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

In the matter ofthe petition of 

### Exemption No. 11321

Airbus SAS Regulatory Docket No. FAA-2014-1021
for an exemption from§§ 25.901(c) and 25.981(a)(3) ofTitle 14, Code ofFederal Regulations



### TIME-LIMITED PARTIAL GRANT OF EXEMPTION
By letter dated December 8, 2014, Mr. Fran<;ois Duclos, A330/A340 ChiefAirworthiness Engineer, Airbus SAS, D2202, 1rond-point Maurice Bellonte, 31707 Blagnac Cedex, France, petitioned the Federal Aviation Administration (FAA) for a time-limited exemption from the requirements of§§ 25.901(c) and 25.981(a)(3) ofTitle 14, Code ofFederal Regulations (14 CFR). This exemption, ifgranted, would allow Airbus time to complete necessary design changes ofthe center wing tank fuel system wiring and fuel pump ground fault protection on Model A330-300 airplanes while permitting on-schedule delivery to its launch customers in the United States. 

### The petitioner requests relieffrom the following regulations: Section 25.901(c), at Amendment 25-126, requires that for each powerplant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination offailures willjeopardize the safe operation ofthe airplane except that the failure ofstructural elements need not be considered ifthe probability ofsuch failure is extremely remote. 

### Section 25.981(a)(3), at Amendment25-125, requires that no ignition source may be present at each point in the fuel tank or fuel tank system where catastrophic failure could occur due to ignition offuel or vapors. It must be demonstrated 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 allcombinations offailures not shown to be extremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely damage must be considered. Related sections of 14 CFR: Section 25.1309 states, in pertinent part, that required equipment, systems, and installations must be designed to ensure that they perform their intended functions under any foreseeable operating condition and that the occurrence ofany failure condition that would prevent the continued safe flight and landing ofthe airplane be extremely improbable. Section 26.35(d)(2)- 

### Changes to type certificates affectingfuel tankjlammability, states that applicants subject to paragraph (a)(2), or (a)(3)(i) ofthis section must comply with the requirements of 14 CFR 25.981, in effect on December 26, 2008.
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, on the Internet at http:/ /regulations.gov, in DocketNo. FAA-2014-1021. The extent ofreliefsought and the reason for seeking this relief Airbus is seeking a 12-month relieffor incorporating in production on the concerned A330-300 aircraft models a fuel system design that is fully and directly compliant with 14 CFR25.981(a)(3) and 25.901(c) requirements identified above. The design changes identified as necessary for demonstrating full compliance following reviews with the FAA will indeed not be ready for incorporation on the first aircraft delivered to the US launch customer, Delta Airlines (first aircraft delivery currently targeted for end ofMay 2015). These design changes include:

• Extensive airplane wiring installation changes in the aircraft fuselage with impact on the aircraft structure in order to segregate the center tank fuel quantity indicating system (FQIS) wiring from other airplane wiring with a physical separation distance;

• Addition ofa second ground fault interrupter (GFI) for each ofthe center tank fuel transfer pumps power supplies

. The 12-monthreliefis requested from the date offirst A330-300 delivery to Delta Airlines; i

.e., based on current delivery planning up until the end ofMay 2016. At the time ofpetitioning, it is estimated that around five aircraft would be delivered to Delta Airlines during this exemption period. There is no intention to retrofit these first five aircraft. Reasons why granting this request would be in the public interest Denial ofthis petition for exemption would imply a delay ofseveral months inthe delivery ofthe first A330-300 with fuel centertank activated to the US launch customer, DeltaAirlines. This would therefore deprive Delta and its flying customers from the benefits brought by these aircraft which will allow carrying more payloads on longer 2missions. Denial would also have negative impacts on the numerous US suppliers of Airbus (as an example, UTAS, A330/A340 fuel system supplier) due to the delivery delays. Forthese reasons, granting the request would benefit the US public as a whole. Reasons why granting the exemption would not adversely affect safety The baseline design for the A330-300 fuel center tank is the well proven design ofthe A330-200 and A340-200/300 aircraft models (which has now accumulated more than 30 million hours ofrevenue flight time) with all SFAR 88 corrective actions mandated by the FAA including the fitment ofa Ground Fault Interrupter (GFI) on the power supply of the two fuel transfer pumps. The same Flammability Reduction System (FRS) as designed for the A330-200 and A340-200/300 will also be incorporated, limiting the center tank flammability exposure to levels below 0.5%, i.e., well within the requirements of 14 CFRAppendix M25.1 at amendment 125. In addition to this already safe baseline design that will be embodied on the first aircraft delivered to DeltaAirlines, Airbus has voluntarily defined additional airplane wiring design improvements in the frame ofthe activation ofthe A330-300 fuel center tank. These improvements, listed below, will also be incorporated in the first aircraft delivered to DeltaAirlines:

