RA-15-04483 Page 1 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

1 Name and Address of the Petitioner

Douglas M. Lane, Director, Commercial Airplanes The Boeing Company

PO Box 3707 MC 03-56 Seattle, Washington, 98124-2207

Section(s) of the Regulations from which Relief is Sought:

Boeing is petitioning for an Exemption to 14 CFR 25.981(a)(3) for fuel tank structure and systems lightning protection for the 777-9 (Project Number PS13-1000). The subject regulation section is unchanged between Amendment Level 102 and 1 25. The regulation as currently written:

§25.981 Fuel tank ignition prevention. (a) No ignition source may be present at each poin t in the fuel tank or fuel tank system where catastrophic failure could occur due to ignition of fuel or va pors. This must be shown by:

(3) Demonstrating that an ignition source could not result from ea ch 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 ex tremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and lik ely damage must be considered.

The Extent of Relief Sought and Reason(s) Regulation Requires: Relief is Necessary because:

14 CFR 25.981(a)(3)

Amendment 25-125 Compliance to 14 CFR 25.981(a)(3) with regards to lightning protection for both fuel tank systems and fuel tank structure (fastener and joints) would require dual fault tolerance or three independent layers of protection. Boeing has concluded that for fuel tank systems, basic airframe structural fasteners / joints, and permanent systems supporting structure, th ere are no practical means to provide dual fault tolerance or three layers of pr otection in some

locations as follows:

A) Thousands of fasteners are used in the wing of the 777-9. There is no current technology to obtain triple redundant means of lightning protection in some

locations. B) In areas of the design (both structure and systems) where triple redundant means of protection could be provided, the additional complexity of incorporating such means over dualRA-15-04483 Page 2 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

2 redundancy is unnecessary to ensure the risk of a catastrophic event is extremely improbable and would have significant impact on operational, maintenance and production costs, while not providing a commensurate safety benefit.

For this Exemption Request, definitions for the following terms apply:

- “Fuel tank structure” includes struct ural members of the fuel tank such as airplane skins, joints, ribs, spars, stringers, and associated fasteners, brackets, coatings and sealant where a lightning

strike could lead to i gnition of fuel vapors.

Note: “Fuel tank structure” includes “Permane nt Systems Supporting Structure” which are permanently attached structural parts (such as brackets and component housings not typically removed during the life of an airplane) th at are used to support system elements.

- “Fuel tank systems,” or “systems,” include tubi ng, components, and wiring that are penetrating, located within, or connected to th e fuel tanks in a way that a cri tical lightning strike could lead to ignition of fuel vapors.

Description of Issue

Compliance to 14 CFR 25.981(a)(3) would require a design with th ree reliable, independent, and effective protection features to prevent igni tion sources. After Amendment 102 and 125 were introduced, Boeing has found that it is impractical to pr ovide dual fault tolerant features for fuel tank structural joints using state-of -the-art technology for both composite and traditional aluminum fuel tanks. As a result, Boeing has petitioned and wa s granted an Exemption on the 747-8/8F (Exemption No. 10174) and on the 767-2C (Exemption No. 10884 was granted), and a special condition on the 787 (25-414-SC). A petition for Exemption has also been requested for the 737MAX, pending approval by the FAA at the time of this request.

Policy Statement PS-ANM-25.981-02 provi des guidance for an applicant to apply for an Exemption to 25.981(a)(3) with respect to light ning protection if it is also shown to be impractical. Per FAA Policy Statement PS-ANM-25.981-02,

“...The petitioner should show that all practic al measures have been taken to meet the requirements of § 25.981(a)(3) fo r the fuel tank structure an d systems. For the design features for which an exempti on is sought, the petitioner sh ould show what potentially compliant changes were examined, and what design changes were ruled out based on impracticality.”RA-15-04483 Page 3 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

3 Boeing notes that under this Policy Statement, “p racticality” is a balance of available means, economic viability, and proporti onal benefit to safety.

The FAA also noted in this Policy Statement th at in some cases 25.981(a)(3) compliant fuel tank system designs relative to lightning protection exceed the level of safety required for other aspects of airplane systems design, and exceed what is requir ed to ensure protection against catastrophic fuel tank ignition events. The FAA acknowledged that th e concepts of impracticality discussed with respect to structures can, in principl e, be extended to systems as well.

