Document ID: FAA-2006-24281-0088
Agency: faa
Document Type: Rule
Title: Aging Airplane Program: Widespread Fatigue Damage
Posted Date: 2010-11-15T05:00Z

[Federal Register Volume 75, Number 219 (Monday, November 15, 2010)]
[Rules and Regulations]
[Pages 69746-69789]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-28363]

[[Page 69745]]

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Part II

Department of Transportation

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Federal Aviation Administration

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14 CFR Parts 25, 26, 121, et al.

Aging Airplane Program: Widespread Fatigue Damage; Final Rule

  Federal Register / Vol. 75 , No. 219 / Monday, November 15, 2010 / 
Rules and Regulations  

[[Page 69746]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 25, 26, 121, and 129

[Docket No. FAA-2006-24281; Amendment Nos. 25-132, 26-5, 121-351, 129-
48]
RIN 2120-AI05

Aging Airplane Program: Widespread Fatigue Damage

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: This final rule amends FAA regulations pertaining to 
certification and operation of transport category airplanes to prevent 
widespread fatigue damage in those airplanes. For certain existing 
airplanes, the rule requires design approval holders to evaluate their 
airplanes to establish a limit of validity of the engineering data that 
supports the structural maintenance program (LOV). For future 
airplanes, the rule requires all applicants for type certificates, 
after the affective date of the rule, to establish an LOV. Design 
approval holders and applicants must demonstrate that the airplane will 
be free from widespread fatigue damage up to the LOV. The rule requires 
that operators of any affected airplane incorporate the LOV into the 
maintenance program for that airplane. Operators may not fly an 
airplane beyond its LOV unless an extended LOV is approved.

DATES: These amendments become effective January 14, 2011.

FOR FURTHER INFORMATION CONTACT: If you have technical questions 
concerning this rule, contact Walter Sippel, ANM-115, Airframe/Cabin 
Safety Branch, Federal Aviation Administration, 1601 Lind Avenue SW., 
Renton, WA 98057-3356; telephone (425) 227-2774; facsimile (425) 227-
1232; e-mail walter.sippel@faa.gov. If you have legal questions, 
contact Doug Anderson, Office of Regional Counsel, Federal Aviation 
Administration, 1601 Lind Avenue SW., Renton, WA 98057-3356; telephone 
(425) 227-2166; facsimile (425) 227-1007; e-mail 
douglas.anderson@faa.gov.

SUPPLEMENTARY INFORMATION: 

Authority for This Rulemaking

    The FAA's authority to issue rules on aviation safety is found in 
Title 49 of the United States Code. Subtitle I, section 106 describes 
the authority of the FAA Administrator. Subtitle VII-Aviation Programs 
describes in more detail the scope of the agency's authority.
    This rulemaking is promulgated under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, the FAA is charged with promoting 
safe flight of civil aircraft in air commerce by prescribing minimum 
standards required in the interest of safety for the design and 
performance of aircraft; regulations and minimum standards in the 
interest of safety for inspecting, servicing, and overhauling aircraft; 
and regulations for other practices, methods, and procedures the 
administrator finds necessary for safety in air commerce. This 
regulation is within the scope of that authority because it 
prescribes--
     New safety standards for the design of transport category 
airplanes, and
     New requirements necessary for safety for the design, 
production, operation and maintenance of those airplanes and for other 
practices, methods, and procedures relating to those airplanes.

Contents

I. Executive Summary
II. Background
    A. Summary of the NPRM
    B. Related Activities
    C. Differences between NPRM and Final Rule
    1. Substantive changes
    2. Regulatory Evaluation changes
    3. New part 26 for design approval holders' airworthiness 
requirements
    4. New subparts for airworthiness operational rules
    D. Summary of Comments
III. Discussion of the Final Rule
    A. Overview
    1. Widespread fatigue damage
    2. Final rule
    B. Requests for Deferral or Withdrawal of Rule
    1. Safety benefits don't justify rule
    2. Existing programs serve purpose of rule
    3. Divide rule into two
    C. Concept of Operational Limits
    1. Requests for requiring maintenance programs instead
    2. Single retirement point for a model
    3. Potentially adverse effect on safety
    D. Change in Terminology (Initial Operational Limit to LOV)
    1. Rationale for the term LOV
    2. Refer to the structural maintenance program
    E. Repairs, Alterations, and Modifications
    1. Whether repairs, alterations, and modifications pose WFD 
risks
    2. Relationship to damage tolerance requirements (Sec.  25.571)
    a. Pre-Amendment 25-96 airplanes
    b. Airplanes certified to Amendment 25-96 or later
    3. Guidelines for repairs, alterations, and modifications
    4. Rely on the Changed Product Rule
    F. LOVs for Existing Airplanes
    1. NPRM compliance date
    2. When to set LOVs for existing airplanes
    a. Pre-Amendment 25-45 airplanes
    b. Airplanes certified to Amendment 25-45 or later
    3. Varying implementation strategies
    4. FAA review and approval time
    G. LOVs for Future Airplanes: Revisions to Sec.  25.571 and 
Appendix H
    1. Opposition to changes to Sec.  25.571
    2. Change to Appendix H
    3. When to set LOVs for future airplanes
    H. How to Set LOVs
    I. How to Extend LOVs
    1. Change the procedure for extending LOVs
    2. Evaluation of repairs, alterations, and modifications for LOV 
extensions
    3. Alternate means of compliance (AMOCs)
    4. Extension procedure doesn't allow public comment
    J. Applicability for Existing Airplanes
    1. Type certificates issued after January 1, 1958
    2. Original type certification
    3. Airplane configuration
    4. Weight cutoff
    5. Default LOVs and excluded airplanes
    a. Table 1--Default LOVs
    b. Table 2--Airplanes excluded from Sec.  26.21
    6. Bombardier airplanes
    7. Intrastate operations in Alaska
    8. Composite structures
    K. Harmonization
    L. Regulatory Evaluation
    1. Benefits of proposed rule
    2. Costs of proposed rule
    a. Need to know LOVs to determine cost
    b. Need to know maintenance actions to determine cost
    c. Costs to manufacturers
    d. Cost of failing to harmonize rule
    e. Cost to replace an airplane
    f. Residual value of airplanes
    3. ``Rotable'' parts
    4. Use of LOVs for financial evaluations
IV. Regulatory Notices and Analyses

I. Executive Summary

    This final rule requires certain actions to prevent catastrophic 
failure due to widespread fatigue damage (WFD) throughout the 
operational life of certain existing transport category airplanes and 
all those to be certificated in the future. Existing airplanes subject 
to the rule are turbine-powered airplanes with a type certificate 
issued after January 1, 1958, which have a maximum takeoff gross weight 
greater than 75,000 pounds and are operated under part 121 or 129. The 
rule applies to all transport category airplanes to be certificated in 
the future, regardless of maximum takeoff gross weight or how they are 
operated. The benefits of this rule are estimated at a present value of 
$4.8 million. The cost is estimated at a present value of $3.6 million.

[[Page 69747]]

               Figure 1--WFD Final Rule Benefits and Costs
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                                                            7% Present
                                           Nominal value     value ($
                                           ($ millions)      millions)
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Benefits................................             9.8             4.8
Costs...................................             3.8             3.6
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    Fatigue damage to a metallic structure occurs when the structure is 
subjected to repeated loads, such as the pressurization and 
depressurization that occurs with every flight of an airplane. Over 
time this fatigue damage results in cracks in the structure, and the 
cracks may begin to grow together. Widespread fatigue damage is the 
simultaneous presence of fatigue cracks at multiple structural 
locations that are of sufficient size and density that the structure 
will no longer meet the residual strength requirements of Sec.  
25.571(b).\1\ Structural fatigue characteristics of airplanes are 
understood only up to the point where analyses and testing of the 
structure are valid. There is concern about operating an airplane 
beyond that point for several reasons. One reason is that WFD is 
increasingly likely as the airplane ages, and is certain if the 
airplane is operated long enough. Another is that existing inspection 
methods do not reliably detect WFD because cracks are initially so 
small and may then link up and grow so rapidly that the affected 
structure fails before an inspection can be performed to detect the 
cracks.
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    \1\ After sustaining a certain level of damage, the remaining 
structure must be able to withstand certain static loads without 
failure. In the context of WFD, the damage is a result of the 
simultaneous presence of fatigue cracks at multiple locations in the 
same structural element (i.e., multiple site damage) or the 
simultaneous presence of fatigue cracks in similar adjacent 
structural elements (i.e., multiple element damage).
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    To preclude WFD related incidents in existing transport category 
airplanes, this final rule requires holders of design approvals for 
those airplanes subject to the rule to perform the following actions:
    1. Establish a limit of validity of the engineering data that 
supports the structural maintenance program (LOV);
    2. Demonstrate that WFD will not occur in the airplane prior to 
reaching the LOV; and
    3. Establish or revise the Airworthiness Limitations section in the 
Instructions for Continued Airworthiness to include the LOV.
    As used in this preamble, the term ``design approval holders'' 
includes holders of type certificates, supplemental type certificates, 
or amended type certificates, and applicants for such approvals. In the 
context of this final rule, the design approval holder is generally the 
type certificate holder. Requiring design approval holders to perform 
the actions listed above is intended to support compliance by operators 
with today's amendments to parts 121 and 129. This final rule amends 
those parts to require that operators incorporate the LOV as 
airworthiness limitations into their maintenance program for each 
affected model that they operate.
    The amendments to the operating rules have the effect of 
prohibiting operation of an airplane beyond its LOV. However, today's 
rule provides an option for any person to extend the LOV for an 
airplane and to develop the maintenance actions which support the 
extended limit. Thereafter, to operate an airplane beyond the existing 
LOV, an operator must incorporate the extended LOV and associated 
maintenance actions into its maintenance program. The airplane may not 
be operated beyond the extended LOV.
    In response to comments on the notice of proposed rulemaking, the 
FAA has made a number of substantive changes which significantly reduce 
the costs presented in the proposal. The FAA has--
     Eliminated the requirement to evaluate WFD associated with 
most repairs, alterations, and modifications of the baseline \2\ 
airplane structure.
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    \2\ Baseline structure means structure that is designed under 
the original type certificate or amended type certificate for that 
airplane model.
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     Simplified how an LOV may be extended.
     Extended the compliance dates by which design approval 
holders must establish an LOV for existing airplanes.
     Extended the time for operators to incorporate LOVs into 
their maintenance programs.
     Limited the applicability of the final rule to ``transport 
category, turbine-powered airplanes with a type certificate issued 
after January 1, 1958.''
    Today's rule requires that design approval holders take the 
necessary steps to preclude WFD in the future by requiring that they 
establish LOVs. Although the rule allows design approval holders to 
establish LOVs without relying on maintenance actions, the FAA expects 
most current design approval holders to adopt LOVs that will rely on 
such actions. Since WFD is by definition a condition in which structure 
will no longer meet the residual strength requirements of Sec.  
25.571(b), it could lead to a catastrophic failure. Thus the FAA would 
mandate those maintenance actions by airworthiness directive. The 
agency expects these actions to greatly reduce the number of 
unanticipated inspections and repairs resulting from emergency 
airworthiness directives the FAA issues when WFD is discovered in 
service. The FAA estimates the value of managing WFD with maintenance 
actions developed under this final rule versus the current practice of 
issuing airworthiness directives as WFD is found is worth $4.8 million 
in present value. There are other benefits of this rule that were not 
included in the final benefit assessment. They include prevention of 
accidents and a longer economic life for the airplane. The FAA 
estimates that this rule will cause one airplane to be retired because 
of its reaching the anticipated LOV in the 20-year analysis period. The 
retirement of this one airplane will result in costs of approximately 
$3.8 million, with a present value of approximately $3.6 million. This 
operator's cost is the only cost attributed to the final rule, since 
manufacturer costs were found to be minimal.
    Thus, as noted earlier, this final rule's estimated present value 
benefits of $4.8 million exceed the estimated present value costs of 
approximately $3.6 million.

II. Background

A. Summary of the NPRM

    On April 18, 2006, the FAA published a notice of proposed 
rulemaking (NPRM), entitled Aging Aircraft Program: Widespread Fatigue 
Damage.\3\ That proposal was based on a recommendation from the 
Aviation Rulemaking Advisory Committee (ARAC). The NPRM contained 
extensive requirements for setting and supporting an initial 
operational limit for an airplane model. The FAA proposed that the rule 
apply to transport category airplanes with a maximum gross takeoff 
weight of greater than 75,000 pounds. The due date for comments was 
July 17, 2006.
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    \3\ 71 FR 19928
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    The FAA proposed that design approval holders for those airplanes 
be required to take actions to preclude WFD. For new airplanes, the FAA 
proposed to amend Sec.  25.571 and Appendix H to part 25 to require 
that applicants for a new type certificate establish an initial 
operational limit and include that limit in the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness for 
the airplane. The agency also proposed that applicants develop 
guidelines for evaluating repairs, alterations, and modifications for 
WFD.

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    Section 25.1807 proposed that holders of design approvals for 
existing airplanes or applicants for such approvals be required to do 
the following:
    1. Establish an initial operational limit; and
    2. Establish a new Airworthiness Limitations section or revise an 
existing Airworthiness Limitations section to include the initial 
operational limit.
    Section 25.1807(g) proposed that holders of design approvals for 
existing airplanes or applicants for such approvals be required to 
prepare the following:
    1. A list of repairs and modifications developed and documented by 
the design approval holder;
    2. Service information for maintenance actions necessary to 
preclude WFD from occurring before the initial operational limit; and
    3. Guidelines for identifying, evaluating, and preparing service 
information for repairs, alterations, and modifications for which no 
service information exists.
    For existing airplanes for which an initial operational limit is 
established, Sec.  25.1809 proposed that design changes be evaluated 
for susceptibility to WFD and, if a change were susceptible, that the 
design approval holder identify when WFD is likely to occur and whether 
maintenance actions would be required. Section 25.1811 provided that 
any person could apply to extend an operational limit, using a process 
similar to that for establishing the initial operational limit. Under 
Sec.  25.1813, certain repairs, alterations, and modifications proposed 
for installation on airplanes with an extended operational limit would 
also be evaluated.
    The FAA proposed to amend the operating requirements of parts 121 
and 129 to require that no operator could operate an airplane unless 
the initial operational limit or extended operational limit for the 
airplane had been incorporated into the operator's maintenance program.
    The NPRM contains the background and rationale for this rulemaking 
and, except where the FAA has made revisions in this final rule, should 
be referred to for that information.

B. Related Activities

    In July 2004, the FAA published the notice entitled ``Fuel Tank 
Safety Compliance Extension (Final Rule) and Aging Airplane Program 
Update (Request for Comments)'' \4\ to propose airworthiness 
requirements for design approval holders to support certain operational 
rules. The FAA requested comments on the agency's proposal.
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    \4\ 69 FR 45936, July 30, 2004.
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    In July 2005, the FAA published a disposition of comments received 
in response to our request.\5\ Also in July 2005, the agency published 
a policy statement, ``Safety-A Shared Responsibility-New Direction for 
Addressing Airworthiness Issues for Transport Airplanes,'' \6\ that 
explains our reasons for adopting requirements for design approval 
holders.
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    \5\ 70 FR 40168, July 12, 2005: Fuel Tank Safety Compliance 
Extension (final rule) and Aging Airplane Program Update (Request 
for comments).
    \6\ 70 FR 40166, July 12, 2005 (PS-ANM110-7-12-2005).
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    On May 22, 2006, the FAA published a Notice of Availability and 
request for comments on proposed Advisory Circular (AC) 120-YY, 
Widespread Fatigue Damage on Metallic Structure. The notice stated that 
the proposed AC could be found on the Internet at http://www.faa.gov/aircraft/draft_docs. This proposed advisory circular provides guidance 
to design approval holders on establishing initial and extended 
operational limits to preclude WFD for certain transport category 
airplanes and evaluating repairs, alterations, and modifications to the 
airplanes. The advisory circular also provides guidance to operators on 
incorporating the initial or extended operational limit and any related 
airworthiness limitation items into their maintenance programs. The 
notice specified that comments on the proposed advisory circular were 
to be received by July 17, 2006.
    On July 7, 2006, at the request of a number of commenters, the FAA 
published a notice \7\ extending the comment period on both the NPRM 
and proposed AC 120-YY to September 18, 2006. On August 18, 2006, the 
agency posted proposed AC 25.571-1X, Damage Tolerance and Fatigue 
Evaluation of Structure, on the Internet at http://www.faa.gov/aircraft/draft_docs. Comments on this document, which proposed 
revision of existing AC 25.571-1C, were due by October 21, 2006.
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    \7\ 71 FR 38540.
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    On November 26, 2006, the FAA held a public meeting with the ARAC 
Transport Airplane and Engine Issues Group. Under ARAC, the 
Airworthiness Assurance Working Group (AAWG) had previously provided 
recommendations to the FAA on how to address widespread fatigue damage. 
Because the FAA had received several comments concerning differences 
between the AAWG's recommendations and the NPRM, the meeting was held 
to discuss the reasons for these differences. The FAA's presentation at 
the meeting has been placed in the docket for this rulemaking. Except 
as discussed in the context of specific issues affecting this final 
rule, the FAA will not revisit those differences here.
    On December 11, 2008, at the request of the Acting Administrator, 
the FAA held a public meeting to allow comments on the changes that had 
occurred to the rule since it had been proposed in the NPRM. A 
Technical Document describing those changes was posted in the docket, 
and the announcement of the meeting and opening of the comment period 
for the Technical Document was published in the Federal Register on 
Nov. 7, 2008 (73 FR 66205). The public was invited to submit comments 
on the Technical Document either in person at the meeting or by sending 
them to the docket. Seventy-one people attended the meeting and Boeing, 
the Air Transport Association of America (ATA), and FedEx made 
presentations, along with the FAA. Many attendees commented or asked 
questions. In addition, 12 commenters submitted comments about the 
Technical Document to the docket. The comment period closed on December 
22, 2008.
    While some of the comments received during the comment period for 
the Technical Document were new, many were restatements of comments 
made after publication of the NPRM. We address all of the comments, 
from both comment periods, in the section below. Comments received 
during both comment periods are posted to the docket. A transcript of 
the public meeting, including presentations given and comments 
delivered there, may also be found in the docket.

C. Differences Between NPRM and Final Rule

1. Substantive Changes
    The FAA has eliminated the requirement to evaluate WFD associated 
with most repairs, alterations, and modifications of the baseline 
airplane structure.\8\ The agency has also made a change in 
terminology. This final rule uses the term ``limit of validity of the 
engineering data that supports the maintenance program'' (LOV) rather 
than the term ``initial operational limit.'' The FAA finds that the 
term ``limit of validity'' is more appropriate than the term ``initial 
operational limit'' in defining the point to which an airplane

[[Page 69749]]

may be safely operated. The requirements in this final rule for 
establishing the LOV under Sec.  26.21 are that it be supported by test 
evidence and analysis at a minimum and, if available, by service 
experience or service experience and teardown inspection results for 
those airplanes of similar structural design with the highest total 
accumulation of flight cycles or flight hours (commonly referred to as 
high-time airplanes). This criterion is similar to the criterion used 
in Sec.  25.571(b). This final rule also clarifies how the LOV may be 
extended, using the same type of evaluation as that required for 
setting the LOV under Sec.  26.21.
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    \8\ The final rule requires that design approval holders 
evaluate airplane configurations that include modifications mandated 
by airworthiness directive.
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    In response to requests for more time, the FAA has extended the 
compliance dates by which design approval holders must establish an LOV 
for existing airplanes. Those dates vary according to the age of the 
airplanes, from 18 months after the effective date for the oldest 
airplanes to 60 months after the effective date for the newest ones. 
Additionally, the agency has extended the time for operators to 
incorporate LOVs into their maintenance programs. These dates vary with 
the age of the airplanes as well, and are 12 months later than the 
related design approval compliance dates, thus giving operators 12 
months to incorporate the LOV into their maintenance programs. Operator 
compliance dates range from 30 to 72 months after the effective date. 
The FAA has also changed the proposed operational rules to correct an 
inadvertent ambiguity in the NPRM regarding obligations of operators of 
airplanes for which the type certificate holder might fail to establish 
an LOV as required.
    Another change involves applicability to existing transport 
category airplanes. This final rule applies to ``transport category, 
turbine-powered airplanes with a type certificate issued after January 
1, 1958.'' This limitation was added to make applicability of today's 
rule consistent with that of the other aging airplane rules. The FAA 
also added airplanes to the list of those excluded from the LOV 
requirements of Sec.  26.21 because the airplanes are not operated 
under parts 121 or 129. Either they are being operated under different 
parts of the Code of Federal Regulations (CFR) or they are not in 
service at this time. The number of these airplanes still operating is 
very small, and the probability of their retirement in the near future 
is high.
2. Regulatory Evaluation Changes
    The FAA has substantially revised the Regulatory Evaluation for 
several reasons. One concerns differences between the rule as proposed 
and the final rule. For example, the requirement to evaluate WFD 
associated with repairs, alterations, and modifications of the baseline 
airplane structure, except for those mandated by airworthiness 
directives, has been eliminated from this final rule. Another reason 
concerns information received during the rulemaking process which 
indicated that some of the initial assumptions about benefits and costs 
of the rule were not valid. For example, initially, the FAA assumed 
that design approval holders would set the LOV for a specific airplane 
model at the design service goal for that model. However, subsequently, 
some design approval holders indicated that they planned to set the LOV 
33% to 180% higher. The net effect of these changes has been to 
dramatically reduce the costs estimated for compliance with the rule.
    Our revised Regulatory Evaluation lists three potential sources of 
benefits of the rule, namely (1) prevention of accidents; (2) extension 
of the economic life of the airplane with corresponding revenues from 
that additional economic life; and (3) near elimination of emergency 
airworthiness directives.
    Preventing a WFD accident is estimated to have benefits ranging 
from $20 million to $680 million. There are multiple factors, however, 
that make it difficult to forecast that this rule absolutely would 
prevent accidents. Among them are earlier FAA rulemaking actions to 
prevent known fatigue problems from reoccurring.
    Similarly, although specific maintenance actions designed to extend 
the life of airplane structure have added years of service to the DC-9 
fleet, quantification of such values for other models is unnecessary, 
given that benefits already exceed the nearly minimal costs.
    As a result, the quantified benefit of this final rule is based 
solely on the near elimination of emergency ADs pertaining to WFD. The 
analysis assumes the rule will prevent 1.5 days of down time associated 
with emergency ADs.
3. New Part 26 for Design Approval Holders' Airworthiness Requirements
    In the WFD proposed rule, and in proposals for other Aging Airplane 
Program rules, the FAA placed the airworthiness requirements for design 
approval holders in part 25, subpart I. As explained in the Enhanced 
Airworthiness Program for Airplane Systems/Fuel Tank Safety final rule 
(EAPAS/FTS),\9\ the FAA decided after further review and input from 
industry and foreign aviation authorities to place these requirements 
in a new part 26 and move the enabling regulations into part 21.\10\ 
The FAA determined that this was the best course of action because it 
keeps part 25 applicable only to airworthiness standards for transport 
category airplanes. This is important because it maintains 
harmonization and compatibility among the United States, Canada, and 
the European Union regulatory systems. Providing references to part 26 
in part 21 clarifies how the part 26 requirements will address existing 
and future design approvals.
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    \9\ 72 FR 63363, November 8, 2007.
    \10\ Certification Procedures for Products and Parts.
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    In creating part 26, the FAA renumbered the proposed sections of 
part 25, subpart I, and incorporated the changes discussed in this 
preamble. A table of this renumbering is shown below.
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    \11\ This section, which includes an applicability table for 
part 26, was adopted as part of the EAPAS final rule.

                                Figure 2--Table Showing Relationship of Proposed Part 25 Subpart I to Part 26 Final Rule
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                 Part 26 final rule                                                            Proposed part 25
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SUBPART C--Aging Airplane Safety--Widespread         Subpart I--Continued Airworthiness
 Fatigue Damage.
Sec.   26.5 Applicability table....................  New \11\
Sec.   26.21 Limit of validity (LOV)...............  Sec.   25.1807 Initial operational limit: Widespread Fatigue Damage (WFD).
                                                     Sec.   25.1809 Changes to type certificates: Widespread Fatigue Damage (WFD).
Sec.   26.23 Extended limit of validity (LOV)......  Sec.   25.1811 Extended operational limit: Widespread Fatigue Damage (WFD)

[[Page 69750]]

 
                                                     Sec.   25.1813 Repairs, alterations, and modifications: Widespread Fatigue Damage (WFD).
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4. New Subparts for Airworthiness Operational Rules
    The WFD NPRM was among several Aging Airplane Program rulemaking 
initiatives that proposed new subparts (subparts AA and B in parts 121 
and 129, respectively) for airworthiness requirements, and redesignated 
certain sections of parts 121 and 129. Since the EAPAS/FTS final rule 
was the first of these rulemaking initiatives to be codified, the new 
subparts and redesignated sections were adopted in that rule. 
Therefore, the FAA has removed the regulatory language and related 
discussion about these changes from this final rule. This final rule 
adds new sections that include WFD-related requirements: Sec. Sec.  
121.1115 and 129.115.

D. Summary of Comments

    The FAA received comments about the NPRM from 40 commenters, 
including airplane manufacturers, operators, aviation associations, and 
others. The comments covered an array of topics and contained a range 
of responses. There was much support from airplane manufacturers, 
operators, and associations for the concept of precluding WFD in aging 
airplanes. There were also a number of recommendations for changes and 
requests for clarification. As previously discussed, at the December 
11, 2008 public meeting, Boeing, FedEx, and ATA gave presentations of 
their responses to the Technical Document.
    In addition, the FAA received comments about airworthiness 
requirements for design approval holders. We addressed many of the same 
or similar comments in the July 2005 disposition of comments document 
to the Fuel Tank Safety Compliance Extension (Final Rule) and Aging 
Airplane Program Update (Request for Comments). We also explained in 
detail the need for these requirements in our July 2005 policy 
statement. As a result, the FAA will not revisit those comments here.

