Exemption No. 10767A

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

RENTON, WASHINGTON 98057-3356

In the matter of the petition of

The Boeing Company

for an exemption from §§ 25.901(c) and 

25.981(a)(3) of Title 14, Code of Federal 

Regulations

Regulatory Docket No. FAA-2012-1132

TIME-LIMITED PARTIAL GRANT OF EXEMPTION

By letter dated August 18, 2014, Douglas M. Lane, Director, Regulatory Administration, The 

Boeing Company, P.O. Box 3707, Seattle, WA 98124, petitioned the Federal Aviation 

Administration (FAA) for an amendment to Exemption No. 10767, issued on May 17, 2013. 

That exemption granted Boeing time-limited, partial relief from the requirements of §§ 25.901(c) 

and 25.981(a)(3) of Title 14, Code of Federal Regulations (14 CFR) for planned changes to the 

fuel quantity indication system (FQIS) for the fuel quantity processor unit (FQPU) parts 

obsolescence modification on the Boeing Models 767-200/-300/-300F/-400ER. The petitioner 

requests an amendment to Exemption No. 10767 to extend it until 2019 to provide coverage 

through the end of the currently committed 767-300 and -300F production activity.

The petitioner requests relief from the following regulation(s):

Section 25.901(c) – Installation.

(c) 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) – Fuel tank ignition prevention.

(a) 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. This must be 

shown by: 

(3) 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 of failures not shown to be extremely 
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improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely 

damage must be considered.

Related section of 14 CFR:

Section 25.1309 – Equipment, systems, and installations, states that required equipment, 

systems, and installations 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.

The petitioner supports the request with the following information:

This section quotes the relevant information from the petitioner’s request. The complete petition 

is available at the Department of Transportation’s Federal Docket Management System (FDMS) 

on the Internet at http://www.regulations.gov in Docket No. FAA-2012-1132.

Description of Issue:

Background:

The 767 Fuel Quantity Processer Unit (FQPU) uses digital ARINC 429 busses to 

receive/transmit data to the flight deck, EICAS and refueling panels through two 

redundant Input/Output Channel (IOC) circuit cards. The current production IOC card 

utilizes many integrated electronic microchips to transmit and receive the ARINC 429 

data. One of the microchips, which is involved with communication to the flight deck and 

refueling panel, has been out of production for several years, and the supply has now 

become exhausted.

In February 2012 the FQPU supplier informed Boeing that the supply of this particular 

ARINC 429 chip used on the two IOC cards and also on the [built-in test equipment] 

BITE card will run out in late 2012 and that there were no sources for procurement of the 

current chip. The supplier initiated a contract with another chip manufacturer to develop a 

replacement chip to the unchanged requirements of the original chip as defined by the 

supplier’s Specification Control Document. The new chip, by requirement, is an identical 

form-fit-function replacement to the current production chip. In August 2012, Boeing and 

the supplier reviewed the existing stores of parts and determined the existing supply 

would support production through January 2013 with a possible extension into March 

2013.

In the previous exemption application for this subject, The Boeing Company 

communicated that if showing full compliance to 25.901(c) Amendment Level 25-126 

and 25.981(a)(3) Amendment Level 25-125 for the FQIS at the system level was required 

due to replacing this obsolescent chip with an identical form-fit-function chip, then a 

significant number of changes would be required to the FQIS intrinsically safe side 

wiring. The previous exemption was granted as a time-limited exemption (reference 

exemption number 10767), expiring in 2016, after which full compliance of the FQIS 

would be required. Since the issuance of the time limited exemption, The Boeing 
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Company has been working on a FQIS that would meet the requirements and has 

quantified the design change required and the cost of the new design. Based on these 

findings the Boeing Company is petitioning for a new time limited exemption to address 

the remaining production of the 767-300 and -300F.

Discussion:

This new petition for a time limited exemption is being made since full compliance to 

these rules for the 767 would require extensive system design changes which do not 

substantially improve the safety of the current airplane design, are economically 

prohibitive given the remaining production of the 767-300 and -300F and are not in the 

public’s interest. In conjunction with this petition The Boeing Company is proposing to 

incorporate significant improvements to newly produced 767 airplanes that will increase 

the level of safety by addressing both ignition sources and exposure time.