The PS-ANM-25.981-02 FAA policy provides the followi ng alternate requireme nts in lieu of full compliance to ensure that an acceptable level of safety is provided:

“(1) The fuel tank structure and systems must be designed and installed to prevent catastrophic fuel vapor ignition due to lightning.

(2) The fuel tank structure and systems lightning protection design must be fault tolerant for failures that result in lightning-related ignition sources.

(3) Fault tolerance is not required for any specific de sign feature if:

a) Fault tolerance is shown to be im practical for that feature, and b) Fuel tank vapor ignition b ecause of that feature and all other non-fault tolerant features, when their fuel tank vapor ignition event probabilities are combined, is shown to be extremely improbable.

(4) Inspections or other procedures must be established to prevent development of lightningrelated ignition sources within the fuel tank structure and systems, for example:

a) Identifying airworthines s limitations, mandatory maintenance actions (i.e., inspections), or CDCCLs, necessary to preclude the development of unsafe conditions due to non-fault-toler ant lightning prot ection features; b) Including sampling programs, maintenance, and/or inspections for fault-tolerant lightning protection features in the manufacturer’s recommended airplane maintenance program;

Note: If inspections from non-mandator y programs such as Baseline Zonal inspection program, Corrosion Preventi on and Control Program (CPCP), etc., are going to be used to support the robus tness of the overall inspection program, these programs must become mandatory and must be included in the Airworthiness Limitations section of the airplane’s Instruct ions for Continued

Airworthiness.

c) Incorporating into applicable airplane maintenance documents, including the manufacturer’s structural repair manual, c aution information t hat identifies the lightning protection features of the fuel system design to minimize the potential for inadvertent damage or di sruption of these features.RA-15-04483 Page 4 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

4 (5) An analysis must be perf ormed to show that the airp lane’s design, its manufacturing processes, and the Airworthiness Limitations section of its Instructions for Continued Airworthiness include all practical measures to prevent and detect and correct, failures of fuel tank structure and systems lightning pr otection features bec ause of manufacturing variability, aging, wear, corrosion, and likely damage.”

In line with the PS-ANM-25.981-02 FAA policy, Boeing ha s identified categories of features that are considered impractical when the design has b een shown to be safe by providing fault tolerant features and when an additional layer of protection does not provide a commensurate level of safety. Additionally, adding another layer co uld have adverse safety conseque nces due to the complexity of the design by introducing new failure conditions.

The list of items below are fuel ta nk structure and fuel tank system design considerations found to be impractical because there are no technically avai lable means, they introduce more risk than mitigation, and/or they have negative impact on production, operational, and maintenance costs without a commensurate safety benefit.

1. Fastener/Sealant inspection : To eliminate the latency in the fastener or sealant related protective features, an inspecti on interval could be applied to monitor the health of each fastener or the protective sealant. However, this inspection interval would need to be accomplished after every revenue flight to e liminate latency per FAA guidance, or on the order of monthly inspections to statistically be significant. Additionally, the wing of the 777-9 has thousands of fasteners and many locations where sealant may need to be applied as a protective feature. Most of the protective features of the fastener are impossible to be visually inspected after inst allation. Increasing the number of in-tank inspec tion intervals would also have a potential unintended cons equence of damaging th e ignition protection features or other components in side the fuel tanks. Requiring in service inspections where possible would require significant maintenance time to inspect each fastener or sealant. As such, fastener or sealant inspecti on when not needed to show the design is safe, is considered impractical due to the potential adverse safe ty consequences, mainte nance, and operational economic impacts on airlines.

2. Additional Sealant on fasteners : For areas of the design wher e a single layer of sealant provides one protective feature, a second layer of sealant (cap seal s, fillet seals, etc) could be added to fastener installations but will typical ly not provide an added layer of protection due to susceptibility to common cau se failure with the existing sealant protection layer. The

additional sealant also reduces structural inspectability for cracks and corrosion, potentially reducing overall fleet safety, a nd would result in increased wei ght, fuel burn and emissions.

Based on the common cause failure risk and adve rse safety consequences, added weight and reduced structural inspection capability, this feature is considered impractical when the design can already be shown safe.

