52698 Federal Register / Vol. 74, No. 197 / Wednesday, October 14, 2009 / Proposed Rules 

would expire when the prepaid 

assessments have been exhausted or 

when remaining prepaid assessments 

are returned to the institution after 

December 30, 2014. 

Respondents: Insured depository 

institutions. 

Number of responses: 75 during the 

first year; 25 the second year and 10 in 

the final year. 

Frequency of response: Occasional. 

Average number of hours to prepare 

a response: 2 hours. 

Total annual burden: 150 hours the 

first year; 50 hours the second year; and 

20 hours in the third year. 

By order of the Board of Directors. 

Dated at Washington, DC, this 9th day of 

October 2009. 

Federal Deposit Insurance Corporation. 

Robert E. Feldman, 

Executive Secretary. 

[FR Doc. E9–24822 Filed 10–9–09; 4:15 pm] 

BILLING CODE 6714–01–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. NM415; Notice No. 25–09–11– 

SC] 

Special Conditions: Boeing Model 787– 

8 Airplane; Lightning Protection of 

Fuel Tank Structure To Prevent Fuel 

Tank Vapor Ignition 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed special 

conditions. 

SUMMARY: This action proposes special 

conditions for the Boeing Model 787–8 

airplane. This airplane will have novel 

or unusual design features when 

compared to the state of technology 

envisioned in the airworthiness 

standards for transport category 

airplanes. The Boeing Model 787–8 

airplane will incorporate a fuel tank 

nitrogen generation system (NGS) that 

actively reduces flammability exposure 

within the main fuel tanks significantly 

below that required by the fuel tank 

flammability regulations. Among other 

benefits, this significantly reduces the 

potential for fuel vapor ignition caused 

by lightning strikes. The applicable 

airworthiness regulations do not contain 

adequate or appropriate safety standards 

for this design feature. These proposed 

special conditions contain the 

additional safety standards that the 

Administrator considers necessary to 

establish a level of safety equivalent to 

that established by the existing 

airworthiness standards. 

DATES: We must receive your comments 

by November 30, 2009. 

ADDRESSES: You must mail two copies 

of your comments to: Federal Aviation 

Administration, Transport Airplane 

Directorate, Attention: Rules Docket 

(ANM–113), Docket No. NM415, 1601 

Lind Avenue, SW., Renton, Washington 

98057–3356. You may deliver two 

copies to the Transport Airplane 

Directorate at the above address. You 

must mark your comments: Docket No. 

NM415. You may inspect comments in 

the Rules Docket weekdays, except 

Federal holidays, between 7:30 a.m. and 

4 p.m. 

FOR FURTHER INFORMATION CONTACT: 

Mike Dostert, FAA, ANM–112, 

Transport Airplane Directorate, Aircraft 

Certification Service, 1601 Lind 

Avenue, SW., Renton, Washington 

98057–3356; telephone (425) 227–2132; 

facsimile (425) 227–1149. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite interested persons to take 

part in this rulemaking by sending 

written comments, data, or views. The 

most helpful comments reference a 

specific portion of the special 

conditions, explain the reason for any 

recommended change, and include 

supporting data. We ask that you send 

us two copies of written comments. 

We will file in the docket all 

comments we receive as well as a report 

summarizing each substantive public 

contact with FAA personnel concerning 

these proposed special conditions. You 

may inspect the docket before and after 

the comment closing date. If you wish 

to review the docket in person, go to the 

address in the ADDRESSES section of this 

notice between 7:30 a.m. and 4 p.m., 

Monday through Friday, except Federal 

holidays. 

We will consider all comments we 

receive by the closing date for 

comments. We will consider comments 

filed late if it is possible to do so 

without incurring expense or delay. We 

may change the proposed special 

conditions based on comments we 

receive. 

If you want the FAA to acknowledge 

receipt of your comments on this 

proposal, include with your comments 

a pre-addressed, stamped postcard on 

which the docket number appears. We 

will stamp the date on the postcard and 

mail it back to you. 