III. Discussion of the Final Rule

A. Overview

1. Widespread Fatigue Damage
    Widespread fatigue damage is the simultaneous presence of cracks at 
multiple structural locations that are of sufficient size and density 
that the structure will no longer meet the residual strength 
requirements of 14 CFR 25.571(b). This may result in catastrophic 
structural failure and loss of the airplane.
    Fatigue is the gradual deterioration of a material subjected to 
repeated structural loads. When it occurs in more than one location, 
cracks manifest themselves as multiple site damage or multiple element 
damage. Multiple site damage is the simultaneous presence of fatigue 
cracks at multiple locations that grow together in the same structural 
element, such as a large skin panel or lap joint. Multiple element 
damage is the simultaneous presence of fatigue cracks in similar 
adjacent structural elements, such as frames or stringers. Some 
structural elements are susceptible to both types of damage, and both 
types may occur at the same time.
    Cracks associated with multiple site damage and multiple element 
damage are initially so small that they cannot be reliably detected 
with existing inspection methods. Widespread fatigue damage is 
especially hazardous because these small, undetectable cracks in 
metallic structure can ``link up'' and grow very rapidly to bring about 
catastrophic failure of the structure. Although operators perform 
routine structural inspections to detect fatigue damage, fatigue cracks 
related to WFD grow so rapidly that operators cannot inspect 
susceptible structures often enough to detect the cracks before they 
cause structural failure. As a result, many of the findings of these 
types of cracks have been fortuitous: mechanics and others have 
observed fatigue cracks while doing other work. For example, cracks 
have been found by workers while stripping and painting an airplane. 
Cracks have also been found by mechanics conducting unrelated 
inspections of skin anomalies on the external fuselage; further 
investigation revealed multiple cracks in stringers and circumferential 
joints.
    In other cases, undetected multiple site damage in wing or fuselage 
structure has eventually led to catastrophic failure of the structure 
in flight. For example, wing failures have resulted in losses of C-130 
and P4Y-2 airplanes. Failures of aft pressure bulkheads have caused 
decompression of B-747, DC-9, and L-1011 airplanes.
    Concern about WFD was brought to the forefront of public attention 
in April 1988, when an 18-foot-long section of the upper fuselage of a 
Boeing Model 737 airplane separated from the airplane during flight. 
The airplane, operated by Aloha Airlines, was en route from Hilo to 
Honolulu, Hawaii, at 24,000 feet. Onboard were 89 passengers and 6 
crewmembers. A flight attendant died as a result of the accident, and 
eight passengers were injured.
    The damage to the airplane consisted of a total separation and loss 
of a major portion of the upper crown skin and other structure. The 
damaged area extended from the main cabin entrance door aft for about 
18 feet. At the time of the accident, the airplane had accumulated 
89,680 flight cycles and 35,496 flight hours.
    In the years after the Aloha Airlines accident, WFD was discovered 
in the following airplanes:
     Boeing 727: Cracking along a lap joint.
    In 1998, during maintenance, two cracks were found growing out from 
underneath the lap joint. Disassembly of the joint revealed a 20-inch 
hidden crack from multiple site damage on the lower row of rivet holes 
in the inner skin.
     Boeing 737: Cracking along a lap joint.
    In July 2003, a mechanic preparing to paint discovered extensive 
multiple site damage with up to 10 inches of local link-up of cracks in 
one area.
     Boeing 747: Cracking of the aft pressure bulkhead.
    In 2005, Boeing issued service information to address multiple site 
damage of the aft pressure bulkhead radial lap splices. The service 
information was based on analysis and fatigue testing of the aft 
pressure bulkhead.
     Boeing 767: Cracking of the aft pressure bulkhead.
    On November 5, 2003, cracks were found at multiple sites common to 
a single radial lap splice during an inspection of the aft pressure 
bulkhead.
     McDonnell Douglas DC-9: Cracking of the aft pressure 
bulkhead.
    On June 22, 2003, widespread fatigue damage on a DC-9 airplane led 
to rapid decompression at 25,000 feet. Later inspection revealed 
multiple site

[[Page 69751]]

damage with extensive link-up of cracks.
     Lockheed C-130A: Fatigue cracks in the wing structure.
    On August 13, 1994, while responding to a forest fire in the 
Tahachapi Mountains near Pearblossom, California, the airplane 
experienced an in-flight separation of the right wing. All 3 flight 
crewmembers were killed, and the airplane was completely destroyed.
     Lockheed C-130A: Fatigue cracks in the wing structure.
    On June 17, 2002, while executing a fire retardant drop over a 
forest fire near Walker, California, the airplane's wings folded upward 
at the center wing-to-fuselage attachment point, and the airplane broke 
apart. All three flight crewmembers were killed, and the airplane was 
completely destroyed.
     Consolidated-Vultee P4Y-2: Fatigue cracks in the wing 
structure.
    On July 18, 2002, the airplane was maneuvering to deliver fire 
retardant over a forest fire near Estes Park, Colorado, when its left 
wing separated from the airplane. Both flight crewmembers were killed, 
and the airplane was destroyed. An examination of other Consolidated-
Vultee P4Y-2 airplanes revealed that the area was difficult to inspect 
because of its location relative to fuselage structure.
     Lockheed L-1011: Failure in-flight of the aft pressure 
bulkhead stringer attach fittings.
    In August 1995, an L-1011 airplane experienced a rapid 
decompression at 33,000 feet. Twenty stringer end fittings were found 
severed and the aft pressure bulkhead was separated from the fuselage 
crown by a crack approximately 12 feet long. The flight crew was unable 
to maintain cabin pressure control until after rapid descent.
     Boeing 747: Cracking of adjacent fuselage frames.
    In 2005, during an overnight maintenance visit, missing skin 
fasteners common to a fuselage frame were discovered in the upper deck 
area. Further inspection revealed that the frame was severed. 
Substantial cracking was also found in the adjacent left and right 
frames.
     Airbus A300: Cracking of adjacent fuselage frames.
    In 2002, investigations conducted as a result of fatigue cracks 
found on a test article and later in service revealed that cracking of 
certain adjacent fuselage frames could result in multiple element 
damage. The determination was based on analysis, service experience, 
and fatigue testing.
    Since 1988, the FAA has issued approximately 100 airworthiness 
directives to address WFD in airplanes. Approximately 25 percent of 
these airworthiness directives were too urgent to allow the public an 
opportunity to comment in advance. These airworthiness directives 
required inspections, and the FAA later superseded the majority of them 
to expand the inspections or require modifications because inspections 
were not enough to preclude WFD.
    Shortly after the Aloha Airlines accident, the AAWG \12\ was formed 
to identify procedures to ensure continued structural airworthiness of 
aging transport category airplanes. Basic approaches defined by the 
group and accepted by the FAA included recommending procedures to 
preclude WFD in those airplanes. When ARAC was formed in 1991 to 
provide advice and recommendations on safety-related matters to the 
FAA, the AAWG became a working group under its auspices. In 2003 the 
AAWG completed its recommendation on WFD.
---------------------------------------------------------------------------

    \12\ The group was initially known as the Airworthiness 
Assurance Task Force.
---------------------------------------------------------------------------

    In 2004, the FAA tasked ARAC to ``provide a written report on part 
121 and 129 certificate holders operating airplanes with a maximum 
takeoff gross weight of greater than 75,000 pounds to assess the WFD 
characteristics of structural repairs, alterations, and modifications 
as recommended in a previous tasking of the Aviation Rulemaking 
Advisory Committee.'' \13\ During the comment period on the NPRM for 
this final rule, the AAWG was working to complete Task 3, to recommend 
how an operator would include consideration of WFD for repairs, 
alterations, and modifications to airplanes operated under part 121 or 
129.
---------------------------------------------------------------------------

    \13\ Task 3.--Widespread Fatigue Damage (WFD) of Repairs, 
Alterations, and Modifications. Provide a written report providing 
recommendations on how best to enable part 121 and 129 certificate 
holders of airplanes with a maximum gross take-off weight of greater 
than 75,000 pounds to assess the WFD characteristics of structural 
repairs, alterations, and modifications as recommended in a previous 
ARAC tasking. The written report will include a proposed action plan 
to address and/or accomplish these recommendations including actions 
that should be addressed in Task 4 [below]. The report is to be 
submitted to the ARAC, Transport Airplane and Engine Issues Group, 
for approval. The ARAC, Transport Airplane and Engine Issues Group, 
will determine as appropriate the means by which the action plan 
will be implemented. The proposed actions and implementation process 
approved by the ARAC, Transport Airplane and Engine Issues Group, 
will be subject to FAA concurrence. Published in 69 FR 26641, May 
13, 2004.
---------------------------------------------------------------------------

    On April 17, 2007, the AAWG presented its final report on Task 3 to 
ARAC. Many of the conclusions and recommendations in the final report 
are the same as those provided in the comments on the proposed rule 
which are discussed in this preamble.
2. Final Rule
    This final rule requires actions to preclude WFD in transport 
category airplanes. It applies to both existing transport category 
airplanes that have a maximum takeoff gross weight greater than 75,000 
pounds and to all transport category airplanes to be certified in the 
future, regardless of the maximum takeoff weight.
    Today's rule imposes requirements on those holding design approvals 
for existing transport category airplanes that are subject to the rule. 
The design approval holders are required to evaluate the structural 
configuration of each model for which they hold a type certificate to 
determine its susceptibility to WFD and, if it is susceptible, to 
determine that WFD would not occur before the proposed LOV. The 
evaluation would be based on test evidence and analysis at a minimum 
and, if available, service experience or service experience and 
teardown inspection results of airplanes with a high number of total 
accumulated flight cycles or flight hours or both, which are frequently 
referred to as high-time airplanes. The evaluation would be performed 
on airplanes of similar structural design, accounting for differences 
in operating conditions and procedures. Using the results of the 
evaluation, the design approval holder must then establish an LOV.
    Holders of approvals for design changes that increase an airplane's 
maximum takeoff gross weight to more than 75,000 pounds, or decrease it 
from more than 75,000 pounds to 75,000 pounds or less after the 
effective date of the rule, must also evaluate the affected airplanes 
for WFD and establish LOVs for those airplanes.
    The final rule amends Appendix H to part 25 to require that the LOV 
which is established by the design approval holder be included in the 
Airworthiness Limitations section of the Instructions for Continued 
Airworthiness. It also amends operating rules in parts 121 and 129 to 
require that operators of an affected airplane incorporate into their 
maintenance programs an Airworthiness Limitations section that includes 
an LOV for that airplane.
    The amendments to parts 121 and 129 have the effect of prohibiting 
operation of an airplane beyond its LOV.\14\ For

[[Page 69752]]

transport airplane designs developed in the future, the LOV will be 
included in the airplane's airworthiness limitations and will apply 
regardless of how or by whom the airplane is operated. However, the 
final rule allows any person to extend the LOV for an airplane (if the 
person can demonstrate that it will be free of WFD up to the extended 
LOV) and to develop a maintenance program that supports the extended 
limit. Thereafter, the operator must incorporate the extended LOV and 
the associated maintenance actions into the Airworthiness Limitations 
section of its Instructions for Continued Airworthiness and may not 
operate the airplane beyond that limit.
---------------------------------------------------------------------------

    \14\ Under 14 CFR 91.403(c), no person may operate an airplane 
unless applicable airworthiness limitations have been complied with. 
By requiring operators to incorporate the LOV airworthiness 
limitations developed by the design approval holders under this 
rule, this final rule makes those LOVs applicable to the affected 
airplanes, and Sec.  91.403(c) requires operators to comply with 
them.
---------------------------------------------------------------------------

    The remainder of this section of the preamble discusses specific 
comments received.

B. Requests for Deferral or Withdrawal of Rule

    The FAA received a number of comments that rulemaking to preclude 
WFD was not warranted and that the rule, as proposed, should be 
deferred or withdrawn. Commenters included United Parcel Service, 
American Airlines, FedEx, Cargo Airline Association (CAA), National Air 
Carrier Association (NACA), Lynden Air Cargo, ATA, Northwest Airlines, 
Transport Aircraft Technical Services, and Continental Airlines.
1. Safety Benefits Don't Justify Rule
    American Airlines, ATA, and Lynden Air Cargo commented that the 
rule was not justified in terms of safety. They pointed out that there 
has been no catastrophic accident directly attributable to WFD since 
the Aloha Airlines accident in 1988 and that the National 
Transportation Safety Board found that WFD was a contributory factor, 
but not the sole factor, in that accident.
    In contrast, Boeing commented that issuance of this final rule 
would cast a broad safety net on airframe structural performance for 
those types of details the industry has determined may be susceptible 
to WFD. Boeing said this final rule would provide for the establishment 
of safe operational limits and the maintenance actions necessary to 
preclude WFD prior to reaching those limits.
    There have been several instances of major structural failure in 
flight due to fatigue. Therefore the potential for catastrophic 
structural failure is significant. The FAA considers that this 
rulemaking is essential to prevent future accidents or incidents. In 
the past, industry practice for new airplane design certification has 
been to develop some level of understanding of structural fatigue 
characteristics up to the design service goal, but not beyond it. A 
significant number of airplanes being operated currently have already 
accumulated a number of flight cycles or flight hours greater than the 
original design service goal. As the existing fleet continues to age, 
the number of such airplanes will increase. Structural fatigue 
characteristics of airplanes are understood only up to a certain point 
consistent with the analyses performed and the amount of testing 
accomplished. Operation beyond this point without further engineering 
evaluation should not be allowed because, in the absence of 
intervention, the likelihood of WFD increases with the airplane's time 
in service.
2. Existing Programs Serve Purpose of Rule
    United Parcel Service, American Airlines, the CAA, ATA, Transport 
Aircraft Technical Services Company, and Lynden Air Cargo recommended 
that the proposed rule be withdrawn because existing programs serve the 
same purpose as an inspection program for WFD. These commenters were 
referring to existing elements of the Aging Aircraft Program, which 
resulted from the Aloha Airlines accident. They include the following:
     Supplemental Structural Inspection Program,
     Mandatory Modification Program,
     Repair Assessment Program,
     Corrosion Prevention and Control Program.
    In addition, the FAA has issued airworthiness directives to address 
aging airplane safety concerns. Lynden Air Cargo and Transport Aircraft 
Technical Services Company said that the Aloha Airlines accident might 
not have happened if proper accomplishment and FAA oversight of the 
maintenance program had been performed.
    The FAA recognizes that the four elements of the Aging Aircraft 
Program have some inherent ability to detect multiple site damage or 
multiple element damage, but existing inspection methods cannot detect 
such damage reliably. As acknowledged by some of the commenters, these 
four elements were not specifically designed to address WFD; they were 
designed as elements of an overall program to address structural 
degradation on the pre-Amendment 25-45 airplanes over 75,000 pounds 
maximum takeoff gross weight, commonly known as the ``elite eleven.'' 
\15\ This final rule, which specifically addresses WFD, is intended to 
be the last element of the overall Aging Aircraft Program.
---------------------------------------------------------------------------

    \15\ The elite eleven are the original models considered under 
the Aging Aircraft Program. These were airplanes over 75,000 pounds, 
operating under part 121 or 129, that were at a greater risk for 
age-related structural problems because they had high-time airplanes 
that were near or over their design service goals. They include the 
Airbus A300, Boeing 707/720, Boeing 727, certain Boeing 737s, 
certain Boeing 747s, McDonald Douglas DC-8, DC-9/MD-80, and DC-10, 
Lockheed L-1011, Fokker F-28, and the BAC 1-11.
---------------------------------------------------------------------------

    The AAWG, of which several of these commenters were members, 
recognized the inadequacy of existing programs to address WFD when it 
submitted its recommendation for FAA rulemaking on this subject in 
2001. The recommendation included the following discussion:

    Regulatory and industry experts agree that, as the transport 
airplane fleet continues to age, eventually WFD is inevitable. Long-
term reliance on existing maintenance programs, even those that 
incorporate the latest mandatory changes introduced to combat aging, 
creates an unacceptable risk of age-related accidents. Even with the 
existing aging airplane program for large transports in place, WFD 
can and does occur in the fleet. Therefore, the FAA has determined 
that, at a certain point of an airplane's life, the existing aging 
airplane program is not sufficient to ensure the continued 
airworthiness of that fleet of airplanes.

    As discussed previously, the FAA has issued approximately 100 
airworthiness directives to address unsafe conditions due to WFD on a 
number of airplanes. Airworthiness directives are reactive in the sense 
that the agency issues them only after determining that an unsafe 
condition exists in one or more airplanes and is likely to exist or to 
develop in other airplanes of the same type design. Typically, unsafe 
conditions associated with WFD or its precursors have been discovered 
largely by chance by people performing unrelated airplane maintenance.
    The FAA concludes that the agency cannot rely on existing 
programs--including issuing airworthiness directives if the FAA learns 
of an unsafe condition--to detect or address WFD that occurs in aging 
airplanes. These programs do not obviate the need for a rule to prevent 
catastrophic accidents due to WFD. This final rule specifically 
addresses WFD and its precursors by requiring design approval holders 
to evaluate their airplanes for WFD to prevent development of unsafe 
conditions.
    Although maintenance program oversight can always be improved, the

[[Page 69753]]

fact remains that WFD is difficult, if not impossible, to detect. Small 
cracks that can lead to WFD often cannot be detected until they 
suddenly increase in size and ``link up,'' to cause catastrophic 
damage. Dramatic crack growth can occur quite suddenly and quickly, 
after being undetectable for long periods of time. That is why 
maintenance inspections cannot be relied on to detect and repair such 
cracking. Airplane maintenance programs include inspections that are 
designed to detect obvious damage and irregularities. WFD, by its 
nature, is usually hidden, and not readily detectable. Discovery of WFD 
in some airplanes by mechanics has been a purely random occurrence, 
where damage detected was the result of WFD that had progressed to the 
point of failure of structural members. An example is discovery of WFD 
on a Boeing 747, with adjacent frame cracking and separations. It was 
detected because of loose rivets on the skin. Mechanics happened upon 
the WFD damage by chance, because inspections had not uncovered any 
problem. Improving a maintenance program by adding or modifying 
inspections would not necessarily have the effect of improving 
detection of WFD. In general, the only way to address WFD is by 
modifying or replacing structure.
    The National Transportation Safety Board report stated the 
following:

    It is probable that numerous small fatigue cracks in the lap 
joint along S-10L joined to form a large crack (or cracks) similar 
to the crack at S-10L that a passenger saw when boarding the 
accident flight. The damage discovered on the accident airplane, 
damage on other airplanes in the Aloha Airlines fleet, fatigue 
striation growth rates, and the service history of the B-737 lap 
joint disbond problem led the Safety Board to conclude that, at the 
time of the accident, numerous fatigue cracks in the fuselage skin 
lap joint along the S-10L linked up quickly to cause catastrophic 
failure of the large section of the fuselage.

    The AAWG worked on various solutions to the safety problems 
encountered by aging airplanes and was instrumental in developing the 
four programs listed earlier in this document. However, they decided 
that additional actions were needed to preclude WFD in airplanes, and 
the steps they outlined included:
     Setting limits of validity of the maintenance program.
     Deciding whether WFD can be inspected for, and, if so, for 
how long such inspections would be effective.
     Defining when WFD-susceptible structure should be modified 
or replaced.
    Lynden Air Cargo stated that it supported an approach that used 
airworthiness directives to address WFD-susceptible structural 
components instead of an LOV approach for the entire airplane. Lynden 
Air Cargo further stated that the unique design of the L-382G allows 
for the whole airframe to be renewed by replacing WFD-susceptible 
sections (e.g., center wing and outer wing).
    The FAA agrees with Lynden Air Cargo that WFD-susceptible structure 
can be replaced when the engineering data determines it should be 
replaced to preclude WFD. However, as airplanes age, other areas may 
also need to be replaced. The only way to determine that is to evaluate 
the engineering data (analyses, tests, service experience) for the 
entire airplane. Without the LOV, the operational life of an airplane 
is undefined. As a result, the list of areas to inspect, modify, 
replace, or any combination of these may be extensive, since the data 
would need to substantiate an indefinite life.
3. Divide Rule into Two
    FedEx, Northwest Airlines, Continental Airlines, NACA, and ATA 
stated that the proposed draft final rule does not allow the public an 
opportunity to comment on the LOVs that design approval holders propose 
as compliance to part 26. They suggested the rule be divided into two 
rules: one for design approval holders and one for operators. The 
commenters noted that this two-step process would provide the public 
the opportunity to comment on design approval holders' proposed LOVs. 
Deferral of the operator rule would also allow for public comment on 
the WFD maintenance actions at the same time LOVs are established. In 
support of this approach, FedEx specifically argued that the 
incremental costs for the part 26 work to design approval holders is 
minimal, as design approval holders have confirmed in their comments to 
this docket.
    The FAA has determined that complementary, concurrent requirements 
for design approval holders and operators are necessary to achieve the 
safety benefits of the proposed rule in a timely manner. Although 
design approval holders would be required to develop LOVs for affected 
airplanes under part 26, the safety benefit for this rulemaking 
initiative is not met until operators incorporate LOVs and only operate 
airplanes up to the point in time for which it can be shown that the 
airplane will be free from WFD. Until design approval holders actually 
comply with part 26, it's not possible to identify the precise LOV for 
any particular airplane. However, operators have had adequate general 
notice of the objectives of this rulemaking and the proposed methods 
for achieving those objectives in the form of the design approval 
holders' anticipated LOVs. Since the public meeting, both Boeing and 
Airbus have provided revised information about where they anticipate 
those LOVs will be set.
    If additional, multiple rulemakings are necessary to require 
operators to incorporate LOVs into their maintenance programs, there is 
a risk of airplanes exceeding LOVs before those rules become effective. 
The FAA concludes that, to achieve our safety objectives, design 
approval holders and operators must have a shared responsibility on 
certain safety issues affecting the existing fleet. We also conclude, 
from reviews such as the Commercial Airplane Certification Process 
Study (March 2002), that we need to facilitate more effective 
communication of safety information between design approval holders and 
operators. As both technology and airworthiness issues become more 
complex, certain fleet-wide safety issues require the FAA to implement 
complementary requirements for design approval holders and operators, 
when appropriate.

C. Concept of Operational Limits

    This final rule requires design approval holders to establish 
limits of validity of the engineering data that supports the 
maintenance program. The proposed rule would have required that design 
approval holders establish initial operational limits beyond which 
airplanes may not be operated. The initial operational limit would be 
based on the demonstration of freedom from WFD up to that initial 
operational limit.
    Several commenters supported the concept of early detection of WFD 
for aging airplanes but opposed the requirement to establish initial 
operational limits beyond which the airplanes could not be operated. 
These commenters equated establishment of such limits with mandatory 
retirement of airplanes and suggested that, instead, the FAA enhance 
current maintenance programs and practices.
1. Requests for Requiring Maintenance Programs Instead
    An aircraft leasing and trading company named AWAS recommended that 
an inspection-based maintenance program become mandatory as airplanes 
reach their design service goal or their operational limit. Lynden Air 
Cargo stated that there are better, less intrusive

[[Page 69754]]

methods to achieve early detection of WFD than the ``application of 
onerous initial and extended operational limits.'' According to the 
commenter, these methods include proper establishment, accomplishment, 
and enforcement of current airplane maintenance programs, such as the 
maintenance programs required by parts 121 and 135. Lynden Air Cargo 
said it is continuously revising its Continuous Airworthiness 
Maintenance Program to include a design approval holder inspection 
program of Structural Significant Items and recommended structural 
service bulletins.
    These commenters raise some of the same issues as did those who 
opposed the rule altogether. They suggest that current programs for 
aging airplanes or new maintenance programs to detect WFD--along with 
issuance of airworthiness directives when WFD is detected--would 
obviate the need for setting operational limits.
    As stated in the NPRM, the structural fatigue characteristics of 
airplanes are only understood up to a point in time consistent with the 
analyses performed and amount of testing accomplished. Structural 
maintenance programs are designed with this in mind. The LOV is defined 
as the limit of the engineering data that supports the structural 
maintenance program and the current regulatory maintenance requirements 
of parts 121 and 129 do not require that WFD be specifically addressed.
    Also as discussed previously, WFD cannot be detected reliably by 
existing inspection methods. Therefore, the FAA considers that WFD in 
existing airplanes needs to be proactively addressed by requiring 
design approval holders to use relevant engineering data to project the 
number of flight cycles or flight hours or both which the airplanes can 
accumulate without incurring WFD. The engineering data may include the 
evaluation and establishment of maintenance actions that address WFD.
2. Single Retirement Point for a Model
    The Modification and Replacement Parts Association (MARPA) opposed 
a single, mandatory retirement age for airplanes because of the ``vast 
differences possible between aircraft models, missions, and 
maintenance.'' In a similar vein, a company named Safair, which is 
based in South Africa, commented that the difference in structural 
integrity of aging airframes lies in their use and abuse during their 
lives and is largely dependent on the specific load factors to which 
the airframe is subjected. Safair added that the proposed rule may be 
based on inadequate technical evaluation of the actual operational 
experience, considering the number of older aircraft that have been 
safely operated well beyond the actual cycles listed in the proposed 
rule.
    It is true that there may be differences between airplanes of the 
same model which reflect differences in use and maintenance by 
different operators. When manufacturers design an airplane, they 
consider the various ways it may be used, and they develop a ``mission 
profile'' to account for the different loads the airplane may be 
subjected to that must be addressed in their design. In setting the 
LOV, manufacturers will take this information into account, along with 
service experience of the particular airplane model and fatigue test 
evidence. The LOV must apply to an airplane model, because it is based 
on analysis of the service experience of the entire fleet of affected 
airplanes.
3. Potentially Adverse Effect on Safety
    Lynden Air Cargo, MARPA, and the airplane leasing and trading 
company AWAS also suggested that mandatory retirement of airplanes may 
have an adverse effect on safety which has not been considered by the 
FAA. Specifically, AWAS envisioned that operators of airplanes 
approaching their operational limit may perform minimal maintenance on 
airframes to save money. MARPA said that mandatory retirement could 
have a negative influence on the degree and timing of safety-related 
investment, particularly as the aircraft nears its ``throwaway years.'' 
The owner and operator may not intend to be unsafe, suggested MARPA, 
but the question ``Why invest now?'' will arise. A similar comment from 
Lynden Air Cargo anticipated that operators ``are unlikely to apply the 
same level of maintenance effort for an airplane 1,000 flight hours 
from the scrap heap as one with 20,000 flight hours remaining.''
    Under existing operating rules, operators are responsible for 
maintaining their airplanes in an airworthy condition. These 
maintenance requirements apply equally to new and old airplanes. Even 
without this final rule, operators have always planned to retire 
airplanes, and service experience indicates that they generally 
continue to maintain them safely up to that point. The purpose of this 
final rule is to ensure that airplanes are retired before the point 
where they can no longer be safely maintained with respect to WFD.

