UNITED STATES OF AMERICA DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION RENTON, WASHINGTON 98057-3356

In the matter ofthe petition of Exemption No. 16779

Bombardier Aerospace Regulatory Docket No. FAA-2016-4198 for an exemption from§ 25.981(a)(3) of Title 14, Code ofFederal Regulations

GRANT OF TIME-LIMITED EXEMPTION By letters dated February 18,2016, and April4, 2016, Mr. Glenn Baxter, C Series Airworthiness Manager, BombardierAerospace (Bombardier), 400 Cote-Vertu Road West, Dorval, Quebec, H4S 1 Y9, Canada, petitioned the Federal Aviation Administration (FAA) for a time-limited exemption from the requirements of§ 25.981(a)(3) ofTitle 14, Code ofFederal Regulations (14 CFR). This exemption, ifgranted, would allow Bombardier 3 years aftertype validation to incorporate necessary design changes to the fuel boostpump onModel BD-500-1A10 and Model BD-500-1A11 airplanes in order to fully complywith 14 CFR25.981(a)(3). The petitioner requests relieffrom the following regulations: Section 25.981(a)(3)- No ignition source may be present at each point inthe fuel tank or fuel tank system where catastrophic failure could occurdue to ignition offuel or vapors. This must be shown by demonstrating that an ignition source could not result from each single failure, from each single failure in combination with each latent failure condition not shown to be extremely remote, and from all combinations offailures not shown to be extremely improbable. The effects ofmanufacturing variability, aging, wear, corrosion, and likely damage mustbe considered.Section 25.901(c)*- For each powerplant and auxiliary power unit installation, it mustbe established that no single failure or malfunction orprobable combination offailures will jeopardize the safe operation ofthe airplane except that the failure ofstructural elements need not be considered ifthe probability ofsuch failure is extremely remote. Related section of14 CFR: Section 25.1309 states, in pertinentpart, thatrequired equipment, systems, and installations mustbe designed to ensure that they perform their intended functions under any foreseeable operating condition and that the occurrence ofany failure condition that would preventthe continued safe flight and landing ofthe airplane is extremely improbable. The petitioner supports its request with the following information: This section quotes the relevant information from the petitioner's request, with minor edits for clarity. The complete petition is available at the Department ofTransportation's Federal Docket Management System, onthe Internet at http://regulations.gov, in Docket No. FAA-2016-4198. Description ofReliefSought Bombardierrespectfully requests a time-limited exemption to 14 CFR 25.981(a)(3) as it relates to the fuel alternating current (AC) boostpump design onthe BD-500-1A10 and BD-500-1A11 (C Series CS100 and C Series CS300, respectively); in particular, where the regulation states to consider "aging, wear, corrosion, and likely damage." The exemption is requested for a 3-yearperiod after FAAtype validation. Due to the impracticality ofquick redesign to include a ground fault interrupter (GFI) or a fast-acting arc fault protection, Bombardier believes temporary relieffrom§ 25.981(a)(3) relative to the fuel boostpump is appropriate. The design change will be introduced into production. Furthermore, Bombardier understands precedent exists with the FAA for this relief, most recently with FAA ExemptionNo. 11321. Justification Bombardierhas described the details in FAA Issue PaperP-32 where the AC boost pump design is claimed to meet dual fault tolerant methodology. Full compliance with § 25.981(a)(3) will require introduction ofa GFI or a fast-acting arc fault circuit protection device. Bombardier strongly believes that the AC boostpump design as outlined in Issue Paper P-32 at Stage 3, fully demonstrates that the design is robust with

•The petitioner did notrequestrelieffrom § 25

.90I(c) which is a general powerplant installation requirement. Compliance with § 25.981(a)(3) requires an analysis ofthe fuel tank system using the same analytical methods and documentation required by§ 25

.90l(c)

. Prior to the promulgation of§ 25.981 , industry had not been consistently evaluating single failures in combination with latent failures. In orderto eliminate ambiguity, § 25

.981 (a)(3) explicitly requires that latent failures be assumed unless they are extremely remote. For that reason, this exemption provides time-limited relieffrom § 25

.90I(c) in addition to time-limited relieffrom § 25

.981 (a)(3)

