feature, the special conditions would also apply to the other model under § 21.101. In addition to the applicable airworthiness regulations and special conditions, the CSeries airplanes must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36, and the FAA must issue a finding of regulatory adequacy under § 611 of Public Law 92– 574, the ‘‘Noise Control Act of 1972.’’ The FAA issues special conditions, as defined in 14 CFR 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 21.17. Novel or Unusual Design Features The CSeries airplanes will incorporate the following novel or unusual design feature: A fuel tank nitrogen generation system (NGS) that is intended to control fuel tank flammability for all fuel tanks. This NGS is designed to provide a level of performance to all fuel tanks of the CSeries airplanes that applies the more stringent standard for warm day flammability performance applicable to normally emptied tanks within the fuselage contour from § 25.981(b) and appendix M to part 25. An NGS actively reduces flammability exposure within the fuel tanks significantly below that required by the fuel tank flammability PO 00000 Frm 00003 Fmt 4700 Sfmt 4700 11859 regulations. Among other benefits, the NGS significantly reduces the potential for fuel vapor ignition caused by lightning strikes. This high level of NGS performance for all fuel tanks is a novel or unusual design feature compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. Discussion The certification basis of the CSeries airplanes includes § 25.981, as amended by Amendment 25–125, as required by 14 CFR 26.37. This amendment includes the ignition prevention requirements in § 25.981(a), as amended by Amendment 25–102, and it includes revised flammability limits for all fuel tanks and new specific limitations on flammability for all fuel tanks as defined in § 25.981(b), as amended by Amendment 25–125. Ignition Source Prevention Section 25.981(a)(3) requires applicants to show that an ignition source in the fuel tank system could not result from any single failure, from any single failure in combination with any latent failure condition not shown to be extremely remote, or from any combination of failures not shown to be extremely improbable. This requirement was originally adopted in Amendment 25–102, and it requires the assumption that the fuel tanks are always flammable when showing that the probability of an ignition source being present is extremely remote. (Amendment 25–102 included § 25.981(c) that required minimizing fuel tank flammability, and this was defined in the preamble as being equivalent to unheated aluminum fuel tanks located in the wing.) This requirement defines three types of scenarios that must be addressed in order to show compliance with § 25.981(a)(3). The first scenario is that any single failure, regardless of the probability of occurrence of the failure, must not cause an ignition source. The second scenario is that any single failure, regardless of the probability of occurrence, in combination with any latent failure condition not shown to be at least extremely remote, must not cause an ignition source. The third scenario is that any combination of failures not shown to be extremely improbable must not cause an ignition source. Demonstration of compliance with this requirement would typically require a structured, quantitative safety analysis. Design areas that have latent failure conditions typically would be driven by these requirements to have multiple fault tolerance, or ‘‘triple redundancy.’’ This means that ignition E:\FR\FM\05MRR1.SGM 05MRR1 11860 Federal Register / Vol. 80, No. 43 / Thursday, March 5, 2015 / Rules and Regulations sources are still prevented even after two independent failures. mstockstill on DSK4VPTVN1PROD with RULES Flammability Limits Section 25.981(b) states that no fuel tank fleet average flammability exposure may exceed 3 percent of the flammability exposure evaluation time calculated using the method in part 25, appendix N, or the fleet average flammability of a fuel tank within the wing of the airplane being evaluated, whichever is greater. If the wing is not a conventional unheated aluminum wing, the analysis must be based on an assumed equivalent conventional construction unheated aluminum wing. In addition, for fuel tanks that are normally emptied during operation and that have any part of the tank located within the fuselage contour, the fleet average flammability for warm days (above 80 °F) must be limited to 3 percent as calculated using the method in part 25, appendix M. Application of Existing Regulations Inappropriate Due to Impracticality Since the issuance of § 25.981(a)(3), as amended by Amendment 25–102, the FAA has conducted certification projects in which applicants found it impractical to meet the requirements of that regulation for some areas of lightning protection for fuel tank structure. Partial exemptions were issued for these projects. These same difficulties exist for the CSeries project. The difficulty of designing multiplefault-tolerant structure, and the difficulty of detecting failures of hidden structural design features in general, makes compliance with § 25.981(a)(3) uniquely challenging and impractical for certain aspects of the electrical bonding of structural elements. Such bonding is needed to prevent occurrence of fuel tank ignition sources from lightning strikes. The effectiveness and fault tolerance of electrical bonding features for structural joints and fasteners is partially dependent on design features that cannot be effectively inspected or tested after assembly without damaging the structure, joint, or fastener. Examples of such features include a required interference fit between the shank of a fastener and the hole in which the fastener is installed, metal foil or mesh imbedded in composite material, a required clamping force provided by a fastener to pull two structural parts together, and a required faying surface bond between the flush surfaces of adjacent pieces of structural material such as in a wing skin joint or a mounting bracket installation. In addition, other features that can be VerDate Sep<11>2014 17:52 Mar 04, 2015 Jkt 235001 physically inspected or tested may be located within the fuel tanks; therefore, it is not practical to inspect for failures of those features at short intervals. Examples of such failures include separation or loosening of cap seals over fastener ends and actual structural failures of internal fasteners. This inability to practically detect manufacturing errors and failures of structural design features critical to lightning protection results in degraded conditions that occur and remain in place for a very long time, possibly for the remaining life of the airplane. Accounting for such long failure latency periods in the system safety analysis required by § 25.981(a)(3) would require multiple fault tolerance in the structural lightning protection design. As part of the design development activity for the CSeries, Bombardier has examined possible design provisions to provide multiple fault tolerance in the structural design to prevent ignition sources from occurring in the event of lightning attachment to the airplane in critical locations. Bombardier has concluded from this examination that providing multiple fault tolerance for some structural elements is not practical. Bombardier has also identified some areas of the CSeries design where it is impractical to provide even single fault tolerance in the structural design to prevent ignition sources from occurring in the event of lightning attachment after a single failure. The FAA has reviewed this examination with Bombardier in detail and has agreed that providing fault tolerance beyond that in the proposed CSeries design for these areas would be impractical. As a result of the CSeries and other certifications projects, the FAA has now determined that compliance with § 25.981(a)(3) is impractical for some areas of lightning protection for fuel tank structure, and that application of § 25.981(a)(3) to those design areas is therefore inappropriate. The FAA plans further rulemaking to revise § 25.981(a)(3). As appropriate, the FAA plans to issue special conditions or exemptions, for certification projects progressing before the revision is complete. This is discussed in FAA Memorandum ANM–112–08–002, Policy on Issuance of Special Conditions and Exemptions Related to Lightning Protection of Fuel Tank Structure, dated May 26, 2009. PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 Application of Existing Regulations Inappropriate Due to Compensating Feature That Provides Equivalent Level of Safety Section 25.981(b) sets specific standards for fuel tank flammability as discussed above under ‘‘Flammability Limits.’’ Under that regulation, the fleet average flammability exposure of all fuel tanks on the CSeries airplanes may not exceed 3 percent of the flammability exposure evaluation time calculated using the method in part 25, appendix N, or the fleet average flammability of a wing main tank within an equivalent construction conventional unheated aluminum wing fuel tank, whichever is greater. The typical fleet average fuel tank flammability of fuel tanks located in the wing ranges between 1 and 5 percent. If it is assumed that a CSeries equivalent conventional unheated aluminum wing fuel tank would not exceed a fleet average flammability time of 3 percent, the actual composite airplane wing fuel tank design would be required to comply with the 3 percent fleet average flammability standard, and therefore a means to reduce the flammability to 3 percent would be required. However, the proposed CSeries design includes NGS for all fuel tanks that will also be shown to meet the additional, more stringent warm day average flammability standard in part 25, appendix M, which is only required for normally emptied fuel tanks with some part of the tank within the fuselage contour. Fuel tanks that meet this requirement typically have average fuel tank flammability levels well below the required 3 percent. Since the proposed NGS for all fuel tanks on the CSeries provides performance that meets part 25, appendix M, the FAA has determined that the risk reduction provided by this additional performance will provide compensation for some relief from the ignition prevention requirements of § 25.981(a)(3) while still establishing a level of safety equivalent to that established in the regulations. In determining the appropriate amount of relief from the ignition prevention requirements of § 25.981(a), the FAA considered the original overall intent of Amendment 25–102, which was to ensure the prevention of catastrophic events due to fuel tank vapor explosion. These special conditions are intended to achieve that objective through a prescriptive requirement that fault tolerance (with respect to the creation of an ignition source) be provided for all structural lightning protection design features where providing such fault tolerance is E:\FR\FM\05MRR1.SGM 05MRR1 mstockstill on DSK4VPTVN1PROD with RULES Federal Register / Vol. 80, No. 43 / Thursday, March 5, 2015 / Rules and Regulations practical, and through a performancebased standard for the risk due to any single failure vulnerability that exists in the design. In addition, for any structural lightning protection design features for which Bombardier shows that providing fault tolerance is impractical, these special conditions would require Bombardier to show that a fuel tank vapor ignition event due to the summed risk of all non-fault-tolerant design features is extremely improbable. Bombardier would be required to show that this safety objective is met by the proposed design using a structured system safety assessment similar to that currently used for demonstrating compliance with §§ 25.901 and 25.1309. Given these novel or unusual design features, and the compliance challenges noted earlier in this document, the FAA has determined that application of § 25.981(a)(3) is inappropriate in that it is neither practical nor necessary to apply the ignition source prevention provisions of § 25.981(a)(3) to the specific fuel tank structural lightning protection features of the Bombardier CSeries airplanes. However, without the § 25.981(a)(3) provisions, the remaining applicable regulations in the CSeries certification basis would be inadequate to set an appropriate standard for fuel tank ignition prevention. Therefore, in accordance with provisions of § 21.16, the FAA has determined that, instead of § 25.981(a)(3), alternative fuel tank structural lightning protection requirements be applied to fuel tank lightning protection features that are integral to the airframe structure of the CSeries airplanes. These alternative requirements are intended to provide the level of safety intended by § 25.981(a)(3), based on our recognition, as discussed above, that a highly effective NGS for the fuel tanks makes it unnecessary to assume that the fuel tank is always flammable. As discussed previously, the assumption that the fuel tanks are always flammable was required when demonstrating compliance to the ignition prevention requirements of § 25.981(a)(3). One resulting difference between these special conditions and the § 25.981(a)(3) provisions they are meant to replace is the outcome being prevented—fuel vapor ignition versus an ignition source. These special conditions acknowledge that the application of fuel tank flammability performance standards will reduce fuel tank flammability to an extent that it is appropriate to consider the beneficial effects of flammability reduction when considering design areas where it is impractical to comply with § 25.981(a)(3). VerDate Sep<11>2014 17:52 Mar 04, 2015 Jkt 235001 One of the core requirements of these special conditions is a prescriptive requirement that structural lightning protection design features must be fault tolerant. (An exception wherein Bombardier can show that providing fault tolerance is impractical, and associated requirements, is discussed below.) The other core requirement is that Bombardier must show that the design, manufacturing processes, and Airworthiness Limitations section of the Instructions for Continued Airworthiness include all practical measures to prevent, and detect and correct, failures of structural lightning protection features due to manufacturing variability, aging, wear, corrosion, and likely damage. The FAA has determined that, if these core requirements are met, a fuel tank vapor ignition event due to lightning is not anticipated to occur in the life of the airplane fleet. This conclusion is based on the fact that a critical lightning strike to any given airplane is itself a remote event, and on the fact that fuel tanks must be shown to be flammable for only a relatively small portion of the fleet operational life. For any non-fault-tolerant features proposed in the design, Bombardier must show that eliminating these features or making them fault tolerant is impractical. The requirements and considerations for showing it is impractical to provide fault tolerance are described in FAA Memorandum ANM–112–08–002. This requirement is intended to minimize the number of non-fault tolerant features in the design. For areas of the design where Bombardier shows that providing fault tolerant structural lightning protection features is impractical, non-faulttolerant features will be allowed provided Bombardier can show that a fuel tank vapor ignition event due to the non-fault-tolerant features is extremely improbable when the sum of probabilities of those events due to all non-fault-tolerant features is considered. Bombardier will be required to submit a structured, quantitative assessment of fleet average risk for a fuel tank vapor ignition event due to all non-faulttolerant design features included in the design. This will require determination of the number of non-fault tolerant design features, estimates of the probability of the failure of each nonfault-tolerant design feature, and estimates of the exposure time for those failures. This analysis must include failures due to manufacturing variability, aging, wear, corrosion, and likely