D. Change in Terminology (Initial Operational Limit to LOV)

1. Rationale for the Term LOV
    The NPRM proposed to establish an initial operational limit, 
expressed in flight cycles, flight hours, or both, beyond which an 
airplane could not be operated. Several commenters, including industry 
representatives on the AAWG and Boeing, objected to this term and 
suggested that instead the FAA refer to the ``limit of validity of the 
engineering data that supports the maintenance program,'' or LOV. This 
final rule uses the term LOV to express the point beyond which an 
airplane cannot be operated (unless an extended LOV has been approved).
    In recommending that the FAA refer to the ``limit of validity of 
the engineering data that supports the maintenance program,'' or LOV, 
industry representatives on the AAWG stated that the term ``initial 
operational limit'' implies that the use of an airplane is limited in 
operation. According to the commenters, the limitation is actually 
based on the engineering knowledge of the structural behavior of the 
airplane model and is intended to ensure that required inspections are 
sufficient to ensure safe operations until a certain number of flight 
cycles or flight hours or both have been reached. The engineering data 
that support such inspection requirements change with time due to 
knowledge gained from in-service experience and additional testing.
    Boeing defined LOV as the point (usually measured in flight cycles) 
in the structural life of an airplane where the engineering basis for 
the maintenance actions contained in the Airworthiness Limitations 
section of the Instructions for Continued Airworthiness is no longer a 
valid predictor of future structural behavior.
    Our intent, as stated in the NPRM, was to ensure that large 
transport category airplanes not be operated beyond their initial 
operational limit, unless operators had incorporated an extended 
operational limit and the service information necessary to support it 
into their maintenance programs. Just as the structural fatigue 
characteristics of airplanes are understood only up to a point 
consistent with analyses performed, testing accomplished, and in-
service experience gained, the engineering data used to develop 
inspections and modifications to preclude WFD is valid only to a 
certain point.
    For these reasons, the FAA finds the term ``limit of validity'' 
more appropriate than the term ``initial operational limit''

[[Page 69755]]

in defining the point to which an airplane may be safely operated in 
relation to WFD. The LOV is substantiated by test evidence and 
analysis. This test evidence and analysis may be augmented by service 
experience, or by service experience and teardown inspection results, 
if available. The service experience and teardown inspection results 
must be for high-time airplanes of similar structural design, 
accounting for differences in operating conditions and procedures. 
Additional engineering data would be necessary to support operation of 
an airplane beyond the LOV. The legal effect of the terms initial 
operational limit and limit of validity is the same. Therefore, this 
final rule uses the term limit of validity instead of the term initial 
operational limit.
2. Refer to the Structural Maintenance Program
    Airbus stated that the term limit of validity of the engineering 
data that supports the maintenance program should be revised for 
clarification. Because WFD is addressed by performing inspections or 
modifications or replacements of airframe structure, the phrase 
``maintenance program'' should be changed to ``structural maintenance 
program.''
    The FAA agrees with Airbus and that change is reflected here.

E. Repairs, Alterations, and Modifications

    This final rule requires design approval holders to establish LOVs 
for airplane models subject to this rule. However, it does not include 
separate requirements to address WFD for repairs, alterations, and 
modifications to those airplanes or to develop guidelines to address 
repairs, alterations, or modifications. The proposed rule would have 
required evaluation of repairs, alterations, and modifications of the 
baseline structure of the airplane. The proposed rule would have also 
required development of guidelines for repairs, alterations, and 
modifications. Persons repairing or altering airplanes certified to 
Sec.  25.571 at Amendment 25-96 or later are already required to show 
the repair or alteration to be free from WFD up to the airplane's 
design service goal. This requirement has not changed since adoption of 
Amendment 25-96 in 1998.\16\
---------------------------------------------------------------------------

    \16\ March 31, 1998, 63 FR 15708.
---------------------------------------------------------------------------

1. Whether Repairs, Alterations, and Modifications Pose WFD Risks
    The Technical Document, discussed earlier, stated that the FAA, in 
response to comments, had removed the proposed requirements for 
repairs, alterations, and modifications. In response to the Technical 
Document, Lynden Air Cargo, Northwest Airlines, ATA, Continental 
Airlines, and FedEx stated that they support removal of requirements 
for repairs, alterations, and modifications from the draft final rule. 
These commenters stated that repairs, alterations, and modifications 
present a reduced risk for WFD because they will be surveyed and 
assessed under the Aging Airplane Safety Final Rule and the Damage 
Tolerance Data for Repairs and Alterations Rule (hereafter referred to 
as the Damage Tolerance Data Rule).\17\ Commenters often used the term 
``Aging Airplane Safety Rule'' to refer to the Damage Tolerance Data 
Rule or the Aging Airplane Safety Final Rule, or both. In instances 
where this occurs, to avoid confusion, the name of the specific rule 
has been inserted in parentheses.
---------------------------------------------------------------------------

    \17\ 72 FR 70486, December 12, 2007.
---------------------------------------------------------------------------

    These commenters expressed the belief that a new WFD requirement 
for repairs, alterations, and modifications is unnecessary because of 
these other requirements, which are already in place. Lynden Air Cargo 
stated that, although it supports removal of requirements to evaluate 
repairs, alterations, and modifications for WFD because the Damage 
Tolerance Data Rule already adequately addresses them, it does not 
understand how each design approval holder is going to establish the 
validity of its maintenance program without validating the repairs and 
alterations it has established under that program. Northwest Airlines 
said that it supported the conclusion of the AAWG that the costs of 
including repairs, alterations, and modifications in the rule 
outweighed the benefits that such a requirement would have.
    Boeing, Airbus, and the European Aviation Safety Agency (EASA) said 
the FAA should reconsider its decision to remove from the rule the 
requirements for evaluating certain repairs, alterations, and 
modifications. All three commenters stated that removing those 
requirements could affect safety because certain alterations could 
affect the LOV and the structural maintenance program that supports the 
LOV. An example of an alteration that could affect the LOV and 
structural maintenance program, the commenter maintained, is one that 
would cause a global loading increase, such as an alteration allowing a 
higher cabin differential pressure. Airbus stated that, although the 
Changed Product Rule (14 CFR 21.101) may address future alterations and 
modifications, it does not cover existing ones.
    Boeing recommended that the FAA revise subpart E of part 26, the 
Damage Tolerance Data Rule, for repairs and alterations, and Sec. Sec.  
121.1109 and 129.109, the Aging Airplane Safety Final Rule, to include 
requirements for evaluating repairs, alterations, and modifications for 
WFD. Boeing's recommendation contains two parts. First, it requests 
that the FAA extend the compliance date for both rules by 18 months 
after the effective date of the WFD rule. Second, it says the FAA 
should incorporate the 2007 ARAC recommendations on evaluating repairs, 
alterations, and modifications into those rules.
    Boeing, Airbus, EASA, and the Allied Pilots Association (APA) 
stated that certain repairs, alterations, and modifications need to be 
evaluated for WFD. APA stated that eliminating the requirement to 
evaluate WFD associated with most repairs, alterations and 
modifications from the final rule is risky, because many high-time 
airplanes fall into this category and will not have any current 
analysis done on their modified airframes.
    In its final report to ARAC concerning Task No. 3, the AAWG stated 
that it has reviewed the accident record and has observed that--while 
there is a technical possibility of a WFD-related accident involving a 
repair or alteration--there are no recorded accidents attributed to WFD 
occurring in properly-installed repairs or alterations. The group added 
that a review of certain repairs, alterations, and modifications is 
necessary, because some of them have the potential to develop WFD.
    The FAA agrees with the commenters that some repairs, alterations, 
and modifications may pose a risk of developing WFD. However, the risk 
appears to be less than that for baseline airplane structure because 
all adverse service experience to date has been limited to baseline 
airplane structure. Type certificate holders design repairs, 
alterations, and modifications using the same design philosophies and 
load cases as for baseline airplane structure. As they do with the 
baseline airplane structure, type certificate holders re-evaluate their 
repairs, alterations, and modifications as service experience is 
gained. Therefore, these repairs, alterations, and modifications should 
be acceptable up to the LOV.
    The repairs, alterations, and modifications developed by persons 
other than type certificate holders may present a slightly greater 
risk, because those persons typically do not have the

[[Page 69756]]

type certificate holder's data or expertise. Although those repairs, 
alterations, and modifications may pose a higher risk for developing 
WFD, there are no recorded accidents attributed to WFD occurring in 
these repairs, alterations, and modifications. Nor have there been a 
significant number of findings of multiple site or element damage 
associated with them.
    The FAA is funding additional research at the agency's Technical 
Center to get a better understanding of these risks and how to address 
them.\18\ This research includes conducting a field survey of repairs, 
alterations, and modifications on high-time airplanes to document the 
existing configurations. The research also includes removing some 
repairs, alterations, and modifications to further evaluate their 
condition. In some cases, testing of particular structure may be 
performed to obtain data for calibration and validation of 
methodologies for predicting WFD. If this research demonstrates that 
additional actions are needed to address risks for repairs, 
alterations, and modifications, the FAA will consider further 
rulemaking.
---------------------------------------------------------------------------

    \18\ Task Area II, Project I, Survey of Transport Airplane 
Structural Repairs and Alterations, Statement of Work 064070723-1, 
dated October 23, 2007; FAA William J. Hughes Technical Center, 
Atlantic City, New Jersey. The Scope of Work for this research is 
available in the docket for this rule.
---------------------------------------------------------------------------

    Based on the above, the FAA has re-evaluated the NPRM and 
determined that the proposed requirements to address repairs, 
alterations, and modifications should be removed from the final rule.
2. Relationship to Damage Tolerance Requirements (Sec.  25.571)
a. Pre-Amendment 25-96 Airplanes
    The FAA received numerous comments requesting that the proposed 
requirements for repairs, alterations, and modifications in the NPRM 
and the related proposed requirements of the Damage Tolerance Data Rule 
NPRM \19\ be combined and aligned in a single rulemaking. These 
commenters included industry representatives who are members of the 
AAWG,\20\ the ATA, Boeing, Airbus, Cessna, and American Airlines. They 
were concerned that separate requirements for repairs, alterations, and 
modifications in the Aging Airplane Safety Rule (the Damage Tolerance 
Data Rule) and the NPRM for this rule would require duplicative 
efforts.
---------------------------------------------------------------------------

    \19\ 71 FR 20574, April 21, 2006.
    \20\ The companies represented are Boeing, Airbus, American 
Airlines, Northwest Airlines, US Airways, United Parcel Service, 
FedEx, ABX (previously known as Airborne Express), Continental 
Airlines, Japan Air Lines, United Airlines, and British Airways. 
Although the comments are not representative of the views of other 
members of the AAWG, including national authorities, for simplicity 
the source of these comments is identified hereafter as ``industry 
representatives on the AAWG.''
---------------------------------------------------------------------------

    Given the proposed timeframes for compliance and the shortage of 
qualified industry resources to perform the required analyses, the 
commenters suggested that separate requirements are unnecessary and 
could not be accomplished within the proposed compliance times. The 
industry representatives on the AAWG stated that there are fewer than 
50 persons in industry who are qualified to perform damage tolerance 
and WFD assessments and most of them are employed by the major design 
approval holders.
    The AAWG stated in its final report on Task 3 that existing 
alterations and repairs would receive a damage tolerance assessment 
under the Aging Airplane Safety Final Rule (developed under the Damage 
Tolerance Data Rule).\21\ The report indicated that this should provide 
an improved level of safety because repairs, alterations, and 
modifications would be surveyed and evaluated. The AAWG recommended 
that repairs not be re-reviewed for WFD if they had already been 
reviewed for damage tolerance.
---------------------------------------------------------------------------

    \21\ The Damage Tolerance Data Rule is Amendment 26-1 and the 
Aging Airplane Safety Final Rule is Amendment 121-337 to the CFR.
---------------------------------------------------------------------------

    Since adoption of Amendment 25-45 in 1978,\22\ the damage tolerance 
provisions of Sec.  25.571 have required consideration of damage at 
multiple sites, the precursor for WFD. While recent efforts on damage 
tolerance have focused on localized cracking, in most cases the design 
approval holders have addressed multiple site damage in their design of 
both baseline structure and of repairs, alterations, and modifications, 
even if indirectly. As a result, the FAA agrees that damage tolerance 
assessment of repairs, alterations, and modifications should provide 
some degree of mitigation of risk, even though the focus of the 
assessments has been on developing inspections, and inspections cannot 
reliably detect WFD.
---------------------------------------------------------------------------

    \22\ October 5, 1978, 43 FR 46238.
---------------------------------------------------------------------------

    The FAA recognizes the scarcity of expert resources in the area of 
damage tolerance and WFD. By removing requirements to address repairs, 
alterations, and modifications from this final rule, the agency is 
allowing those resources to be focused on meeting the compliance dates 
for the Damage Tolerance Data Rule and addressing WFD in baseline 
airplane structure, where the risks are greater. The FAA has recently 
been providing training to its designees and to industry members 
regarding compliance with Sec.  25.571 and the Damage Tolerance Data 
and Aging Airplane Safety Final Rules. In that training, we have 
provided additional guidance on performing a damage-tolerance 
evaluation to assess damage at multiple sites. Adoption of this final 
rule should also result in significant commitments from industry to 
develop resources with this expertise.
b. Airplanes Certified to Amendment 25-96 or Later
    The Technical Document described the agency's intent to remove 
requirements for evaluating repairs, alterations, and modifications for 
WFD. Airbus requested that the FAA clarify that today's final rule will 
not negate those requirements for persons making repairs, alterations, 
or modifications to their airplanes certified to Amendment 25-96. As 
another option, Airbus requested that the WFD rule applicability not 
include Amendment 25-96 or later airplanes, because those airplanes are 
already certified to WFD requirements.
    The FAA agrees that clarification is necessary for airplanes 
certified to Sec.  25.571, Amendment 25-96 or later. Amendment 25-96 
revised Sec.  25.571 to require that full-scale fatigue test evidence 
\23\ be developed to show freedom from WFD up to an airplane model's 
design service goal. Also, any person performing a repair, alteration, 
or modification to those airplanes must address WFD for the repair, 
alteration, or modification, and show compliance with those 
requirements. The newest airplanes, like the Airbus A-380, are 
certified to Amendment 25-96, but most other airplanes operating today 
are certified to an Amendment level prior to 25-96, and thus would not 
be required to comply with those WFD requirements. They would, however, 
be required to comply with the requirements of the Damage Tolerance 
Data Rule.
---------------------------------------------------------------------------

    \23\ Test evidence comprises full fatigue testing up to at least 
two times the proposed design service goal and may include, for 
derivative airplanes, analysis, service experience, or service 
experience and results of tear-down inspections of high-time 
airplanes, if available.
---------------------------------------------------------------------------

    For today's rule, Sec.  25.571 and Appendix H to Part 25 require 
that applicants show an airplane model to be free from WFD up to the 
LOV instead of to the design service goal. Unlike Amendment 25-96, 
which did not require the design service goal to be included in the 
Airworthiness Limitations section, this final rule mandates LOV 
placement in the Airworthiness Limitations section. The

[[Page 69757]]

requirements of today's rule are similar to those of Amendment 25-96. 
Any person who repairs, alters, or modifies any airplane certified 
under today's rule must show that repair, alteration, or modification 
to be free from WFD up to the airplane's LOV.
3. Guidelines for Repairs, Alterations, and Modifications
    Industry representatives on the AAWG and several other commenters 
recommended that proposed Sec.  25.1807(g), along with Sec. Sec.  
25.1809 and 25.1813, be withheld until the working group completed 
relevant taskings from ARAC. In particular, the commenters stated that 
the guidelines in Sec.  25.1807(g)(3) could not be technically 
accomplished because the design approval holders do not have the data 
or knowledge necessary to provide guidance for all possible repair or 
alteration configurations.
    Boeing and Airbus commented that they could support WFD guidelines 
that are limited in scope. The guidelines should identify structure 
prone to development of WFD and provide processes and procedures by 
which operators can access valid data for complying with the rule. But 
these commenters said that such guidelines should not attempt to 
describe methods for determining when WFD is likely to occur or for 
developing service information to preclude WFD. The commenters objected 
to providing guidelines as defined under proposed Sec.  25.1807(g)(3) 
because design approval holders would have no control over how the 
guidelines would be used. They further stated that such guidelines 
could expose design approval holders to potential liability if they are 
applied incorrectly.
    When the FAA issued the NPRM, the agency was relying on the AAWG, 
under an ARAC tasking, to identify a means of compliance that would be 
practical for both design approval holders and operators. Although ARAC 
did not provide detailed recommendations for developing guidelines, it 
did provide a general approach.
    Requirements pertaining to repairs, alterations, and modifications 
were included in the proposed rule to ensure that they would not 
degrade the level of safety provided by the design approval holder's 
compliance with the rule. Although the FAA has removed these proposed 
requirements from the final rule, the agency is engaged with industry 
in a number of activities to address these concerns.
    For repairs, the AAWG recommended in its final report on Task 3 
that each design approval holder update its publications (e.g., 
structural repair manuals, service bulletins, and repair assessment 
guidelines) to include instructions for inspecting and, if necessary, 
modifying structure susceptible to WFD. This update should occur by the 
time the design approval holder has established the LOV for an airplane 
model. The AAWG recommended that design approval holders update their 
service documents for WFD at the same time they are revising these 
documents for the Aging Airplane Safety Rule (the Damage Tolerance Data 
Rule) if the WFD data are available. The FAA expects that design 
approval holders will fulfill this recommendation. To the extent that 
design approval holders update their service documents for WFD, 
operators, when complying with requirements of the Aging Airplane 
Safety Final Rule by using those updated service documents for repairs, 
will be addressing the WFD risks for these repairs. In addition, Sec.  
25.571 already requires consideration of the potential for WFD for 
repairs to airplanes certified to Amendment 25-96 or later.
    For alterations, the AAWG surveyed 642 supplemental type 
certificates. Out of the 642, they identified only 14 alterations and 
modifications that would require assessment for WFD. Based on this, 
they suggested that the FAA review these types of existing alterations 
to determine whether any action is necessary. The Task 3 report did not 
specifically recommend that design approval holders address their 
alterations for WFD. However, recent meetings conducted by certain 
design approval holders indicate that they intend to address their own 
alterations and modifications for WFD in addition to repairs in the 
Task 4 \24\ structures task group activity. The majority of transport 
airplanes operating in the U.S. that are subject to this final rule 
will be addressed by these design approval holders. We anticipate that 
other design approval holders will also review their alterations and 
modifications for WFD.
---------------------------------------------------------------------------

    \24\ Task 4.--Model Specific Programs.
    Oversee the Structural Task Group (STG) activities that will be 
coordinated for each applicable airplane model by the respective 
type certificate holders and part 121 and 129 certificate holders. 
These STG activities will involve the development of model specific 
approaches for compliance with Sec. Sec.  121.370a and 129.16 under 
the guidance material supplied in Task 1. As part of this tasking, 
the AAWG will identify those airplane models that do not have an 
STG, and will assess the need to form one (based on industry 
benefit). For those airplane models that will need to form an STG, 
the AAWG will initiate the coordination required to form the STG 
with the respective type certificate holder and/or part 121 and 129 
certificate holders. In addition, the AAWG will support 
implementation of the action plan to address recommendations made in 
tasks 2 and 3 as determined necessary by the ARAC, Transport 
Airplane and Engine Issues Group, and concurred with by the FAA.
---------------------------------------------------------------------------

    While these activities will not address alterations and 
modifications developed by other persons (including supplemental type 
certificate holders), as stated earlier, the FAA is conducting research 
to get a better understanding of the risks that repairs, alterations, 
and modifications may pose for developing WFD and whether they need to 
be assessed for WFD. If the FAA determines that the risks are 
unacceptable, the FAA will consider further rulemaking to mandate 
assessments.
    This research may also assist in refining means of compliance with 
Sec.  25.571, at Amendment 25-96 or later, for repairs, alterations, 
and modifications. For airplanes certified to Amendment 25-96 or later, 
persons who repair or alter the airplane must address WFD. This has 
typically been done by showing the repair or alteration to be adequate 
up to the airplane's design service goal. With adoption of this final 
rule, repairs, alterations, and modifications to airplanes designed in 
the future will have to be shown to be free from WFD up to the 
airplane's LOV.
4. Rely on the Changed Product Rule
    Northwest Airlines stated that it supports the FAA in removing WFD 
requirements for most repairs, alterations, and modifications, but 
requested that references to future alterations be removed from the 
final rule and addressed by the Changed Product Rule, 14 CFR 21.101. 
The Changed Product Rule requires that significant changes to type-
certificated products comply with the latest amendments of the 
airworthiness standards unless one of the stated exceptions applies. In 
support of its position, Northwest Airlines cited concerns published by 
the AAWG about industry not having the resources or sufficient FAA 
guidance to accomplish WFD analysis for the expected quantities of 
supplemental type certificate alterations.
    Similarly, ATA stated that in view of their coverage under the 
Changed Product Rule, the FAA should exclude future supplemental type 
certificate applications from the applicability of this rule. Northwest 
Airlines and ATA requested that the FAA use the Changed Product Rule to 
regulate which future alterations would need to be evaluated for WFD.
    The Changed Product Rule would require applicants for future 
alterations and modifications to include the latest

[[Page 69758]]

amendment of part 25 for Sec.  25.571 in the certification basis for 
the proposed alteration or modification if the change is considered 
significant. For the purposes of today's rule, applicants would use the 
examples of significant changes identified in AC 21.101-1. For 
transport category airplanes, that AC may be used as a starting point 
for determining whether alterations or modifications are significant 
and must be evaluated to the latest amendment of Sec.  25.571. Examples 
of significant changes from AC 21.101-1 that would be required to be 
assessed for WFD include passenger-to-cargo conversions, gross weight 
increases, and cabin pressure increases. We have revised AC 25.571-1X 
to provide additional guidance for identifying whether a change, or 
structure affected by the change, requires an assessment for WFD. 
Affected structure can be new structure installed by the change or 
existing structure modified by a change. Structure may be affected if 
it is physically changed or if there is a change or redistribution of 
internal loads. The long-term result will be that a changed product 
will have a certification basis that provides a similar level of safety 
to that provided by the certification basis of a new type certificate 
for the same product.