• Addition ofclamps on electrical bundles in zone adjacent to the center tank in order to minimize the risk ofchafing in case ofan attachment point failure.

• Additional metallic overbraiding on the center tank FQIS wiring in orderto limit the level ofinduced currents in case oflightning strike.

• Additional electrical and mechanical protection sleeve on the center tank FQIS wiring in order to prevent the risk ofinduced current from short circuits due to the co-routing with other low energy non-intrinsically safe (28VDC) airplane wiring. Forthe FQIS wiring installation, those additional changes will already raise the level of robustness ofthe A330-300 modified areas against the risk ofcreating a fuel tank ignition
over and above the already currently flying safe baseline. Compliance to the higher certification standard of 14 CFR25.981(a)(3), Amendment 25-125, and to 14 CFR 25.901(c), Amendment 25-126, will be demonstrated exceptfor the 'no single failure in combination withprobable (i.e., with a probability greater than extremely remote) latent failure condition provision due to the following extremely improbable specific residual risk: a foreign object or undue contact with an adjacent structure damaging the FQIS wiring protection sleeve and causing a short circuit between FQIS wiring and low energy non-intrinsically safe wiring outside the fuel tank in combination with a latent in-tank short circuit due to the filament heating phenomenon, during a period where the fuel tank is flammable (i.e., thanks to the FRS less than 0

.5% ofthe Flammability Exposure Evaluation Time)

. Based on these considerations, it can be determined that the design changes necessary to reach full compliance will be embodied on a design configuration which is considered as providing already an adequate level ofsafety. Therefore, granting the exemption to allow

3additional time to incorporate them and to deliver the first aircraft without later retrofit action will not adversely affect safety

. As far as the fuel transfer pumps GFI are concerned, the basic design incorporated on the first A330-300 with fuel center tank activated has already been demonstrated to be compliant with 14 CFR 25.981(a)(3), at Amendment 25-102, and with 14 CFR25.901(c) (refer to ELOS memo TD0764ID-T-P-1). Section 14 CFR 25.981(a)(3), at Amendment 25-125, is unchanged compared to Amendment 25-102. However, compliance has been found by the FAA using an alternate (ELOS) methodology and the FAA notified Airbus that direct compliance to 14 CFR 25

.981(a)(3), at Amendment 25-125 and 14 CFR 901(c) would be required for the A330-300 fuel center tank activation project. Additional design changes (addition ofa second GFI on each transfer pump power supply) are necessary to achieve this direct compliance

. Those changes will be embodied on a design configuration which has been already demonstrated as safe, based on in-service experience. Granting this exemption to allow additional time to incorporate them and to deliver the first aircraft without later retrofit action will therefore not adversely affect safety.
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 on the petition, we published a summary ofit in the Federal Register on January 20, 2015 (80 FR 2774). We received comments from the National Air Traffic Controllers Association (NATCA) and The Boeing Company. Neither commenter objected to the issuance ofa time-limited partial exemption in this case
. Below is a summary ofthe comments. NA TCA does not object to a 12-month time-limited exemptionthat would allow delivery of approximately five non-compliant airplanes to a U.S. operator while Airbus develops and implements design changes necessary to bring the center wing tank installation into compliance with 14 CFR 25

.901(c) and 25.981(a)(3)