damage. It is acceptable to consider the probability of fuel tank flammability, PO 00000 Frm 00005 Fmt 4700 Sfmt 4700 11861 the probability of a lightning strike to the airplane, the probability of a lightning strike to specific zones of the airplane (for example, Zone 2 behind the nacelle, but not a specific location or feature), and a distribution of lightning strike amplitude in performing the assessment provided the associated assumptions are acceptable to the FAA. The analysis must account for any dependencies among these factors, if they are used. The assessment must also account for operation with inoperative features and systems, including any proposed or anticipated dispatch relief. This risk assessment requirement is intended to ensure that an acceptable level of safety is provided given the non-fault-tolerant features in the proposed design. Part 25, appendix N, as adopted in Amendment 25–125, in conjunction with these special conditions, constitutes the standard for how to determine flammability probability. In performing the safety analysis required by these special conditions, relevant § 25.981(a)(3) compliance guidance is still applicable. Appropriate credit for the conditional probability of environmental or operational conditions occurring is normally limited to those provisions involving multiple failures, and this type of credit is not normally allowed in evaluation of single failures. However, these special conditions would allow consideration of the probability of occurrence of lightning attachment and flammable conditions when assessing the probability of structural failures resulting in a fuel tank vapor ignition event. The FAA understands that lightning protection safety for airplane structure is inherently different from lightning protection for systems. We intend to apply these special conditions only to structural lightning protection features of fuel systems. We do not intend to apply the alternative standards used under these special conditions to other areas of the airplane design evaluation. Requirements Provide Equivalent Level of Safety In recognition of the unusual design feature discussed above, and the impracticality of requiring multiple fault tolerance for lightning protection of certain aspects of fuel tank structure, the FAA has determined that a level of safety that is equivalent to direct compliance with § 25.981(a)(3) will be achieved for the CSeries by applying these requirements. The FAA considers that, instead of only concentrating on fault tolerance for ignition source prevention, significantly reducing fuel tank flammability exposure in addition E:\FR\FM\05MRR1.SGM 05MRR1 11862 Federal Register / Vol. 80, No. 43 / Thursday, March 5, 2015 / Rules and Regulations to preventing ignition sources is a better approach to lightning protection for the fuel tanks. In addition, the level of average fuel tank flammability achieved by compliance with these special conditions is low enough that it is not appropriate or accurate to assume in a safety analysis that the fuel tanks may always be flammable. Section 25.981(b), as amended by Amendment 25–125, sets limits on the allowable fuel tank flammability for the CSeries airplanes. Paragraph 2(a) of these special conditions applies the more stringent standard for warm day flammability performance applicable to normally emptied tanks within the fuselage contour from § 25.981(b) and part 25, appendix M, to all of the fuel tanks of the CSeries airplanes. Because of the more stringent fuel tank flammability requirements in these special conditions, and because the flammability state of a fuel tank is independent of the various failures of structural elements that could lead to an ignition source in the event of lightning attachment, the FAA has agreed that it is appropriate in this case to allow treatment of flammability as an independent factor in the safety analysis. The positive control of flammability and the lower flammability that is required by these special conditions exceeds the minimum requirements of § 25.981(b). This offsets a reduction of the stringent standard for ignition source prevention in § 25.981(a)(3), which assumes that the fuel tank is flammable at all times. Given the stringent requirements for fuel tank flammability, the fuel vapor ignition prevention and the ignition source prevention requirements in these special conditions will prevent ‘‘. . . catastrophic failure . . . due to ignition of fuel or vapors’’ as stated in § 25.981(a). Thus, the overall level of safety achieved by these special conditions is considered equivalent to that which would be required by compliance with § 25.981(a)(3) and (b). mstockstill on DSK4VPTVN1PROD with RULES Discussion of Comments Notice of proposed special conditions No. 25–14–05 for the Bombardier CSeries airplanes was published in the Federal Register on July 25, 2014 (79 FR 43318). No comments were received, and the special conditions are adopted as proposed. Applicability As discussed above, these special conditions are applicable to the Models BD–500–1A10 and BD–500–1A11 series airplanes. Should Bombardier Aerospace apply at a later date for a change to the type certificate to include VerDate Sep<11>2014 18:48 Mar 04, 2015 Jkt 235001 another model incorporating the same novel or unusual design feature, the special conditions would apply to that model as well. Conclusion This action affects only certain novel or unusual design features on two model series of airplanes. It is not a rule of general applicability. List of Subjects in 14 CFR Part 25 Aircraft, Aviation safety, Reporting and recordkeeping requirements. The authority citation for these special conditions is as follows: Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704. The Special Conditions Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the type certification basis for Bombardier Aerospace Models BD–500–1A10 and BD–500–1A11 series airplanes. ■ Alternate Fuel Tank Structural Lightning Protection Requirements 1. Definitions Most of the terms used in these special conditions either have the common dictionary meaning or are defined in Advisory Circular 25.1309– 1A, System Design and Analysis, dated June 21, 1988. The following definitions are the only terms intended to have a specialized meaning when used in these special conditions: (a) Basic Airframe Structure. Includes design elements such as structural members, structural joint features, and fastener systems including airplane skins, ribs, spars, stringers, etc., and associated fasteners, joints, coatings, and sealant. Basic airframe structure may also include those structural elements that are expected to be removed for maintenance, such as exterior fuel tank access panels and fairing attachment features, provided maintenance errors that could compromise associated lightning protection features would be evident upon an exterior preflight inspection of the airplane and would be corrected prior to flight. (b) Permanent Systems Supporting Structure. Includes static, permanently attached structural parts (such as brackets) that are used to support system elements. It does not include any part intended to be removed, or any joint intended to be separated, to maintain or replace system elements or other parts, unless that part removal or PO 00000 Frm 00006 Fmt 4700 Sfmt 4700 joint separation is accepted by the FAA as being extremely remote. (c) Manufacturing Variability. Includes tolerances and variability allowed by the design and production specifications as well as anticipated errors or escapes from the manufacturing and inspection processes. (d) Extremely Remote. Conditions that are not anticipated to occur to each airplane during its total life, but which may occur a few times when considering the total operational life of all airplanes of one type. Extremely remote conditions are those having an average probability per flight hour on the order of 1 × 10¥7 or less, but greater than on the order of 1 × 10¥9. (e) Extremely Improbable. Conditions that are so unlikely that they are not anticipated to occur during the entire operational