Background 

On March 28, 2003, The Boeing 

Company applied for an FAA type 

certificate for its new Boeing Model 

787–8 passenger airplane. The Boeing 

Model 787–8 airplane will be a new 

design, two-engine turbo-jet transport 

category airplane with a two-aisle cabin 

configuration. The maximum takeoff 

weight will be 484,000 pounds, and it 

will carry a maximum of 381 

passengers. 

Type Certification Basis 

Under provisions of 14 CFR 21.17, 

Boeing must show that Boeing Model 

787–8 airplanes (hereafter referred to as 

‘‘the 787’’) meet the applicable 

provisions of 14 CFR part 25, as 

amended by Amendments 25–1 through 

25–117, with three exceptions. Sections 

25.809(a) and 25.812 will remain as 

amended by Amendment 25–115, and 

§ 25.981, which will be as amended by 

Amendment 25–125 in accordance with 

14 CFR 26.37. 

If the Administrator finds that the 

applicable airworthiness regulations 

(i.e., part 25) do not contain adequate or 

appropriate safety standards for the 787 

because of novel or unusual design 

features, special conditions are 

prescribed under provisions of 14 CFR 

21.16. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the 787 must comply with 

the fuel vent and exhaust emission 

requirements of 14 CFR part 34 and the 

noise certification requirements of 14 

CFR part 36. Finally, the FAA must also 

issue a finding of regulatory adequacy 

under § 611 of Public Law 92–574, the 

‘‘Noise Control Act of 1972.’’ 

Special conditions, as defined in 14 

CFR 11.19, are issued in accordance 

with § 11.38 and become part of the type 

certification basis in accordance with 

§ 21.17(a)(2). 

Special conditions are initially 

applicable to the model for which they 

are issued. Should the type certificate 

for that model be amended later to 

include any other model that 

incorporates the same or similar novel 

or unusual design features, the special 

conditions would also apply to the other 

model under § 21.101. 

Novel or Unusual Design Features 

The proposed 787 will have a fuel 

tank NGS that is intended to control fuel 

tank flammability. This NGS is designed 

to provide a level of performance that 

will reduce the warm day fleet average 

wing fuel tank flammability 

significantly below the maximum wing 

fuel tank flammability limits set in 

§ 25.981(b), as amended by Amendment 

25–125. This high level of wing fuel 

tank NGS performance is an unusual 

design feature not envisioned at the 


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1The memorandum may be viewed at: http://

www.airweb.faa.gov/Regulatory_and_Guidance_

Library/rgPolicy.nsf/0/12350AE62D393B7A862

575C300709CA3?OpenDocument&Highlight=anm112-08-002. 

time the regulations in the proposed 787 

certification basis were promulgated. 

Existing Regulations 

The certification basis of the 787 

includes § 25.981, as amended by 

Amendment 25–125, as required by 

§ 26.37. This amendment includes the 

ignition prevention requirements in 

§ 25.981(a), as amended by Amendment 

25–102, and it includes specific 

limitations on fuel tank flammability in 

§ 25.981(b) as amended by Amendment 

25–125. (Section 25.981(c) contains an 

alternative to meeting paragraph (b)— 

vapor ignition mitigation—that is not 

applicable to the proposed 787 design.) 

Ignition Source Prevention 

Section 25.981(a)(3) requires 

applicants to show that an ignition 

source in the fuel tank system could not 

result from any single failure, from any 

single failure in combination with any 

latent failure condition not shown to be 

extremely remote, or from any 

combination of failures not shown to be 

extremely improbable. This requirement 

was originally adopted in Amendment 

25–102 and was based on the 

assumption that fuel tanks are always 

flammable. This requirement defines 

three types of scenarios that must be 

addressed in order to show compliance 

with § 25.981(a)(3). The first scenario is 

that any single failure, regardless of the 

probability of occurrence of the failure, 

must not cause an ignition source. The 

second scenario is that any single 

failure, regardless of the probability of 

occurrence, in combination with any 

latent failure condition not shown to be 

at least extremely remote, must not 

cause an ignition source. The third 

scenario is that any combination of 

failures not shown to be extremely 

improbable must not cause an ignition 

source. Demonstration of compliance 

with this requirement would typically 

require a structured, quantitative safety 

analysis. Design areas that have any 

latent failure conditions typically would 

be driven by these requirements to have 

multiple fault tolerance, or ‘‘triple 

redundancy.’’ This means that ignition 

sources are still prevented even after 

two independent failures. 