Boeing proposes that all new production airplanes incorporate design changes similar to 

the center fuel tank wire separation being developed by SB 767-28-XXXX which will be 

required by AD for all 767 freighters that do not have NGS. These wire separation 

changes would be implemented on all new production airplanes one year after the 

exemption is granted. Boeing will further address ignition sources by requiring a three 

tank, 750 hour BITE check, similar to instructions for the center wing tank provided in a 

SB 767-28-0118 for freighters without NGS, and being required by AD. The proposed 

BITE instructions would apply to all tanks.

All newly produced 767 airplanes, since line number 993 in July 2010, address 

flammability exposure time with the incorporation of a center tank fuel tank flammability 

reduction system, the Nitrogen Generation System (NGS). This addresses exposure time 

as required for all 767 in-service passenger airplanes and adds flammability reduction 

systems for all freighter airplanes since line number 993.

In the previously granted time limited exemption, the FAA stated that current fuel tank 

safety airworthiness standards rely upon a balanced approach of precluding ignition 

sources that could form in the fuel tanks and limiting fuel tank flammability exposure 

time. The aforementioned fuel tank wire separation, BITE check and flammability 

reduction system will address both exposure time and ignition sources for all newly 

produced 767 airplanes, both passenger and freighter.

This time limited exemption is being sought for the no single plus latent (greater than 

extremely remote) as is stated in §25.981(a)(3) and interpreted by the FAA for

§25.901(c). Exemption is also being sought for the non-environmental aspects of

§25.901(c) provided by FAA interpretation, and the explicit §25.981(a)(3) requirements 

of manufacturing variability, aging, wear, corrosion, and likely damage, as these 

considerations are already covered by factory manufacturing processes, and airline 

maintenance of the type design of airplane. Exemption is requested to apply through the 

end of 2019 to provide coverage through the end of the currently committed 767-300 and

-300F production activity and potential incremental sales. The 767-2C, which will be 

produced beyond 2019, will be fully compliant to these requirements.
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Statement of Public Interest:

In support of this petition, Boeing is proposing to address both ignition sources and 

exposure time in the center tank (NGS on all newly produced airplanes). In-service 

airplanes are currently required to address either exposure time (passenger airplanes) or 

ignition sources (freighter airplanes) but not both. This approach addresses both aspects, 

incorporating improvements to address both ignition sources and exposure time.

All new production airplanes will incorporate design changes similar to the center fuel 

tank wire separation being developed by SB 767-28-XXXX which will be required by 

AD for all 767 freighters that do not have NGS. These wire separation changes will be

implemented on all new production airplanes one year after the exemption is granted and 

will be made with the guidance of 28-AWL-09. In addition, Boeing is proposing a three 

tank, 750 hour BITE check, similar to instructions for the center tank provided in SB767-

28-0118 for freighters without NGS, and being required by AD. These changes will 

address ignition sources on all newly produced 767 airplanes.

All newly produced 767 airplanes, since line number 993 in July 2010, address 

flammability exposure time with the incorporation of a center tank fuel tank flammability 

reduction system, the Nitrogen Generation System (NGS). This addresses exposure time 

as required for all 767 in-service passenger airplanes and adds flammability reduction 

systems for all freighter airplanes since line number 993.

By addressing both exposure time and ignition sources, newly produced 767 airplanes 

will use a balanced approach and achieve a higher level of safety than any in-service 767 

airplane. Design changes that would be required to be fully compliant would not provide 

a significant benefit or increased level of safety for new production airplanes that 

incorporate the proposed wire separation, BITE check, and have the Nitrogen Generation 

System (NGS) installed. Additionally, the costs associated with these changes would not 

be commensurate with the increased level of safety and would be economically 

prohibitive given the relatively small number of additional production aircraft that would 

be burdened with these costs. These changes would include the following:

• New system architecture and extensive airplane wiring changes to ensure adequate 

wire separation throughout the fuel quantity indication system.

• In-tank component changes (new brackets, potential need for shorter probes, 

revised in-tank wire harness and retention means).

• Software changes related to Fuel Tank Gauging Function and Safety function if 

shorter probes are required.

Release of new Boeing design architecture requirements, supplier development and 

qualification of new software and hardware to be fully compliant would negatively affect 

offerability of the 767-300 and 300F airplanes. These design changes would also affect 

only one customer and result in an undesirable configuration mix for that customer, 

driving maintenance complexity and increased operational costs.
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Finally, the associated design proposal in support of this petition for exemption will 

implement center tank FQIS limited wire separation and a three tank FQIS BITE check 

earlier than other alternatives, approximately one year after grant of the petition. This will 

provide important enhancements to airplane safety earlier, and on more production 

airplanes. Please note, relief is not being sought for the 767-2C, which will be fully 

compliant with a new FQIS, and is anticipated to be the only minor model produced for 

the next several decades.