. However,NATCA does not believe the petitioner's request complies with 14 CFR 11.81 , specifically how the exemption "would not adversely affect safety, or howthe exemption would provide a level ofsafety at least equal to that provided by the rule from which you seek the exemption." NATCA recommends that the FAA grant a timelimited exemption that includes a requirement for operators to modify their existing airplanes to bring those installations into compliance with 14 CFR 25

.901(c) and 25.981(a)(3). NATCA notes two other time-limited exemptions involving 14 CFR 25

.981(a)(3) that required modifying airplanes produced under the exemption to bring them into full compliance

. The Boeing Company has no objections to the Airbus petition as proposed

. However, they commented on a draft advisory circular and questioned whether design changes are even necessary for Airbus to comply with 14 CFR 25

.901 (c) and 25.981(a)(3)

.

4The FAA's analysis The petitioner must showthat granting this request is in the public interest,per 14 CFR 11.81(d), and will not adversely affect safety or that a level ofsafety will be provided that is equal to that provided by the rules from which the exemption is sought, per 14 CFR 11.81(e). The FAA agrees with the petitioner that adverse impacts on U.S

. interests, including airplane operators-and component manufacturers, as a result ofdelaying approval ofthis amended type design for approximately one-year is not warranted. We consider that this granting would not materially impact the level ofsafety given the limited number ofnoncompliant airplanes the petitioner expects to deliver and the compensating design features the petitioner will introduce for those airplanes. The petitioner estimates that approximately five airplanes will be delivered before they are able to incorporate a fully compliant design into production. They also state that they have no plans to make service information available that would support bringing those five airplanes into full compliance. The center wing fuel tank installation ofthe Model A330-300 series airplane is based onthe current center wing fuel tank design ofthe Model A330-200 and Model A340-200/300 series airplanes. However, the petitioner has identified additional design features ofthe FQIS wiring installation intended to increase the level ofsafety over the existing design by providing increased protection from wiring damage and induced energy from lightning strikes

. The FAA considers that the current center wing fuel tank installation on Model A330-200 and Model A340-200/300 series airplanes, which includes flammability reduction means meeting 14 CFR 25.981(b) at Amendment 25-125, provides an adequate level ofsafety. The FAA also considers the addition ofthe limited number ofairplanes into service with similar center wing fuel tank installations that also incorporate additional design features to protect FQIS wiring would not adversely affect safety. While the center wing fuel tank installation on these five A330-300 series airplanes will not be fully compliant with§§ 25.901(c) and 25.981(a)(3), we consider that the additional design features would in fact provide a greater level ofsafety than the current design in use on Model A330-200 and Model A340-200/300 series airplanes. Forthese reasons, we do not consider the retrofit ofthese airplanes with fully compliant designs necessary
. The petitioner's installation ofa center wing fuel tank on the Model A330-300 series airplane meets the applicability requirements in 14 CFR 26

.35(a)(3)(i), and therefore, they must meet 14 CFR 26.35(d)(2) requiring compliance with the requirements of 14 CFR 25.981 in effect on December 26, 2008 (Amendment 25-125)

. While not specifically included in the petition for exemption, we find that we should include 14 CFR 26

.35(d)(2) in this granting since it requires compliance with 14 CFR 25.981 at Amendment 25-125