Flammability Limits 

Section 25.981(b) states that no fuel 

tank fleet average flammability exposure 

may exceed 3 percent of the 

flammability exposure evaluation time 

calculated using the method in part 25, 

Appendix N, or the fleet average 

flammability of a fuel tank within the 

wing of the airplane being evaluated, 

whichever is greater. If the wing is not 

a conventional unheated aluminum 

wing, the analysis must be based on an 

assumed equivalent construction 

conventional unheated aluminum wing. 

In addition, for fuel tanks that are 

normally emptied during operation and 

that have any part of the tank located 

within the fuselage contour, the fleet 

average flammability for warm days 

(above 80°F) must be limited to 3 

percent as calculated using the method 

in part 25, Appendix M. 

Application of Existing Regulations 

Inappropriate Due to Impracticality 

Since the promulgation of 

§ 25.981(a)(3), as amended by 

Amendment 25–102, the FAA has 

conducted certification projects in 

which applicants found it impractical to 

meet the requirements of that regulation 

for some areas of lightning protection 

for fuel tank structure. Partial 

exemptions were issued for these 

projects. These same difficulties exist 

for the 787 project. 

The difficulty of designing multiplefault-tolerant structure, and the 

difficulty of detecting failures of hidden 

structural design features in general, 

makes compliance with § 25.981(a)(3) 

uniquely challenging and impractical 

for certain aspects of the electrical 

bonding of structural elements. Such 

bonding is needed to prevent 

occurrence of fuel tank ignition sources 

from lightning strikes. The effectiveness 

and fault tolerance of electrical bonding 

features for structural joints and 

fasteners is partially dependent on 

design features that cannot be 

effectively inspected or tested after 

assembly without damaging the 

structure, joint, or fastener. Examples of 

such features include a required 

interference fit between the shank of a 

fastener and the hole in which the 

fastener is installed, metal foil or mesh 

imbedded in composite material, a 

required clamping force provided by a 

fastener to pull two structural parts 

together, and a required faying surface 

bond between the flush surfaces of 

adjacent pieces of structural material 

such as in a wing skin joint or a 

mounting bracket installation. In 

addition, other features that can be 

physically inspected or tested may be 

located within the fuel tanks, therefore, 

it is not practical to inspect for failures 

of those features at short intervals. 

Examples of such failures include 

separation or loosening of cap seals over 

fastener ends and actual structural 

failures of internal fasteners. This 

inability to practically detect failures of 

structural design features critical to 

lightning protection results in any such 

failures that occur remaining in place 

for a very long time, and possibly for the 

remaining life of the airplane, prior to 

detection. 

Accounting for such long failure 

latency periods in the system safety 

analysis required by § 25.981(a)(3) 

would require multiple fault tolerance 

in the structural lightning protection 

design. As part of the design 

development activity for the 787, Boeing 

has examined possible design 

provisions to provide multiple fault 

tolerance in the structural design to 

prevent ignition sources from occurring 

in the event of lightning attachment to 

the airplane in critical locations. Boeing 

has concluded from this examination 

that providing multiple fault tolerance 

for some structural elements is not 

practical. Boeing has also identified 

some areas of the proposed 787 design 

where it is impractical to provide even 

single fault tolerance in the structural 

design to prevent ignition sources from 

occurring in the event of lightning 

attachment after a single failure. The 

FAA has reviewed this examination 

with Boeing in detail and has agreed 

that providing fault tolerance beyond 

that in the proposed 787 design for 

these areas would be impractical. 