3. Fuel tank bladders or double walled fuel tanks : Adding fuel tank bladders or secondary

fuel tank walls would result in a new enclos ed fuel vapor space, which would pose an additional vapor ignition threat during a lightning attachment and thus does not increaseRA-15-04483 Page 5 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

5 safety. This would also increase weight whic h would increase fuel burn and emissions, plus

reduces usable fuel tank volume which reduces range. The bladders also inhibit structural inspectability inside the tank.

4. Fastener Free Wing Structure : Structure that does not have any fasteners would not be susceptible to lightning protection faults associated with fasteners but is not necessarily dual fault tolerant. It is not po ssible to produce monolithic com posite or aluminum wings in dimensions that the 777-9 would require to eliminate the need for electrical bonding at structural joints. Also, monolithic aluminum de signs would reduce structural crack tolerance. For composites, using adhesives only inst ead of fasteners to bond major components represents a radical departure from established metallic and composite wing primary structure experience.

The following design features, were determined to be impractical due to lack of proportional safety benefit, increased weight, increased fuel burn, increased emissions, and reduced inspectability during maintenance:

 Sealing : For areas of the design where fault tolera nce will be shown without it, additional sealant over some fasteners subject to direct attachment, structur al joints subject to conducted currents, and systems installation subject to induced voltages and curr ents during a lightning strike, has been determined to be impractical . Boeing will perform an assessment of these installations representati ve of the 777-9 design and will show that even with a fault present,

the installations will not cause an ignition source during a lig htning event. Sealant can inhibit structural inspections to identify potential safety issues, complicate assembly processes that increase the possibility of errors, and potentially affect the health of mechanics due to preparing surfaces and applying sealant in confined spaces. Boeing concluded that further mitigation (i.e. covering structural and systems installations with sealant) to provide dual fault tolerance would not provide a co mmensurate safety benefit to the public considering the significant wei ght and associated fuel costs plus carbon emissions, aircraft production costs and operator maintenance impacts.

 Separation/Isolation Features : Additional design features could be provided for further redundancy in separation or isolation; to ensu re sufficient voltage standoff is maintained between adjacent in-tank systems and system s to structure or ground plane. Boeing will provide an assessment to demonstrate that in th ese areas adding a layer of protection does not provide a proportional benefit of safety. Boei ng will show that the additional layer is unnecessary to ensure that a fuel tank ignition ev ent is not expected in the life of the fleet and unnecessarily increases weight , fuel burn, production, maintena nce and environmental cost.

If any other proprietary design cons ideration is found to be impractic al to meet the requirements of 14 CFR 25.981(a)(3), this detailed information will be provided in a separate submittal to the FAA.RA-15-04483 Page 6 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

6 Boeing will also submit to the FAA, detailed information on any faults identified for which the design is not single fault tolerant. For any non-fault tolerant features identi fied in the 777-9 design process, Boeing will also provide a list of features that are considered impract ical to mitigate the loss of fault tolerance, as well as an assessment demo nstrating the probability of a fuel vapor ignition due to these failures is numerically extremely improbable or qualitatively not expe cted in the life of the

fleet.

Proposed Risk Mitigation

As discussed in the FAA Policy Statement, Boeing will submit detailed proprietary information to

the FAA about the measures taken in the 777-9 desi gn to provide practical structural and systems lightning protection. A separate Impracticalit y Assessment certification deliverable will be provided. In general, the 777-9 lightning protection features are based on state of the art industry design practices for composite wi ng structure including improvements over design features that have been used in existing in service designs (787-8/-9 ). For structural aspect s, Boeing proposes to

demonstrate that most of 777-9 structural lightning protection designs are fault tolerant, and additional features (where possi ble) are considered impractical because they do not provide a proportional safety benefit. For fuel tank systems as pects, Boeing proposes to provide a fault tolerant design. In many areas, systems protection may provi de 3 or more protection features. Boeing will provide substantiation to show which systems desi gn protection featur es that could provide a third protection layer are impractical. As part of the Impracticality Assessmen t, Boeing will take credit for the occurrence of a lightning strike and a flammable tank to demonstrate that an additional layer for some locations does not provide a proportional safety benefit.

Boeing will comply with 14 CFR 25.981(b) at Amendment 25-125. A flammability exposure assessment will be provided. The main tanks as well as the Center Wing Tank (CWT) on the 777-9 will use an inerting system designed to meet the applicable requirements. The CWT will meet the flammability exposure criteria of Part 25, Appe ndix M. The aspects of NGS performance with respect to compliance to 14 CFR 25.981 will be c overed in the 777-9 Fuel Systems Certification

Plan.