F. Compliance Times for Developing and Implementing LOVs

    For existing airplanes, this final rule uses a phased approach for 
establishing LOVs and divides the compliance dates for holders of 
design approvals and applicable airplane models into three groups. The 
NPRM proposed that design approval holders establish LOVs for all 
affected airplanes by one specific date. The proposed rule did not 
account for the age of airplanes within a model.
    For this final rule, the compliance dates for the different 
airplane groups are identified based on their certification basis 
relative to Sec.  25.571 and are as follows:
     Group I: Pre-Amendment 25-45 airplanes (those with a 
certification basis dating before 1978). The Boeing 727 and the Airbus 
A300 are examples of pre-Amendment 25-45 airplanes.
     Group II: Amendment 25-45 up to but not including 
Amendment 25-96 airplanes (those with a certification basis dating from 
1978 to 1998). This group of airplanes would include the Boeing 757 and 
767 and the Airbus A318.
     Group III: Amendment 25-96 and later airplanes (those with 
a certification basis dating from 1998 to the present). The Airbus A380 
and the Embraer ERJ 170 and 190 are among the airplanes that have this 
certification basis.
    Table 1 in Sec.  26.21 indicates the compliance times for these 
various groups of airplanes. They are 18, 48, and 60 months, 
respectively. These compliance times apply to all existing versions of 
these airplane models.
    For airplane models for which a type certificate is approved as of 
the effective date, but which are not specifically named in Table 1 of 
Sec.  26.21, an LOV must be established within 60 months after the 
effective date of the rule. In Table 1 of Sec.  26.21, those airplanes 
would fall under the category of ``All Other Airplane Models Listed on 
a Type Certificate as of January 14, 2011.''
    For type certificate or amended type certificate approvals that are 
pending as of this final rule's effective date, and for future 
amendments to existing or pending type certificates, this final rule 
requires the applicants to establish an LOV by the latest of the 
following dates:
     Within 60 months after the effective date of the rule,
     The date a certificate is issued, or
     The date specified in the plan approved under Sec.  
25.571(b) indicating when the full-scale fatigue testing and evaluation 
will be complete.
    This final rule requires operators to incorporate the Airworthiness 
Limitations section that includes the LOV into their maintenance 
program within 30, 60, or 72 months after the effective date for Groups 
I, II, and III, respectively. Table 1 in Sec. Sec.  121.1115 and 
129.115 gives the compliance times for operators.
    This final rule also requires operators of affected airplanes whose 
applications for type certificates or amended type certificates are 
pending as of the effective date, or whose application for a type 
certificate or amended type certificate is made after the effective 
date of the rule, to incorporate the Airworthiness Limitations section 
that includes the LOV into their maintenance program at the latest of 
the following compliance times:
     Within 72 months after the effective date of the rule,
     Within 12 months after the LOV is approved, or
     Before operating the airplane.
    In Table 1 of Sec.  121.1115 and Sec.  129.115, those airplanes 
would fall under the category of ``All Other Airplane Models (TCs and 
Amended TCs) not Listed in Table 2.''
    Amended or supplemental type certificates that change the maximum 
takeoff gross weight are grouped separately. Holders of amended type 
certificates or supplemental type certificates that increase the 
maximum takeoff gross weight to greater than 75,000 pounds, regardless 
of whether such change was applied for before or after the effective 
date of the rule, must comply within 18 months after the effective date 
of the rule. Applicants for this type of design change approval whose 
applications are either pending as of the effective date of this final 
rule or submitted after the effective date must comply by the latest of 
the following dates:
     Within 18 months after the effective date of the rule,
     The date the approval is issued, or
     The date specified in the plan approved under Sec.  
25.571(b) indicating when the full-scale fatigue testing and evaluation 
will be complete.
    Applicants for amended type certificates or supplemental type 
certificates applied for after the effective date of the rule that 
decrease the maximum takeoff gross weight to 75,000 pounds or less must 
also comply by the latest of the following dates:
     Within 18 months after the effective date of the rule,
     The date the certificate is issued, or
     The date specified in the plan approved under Sec.  
25.571(b) indicating when the full-scale fatigue testing and evaluation 
will be complete.
    This final rule requires operators of airplanes whose maximum 
takeoff gross weight was decreased to 75,000 pounds or below after the 
effective date of the rule or increased to greater than 75,000 pounds 
at any time by an amended type certificate or supplemental type 
certificate to incorporate the Airworthiness Limitations section that 
includes the LOV into their maintenance program by the latest of the 
following compliance times:
     Within 30 months after the effective date of the rule,
     Within 12 months after the LOV is approved, or
     Before operating the airplane.
    Those airplanes would fall under the category of ``Maximum Takeoff 
Gross Weight Changes'' in Table 1 of Sec.  121.1115 and Sec.  129.115.
    Under 14 CFR 91.403(c), no person may operate an airplane unless 
that person is in compliance with applicable airworthiness limitations. 
By requiring operators to incorporate the Airworthiness Limitations 
Section containing the LOV into the maintenance program, this final 
rule makes those LOVs applicable to the affected airplanes, and Sec.  
91.403(c) requires operators to comply with them.
    Operators of airplanes whose type certificate was pending approval 
as of the effective date of the rule will be required to include one of 
the following

[[Page 69759]]

airworthiness limitations in their maintenance program:
     The LOV that has been specified in the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness; or
     If the LOV has not yet been established, a number equal to 
\1/2\ the number of cycles accumulated on the fatigue test article if a 
type certificate is issued prior to completion of full-scale fatigue 
testing.
    Comments received during the NPRM comment period were responding to 
the one specific compliance date published in the NPRM. Comments 
received during the comment period for the Technical Document, which 
described changes that had occurred to the rule since it had been 
proposed in the NPRM, were in response to the phased compliance dates 
published in the Technical Document, which are the dates cited in 
today's rule.
1. NPRM Compliance Date
    Commenters--including industry representatives on the AAWG, Cessna, 
Continental Airlines, Embraer, AWAS, the CAA, American Airlines, 
Boeing, Airbus, and FedEx--objected to the proposed compliance date of 
December 18, 2007, for both technical and practical reasons. Several 
commenters stated that hard compliance dates and an expected final rule 
issuance in December 2006 would leave design approval holders with less 
than 12 months to comply with the subpart I requirements (now part 26). 
These commenters requested that the FAA revise the compliance dates to 
represent a number of months after the effective date of the rule 
rather than a hard date. This approach would prevent the FAA's schedule 
for issuing the final rule from affecting compliance by design approval 
holders.
    We have revised the compliance dates in this final rule to specify 
that persons must comply either by a date determined as a specified 
number of months after the effective date of the final rule or (for 
applicants) by the date of approval of the related certificate.
2. When to Set LOVs for Existing Airplanes
    Industry representatives on the AAWG, Boeing, Continental Airlines, 
Northwest Airlines, ATA, Lynden Air Cargo, and FedEx stated that there 
should be a phased approach to setting LOVs, with the oldest airplane 
models being addressed first. The industry representatives on the AAWG 
suggested that existing airplane models subject to the rule be divided 
into two groups: (1) Pre-Amendment 25-45 airplanes and (2) airplanes 
certified to Amendment 25-45 or later. The commenters stated that 
performing WFD evaluations on airplane models before the high-time 
airplane reaches its design service goal, as proposed in Sec.  25.1807 
(now Sec.  26.21) and as specified in the Technical Document, would not 
significantly increase operational safety. This is because WFD is 
typically not a concern until later in an airplane's operational life. 
As discussed earlier, these commenters objected to the proposed 
compliance date of December 18, 2007. Commenters also objected to the 
compliance times identified in the Technical Document--that is, 18 
months for pre-Amendment 25-45 airplanes, 48 months for Amendment 25-45 
up to but not including Amendment 25-96 airplanes, and 60 months for 
Amendment 25-96 airplanes.
    Boeing said that the final rule should provide the greatest amount 
of time for design approval holders to develop LOVs, so that LOVs 
provide the greatest flexibility for the fleet. Several commenters 
argued that requiring compliance prior to or concurrent with the Aging 
Airplane Safety Rule (Damage Tolerance Data Rule) would not be 
practical because of limited industry and FAA resources. In addition, 
Boeing and Northwest Airlines argued that establishing an LOV for an 
airplane model before significant service experience had been 
accumulated would result in an erroneous LOV.
    We agree that it makes sense to have compliance dates for 
establishing LOVs for existing airplanes based on the relative safety 
risk (i.e., addressing the oldest airplanes first) and on available 
resources. However, the agency does not agree that ``early'' 
establishment of an LOV will result in an ``erroneous'' LOV. Setting an 
LOV without benefit of significant service experience might result in 
an LOV that sets the limit at a lower number of flight hours or flight 
cycles than one that benefits from significant service experience, but 
it would be incorrect to characterize it as ``erroneous.'' This is 
because the LOV is a function of the fatigue knowledge base available 
at the time it is established.
a. Pre-Amendment 25-45 Airplanes
    Industry representatives on the AAWG, Boeing, Continental Airlines, 
Northwest Airlines, ATA, and FedEx pointed out that the first group of 
airplanes is collectively at the highest risk because of cumulative 
time in service and the limited fatigue test data available for these 
models. They recommended that the compliance date for the first group 
of airplanes should be by a certain date after the effective date of 
the rule. The AAWG's final report \25\ recommends that LOVs be 
established for the first group of airplanes by June 2009, or 18 months 
prior to the operator's compliance date for the final rule, whichever 
occurs later. This would also provide sufficient time for Structures 
Task Groups \26\ including operators of affected airplanes, to 
participate in establishing the LOVs. A later Boeing comment, however, 
requested that the compliance dates for those airplanes be 36 months, 
instead of 18 months (as stated in the technical document), from the 
effective date of the rule. Boeing stated that this additional time 
would allow them to have the FAA review and accept the Boeing 
proprietary LOV methodology, prepare LOV fleet proposals, and 
coordinate them within Boeing and with operators before submitting them 
to the FAA for review and approval.
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    \25\ Aviation Rulemaking Advisory Committee; Transport Airplane 
and Engine Issues--New Task, dated April 11, 2007.
    \26\ A Structures Task Group is a model-specific group that 
consists of type certificate holders and operators responsible for 
the development of aging airplane model-specific programs. It also 
includes regulatory authorities which approve and monitor those 
programs.
---------------------------------------------------------------------------

    The FAA agrees that pre-Amendment 25-45 airplanes should be 
addressed first because they are among the oldest airplanes and at the 
highest risk for developing WFD. In fact, most high-time pre-Amendment 
25-45 airplanes have exceeded their design service goals. While the FAA 
understands that LOVs have been developed for a number of affected 
airplanes, the agency also understands that not all design approval 
holders have begun or completed this activity on all affected models. 
The FAA recognizes the benefits of allowing Structures Task Groups to 
participate in setting LOVs. Therefore, the FAA has determined that the 
compliance period for the oldest affected airplanes should be increased 
to 18 months to allow sufficient time for design approval holders to 
show compliance with today's rule. This increases by six months the 
amount of time design approval holders have to comply over what was 
anticipated in the NPRM. The 2007 AAWG Task 3 Report further supports 
the compliance date of 18 months. In its report, the AAWG stated that 
most of the work for the pre-Amendment 25-45 airplanes has already been 
completed. As a result, we do not concur with the commenter that 36 
months is necessary to establish LOVs.

[[Page 69760]]

b. Airplanes Certified to Amendment 25-45 or Later
    For the second group of airplanes (certified to Amendment 25-45 or 
later), industry representatives on the AAWG, Boeing, Continental 
Airlines, Northwest Airlines, ATA, and FedEx recommended setting a 
compliance date for design approval holders to establish LOVs that are 
tied to both the design service goal and the cumulative time on the 
high-time airplanes of that model. Specifically, the industry 
representatives on the AAWG proposed that within 180 days of the 
effective date of the rule, the type certificate holders provide design 
service goals for all affected airplane models to the FAA for approval. 
Once approved, these design service goals would be placed in an 
appropriate certification document. Other commenters--including Cessna, 
Continental Airlines, Embraer, AWAS, the CAA, American Airlines, 
Boeing, Airbus, and FedEx--agreed with industry representatives on the 
AAWG that the compliance date for setting LOVs should take into account 
both the design service goal and the cumulative time on the high-time 
airplanes of that model.
    The industry representatives on the AAWG proposed that the design 
approval holder prepare a compliance plan with a binding schedule for a 
WFD evaluation when the high-time airplane reaches a point five years 
from its design service goal. The AAWG industry representatives 
suggested that a means of determining this time should be included in 
AC 120-YY. FedEx and Lynden Air Cargo suggested that the FAA use the 
design service goals that are being developed under the Damage 
Tolerance Data Rule to establish compliance dates for establishing LOVs 
and associated WFD maintenance actions. The commenters said that if no 
design service goal or design service objective exists, the LOV should 
be established when the high-time airplane of a particular model 
reaches 20 years of age.
    In contrast, United Parcel Service and Technical Data Analysis, 
Inc. supported establishing LOVs for all affected airplane models as 
soon as possible, because of the uncertainty associated with estimating 
future operating costs and the length of time that airplanes can be 
operated.
    The WFD risk for these newer airplane models is lower than for the 
pre-Amendment 25-45 airplanes because these airplanes are generally 
younger and have been certified to damage tolerance requirements. 
Therefore, the FAA agrees with the industry representatives on the AAWG 
and other commenters that the compliance times can be longer for these 
airplanes. On the other hand, the proposal of the AAWG industry 
representatives would add a level of complexity and uncertainty to 
determining compliance times that the FAA considers unnecessary and 
inappropriate and that would make operators' long-term planning 
difficult.
    Therefore, as discussed earlier, to accommodate the need for a 
longer compliance time for these airplanes, this final rule creates 
three groups of airplane models for determining compliance dates.
     Group I--Pre-Amendment 25-45 (1978) airplanes.
     Group II--Airplanes certified to the requirements of Sec.  
25.571, Amendment 25-45, up to but not including Amendment 25-96 
(1998).
     Group III--Airplanes certified to requirements of Sec.  
25.571, Amendment 25-96 or later.
    Group II airplane models were all subjected to full-scale fatigue 
test programs. In addition, all the models in this group have been in 
service for a period of time. There should, therefore, be a reasonable 
knowledge base readily available on which to base an LOV. Today's rule 
requires establishment of an LOV for all these models within 48 months 
of the effective date of the rule, as indicated in Table 1 of Sec.  
26.21. This would allow design approval holders to schedule development 
of these LOVs after the more urgent development of LOVs for pre-
Amendment 25-45 airplanes, so project schedules would not conflict. At 
the same time, this compliance time would ensure that LOVs are 
established long before the high-time airplanes of these models would 
reach their anticipated LOVs.
    Design approval holders of those models in Group III have had to 
demonstrate or will have to demonstrate with sufficient full-scale test 
evidence that WFD will not occur within the design service goal of the 
airplane. Therefore, the design service goal would be a valid LOV that 
is based on the knowledge base considered. However, because these 
airplanes have not accumulated much time in service, there is less 
urgency in establishing an LOV. As a result, the final rule provides 60 
months after the effective date of the rule to establish an LOV for 
these models. (See Table 1 of Sec.  26.21.) This provides time to re-
evaluate the fatigue data and to establish an LOV which may exceed the 
design service goal. Extending the compliance date for Group III 
airplanes beyond the compliance date for Group II airplanes reduces the 
resource concerns about developing LOVs for multiple airplane models at 
the same time.
    Table 1 of Sec.  26.21 includes a compliance date for airplanes 
that do not appear in the table but may have had a type certificate 
approved by the effective date. These have a compliance period of 60 
months. Some type certificates are pending and may be approved shortly. 
This last row of the table is meant to capture any additional airplanes 
that fit the applicability criteria of Sec.  26.21(a).
    Table 1 of Sec.  26.21 is used to call out existing airplanes and 
assign compliance dates. Holders of type certificates for these models 
must comply with Sec.  26.21(c)(1). The remainder of Sec.  26.21(c) 
specifies additional people who must comply.
    Under today's rule, the compliance times specified in Sec.  
26.21(c) for when applicants must establish an LOV include the date 
specified in the applicant's plan for completion of the full-scale 
fatigue testing and analyses of the testing to demonstrate compliance 
with Sec.  25.571(b).\27\ All applicants who must comply with Sec.  
26.21 may use this date as one option for compliance.
---------------------------------------------------------------------------

    \27\ Under Sec.  21.17, these applicants are subject to Sec.  
25.571 at Amendment 25-96. In addition to this certification basis, 
they are subject to the requirements of this final rule.
---------------------------------------------------------------------------

    Applicants who have the same compliance times and the option to use 
the date specified in the Sec.  25.571(b) plan are:
     Applicants for type certificates for which the application 
is pending as of the effective date.
     Applicants for amendments to type certificates (with the 
exception of those that change the weight of the airplane).
    All of these applicants are required to establish LOVs at the 
latest of the following dates:
     The date the type certificate or amended type certificate 
is issued,
     Within 60 months after the effective date of the rule, or
     The date specified in the plan approved under Sec.  
25.571(b) indicating when the full-scale fatigue testing and evaluation 
will be complete.
    Among these applicants, WFD is of less immediate concern because 
their high-time airplanes will have accumulated relatively few flight 
cycles or flight hours by the compliance date. Establishing LOVs early 
in the service life of these airplanes will assist operators in their 
long-term planning. This approach also serves as a transition to Sec.  
25.571 as amended by this final rule, which requires establishing LOVs 
as part of initial type certification.

[[Page 69761]]

    Maximum takeoff gross weight changes to an airplane are treated 
separately in this rule. Holders of either supplemental type 
certificates or amendments to type certificates that increase maximum 
takeoff gross weights from 75,000 pounds or less to greater than 75,000 
pounds must comply no later than 18 months after the effective date.
    Applicants for supplemental type certificates or amended type 
certificates that increase the maximum takeoff gross weight to greater 
than 75,000 pounds must comply by the latest of the following:
     Within 18 months after the effective date of the rule,
     The date the certificate is issued, or
     The date specified in the plan approved under Sec.  
25.571(b) indicating when the full-scale fatigue testing and evaluation 
will be complete.
    The option of 18 months after the effective date as a compliance 
choice for this group represents a six-month increase in the time to 
comply over what was originally proposed. We based these compliance 
dates on the length of time given for design approval holders of Group 
I airplanes to comply.
    The NPRM did not specify a compliance time for applicants for 
design change approvals that, after the effective date of the rule, 
decrease the maximum takeoff gross weight to 75,000 pounds or less. 
This is because the applicability provision in the NPRM included 
airplanes with maximum takeoff gross weights exceeding 75,000 pounds, 
as approved during the original type certification. By referencing the 
capacity resulting from original type certification, the NPRM required 
applicants to establish LOVs for design change approvals that, after 
the effective date of the rule, decrease the maximum takeoff gross 
weight to 75,000 pounds or less. Although not explicitly stated in the 
NPRM, the LOV for those airplanes is required to be established by the 
compliance date for the original type certification or, in the case of 
applicants, by the date the approval of the design change has been 
issued. Because the NPRM was not clear about when those applicants must 
comply, the FAA has revised today's rule. Applicants for design change 
approvals that decrease the maximum takeoff gross weight to 75,000 
pounds or less after the effective date of the rule must comply within 
18 months after the effective date of the rule or by the date the 
certificate is issued or by the date specified in the plan approved 
under Sec.  25.571(b), whichever occurs latest.
    The FAA has also revised the compliance times to require those 
applicants who would decrease the gross weight of their airplanes after 
the effective date of the rule to submit a compliance plan within 90 
days after the date of application.
3. Varying Implementation Strategies
    APA suggested a way to address concerns about the time needed to 
develop an LOV. The commenter stated that the initial LOVs under 
consideration, as defined in the Technical Document, appear to be 
extremely liberal and based on limited data and minimal analysis. APA 
assumed that manufacturers would need more time to develop their 
analysis procedures, and said that a better approach for establishing 
the initial LOV would be to increase the design service goal by 10% to 
15% and mandate inspections of high-time airplanes that are over their 
design service goal. APA based its suggestion on an assumption that the 
design service goals were based on hard test and engineering data. The 
commenter suggested halving the interval between maintenance checks for 
airplanes over their design service goal. Then, the commenter 
suggested, results of these inspections could be given to the 
manufacturer for use in substantiating the engineering WFD analysis. 
This data could be used to validate future incremental LOV increases.
    Although this commenter maintained that design service goals are 
based on hard test and engineering data, that has not always been the 
criteria by which design service goals have been set. Amendment 25-96 
to Sec.  25.571 introduced requirements that applicants show freedom 
from WFD up to the design service goal. Prior to Amendment 25-96, 
however, there was no requirement for setting a design approval 
holder's design service goal or for validating it. Design approval 
holders have always used engineering data to substantiate their 
designs. Most design approval holders set design service goals for 
their airplanes, even though they were not required to do so. But since 
there were no requirements prior to Amendment 25-96 about what criteria 
must be used to set the design service goal, they have often been set 
for purposes driven more by sales and marketing than by engineering 
data.
    Some design approval holders have stated that LOVs may be 
established at a point anywhere from 33% to 180% higher than the 
airplane's design service goal for certain models. This is because, for 
those design approval holders, there is a large body of in-service data 
to support these higher LOVs. Other design approval holders have taken 
an approach similar to APA's recommendation, in that they have been 
incrementally increasing their airplane model's LOV as the data 
supports it. Today's rule allows for an implementation strategy that 
provides flexibility to design approval holders in determining the 
timing of service information development (with FAA approval), while 
providing operators with certainty regarding the LOV applicable to 
their airplanes. However, no matter how the design approval holder 
chooses to manage LOV development, those LOVs must still be 
substantiated by engineering data.
4. FAA Review and Approval Time
    Industry representatives on the AAWG, Boeing, Airbus, and CAA 
requested that the rule include required time periods for FAA review 
and approval activities. These commenters noted that the rules do not 
currently limit the amount of time the FAA will take to review and 
approve documents and that this will negatively affect their compliance 
time. Several commenters also noted that the amount of time the FAA 
will take to review and approve design approval holders' LOVs could 
reduce operator compliance time significantly.
    We are not including required time periods for FAA review and 
approval of the required compliance activities. Instead, expectations 
for FAA personnel have been defined in FAA Order 8110.104, which 
directs the Aircraft Certification and Flight Standards Services in 
their roles and responsibilities for implementing these initiatives. 
The order includes expected times (6 weeks) for reviewing and approving 
design approval holder compliance plans, plans to correct deficiencies, 
and draft and final compliance data and documents. To facilitate 
implementation, the FAA will train affected personnel in their roles 
and responsibilities and provide in-depth familiarization with 
requirements of the regulations and associated guidance. Ultimately, 
however, the timing of FAA approvals will be determined by the quality 
of the design approval holder submissions and their responsiveness to 
issues raised by the FAA.
    We have structured the requirements of the design approval holder 
rule and developed complementary guidance to facilitate timely review 
and approval of design approval holder submittals (such as compliance 
plans). An increase in operator compliance time would help ensure that 
operators are not affected by the FAA review and approval process. We 
have revised the WFD compliance

[[Page 69762]]

date for operators from 6 months to 12 months after the relevant design 
approval holder compliance date. This date is measured after the 
effective date of the final rule. As previously noted, for Group I, II, 
and III airplanes, the operator compliance dates are 30, 60, and 72 
months, respectively, after the effective date of the rule.

G. LOVs for Future Airplanes: Sec.  25.571, Appendix H, and Operational 
Rules

    This final rule revises Sec.  25.571 to require that--
     An LOV be established that corresponds to the time during 
which it is demonstrated that WFD will not occur in the airplane 
structure, and
     The LOV be included in the Airworthiness Limitations 
section of the Instructions for Continued Airworthiness required by 
Sec.  25.1529.
    Except for the change in terminology from initial operational limit 
to LOV, these revisions to Sec.  25.571 are as proposed in the NPRM.
    For operators of airplanes type certificated in the future, this 
final rule relies on existing operational rules to require operators to 
include the airplane's LOV, which is established under Sec.  25.571 of 
today's rule, into their maintenance/inspection programs. This 
requirement is the same as that which was proposed in the NPRM.
1. Opposition to Changes to Sec.  25.571
    Industry representatives on the AAWG and Airbus commented that no 
change is needed to Sec.  25.571 because airplanes certified to 
Amendment 25-96 must be free from WFD until they reach the design 
service goal, and the design service goal must be declared in the 
appropriate certification document.
    We recognize that Sec.  25.571 at Amendment 25-96 requires full-
scale fatigue test evidence to demonstrate freedom from WFD up to the 
design service goal. However, the current regulations do not require 
that the Airworthiness Limitations section include the design service 
goal as an airworthiness limitation, so operators would be permitted to 
operate airplanes beyond this goal indefinitely. Therefore, the FAA 
finds it necessary to revise Sec.  25.571, as proposed, to require that 
full-scale fatigue test evidence be used to demonstrate freedom from 
WFD up to the LOV and that the LOV be included in the Airworthiness 
Limitations section. These changes are consistent with recommendations 
made in 2003 by the General Structures Harmonization Working Group, a 
separate working group within ARAC.
2. Change to Appendix H
    Under Sec.  25.571, the FAA may issue a type certificate for an 
airplane model prior to completion of full-scale fatigue testing. As 
stated in the NPRM, the FAA did not propose to change this provision 
because the FAA intends that operators be able to operate these 
airplanes while the design approval holder is performing fatigue 
testing. Today's rule retains the requirement of Sec.  25.571 that--if 
a type certificate is issued prior to completion of full-scale fatigue 
testing--the Airworthiness Limitations section must include a number 
equal to [frac12] the number of cycles accumulated on the fatigue test 
article. As additional cycles on the test article are accumulated, the 
number may be adjusted accordingly. This number is an airworthiness 
limitation, and no airplane may be operated beyond it until the fatigue 
testing is completed and the LOV is established.
    For consistency however, the FAA has revised paragraph (a)(4) of 
H25.4 to part 25 (Appendix H) to include a reference to the limitation 
that an airplane may accumulate a number of cycles not greater than \1/
2\ the number of cycles accumulated on the fatigue test article until 
such testing is completed.
3. When to Set LOVs for Future Airplanes
    Industry representatives on the AAWG, Boeing, and American Airlines 
commented that design approval holders should not be required to 
establish an LOV for a future airplane until the high-time airplane 
approaches its design service goal. United Parcel Service, on the other 
hand, recommended that the initial LOV be established during the 
initial certification process, and before the first airplane enters 
service. The ATA recommended that LOVs should be estimated at the time 
of airplane certification but should be reassessed when the high-time 
airplane approaches 75% of the estimate.
    The LOV is a function of the fatigue knowledge base available at 
the time it is established. There should be sufficient data to 
establish an LOV for a new airplane model being certificated once full-
scale fatigue test evidence is completed and assessed, normally several 
years after the airplane enters service. We agree that an LOV 
established for a new airplane model could be reassessed later when 
service information could be used with other data necessary to extend 
the LOV. Eliminating the requirement to address repairs, alterations, 
and modifications will simplify the process for extending the LOV.
    The FAA does not agree that establishment of an LOV for a future 
airplane model should wait until the high-time airplane approaches its 
design service goal. As discussed previously, establishing design 
approval holder compliance dates that are a function of when high-time 
airplanes reach their design service goal would introduce a level of 
complexity and uncertainty to the requirements of the operational rules 
that is unnecessary and inappropriate.
    One manufacturer is already employing the concept of establishing 
LOVs based on the fatigue knowledge base available through the 
certification process. Airbus has already included an LOV in the 
applicable Airworthiness Limitations section approved by EASA for all 
of its models with the exception of the A340.
4. Operational Rules
    For airplanes whose type certificate application is made after the 
effective date of this final rule, LOVs must be established by the date 
the certificate is issued or the date specified in the plan approved 
under Sec.  25.571(b). The LOV will be included in the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness and 
will apply regardless of how or by whom the airplane is operated.
    As discussed above, the FAA may issue a type certificate for an 
airplane model before full-scale fatigue testing has been completed. In 
that case, the Airworthiness Limitations section of the Instructions 
for Continued Airworthiness must include a number equal to \1/2\ the 
number of cycles accumulated on the fatigue test article. Under Sec.  
91.403(c), operators may not operate these airplanes beyond this number 
of cycles. Once the fatigue testing is completed and the LOV is 
established and approved, operators may revise this airworthiness 
limitation to include the LOV. This LOV will be higher than the 
airworthiness limitation specifying \1/2\ the number of fatigue test 
article cycles.