As a result of the 787 and other 

certifications projects, the FAA has now 

determined that compliance with 

§ 25.981(a)(3) is impractical for some 

areas of lightning protection for fuel 

tank structure, and that application of 

§ 25.981(a)(3) to those design areas is 

therefore inappropriate. The FAA plans 

further rulemaking to revise 

§ 25.981(a)(3). The FAA plans to issue 

special conditions or exemptions, when 

appropriate, for certification projects in 

the interim. This is discussed in FAA 

Memorandum ANM–112–08–002, 

Policy on Issuance of Special 

Conditions and Exemptions Related to 

Lightning Protection of Fuel Tank 

Structure, dated May 26, 2009.1

Application of Existing Regulations 

Inappropriate Due to Compensating 

Feature That Provides Equivalent Level 

of Safety 

Section 25.981(b) sets specific 

standards for fuel tank flammability as 

discussed above under ‘‘Flammability 

Limits.’’ Under that regulation, the fleet 

average flammability exposure of wing 

main tanks on the 787 may not exceed 

3 percent of the flammability exposure 

evaluation time calculated using the 

method in part 25, Appendix N, or the 

fleet average flammability of a wing 

main tank within an equivalent 


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52700 Federal Register / Vol. 74, No. 197 / Wednesday, October 14, 2009 / Proposed Rules 

construction conventional unheated 

aluminum wing fuel tank, whichever is 

greater. If it is assumed that a 787 

equivalent conventional unheated 

aluminum wing fuel tank would not 

exceed a fleet average flammability time 

of 3 percent, the actual composite 

airplane wing fuel tank design would be 

required to comply with the 3 percent 

fleet average flammability standard. 

However, the proposed 787 design 

includes a wing tank NGS that will also 

be shown to meet the additional, more 

stringent warm day average 

flammability standard in part 25, 

Appendix M, which is only required for 

normally emptied fuel tanks with some 

part of the tank within the fuselage 

contour. 

Since the proposed wing tank NGS on 

the 787 provides performance that 

meets part 25, Appendix M, the FAA 

has determined that the risk reduction 

provided by this additional performance 

will provide compensation for some 

relief from the ignition prevention 

requirements of § 25.981(a)(3). 

In determining the appropriate 

amount of relief from the ignition 

prevention requirements of § 25.981(a), 

the FAA considered the original overall 

intent of Amendment 25–102, which 

was to ensure the prevention of 

catastrophic events due to fuel tank 

vapor explosion. The proposed special 

conditions are intended to achieve that 

objective through a prescriptive 

requirement that fault tolerance (with 

respect to the creation of an ignition 

source) be provided for all structural 

lightning protection design features 

where providing such fault tolerance is 

practical, and through a performancebased standard for the risk due to any 

single failure vulnerability that exists in 

the design. In addition, for any 

structural lightning protection design 

features for which Boeing shows that 

providing fault tolerance is impractical, 

the proposed special conditions would 

require Boeing to show that a fuel tank 

vapor ignition event due to the summed 

risk of all non-fault-tolerant design 

features is extremely improbable. 

Boeing would be required to show that 

this safety objective is met by the 

proposed design using a structured 

system safety assessment similar to that 

currently used for demonstrating 

compliance with §§ 25.901 and 25.1309. 

Discussion of the Proposed 

Requirements 

Given these novel design features, and 

the compliance challenges noted earlier 

in this document, the FAA has 

determined that application of 

§ 25.981(a)(3) is inappropriate in that it 

is neither practical nor necessary to 

apply the ignition source prevention 

provisions of § 25.981(a)(3) to the 

specific fuel tank structural lightning 

protection features of the 787. However, 

without the § 25.981(a)(3) provisions, 

the remaining applicable regulations in 

the 787 certification basis would be 

inadequate to set an appropriate 

standard for fuel tank ignition 

prevention. Therefore, in accordance 

with provisions of § 21.16, the FAA is 

proposing that, instead of § 25.981(a)(3), 

alternative fuel tank structural lighting 

protection requirements be applied to 

fuel tank lightning protection features 

that are integral to the airframe structure 

of the 787. These alternative 

requirements are intended to provide 

the level of safety intended by 

§ 25.981(a)(3), based on our recognition, 

as discussed above, that a highly 

effective NGS for the fuel tanks makes 

it unnecessary to assume that the fuel 

tank is always flammable. As discussed 

previously, the assumption that the fuel 

tank is always flammable was part of the 

basis for the ignition prevention 

requirements of § 25.981(a)(3). 