. 2many redundant ignition protection features to prohibit any single failure, from each single failure in combination with each latent failure condition, and from all combinations offailures to not be a threat to fuel tank ignition. Atthis time, Bombardier is assessing and evaluatingpotential design solutions to incorporate a GFI or a fast-acting arc fault circuit protection device into the AC boostpump external electrical wiring ofthe BD-500-1A10 and BD-500-1A11 in order to fully comply to§ 25.981(a)(3). Issue ofPublic Interest Since the incorporation ofthis additional feature is in development, this prevents Bombardier from certifying the Model BD-500-1A10 and BD-500-1A11 designs within a timely and competitive schedule, putting the product at an unfair disadvantage. This will, in due course, directly impactpotential customers in the United States (US) as well as BombardierUS suppliers which are heavily involved in the development ofthese airplanes. Bombardier's current design has been certified by Transport Canadaduring the baseline certification program for the C Series CS 100 aircraft. The identified FAA concerns require significant aircraft utilization and/or aging to potentially develop into a noncompliant condition. The AC boostpump is not used continuously and therefore, the timeframe proposed for this exemption is not sufficient for the affected airplanes to accumulate the flight hours or cycles required for the components to exhibit these aging effects. Effect ofthe Exemption on Safety While issuing an exemption implies a lower standard ofsafety, Bombardierbelieves that the pump as designed is more robust and better suited to preventing ignition sources than those currently installed onthousands ofaircraft that were notrequired to meet the requirements of§ 25.981(a)(3) at Amendment 25-125. Therefore, Bombardierbelieves there will not be a negative impact onthe current level ofsafety. Furthermore, the robust design ofthe BD-500-1A10 and BD-500-1A11 fuel boost pumps, in comparisonto that ofin-service aircraft not meeting the standards of§ 25.981(a)(3) at Amendment 25-125, will result in an increase in safety. In addition, the time-limited nature ofthis exemption will ensure that the number ofairplanes delivered is negligible to the overall fleet risk. Conclusion & Request to Extend Privilege ofExemption Outside the United States Bombardierbelieves that the above arguments favor a time-limited exemption from § 25.981(3)(3) regarding fuel tank ignition for the BD-500-1A10 and BD-500-1A11 airplanes. Additionally, Bombardier believes that any risk due to a fuel tank ignition is mitigated by the multiple safety features that Bombardierhas incorporated (as defined in Issue Paper P-32). The AC boostpump failure condition onthe subject airplanes will not exceed that ofcomparable existing transport category airplanes and an exemption is in the public interest. Bombardierrequests that the privileges ofthis exemption apply outside the United States due to the transoceanic capability ofthe BD-500-1A10 and 3BD-500-1A11 airplanes and the character ofmission for many ofour operators. Federal Register publication Although the petitioner requested that action on its petition not be delayed for publication in the Federal Register, the FAA found that the petition, ifgranted, would set a precedent. Therefore, to allow an opportunity for the public to comment onthe petition, a summary ofit was published in the Federal Register on April27, 2016 (81 FR24932). No comments were received. The 

### FAA's Analysis Introduction Bombardierhas requested relieffrom the requirements of§ 25.981(a)(3) as it pertains to the AC fuel boost pump installation ofthe Model BD-500-1A10 and Model BD-500-1A11 airplanes for a period of3 years. Bombardier states thatthey need 3 years to design and certify a fuel boost pump installationthat includes GFI in orderto fully comply with the requirements of § 25.981(a)(3). Bombardier also states that they will provide service information to accommodate a retrofit ofthe US fleet ofairplanes within the 3-yeartimeframe. Bombardier contends that the fuel boostpump design is robust and complies with§ 25.981(a)(3) because of many redundant ignition protection features to prohibit single failures, single failures in combination with each latent failure condition, and all combinations offailures from becoming a threat to fuel tank ignition. They statethatthe robust design ofthe fuel boostpump in comparisonto those in service that were notrequired to comply with§ 25.981(a)(3) will result in an increase in safety and that the time-limited exemption will ensure that the number ofairplanes delivered with the non-compliant design is negligible to the overall fleet risk. Bombardiermentions that aprecedent exists in Exemption 11321, issued to Airbus, for granting temporary relieffrom§ 25.981(a)(3). The FAA does not agree that Exemption 11321 sets a precedent for the Bombardier fuel boostpumpredesign because Exemption 11321 grants reliefto a fuel boostpump design that already includes a GFI and only an estimated 5 airplanes would be delivered in a non-compliant configuration. That number ofairplanes is considerably less than the number ofairplanes Bombardierestimates they will deliver during the 3-year exemption period. However, the FAA has granted time-limited exemptions specifically for certain AC fuel boost pump installations to allow applicants time to design and install GFI. Time-limited Exemption 8761C, issued to Hawker Beechcraft Corporation on September 30, 2009, grants an extension to an existing exemption to allow the applicantto design and certify a GFI and develop service information for retrofit ofthe existing fleet ofaffected airplanes. Public Interest & Effect on Safety The petitioner must showthat the granting ofthis request for exemption is in the public interest per § 11.81(d). The FAA agrees with Bombardierthat there would be adverse impacts on US 4interests, including airplane operators and component manufacturers, as a result ofdelaying approval ofa type certificate for the BD-500-1A10 and BD-500-1A11 airplanes for 3 years while Bombardier redesigns the fuel boost pump. In their petition dated February 18,2016, Bombardierproposed to design a GFI or fast-acting arc fault circuit protection. However, Bombardier later provided additional information on April 4, 2016, indicatingthatthey will design and install a GFI to disconnect powerto the fuel boost pump in the event ofa ground fault present in the fuel boostpump orthe pump powerwire. Bombardier stated that the GFI will not contain any software or complex hardware and that inadvertent operation ofthe GFI would be an active failure, preventing fuel boostpump operation. Bombardier also proposes to include an inspection ofthe GFI at an agreed upon interval to reduce the exposure to a latently failed GFI. Bombardier explains that inadvertent activation of the GFI would be an active failure because the pump operates every flight. However, inadvertent activation ofthe GFI that prevents fuel boostpump operation does not directly affect compliance with§ 25.981(a)(3). The FAA is concerned that a latent failure ofthe GFI may result in a failure to remove powerfrom the fuel boost pump in the event ofa ground fault which may result in fuel tank ignition. Compliance with§ 25.981(a)(3) requires applicants to perform a safety analysis and account for the effects ofmanufacturing variability, aging, wear, corrosion, and likely damage ofeach component ofthe fuel tank or fuel tank system. That analysis often results in the need for reliable fast-acting circuitprotectionto prevent an undetected ground fault and resultant fuel tank ignition. Service history offuel pumps has shown that safety features (e.g., explosion-proof cavities, robust connectors, insulated wires) are particularly susceptible to the effects ofaging, wear, corrosion, and damage which has typically resulted in requiring applicants to showthat the failure ofthe GFI is extremely remote or by limiting the latency period ofa failed GFI by performing a daily check. Bombardier states that they will deliver a limited number ofairplanes within the 3-yeartime period ofthe exemption and have estimated that numberto be approximately 145 to 155 airplanes; 30 ofthose airplanes will be operating in the US. A provision ofthis exemption requires Bombardierto provide service information, including all associated instructions for continued airworthiness required by§ 25.981(d) to ensure operators incorporate the new fuel boost pump design into their existing fleet. The retrofit requirement affects an estimated 30 airplanes that will be delivered to US operators priorto the incorporation ofthe compliant fuel boostpump with GFI design into production. The airplanes delivered in the non-compliant condition will be operated for a limited time and are not anticipated to develop the failure conditions that mayresult in fuel tank ignition during that limited time period. These airplanes are expected to provide a level ofsafety equal to or betterthan much ofthe existingtransport category fleet.