H. How to Set LOVs

    Section 26.21(b) of this final rule requires design approval 
holders to establish an LOV of the engineering data that supports the 
structural maintenance program. This LOV corresponds to the period of 
time, stated as a number of total accumulated flight cycles or flight 
hours, or both, during which the design approval holder is able to 
demonstrate that WFD will not occur in the airplane. This demonstration 
must include an

[[Page 69763]]

evaluation of airplane structural configurations and be supported by 
test evidence and analysis. If available, service experience, or 
service experience and teardown inspection results, may be added to the 
test evidence and analysis to provide additional substantiation. The 
service experience and teardown inspections must be of high-time 
airplanes of similar structural design, accounting for differences in 
operating conditions and procedures.
    The NPRM proposed in Sec.  25.1807(b) [adopted here as Sec.  
26.21(b)] that holders of design approvals for existing airplanes 
subject to the rule be required to evaluate airplane structural 
configurations to determine when WFD was likely to occur for structure 
susceptible to multiple site damage or multiple element damage. The 
results of the evaluation were to be used to support establishment of 
an initial operational limit (now the LOV.)
    The Boeing Company and industry representatives on the AAWG 
commented that proposed Sec.  25.1807 would require an ``evaluation'' 
that is not adequately defined and that there are no objective criteria 
for establishment of an LOV. These deficiencies could result in 
establishment of an LOV based solely on analyses of structure 
susceptible to multiple site damage and multiple element damage, 
without consideration of more relevant and reliable data, such as test 
evidence and service experience. These commenters concluded that, in 
these circumstances, airplanes could be operated well past the point to 
which the engineering data supports safe operation.
    The commenters recommended that the required evaluation explicitly 
include the following tasks, which are described in the AAWG's 2003 
report \28\ as necessary to establish or extend an LOV.
---------------------------------------------------------------------------

    \28\ AAWG, Widespread Fatigue Damage Bridge Tasking Report, July 
23, 2003.
---------------------------------------------------------------------------

    1. Ensure that the basics of the Aging Aircraft Program are in 
existence.
    2. Collect data necessary to extend fatigue test evidence.
    3. Perform analysis of the structure for multiple site damage and 
multiple element damage.
    4. Create and update maintenance documents to include maintenance 
actions and modifications for those areas where it has been predicted 
that multiple site damage and multiple element damage will occur before 
the proposed LOV.
    In addition, industry representatives on the AAWG and Boeing 
recommended that the rule explicitly use the term ``fatigue test 
evidence'' to refer to the collective body of information that should 
be considered in establishing an LOV. The FAA agrees that the first 
task, having basics of the four elements of the Aging Aircraft Program 
in place,\29\ is an important element for continued safe operation out 
to LOV. However, as discussed in the NPRM, this final rule does not 
include requirements related to those initiatives because they are 
already mandated by airworthiness directives, operational rules, and 
airworthiness limitations.
---------------------------------------------------------------------------

    \29\ Mandatory modification, corrosion prevention and control, 
supplemental structural inspection, and repair assessment.
---------------------------------------------------------------------------

    The FAA considers that tasks 2 and 3 are implicit in the text of 
the proposed rule but agrees that proposed Sec.  25.1807 could be 
misinterpreted and result in too much reliance on results of analysis 
to preclude WFD up to the LOV. This was not our intent. In fact, as 
discussed in the NPRM, our intent was consistent with the AAWG's 
recommendations regarding WFD.
    In response to these commenters, the FAA has revised the proposed 
rule to clarify how the LOV is to be established. This final rule 
specifies that--for an LOV to be acceptable--the supporting evaluation 
must demonstrate that the fatigue characteristics and any specified 
maintenance actions for the airplane are sufficient to prevent WFD from 
occurring before the LOV.
    The required demonstration typically involves an evaluation of the 
airplane structure to determine its susceptibility to WFD and, if the 
structure is susceptible, an evaluation indicating that WFD will not 
occur before the proposed LOV. The evaluation must be supported by test 
evidence and analysis. The design approval holder may augment the test 
evidence and analysis with any available service experience, or service 
experience and teardown inspection results of high-time airplanes. 
Service experience and teardown inspection results must be of airplanes 
of similar structural design and must account for differences in 
operating conditions and procedures. After seeing these changes to the 
rule as they were described in the Technical Document, Boeing stated 
that it supports the FAA's adoption of an airplane-level assessment of 
fatigue test evidence as the basis for both the determination and 
extension of LOV.
    The FAA is using the term ``test evidence'' to align with the rule 
text of Sec.  25.571 relative to WFD. Therefore, in the context of this 
final rule, test evidence is data derived from full-scale fatigue 
testing, which may be of the complete airplane, or of separate major 
sections of the airplane, or a combination of the two. The test 
evidence would be used to support the proposed LOV for an airplane 
model. The amount of test evidence required to show compliance would 
depend on where a design approval holder proposes to set an LOV and 
what data (such as test evidence or service experience) already exist.
    For a new airplane model that is pending approval, there should be 
test evidence to address all WFD-susceptible structural areas of an 
airplane. The test duration should be at least two times the proposed 
LOV. The test evidence may be from prior full-scale fatigue tests 
performed by the applicant or others on similar structure. For 
derivative models, the applicant should compare the derivative model to 
the tested model. To use the test evidence from the original 
certification project or previous derivatives, the applicant should 
show that the derivative model does not significantly change the basic 
structural design concept, aerodynamic contour, and internal load 
distribution. Advisory Circulars 120-YY and 25.571-1X further describe 
considerations for when existing test evidence could be used.
    For some older airplanes, fatigue test data may be limited to 
fuselage structure. This is because the pressurized fuselage has been 
considered to be the most fatigue-critical part of the airplane. The 
wing and empennage have typically been considered less critical and, as 
a result, relevant test data may not exist. However, for these same 
airplane models, significant service experience does exist. The FAA 
would accept a combination of test evidence and analysis as well as 
service experience as data to show compliance with this final rule.
    For example, in the case of one of the pre-Amendment 25-45 airplane 
models, significant numbers of airplanes both in service and in storage 
have accumulated flight cycles in excess of the design service goal. 
For this model, there is significant existing test evidence for the 
fuselage, but very little for the wing. In this case, the FAA expects 
that demonstrating freedom from WFD for the wing would be based 
primarily on service experience; for the fuselage, it would be based 
primarily on service experience and test evidence. Advisory Circular 
120-YY further describes considerations for when service experience 
could be used to supplement existing fatigue testing that is limited to 
certain major components of the airplane, such as the fuselage.

[[Page 69764]]

    The FAA has used the term ``analysis'' to include fatigue and 
damage tolerance analyses. Teardown inspections of in-service airplanes 
and fatigue test articles should be performed to the degree necessary 
to validate that the test evidence, analysis, and service experience 
are representative of the fatigue performance of the airplane out to 
the LOV. Design approval holders must explain in their certification 
plan how they intend to substantiate their proposed LOV. The FAA has 
revised AC 120-YY to provide further guidance on the steps to take for 
establishing an LOV.
    As discussed in the NPRM, design approval holders are not required 
to identify and develop maintenance actions if they can show that such 
actions are not necessary to prevent WFD before the airplanes reach 
LOV. If they choose to establish LOVs that rely upon maintenance 
actions to prevent WFD before the LOV, they must identify those actions 
and, unless the necessary service information already exists, develop 
the service information in accordance with a binding schedule approved 
by the FAA. Those actions would then be mandated, not by today's rule, 
but by future airworthiness directives.
    To be approved, the ``binding schedule'' for necessary maintenance 
actions must ensure that the service information is provided in a 
``timely manner.'' In the NPRM, the FAA explained that the purpose of 
this requirement was to enable the FAA to issue the necessary 
airworthiness directives in time to allow operators to accomplish these 
actions during normal maintenance. The intent is to allow design 
approval holders the flexibility to focus their efforts on initially 
developing service information on those maintenance actions that must 
be accomplished first. At the same time, the FAA expects design 
approval holders to devote sufficient resources to these efforts so 
that:
     The service information is available when the FAA needs it 
to initiate the airworthiness directive rulemaking process, including 
providing public notice and opportunity to comment; and
     The resulting airworthiness directives will provide 
sufficient compliance times so that the required actions can be 
accomplished without disrupting operators' normal maintenance 
schedules.
    Airbus stated that the analysis is the driver for substantiating 
LOVs and that test evidence supports the analysis.
    Analysis methods are used in combination with the engineering data 
to characterize WFD behavior to the degree necessary to determine if 
maintenance actions are required prior to the proposed LOV. As a 
result, test evidence and analysis are both required to demonstrate 
freedom from WFD. This is consistent with the existing requirements of 
Sec.  25.571 at Amendment 25-96.
    We agree that a design approval holder may not have both service 
experience and teardown inspection results available to use as part of 
its compliance data. We have modified the requirement so that a design 
approval holder may have either service experience or service 
experience and results of teardown inspections. The change is follows:
    ``This demonstration must include an evaluation of airplane 
structural configurations and be supported by test evidence and 
analysis at a minimum and, if available, service experience, or service 
experience and teardown inspection results, of high-time airplanes of 
similar structural design, accounting for differences in operating 
conditions and procedures.''

I. How To Extend LOVs

    Proposed Sec.  25.1811 provided that any person could apply to 
extend an operational limit, using a process similar to that for 
establishing the initial operational limit. The configuration to be 
evaluated would consist of not only all model variations and 
derivatives approved under the type certificate for which the extension 
is sought, but also all structural repairs, alterations, and 
modifications to those airplanes, whether mandated by airworthiness 
directive or not.
    Section 26.23(b) of this final rule (proposed as Sec.  25.1811) 
contains requirements for obtaining approval of an extended LOV that 
corresponds to the period of time, stated as a number of total 
accumulated flight cycles or flight hours or both, beyond an existing 
LOV during which it is demonstrated that WFD will not occur in the 
airplane. This demonstration must include an evaluation of airplane 
structural configurations and be supported by test evidence and 
analysis at a minimum and, if available, service experience, or service 
experience and teardown inspection results of high-time airplanes of 
similar structural design, accounting for differences in operating 
conditions and procedures. Requirements for this section are the same 
as those for establishing an LOV. The FAA has removed the requirement 
to evaluate repairs, alterations, and modifications from Sec.  26.23.
1. Change the Procedure for Extending LOVs
    Industry representatives on the AAWG, ATA, Cessna, Airbus, United 
Parcel Service, FedEx, Boeing, and American Airlines stated that the 
means proposed in Sec.  25.1811 for extending an operational limit is 
administratively difficult, impractical, and technically unachievable. 
The commenters expressed doubt that the proposed process could be 
realistically or uniformly accomplished because different operators 
will be involved in extending the LOV for the same airplane model. 
Furthermore, said the commenters, it is unlikely that any single 
operator has the information necessary to obtain an extended LOV. The 
cost, and uncertainty about the outcome of the evaluation, would make 
this process nearly impossible for an operator to attempt.
    The commenters added that extending an LOV would need to be done by 
addressing each individual airplane, identified by tail number, whereas 
the maintenance actions which support the initial LOV are based on 
statistics pertaining to behavior of the entire fleet of a particular 
model. Thus, the method of determining maintenance actions to preclude 
WFD out to the LOV is not valid for a single airplane. The AAWG 
industry representatives recommended that establishing an extended LOV 
and evaluating repairs, alterations, and modifications be a sequential 
process. The first step would be to establish the extended LOV. The 
second step would be for each design approval holder for a modification 
to evaluate its own design relative to the extended LOV and obtain a 
separate, independent approval for its design. The operator would 
continue to be responsible for assembling all maintenance requirements, 
depending on actual airplane configuration, and for obtaining approval 
of the maintenance program from the principal maintenance inspector. 
Such a process is similar to industry proposals for compliance with the 
Aging Airplane Safety Final Rule.
    Several commenters also remarked that the administrative process 
for obtaining an amended type certificate or supplemental type 
certificate will be extraordinarily difficult to manage because 
manufacturers, operators, and holders of supplemental type certificates 
do not necessarily have access to each other's proprietary information. 
The existing business and legal agreements in place did not contemplate 
the high degree of data disclosure that will be required to develop WFD 
guidance material and

[[Page 69765]]

data needed for an amended type certificate or supplemental type 
certificate. Furthermore, many transport airplanes are converted to 
operate in different roles than those for which they were originally 
designed. Often operators cannot obtain support or design data from 
design approval holders because the latter have concerns about 
liability, are no longer in business, or are more motivated to sell new 
airplanes than to support old ones.
    Several commenters recommended that the FAA delete proposed Sec.  
25.1811 and revise proposed Sec.  25.1807 to allow extension of an LOV 
by a process approved by the Administrator. They base their 
recommendation on the fact that the technical requirements for 
establishing an LOV are no different from those for establishing an 
extended LOV.
    The FAA agrees that, given the extensive information required to 
develop guidelines for including a WFD evaluation of repairs, 
alterations, and modifications, the proposed requirements for extending 
the LOV needed to be changed. As discussed earlier, the FAA has removed 
those requirements. As a result, this final rule includes requirements 
for extending an LOV based on the original LOV airplane configuration 
plus all new structural modifications or replacements mandated by 
airworthiness directives. The FAA has revised requirements of Sec.  
26.23(b) to be consistent with Sec.  26.21(b). As previously stated, if 
our research demonstrates that additional actions are needed to address 
risks for repairs, alterations, and modifications, the FAA will 
consider further rulemaking.
    The FAA does not agree with the suggestions to allow extension of 
an LOV using a process approved by the Administrator. In this final 
rule, requirements for extending an LOV are similar to those for 
establishing the first LOV. However, the design approval holder is not 
required to develop the data to support an extended LOV because such 
extensions are optional. The extended LOV and associated maintenance 
actions (inspections, modifications, or replacements) must be defined 
within the Airworthiness Limitations section for the airplane. This 
requirement is unchanged from the proposed requirements of Sec.  
25.1811(b) of the NPRM. As stated in the NPRM, the FAA intends to use 
airworthiness directives to mandate any maintenance actions necessary 
to reach the LOV established under Sec.  26.21, so that operators will 
have an opportunity to comment on the proposed maintenance actions. It 
is not necessary to use this process for extensions of the LOV, 
however, because the extended LOV would include all maintenance actions 
at the time of approval. For these reasons, the FAA has kept 
requirements for extending an LOV separate from Sec.  26.21. The FAA 
has revised AC 120-YY to provide guidance on establishing an extended 
LOV.
2. Evaluation of Repairs, Alterations, and Modifications for an LOV 
Extension
    EASA stated that certain existing repairs, alterations, and 
modifications should be evaluated for WFD when the LOV is being 
extended. EASA states that the risk of WFD increases for repairs, 
alterations, and modifications as airplanes age.
    As discussed elsewhere in this document, an extension should be 
based on the airplane's structural configuration, just as the initial 
LOV is. Persons establishing extensions to LOVs may identify conditions 
or limitations in the Airworthiness Limitations section of the 
Instructions for Continued Airworthiness that apply to the extensions. 
For example, the LOV extension may only be valid for airplanes that 
operate at a certain cabin differential pressure or maximum takeoff 
gross weight. Operators may have to evaluate their airplanes and take 
certain actions prior to incorporating any extensions. AC 120-YY 
provides additional guidance on this.
3. Alternate Means of Compliance (AMOCs)
    APA commented that operators should not be allowed alternate means 
of compliance (AMOCs) for the WFD rule because, it says, if the FAA 
allows AMOCs as it does with airworthiness directives, the ability to 
collect data and track compliance will be greatly complicated. Each 
operator, said the commenter, will comply in a manner with the least 
financial impact to its company. This may or may not be supported by 
the ongoing efforts of the original equipment manufacturers to develop 
analysis techniques and procedures. It will also add significant 
financial costs to the original equipment manufacturers and the FAA to 
support, track, and verify each AMOC.
    The initial LOV is established and approved under Sec.  26.21 or 
Sec.  25.571. Any extension to the initial LOV or any subsequent LOV is 
established and approved under Sec.  26.23. The FAA does not issue 
AMOCs for these regulations. Any deviation from a rule is handled via 
the procedures contained in 14 CFR part 11.
    Under Sec.  26.21, any maintenance actions needed to support the 
initial LOV will be mandated by airworthiness directives, and 
compliance with those airworthiness directives and the ability to apply 
for an AMOC for those maintenance actions will not involve procedures 
that are any different from those used for airworthiness directives 
today. An AMOC for the maintenance actions for an initial LOV will not 
affect the LOV itself.
    Under Sec.  26.23, however, any maintenance actions developed to 
support the extended LOV will be incorporated into the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness. 
The maintenance actions for extended LOVs will not be published in 
airworthiness directives.
4. Extension Procedure Doesn't Allow Public Comment
    ATA and Northwest Airlines stated that the proposed rule does not 
permit the public to comment on extensions to LOVs and the maintenance 
actions that support them. Extensions to LOVs mandated by airworthiness 
directive would allow the opportunity for public comments on extended 
LOVs.
    Although mandating LOV extensions by airworthiness directive would 
allow the public the opportunity to comment, the FAA does not agree 
with the suggestions to use airworthiness directives to allow extension 
of an LOV. This is for two reasons:
     Approving an extended LOV isn't rulemaking; it's a finding 
of compliance with the applicable regulatory standard (i.e., freedom 
from WFD).
     If the FAA doesn't extend the LOV, or subsequent 
extensions of that LOV, there's no unsafe condition justifying an 
airworthiness directive, because affected airplanes are grounded when 
they reach the LOV.
    The FAA has revised AC 120-YY to provide guidance on establishing 
an extended LOV.
    The AAWG recommended in its Task 3 Report that design approval 
holders and operators work together in establishing LOVs and LOV 
extensions. Under today's rule, the FAA expects that design approval 
holders and operators will work together when persons are seeking 
approval for extended LOVs.

J. Applicability for Existing Airplanes

    The rule proposed in the NPRM would apply to existing transport 
category airplanes with a maximum takeoff gross weight greater than 
75,000 pounds, by virtue of either the original type certification of 
the airplane or a later increase, that are operated under part 121 or 
129.

[[Page 69766]]

    This final rule applies to certain existing transport category, 
turbine-powered airplanes with a maximum takeoff gross weight greater 
than 75,000 pounds and a type certificate issued after January 1, 1958, 
regardless of whether the maximum takeoff gross weight is a result of 
an original type certificate or a later design change. In addition, it 
applies to transport category, turbine-powered airplanes with a type 
certificate issued after January 1, 1958, if a design change approval 
for which application is made after the effective date of the rule has 
the effect of reducing the maximum takeoff gross weight from greater 
than 75,000 pounds to 75,000 pounds or less. It also applies to 
operators of those airplanes being operated under part 121 or 129.
1. Type Certificates Issued After January 1, 1958
    As proposed, applicability of the rule was not limited to turbine-
powered airplanes with type certificates issued after January 1, 1958. 
Everts Air Cargo requested that McDonnell Douglas Model DC-6 airplanes 
be excluded from applicability, and Boeing requested that both the DC-6 
and DC-7 be excluded. Everts Air Cargo stated that its airplanes are 
non-pressurized, which should reduce the risk that they would develop 
WFD. Both Boeing and Everts pointed out that Sec. Sec.  121.370a and 
129.16 of the Aging Airplane Safety Final Rule apply only to certain 
transport category, turbine-powered airplanes with a type certificate 
issued after January 1, 1958. The commenters recommended that the rule 
pertaining to WFD apply only to those same airplanes.
    The FAA agrees that certain parts of the applicability of this 
final rule should align with the Damage Tolerance Data Rule and the 
Aging Airplane Safety Final Rule and other aging airplane rules, such 
as EAPAS/FTS. The McDonnell Douglas DC-6 and DC-7 airplanes have not 
had a damage tolerance assessment and have not been included in the 
Damage Tolerance Data Rule. In addition, the risk from excluding these 
airplanes is small because there are so few of them.
    Therefore, in this final rule the FAA has added the phrase 
``transport category, turbine-powered airplanes with a type certificate 
issued after January 1, 1958'' to the applicability provisions of Sec.  
26.21 and to the operating rules. The change means that the following 
airplanes, which would have been affected by the proposal, are not 
subject to this final rule:
     McDonnell Douglas Models DC-6 and DC-7.
     Lockheed Model 1649A-98.
     Lockheed Model 1049 Series.
     Lockheed Models 49-46, 149-46, 649-79, 649A-79, 749-79, 
and 749A-79.
2. Original Type Certification
    The applicability provision in proposed Sec.  25.1807 included 
airplanes with maximum takeoff gross weights exceeding 75,000 pounds, 
as approved during original type certification, as well as airplanes 
with lower weights that had been increased to greater than 75,000 
pounds through later design changes. This applicability provision was 
intended to address two situations. In the past, some designers and 
operators avoided applying requirements mandated only for airplanes 
over a specific capacity by receiving a design change approval for a 
slightly lower capacity. By referencing the capacity resulting from 
original type certification, the NPRM removed this means of avoiding 
compliance.
    Similarly, an airplane design could be originally certified with a 
capacity lower than the minimum specified in the rule, but through 
later design changes, the capacity has been increased above this 
minimum. The reference in the NPRM to a later increase in capacity was 
intended to ensure that, if this occurs, the design would have to meet 
the requirements of the rule.
    The applicability proposed in the NPRM did not distinguish among 
design changes based on whether their date of application for design 
approval occurred before or after the rule's effective date. That 
provision in proposed Sec.  25.1807 is similar to that for the EAPAS/
FTS, Fuel Tank Flammability, and Damage Tolerance Data Rules. In 
addition, the reference to capacity resulting from original type 
certification is common to proposed Sec.  25.1807 and the other rules. 
The agency has determined that the approach to applicability under 
today's rule should be slightly different from that used in previous 
rules. This is to avoid requiring design approval holders to establish 
LOVs for models that have maximum takeoff gross weights that were 
decreased to 75,000 pounds or less by an amended type certificate or 
supplemental type certificate before the effective date of today's 
rule. Applicants for such design changes in the past could not have 
designed the airplanes' capacities to avoid complying with today's 
requirements, and it is not our intent to include them in the 
applicability of this final rule.
    The FAA has revised this section (now Sec.  26.21) to apply to 
transport category, turbine-powered airplanes with a maximum takeoff 
gross weight greater than 75,000 pounds and a type certificate issued 
after January 1, 1958, regardless of whether the maximum takeoff gross 
weight is a result of an original type certificate or a later design 
change. This section also applies to transport category, turbine-
powered airplanes with a type certificate issued after January 1, 1958, 
if a design change approval, for which application is made after the 
effective date of the rule, has the effect of reducing the maximum 
takeoff gross weight from greater than 75,000 pounds to 75,000 pounds 
or less.
    The FAA has also revised the applicability of Sec. Sec.  121.1115 
and 129.115 to be consistent with the applicability of Sec.  26.21 for 
existing airplanes. For future airplanes for which an LOV is approved 
in accordance with Sec.  25.571 of today's rule, we have retained the 
requirement that Sec. Sec.  121.1115 and 129.115 apply to operators of 
U.S.-registered transport category, turbine-powered airplanes, 
regardless of the maximum takeoff gross weight. For future design 
changes reducing the maximum takeoff gross weight from greater than 
75,000 pounds to 75,000 pounds or less, the compliance date for 
operators is 30 months after the effective date of the rule, or the 
date of design change approval, or the date specified in the plan 
approved under Sec.  25.571(b), whichever occurs latest. For these 
design changes, unless or until the design approval holder complies 
with Sec.  26.21 by establishing a new LOV, the LOV applying to the 
airplane in the absence of the design change would still apply.
3. Airplane Configuration
    This final rule requires that holders of type certificates for 
existing airplanes evaluate certain configurations of those airplanes 
for susceptibility to WFD and use the results of the evaluation to set 
LOVs for those airplanes. The configurations to be evaluated are:
     All model variations and derivatives approved under the 
type certificate, and
     All structural modifications and replacements to those 
airplanes which were mandated by airworthiness directives issued to 
address any configuration developed by the design approval holder.
    In the NPRM, the FAA proposed evaluation of the same airplane 
configurations.
    In their comments, the industry representatives on the AAWG, 
Boeing, and Airbus expressed concern about the proposed requirement to 
evaluate all structural modifications and

[[Page 69767]]

replacements mandated by airworthiness directives. Airbus stated that 
this approach deviates from all previous industry recommendations and 
will lead to a significant increase in configurations to be assessed. 
The industry representatives on the AAWG, Boeing, and Airbus requested 
that the FAA reconsider this requirement and focus only on 
airworthiness directives which have been issued specifically to address 
WFD.
    The FAA issues many airworthiness directives which require 
structural modifications or replacements not intended to address WFD. 
These required modifications or replacements, however, may affect 
susceptibility of a structure to WFD. A modification might introduce 
new details that cause a structure which was previously not susceptible 
to WFD to become susceptible, or make a change that increases 
susceptibility so that previously established maintenance actions need 
to be modified. Because today's rule is intended to address the 
potential for WFD in airplanes as they are actually configured, we must 
address these required modifications. It would serve no useful purpose 
to evaluate structural configurations which no longer exist in service 
because airworthiness directives have required modifications to those 
configurations.
    Modifications mandated by airworthiness directives are much fewer 
in number than other modifications, and they generally affect airplanes 
of the same model in the same way. Many modifications mandated by 
airworthiness directives would not affect the potential for WFD; others 
could.\30\ Therefore, the FAA is today issuing this requirement as 
proposed.
---------------------------------------------------------------------------

    \30\ Advisory Circular 120-YY provides guidance on which 
modifications mandated by airworthiness directives should be 
assessed by the design approval holder.
---------------------------------------------------------------------------