Granting this time limited exemption is in the public interest for the aforementioned 

reasons and will:

1. Promote continued production of the 767 airplane after May 17, 2016, currently 

forecasted to end in 2019. All production airplanes will address fuel tank safety 

with incorporation of wire separation, scheduled health checks, and a fuel tank 

inerting system (NGS). A grant of exemption will also provide significant 

economic benefit to the public in the form of continued 767 production and support 

efficient, safe operation by our customers by providing a consistent fleet 

configuration.

2. The proposal for this exemption request of implementing the center tank FQIS 

limited wire separation and three tank FQIS BITE check can be accomplished on 

an earlier schedule, (proposed to be one year after the exemption is granted) 

enhancing safety earlier on more airplanes.

Statement of No Adverse Effect on Safety:

The replacement of the existing ARINC 429 chip with the new replacement chip does not 

adversely affect the safety of the current system. There is no threat to fuel tank ignition 

from the IOCs within the FQPU because there is no electrical conductor connection 

between the boards with the obsolete chip and the fuel tank. Hence, the change has no 

relation to fuel tank ignition prevention, does not impact line replaceable unit (LRU) or 

system level failure modes, effects, or probabilities relative to fuel tank ignition and 

therefore has no affect [sic] on the safety of the system and has no impact to airplane 

safety.

The 767 FQIS was found to be compliant to §25.901(c) during airplane type certification 

for the FQIS change in 1992 and since then Boeing has completed the SFAR88 safety 

assessment and has increased the airplane fuel system safety with installation of a hot 

short protector for the densitometer and with installation of a NGS for the center fuel 

tanks. The proposed change to address the previous time limited exemption has no impact 

on any of the SFAR88 related assessments.

Even prior to the implementation of NGS which further reduces any risk, the Boeing 

assessment was that the risks for the 767 FQIS installation were extremely improbable, 

which is the typical industry and CFR §25.1309 standard for an acceptable safety for 

systems.
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The Boeing approach to incorporate design changes to add center fuel tank fuel wire 

separation, a three tank 750 hour BITE check, and installation of NGS on all newly 

produced 767 airplanes will provide for an improved safety margin over the existing, 

approved in-service fleet. These changes are also proposed to be done one year after 

grant of exemption, thereby incorporating changes to more airplanes than possible under 

the existing time limited exemption.

Request to Waive Publication and Comment:

Given the time-sensitive nature of this request for exemption, Boeing respectfully 

requests that the FAA waive the “publication and comment” step in the process for 

making a final decision on this exemption. In addition to the timeliness concern, it is the 

Boeing position that the safety-associated aspects related to this system have been fully 

vetted in the public forum as part of the SFAR88 project and the previous time-limited 

partial exemption (reference exemption number 10767). Expedited treatment is necessary 

to prevent interruption to 767 production deliveries.

Privileges of the Exemption Outside the United States:

Per 14 CFR 11.81(h), Boeing requests that the privileges of this exemption be extended 

outside the United States. This extension of privileges is necessary for operations based 

within foreign countries having bilateral agreements with the United States accepting 

FAA 14 CFR part 25 as their airworthiness standards for transport category aircraft.

Conclusion:

Boeing is petitioning for a time-limited exemption from the provisions of 14 CFR 

25.901(c)[25-126] and 14 CFR 25.981(a)(3)[25-125] at the system level as they apply to 

the FQIS installed on the 767-300 and 767-300F airplanes for the FQPU parts 

obsolescence change described above. The proposed center fuel tank wire separation, 

FQIS three tank, 750 hour BITE check, and incorporation of NGS for all 767 production 

airplanes will further improve fuel tank safety and reduce fleet safety risks. Exemption is 

requested to apply through the end of 2019 to provide coverage through the end of the 

currently committed 767-300 and -300F production activity. The 767-2C, which will be 

produced beyond 2019, will be fully compliant to these requirements.

Supplemental information

The FAA requested supplemental information from Boeing regarding the estimated date that

service instructions would be available, and an estimated maximum number of airplanes for 

which the exemption would apply that would be produced prior to the end of 2019. Boeing 

responded that the currently estimated date for availability of service instructions (Wire 

Separation Service Bulletin) is August 24, 2015 and will be no later than December 18, 2015.