5Based on the service history ofexisting fleets and the limited time in whichthe new airplanes will be allowed to operate under this exemption, the risk to safety within the US fleet is very low. Therefore, we have concluded that this time-limited exemption will not adversely affect safety. The FAA has reviewed the information provided by Bombardier and acknowledges that incorporating a GFI into the AC fuel boostpumps installed on the BD-500-1A10 and BD-500-1A11 airplanes should support compliance by preventing single failures, single failures plus latent failure conditions not shown to be extremelyremote, and all failures not shown to be extremely improbable that may result in fuel tank ignition. The FAA's decision In consideration ofthe foregoing, I find that a grant oftime-limited exemption is in the public interest. Therefore, pursuant to the authority contained in49 U.S.C. 40113 and 44701 delegated to me by the Administrator, I grant Bombardier Aerospace an exemption from 14 CFR 25.901(c) and 25.981(a)(3) as it pertains to fuel tank ignition prevention associated with the fuel boost pump on the Model BD-500-1A10 and BD-500-1A11 airplanes until July 31,2019. I grant the exemptionto the extent necessary to allow Bombardier Aerospace time to incorporate into production a GFI in the fuel system design so that it is fully and directly compliant with §§ 25.901(c) and 25.981(a)(3). This exemption is subjectto the following conditions: 1. Bombardier Aerospace will develop a comprehensive plan and schedule for compliance and present them to the FAA within 90 days after issuance ofthe BD-500-1A10 and BD-500-1A11 US type certificate. 2. BombardierAerospace will complete the fuel boost pump safety analysis, including a structured failure modes and effects analysis, and provide documentation to show compliance with§ 25.901(c) at Amendment 25-126 and§ 25.981(a)(3) at Amendment 25-125, and submitto the FAAfor approval on orbefore July 31, 2017. 3. Airplanes for which the original airworthiness certificate is issued after July 31,2019, must incorporate a GFI in the AC fuel boostpumppower supply. The GFI must include a daily test to insure the GFI is functioning properly; or alternatively, Bombardier may showthat failure ofthe GFI to remove power from the fuel boost pump in the event ofa ground fault is extremely remote. 4. On orbefore July 31,2019, Bombardiermust develop and submit for FAA approval, service information for incorporating all design changes and airworthiness limitations to meet the provisions of§ 25.901(c) at Amendment 25-126 and§ 25

.981(a)(3) at Amendment 25-125, as required by§ 25.981(d)

.

65. The airworthiness limitations section ofthe instructions for continued airworthiness must state that airplanes thatreceived their original airworthiness certificate on or before July 31,2019, cannot be operated after July 31,2021, unless all design changes and limitations developed in accordance with condition 4 above are incorporated bythe owner or operator. 6. The FAA will not issue original airworthiness certificates for BombardierModel BD-500-1A10 and BD-500-1A11 airplanes after July 31,2019, unless the newly produced airplanes conform to the modified type design, incorporating GFI, which directly complies with§§ 25.901(c) and 25.981(a)(3).

Issued in Renton, Washington, on June 9, 2016.

Michael Kaszycki AssistantManager, Transport Airplane Directorate Aircraft Certification Service

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