Boeing will provide the following with respec t to each of the 5 Policy requirements:

Policy Requirement 1 - Prevent catastrophic fuel vapor ignition due to lightning:

In summary, Boeing will implement in the design all practical measures for fault tolerant structural and syst ems lightning protection. Boei ng will utilize reliable design protection features which minimize the occu rrence of failures in service. Boeing will utilize reliable manufacturing processes to minimize the risk of errors in aircraft manufacturing which could aff ect the lightning protection features. Instructions for

Continued Airworthiness incl uding Critical Design Configur ation Control Limitations (CDCCLs) will be developed and included in the certification documentation to retain the lightning protection features. A comple te analysis of manufacturing processes and maintenance procedures will be pa rt of the 777-9 Fuel System Lightning Protection System Safety Assessment.RA-15-04483 Page 7 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

7 Policy Requirement 2 – Provide fault tolerant lightning protection:

Structural Aspects:

Boeing will show that the fuel tank struct ure for the model 777-9 wing will provide reliable fault tolerant ligh tning protection. A detailed Failure Modes and Effects Analysis (FMEA) including a qualitative a ssessment of all known failure modes will be provided as part of the compliance documentation. Analysis, design review, and/or use of test data will be the primar y means to substantiate fault tolerance for

both direct attachment and conducted curre nt lightning threats. The permanent supporting structure installati ons will also be analyzed as part of the safety assessment to ensure that the requirements of the policy statement are met.

Where analysis or testing is performed, the data will show that the installations will not produce any ignition sources inside th e fuel tanks when exposed to lightning threats. This analysis or testing will incl ude failure mode conditi ons to demonstrate a fault tolerant design for both direct a ttachment and conducted current lightning

threats.

System Aspects:

Boeing will show that the lightning protec tion design for fuel tank systems will be

reliable and fault tolerant. A detailed Fa ilure Modes and Effects Analysis (FMEA) including assessment of all known failure modes will be provided as part of the compliance documentation. An assessment will be done to determine the magnitude of voltages and currents in fuel tank system s that result from indirect effects and conducted current lightning threats. Boei ng will show that the protection means provided mitigate these threats, and are reliable over the life of the airplane.

In many locations the fuel tank system li ghtning protection may be more than single fault tolerant, and thus potentially compliant to 14 CFR 25.981(a)(3) at these specific locations. However, FAA guidance has b een that 14 CFR 25.981 compliance must be shown at an overall system level, thus th e system itself would still not be directly compliant unless all areas of protection were dual fault tolerant. Where practical dual fault tolerance can be employed for fuel tank system lightning protection, it will be included. However where the additional prot ection results in additional weight, fuel burn, maintenance and/or manufacturing cost, and does not provide proportional safety benefit, adding additional features would be impractical.RA-15-04483 Page 8 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

8 Policy Requirement 3 – Demonstrate safety for limited number of non-fault tolerant designs:

Boeing’s intent is to provide a fault tole rant design for both fu el tank structure and fuel tank systems.

For the limited areas in which single or cas cading failures could result in loss of all protection features a nd providing fault tolerance is impractical, a safety assessment will be done. The safety assessment will show that the summed risk of all structural non-fault tolerant lightning related fuel tank ignition threats is numerically extremely improbable or qualitatively not anticipated to occur during the entire operational life of all 777-9 airplanes. The 777-9 an d 787 wing are made out of composite. The 777-9 wing will use simi lar or enhanced light ning protection features as compared to those used on the 787 wing.

Non-fault tolerant design s are not expected for fu el tank systems lightning protection. Most lightning pr otection features for syst ems on the 777-9 are similar those used in other Boeing ai rcraft with composite and/ or aluminum wings. Service experience on the existing Bo eing aircraft commercial fleet with aluminum wings has shown these protection features to be robust, reliable, and independent.

