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RA-15-04504 The Boeing Company P.O. Box 3707 Seattle, WA 98124-2207



### U.S. Department ofTransportation Docket Operations, M-30 1200 New JerseyAvenue, S.E. Room W12-140, West Bldg. Ground Floor Washington, DC 20590-0001
Subject:

Model: RA Project No.: References:

AD Related: Petition for a Time Limited Exemption from 14 CFR 25.981(a)(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126 pertaining to planned changes for the 767-300 and 767-300F Fuel Quantity Indication System (FQIS) in support ofCertification Plan 15287, "CenterWing Tank Fuel Quantity Indicating System Wire Separation for 74 7-400/400F/767-300/-300F without Nitrogen Generating Systems and Production 767-300F with Nitrogen Generating Systems" 767-300 and 767-300F PS15-0460 a) Limited Time Partial Exemption number 10767, issued May17, 2013. b) Limited Time Partial Exemption number 10767A, issued May 4, 2015. c) Denied Petition for Exemption number 107678, issued Oct 30, 2015 Yes: 04-AD-56 Special Instructions: The BCA Regulatory Administration PA recommends the prime TPM forthe subject be Mr. Tom Thorson. This lettersubmits: (X) Petition for Exemption The Boeing Company respectfully submits the enclosed Petition forAmendment to 

### Exemption 107678from the Title 14 Code of Federal Regulations Part 25.981(a)(3) Amendment 25-125 and 14 CFR 25.901 (c) Amendment 25-126 in support of

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Certification Plan 15287, "CenterWing Tank Fuel Quantity Indicating System Wire Separation for 747-400/400F/767-300/-300F without Nitrogen Generating Systems and Production 767-300F with Nitrogen Generating Systems." Yourtimely cooperation in these matters is greatly appreciated. Boeing respectfully requests this petition for a time limited exemption be approved by December 18, 2015 forthe following reason: If requested relief is not granted the result will be a shutdown ofthe 767 production line on December 18,2015. 

### This letter is sentfor: (X) Regulatory Review/Approval 

### Please contactthis office orthe following individuals ifyou have further questions: (X) ProjectAdministrator (PA): John Grover at (425) 239-9001 

### (X) BCA RegulatoryAdministration 747/767 Program Manager: Nicholas Smith 

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### Douglas M. Lane Director, Regulatory Administration (425) 237-1383, MC 03-56 FAX: (425) 294-9340

Enclosure: Petition for Exemption from 14 CFR 25.981 (a)(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126 pertaining to planned changes for the 767-300 and 767-300F Fuel Quantity Indication System (FQIS)

cc: Name K. 

### Patel A. Lam Sharepoint 

### Yes Yes Comments 6Y-01 BASOO

- LAACOEnclosure RA-15-04504 Page 1of8

Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126 pertaining to planned changes for the 767-300 and 767-300F Fuel Quantity Indication System (FQIS)

Petitioner:

References: Douglas Lane, Director, Regulatory Administration The Boeing Company Boeing Commercial Airplanes PO Box 3707 Seattle, Washington, 98124
a) Limited Time Partial Exemption number 10767, issued May17, 2013 b) Limited Time Partial Exemption number 10767 A, issued May 4, 2015 c) Denied Petition for Exemption number 10767B, issued Oct 30, 2015
The Boeing Company respectfully submits the enclosed Petition for Exemption from the Title 14 Code of Federal Regulations §14 CFR 25.901(c) Amendment 25-126 and 14 CFR 25.981(a)(3) Amendment 25-125

. Section(s) ofthe Regulations from which Relief is sought:
14 CFR 25.901(c) atAmendment 25-126 requires: (c) For each power plant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination offailures willjeopardizethe safe operation ofthe airplane exceptthatthe failure ofstructural elements need not be considered if the probability ofsuch failure is extremely remote.