4. Weight Cutoff
    In the preamble to the proposed rule, the FAA stated that the 
agency had considered applying the rule to all existing transport 
category airplanes, regardless of the maximum takeoff gross weight. The 
FAA acknowledged that using a weight cutoff of greater than 75,000 
pounds excludes approximately 1,600 regional jets operating under parts 
121 or 129, giving the impression that this rule might not align with 
our ``One Level of Safety'' initiative. However, the FAA justifies the 
proposed weight cutoff on the basis of the relatively young age of the 
regional jet fleet. Because those airplanes are younger, they have a 
low present risk for WFD.
    Embraer agreed that existing regional jet airplanes should not be 
subject to the rule at this time, stating that the airplanes have 
typically been certificated to damage tolerance requirements. Other 
commenters--such as the National Transportation Safety Board, Transport 
Canada, the Air Line Pilots Association (ALPA), EASA, and an individual 
commenter--did not agree, because the regional jets are at risk of 
developing WFD as they accumulate flight cycles just as larger 
airplanes are. The ALPA recommended that the FAA form a study group to 
assess WFD in lighter airplanes. Pending a detailed risk analysis, the 
association suggested a weight cutoff of 12,000 pounds.
    The 75,000 pound weight cutoff was based on recommendations from 
the AAWG for WFD rulemaking. The overwhelming majority of passengers 
and cargo are carried by airplanes with a maximum gross takeoff weight 
of greater than 75,000 pounds. Inclusion of airplanes below that limit 
and above 12,500 pounds is under study by the FAA and if service 
experience shows a need to include those airplanes, rulemaking will be 
considered to include them.
    The FAA's highest priority is to address the oldest airplanes at 
highest risk of WFD--namely, airplanes with a maximum takeoff gross 
weight greater than 75,000 pounds. However, the FAA recognizes that the 
lighter and relatively younger regional jets will also be at risk of 
developing WFD as they accumulate flight cycles. We will reassess the 
fleet, including those airplanes below 75,000 pounds, after this rule 
has been implemented, to determine whether further rulemaking is 
necessary.
5. Default LOVs and Excluded Airplanes
a. Table 1--Default LOVs
    In the proposed operational requirements in the NPRM, the FAA 
inadvertently created an ambiguity regarding the obligations of 
operators of airplanes for which the design approval holder might fail 
to establish an LOV as required. While the FAA fully anticipates that 
affected design approval holders will comply with the requirements of 
this final rule, there is a need to clearly provide for what happens if 
one or more does not. As proposed, paragraph (a) of Sec. Sec.  121.1115 
and 129.115 would apply to operators of airplanes for which an LOV 
``has been established.'' Paragraph (b) of these sections requires that 
operators incorporate approved LOVs.
    Our expectation was that, if a design approval holder failed to 
comply with the requirement to obtain approval for an LOV, the operator 
or operators, in order to continue to operate the affected airplanes, 
would themselves obtain the necessary approval. Because they would not 
have access to the design approval holder's data necessary to perform a 
WFD evaluation, they would likely have to rely on the design service 
goals and extended service goals set forth in Table 3 of the NPRM (see 
below). As stated in the NPRM, ``After June 18, 2008, an affected 
operator could not operate an airplane unless the operator has 
incorporated an Airworthiness Limitations section approved under 
Appendix H to part 25 or Sec.  25.1807 into its maintenance program.''
    The FAA now recognizes that the final rule should explicitly define 
operators' obligations if the design approval holder fails to comply. 
Therefore, the FAA has revised the operational rules to state that, in 
the absence of an approved LOV, the operator must incorporate the 
applicable LOV specified in Table 1 \31\ of either Sec.  121.1115 or 
Sec.  129.115. The table also adds flight hour numbers for design 
service goals for airplanes for which that information was available.
---------------------------------------------------------------------------

    \31\ To develop Table 1, the FAA added airplanes to Table 3, 
deleted airplanes from Table 3, and split Boeing Models 737, 747, 
and 777 airplanes into two groups. These airplanes were added: 
Airbus A318 and A380; Bombardier CL-600 (2D15 and 2D24); and Embraer 
ERJ-170 and ERJ-190. The following airplane models were deleted: 
Boeing 707 and 720; Bombardier CL-44 and BD-700; British Aerospace 
Airbus, Ltd. BAC 1-11; British Aerospace (Commercial Aircraft) Ltd. 
Armstrong Whitworth Argosy A.W. 650 Series 101; BAE Systems 
(Operations) Ltd BAe 146A (all models), Avro 146 RJ70A, Avro RJ85A, 
and Avro RJ100A.
---------------------------------------------------------------------------

    The inclusion of default LOVs in Table 1 does not prevent an 
operator from developing its own LOV under Sec.  26.23 of this final 
rule. The rule specifies that--
     The design approval holder must establish an LOV, and
     If an LOV is not approved, an operator must use the 
default LOV in Table 1. If an operator later chooses to establish an 
LOV under Sec.  26.23, that LOV will be considered an extended LOV.
    This provision eliminates any need for operators to obtain a 
separate approval for these ``default'' LOVs. It also eliminates the 
risk that a relatively young airplane would be grounded as of an 
operator's compliance date simply because the FAA had not approved an 
LOV for that airplane.
    Boeing stated that the default LOVs published in the Technical 
Document are without context and could be misused. Boeing said that it 
could provide more appropriate numbers to

[[Page 69768]]

use, but that these numbers should be removed from the rule because 
Boeing intends to comply with the rule.
    The default LOVs in Table 2 of Sec.  121.1115 and Sec.  129.115 are 
intended to be used by persons who may choose to operate one of the 
excluded airplanes. They may also be used by other operators if a 
design approval holder is late in establishing an LOV, in order to 
prevent airplanes with fewer accumulated flight cycles and flight hours 
than the default LOV from being grounded. A few airplanes, such as the 
Airbus A380, already have an operational limitation included in their 
Airworthiness Limitations section. These are referenced in the table by 
a NOTE, and may be used as a default LOV.

           Figure 3--Comparison of NPRM Design and Extended Service Goals and Final Rule Default LOVs
----------------------------------------------------------------------------------------------------------------
                                                 NPRM table 3             Final rule Sec.  Sec.   121.1115 and
                                        ------------------------------              129.115 table 1
             Airplane model                                           ------------------------------------------
                                          Design and Extended Service     Default LOVs [flight cycles (FC) or
                                             Goals (flight cycles)                 flight hours (FH)]
----------------------------------------------------------------------------------------------------------------
Airbus:
    A300 B2 Series \32\................  48,000......................  48,000 FC
    A300 B4-100 Series \33\............  40,000......................  40,000 FC
    A300 B4-203........................  34,000......................  34,000 FC
    A300-600 Series \34\...............  30,000......................  30,000 FC/67,500 FH
    A310-200 Series (all models).......  40,000......................  40,000 FC/60,000 FH
    A310-300 Series (all models).......  35,000......................  35,000 FC/60,000 FH
    A318 Series (all models)...........  None provided...............  48,000 FC/60,000 FH
    A319 Series (all models)...........  48,000......................  48,000 FC/60,000 FH
    A320-100 Series (all models) \35\..  48,000......................  48,000 FC/48,000 FH
    A320-200 Series (all models) \35\..  48,000......................  48,000 FC/60,000 FH
    A321 Series (all models)...........  48,000......................  48,000 FC/60,000 FH
    A330-200, -300 Series (except WV050  40,000......................  40,000 FC/60,000 FH
     family) (non enhanced) \36\.
    A330-200, -300 Series WV050 family   40,000......................  33,000 FC/100,000 FH
     (enhanced) \36\.
    A330-200 Freighter Series..........  None provided...............  NOTE \38\
    A340-200, 300 Series(except WV 027   20,000......................  20,000 FC/80,000 FH
     and WV050 family) (non enhanced)
     \37\.
    A340-200, 300 Series WV 027 (non     20,000......................  30,000 FC/60,000 FH
     enhanced) \37\.
    A340-300 SeriesWV050 family          20,000......................  20,000 FC/100,000 FH
     (enhanced) \37\.
    A340-500, 600 Series (all models)    20,000......................  16,600 FC/100,000 FH
     \37\.
    A380-800 Series (all models).......  None provided...............  NOTE \39\
Boeing:
    Boeing 707 (-100 Series and -200     20,000......................  Excluded per Sec.   26.21(g)
     Series).
    Boeing 707 (-300 Series and -400     20,000......................  Excluded per Sec.   26.21(g)
     Series).
    717 (all models)...................  60,000......................  60,000 FC/60,000 FH
    Boeing 720.........................  30,000......................  Excluded per Sec.   26.21(g)
    727 (all models)...................  60,000......................  60,000 FC
    737 (Classics): 737-100, -200, -     75,000......................  75,000 FC
     200C, -300, -400, -500 \40\.
    737 (NG): 737-600, -700, -700C,      75,000......................  75,000 FC
     800, 900 \40\.
    737-900ER..........................  None provided...............  75,000 FC
    747 (Classics): 747-100, -100B, -    20,000......................  20,000 FC
     100B SUD, -200B, -200C, -200F, -
     300, -747SP, 747SR \41\.
    747-400: 747-400, -400D, -400F \41\  20,000......................  20,000 FC
    757 (all models)...................  50,000......................  50,000 FC
    767 (all models)...................  50,000......................  50,000 FC
    777-200, -300 \42\.................  44,000......................  40,000 FC
    777-200LR, 777-300ER \42\..........  44,000......................  40,000 FC
    777F...............................  None provided...............  11,000 FC
Bombardier:
    CL-44D4 and CL-44J.................  20,000......................  Excluded per Sec.   26.21(g)
    CL-600: 2D15 (Regional Jet Series    None provided...............  60,000 FC
     705), 2D24 (Regional Jet Series
     900).
British Aerospace Airbus, Ltd.:
    BAC 1-11 (all models)..............  85,000......................  Excluded per Sec.   26.21(g)
British Aerospace (Commercial Aircraft)
 Ltd.:
    Armstrong Whitworth Argosy A.W. 650  20,000......................  Excluded per Sec.   26.21(g)
     Series 101.
BAE Systems (Operations) Ltd.:
    BAE 46 (all models) and Avro 146     50,000......................  Excluded per Sec.   26.21(g)
     RJ70A, RJ85A and RJ100A (all
     models).
Embraer:
    ERJ 170 (all models)...............  None provided...............  NOTE \43\
    ERJ 190 (all models)...............  None provided...............  NOTE \44\
Fokker:
    F.28 Mark 70, Mark 100 (all models)  90,000......................  90,000 FC
Lockheed:
    300-50A01 (USAF C 141A)............  20,000......................  Excluded per Sec.   26.21(g)
    L-1011 (all models)................  36,000......................  36,000 FC
    188 (all models)...................  26,600......................  26,600 FC

[[Page 69769]]

 
    382 (all models)...................  20,000......................  20,000 FC/50,000 FH
    1649A-98...........................  20,000......................  Excluded per Sec.   26.21(a)
    1049-54, 1049B-55, 1049C-55, 1049D-  20,000......................  Excluded per Sec.   26.21(a)
     55, 1049E-55, 1049F-55, 1049G-8249-
     46, 149-46, 649-79, 649A-79.
    749-79, 749A-79....................  20,000......................  Excluded per Sec.   26.21(a)
McDonnell Douglas:
    DC-6 \45\..........................  20,000......................  Excluded per Sec.   26.21(a)
    DC-6A (all models) \45\............  20,000......................  Excluded per Sec.   26.21(a)
    DC-6B (all models) \45\............  20,000......................  Excluded per Sec.   26.21(a)
    DC-7 (all models) \45\.............  20,000......................  Excluded per Sec.   26.21(a)
    DC-8, -8F (all models).............  50,000......................  50,000 FC/50,000 FH
    DC-9 (all models)..................  100,000.....................  100,000 FC/100,000 FH
    MD-80 (all models).................  50,000......................  50,000 FC/50,000 FH
    MD-90 (all models) \46\............  60,000......................  60,000 FC/90,000 FH
    DC-10-10, -15 (all models).........  42,000......................  42,000 FC/60,000 FH
    DC-10-30, -40, -10F, -30F, -40F      30,000......................  30,000 FC/60,000 FH
     (all models).
    MD-10-10F (all models).............  42,000......................  42,000 FC/60,000FH
    MD-10-30F (all models).............  30,000......................  30,000 FC/60,000 FH
    MD-11, -11F (all models)...........  20,000......................  20,000 FC/60,000 FH
Airplanes with Maximum Takeoff Gross
 Weight Changes:
    All airplanes whose maximum takeoff  Design service goals and      There are no default LOVs for airplanes
     gross weight has been decreased to   extended service goals for    whose weight has been changed.
     75,000 pounds or below after         airplanes whose weight has
     January 14, 2011 or increased to     been changed are unknown.
     greater than 75,000 pounds at any
     time by an amended type
     certificate or supplemental type
     certificate.
----------------------------------------------------------------------------------------------------------------
\32\ Listed as A300 B2-1A, B2-1C and B2K-3C in the NPRM.
\33\ Listed as A300 B4-2C and B4-103 in the NPRM.
\34\ Listed as A300 B4-600 Series, B4-600R Series, and F4-600R Series in the NPRM.
\35\ Listed as A320 (all models) in the NPRM.
\36\ Listed as A330 (all models) in the NPRM.
\37\ Listed as A340 (all models) in the NPRM.
\38\ Airplane operation limitation is stated in the Airworthiness Limitation section.
\39\ Airplane operation limitation is stated in the Airworthiness Limitation section.
\40\ Listed as Boeing 737 in the NPRM.
\41\ Listed as Boeing 747 in the NPRM.
\42\ Listed as Boeing 777 in the NPRM.
\43\ Airplane operation limitation is stated in the Airworthiness Limitation section.
\44\ Airplane operation limitation is stated in the Airworthiness Limitation section.
\45\ Airplane certificated before 1958.
\46\ Listed as MD-90-30 in the NPRM.

b. Table 2--Airplanes excluded from Sec.  26.21
    Section 26.21 specifically excludes models of airplanes from 
today's rule if no airplanes of that model are operating under part 121 
or 129. Today's revisions to parts 121 and 129 requiring that operators 
incorporate LOVs into their structural maintenance programs include 
applicability to operators of airplanes that have been excluded under 
Sec.  26.21 should the operator later decide to operate one of them.
    In the NPRM, the FAA proposed excluding airplanes not operated 
under part 121 or 129. The agency proposed exclusion from the rule for:
     Bombardier BD-700.
     Gulfstream GV.
     Gulfstream GV-SP.
     British Aerospace, Aircraft Group, and Societe Nationale 
Industrielle Aerospatiale Concorde Type 1.
    The FAA requested comments on the feasibility and benefits of 
including or excluding these airplanes. The agency also requested 
comments on the feasibility of including or excluding any other 
transport category airplanes with a maximum takeoff gross weight 
greater than 75,000 pounds from the requirements of this provision, 
whether or not they are operated under part 121 or 129.
    Several commenters disagreed with the applicability of the rule, as 
proposed. The National Transportation Safety Board recommended that the 
final rule also apply to airplanes operated under part 135 because they 
may be at equal or greater risk of developing WFD compared to those 
operated under parts 121 or 129.
    An individual commenter suggested that the FAA delete the list of 
airplanes proposed for exclusion because it gives preferential 
treatment to certain airplanes. This commenter added that an operator 
had planned to use Gulfstream GV airplanes for part 121 operations but 
chose not to do so only for financial reasons. If an operator did 
decide to operate an excluded airplane under part 121 or 129, said the 
commenter, there would be no operational limit and no associated 
maintenance actions to preclude WFD in that airplane. Although this 
commenter did not support having a list of excluded airplanes in the 
rule, he suggested--based on the agency's stated rationale in the 
NPRM--that we add the following airplanes to the list:
     The Douglas DC-6, DC-6A, and DC-7.
     The Lockheed 049, 149, 649, 749, 1049, 1649, 188, 300, and 
382.
     The Boeing 707 and 720.

[[Page 69770]]

    We have reconsidered our rationale for the list of excluded 
airplanes proposed in the NPRM. Those airplanes have a maximum takeoff 
gross weight greater than 75,000 pounds but are not currently operating 
under part 121 or 129. Therefore, there is no reason to require the 
design approval holders to establish LOVs for them. We have decided to 
retain on the list the models originally proposed for exclusion from 
the rule and, in response to comments, and to be consistent with other 
aging airplane rules, have added other models which are not operated 
under part 121 or 129. The complete list is shown below.
    (1) Bombardier BD-700.
    (2) Bombardier CL-44.
    (3) Gulfstream GV.
    (4) Gulfstream GV-SP.
    (5) British Aerospace, Aircraft Group, and Societe Nationale 
Industrielle Aerospatiale Concorde Type 1.
    (6) British Aerospace (Commercial Aircraft) Ltd., Armstrong 
Whitworth Argosy A.W. 650 Series 101.
    (7) British Aerospace Airbus, Ltd., BAC 1-11.
    (8) BAE Systems (Operations) Ltd., BAe 146.
    (9) BAE Systems (Operations) Ltd., Avro 146.
    (10) Lockheed 300-50A01 (USAF C141A).
    (11) Boeing 707.
    (12) Boeing 720.
    (13) deHavilland D.H. 106 Comet 4C.
    (14) Ilyushin Aviation IL-96T.
    (15) Bristol Aircraft Britannia 305.
    (16) Avions Marcel Dassault-Breguet Aviation Mercure 100C.
    (17) Airbus Caravelle.
    (18) D & R Nevada, LLC, Convair Model 22.
    (19) D & R Nevada, LLC, Convair Model 23M.
    The FAA recognizes that it is possible--as suggested by the 
individual commenter--that in the future an operator could decide to 
operate an ``excluded'' airplane under part 121 or 129. Therefore, in 
this final rule Sec. Sec.  121.1115 and 129.115 are revised to provide 
that no airplane listed in Sec.  26.21 can be operated under part 121 
or 129 unless an LOV for the airplane has been incorporated into the 
operator's structural maintenance program. The operational rules state 
that, in the absence of an approved LOV, the operator must incorporate 
the applicable default LOV specified in Table 2 of either Sec. Sec.  
121.1115 or 129.115. Those default LOVs are based on Table 3 of the 
NPRM. As stated in the NPRM, Table 3 used design service goals and 
extended service goals that were based on information from design 
approval holders or on a conservative estimate by the FAA. It did not 
include the Comet 4C, IL-96T, Britannia 305, Mercure 100C, Caravelle, 
Convair Model 22, or Convair Model 23M. To develop those default LOVs, 
the FAA treated flight-cycle or flight-hour data that was available for 
those airplanes as fatigue test data and reduced it by a factor of two. 
This approach is based in part on AC 25.571-1X for new airplanes.
6. Bombardier Airplanes
    Bombardier asked for clarification of the applicability of the 
proposed rule to several of its models and their derivatives. 
Specifically, the company asked about the following airplanes:
    Models CL 600 Challenger 870 and 890: Bombardier asked whether they 
should be added to the list of excluded airplanes in proposed Sec.  
25.1807(i).
    The CL 600 Challenger 870 and 890 do not currently have type 
certificates issued by the U.S. Therefore, there are no N-registered 
airplanes operating under either part 121 or 129. As a result, this 
final rule does not apply to them at this time. However, if Bombardier 
were to apply for a U.S. type certificate before the effective date of 
this final rule, the company would have to comply by the compliance 
date in Sec.  26.21. Even if Bombardier were to apply after the 
effective date of the rule, the company would be subject to 
requirements of Sec.  26.21 because the Bilateral Aviation Safety 
Agreements (BASA) \47\ with Canada allow the U.S. to impose additional 
requirements in the interest of safety. Other airplanes in similar 
circumstances would be handled in the same way.
---------------------------------------------------------------------------

    \47\ Agreement between the Government of the United States of 
America and the Government of Canada for Promotion of Aviation 
Safety, June 12, 2000.
---------------------------------------------------------------------------

    Model CL 600 derivatives--RJ 701 ER, RJ 701 LR, all RJ 705 
airplanes, and all RJ 900 airplanes: Bombardier noted that Table 3 in 
the NPRM, titled Design and Extended Service Goals, does not list these 
models.
    The CL 600 derivatives RJ 705 and RJ 900 were inadvertently left 
off Table 3 of the NPRM. This final rule applies to Bombardier models 
RJ 705 series and RJ 900 series because their maximum takeoff gross 
weight is greater than 75,000 pounds, and they are operated under part 
121 or 129. They have been added to Table 1, which is the applicability 
table for this final rule. Today's rule does not apply to Bombardier RJ 
701 series airplanes because their maximum takeoff gross weight is not 
greater than 75,000 pounds.
    Model CL 44: These airplanes were previously exempted from the 
other aging airplane rules, both proposed and final, on the basis of 
their age and the very small number remaining in service.
    Bombardier Model CL 44 is not operated under either part 121 or 129 
and, therefore, the FAA has revised the list of excluded airplanes in 
Sec.  26.21 of today's rule to include Bombardier Model CL 44.
7. Intrastate Operations in Alaska
    Lynden Air Cargo requested that the NPRM pertaining to WFD be 
withdrawn in its entirety. Alternatively, the commenter requested that 
Lockheed Model 382 airplanes be excluded from the rule and that all air 
carriers engaged in intrastate operations in Alaska be excluded. In 
support of this request, the commenter gave the following reasons:
     There is no replacement airplane with the necessary lift 
and operational characteristics.
     The L-382 airplanes are not used to carry passengers.
     It is in the public interest to maintain the unique 
capabilities of the L-382 in Alaska where it supports remote 
communities and projects with no roads or waterways and supports the 
U.S. military during critical campaigns and the ongoing war on 
terrorism.
    Lynden Air Cargo also asked that it be excluded from Sec.  121.909.
    Senator Murkowski of Alaska and the late Senator Stevens stated 
that the rule, as proposed, would have severe consequences to residents 
and cargo carriers operating in that State. Senator Stevens referred to 
Section 1205 of the Federal Aviation Reauthorization Act of 1996 (49 
U.S.C. 40113(f)), which requires that--when modifying regulations 
affecting intrastate aviation in Alaska--the FAA consider the extent to 
which Alaska is not served by transportation modes other than aviation. 
Accordingly, Senator Stevens requested that the FAA exempt all 
intrastate operations in Alaska and the interstate operations of the 
six Lockheed L-382G airplanes operated by Lynden Air Cargo. The senator 
pointed out that the L-382G is out of production and there is no 
suitable replacement available.
    Several other commenters addressed operational limits for Lockheed 
Models L-382E and G, although they did not discuss operation of these 
airplanes in Alaska. Specifically, Transafrik International asked that 
Lockheed Models L-382E and G be removed from Table 3 or that their 
operational limit be increased to at least 60,000 cycles. The commenter 
added that the airplanes are no longer in production and there is no

[[Page 69771]]

replacement airplane able to take off and land on short, unimproved 
runways with the payloads required. A comment from Lockheed Martin 
estimated--based on certain inspections and modifications which it had 
performed on the outer and center wing structure--that the LOV for the 
Lockheed Model L-382 is 50,000 flight hours but would no doubt be 
changed to at least 75,000 flight hours, to accommodate usage in the 
fleet. Lockheed Martin also identified maintenance actions that should 
be performed on the wing structure to operate to that limit. The 
commenter stated that, regardless of any FAA decision on implementation 
of the rule, the company will continue to ensure that operators of 
Lockheed Model L-382 model aircraft are provided with inspection 
procedures and replacement actions that effectively mitigate the risk 
of failure due to WFD.
    Consistent with 49 U.S.C. 40113(f), the FAA has carefully 
considered the potential impact of this rulemaking on Alaska intrastate 
operators to determine whether intrastate service in Alaska would be 
adversely affected. Airplanes to which this final rule is applicable 
are not operated solely in intrastate commerce in Alaska. Therefore, 
contrary to the commenters' assertions, the FAA has determined that 
there would not be an adverse effect on intrastate air transportation 
in Alaska and that regulatory distinctions are not appropriate.
    The Lockheed L-382G operated by Lynden Air Cargo is operated under 
14 CFR part 121, Operating Requirements: Domestic, Flag, and 
Supplemental Operations and operates interstate as well as to foreign 
destinations. The FAA has decided against excluding the L-382G from 
requirements of Sec. Sec.  121.1115 and 129.115 for those airplanes in 
interstate operation. The safety rationale for these rules applies 
equally to that airplane. In accordance with 14 CFR part 11, Lynden Air 
Cargo may submit a petition for exemption from those rules. Such a 
petition must state (1) why granting such an exemption would be in the 
public interest and (2) why a grant of exemption would not adversely 
affect safety or how it would provide a level of safety equivalent to 
the regulation.
    Regarding Lynden Air Cargo's request for exclusion from Sec.  
121.909, that requirement, which was formerly designated as Sec.  
121.370(a), has been in effect since November 1, 2002.\48\ The FAA has 
not made any changes to that rule other than changing its section 
number.
---------------------------------------------------------------------------

    \48\ 67 FR 72726, December 6, 2002.
---------------------------------------------------------------------------

    The FAA encourages Transafrik and Lynden Air Cargo as well as other 
operators of Model L-382G to work with Lockheed Martin regarding the 
establishment of the LOV for the model.
8. Composite Structures
    The Modification and Replacement Parts Association (MARPA) and 
Airbus asked that the FAA clarify applicability of the rule to 
structure made of composite materials, and MARPA recommended that 
composite structure should be treated the same as metallic structure.
    There is an increasing trend for manufacturers to use composite 
materials to build airplanes. This structure wears differently than 
metallic structure. For example with metallic structure, repeated loads 
or environmental exposure cause fatigue cracking or corrosion. With 
composite structure, repeated loads or environmental exposure cause 
general degradation (such as cracking, delamination, and oxidative 
breakdown of the resin) and accumulation of local damage (such as 
wearing out of fastener holes and handling damage, or water ingression 
between composite layers, followed by freeze-thaw cracking of the 
core).
    The FAA issued AC 20-107B to provide guidance for certifying 
composite structures, including guidance for evaluating composite 
structure relative to the damage tolerance requirements of Sec.  
25.571.
    The objective of this final rule is to address the normal fatigue 
wear out of metallic structure. Although the trend in industry is to 
use composite structure as much as possible, a significant percentage 
of a new airplane may still be built of metal. Full-scale fatigue test 
evidence would be necessary to demonstrate that WFD will not occur in 
metallic structure of the airplane. It would also be necessary for the 
design approval holder for the airplane to develop an LOV to limit the 
operation to the point in time up to which it has been demonstrated 
that WFD will not occur in the airplane's metallic structure.
    The FAA will continue to evaluate whether rulemaking is necessary 
to address the normal wear of composite structures.