Policy Requirement 4 – Provide lightnin g protection maintenance information:

Where necessary (e.g. critical protection features) CDCCLs, which identify the critical characteristics of the lightning prot ection features of the fuel tank systems and fuel tank structure, will be defined in orde r to minimize the potential for inadvertent damage or disruption to the features . The CDCCLs will provide restoration requirements if protection features are distur bed during maintenance or repairs. This

information will be included in the Ai rworthiness Limitations section of the

Instructions for Continued Airworthiness. An additional CDCCL will require a visual inspection per Airplane Maintenance Manua l Fuel Tank Closure procedure any time

the tank area is exited afte r maintenance or alteration.

Non-fault tolerant features: The design object ive is to have no fuel tank structural non-fault tolerant lightning protection features, howeve r the detailed design and assessment is not complete. If necessar y, Airworthiness Limitations Inspections (ALIs) will be included to ensure that no unsafe conditions will develop. The ALIs

will be included in the Airworthiness Lim itations section of the Instructions for

Continued Airworthiness. No non-fault to lerant features for systems aspects are expected.

Fault tolerant features: Maintenance and/or inspections to validate the in-service integrity of fault tolerant fuel tank system s and fuel tank structure lightning protection features that are likely to degrade will be included in the Airworthiness LimitationsRA-15-04483 Page 9 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

9 section of the Instructions for Conti nued Airworthiness. The likelihood of degradation and the reliability of protection features will be qualitatively established in support of compliance and certification. The qualitative reliability analysis will be included in the 777-9 Fuel Sy stem Lightning Protection System Safety Assessment. Dedicated maintenance and/or inspecti ons are not required for those lightning protection features that are considered highly or inherently reliable.

No periodic maintenance or inspections for structural lightning protection have been identified at this time, however the assessment is not complete; additional maintenance requirements will be included in the Airworthiness Limitations section

of the Instructions for Conti nued Airworthiness if necessary.

Development of scheduled maintenance per guidance in AC 121.22, “Maintenance Review Boards, Maintenance Type Boards, and OEM/TCH Recommended

Maintenance Procedures” for inclusion in the 777-9 Maintenance Review Board Report (MRBR), will not be used for fuel tank system and fuel tank structure lightning protection features. Fuel tank structural lightni ng protection features have

never been included in the MRBR. Fuel ta nk system lightning prot ection features for past certification projects have utilized the MRBR devel opment process for scheduled maintenance, but this process has been s hown to have an extremely high correlation to the Airworthiness Limitation Inspection development process. Boeing therefore considers the maintenance derived for the Airworthiness Limitations as adequate coverage to ensure the safety of the lightning protection f eatures, and the MRBR derived maintenance would pr ovide no additional benefit to the maintenance program of the 777-9 and may lead to unnecessary fuel tank entries that have the potential to introduce unintended consequences to the fuel system.

Sampling and surveillance program s may be utilized to verify the reliability of fuel system lightning protection features. Howe ver, at this time the detailed design and reliably assessment is not complete. If a sampling or surveillance program is required, it will be submitted in support of compliance and certification.

Repairs: The Structural Repair Manual will include instructions to minimize the risk that alterations (repairs) will affect fuel tank structural lightning protection. The SRM will include CDCCL references (equivalent to Cautions). Also note that as discussed above, a CDCCL will identify an Airplane Maintenance Manual procedure to perform a visual inspection before exiting any tank area where maintenance, inspection or repair has been performed. In addition to the CDCCLs for fuel tank system lightning protection, Airplane Mainte nance Manuals will include instructions to minimize the risk that alternations (repa irs) will affect fuel tank system lightning protection.

Sub-paragraph 25.981(d) is pursuant to 25.981(a) . Since this exemption applies to 25.981(a)(3), the above reflects how Boeing at this time intends to address 25.981(d) for lightning protection features as well as meet the related policy requirements.RA-15-04483 Page 10 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

10 Policy Requirement 5 - Analysis of de sign, manufacturing and maintenance procedures: Boeing will perform an analysis to show th at the design and manufacturing processes include all practical measures to prevent, de tect and correct failure s of structural and systems lightning protection f eatures due to manufacturi ng variability, aging, wear, corrosion and likely damage. As noted for Requirement 4, the continued airworthiness program will include appropriate CDCCL and the SRM repair procedures will be established to retain the lightning protection features throughout the life of the airplane. A complete analys is of the manufacturing processes, repair procedures, and the reliability of the lightni ng protection features wi ll be part of the 777-9 Fuel System Lightning Protecti on System Safety Assessment.