life of all airplanes of one type. Extremely improbable conditions are those having an average probability per flight hour of the order of 1 × 10¥9 or less. 2. Alternative Fuel Tank Structural Lightning Protection Requirements For lightning protection features that are integral to fuel tank basic airframe structure or permanent systems supporting structure, as defined in Special Condition No. 1, ‘‘Definitions,’’ for which Bombardier shows and the FAA finds compliance with § 25.981(a)(3) to be impractical, the following requirements may be applied in lieu of the requirements of § 25.981(a)(3): (a) Bombardier must show that the airplane design meets the requirements of part 25, appendix M, as amended by Amendment 25–125, for all fuel tanks installed on the airplane. (b) Bombardier must show that the design includes at least two independent, effective, and reliable lightning protection features (or sets of features) such that fault tolerance to prevent lightning-related ignition sources is provided for each area of the structural design proposed to be shown compliant with these special conditions in lieu of compliance with the requirements of § 25.981(a)(3). Fault tolerance is not required for any specific design feature if: (1) For that feature, providing fault tolerance is shown to be impractical, and (2) Fuel tank vapor ignition due to that feature and all other non-faulttolerant features, when their fuel tank vapor ignition event probabilities are summed, is shown to be extremely improbable. E:\FR\FM\05MRR1.SGM 05MRR1 Federal Register / Vol. 80, No. 43 / Thursday, March 5, 2015 / Rules and Regulations (c) Bombardier must perform an analysis to show that the design, manufacturing processes, and the airworthiness limitations section of the instructions for continued airworthiness include all practical measures to prevent, and detect and correct, failures of structural lightning protection features due to manufacturing variability, aging, wear, corrosion, and likely damage. Issued in Renton, Washington, on February 25, 2015. Jeffrey E. Duven, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 2015–05047 Filed 3–4–15; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF COMMERCE Bureau of Industry and Security 15 CFR Part 748 [Docket No. 150206120–5120–01] RIN 0694–AG50 Amendments to Existing Validated End-User Authorization in the People’s Republic of China: Samsung China Semiconductor Co. Ltd. Bureau of Industry and Security, Commerce. AGENCY: ACTION: Final rule. In this rule, the Bureau of Industry and Security (BIS) amends the Export Administration Regulations (EAR) to revise the existing authorization for Validated End User Samsung China Semiconductor Co. Ltd. (Samsung China) in the People’s Republic of China (PRC). Specifically, BIS amends Supplement No. 7 to Part 748 of the EAR to add two items to Samsung China’s eligible items that may be exported, reexported or transferred (in country) to the company’s eligible facilities (also known as ‘‘eligible destinations’’) in the PRC. SUMMARY: DATES: This rule is effective March 5, 2015. MiYong Kim, Chair, End-User Review Committee, Office of the Assistant Secretary, Export Administration, Bureau of Industry and Security, U.S. Department of Commerce, Phone: 202– 482-5991; Fax: 202–482–3911; Email: ERC@bis.doc.gov. mstockstill on DSK4VPTVN1PROD with RULES FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: VerDate Sep<11>2014 21:54 Mar 04, 2015 Jkt 235001 Background Authorization Validated End-User Validated End-Users (VEUs) are designated entities located in eligible destinations to which eligible items may be exported, reexported, or transferred (in-country) under a general authorization instead of a license. The names of the VEUs, as well as the dates they were so designated, and their respective eligible destinations and items are identified in Supplement No. 7 to Part 748 of the EAR. Under the terms described in that supplement, VEUs may obtain eligible items without an export license from BIS, in conformity with Section 748.15 of the EAR. Eligible items vary between VEUs and may include commodities, software, and technology, except those controlled for missile technology or crime control reasons on the Commerce Control List (CCL) (part 774 of the EAR). VEUs are reviewed and approved by the U.S. Government in accordance with the provisions of Section 748.15 and Supplement Nos. 8 and 9 to Part 748 of the EAR. The End-User Review Committee (ERC), composed of representatives from the Departments of State, Defense, Energy, and Commerce, and other agencies, as appropriate, is responsible for administering the VEU program. BIS amended the EAR in a final rule published on June 19, 2007 (72 FR 33646) to create Authorization VEU. Amendment to Existing VEU Authorization for Samsung China Semiconductor Co. Ltd (Samsung China) in the People’s Republic of China (PRC) Revision to the List of ‘‘Eligible Items (by ECCN)’’ for Samsung China In this final rule, BIS amends Supplement No. 7 to Part 748 to add two Export Control Classification Numbers (ECCNs), 2B006.a and 2B006.b.1.d, to the list of items that may be exported, reexported or transferred (in-country) to Samsung China’s facility in the PRC under Authorization VEU. The revised list of eligible items for Samsung China is as follows: Eligible Items (by ECCN) That May Be Exported, Reexported or Transferred (In-Country) to the Eligible Destination Identified Under Samsung China Semiconductor Co. Ltd.’s Validated End-User Authorization 1C350.c.3, 1C350.d.7, 2B006.a, 2B006.b.1.d, 2B230, 2B350.d.2, 2B350.g.3, 2B350.i.3, 3A233, 3B001.a.1, 3B001.b, 3B001.c, 3B001.e, 3B001.f, 3B001.h, 3C002, 3C004, 3D002, and PO 00000 Frm 00007 Fmt 4700 Sfmt 4700 11863 3E001 (limited to ‘‘technology’’ for items classified under 3C002 and 3C004 and ‘‘technology’’ for use consistent with the International Technology Roadmap for Semiconductors process for items classified under ECCNs 3B001 and 3B002). Export Administration Act Since August 21, 2001, the Export Administration Act of 1979, as amended, has been in lapse. However, the President, through Executive Order 13222 of August 17, 2001, 3 CFR 2001 Comp., p. 783 (2002), as amended by Executive Order 13637 of March 8, 2013, 78 FR 16129 (March 13, 2013), and as extended by the Notice of August 7, 2014, 79 FR 46959 (August 11, 2014) has continued the EAR in effect under the International Emergency Economic Powers Act (50 U.S.C. 1701 et seq.). BIS continues to carry out the provisions of the Export Administration Act, as appropriate and to the extent permitted by law, pursuant to Executive Order 13222, as amended by Executive Order 13637. Rulemaking Requirements 1. Executive Orders 13563 and 12866 direct agencies to assess all costs and benefits of available regulatory alternatives and, if regulation is necessary, to select regulatory approaches that maximize net benefits (including potential economic, environmental, public health and safety effects, distributive impacts, and equity). Executive Order 13563 emphasizes the importance of quantifying both costs and benefits, reducing costs, harmonizing rules, and promoting flexibility. This rule has been determined to be not significant for purposes of Executive Order 12866. 2. This rule involves collections previously approved by the Office of Management and Budget (OMB) under Control Number 0694–0088, ‘‘MultiPurpose Application,’’ which carries a burden hour estimate of 43.8 minutes to prepare and submit form BIS–748; and for recordkeeping, reporting and review requirements in connection with Authorization VEU, which carries an estimated burden of 30 minutes per submission. This rule is expected to result in a decrease in license applications submitted to BIS. Total burden hours associated with the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.) (PRA) and OMB Control Number 0694–0088 are not expected to increase significantly as a result of this rule. Notwithstanding any other provisions of law, no person is required to respond to, nor be subject to a penalty for failure to comply with a E:\FR\FM\05MRR1.SGM 05MRR1

