UNITED STATES OF AMERICA 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

RENTON, WASHINGTON 98057-3356 

In the matter of the 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 of Federal 

Regulations 

TIME-LIMITED PARTIAL GRANT OF EXEMPTION 

By letter dated December 8, 2014, Mr. Fran<;ois Duclos, A330/A340 Chief Airworthiness 

Engineer, Airbus SAS, D2202, 1 rond-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) of Title 14, Code of Federal Regulations 

(14 CFR). This exemption, if granted, would allow Airbus time to complete necessary design 

changes of the 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 relief from 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 of failures will jeopardize the safe operation of the 

airplane except that the failure of structural elements need not be considered if the 

probability of such failure is extremely remote. 

Section 25.981(a)(3), at Amendment 25-125, 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 of fuel 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 all 
combinations of failures 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 of any failure condition that 

would prevent the continued safe flight and landing of the 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) of this 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 of Transportation's Federal Docket 

Management System, on the Internet at http://regulations.gov, in Docket No. FAA-2014-1021. 

The extent of relief sought and the reason for seeking this relief 

Airbus is seeking a 12-month relief for incorporating in production on the concerned 

A330-300 aircraft models a fuel system design that is fully and directly compliant with 

14 CFR 25.981(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 of May 

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 of a second ground fault interrupter (GFI) for each of the center tank fuel 

transfer pumps power supplies. 

The 12-month relief is requested from the date of first A330-300 delivery to Delta 

Airlines; i.e., based on current delivery planning up until the end ofMay 2016. At the 

time of petitioning, 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 of this petition for exemption would imply a delay of several months in the 

delivery of the first A330-300 with fuel center tank activated to the US launch customer, 

Delta Airlines. This would therefore deprive Delta and its flying customers from the 

benefits brought by these aircraft which will allow carrying more payloads on longer 

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missions. 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. For these 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 of the 

A330-200 and A340-200/300 aircraft models (which has now accumulated more than 30 

million hours of revenue flight time) with all SF AR 88 corrective actions mandated by 

the FAA including the fitment of a 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 CFR Appendix M25.1 at amendment 125. 

In addition to this already safe baseline design that will be embodied on the first aircraft 

delivered to Delta Airlines, Airbus has voluntarily defined additional airplane wiring 

design improvements in the frame of the activation of the A330-300 fuel center tank. 

These improvements, listed below, will also be incorporated in the first aircraft delivered 

to Delta Airlines: 

• Addition of clamps on electrical bundles in zone adjacent to the center tank in 

order to minimize the risk of chafing in case of an attachment point failure. 

• Additional metallic overbraiding on the center tank FQIS wiring in order to limit 

the level of induced currents in case of lightning strike. 

• Additional electrical and mechanical protection sleeve on the center tank FQIS 

wiring in order to prevent the risk of induced current from short circuits due to the 

co-routing with other low energy non-intrinsically safe (28VDC) airplane wiring. 

For the FQIS wiring installation, those additional changes will already raise the level of 

robustness of the A330-300 modified areas against the risk of creating a fuel tank ignition 

over and above the already currently flying safe baseline. Compliance to the higher 

certification standard of 14 CFR 25.981(a)(3), Amendment 25-125, and to 14 CFR 

25.901(c), Amendment 25-126, will be demonstrated except for the 'no single failure in 

combination with probable (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% of the 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 of safety. Therefore, granting the exemption to allow 

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additional 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 CFR 25.901(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 of a 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, if granted, would set a precedent. Therefore, 

to allow an opportunity for the public to comment on the petition, we published a summary of it 

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 of a time-limited partial exemption in this case. Below is a 

summary ofthe comments. 

NA TCA does not object to a 12-month time-limited exemption that 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 how the exemption would provide a level of safety 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). 

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The FAA's analysis 

The petitioner must show that granting this request is in the public interest, per 14 CFR 11.81 (d), 

and will not adversely affect safety or that a level of safety 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 of delaying approval of this amended type 

design for approximately one-year is not warranted. We consider that this granting would not 

materially impact the level of safety given the limited number of noncompliant 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 of the Model A330-300 series airplane is based on the 

current center wing fuel tank design of the 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 of safety 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 of safety. The FAA also 

considers the addition of the limited number of airplanes 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 of safety than the 

current design in use on Model A330-200 and Model A340-200/300 series airplanes. For these 

reasons, we do not consider the retrofit ofthese airplanes with fully compliant designs necessary. 

The petitioner's installation of a 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 exemption per 14 CFR 11.81. We do not agree. We consider that the petition 

provided all of the necessary public interest and safety information and therefore meets the 

conditions required for granting an exemption. 

NATCA requested 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 

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14 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 of Model 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 of airplanes that would not be fully compliant 

provides a greater level of safety than that of the 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 CFR 25.981(a)(3). These exemptions granted much broader temporary relief 

from all aspects of 14 CFR 25.981(a)(3) involving all fuel tank systems on those airplanes. Due 

to the scope of the exemptions, we determined it necessary to bring the airplanes produced under 

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., 

Exemption Nos. 10767 and 1 0905). 

Another commenter, Boeing, commented on FAA guidance regarding fuel pump protective 

features and did not propose 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) 

25.981-1 C that is currently open for comment. The FAA recommends Boeing refer to the FAA's 

Aircraft Certification Service website* for draft ACs that are open for comment for instructions 

and submit their specific comments on the draft AC for our consideration. 

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 infer that Boeing requests 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 of the foregoing, I find that a time-limited partial grant of exemption is in the 

public interest. Therefore, pursuant to 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 25.90 1 (c) 

at Amendment 25-126, 14 CFR 25.981(a)(3) at Amendment 25-125 and 14 CFR 26.35(d)(2) as 

they pertain to fuel tank ignition prevention associated with the FQIS wiring and fuel pump GFI 

introduced by the installation of the center wing fuel tank on the Model A330-300 series 

airplanes until May 31 , 2016. We grant the exemption to 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/ 

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This exemption is subject to the following conditions: 

1. No later than May 31 , 2016, Airbus must; 

a. Obtain FAA approval of a type design eliminating all noncompliant features as 

they pertain to fuel tank ignition prevention of the center wing fuel tank 

installation, and 

b. Show that 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 of airworthiness 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 of clamps on electrical bundles in zones adjacent to the center tank in 

order to minimize the risk of chafing in case of an attachment point failure. 

b. Additional metallic over-braiding on the center tank FQIS wiring in order to limit 

the level of induced currents in case of lightning strike. 

c. Additional electrical and mechanical protection sleeve on the center tank 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 

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