They stated, “The maximum number of airplanes that would be produced from expiration of the 

current Exemption No. 10767 in May 2016 through the end of 2019 (firm orders) is estimated to 

be 37 – 25 current orders through 2018 with a potential to sell and deliver 12 more freighters in 

2019.”
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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, a summary of it was published 

in the Federal Register on January 20, 2015 (80 FR 2774). We received one comment from the 

National Air Traffic Controllers Association (NATCA) National Safety Committee. The 

commenter does not agree that the requirements of 14 CFR 11.81(e) for granting an extension to 

the original exemption have been met and feels the petitioner did not provide sound justification

showing the extension would be in the public interest. NATCA recommended the FAA not grant 

the extension.

The following paragraphs summarize the relevant information from NATCA’s comment. The 

complete comment is available in Docket No. FAA-2012-1132 on the FDMS website.

NATCA contends that granting a permanent exemption would not provide a level of safety at 

least equal to that provided by the rule from which Boeing seeks the exemption and, therefore,

does not meet the requirement of § 11.81(e) for granting an exemption. NATCA notes that the 

petitioner’s planned changes do not comply with the ignition prevention standards of 

§§ 25.901(c) and 25.981(a). NATCA believes that the design proposed by the petitioner 

represents a significant reduction in the level of safety as compared to a design that would fully 

comply with the rules.

NATCA did not agree with the petitioner’s justification for granting an amendment to the 

original exemption because it is based primarily on the cost of developing a compliant design 

and a statement of no adverse effect on safety because of flammability reduction features 

required by separate regulations. The costs associated with compliance are not a consideration 

for meeting the level of safety criteria in § 11.81(e) for granting an exemption. The FAA’s 2008 

rulemaking required fuel tank flammability reduction in 767 production in addition to a separate 

ignition prevention requirement in § 25.981. Therefore, the commenter contends the 

flammability reduction system should not be a consideration in the public interest argument 

when evaluating extending relief from certain ignition source protection proposed in this 

petition.

NATCA disagrees with the petitioner’s proposal to incorporate a design change that partially 

complies just prior to the original exemption’s May 17, 2016 expiration date for full compliance 

as a means to provide the public interest required by § 11.81(d).

NATCA also asserts that Boeing has produced airplanes with a known unsafe condition with 

regard to FQIS wiring under the original exemption and notes that the petitioner has not provided 

FAA-requested service instructions to mitigate the unsafe condition as required by 14 CFR 21.99 

and 183.69(d). NATCA requested the FAA provide documentation of any enforcement action 

the FAA is taking against the petitioner for failure to provide the required service instructions.

NATCA requested the FAA provide details, including documentation of communication,

regarding any corrective actions the FAA and the petitioner, as well as other design approval 

holders, have established to address unsafe conditions associated with FQIS for the proposed 
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airworthiness directive (AD) for the Boeing Model 757 series airplanes and other airplanes, 

including the 767, with similar FQIS vulnerabilities.

Therefore, NATCA recommended the FAA not grant the petition for extension of the original 

exemption beyond the current expiration date. NATCA requested additional information be

included in the docket.

The FAA’s analysis

The FAA agrees with the petitioner’s statement of public interest for granting the extension of 

the original exemption from May 17, 2016 until the end of production of 767-300F cargo 

airplanes, currently scheduled through December 31, 2019. We partially agree with the 

commenter and have determined granting an extension to the exemption for passenger airplanes 

past the current limit of May 17, 2016 is not in the public interest. In making this determination,

we considered the comment, and we partially agree with the commenter that the extension 

should not be granted because partial wire separation for one fuel tank would not provide a level 

of safety equivalent to direct compliance. If the petitioner intends to continue to offer the 767 

passenger airplane for future production and sales, they should account for the resources, time, 

and cost they would need to bring the airplanes into full compliance in making such 

arrangements. Boeing has been aware of its obligation to address potential fuel tank ignition 

sources associated with its FQIS since at least 2002, when it identified those ignition sources as 

required by Special Federal Aviation Regulation No. 88. The three-year extension provided by 

the current time-limited exemption was adequate to enable Boeing to comply if it intended to do 

so. Based on these considerations, we cannot make a finding that granting an extension for 

passenger airplanes is in the public interest.