Agencies

[Federal Register Volume 80, Number 43 (Thursday, March 5, 2015)]
[Rules and Regulations]
[Pages 11859-11863]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-05047]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2014-0383; Special Conditions No. 25-578-SC]


Special Conditions: Bombardier Aerospace, Models BD-500-1A10 and 
BD-500-1A11 Series Airplanes; Alternate Fuel Tank Structural Lightning 
Protection Requirements

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Bombardier 
Aerospace Models BD-500-1A10 and BD-500-1A11 series airplanes. These 
airplanes will have a novel or unusual design feature when compared to 
the state of technology envisioned in the airworthiness standards for 
transport category airplanes. This design feature is a nitrogen 
generation system (NGS) for all fuel tanks that actively reduces 
flammability exposure within the fuel tanks significantly below that 
required by the fuel tank flammability regulations. Among other 
benefits, the NGS significantly reduces the potential for fuel vapor 
ignition caused by lightning strikes. The applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
this design feature. These special conditions contain the additional 
safety standards that the Administrator considers necessary to 
establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: This action is effective on Bombardier Aerospace on April 6, 
2015.

FOR FURTHER INFORMATION CONTACT: Margaret Langsted, FAA, Propulsion and 
Mechanical Systems Branch, ANM-112, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington, 98057-3356; telephone 425-227-2677; facsimile 425-227-1149.

SUPPLEMENTARY INFORMATION:

Background

    On December 10, 2009, Bombardier Aerospace applied for a type 
certificate for their new Models BD-500-1A10 and BD-500-1A11 series 
airplanes (hereafter collectively referred to as ``CSeries''). The 
CSeries airplanes are swept-wing monoplanes with a composite wing fuel 
tank structure and an aluminum alloy fuselage that is sized for 5-
abreast seating. Passenger capacity is designated as 110 for the Model 
BD-500-1A10 and 125 for the Model BD-500-1A11. Maximum takeoff weight 
is 131,000 pounds for the Model BD-500-1A10 and 144,000 pounds for the 
Model BD-500-1A11.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Bombardier Aerospace must show that the CSeries airplanes 
meet the applicable provisions of part 25 as amended by Amendments 25-1 
through 25-129.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the CSeries airplanes because of a 
novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the CSeries airplanes must comply with the fuel vent and 
exhaust emission requirements of 14 CFR part 34 and the noise 
certification requirements of 14 CFR part 36, and the FAA must issue a 
finding of regulatory adequacy under Sec.  611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.17.

Novel or Unusual Design Features

    The CSeries airplanes will incorporate the following novel or 
unusual design feature: A fuel tank nitrogen generation system (NGS) 
that is intended to control fuel tank flammability for all fuel tanks. 
This NGS is designed to provide a level of performance to all fuel 
tanks of the CSeries airplanes that applies the more stringent standard 
for warm day flammability performance applicable to normally emptied 
tanks within the fuselage contour from Sec.  25.981(b) and appendix M 
to part 25. An NGS actively reduces flammability exposure within the 
fuel tanks significantly below that required by the fuel tank 
flammability regulations. Among other benefits, the NGS significantly 
reduces the potential for fuel vapor ignition caused by lightning 
strikes. This high level of NGS performance for all fuel tanks is a 
novel or unusual design feature compared to the state of technology 
envisioned in the airworthiness standards for transport category 
airplanes.

Discussion

    The certification basis of the CSeries airplanes includes Sec.  
25.981, as amended by Amendment 25-125, as required by 14 CFR 26.37. 
This amendment includes the ignition prevention requirements in Sec.  
25.981(a), as amended by Amendment 25-102, and it includes revised 
flammability limits for all fuel tanks and new specific limitations on 
flammability for all fuel tanks as defined in Sec.  25.981(b), as 
amended by Amendment 25-125.

Ignition Source Prevention

    Section 25.981(a)(3) requires applicants to show that an ignition 
source in the fuel tank system could not result from any single 
failure, from any single failure in combination with any latent failure 
condition not shown to be extremely remote, or from any combination of 
failures not shown to be extremely improbable. This requirement was 
originally adopted in Amendment 25-102, and it requires the assumption 
that the fuel tanks are always flammable when showing that the 
probability of an ignition source being present is extremely remote. 
(Amendment 25-102 included Sec.  25.981(c) that required minimizing 
fuel tank flammability, and this was defined in the preamble as being 
equivalent to unheated aluminum fuel tanks located in the wing.) This 
requirement defines three types of scenarios that must be addressed in 
order to show compliance with Sec.  25.981(a)(3). The first scenario is 
that any single failure, regardless of the probability of occurrence of 
the failure, must not cause an ignition source. The second scenario is 
that any single failure, regardless of the probability of occurrence, 
in combination with any latent failure condition not shown to be at 
least extremely remote, must not cause an ignition source. The third 
scenario is that any combination of failures not shown to be extremely 
improbable must not cause an ignition source. Demonstration of 
compliance with this requirement would typically require a structured, 
quantitative safety analysis. Design areas that have latent failure 
conditions typically would be driven by these requirements to have 
multiple fault tolerance, or ``triple redundancy.'' This means that 
ignition

[[Page 11860]]

sources are still prevented even after two independent failures.