One resulting difference between 

these proposed special conditions and 

the § 25.981(a)(3) provisions they are 

meant to replace is the outcome being 

prevented—fuel vapor ignition versus 

an ignition source. These proposed 

special conditions acknowledge that the 

application of fuel tank flammability 

performance standards will reduce fuel 

tank flammability to an extent that it is 

appropriate to consider the beneficial 

effects of flammability reduction when 

considering design areas where it is 

impractical to comply with 

§ 25.981(a)(3). 

One of the core requirements of the 

proposed special conditions is a 

prescriptive requirement that structural 

lightning protection design features 

must be fault tolerant. (An exception 

wherein Boeing can show that providing 

fault tolerance is impractical, and 

associated requirements, is discussed 

below.) The other core requirement is 

that Boeing must show that the design, 

manufacturing processes, and 

airworthiness limitations section of the 

instructions for continued airworthiness 

include all practical measures to 

prevent, and detect and correct, failures 

of structural lightning protection 

features due to manufacturing 

variability, aging, wear, corrosion, and 

likely damage. The FAA has determined 

that, if these core requirements are met, 

a fuel tank vapor ignition event due to 

lightning is not anticipated to occur in 

the life of the airplane fleet. This 

conclusion is based on the fact that a 

critical lightning strike to any given 

airplane is itself a remote event, and on 

the fact that fuel tanks must be shown 

to be flammable for only a relatively 

small portion of the fleet operational 

life. 

For any non-fault-tolerant features 

proposed in the design, Boeing must 

show that eliminating these features or 

making them fault tolerant is 

impractical. The requirements and 

considerations for showing it is 

impractical to provide fault tolerance 

are described in FAA Memorandum 

ANM–112–08–002. This requirement is 

intended to minimize the number of 

non-fault tolerant features in the design. 

For areas of the design where Boeing 

shows that providing fault tolerant 

structural lighting protection features is 

impractical, non-fault-tolerant features 

will be allowed provided Boeing can 

show that a fuel tank vapor ignition 

event due to the non-fault-tolerant 

features is extremely improbable when 

the sum of probabilities of those events 

due to all non-fault-tolerant features is 

considered. Boeing will be required to 

submit a structured, quantitative 

assessment of fleet average risk for a fuel 

tank vapor ignition event due to all nonfault-tolerant design features included 

in the design. This will require 

determination of the number of nonfault tolerant design features, estimates 

of the probability of the failure of each 

non-fault-tolerant design feature, and 

estimates of the exposure time for those 

failures. This analysis must include 

failures due to manufacturing 

variability, aging, wear, corrosion, and 

likely damage. 

It is acceptable to consider the 

probability of fuel tank flammability, 

the probability of a lightning strike to 

the airplane, the probability of a 

lightning strike to specific zones of the 

airplane (for example, Zone 2 behind 

the nacelle, but not a specific location 

or feature), and a distribution of 

lightning strike amplitude in performing 

the assessment provided the associated 

assumptions are acceptable to the FAA. 

The analysis must account for any 

dependencies among these factors, if 

they are used. The assessment must also 

account for operation with inoperative 

features and systems, including any 

proposed or anticipated dispatch relief. 

This risk assessment requirement is 

intended to ensure that an acceptable 

level of safety is provided given the 

non-fault-tolerant features in the 

proposed design. 

Part 25, Appendix N, as adopted in 

Amendment 25–125, in conjunction 

with these proposed special conditions, 

constitutes the standard for how to 

determine flammability probability. In 

performing the safety analysis required 

by these proposed special conditions, 


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Federal Register / Vol. 74, No. 197 / Wednesday, October 14, 2009 / Proposed Rules 52701 

relevant § 25.981(a)(3) compliance 

guidance is still applicable. Appropriate 

credit for the conditional probability of 

environmental or operational conditions 

occurring is normally limited to those 

provisions involving multiple failures, 

and this type of credit is not normally 

allowed in evaluation of single failures. 