14 CFR 25.981(a)(3) atAmendment 25-125 requires: (a) No ignition source may be present at each point in the fuel tank orfuel tank system where catastrophic failure could occur due to ignition offuel orvapors. 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 offailures not shown to be extremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely damage must be considered.Enclosure RA-15-04504 Page 2 of8 The Extent of ReliefSoughtand Reason(s): Regulation Compliance requires:
14 CFR 25.901(c) No single failure or Amendment 25-126 malfunction or probable combination offailures will jeopardize safe operation Relief is Necessary because:
Direct compliance would require excessive design changes to incorporate FQPU modifications and Line Replaceable Units (LRU) that result in investment not commensurate with level ofsafety improvement. Changes include thefollowing:



# - Redesign oftheAirplane Wiring System to ensure FQIS wire separation for numerous airplane configurations.



# - Modification ofthe Fuel Quantity Processor Unit (FQPU) and associated connectors.



# - FQIS architecture change and to locate new LRUs on an EE shelf.



# - In-tank component changes (new brackets, potential need for shorter probes, revised in-tankwire harness and retention means).



# - Software changes related to Fuel Tank Gauging Function (to account for capacitance changes ifshorter in-tank probes are required).Enclosure RA-15-04504 Page 3of8 14 CFR An ignition source could not 25.981(a)(3) result from each single Amendment 25-125 failure, from each single failure in combination with each latentfailure condition notshown to be extremely remote, and from all combinations offailures not shown to be extremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely damage must be considered.



### Description ofIssue: Background: Same as above

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 theARINC 429 data. One ofthe microchip components, which are involved with communication to the flight deckand refueling panel, has been out ofproduction forseveral years, and the supply has now become exhausted.
In February 2012 the FQPU supplier informed Boeing thatthe supply ofthis particularARINC 429 chip used on thetwo IOC cards and also on the Built in Test Equipment (BITE) card would run out in late 2012 and thatthere were no sources for procurement ofthe current chip. The supplier initiated a contractwith anotherchip manufacturerto develop a replacement chip to the unchanged requirements ofthe original chip as defined by the supplier's Specification Control Document. The newchip, by requirement, is an identical form-fit-function replacementto the current production chip. In August, 2012, Boeing and the supplier reviewed the existing stores of parts and determined the existing supplywould support production through January2013with a possible extension into March 2013.
In the first exemption (10767) application forthis subject, The Boeing Company (TBC) communicated that ifshowing full compliance to 25.901(c) Amendment Level25-126 and 25.981(a)(3) Amendment Level25-125 forthe FQIS at the system level was required dueto replacing this obsolescent chip with an identical form-fit-function chip, then a significant number ofchangeswould be required to the FQIS intrinsically safe sidewiring. Thefirst exemption (10767) was granted as a time-limited exemption (reference exemption number 10767), expiring in May 17, 2016, afterwhich full compliance ofthe FQIS would be required. In the second exemption ( 10767A) application forthis subject, The Boeing Company communicated that showing full compliance to 25.901(c) Amendment Level25-126 and 25.981(a)(3) Amendment Level25-125 forthe FQIS atthe system level was not economical andEnclosure RA-15-04504 Page4 of 8 had no substantial effect on the safety ofthe fleet since production was going to end in 2019. The second exemption (10767A) was granted as a time-limited exemption, expiring in 2019, afterwhich full compliance ofthe FQIS would be required. But there were several conditions, one ofwhich was thatfor the exemption, for production to not expire, TBC 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. Since the issuance ofthe second time limited exemption, The Boeing Company has been working on the service instructions, the production changes required by May4, 2016, and a fully compliant FQIS in production priorto December 31, 2019.
After receiving Exemption 10767A in mid May 2015, TBC has been working rapidly to meetthe most difficult ofthe conditions, that being condition 2 which reads "Boeing mustsubmitforFAA approvalthe service instructions modifying the 767FQIS as requestedbythe FAA in accordance with§§ 21.99 and 183.69 byDecember 18, 2015. This exemption will expire on that date unless Boeing has submittedapprovable service instructions. In addition, the FAA requires the service instructions be certified through showing compliance by inspection on a candidate (in-service) airplane. TBC putforth the effortto meetthis schedule, but it became apparent as the days passed, that no in-service airplanes would be available during the time before the Exemption 10767A Condition 2 date. TBC developed the certification compliance plans and conformity plans needed to carry out a remote cert demonstration. The plan to do a remote certification to retrofit the wiring on an in-service airplane initially appeared to support the Exemption 10767A timeline, however no freighter airplanes are available due to the heavy delivery usage months prior to year end.
In light ofthese difficulties, The Boeing Company petitioned for a change to Exemption 10767 A to change the commitment dates to July 29, 2016, and 767 production not be made dependent on the SB for the fleet, but ratherthe SB would be issued following production incorporation. This petition was denied in reference c) Exemption No. 10767B issued on Oct 30, 2015. The FAA communicated in that letterthatthe Boeing Companywas not providing sufficiently committed schedules to grantthe extension.
Discussion:
This new petition for a revised time limited exemption is to request a change to the conditions identified in Exemption 10767A. According to the guidance provided by the FAA in the recently denied Exemption 10767B, a committed schedule for the accomplishment ofa remote certification and the submittal ofthe compliance deliverables is required. TBC proposes that 10767 A condition 2 be revised to be May 31, 2016 which will also allowthe production installation to precede the retrofit installation. Boeing will provide evidence (such as contracts with an airline and schedules approved by the Chief Project Engineers and ODA Administrator) ofthe commitmentto meetthis date by December2, 2015. The FAA has agreed to supportthis commitment by also communicating to the airlines the urgency ofcompleting the CWT FQIS wire separation project. The purpose ofthe retrofit project is to address freighters without NGS perthe direction ofthe FAA. The production project is TBC initiated to enhance safety while providing for [previously] the production line to end in 2019with acceptable safety and economics, and now for the production line to install a new FQIS starting by 2019, as the production life has been significantly extended since petitioning for Exemption 10767A.
The previous petitions for a time limited exemption (10767 