Flammability Limits

    Section 25.981(b) states that no fuel tank fleet average 
flammability exposure may exceed 3 percent of the flammability exposure 
evaluation time calculated using the method in part 25, appendix N, or 
the fleet average flammability of a fuel tank within the wing of the 
airplane being evaluated, whichever is greater. If the wing is not a 
conventional unheated aluminum wing, the analysis must be based on an 
assumed equivalent conventional construction unheated aluminum wing. In 
addition, for fuel tanks that are normally emptied during operation and 
that have any part of the tank located within the fuselage contour, the 
fleet average flammability for warm days (above 80 [deg]F) must be 
limited to 3 percent as calculated using the method in part 25, 
appendix M.

Application of Existing Regulations Inappropriate Due to Impracticality

    Since the issuance of Sec.  25.981(a)(3), as amended by Amendment 
25-102, the FAA has conducted certification projects in which 
applicants found it impractical to meet the requirements of that 
regulation for some areas of lightning protection for fuel tank 
structure. Partial exemptions were issued for these projects. These 
same difficulties exist for the CSeries project.
    The difficulty of designing multiple-fault-tolerant structure, and 
the difficulty of detecting failures of hidden structural design 
features in general, makes compliance with Sec.  25.981(a)(3) uniquely 
challenging and impractical for certain aspects of the electrical 
bonding of structural elements. Such bonding is needed to prevent 
occurrence of fuel tank ignition sources from lightning strikes. The 
effectiveness and fault tolerance of electrical bonding features for 
structural joints and fasteners is partially dependent on design 
features that cannot be effectively inspected or tested after assembly 
without damaging the structure, joint, or fastener. Examples of such 
features include a required interference fit between the shank of a 
fastener and the hole in which the fastener is installed, metal foil or 
mesh imbedded in composite material, a required clamping force provided 
by a fastener to pull two structural parts together, and a required 
faying surface bond between the flush surfaces of adjacent pieces of 
structural material such as in a wing skin joint or a mounting bracket 
installation. In addition, other features that can be physically 
inspected or tested may be located within the fuel tanks; therefore, it 
is not practical to inspect for failures of those features at short 
intervals. Examples of such failures include separation or loosening of 
cap seals over fastener ends and actual structural failures of internal 
fasteners. This inability to practically detect manufacturing errors 
and failures of structural design features critical to lightning 
protection results in degraded conditions that occur and remain in 
place for a very long time, possibly for the remaining life of the 
airplane.
    Accounting for such long failure latency periods in the system 
safety analysis required by Sec.  25.981(a)(3) would require multiple 
fault tolerance in the structural lightning protection design. As part 
of the design development activity for the CSeries, Bombardier has 
examined possible design provisions to provide multiple fault tolerance 
in the structural design to prevent ignition sources from occurring in 
the event of lightning attachment to the airplane in critical 
locations. Bombardier has concluded from this examination that 
providing multiple fault tolerance for some structural elements is not 
practical. Bombardier has also identified some areas of the CSeries 
design where it is impractical to provide even single fault tolerance 
in the structural design to prevent ignition sources from occurring in 
the event of lightning attachment after a single failure. The FAA has 
reviewed this examination with Bombardier in detail and has agreed that 
providing fault tolerance beyond that in the proposed CSeries design 
for these areas would be impractical.
    As a result of the CSeries and other certifications projects, the 
FAA has now determined that compliance with Sec.  25.981(a)(3) is 
impractical for some areas of lightning protection for fuel tank 
structure, and that application of Sec.  25.981(a)(3) to those design 
areas is therefore inappropriate. The FAA plans further rulemaking to 
revise Sec.  25.981(a)(3). As appropriate, the FAA plans to issue 
special conditions or exemptions, for certification projects 
progressing before the revision is complete. This is discussed in FAA 
Memorandum ANM-112-08-002, Policy on Issuance of Special Conditions and 
Exemptions Related to Lightning Protection of Fuel Tank Structure, 
dated May 26, 2009.

Application of Existing Regulations Inappropriate Due to Compensating 
Feature That Provides Equivalent Level of Safety

    Section 25.981(b) sets specific standards for fuel tank 
flammability as discussed above under ``Flammability Limits.'' Under 
that regulation, the fleet average flammability exposure of all fuel 
tanks on the CSeries airplanes may not exceed 3 percent of the 
flammability exposure evaluation time calculated using the method in 
part 25, appendix N, or the fleet average flammability of a wing main 
tank within an equivalent construction conventional unheated aluminum 
wing fuel tank, whichever is greater. The typical fleet average fuel 
tank flammability of fuel tanks located in the wing ranges between 1 
and 5 percent. If it is assumed that a CSeries equivalent conventional 
unheated aluminum wing fuel tank would not exceed a fleet average 
flammability time of 3 percent, the actual composite airplane wing fuel 
tank design would be required to comply with the 3 percent fleet 
average flammability standard, and therefore a means to reduce the 
flammability to 3 percent would be required. However, the proposed 
CSeries design includes NGS for all fuel tanks that will also be shown 
to meet the additional, more stringent warm day average flammability 
standard in part 25, appendix M, which is only required for normally 
emptied fuel tanks with some part of the tank within the fuselage 
contour. Fuel tanks that meet this requirement typically have average 
fuel tank flammability levels well below the required 3 percent.
    Since the proposed NGS for all fuel tanks on the CSeries provides 
performance that meets part 25, appendix M, the FAA has determined that 
the risk reduction provided by this additional performance will provide 
compensation for some relief from the ignition prevention requirements 
of Sec.  25.981(a)(3) while still establishing a level of safety 
equivalent to that established in the regulations.
    In determining the appropriate amount of relief from the ignition 
prevention requirements of Sec.  25.981(a), the FAA considered the 
original overall intent of Amendment 25-102, which was to ensure the 
prevention of catastrophic events due to fuel tank vapor explosion. 
These special conditions are intended to achieve that objective through 
a prescriptive requirement that fault tolerance (with respect to the 
creation of an ignition source) be provided for all structural 
lightning protection design features where providing such fault 
tolerance is