. One commenter,NATCA, stated that they do not believe the petition meets the conditions for granting an exemptionper 14 CFR 11.81. We do not agree. We consider that the petition provided all ofthe necessary public interest and safety information and therefore meets the conditions required for granting an exemption. NATCArequested the FAA grant only a time-limited exemption that includes a requirement for operators to modify their existing airplanes to bring those installations into full compliance with 514 CFR 25.901(c) and 25.981(a)(3) after the time-limited exemption expires. We infer that the commenter is proposing to only address the limited number ofModel A330-300 series airplanes delivered with a center wing fuel tank installation that is not fully compliant with 14 CFR 25.901(c) and 25.981(a)(3) and not a request for operators to bring all Model A330-300 series airplanes into full compliance. We do not agree and as previously discussed, we consider the design proposed by Airbus for the limited number ofairplanes that would not be fully compliant provides a greater level ofsafety than that ofthe existing Model A330-200 series airplanes with a similar center wing fuel tank installation and thus would not adversely affect safety. NA TCA referred to two exemptions that required airplanes to be modified to bring them into full compliance with 14 CFR25.981(a)(3). These exemptions granted much broader temporary relief from all aspects of 14 CFR25.981(a)(3) involving all fuel tank systems onthose airplanes. Due to the scope ofthe exemptions, we determined it necessary to bring the airplanes producedunder the exemptions into compliance. We have granted other exemptions, similar in scope to this petition, where we did not require full-compliance modifications to in-service airplanes (e.g., ExemptionNos. 10767 and 1 0905). Another commenter, Boeing, commented on FAA guidance regarding fuel pump protective features and did notpropose any specific changes or propose we deny the petitioner's request. We infer the comments are in response to the proposed changes to Advisory Circular (AC) 25.981-1C that is currently open for comment. The FAA recommends Boeing referto the FAA's Aircraft Certification Service website* for draft ACs that are open for comment for instructions and submit their specific comments onthe draft AC for ourconsideration. Boeing commented on the need for Airbus to redesign the Model A330-300 series airplane's fuel pump protection/GFI design and their position that it is unwarranted based on service experience and GFI failure conditions for current Boeing designs. We inferthat Boeingrequests the FAA deny the petitioner's request because they believe a redesign is unnecessary. We do not agree. Airbus requested this time-limited exemption because they are unable to demonstrate that their existing design directly complies with 14 CFR 25.901(c) at Amendment 25-126 and 14 CFR 25.981(a)(3) at Amendment 25-125. The GFI design features are required for a full compliance demonstration.
The 

### FAA's decision In consideration ofthe foregoing, I find that a time-limited partial grant ofexemption is in the public interest. Therefore, pursuantto the authority contained in 49 U.S.C. §§ 40113 and 44701 delegated to me by the Administrator, I grant Airbus a partial exemption from 14 CFR 25.901(c) at Amendment 25-126, 14 CFR 25.981(a)(3) at Amendment 25-125 and 14 CFR26.35(d)(2) as they pertainto fuel tank ignition prevention associated with the FQIS wiring and fuel pump GFI introduced by the installation ofthe center wing fuel tank on the Model A330-300 series airplanes until May 31 , 2016. We grant the exemptionto the extent necessary to allow Airbus time to incorporate a fuel system design that is fully and directly compliant into production on the Model A330-300 series airplanes equipped with a center wing fuel tank while maintaining their current delivery schedule.

• http://www.faa

.gov/aircraft/draft docs/ac/ 6This exemption is subject to the following conditions: 1. No later than May 31 , 2016, Airbus must;

a. Obtain FAA approval ofa type design eliminating all noncompliant features as they pertain to fuel tank ignition prevention ofthe center wing fuel tank installation, and b. Showthat all new production Model A330-300 series airplanes equipped with a center wing fuel tank incorporate the FAA-approved amended type design that is fully and directly compliant with 14 CFR 25.901(c) at Amendment 25-126 and 14 CFR 25

.981(a)(3) at Amendment 25-125.
2. Model A330-300 airplanes with center wing fuel tanks installed that are granted a certificate ofairworthiness prior to May 31 , 2016, are not required to incorporate the design changes developed for complying with condition 1. However, the following design features identified by the petitioner in their petition shall be mandatory for those airplanes:

a. Addition ofclamps on electrical bundles in zones adjacentto the center tank in order to minimize the risk ofchafing in case ofan attachment point failure. b. Additional metallic over-braiding on the center tank FQIS wiring in order to limit the level ofinduced currents in case oflightning strike.

c. Additional electrical and mechanical protection sleeve onthe centertank FQIS wiring in order to prevent induced current from short circuits due to co-routing with other low energy, non-intrinsically safe (28VDC) airplane wiring

.



# ~P- APR 14 2015

Michael Kaszycki Acting Manager, Transport Airplane Directorate Aircraft Certification Service

7