### &10767A)were made since full compliance to these rules for the 767 would require extensive system design changes which doEnclosure RA-15-04504 Page 5of8 not substantially improvethe safety ofthe current airplane design, are economically prohibitive given the remaining production ofthe 767-300 and -300F and are not in the public's interest, which was applicable for the known production up to 2019. Based on the granting of Exemption 10767 A onlyforthe 767-300F (and does not applyto the 767-300), The Boeing Company is incorporating significant improvementsto newly produced 767 airplanes starting in February 2016 thatwill increase the level ofsafety by addressing both ignition sources and exposure time aswas proposed. All new production airplanes from February 2016 to 2019 will incorporate design changes similarto the centerfuel tankwire separation being developed by SB 767-28- 0122 which will be required by ADfor all 767 freighters that do not have NGS. These wire separation changes have been and are on schedule to be implemented on all new production airplanes one year afterthe exemption 10767A was granted. This also includesthe Center Wing Tank 750 hour BITE check, similarto instructions forthe centerwing tank provided in a SB 767-28-0118 forfreighters without NGS, and being required byAD.
All newly produced 767 airplanes, since line number 993 in July 2010, address flammability exposure time with the incorporation ofa centertankfuel tankflammability 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 first granted time limited exemption (10767), the FAA stated that "currentfuel tank safety airworthiness standards rely upon a balanced approach ofprecluding ignition sources that could form in the fuel tanks and limiting fuel tankflammability exposure time. The aforementioned fuel tankwire 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. Also, starting in production in 2019, which may include the 767-300, a new and fully compliant FQIS will become a production installation, and so there will be nofurther exemption petitions for767 FQIS.
Thistime limited exemption (TLE) is being soughtforthe no single plus latent (greaterthan extremely remote) as is stated in §25.981(a)(3) and interpreted bythe FAAfor §25.901(c). Exemption is also being soughtforthe non-environmental aspects of§25.901(c) provided by FAA interpretation, and the explicit §25.981(a)(3) requirements ofmanufacturing variability, aging, wear, corrosion, and likely damage, asthese considerations are already covered by factory manufacturing processes, and airline maintenance ofthe type design ofairplane. Exemption is requested to continue to apply through the end of2019to provide coverage for 300F production activity and potential incremental sales. The 767-2C, which will be produced beyond 2019, will be fully compliantto these requirements.
Statement of Public Interest:
In support ofthis fourth petition, Boeing is proposing to continueto address both ignition sources and exposure time in the centertank (NGS on all newly produced airplanes), but differently before and after2019. 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 improvementsto address both ignition sources and exposuretime. Before the petitioned TLE expiration in 2019, all new production airplanes will incorporate design changes similarto the centerfuel tankwire separation being developed by SB 767-28- 0122 which will be required byADfor all767freighters that do not have NGS. These wireEnclosure RA-15-04504 Page 6 of8 separation changeswill be implemented on all new production airplanes one year afterthe exemption (10767A) was granted and will be madewith the guidance of28-AWL-09. In addition, as identified in 10767 A, the 

