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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 125. The regulation as currently written: 

§25.981 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 improbable. The effects of manufacturing 

variability, aging, wear, corrosion, and likely 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, there are no practical 

means to provide dual fault tolerance or 

three layers of protection 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 dual 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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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 structural 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 ignition of fuel vapors. 

Note: “Fuel tank structure” includes “Permanent Systems Supporting Structure” which are 

permanently attached structural parts (such as brackets and component housings not typically 

removed during the life of an airplane) that are used to support system elements. 

- “Fuel tank systems,” or “systems,” include tubing, components, and wiring that are penetrating, 

located within, or connected to the fuel tanks in a way that a critical 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 three reliable, independent, and 

effective protection features to prevent ignition sources. After Amendment 102 and 125 were 

introduced, Boeing has found that it is impractical to provide 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 was 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 provides guidance for an applicant to apply for an Exemption 

to 25.981(a)(3) with respect to lightning protection if it is also shown to be impractical. Per FAA 

Policy Statement PS-ANM-25.981-02, 

“...The petitioner should show that all practical measures have been taken to meet the 

requirements of § 25.981(a)(3) for the fuel tank structure and systems. For the design 

features for which an exemption is sought, the petitioner should show what potentially 

compliant changes were examined, and what design changes were ruled out based on 

impracticality.”
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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Boeing notes that under this Policy Statement, “practicality” is a balance of available means, 

economic viability, and proportional benefit to safety. 

The FAA also noted in this Policy Statement that 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 required to ensure protection against catastrophic fuel 

tank ignition events. The FAA acknowledged that the concepts of impracticality discussed with 

respect to structures can, in principle, be extended to systems as well. 

The PS-ANM-25.981-02 FAA policy provides the following alternate requirements 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 design feature if: 

a) Fault tolerance is shown to be impractical for that feature, and 

b) Fuel tank vapor ignition because 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 airworthiness limitations, mandatory maintenance actions (i.e., 

inspections), or CDCCLs, necessary to preclude the development of unsafe 

conditions due to non-fault-tolerant lightning protection 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-mandatory programs such as Baseline Zonal 

inspection program, Corrosion Prevention and Control Program (CPCP), etc., 

are going to be used to support the robustness of the overall inspection program, 

these programs must become mandatory and must be included in the 

Airworthiness Limitations section of the airplane’s Instructions for Continued 

Airworthiness. 

c) Incorporating into applicable airplane maintenance documents, including the 

manufacturer’s structural repair manual, caution information that identifies the 

lightning protection features of the fuel system design to minimize the potential 

for inadvertent damage or disruption of these features. 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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(5) An analysis must be performed to show that the airplane’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 protection features because of manufacturing 

variability, aging, wear, corrosion, and likely damage.” 

In line with the PS-ANM-25.981-02 FAA policy, Boeing has identified categories of features that 

are considered impractical when the design has been 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 could have adverse safety consequences due to the complexity of 

the design by introducing new failure conditions. 

The list of items below are fuel tank structure and fuel tank system design considerations found to be 

impractical because there are no technically available 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 inspection 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 eliminate 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 installation. Increasing the number of in-tank inspection intervals 

would also have a potential unintended consequence of damaging the ignition protection 

features or other components inside 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 inspection when not needed to show the design is safe, is considered 

impractical due to the potential adverse safety consequences, maintenance, and operational 

economic impacts on airlines. 

2. Additional Sealant on fasteners: For areas of the design where a single layer of sealant 

provides one protective feature, a second layer of sealant (cap seals, fillet seals, etc) could be 

added to fastener installations but will typically not provide an added layer of protection due 

to susceptibility to common cause failure with the existing sealant protection layer. The 

additional sealant also reduces structural inspectability for cracks and corrosion, potentially 

reducing overall fleet safety, and would result in increased weight, fuel burn and emissions. 

Based on the common cause failure risk and adverse 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 enclosed fuel vapor space, which would pose an 

additional vapor ignition threat during a lightning attachment and thus does not increase 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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safety. This would also increase weight which 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 possible to produce monolithic composite or aluminum wings in 

dimensions that the 777-9 would require to eliminate the need for electrical bonding at 

structural joints. Also, monolithic aluminum designs would reduce structural crack tolerance. 