Statement of Public Interest

Boeing is working to improve th e efficiency of the 777 model by a redesign. The 777-9 has an all new composite wing and new engine to improve fuel burn and to reduce community noise over the 777-300ER model. For lightning protection, the 777-9 will have enhanced protection in the fuel tanks from sparking due to a lightning event. Prac tical measures to ensure an acceptable level of safety will be utilized. Additional features to di rectly meet the rule are not available or are impractical as they would potential ly have adverse safety consequen ces, add significant cost, weight, increased emissions and maintenance to the airplane without a commensurate safety benefit. Additional lightning protection features could add comp lexity and/or inhibit the ability to inspect the structure which could impact overall airplane safety.

Requiring the 777-9 to attempt to directly comply w ith this rule is not f easible with available technology in some areas. In other areas it woul d significantly increase the operational costs (e.g. fuel burn due to increased weight) and maintenan ce costs with no commensurate increase in safety, rendering the 777-9 to be of lesser value. Direct compliance would also significantly increase costs incurred by The Boeing Company to design, certif y, and manufacture the airplane. The new 777-9 will replace older, less fuel efficient aircraft re ducing the public expense for fuel consumed in air travel and freight delivery. Therefore, Boeing believes that it is in the public interest for the FAA to grant this exemption.

Statement of No Adverse Effect on Safety

Per the Policy Statement PS-ANM -25.981-02, a fault to lerant design provides an acceptable level of safety. With current design practices for systems lightning protection, Boeing aircraft designs have accumulated in excess of 800 million revenue se rvice flight hours with no lightning related events. The design features on the 777-9 for structur al lightning protection are similar or further improved on those provide d on the 787 and are based on state of the art technology.RA-15-04483 Page 11 of 11 Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

11 Prior to current designs practices, there were 2 commercial jet transport hull loss events which are believed to have been caused by lightning strikes (reference ARAC Report: 1998 ARAC Fuel tank Harmonization Working Group re port, Task Group 1 Se rvice History / Fuel Tank Safety Level Assessment). The first was in 1963, which led to the de velopment of lightning protection standards for fuel tanks. Th e second and last even t was in 1976 and also resulted in improvements in fu el tank lightning protection. The hours accumulated since the last event represent over 8 times the hours accumulated with earlier designs through 1976.

The accident free flee t history since 1976 shows current Boei ng wing designs have sufficient protection against lightning indu ced fuel tank ignition events.

Request to ‘Waive Publication and Comment’

Boeing requests to waive the requirement fo r publication and comment. Boeing believes there is good cause to be granted a waiver du e to the fact that the FAA previously found a grant of exemption was in th e public interest for the same fuel tank lightning protection compliance to CFR 25.981(a)(3) issue on the 747-8/8F (BDCO Project No PS05-0212 & PS05-0211; Exemption No. 10174) and on the 767-2C (BDCO Project No PS09-0863; Exemption 10884). Additionally, Boeing has also submitted a Petition for Exemption based on the revised PS-ANM-25.981-02 policy for the 737 MAX (Docket No. FAA-2014-1042). Most importantly, the certific ation approach described in this Petition follows the requirements of Policy memo PS-ANM-25.981-02 to provide a fault tolerant design for both structures and systems.

Privileges of the Exemption Outside the United States

Per 14 CFR 11.81(h), Boeing request s that the privileges of th is exemption be extended

outside the United States. This extension of privileges is necessary for operations based within foreign countries havi ng bilateral agreements with the United States accepting FAA 14 CFR part 25 as their airworthiness standards for transport category aircraft. The 777-9 is intended for the global market place.

Conclusion

Boeing is petitioning for an exemption from14 CFR 25.981(a)(3) at amendment 125 for fueltank structural and systems lightning protecti on. Granting this exemption will allow Boeing to provide a competitive product without comp romising safety. Per FAA Policy memo PSANM-25.981-02, Boeing will show that certain exis ting design features that are considered impractical have potential a dverse safety consequences, add significant cost, weight, increased emissions, and maintenance to the airplane without a proportional safety benefit. The proposed design for the 777-9 will provide an acceptabl e level of safety against lightning-induced fuel-tank ignition and will be shown to comply with the alternative requirements provided in the FAA policy memo PS-ANM-25.981-02.