### Cwrtank, the 750 hour BITE check, similarto instructions for the centertank provided in SB 767-28-0118 forfreighters without NGS, and being required byAD. These changes will address ignition sources on all newly produced 767 airplanes.
All newly produced 767 airplanes, since line number 993 in July2010, addressflammability exposuretime with the incorporation ofa centertankfuel tankflammability reduction system, the Nitrogen Generation System (NGS). This addresses exposuretime as required for all 767 in-service passenger airplanes and adds flammability reduction systemsfor all freighter airplanes since line number 993. By addressing both exposuretime and ignition sources, newly produced 767 airplanes until 2019 will use a balanced approach and achieved a higher level ofsafety than any in-service 767 airplanes. Design changesthatwould be required to be fully compliantwould not provide a significant benefit or increased level ofsafety for new production airplanes that incorporatethe proposed wire separation, BITE check, and havethe Nitrogen Generation System (NGS) installed. Although this is so, Boeing will be providing a new FQIS that is fully compliant as it is now economicallyjustifiable dueto increased production airplanes beyond 2019. Until and if production ended in 2019, the costs associated with these changeswould not be commensuratewith the increased level ofsafety and would be economically prohibitive given the relatively small numberofadditional production aircraftthatwould be burdened with these costs. These changes would include thefollowing:

• Newsystem architecture and extensive airplanewiring changes to ensure adequatewire separation throughoutthe fuel quantity indication system. • In-tank component changes (new brackets, potential need for shorter probes, revised intankwire harness and retention means). • Software changes related to Fuel Tank Gauging Function and Safety function ifshorter probes are required.
Finally, the associated design proposal in support ofthis petition for exemption will implement centertank FQIS and FLSS limited wire separation and FQIS BITE check earlierthan other alternatives, on line number 1094for FQIS wire separation (factory rollout on 2/1/16) and on line number 1096 (factory rollout on 3/10/16) for FLSS wire separation. TBC will briefthe FAA on a monthly basis until this project is complete. This will provide importantenhancements to airplane safety earlier, and on more production airplanes. Please note, relief is not being sought for 767-300F or 300 production after2019, orfor the 767-2C, which will be fully compliantwith a new FQIS, and is anticipated to be the only minor model produced forthe next several decades.
A fully compliant FQIS will be incorporated into production priorto the expiration ofthe TLE in 2019. Granting this time limited exemption is in the public interestfor the aforementioned reasons and will:
1. Promote continued production ofthe 767 airplane after May 17, 2016, and to end in 2019, when an exemption will no longer be needed. All production airplanes will address fuel tanksafetywith incorporation ofwire separation, scheduled health checks, and a fuel tank inerting system (NGS). A grant ofexemption will also provide significantEnclosure RA-15-04504 Page 7of8 economic benefitto the public in the form ofcontinued 767 production and support efficient, safe operation by our customers by providing a consistentfleet configuration.
2. The proposal for this exemption request ofimplementing the centertank FQIS limited wire separation and FQIS BITE check can be accomplished on the earlier granted schedule, (scheduled May 4, 2016,one year afterthe exemption 10767 A was granted) enhancing safety earlier on more airplanes.
3. Enable the new FQIS project (wire separation) to continue undisrupted by the possibility of Exemption 10767A expiration, which would disrupt 767 production.