K. Harmonization

    A number of commenters, including industry representatives on the 
AAWG, FedEx, Boeing, Embraer, the National Air Cargo Association 
(NACA), AWAS, and Airbus noted that the WFD NPRM has not been 
harmonized with the European Aviation Safety Agency (EASA), which has 
issued Notice of Proposed Amendment (NPA) 05-2006 on this subject, and 
other national aviation authorities. The commenters pointed out that 
the Initial Regulatory Evaluation did not consider the cost of failing 
to harmonize the rule with other airworthiness authorities. Airbus also 
questioned whether the evaluation addressed costs associated with 
importing into the United States airplanes that have not complied with 
the rule, especially if the rule is not harmonized with other 
airworthiness authorities.
    They recommended that the FAA harmonize the rule with those 
authorities before issuing it. According to the commenters, lack of 
harmonization could cause the following problems:
    1. It could create a significant challenge to future certification 
projects, encouraging unilateral and possibly arbitrary certification 
activities.
    2. There could be a substantial negative economic impact with 
respect to the transfer, lease, or sale of aircraft between the U.S. 
and other countries. Commenters suggested that bilateral agreements be 
amended to support the transfer of used aircraft subject to the final 
rule.
    3. The FAA and EASA could have different approaches to WFD.
    4. Type certificate holders from other countries may not be given 
the same priority and allocation of FAA resources as are type 
certificate holders from this country, resulting in delayed approval 
for applications from other countries.
    Boeing, EASA, and Airbus requested that the FAA include the 
requirement to evaluate certain repairs, alterations, and modifications 
to align its requirements with those being proposed by EASA.
    The FAA is working closely with EASA and other national 
airworthiness authorities to harmonize this final rule as much as 
possible. On April 25, 2006, EASA published NPA 05-2006, entitled 
Ageing Aeroplane Structures. That notice proposed technical guidance to 
be used for developing programs for continuing structural integrity, to 
ensure that the structure of aging airplanes is adequately maintained 
throughout their operational lives. Among other things, the notice 
proposed guidance for addressing WFD in existing airplane models. The 
FAA has provided comments on that proposed rulemaking. EASA is 
considering our comments and has discussed them with us.
    Many of the changes made to our proposed rule will facilitate 
harmonization with national airworthiness authorities. Some of these 
changes are the following:

[[Page 69772]]

    1. The design approval holder requirements proposed in the NPRM as 
part 25, subpart I, are now contained in a new part 26 to harmonize 
more easily with the regulatory structure of other national 
airworthiness authorities.
    2. This final rule uses the term ``limit of validity'' rather than 
``initial operational limit'' to align more closely with other national 
airworthiness authorities.
    3. This final rule uses compliance dates that specify a phased 
approach for establishing the LOV for existing airplane models. NPA 05-
2006 links compliance dates to design service goals. As discussed 
above, the FAA has concluded that the latter approach creates 
unnecessary complexity and uncertainty. We have submitted comments 
about this matter to EASA and are in discussions about it. In terms of 
establishing an LOV, the technical guidance in AC 120-YY is consistent 
with EASA's technical guidance in NPA 05-2006.
    4. With respect to removal of requirements pertaining to repairs, 
alterations, and modifications, the FAA is working closely to harmonize 
this final rule with the rule EASA is developing but has not yet 
published for public comment.
    5. Finally, the changes to Sec.  25.571 are based on a 
recommendation of the General Structures Harmonization Working Group of 
ARAC. Development of the October 2003 recommendation pertaining to WFD 
involved harmonization between U.S. and European requirements.

L. The Regulatory Evaluation for the NPRM

    The estimated present value cost of this final rule is about $3.6 
million, while the estimated present value cost of the NPRM was 
estimated to be about $360 million. The estimated benefits of this 
final rule are worth $4.8 million in present value and are based on 
managing WFD with maintenance actions developed under this final rule 
versus the current practice of issuing airworthiness directives as WFD 
is found. The estimated present value benefits of the NPRM consisted of 
$726 million of accident prevention benefits and $83 million of 
detection benefits for total benefits of $809 million.
    We received many comments regarding the validity of the regulatory 
evaluation of the proposed rule on WFD. In general, commenters stated 
that the potential benefits of the rule seemed to be overstated, and 
the potential costs seemed to be understated. Therefore, commenters 
challenged the conclusion that the benefits of the rule justify the 
costs. The commenters included Lockheed Martin, Boeing, Airbus, 
Bombardier, NACA, the CAA, ATA, FedEx, United Parcel Service, AWAS, 
American Airlines, Lynden Air Cargo, industry representatives on the 
AAWG, and an individual commenter.
1. Benefits of Proposed Rule
    Some commenters questioned how a benefit of $726 million could be 
attributable to accident prevention when there have been no accidents 
related to WFD since the Aloha Airlines accident in 1988. The NACA and 
other commenters also argued that the regulatory evaluation makes a 
false assumption when it defines the cost benefit number for avoiding 
fleet grounding. Finally, the ATA and several other commenters 
suggested that projected benefits would decrease if the regulatory 
evaluation were updated to include data from the years 1974 through 
1983 and 2000 through 2005.
    Today's rule establishes a consistent approach to management of 
aging airplanes so that they are not operated to the point where WFD 
occurs. Thus the potential benefit of the rule is preventing 
catastrophic structural failure in flight that could result in loss of 
lives and loss of the airplane. Other benefits of the rule are costs 
avoided under the current system. Relying on the issuance of 
airworthiness directives to address WFD--whenever it happens to be 
discovered--causes unscheduled down time. The issuance of emergency 
airworthiness directives and immediately adopted rules may result in 
the unscheduled removal from service of a fleet of airplanes.
    This final rule requires a design approval holder to establish an 
LOV for an airplane that reflects the fatigue characteristics of the 
airplane structure. If the WFD evaluation determines that maintenance 
actions are necessary to reach this LOV, the FAA would adopt them 
through the normal airworthiness directive process, allowing 
opportunity for notice and comment and accomplishment of required 
actions during scheduled maintenance. As such, the costs of these 
maintenance actions would be lower than if the FAA adopted emergency 
airworthiness directives or immediately adopted rules mandating the 
same actions as a result of in-service occurrences of WFD. As discussed 
below, the FAA expects very few airplanes to be retired solely because 
they reach their LOV. We have also taken this into account.
    Our revised regulatory evaluation lists three benefits of the rule, 
namely
    (1) Prevention of accidents;
    (2) Extension of the economic life of the airplane with 
corresponding revenues from that additional economic life; and
    (3) Near elimination of emergency airworthiness directives 
pertaining to WFD, which significantly reduces downtime associated with 
urgent unscheduled maintenance. The quantified benefit of the final 
rule is based solely on this third benefit, which is valued at $9.8 
million or, evenly distributed over 20 years, a present value of 
approximately $4.8 million.
2. Costs of Proposed Rule
a. Need To Know LOVs To Determine Cost
    Some commenters stated that, if the operational limit for each 
airplane model were not known, then the cost of the rule could not be 
determined.
    In our Initial Regulatory Evaluation, the agency estimated the 
costs of initial operational limits to operators by using the design 
service goal for each airplane model as the initial operational limit. 
Those cost estimates would be expected to be higher than estimates 
based on LOVs that design approval holders anticipate establishing 
because in most cases, these LOVs are expected to exceed the design 
service goals. During the comment period, manufacturers provided the 
LOVs that they anticipate they will be establishing under today's rule. 
Those LOVs were 33% to 180% higher than the airplane's design service 
goal. Accordingly, our analysis in the Final Regulatory Evaluation uses 
these anticipated LOVs and indicates a lower cost to operators than was 
initially projected.
    Airbus stated that not all of its models will have LOVs from 33% to 
180% beyond the airplane's design service goal. Airbus will have LOVs 
for some models that will be equal to the airplane's design service 
goal. Although some of Airbus's LOVs are equal to the design service 
goal, which makes the LOVs span a shorter time, we still do not 
anticipate that any Airbus airplanes will need to be retired during the 
20-year analysis period as a result of this final rule.
    FedEx, Northwest Airlines, and ATA argued that operator cost 
estimates are not credible if they are based on anticipated LOVs 
instead of LOVs that have been accepted by the FAA and industry. It is 
for this reason that FedEx further argued that an operational rule must 
be proposed after the design approval holder's LOVs have been approved 
by the FAA. This would also, noted the commenter, provide the

[[Page 69773]]

public with the opportunity to comment on those LOVs.
    The FAA measures the economic loss to operators of retiring an 
airplane at LOV instead of at a planned future retirement date. The FAA 
considers that this is a reasonable way to estimate compliance costs 
and that, ultimately, the LOVs that are accepted by the FAA and 
industry will be very close to those anticipated LOVs that the FAA has 
received from industry and used for these estimates of cost.
b. Need To Know Maintenance Actions To Determine Cost
    Some commenters suggested that the costs associated with 
maintenance actions to preclude WFD prior to reaching the LOV either 
could not be determined or were substantially underestimated because 
the actions were not yet developed. Other commenters indicated that 
costs used in the regulatory evaluation do not accurately reflect 
operators' costs. They said, for example, that estimates of the number 
of hours needed to accomplish inspections, the number of inspections 
needed in a maintenance visit, and the number of days an airplane is 
out of service to accomplish maintenance did not reflect the actual 
experience of operators. Boeing added that the overall cost of the rule 
is difficult to determine because there will be costs related to 
maintenance actions required by airworthiness directives.
    Although this final rule allows design approval holders to 
establish LOVs without relying on maintenance actions, the FAA expects 
most design approval holders will adopt LOVs that rely on such actions. 
As discussed in the NPRM, design approval holders are not required to 
identify and develop maintenance actions if they can show that such 
actions are not necessary to prevent WFD before the airplanes reach the 
LOV. As discussed in the Final Regulatory Evaluation, the FAA 
anticipates that at least Boeing will propose LOVs that will depend 
upon accomplishment of future maintenance actions. This is consistent 
with Boeing's current practice of developing service information that 
defines the maintenance actions to address WFD in its products. 
However, any maintenance actions necessary to reach the LOV will be 
mandated by airworthiness directives through separate rulemaking 
actions, so their costs are not attributable to this final rule. This 
is also consistent with the current practice of issuing airworthiness 
directives to address unsafe conditions associated with WFD. The FAA 
will provide cost estimates when issuing the airworthiness directives 
for any maintenance actions necessary to prevent WFD.
    The FAA recognizes that this final rule is unusual in that it may 
depend upon future rulemaking to fully achieve its safety objectives. 
In the context of WFD, this approach is necessary to enable design 
approval holders to propose LOVs that allow operators the longest 
operational lives for their airplanes, while still ensuring freedom 
from WFD. This approach allows for an implementation strategy that 
provides flexibility to design approval holders in determining the 
timing of service information development (with FAA approval), while 
providing operators with certainty regarding the LOV applicable to 
their airplanes. The FAA has issued many airworthiness directives in 
the past to address WFD issues, and the agency anticipates that the 
approach adopted today will interface smoothly with existing practices 
for issuing airworthiness directives.
    In this regard, this final rule is similar to SFAR 88, which also 
required design approval holders to perform technical evaluations (in 
that case, of fuel tank ignition sources) and to develop necessary 
maintenance actions that would be mandated by airworthiness directive. 
To date, the FAA has issued over 100 airworthiness directives to 
address unsafe conditions identified as a result of SFAR 88. These 
airworthiness directives were issued based on this proactive approach 
of requiring analyses to identify unsafe conditions, rather than 
relying on service experience to identify them, with potentially 
catastrophic results. In the context of SFAR 88, this approach has been 
generally recognized as being effective. The objective of this final 
rule is to establish a similar proactive approach that will enable us 
to issue any necessary airworthiness directives before WFD results in 
potentially catastrophic structural failure.
c. Costs to Manufacturers
    Airbus indicated that, considering the significant number of hours 
necessary to train enough engineers and then to comply with the rule, 
the Initial Regulatory Evaluation substantially underestimated the 
costs of this rulemaking for manufacturers. Airbus said that the cost 
of future LOV extensions should be included. Based on further 
discussion to identify these costs, Airbus and the FAA agreed that 
Airbus currently meets the intent of today's rule by performing an 
evaluation of structure susceptible to fatigue and establishing an LOV 
prior to the development of WFD. The rule does not require 
manufacturers to extend LOVs--thus these extensions are not a 
compliance cost. The FAA does understand that LOV extensions are part 
of the existing Airbus business practice.
    Boeing stated that the most significant costs will be borne by the 
manufacturer rather than the operator. When the manufacturer has to 
perform additional fatigue testing to substantiate an operational 
limit, said the commenter, the costs could be quite significant. Based 
on further discussion to identify these costs, Boeing and the FAA 
agreed that, because Boeing is also already engaged in the activities 
required by this final rule, its additional costs will be minimal.
    A later Boeing comment, however, said that the regulatory 
evaluation summarized in the Technical Document, which was developed by 
the FAA for the public meeting, does not identify future expenses the 
Boeing Company will incur. Boeing believes this discounting is not 
correct because the company still has substantial work to do in 
providing maintenance programs for repairs and alterations, and in 
developing LOVs and supportive maintenance actions for post-Amendment 
25-45 airplanes. Boeing said that the costs of an airworthiness 
directive are being attributed to operators, but do not account for 
manufacturers' costs. A second point made by this commenter was that 
certain LOVs may be set at a point lower than hoped, simply because the 
maintenance actions needed to bring that LOV out to a more distant 
point may be too technically difficult and costly to perform. This 
could result in a considerable amount of engineering work for Boeing to 
develop the LOV that, because the maintenance actions are never 
released, might not result in recompense for Boeing. Boeing said that 
we are presenting costs as either voluntary compliance for setting LOVs 
or as airworthiness directive costs for developing maintenance actions.
    In discussions, Boeing has informed us that the company will 
voluntarily do this work to address WFD in its airplanes, with or 
without the rule. As a result, the rule does not impose costs, and the 
regulatory evaluation properly does not assign costs to Boeing's 
voluntary compliance. The rule does not require that design approval 
holders develop maintenance actions to be performed to support the LOV, 
nor does the rule require development of LOVs for repairs, alterations, 
and modifications. If the LOV developed by the design approval holder 
does specify maintenance actions, the FAA will separately estimate the 
costs of those

[[Page 69774]]

maintenance actions at the time as part of the airworthiness directive 
notice. Any work done on repairs, alterations, and modifications, 
because it is not required by the rule, is not accounted for as a cost 
of the rule. Compliance costs are assumed to be borne by the operators. 
If manufacturers have incurred costs in developing the maintenance 
actions for operators to reach LOV, there is nothing that precludes 
them from being recompensed for that work. The FAA based the analysis 
of costs in our Initial Regulatory Evaluation on discussions with the 
AAWG. Because this final rule is significantly different from the NPRM, 
the agency has re-evaluated these costs, and the results are reflected 
in the Final Regulatory Evaluation.
d. Cost of Failing To Harmonize Rule
    Industry representatives on the AAWG, Airbus, Boeing, and the ATA 
pointed out that the regulatory evaluation did not consider the cost of 
failing to harmonize the rule with other airworthiness authorities. 
Commenters suggested that--if the rule were not harmonized--there would 
be a substantial negative economic impact with respect to the transfer, 
lease, or sales of airplanes between the U.S. and other countries. 
Commenters suggested that bilateral agreements be amended to support 
the transfer of used airplanes subject to this final rule.
    As discussed in section III.K. above, the FAA is working closely 
with EASA and other national airworthiness authorities to harmonize 
this final rule as much as possible. Many of the changes to the 
proposed rule will facilitate such harmonization.
e. Cost To Replace an Airplane
    A number of commenters said that the initial regulatory evaluation 
used replacement costs that are not accurate or justified. According to 
the ATA, ``The assumptions used in the regulatory evaluation ignore the 
reality that some airlines replace their fleets with new aircraft in 
most cases, while others (particularly cargo carriers) depend on used 
aircraft with long remaining lives to support their particular business 
case.'' In a related vein, Airbus, the ATA, and an individual commenter 
said that the regulatory evaluation failed to consider the significant 
cost to operators of retiring airplanes. Of particular concern was the 
situation where airplanes that support an operation reach their 
operational limit, and there are no new airplanes which could fill the 
same role. The ATA said that the regulatory evaluation ignores factors 
that operators would take into account when deciding whether to retire 
an airplane or to seek approval of an extended operational limit but 
did not define those factors.
    In the public meeting on December 11, 2008, a commenter 
representing United Parcel Service noted that the cost benefit analysis 
was based only on Boeing airplanes, and said that if the Airbus 
airplanes were included, there would be one airplane model with an LOV 
that is actually less than the design service goal in the original 
NPRM. United Parcel Service commented that operators of those airplanes 
would be interested in understanding how that economic impact to the 
residual value of those airplanes was not included in the cost. United 
Parcel Service also asked, since Boeing had expressed discomfort with 
the use of the anticipated LOV information that it had originally given 
the FAA, how the FAA could be comfortable using that information for 
the regulatory evaluation. Since the public meeting, Boeing has 
provided updated information about anticipated LOVs for their 
airplanes. Airbus has provided a table containing updated information 
on certain Airbus model LOVs and anticipated extensions to LOVs. The 
FAA uses this updated information in the Final Regulatory Evaluation.
    Lynden Air Cargo said that the initial regulatory evaluation did 
not provide a true economic impact for either design approval holders 
or operators because it is based upon unknown facts from too few design 
approval holders and with no input from operators, who will bear 90% of 
the costs. Lynden Air Cargo provided flight cycle and flight hour data 
for its L-382G airplanes. Based on an LOV of 75,000 flight hours, 
Lynden Air Cargo stated that issuance of the ``anticipated LOVs,'' 
which are included in the Technical Document, would require that Lynden 
Air Cargo immediately retire three of its six airplanes and, at the 
Lynden Air Cargo current utilization rate, retire the other three by 
approximately December 2019. Lynden Air Cargo estimates the cost to 
replace its six airplanes would range from $120 million to $810 
million, if comparable airplanes were available.
    Lockheed indicated that the LOV anticipated for the L-382 would be 
based only on flight hours. Based on flight hours, usage, and current 
ownership, we do not estimate that any L-382 airplanes will be retired 
in our 20-year analysis period. Lockheed stated that it will continue 
to support the L-382 model regardless of whether the FAA issues a WFD 
rule.
    In developing the Final Regulatory Evaluation, the FAA used a 
commercial fleet data product that identifies the status of airplane 
hours and cycles. The FAA found only one U.S.-registered airplane 
currently operating under part 121 with a number of flight cycles 
exceeding the anticipated LOV for the airplane and only five U.S.-
registered airplanes operating under part 121 that exceed 80% of those 
LOVs.
    The economic cost of requiring retirement of an airplane at the 
anticipated LOV is a central issue in the cost estimate for today's 
rule. Common business practice is to value assets at the current market 
value, and the FAA follows this practice in the Final Regulatory 
Evaluation. In the case of airplanes at or near the end of their 
commercial lives, this value is quite small. Assigning a cost of 
purchasing a new airplane to replace an airplane at LOV would be a 
serious overstatement because it ignores the decline in value as 
airplanes age.
f. Residual Value of Airplanes
    Several commenters, including the ATA, FedEx, United Parcel 
Service, Airbus, the CAA, Technical Data Analysis, Inc., and Celeris 
Aerospace of Canada, stated that the initial regulatory evaluation did 
not consider the impact of the proposal on loans, leases, and residual 
value of airplanes. They said the rule would have a particularly 
significant effect on cargo operations, which tend to use older 
airplanes.
    These comments are based on an assumption that LOVs will be 
established at levels below where significant numbers of airplanes 
would otherwise be retired.
    As discussed previously, the vast majority of airplanes are 
currently retired well before the LOVs that design approval holders 
anticipate establishing under this final rule. These retirements are 
for economic reasons unrelated to today's rule. The FAA expects that 
future retirement decisions will be made for similar reasons and that 
this final rule will force retirement of only one airplane that is 
otherwise reaching the end of its commercial operational life.
    We use an appraiser-estimated airplane value when the airplane 
reaches LOV before retirement. This estimate properly reflects the true 
value of the asset. To include any other cost estimate would be double 
counting.
3. ``Rotable'' Parts
    Northwest Airlines commented that it is not clear whether or not 
airplane life limits (the commenter's term for LOVs) extend to 
components, such as engine nacelles, passenger and cargo doors, flight 
controls, and wing-to-body fairings. These components can be

[[Page 69775]]

``swapped out,'' or rotated (they're known in the industry as rotable 
parts) from one airplane to another. Northwest Airlines said that there 
is a potential for significant costs associated with rotable parts if 
they are limited by an airplane's LOV. Operators typically do not track 
the number of accumulated flight cycles or flight hours for them. 
Northwest Airlines stated that operators may have to assume the flight 
cycles or flight hours on affected rotable parts to be equal to the 
world high-time airplane for that model. This may require that 
operators ground many airplanes or scrap rotable parts, resulting in 
significant costs that have not been captured in the regulatory 
evaluation included in the Technical Document.
    The LOV is an airplane-level number. The FAA does not anticipate 
that rotable parts will be identified by design approval holders as 
structure susceptible to WFD. This is because the parts typically 
considered as rotable do not have structural details and elements that 
are repeated over large areas and operate at the same stress levels. AC 
120-YY provides examples of structure in which multiple site damage or 
multiple element damage could occur. Rotable parts are not included in 
those examples. As a result, we have determined that rotable parts do 
not affect the cost of this final rule.
4. Use of LOVs for Financial Evaluations
    Airbus expressed concerns similar to those expressed by Boeing and 
the members of AAWG about lack of uniformity in the manner in which 
various manufacturers are setting LOVs. The commenter also stated that 
it was important that the LOVs, and the LOV flight hour or flight cycle 
numbers, not be used by non-technical people in the finance community 
to set depreciation schedules, commercial valuations, comparisons, and 
competitive arguments. Airbus was concerned that such use of non-
standardized data could lead to market distortion.
    Airbus requested that we not publish LOV tables for each 
manufacturer's product lines in the rule and its preamble. It stated 
that this information would much more appropriately be published and 
updated in the manufacturer's Instructions for Continued Airworthiness 
for each airplane. Airbus suggested that, if the FAA nevertheless 
decides that publishing such LOV tables is necessary, then it would be 
important to develop, in concert with industry, the definitions, 
criteria, and methodologies to be used, so that resulting LOVs from all 
sources are consistent.
    The FAA has revised the rule to ensure that there is an objective, 
performance-based standard for developing LOVs, and AC 120-YY has been 
updated to provide guidance in complying with those standards. The 
reason that design approval holders may appear to be arriving at 
different LOV numbers is largely a function of the age of their 
respective fleets. A design approval holder whose fleet is older will 
have a much larger body of service experience on which to confidently 
base an LOV. A design approval holder with a younger fleet might be 
more conservative when first setting an LOV, because there is not as 
much service experience data on which to base it. Another factor 
affecting how a design approval holder goes about setting an LOV is how 
much fatigue testing has been performed on a particular model.
    The FAA appreciates that Airbus supports the intent of the WFD 
rulemaking, and understands Airbus' concern that LOVs could be 
misinterpreted by those who ``set or approve'' the economic life of an 
airplane. The FAA does not expect, nor intend, the LOV in the WFD final 
rule to set the economic life of an airplane. The March 18, 2009 
edition of Aviation Daily reported that Airbus has extended the service 
goals of the A330-200 and A340-200 and -300. The purpose of publishing 
manufacturers' LOVs in the regulatory evaluation appendix is to provide 
clarity, transparency, and reproducibility for the economic analysis. 
As Airbus requested, the reason for the publication of LOVs is 
clarified in the Final Regulatory Evaluation. In the regulatory 
evaluation, the FAA states that it is important to note that 
manufacturers have changed LOVs based on updated information. Airbus, 
for instance, sets an initial LOV as a declared point for certification 
purposes. Periodically, as airplanes are shown to be viable for longer 
lives, design approval holders put programs in place to extend LOVs 
well before those utilizations are achieved. The FAA believes that 
manufacturers will continue this practice into the future and update 
their airplanes' LOVs. Thus the LOVs used in this regulatory evaluation 
should not be used as a basis for setting the economic life of an 
airplane. Based upon history, our estimated costs, which were based 
upon the current LOVs, may be overstated.

IV. Regulatory Notices and Analyses

Paperwork Reduction Act

    The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires 
that the FAA consider the impact of paperwork and other information 
collection burdens imposed on the public. According to the 1995 
amendments to the Paperwork Reduction Act (5 CFR 1320.8(b)(2)(vi)), an 
agency may not collect or sponsor the collection of information, nor 
may it impose an information collection requirement, unless it displays 
a currently valid Office of Management and Budget (OMB) control number.
    This final rule will impose the following new information 
collection requirements. As required by the Paperwork Reduction Act of 
1995 (44 U.S.C. 3507(d)), the FAA has submitted these information 
collection amendments to OMB for its review. The Office of Management 
and Budget approved these new information collection requirements 
associated with this final rule and assigned OMB Control Number 2120-
0743.
    Title: Widespread Fatigue Damage.
    Summary: Today's rule consists of regulatory changes pertaining to 
widespread fatigue damage in transport category airplanes. Some of 
these changes require new information collection. The new information 
requirements and the persons required to provide that information are 
described below.
    (1) Amendment of part 26 requires that holders of design approvals 
for certain existing transport category airplanes establish limits of 
validity (operational limits) for those airplanes. Those design 
approval holders are also required to revise the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness 
(ICA) to include the LOV.
    (2) Amendment of part 26 also requires that design approval holders 
submit to the FAA a plan detailing how they intend to comply with the 
new requirements. The compliance plan ensures that design approval 
holders fully understand the requirements, correct any deficiencies in 
planning in a timely manner, and provide the information needed by the 
operators for timely compliance with the rule.
    (3) Any person operating an airplane under part 121 or 129 is 
required to revise its maintenance program to incorporate an 
Airworthiness Limitations section that includes an LOV. Operators would 
be prohibited from operating an airplane past that limit.
    (4) As an option, any person may apply for an extended LOV for 
affected airplanes. This option has requirements similar to those 
imposed on design approval holders for establishing an initial LOV. 
There may be service information developed that would

[[Page 69776]]

support the extended limit and would be documented as airworthiness 
limitation items. To operate beyond the initial LOV, an operator would 
have to incorporate the extended limit and any airworthiness limitation 
items pertaining to widespread fatigue damage into its maintenance 
program.
    Use of Collected Information: These requirements support the 
information needs of the FAA in finding compliance with the rule by 
design approval holders and operators.
    Average Annual Burden Estimate: The burden would consist of the 
work necessary to:
     Develop or revise the Airworthiness Limitations section of 
the Instructions for Continued Airworthiness to include the LOV.
     Develop the compliance plan.
     Incorporate the new information into the operator's 
maintenance program.
    Today's rule results in the following annual recordkeeping and 
reporting burden:

                               Figure 4--Recordkeeping and Reporting for This Rule
----------------------------------------------------------------------------------------------------------------
                                                                                                   Present value
  Documents required to show compliance with the proposed rule      Total labor    Total average    discounted
                                                                       hours       annual hours    ($2010) cost
----------------------------------------------------------------------------------------------------------------
FAA-approved revised or new ALS.................................             660             132         $41,674
FAA-approved WFD compliance plan................................             435           * 435          33,418
FAA-approved maintenance program revision for operators.........             210              35          12,846
                                                                 -----------------------------------------------
    Total.......................................................           1,305             602          87,938
----------------------------------------------------------------------------------------------------------------
* This one-time burden will occur in the first 90 days of the compliance period.