[[Page 11861]]

practical, and through a performance-based standard for the risk due to 
any single failure vulnerability that exists in the design. In 
addition, for any structural lightning protection design features for 
which Bombardier shows that providing fault tolerance is impractical, 
these special conditions would require Bombardier to show that a fuel 
tank vapor ignition event due to the summed risk of all non-fault-
tolerant design features is extremely improbable. Bombardier would be 
required to show that this safety objective is met by the proposed 
design using a structured system safety assessment similar to that 
currently used for demonstrating compliance with Sec. Sec.  25.901 and 
25.1309.
    Given these novel or unusual design features, and the compliance 
challenges noted earlier in this document, the FAA has determined that 
application of Sec.  25.981(a)(3) is inappropriate in that it is 
neither practical nor necessary to apply the ignition source prevention 
provisions of Sec.  25.981(a)(3) to the specific fuel tank structural 
lightning protection features of the Bombardier CSeries airplanes. 
However, without the Sec.  25.981(a)(3) provisions, the remaining 
applicable regulations in the CSeries certification basis would be 
inadequate to set an appropriate standard for fuel tank ignition 
prevention. Therefore, in accordance with provisions of Sec.  21.16, 
the FAA has determined that, instead of Sec.  25.981(a)(3), alternative 
fuel tank structural lightning protection requirements be applied to 
fuel tank lightning protection features that are integral to the 
airframe structure of the CSeries airplanes. These alternative 
requirements are intended to provide the level of safety intended by 
Sec.  25.981(a)(3), based on our recognition, as discussed above, that 
a highly effective NGS for the fuel tanks makes it unnecessary to 
assume that the fuel tank is always flammable. As discussed previously, 
the assumption that the fuel tanks are always flammable was required 
when demonstrating compliance to the ignition prevention requirements 
of Sec.  25.981(a)(3).
    One resulting difference between these special conditions and the 
Sec.  25.981(a)(3) provisions they are meant to replace is the outcome 
being prevented--fuel vapor ignition versus an ignition source. These 
special conditions acknowledge that the application of fuel tank 
flammability performance standards will reduce fuel tank flammability 
to an extent that it is appropriate to consider the beneficial effects 
of flammability reduction when considering design areas where it is 
impractical to comply with Sec.  25.981(a)(3).
    One of the core requirements of these special conditions is a 
prescriptive requirement that structural lightning protection design 
features must be fault tolerant. (An exception wherein Bombardier can 
show that providing fault tolerance is impractical, and associated 
requirements, is discussed below.) The other core requirement is that 
Bombardier must show that the design, manufacturing processes, and 
Airworthiness Limitations section of the Instructions for Continued 
Airworthiness include all practical measures to prevent, and detect and 
correct, failures of structural lightning protection features due to 
manufacturing variability, aging, wear, corrosion, and likely damage. 
The FAA has determined that, if these core requirements are met, a fuel 
tank vapor ignition event due to lightning is not anticipated to occur 
in the life of the airplane fleet. This conclusion is based on the fact 
that a critical lightning strike to any given airplane is itself a 
remote event, and on the fact that fuel tanks must be shown to be 
flammable for only a relatively small portion of the fleet operational 
life.
    For any non-fault-tolerant features proposed in the design, 
Bombardier must show that eliminating these features or making them 
fault tolerant is impractical. The requirements and considerations for 
showing it is impractical to provide fault tolerance are described in 
FAA Memorandum ANM-112-08-002. This requirement is intended to minimize 
the number of non-fault tolerant features in the design.
    For areas of the design where Bombardier shows that providing fault 
tolerant structural lightning protection features is impractical, non-
fault-tolerant features will be allowed provided Bombardier can show 
that a fuel tank vapor ignition event due to the non-fault-tolerant 
features is extremely improbable when the sum of probabilities of those 
events due to all non-fault-tolerant features is considered. Bombardier 
will be required to submit a structured, quantitative assessment of 
fleet average risk for a fuel tank vapor ignition event due to all non-
fault-tolerant design features included in the design. This will 
require determination of the number of non-fault tolerant design 
features, estimates of the probability of the failure of each non-
fault-tolerant design feature, and estimates of the exposure time for 
those failures. This analysis must include failures due to 
manufacturing variability, aging, wear, corrosion, and likely damage.
    It is acceptable to consider the probability of fuel tank 
flammability, the probability of a lightning strike to the airplane, 
the probability of a lightning strike to specific zones of the airplane 
(for example, Zone 2 behind the nacelle, but not a specific location or 
feature), and a distribution of lightning strike amplitude in 
performing the assessment provided the associated assumptions are 
acceptable to the FAA. The analysis must account for any dependencies 
among these factors, if they are used. The assessment must also account 
for operation with inoperative features and systems, including any 
proposed or anticipated dispatch relief. This risk assessment 
requirement is intended to ensure that an acceptable level of safety is 
provided given the non-fault-tolerant features in the proposed design.
    Part 25, appendix N, as adopted in Amendment 25-125, in conjunction 
with these special conditions, constitutes the standard for how to 
determine flammability probability. In performing the safety analysis 
required by these special conditions, relevant Sec.  25.981(a)(3) 
compliance guidance is still applicable. Appropriate credit for the 
conditional probability of environmental or operational conditions 
occurring is normally limited to those provisions involving multiple 
failures, and this type of credit is not normally allowed in evaluation 
of single failures. However, these special conditions would allow 
consideration of the probability of occurrence of lightning attachment 
and flammable conditions when assessing the probability of structural 
failures resulting in a fuel tank vapor ignition event.
    The FAA understands that lightning protection safety for airplane 
structure is inherently different from lightning protection for 
systems. We intend to apply these special conditions only to structural 
lightning protection features of fuel systems. We do not intend to 
apply the alternative standards used under these special conditions to 
other areas of the airplane design evaluation.