We partially agree with the commenter’s request that we not include the flammability reduction 

means (FRM) in our decision to grant the exemption since the system is required by separate 

regulations. The petitioner must incorporate FRM in production to support their U.S. customers’ 

operating rules in 14 CFR 121.1117(b), therefore installation of FRM alone is not sufficient to 

justify granting an exemption. However, meeting the existing requirement for fuel tank FRM by 

inerting the center wing fuel tank on newly produced 767-300F airplanes in combination with 

reducing the risk of fuel tank ignition through partial wire separation and enhanced maintenance 

for the FQIS will provide an adequate level of safety for 767 cargo airplane operations. As stated 

in the original exemption, cargo airplanes are excluded from the requirement to retrofit FRM into 

the existing fleet of transport airplanes. Introduction of 767-300F cargo airplanes that have FRM 

and partial wire separation for the center tank FQIS, which are safer than older cargo airplanes 

that are not required to be retrofitted with FRM, will increase overall fleet safety and is in the 

public interest. Additional public interest considerations include Boeing’s ability to offer the 

767-300F at a price that could result in more sales of airplanes with the safety enhancement of 

FRM, stimulating the economy and reducing cargo shipping costs. We also agree with the 

commenter and did not consider the petitioner’s argument that earlier introduction of airplanes 

modified with design improvements compared to the requirement of the original exemption 

should be considered as part of the public interest analysis. Nevertheless, we do concur with the 

petitioner’s proposal to incorporate these changes, as they would enhance safety as compared to 

the existing design.
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Boeing has confirmed their commitment made in the original exemption to provide the service 

instructions necessary to support modification to the 767 FQIS on in-service airplanes in a timely 

manner. They provided an estimated timeframe of between August 24 and December 18, 2015,

for availability of service instructions that will enhance the safety of existing airplanes in the 

fleet.

The commenter requested the FAA provide additional information regarding any enforcement 

action the FAA is taking against the petitioner for non-compliance to §§ 21.99 and 183.69;

communications with the petitioner on the subject of the NPRM for the 757 FQIS AD; and

information on pending ADs for other models. We have determined these issues are outside the 

scope of the petition for exemption. Information regarding the 757 FQIS AD is provided in the 

docket (FAA-2012-0187) for that action. We note that the NPRM for the 757 FQIS AD identifies 

installation of FRM as a means to effectively mitigate the unsafe condition. Boeing has included 

FRM on all newly-delivered 767 airplanes since 2010, which mitigates the unsafe condition 

associated with FQIS on those airplanes.

The original exemption included discussion and provisions for newly manufactured and inservice airplanes. We have included a provision in this partial grant of exemption that clarifies 

our intent to allow operators to replace FQPUs of in-service airplanes without requiring 

operators to bring those airplanes into full compliance at the expiration of this time-limited 

partial exemption. As discussed earlier, the FQIS on in-service airplanes may be subject to future 

actions resulting from rulemaking to address unsafe conditions.

The FAA’s decision

In consideration of the foregoing, I find that granting a partial extension to the original partial 

grant of exemption for cargo-only airplanes 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, The 

Boeing Company is hereby granted a time-limited exemption from 14 CFR 25.901(c) and 

25.981(a)(3) in order to accomplish the following design changes:

1. Incorporate center fuel tank wire separation, wire shielding, and a 750-hour interval fault 

check of the center tank FQIS on all newly produced 767-300F airplanes; and

2. Optional replacement of the ARINC 429 chip within the FQPU’s IOC cards and the 

BITE card for in-service and production 767-200/-300/-300F/-400ER airplanes.

The following conditions and dates apply:

1. The design changes described in item 1 above must be accomplished within one year of 

the granting of this exemption.

2. Boeing must submit for FAA approval the service instructions modifying the 767 FQIS 

as requested by the FAA in accordance with §§ 21.99 and 183.69 by December 18, 2015.

This exemption will expire on that date unless Boeing has submitted approvable service 

instructions.
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3. The expiration date of May 17, 2016, established in the original exemption continues to 

apply to 767-200/-300/-400ER airplanes, subject to condition 2.

4. This time-limited exemption for newly produced 767-300F airplanes expires on 

December 31, 2019, subject to condition 2.

Upon the expiration dates of this time-limited exemption established in items 3 and 4 above for 

the specified models:

• The FQIS on all newly-produced 767 series airplanes must comply with §§ 25.901(c), 

Amendment 25-46, and 25.981(a)(3), Amendment 25-102, or later amendments; and

• Airplane owners and operators are not required by this exemption to replace FQPUs 

installed as replacement parts on in-service airplanes and may continue to replace FQPUs 

in accordance with each airplane’s type design approved under the conditions of this 

exemption.

All conditions of the original exemption apply.

Issued in Renton Washington, on May 4, 2015.

/s/ Jeffrey E. Duven

Jeffrey E. Duven

Manager, Transport Airplane Directorate

Aircraft Certification Service