However, these proposed special 

conditions would allow consideration of 

the probability of occurrence of 

lightning attachment and flammable 

conditions when assessing the 

probability of structural failures 

resulting in a fuel tank vapor ignition 

event. 

The FAA understands that lightning 

protection safety for airplane structure 

is inherently different from lightning 

protection for systems. We intend to 

apply these special conditions only to 

structural lightning protection features 

of fuel systems. We do not intend to 

apply the alternative standards used 

under these special conditions to other 

areas of the airplane design evaluation. 

Proposed Requirements Provide 

Equivalent Level of Safety 

In recognition of the unusual design 

feature discussed above, and the 

impracticality of requiring multiple 

fault tolerance for lightning protection 

of certain aspects of fuel tank structure, 

the FAA has determined that an 

equivalent level of safety to direct 

compliance with § 25.981(a)(3) will be 

achieved for the 787 by applying these 

proposed requirements. The FAA 

considers that, instead of only 

concentrating on fault tolerance for 

ignition source prevention, significantly 

reducing fuel tank flammability 

exposure in addition to preventing 

ignition sources is a better approach to 

lightning protection for the fuel tank. In 

addition, the level of average fuel tank 

flammability achieved by compliance 

with these special conditions is low 

enough that it is not appropriate or 

accurate to assume in a safety analysis 

that the fuel tanks may always be 

flammable. 

Section 25.981(b), as amended by 

Amendment 25–125, sets limits on the 

allowable fuel tank flammability for the 

787. Paragraph 2(a) of these proposed 

special conditions applies the more 

stringent standard for warm day 

flammability performance applicable to 

normally emptied tanks within the 

fuselage contour from § 25.981(b) and 

part 25, Appendix M, to the wing tanks 

of the 787. 

Because of the more stringent fuel 

tank flammability requirements in these 

special conditions, and because the 

flammability state of a fuel tank is 

independent of the various failures of 

structural elements that could lead to an 

ignition source in the event of lightning 

attachment, the FAA has agreed that it 

is appropriate in this case to allow 

treatment of flammability as an 

independent factor in the safety 

analysis. The positive control of 

flammability and the lower flammability 

that is required by these special 

conditions exceeds the minimum 

requirements of § 25.981(b). This offsets 

a reduction of the stringent standard for 

ignition source prevention in 

§ 25.981(a)(3), which assumes that the 

fuel tank is flammable at all times. 

Given the stringent requirements for 

fuel tank flammability, the fuel vapor 

ignition prevention and the ignition 

source prevention requirements in these 

special conditions will prevent ‘‘* * * 

catastrophic failure * * * due to 

ignition of fuel or vapors.’’, as stated in 

§ 25.981(a). Thus, the overall level of 

safety achieved by these special 

conditions is considered equivalent to 

that which would be required by 

compliance with § 25.981(a)(3) and (b). 

Applicability 

These proposed special conditions are 

applicable to the 787–8. Should Boeing 

apply at a later date for a change to the 

type certificate to include another 

model incorporating the same novel or 

unusual design features, these proposed 

special conditions would apply to that 

model as well. 

Conclusion 

This action affects only certain novel 

or unusual design features of the 787. It 

is not a rule of general applicability. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

The authority citation for these 

special conditions is as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701, 

44702, 44704. 

The Proposed Special Conditions 

Accordingly, the Federal Aviation 

Administration (FAA) proposes the 

following special conditions as part of 

the type certification basis for The 

Boeing Model 787–8 airplane. 

1. Definitions 

Most of the terms used in Special 

Condition No. 2, Alternative Fuel Tank 

Structural Lightning Protection 

Requirements, either have the common 

dictionary meaning or are defined in AC 

25.1309–1A, System Design and 

Analysis, dated June 21, 1988. 

The following definitions are the only 

terms intended to have a specialized 

meaning when used in Special 

Condition No. 2.: 

(a) Basic Airframe Structure. Includes 

design elements such as structural 

members, structural joint features, and 

fastener systems including airplane 

skins, ribs, spars, stringers, etc., and 

associated fasteners, joints, coatings, 

and sealant. Basic airframe structure 

may also include those structural 

elements that are expected to be 

removed for maintenance, such as 

exterior fuel tank access panels and 

fairing attachment features, provided 

maintenance errors that could 

compromise associated lightning 

protection features would be evident 

upon an exterior preflight inspection of 

the airplane and would be corrected 

prior to flight. 