Requirements Provide Equivalent Level of Safety

    In recognition of the unusual design feature discussed above, and 
the impracticality of requiring multiple fault tolerance for lightning 
protection of certain aspects of fuel tank structure, the FAA has 
determined that a level of safety that is equivalent to direct 
compliance with Sec.  25.981(a)(3) will be achieved for the CSeries by 
applying these requirements. The FAA considers that, instead of only 
concentrating on fault tolerance for ignition source prevention, 
significantly reducing fuel tank flammability exposure in addition

[[Page 11862]]

to preventing ignition sources is a better approach to lightning 
protection for the fuel tanks. In addition, the level of average fuel 
tank flammability achieved by compliance with these special conditions 
is low enough that it is not appropriate or accurate to assume in a 
safety analysis that the fuel tanks may always be flammable.
    Section 25.981(b), as amended by Amendment 25-125, sets limits on 
the allowable fuel tank flammability for the CSeries airplanes. 
Paragraph 2(a) of these special conditions applies the more stringent 
standard for warm day flammability performance applicable to normally 
emptied tanks within the fuselage contour from Sec.  25.981(b) and part 
25, appendix M, to all of the fuel tanks of the CSeries airplanes.
    Because of the more stringent fuel tank flammability requirements 
in these special conditions, and because the flammability state of a 
fuel tank is independent of the various failures of structural elements 
that could lead to an ignition source in the event of lightning 
attachment, the FAA has agreed that it is appropriate in this case to 
allow treatment of flammability as an independent factor in the safety 
analysis. The positive control of flammability and the lower 
flammability that is required by these special conditions exceeds the 
minimum requirements of Sec.  25.981(b). This offsets a reduction of 
the stringent standard for ignition source prevention in Sec.  
25.981(a)(3), which assumes that the fuel tank is flammable at all 
times.
    Given the stringent requirements for fuel tank flammability, the 
fuel vapor ignition prevention and the ignition source prevention 
requirements in these special conditions will prevent ``. . . 
catastrophic failure . . . due to ignition of fuel or vapors'' as 
stated in Sec.  25.981(a). Thus, the overall level of safety achieved 
by these special conditions is considered equivalent to that which 
would be required by compliance with Sec.  25.981(a)(3) and (b).

Discussion of Comments

    Notice of proposed special conditions No. 25-14-05 for the 
Bombardier CSeries airplanes was published in the Federal Register on 
July 25, 2014 (79 FR 43318). No comments were received, and the special 
conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Models BD-500-1A10 and BD-500-1A11 series airplanes. Should Bombardier 
Aerospace apply at a later date for a change to the type certificate to 
include another model incorporating the same novel or unusual design 
feature, the special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on two model series of airplanes. It is not a rule of general 
applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

0
Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Bombardier Aerospace Models BD-500-
1A10 and BD-500-1A11 series airplanes.

Alternate Fuel Tank Structural Lightning Protection Requirements

1. Definitions

    Most of the terms used in these special conditions either have the 
common dictionary meaning or are defined in Advisory Circular 25.1309-
1A, System Design and Analysis, dated June 21, 1988. The following 
definitions are the only terms intended to have a specialized meaning 
when used in these special conditions:
    (a) Basic Airframe Structure. Includes design elements such as 
structural members, structural joint features, and fastener systems 
including airplane skins, ribs, spars, stringers, etc., and associated 
fasteners, joints, coatings, and sealant. Basic airframe structure may 
also include those structural elements that are expected to be removed 
for maintenance, such as exterior fuel tank access panels and fairing 
attachment features, provided maintenance errors that could compromise 
associated lightning protection features would be evident upon an 
exterior preflight inspection of the airplane and would be corrected 
prior to flight.
    (b) Permanent Systems Supporting Structure. Includes static, 
permanently attached structural parts (such as brackets) that are used 
to support system elements. It does not include any part intended to be 
removed, or any joint intended to be separated, to maintain or replace 
system elements or other parts, unless that part removal or joint 
separation is accepted by the FAA as being extremely remote.
    (c) Manufacturing Variability. Includes tolerances and variability 
allowed by the design and production specifications as well as 
anticipated errors or escapes from the manufacturing and inspection 
processes.
    (d) Extremely Remote. Conditions that are not anticipated to occur 
to each airplane during its total life, but which may occur a few times 
when considering the total operational life of all airplanes of one 
type. Extremely remote conditions are those having an average 
probability per flight hour on the order of 1 x 10-7 or 
less, but greater than on the order of 1 x 10-9.
    (e) Extremely Improbable. Conditions that are so unlikely that they 
are not anticipated to occur during the entire operational life of all 
airplanes of one type. Extremely improbable conditions are those having 
an average probability per flight hour of the order of 1 x 
10-9 or less.

2. Alternative Fuel Tank Structural Lightning Protection Requirements

    For lightning protection features that are integral to fuel tank 
basic airframe structure or permanent systems supporting structure, as 
defined in Special Condition No. 1, ``Definitions,'' for which 
Bombardier shows and the FAA finds compliance with Sec.  25.981(a)(3) 
to be impractical, the following requirements may be applied in lieu of 
the requirements of Sec.  25.981(a)(3):
    (a) Bombardier must show that the airplane design meets the 
requirements of part 25, appendix M, as amended by Amendment 25-125, 
for all fuel tanks installed on the airplane.
    (b) Bombardier must show that the design includes at least two 
independent, effective, and reliable lightning protection features (or 
sets of features) such that fault tolerance to prevent lightning-
related ignition sources is provided for each area of the structural 
design proposed to be shown compliant with these special conditions in 
lieu of compliance with the requirements of Sec.  25.981(a)(3). Fault 
tolerance is not required for any specific design feature if:
    (1) For that feature, providing fault tolerance is shown to be 
impractical, and
    (2) Fuel tank vapor ignition due to that feature and all other non-
fault-tolerant features, when their fuel tank vapor ignition event 
probabilities are summed, is shown to be extremely improbable.

[[Page 11863]]

    (c) Bombardier must perform an analysis to show that the design, 
manufacturing processes, and the airworthiness limitations section of 
the instructions for continued airworthiness include all practical 
measures to prevent, and detect and correct, failures of structural 
lightning protection features due to manufacturing variability, aging, 
wear, corrosion, and likely damage.

    Issued in Renton, Washington, on February 25, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-05047 Filed 3-4-15; 8:45 am]
BILLING CODE 4910-13-P