Statement of No Adverse Effect on Safety:
The replacement ofthe existing ARINC 429 chip with the new replacement chip does not adversely affectthe safety ofthe current system. There is no threat to fuel tank ignition from the lOGs 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 effect on the safety ofthe system and has no impactto airplane safety.
The 767 FQIS was found to be compliantto §25.901 (c) during airplane type certification forthe FQIS change in 1992 and since then Boeing has completed the SFAR88 safety assessment and has increased the airplane fuel system safetywith installation ofa hot short protectorforthe densitometer and with installation ofa NGS for the centerfuel tanks. The proposed change to address the previous time limited exemption has no impact on any ofthe SFAR88 related assessments.
Even priorto the implementation of NGS which further reduces any risk, the Boeing assessment was that the risks forthe 767 FQIS installation were extremely improbable, which is the typical industry and CFR §25.1309 standard for an acceptable safety for systems.
The Boeing approach to incorporate design changes to add centerfuel tankfuel wire separation, a 750 hour BITE check, and installation of NGS on all newly produced 767 airplanes will provide for an improved safety margin overthe existing, approved in-service fleet. These changes are scheduled to be done one year after grant of 10767 A exemption, thereby incorporating changes to more airplanes than possible underthe existing time limited exemption. After2019, the proposal is to incorporate a new FQIS into production, which will be compliant to the present interpretation ofthe 25.901(c), and 25.981(a)(3) [A125] Requestto Waive Publication and Comment:
Given the time-sensitive nature ofthis 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 safetyassociated aspects related to this system have been fully vetted in the publicforum as part of the SFAR88 project and the two previous time-limited partial exemptions (reference exemption number 10767 and 10767 A). Expedited treatment is necessary to prevent interruption to 767 production deliveries.Enclosure RA-15-04504 Page 8of 8 Privileges ofthe Exemption Outsidethe United States:
Per 14 CFR 11.81(h), Boeing requests thatthe privileges ofthis exemption be extended outside the United States. This extension ofprivileges is necessary for operations based within foreign countries having bilateral agreementswith the United States accepting FAA 14 CFR part 25 as their airworthiness standards fortransport 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] atthe system level asthey applyto the FQIS installed on the 767-300 and 767-300F airplanesforthe FQPU parts obsolescence change described above. We are also requesting thatthe service instructions submittal date be extended to May 31, 2016. The FAA has also agreed to supportthis commitment by also communicating to the airlines the urgency ofcompleting the CWT FQIS wire separation project. TBC will report on the progress ofthe 767 improvements on a monthly basis until the projects are complete. The proposed centerfuel tank FQIS wire separation, a 750 hour BITE check, and incorporation of NGS forall 767 production airplanes will further improvefuel tank safety and reduce fleet safety risks. Exemption is continued to be requested to applythrough the end of2019, as the FQIS in 767 production will be compliantto these regulations afterthattime. The 767-2C, which will be produced beyond 2019, will befully complianttothese requirements.
Summaryto be published inthe 

### FederalRegister:
PETITIONER:
SECTION OF 14CFRAFFECTED:

DESCRIPTION OF RELIEF SOUGHT: Boeing Commercial Airplanes
14 CFR 25.901(c) Amendment 25-126 and 14 CFR 25.981(a)(3) Amendment 25-125

The Boeing Company 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] and exemption 10767A atthe system level as they applyto the FQIS and FLSS installed on the 767-300 and 767-300F airplanesthrough the end of2019, thereby providing relief until the end of2019forthe current 767-300F production and anticipated 767-300 production. TBC is also petitioning for an extension of condition 2 of 10767Afrom December 18, 2015to May 31, 2016.