(b) Permanent Systems Supporting 

Structure. Includes static, permanently 

attached structural parts (such as 

brackets) that are used to support 

system elements. It does not include any 

part intended to be removed, or any 

joint intended to be separated, to 

maintain or replace system elements or 

other parts, unless that part removal or 

joint separation is accepted by the FAA 

as being extremely remote. 

(c) Manufacturing Variability. 

Includes tolerances and variability 

allowed by the design and production 

specifications as well as anticipated 

errors or escapes from the 

manufacturing and inspection 

processes. 

(d) Extremely Remote. Conditions that 

are not anticipated to occur to each 

airplane during its total life, but which 

may occur a few times when 

considering the total operational life of 

all airplanes of one type. Extremely 

remote conditions are those having an 

average probability per flight hour on 

the order of 1 × 10¥7 or less, but greater 

than on the order of 1 × 10¥9. 

(e) Extremely Improbable. Conditions 

that are so unlikely that they are not 

anticipated to occur during the entire 

operational life of all airplanes of one 

type. Extremely improbable conditions 

are those having an average probability 

per flight hour of the order of 1 × 10¥9

or less. 

2. Alternative Fuel Tank Structural 

Lightning Protection Requirements 

For lightning protection features that 

are integral to fuel tank basic airframe 

structure or permanent systems 

supporting structure, as defined in 

Special Condition No. 1, Definitions, for 

which the Boeing Company shows and 

the FAA finds compliance with 

§ 25.981(a)(3) to be impractical, the 

following requirements may be applied 


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52702 Federal Register / Vol. 74, No. 197 / Wednesday, October 14, 2009 / Proposed Rules 

in lieu of the requirements of 

§ 25.981(a)(3): 

(a) The Boeing Company must show 

that the airplane design meets the 

requirements of part 25, Appendix M, as 

amended by Amendment 25–125, for all 

fuel tanks installed on the airplane. 

(b) The Boeing Company must show 

that the design includes at least two 

independent, effective, and reliable 

lightning protection features (or sets of 

features) such that fault tolerance to 

prevent lightning-related ignition 

sources is provided for each area of the 

structural design proposed to be shown 

compliant with these special conditions 

in lieu of compliance with the 

requirements of § 25.981(a)(3). Fault 

tolerance is not required for any specific 

design feature if: 

(1) for that feature, providing fault 

tolerance is shown to be impractical, 

and 

(2) fuel tank vapor ignition due to that 

feature and all other non-fault-tolerant 

features, when their fuel tank vapor 

ignition event probabilities are summed, 

is shown to be extremely improbable. 

(c) The applicant must perform an 

analysis to show that the design, 

manufacturing processes, and 

airworthiness limitations section of the 

instructions for continued airworthiness 

include all practical measures to 

prevent, and detect and correct, failures 

of structural lightning protection 

features due to manufacturing 

variability, aging, wear, corrosion, and 

likely damage. 

Issued in Renton, Washington, on 

September 24, 2009. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. E9–24652 Filed 10–13–09; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 71 

[Docket No. FAA–2009–0858; Airspace 

Docket No. 09–ASW–22] 

Proposed Amendment of Class E 

Airspace; Llano, TX 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: This action proposes to 

amend Class E airspace at Llano, TX. 

Additional controlled airspace is 

necessary to accommodate new 

Standard Instrument Approach 

Procedures (SIAPs) at Llano Municipal 

Airport, Llano, TX. This action would 

also update the geographic coordinates 

of Llano Municipal Airport to coincide 

with the FAAs National Aeronautical 

Charting Office. The FAA is taking this 

action to enhance the safety and 

management of Instrument Flight Rules 

(IFR) operations for SIAPs at Llano 

Municipal Airport. 

DATES: 0901 UTC. Comments must be 

received on or before November 30, 

2009. 