For composites, using adhesives only instead 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 tolerance will be shown without it, additional 

sealant over some fasteners subject to direct attachment, structural joints subject to conducted 

currents, and systems installation subject to induced voltages and currents during a lightning 

strike, has been determined to be impractical. Boeing will perform an assessment of these 

installations representative of the 777-9 design and will show that even with a fault present, 

the installations will not cause an ignition source during a lightning 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 commensurate safety benefit to the public 

considering the significant weight 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 ensure sufficient voltage standoff is maintained 

between adjacent in-tank systems and systems to structure or ground plane. Boeing will 

provide an assessment to demonstrate that in these areas adding a layer of protection does not 

provide a proportional benefit of safety. Boeing will show that the additional layer is 

unnecessary to ensure that a fuel tank ignition event is not expected in the life of the fleet and 

unnecessarily increases weight, fuel burn, production, maintenance and environmental cost. 

If any other proprietary design consideration is found to be impractical to meet the requirements of 

14 CFR 25.981(a)(3), this detailed information will be provided in a separate submittal to the FAA. 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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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 identified in the 777-9 design 

process, Boeing will also provide a list of features that are considered impractical to mitigate the loss 

of fault tolerance, as well as an assessment demonstrating the probability of a fuel vapor ignition due 

to these failures is numerically extremely improbable or qualitatively not expected 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 design to provide practical structural and systems 

lightning protection. A separate Impracticality 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 wing structure including improvements over design features that have 

been used in existing in service designs (787-8/-9). For structural aspects, Boeing proposes to 

demonstrate that most of 777-9 structural lightning protection designs are fault tolerant, and 

additional features (where possible) are considered impractical because they do not provide a 

proportional safety benefit. For fuel tank systems aspects, Boeing proposes to provide a fault tolerant 

design. In many areas, systems protection may provide 3 or more protection features. Boeing will 

provide substantiation to show which systems design protection features that could provide a third 

protection layer are impractical. As part of the Impracticality Assessment, 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, Appendix M. The aspects of NGS performance with 

respect to compliance to 14 CFR 25.981 will be covered in the 777-9 Fuel Systems Certification 

Plan. 

Boeing will provide the following with respect 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 systems lightning protection. Boeing will utilize reliable design 

protection features which minimize the occurrence of failures in service. Boeing will 

utilize reliable manufacturing processes to minimize the risk of errors in aircraft 

manufacturing which could affect the lightning protection features. Instructions for 

Continued Airworthiness including Critical Design Configuration Control Limitations 

(CDCCLs) will be developed and included in the certification documentation to retain 

the lightning protection features. A complete analysis of manufacturing processes 

and maintenance procedures will be part of the 777-9 Fuel System Lightning 

Protection System Safety Assessment. 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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Policy Requirement 2 – Provide fault tolerant lightning protection: 

Structural Aspects: 

Boeing will show that the fuel tank structure for the model 777-9 wing will provide 

reliable fault tolerant lightning protection. A detailed Failure Modes and Effects 

Analysis (FMEA) including a qualitative assessment 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 primary means to substantiate fault tolerance for 

both direct attachment and conducted current lightning threats. The permanent 

supporting structure installations 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 the fuel tanks when exposed to lightning 

threats. This analysis or testing will include failure mode conditions to demonstrate a 

fault tolerant design for both direct attachment and conducted current lightning 

threats. 

System Aspects: 

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

reliable and fault tolerant. A detailed Failure 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 systems that result from indirect effects and 

conducted current lightning threats. Boeing 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 lightning 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 been that 14 CFR 25.981 compliance must be 

shown at an overall system level, thus the 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 protection results in additional weight, fuel 

burn, maintenance and/or manufacturing cost, and does not provide proportional 

safety benefit, adding additional features would be impractical. 
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Policy Requirement 3 – Demonstrate safety for limited number of non-fault 

tolerant designs:

Boeing’s intent is to provide a fault tolerant design for both fuel tank structure and 

fuel tank systems. 

For the limited areas in which single or cascading failures could result in loss of all 

protection features and 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 and 787 wing are made out of composite. The 

777-9 wing will use similar or enhanced lightning protection features as compared to 

those used on the 787 wing. 

Non-fault tolerant designs are not expected for fuel tank systems lightning 

protection. Most lightning protection features for systems on the 777-9 are similar 

those used in other Boeing aircraft with composite and/or aluminum wings. Service 

experience on the existing Boeing aircraft commercial fleet with aluminum wings has 

shown these protection features to be robust, reliable, and independent. 