ADDRESSES: Send comments on this 

proposal to the U.S. Department of 

Transportation, Docket Operations, 1200 

New Jersey Avenue, SE., West Building 

Ground Floor, Room W12–140, 

Washington, DC 20590–0001. You must 

identify the docket number FAA–2009– 

0858/Airspace Docket No. 09–ASW–22, 

at the beginning of your comments. You 

may also submit comments through the 

Internet at http://www.regulations.gov. 

You may review the public docket 

containing the proposal, any comments 

received, and any final disposition in 

person in the Dockets Office between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. The 

Docket Office (telephone 1–800–647– 

5527), is on the ground floor of the 

building at the above address. 

FOR FURTHER INFORMATION CONTACT: 

Scott Enander, Central Service Center, 

Operations Support Group, Federal 

Aviation Administration, Southwest 

Region, 2601 Meacham Blvd., Fort 

Worth, TX 76137; telephone: (817) 321– 

7716. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

Interested parties are invited to 

participate in this proposed rulemaking 

by submitting such written data, views, 

or arguments, as they may desire. 

Comments that provide the factual basis 

supporting the views and suggestions 

presented are particularly helpful in 

developing reasoned regulatory 

decisions on the proposal. Comments 

are specifically invited on the overall 

regulatory, aeronautical, economic, 

environmental, and energy-related 

aspects of the proposal. 

Communications should identify both 

docket numbers and be submitted in 

triplicate to the address listed above. 

Commenters wishing the FAA to 

acknowledge receipt of their comments 

on this notice must submit with those 

comments a self-addressed, stamped 

postcard on which the following 

statement is made: ‘‘Comments to 

Docket No. FAA–2009–0858/Airspace 

Docket No. 09–ASW–22.’’ The postcard 

will be date/time stamped and returned 

to the commenter. 

Availability of NPRMs 

An electronic copy of this document 

may be downloaded through the 

Internet at http://www.regulations.gov. 

Recently published rulemaking 

documents can also be accessed through 

the FAA’s Web page at http:// 

www.faa.gov/airports_airtraffic/ 

air_traffic/publications/ 

airspace_amendments/. 

Additionally, any person may obtain 

a copy of this notice by submitting a 

request to the Federal Aviation 

Administration (FAA), Office of Air 

Traffic Airspace Management, ATA– 

400, 800 Independence Avenue, SW., 

Washington, DC 20591, or by calling 

(202) 267–8783. Communications must 

identify both docket numbers for this 

notice. Persons interested in being 

placed on a mailing list for future 

NPRMs should contact the FAA’s Office 

of Rulemaking (202) 267–9677, to 

request a copy of Advisory Circular No. 

11–2A, Notice of Proposed Rulemaking 

Distribution System, which describes 

the application procedure. 

The Proposal 

This action proposes to amend Title 

14, Code of Federal Regulations (14 

CFR), part 71 by adding additional Class 

E airspace extending upward from 700 

feet above the surface for SIAPs 

operations at Llano Municipal Airport, 

Llano, TX. This action would also 

update the geographic coordinates of 

Llano Municipal Airport. Controlled 

airspace is needed for the safety and 

management of IFR operations at the 

airport. 

Class E airspace areas are published 

in Paragraph 6005 of FAA Order 

7400.9T, dated August 27, 2009, and 

effective September 15, 2009, which is 

incorporated by reference in 14 CFR 

71.1. The Class E airspace designation 

listed in this document would be 

published subsequently in the Order. 

The FAA has determined that this 

proposed regulation only involves an 

established body of technical 

regulations for which frequent and 

routine amendments are necessary to 

keep them operationally current. It, 

therefore, (1) is not a ‘‘significant 

regulatory action’’ under Executive 

Order 12866; (2) is not a ‘‘significant 

rule’’ under DOT Regulatory Policies 

and Procedures (44 FR 11034; February 

26, 1979); and (3) does not warrant 

preparation of a Regulatory Evaluation 

as the anticipated impact is so minimal. 

Since this is a routine matter that will 

only affect air traffic procedures and air 

navigation, it is certified that this rule, 


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