Policy Requirement 4 – Provide lightning protection maintenance information: 

Where necessary (e.g. critical protection features) CDCCLs, which identify the 

critical characteristics of the lightning protection features of the fuel tank systems and 

fuel tank structure, will be defined in order to minimize the potential for inadvertent 

damage or disruption to the features. The CDCCLs will provide restoration 

requirements if protection features are disturbed during maintenance or repairs. This 

information will be included in the Airworthiness Limitations section of the 

Instructions for Continued Airworthiness. An additional CDCCL will require a visual 

inspection per Airplane Maintenance Manual Fuel Tank Closure procedure any time 

the tank area is exited after maintenance or alteration. 

Non-fault tolerant features: The design objective is to have no fuel tank structural 

non-fault tolerant lightning protection features, however the detailed design and 

assessment is not complete. If necessary, Airworthiness Limitations Inspections 

(ALIs) will be included to ensure that no unsafe conditions will develop. The ALIs 

will be included in the Airworthiness Limitations section of the Instructions for 

Continued Airworthiness. No non-fault tolerant features for systems aspects are 

expected. 

Fault tolerant features: Maintenance and/or inspections to validate the in-service 

integrity of fault tolerant fuel tank systems and fuel tank structure lightning protection 

features that are likely to degrade will be included in the Airworthiness Limitations 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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section of the Instructions for Continued 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 System Lightning Protection System Safety Assessment. 

Dedicated maintenance and/or inspections 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 Continued 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 lightning protection features have 

never been included in the MRBR. Fuel tank system lightning protection features for 

past certification projects have utilized the MRBR development process for scheduled 

maintenance, but this process has been shown 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 features, and the MRBR 

derived maintenance would provide 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 programs may be utilized to verify the reliability of fuel 

system lightning protection features. However, 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 Maintenance Manuals will include instructions 

to minimize the risk that alternations (repairs) 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. 
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Petition for Exemption from 14 CFR 25.981(a)(3) Amendment 25-125

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Policy Requirement 5 - Analysis of design, manufacturing and maintenance 

procedures: 

Boeing will perform an analysis to show that the design and manufacturing processes 

include all practical measures to prevent, detect and correct failures of structural and 

systems lightning protection features due to manufacturing 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 analysis of the manufacturing processes, repair 

procedures, and the reliability of the lightning protection features will be part of the 

777-9 Fuel System Lightning Protection System Safety Assessment. 

Statement of Public Interest 

Boeing is working to improve the 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. Practical measures to ensure an acceptable level of 

safety will be utilized. Additional features to directly meet the rule are not available or are 

impractical as they would potentially have adverse safety consequences, add significant cost, weight, 

increased emissions and maintenance to the airplane without a commensurate safety benefit. 

Additional lightning protection features could add complexity and/or inhibit the ability to inspect the 

structure which could impact overall airplane safety. 

Requiring the 777-9 to attempt to directly comply with this rule is not feasible with available 

technology in some areas. In other areas it would significantly increase the operational costs (e.g. 

fuel burn due to increased weight) and maintenance 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, certify, and manufacture the airplane. The new 777-9 

will replace older, less fuel efficient aircraft reducing 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 tolerant 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 service flight hours with no 

lightning related events. The design features on the 777-9 for structural lightning protection 

are similar or further improved on those provided on the 787 and are based on state of the art 

technology. 
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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 report, Task Group 1 Service History / Fuel 

Tank Safety Level Assessment). The first was in 1963, which led to the development of 

lightning protection standards for fuel tanks. The second and last event was in 1976 and also 

resulted in improvements in fuel 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 fleet history since 1976 shows current Boeing wing designs have sufficient 

protection against lightning induced fuel tank ignition events. 

Request to ‘Waive Publication and Comment’ 

Boeing requests to waive the requirement for publication and comment. Boeing believes 

there is good cause to be granted a waiver due to the fact that the FAA previously found a 

grant of exemption was in the 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 certification 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 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. The 777-9 is 

intended for the global market place. 

Conclusion 

Boeing is petitioning for an exemption from 14 CFR 25.981(a)(3) at amendment 125 for fueltank structural and systems lightning protection. Granting this exemption will allow Boeing 

to provide a competitive product without compromising safety. Per FAA Policy memo PSANM-25.981-02, Boeing will show that certain existing design features that are considered 

impractical have potential adverse 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 acceptable 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.