    The FAA computed the annual recordkeeping burden (in total hours) 
by analyzing the paperwork needed to satisfy each requirement of the 
rule. The average cost per hour varies with the number of affected 
airplanes in each group, the amount of engineering time required to 
develop the LOV, and the amount of time required for revising the 
Airworthiness Limitations section of the Instructions for Continued 
Airworthiness. Other costs associated with the information collection 
requirements within this rule (in addition to the monetized hourly 
costs reflected above) are minimal.
    In addition to the requirements outlined above, future applicants 
for either supplemental type certificates or amendments to type 
certificates that decrease or increase maximum takeoff gross weights 
would be required to develop a compliance plan for the certification 
project. The Paperwork Reduction Act compliance for development of 
these certification plans is covered by a previously approved 
collection (OMB Control Number 2120-0018) associated with part 21. We 
estimate the additional burden to include information on a plan for 
establishing an LOV for these airplanes would be minimal.

International Compatibility

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, it is FAA policy to comply with 
International Civil Aviation Organization (ICAO) Standards and 
Recommended Practices to the maximum extent practicable. The FAA has 
determined that there are no ICAO Standards and Recommended Practices 
that correspond to these regulations.

Economic Assessment, Regulatory Flexibility Determination, Trade Impact 
Assessment, and Unfunded Mandates Assessment

    This portion of the preamble summarizes the FAA's analysis of the 
economic impacts of this Final Rule. It also includes the final 
regulatory flexibility determination, the international trade impact 
assessment, and the unfunded mandates assessment. The FAA suggests 
readers seeking greater detail read the full regulatory evaluation, a 
copy of which has been placed in the docket for this rulemaking.
    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs that each Federal agency 
shall propose or adopt a regulation only upon a reasoned determination 
that the benefits of the intended regulation justify its costs. Second, 
the Regulatory Flexibility Act of 1980 requires agencies to analyze the 
economic impact of regulatory changes on small entities. Third, the 
Trade Agreements Act (19 U.S.C. 2531-2533) prohibits agencies from 
setting standards that create unnecessary obstacles to the foreign 
commerce of the United States. In developing U.S. standards, this Trade 
Act requires agencies to consider international standards and, where 
appropriate, to be the basis of U.S. standards. Fourth, the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies to 
prepare a written assessment of the costs, benefits, and other effects 
of proposed or final rules that include a Federal mandate likely to 
result in the expenditure by State, local, or Tribal governments, in 
the aggregate, or by the private sector, of $100 million or more 
annually (adjusted for inflation).
    In conducting these analyses, FAA has determined this final rule 
has benefits that justify its costs, and is a ``significant regulatory 
action'' as defined in section 3(f) of Executive Order 12866 because it 
raises novel policy issues contemplated under that executive order. The 
rule is also ``significant'' as defined in DOT's Regulatory Policies 
and Procedures. The final rule, if adopted, however, will not have a 
significant economic impact on a substantial number of small entities, 
will not create unnecessary obstacles to international trade and will 
not impose an unfunded mandate on State, local, or Tribal governments, 
or on the private sector. These analyses, available in the docket, are 
summarized below.

Total Costs and Benefits of This Rulemaking

    The overriding safety concern of today's rule is WFD-related 
incidents and accidents that have occurred and the continuing 
discoveries of WFD problems in the fleet. The current approach does not 
always find WFD before in-flight events occur. Today's rule will 
establish the necessary steps to prevent WFD in the future by requiring 
that design approval holders establish LOVs.
    With this final rule, design approval holders may continue their 
work to provide maintenance actions that support the safe operation of 
airplanes up to LOV. The FAA would proactively issue airworthiness 
directives mandating those planned maintenance actions rather than 
reactively issuing emergency airworthiness directives and immediately 
adopted rules which

[[Page 69777]]

require unanticipated inspections and repairs. The FAA estimates that 
this approach is worth $4.8 million in present value.
    In contrast to the NPRM, the final rule total costs are minor. 
Several significant factors are responsible for the reduction in these 
costs. First, the final rule does not include the repair, alterations, 
and modification requirement as in the NPRM. Second, many older 
airplanes have been retired since the NPRM. Third, due to the comments 
and conversations with design approval holders, the agency now 
understands that most LOVs will be set 33% to 180% higher than design 
service goal rather than at design service goal as was specified in the 
NPRM. Because of current maintenance programs and voluntary compliance 
by design approval holders, costs for design approval holders and 
operators are expected to be minimal. We anticipate that today's rule 
will result in one airplane retiring sooner than the operator would 
like, in contrast to the NPRM which predicted that many airplanes would 
retire sooner. Thus our base case model attributes the cost of this 
rule to the retirement of that one airplane, because it will reach the 
anticipated LOV within the 20-year analysis period. This will result in 
costs of $3.8 million, with a present value of $3.6 million.
    Thus, as noted earlier, this final rule's expected present-value 
benefits of $4.8 million exceed the expected present-value costs of 
$3.6 million.

                        Figure 5--Comparison of Cost Assumptions for NPRM and Final Rule
----------------------------------------------------------------------------------------------------------------
                                                                                                    Final rule
                                             NPRM present                                         present  value
             NPRM assumptions               value costs ($         Final rule assumptions            costs  ($
                                               millions)                                             millions)
----------------------------------------------------------------------------------------------------------------
Operator Retirement Costs.................             160  Operator Retirement Costs...........             3.6
     Initial Operational Limit                         Limit of validity (LOV) >
     (IOL) = Design Service Goal (DSG).                     DSG for many models
     27 airplanes would be retired                     1 airplane would be
     in the first year of compliance.                       retired in the 20[dash]year analysis
                                                            period
     Some IOL extensions.                              Few LOV extensions
Operator Maintenance Program Costs........             164  Operator Maintenance Program Costs..               0
     WFD maintenance actions \49\                    With higher LOV, WFD
     were included with extended                             maintenance actions may be
     operational limits.                                     necessary and would be mandated by
                                                             ADs, per existing practice.\50\
     We assumed some operators                         Operators' costs to
     would perform maintenance actions.                     perform maintenance actions are
                                                            included in cost of ADs
Design Approval Holder (DAH) Costs........              36  DAH Costs...........................               0
    Assumed 10% of entire costs.                              Assumed minimal costs because DAHs
                                                            are voluntarily developing LOVs and
                                                            maintenance actions
                                           ----------------                                      ---------------
        Total Costs.......................             360    Total Costs.......................             3.6
----------------------------------------------------------------------------------------------------------------

Who is potentially affected by this rulemaking?

     Design approval holders of transport category airplanes 
with a maximum takeoff gross weight greater than 75,000 pounds.
---------------------------------------------------------------------------

    \49\ Maintenance actions include inspections, modifications, and 
replacements. Because the extended LOV is not required, operators 
would have to decide to retire airplanes or perform the maintenance 
actions with the extended LOV.
    \50\ These ADs would be issued eventually, even without this 
rule, because WFD is inevitable and is an unsafe condition. More ADs 
may need to be written without this rule. If the necessary service 
information is not developed until after a finding of WFD in 
service, the resulting ADs are likely to include interim action 
requirements and have shorter compliance times, as compared with ADs 
issued based on service information developed as required by this 
rule.
---------------------------------------------------------------------------

     Applicants for type certificates of transport category 
airplanes with a maximum takeoff gross weight greater than 75,000 
pounds, if the date of application was before the effective date of the 
rule.
     Applicants for amendments to type certificates of 
transport category airplanes with a maximum takeoff gross weight 
greater than 75,000 pounds, with the exception of those that change the 
maximum takeoff gross weight of the airplane.
     Applicants or design approval holders for either 
supplemental type certificates or amendments to type certificates that 
increase maximum takeoff gross weights from 75,000 pounds or less to 
greater than 75,000 pounds.
     Applicants or design approval holders for either 
supplemental type certificates or amendments to type certificates that 
decrease maximum takeoff gross weight from greater than 75,000 pounds 
to 75,000 pounds or less after the effective date of the rule.
     Applicants for future type certificates, or for either 
supplemental type certificates or amendments to future type 
certificates, for all transport category airplanes, after the effective 
date of the rule.
     U.S. certificate holders and foreign air carriers and 
foreign persons operating U.S.-registered transport category airplanes 
under 14 CFR part 121 or 129 with a maximum takeoff gross weight 
greater than 75,000 pounds.
     Operators of any transport category airplanes certified in 
the future, regardless of maximum takeoff gross weight, if the date of 
application was after the effective date of the rule.

Our Cost Assumptions and Sources of Information

     Discount rate = 7%.
     Period of Analysis = 20 years.
     Value of fatality averted = $5.8 million (Source: U.S. 
Department of Transportation, Treatment of Value of Life and Injuries 
in Preparing Economic Evaluations, February 8, 2008).
     Aircraft Values = 2009 Avitas Blue Book of Jet Aircraft/
Industry Consultation.
     Aircraft Fleet Data = OAG Associates Fleet Database.

Alternatives Considered

    The FAA considered four alternatives to the proposed rule. These 
were:
    1. Exclude small entities.
    2. Extend the compliance deadline for small entities.

[[Page 69778]]

    3. Establish lesser technical requirements for small entities.
    4. Expand the requirements To cover more airplanes.
1. Exclude Small Entities
    The FAA concluded that excluding small entities from all the 
requirements of the proposed rule was not justified. The purpose of the 
proposed rule is to maintain the airworthy operating condition of 
airplanes regardless of secondary considerations.
2. Extend the Compliance Deadline for Small Entities
    The FAA also considered options that would lengthen the compliance 
period for small operators. The FAA believes time extensions only 
provide modest cost savings and leave the system safety at risk.
3. Establish Lesser Technical Requirements for Small Entities
    The FAA considered establishing lesser technical requirements for 
small entities. However, the FAA believes the risks are similarly 
unreasonable for small entities operating airplanes susceptible to WFD, 
and that the benefits of including small entities justify the cost.
4. Expand the Requirements To Cover More Airplanes
    The FAA considered requiring all operators of existing transport 
category airplanes to comply with the proposed rule. However, the 
overwhelming majority of passengers and cargo are carried by airplanes 
with a maximum gross takeoff weight of greater than 75,000 pounds. The 
75,000 pound weight cutoff was based on recommendations from the AAWG 
for WFD rulemaking. Because of this, the FAA decided to restrict 
compliance to operators of those airplanes.
    The FAA concludes the current rule is the preferred alternative 
because it has benefits exceeding compliance costs and allows for 
continued operation of certain airplanes only up to the point where 
existing maintenance actions can no longer ensure that the airplanes 
are free from WFD.

Benefits of This Rulemaking

    The non-quantified benefits include the safe (from WFD) operation 
of airplanes up to the LOV.
    The lower-bound present value benefits of this final rule (the 
minimum value of a range estimate of benefits) are $4.8 million in 
present value. These quantified benefits are based on the near 
elimination of emergency airworthiness directives.

Costs of This Rulemaking

    The total incremental costs of this final rule are approximately 
$3.6 million in present value from the costs of retiring one airplane.

Final Regulatory Flexibility Analysis

Introduction and Purpose of This Analysis
    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) 
establishes ``as a principle of regulatory issuance that agencies shall 
endeavor, consistent with the objectives of the rule and of applicable 
statutes, to fit regulatory and informational requirements to the scale 
of the businesses, organizations, and governmental jurisdictions 
subject to regulation. To achieve this principle, agencies are required 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions to assure that such proposals are given 
serious consideration.'' The RFA covers a wide range of small entities, 
including small businesses, not-for-profit organizations, and small 
governmental jurisdictions.
    Agencies must perform a review to determine whether a rule will 
have a significant economic impact on a substantial number of small 
entities. If the agency determines that it will, the agency must 
prepare a regulatory flexibility analysis as described in the RFA.
    However, if an agency determines that a rule is not expected to 
have a significant economic impact on a substantial number of small 
entities, section 605(b) of the RFA provides that the head of the 
agency may so certify and a regulatory flexibility analysis is not 
required. The certification must include a statement providing the 
factual basis for this determination, and the reasoning should be 
clear.
    The FAA considers that this final rule will not result in a 
significant economic impact on a substantial number of small entities. 
The purpose of this analysis is to provide the reasoning underlying the 
FAA determination.
    First, we will discuss the reasons why the FAA is considering this 
action. We will follow with a discussion of the objective of, and legal 
basis for, the final rule. Next, we explain there are no relevant 
Federal rules which may overlap, duplicate, or conflict with the final 
rule. Then we will discuss the substantial changes from the proposed to 
the final rule. Next, we will discuss the comments received about the 
Initial Regulatory Flexibility Analysis (IRFA). Lastly, we will 
describe and provide an estimate of the number of small entities 
affected by the final rule and why the FAA considers that this final 
rule will not result in a significant economic impact on a substantial 
number of small entities.
    We now discuss the reasons why the FAA is considering this action.
    The FAA is issuing this final rule to address the structural 
problems of aging airplanes known as ``widespread fatigue damage'' 
(WFD). WFD is characterized by the simultaneous presence of cracks at 
multiple structural locations that are of sufficient size and density 
that the structure will no longer meet its residual strength 
requirement and could catastrophically fail.
    Past examples of WFD occurring in the fleet include:
     The 1988 Aloha 737 accident,
     An in-flight Lockheed Model L-1011 failure of aft pressure 
bulkhead stringer attach fittings,
     A McDonnell Douglas Model DC-9 aft pressure bulkhead 
cracks,
     Boeing Models 727 and 737 lap splice cracking,
     Boeing Model 767 aft pressure bulkhead cracking, and
     Boeing Model 747 and Airbus A300 frame cracking.
    Because of these past incidents, accidents, and inspection 
discoveries and others, the FAA has already issued about 100 WFD-
related airworthiness directives.
    This final rule is being promulgated because the FAA believes the 
risk of an accident caused by WFD, and the potential collateral damage 
after such an accident, is too high without implementing today's rule.
    We now discuss the objective of, and legal basis for, the final 
rule. Next, we discuss if there are relevant Federal rules which may 
overlap, duplicate, or conflict with the final rule.
    Title 49 of the United States Code requires the FAA Administrator 
to consider the following authority:
     Assigning, maintaining, and enhancing safety and security 
as the highest priorities in air commerce. (49 U.S.C. 40101(d)(1).
     Aging Airplane Safety Act of 1991. (49 U.S.C. 44717).
     The FAA Administrator's statutory duty to carry out his or 
her responsibilities ``in a way that best tends to reduce or eliminate 
the possibility or recurrence of accidents in air transportation.'' 
(See 49 U.S.C. 44701(c)).
    Therefore, this final rule will amend Title 14 of the Code of 
Federal Regulations to require existing design approval holders to 
establish LOVs and operators of any affected airplane to incorporate 
those LOVs into maintenance programs of large transport

[[Page 69779]]

category airplanes with a maximum takeoff gross weight greater than 
75,000 pounds, operating under 14 CFR part 121 and 129. These 
requirements will also apply to all applicants for type certificates 
after the effective date of the rule and operators of those airplanes. 
Today's rule does not require that any maintenance actions be performed 
to prevent WFD before an airplane reaches its LOV. Any maintenance 
actions necessary to reach the LOV will be mandated by airworthiness 
directives through separate rulemaking actions, so their costs are not 
attributable to this final rule.
    This final rule will not overlap, duplicate, or conflict with 
existing Federal Rules.
    We now discuss the changes from the proposed to the final rule and 
the reason the small entity determination in the Final Regulatory 
Flexibility Analysis (FRFA) has changed.
    The FAA has made substantial changes to the WFD NPRM that 
significantly reduces costs to both small and large business entities. 
We have eliminated the requirement to evaluate WFD associated with 
repairs, alterations, and modifications of the baseline airplane 
structure, except for those mandated by airworthiness directives. This 
change dramatically reduces the economic impact of the NPRM's estimated 
compliance costs to small entity operators of part 25 airplanes. Also, 
in our request for comments, design approval holders responded by 
providing estimates of LOVs for their affected airplanes. In the NPRM 
we assumed the LOV will occur at an airplane's design service goal. 
Based on design approval holder comments LOV, in many cases, occurs 
anywhere from 33% to 180% beyond the design service goal, depending on 
the equipment model. An operator can now operate an airplane well past 
its design service goal and not incur the costs of making the decision 
to retire or extend the affected airplane's LOV until much later in the 
airplane's life. The only remaining cost is that we assume operators 
will retire their airplanes at LOV, rather than incurring the cost of 
the additional maintenance actions that may be needed for an extended 
LOV. With the scope of the rule reduced, both in terms of required 
inspections and in terms of affected airplanes, the economic costs of 
this final rule are much lower than the costs estimated in the NPRM and 
in the initial regulatory evaluation.
    The FAA will now discuss the one comment received about the Initial 
Regulatory Flexibility Analysis (IRFA).
    In the responses to the IRFA of the NPRM, we received a comment 
from Lynden Air Cargo. Lynden stated its L-382G airplanes were not 
included in IRFA. The commenter is correct. The Fleet data services 
consulted for the initial regulatory evaluation did not carry flight 
utilization data for L-382Gs, and the FAA was unable to determine the 
number of accumulated flight cycles or flight hours of Lynden's fleet 
in comparison to the anticipated LOV for those airplanes. Because of 
the lack of utilization data, Lynden's fleet was not included in our 
sample for the IRFA analysis. Lynden Air Cargo has since provided the 
FAA with utilization information for its L-382G fleet. Lockheed has 
provided an updated anticipated LOV for the L-382G fleet, based just in 
hours, and Lynden's entire fleet is below 80% of the LOV. With the base 
hours less than 80% of LOV, and with the current utilization rates of 
these airplanes, they will not reach LOV in the 20-year analysis time 
frame. Therefore the FAA expects no economic impact to Lynden Air Cargo 
in the analysis period for the final rule.
    The FAA will now discuss the methodology used to determine the 
number of small entities for which the final rule will apply. The FAA 
will also discuss why the agency considers that this final rule will 
not result in a significant economic impact on manufacturers of part 25 
airplanes.
    For aircraft operators and manufacturers, a small entity is defined 
as one with 1,500 or fewer employees.\51\ Since there are operators 
that met those criteria, the FAA conducted an economic impact 
assessment to determine if the rule will have a significant economic 
impact on a substantial number of these operators.
---------------------------------------------------------------------------

    \51\ 13 CFR 121.201, Size Standards Used to Define Small 
Business Concerns, Sector 48-49 Transportation, Subsector 481 Air 
Transportation.
---------------------------------------------------------------------------

    This final rule will become fully effective in 2010. Although the 
FAA forecasts traffic and air carrier fleets to 2030, too many factors 
are in play to estimate a future number of small entities, determine if 
an operator will still be in business, or determine whether that 
operator will still remain a small business entity. Therefore the 
agency will use the current U.S. operator's fleet and employment in 
order to determine the number and impact on small business entities 
this final rule will affect.
    For analysis purposes, the FAA has divided the small entities that 
might be impacted by this final rule into two major classes, airplane 
manufacturers and air carriers.
    Currently, U.S. part 25 aircraft manufacturer type certificate 
holders include the following:
     The Boeing Company.
     Cessna Aircraft Company (a subsidiary of Textron Inc.).
     Raytheon Company.
     Gulfstream Aerospace Corporation (a wholly owned 
subsidiary of General Dynamics).
    All United States part 25 aircraft manufacturers exceed the Small 
Business Administration small-entity criteria of 1,500 employees for 
aircraft manufacturers.
    Air carriers potentially affected by the final rule include 
operators engaged in the following:
     Scheduled air transportation.
     Air courier service.
     Nonscheduled air transportation.
    The FAA obtained the number of U.S.-operated airplanes having a 
maximum takeoff gross weight greater than 75,000 pounds from the OAG 
Associates Fleet Database (March 2009). This database identifies U.S. 
operators of affected airplanes by providing airplane age and flight 
utilization statistics. The FAA used the airplane flight utilization 
information in the analysis of small entity operator's airplanes 
affected by this WFD final rule. The FAA obtained annual operators' 
revenue and employment data from current public filings, the World 
Aviation Directory, and U.S. DOT Form 41 schedules.
    Companies with greater than 1,500 employees were excluded from 
further analysis. Operators in Chapter XI bankruptcy were also 
excluded, since the outcomes of such proceedings are unknown. Lastly, 
we excluded all part 25 turbine-powered airplanes with a maximum 
takeoff gross weight of 75,000 pounds or less, or with a type 
certificate issued before January 1, 1958, because these airplanes are 
not affected by the final rule.
    This procedure resulted in a list of airplanes, operated by U.S. 
operators with less than 1,500 employees, with a gross takeoff weight 
greater than 75,000 pounds. To this database were added airplane-
specific design service goals, LOVs, and airplane residual value 
fields. The FAA used the design service goals published in the WFD NPRM 
and later updated them based on FAA and industry input. Manufacturers 
provided the LOVs. Airplane residual values were obtained from the 2009 
Avitas Bluebook of Jet Aircraft and consultations with industry.
    Next follows the discussion of the number of small entity operators 
with airplanes affected by the rule, and how

[[Page 69780]]

much it will cost for them to be in compliance.
    Today's rule may cause airplanes to be retired, sold, or replaced 
sooner than an operator would like. Companies make decisions on the 
retirement, sale, or replacement of airplanes for many reasons. The 
decision point to sell, retire, or replace an airplane differs across 
companies. Operators take into account several key factors in their 
decision on when to retire an aircraft. The following are some of those 
key factors:
     Maintenance costs.
     Noise levels.
     Fuel consumption.
     Loss of consumer demand.
     Regulation changes.
     Shifting operator business plans.
     Operating costs.
    Therefore, a company generally decides to retire, sell, or replace 
an airplane long before its LOV is reached. Given current airplane 
utilization rates, the FAA does not expect the final rule to affect 
companies below 75% of an airplane's LOV. When an airplane's flight 
utilization (measured in flight cycles or hours) exceeds 75% of LOV, 
the expectation is that the WFD provisions will become an increasingly 
important component of the decision to retire the airplane. All U.S. 
airplanes over 75% LOV currently operated by small business entities 
are in non-scheduled service. Many of these affected airplanes are 
being operated by cargo operators and hence have a lower utilization 
rate than their counterparts in scheduled passenger service.
    The FAA discovered that 21 airplanes being operated by eight small 
entities were over 75% of LOV. For the 21 affected airplanes over 75% 
of LOV, the FAA analyzed utilization history reports by serial number. 
Results of this analysis showed that saying that 21 airplanes are over 
75% of their LOVs overstates the number of airplanes affected by this 
final rule, because some of those airplanes listed as active have not 
accrued utilization statistics for years. The agency has identified 9 
out of the 21 affected airplanes that have not accrued utilization for 
the past two years or longer. If the airplanes are not accumulating 
flight cycles or hours for years, then given the age of these 
airplanes, the FAA assumes that these airplanes are parked or retired.
    This final rule will impose either the retirement of an airplane at 
LOV or a set of maintenance changes to extend the LOV for the airplane. 
In this final regulatory analysis, the assumption is that operators 
will retire the airplanes at LOV. The airplane retirement cost is the 
operator's most expensive economic choice based on compliance with the 
final rule.
    The FAA's analysis determined that no small entities currently 
operate airplanes over 100% of LOV.
    One small entity currently operates one airplane between 90-100% of 
LOV. Four small entities currently operate four airplanes between 80-
90% of LOV. Lastly, the database lists four small entities operating 
seven airplanes between 75-80% of LOV. Table 1 shows these results:
[GRAPHIC] [TIFF OMITTED] TR15NO10.000

    To estimate when an airplane will exceed LOV, the FAA followed 
these steps: From the March 2009 OAG Associates Fleet database the FAA 
calculated the average age of U.S.-operated part 25 transport category 
retired airplanes over time. OAG defines a retired airplane as one that 
has been retired, scrapped or otherwise destroyed by its owner/operator 
at the end of the airplane's useful life. The FAA calculated the 
average age based upon the retired airplanes in the OAG fleet database 
beginning in the 1940s. On average, part 25 passenger airplanes were 
operated for 25 years and cargo airplanes were operated for 34 years, 
and then retired from U.S. service.
    For the base case in the regulatory evaluation, the FAA assumed 
that in year 25 of operation, every affected passenger airplane will 
convert to cargo service and then retire from cargo service at 34 
years. The FAA chose this scenario for the cost model because it 
captures nearly all of the affected airplanes.
    The FAA applied these average ages to the affected airplanes in 
Table 1 and retired airplanes over the average retirement age of 34 
years over the 20-year analysis interval used in the regulatory 
evaluation. Under this model, the agency assumes retirement of only one 
Boeing 747 airplane operated by a small business entity, because that 
airplane will reach its LOV before reaching its average retirement age.
    The model estimates one small business entity will retire one 
airplane soon after the rule is promulgated. This small business entity 
will need to implement an appropriate WFD program, and either apply for 
an extended LOV or retire the airplane. For the FRFA, the FAA assumed 
the affected small entity will retire the airplane.
    The FAA estimated the final rule's present value costs to the air 
carrier based on the 2009 Avitas Bluebook of Jet Aircraft residual 
value of the airplane forced to retire. The present-value residual 
value of the affected airplane is $3.6 million. The ratio of this 
present value cost to annual revenues is 1.28%. The FAA does not 
consider this impact to be economically significant, and since only one 
entity is potentially affected, this is not a substantial number of 
small entities.
    The FAA Administrator certifies that this rule will not have a 
significant economic impact on a substantial number of small entities.

International Trade Impact Analysis

    The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the 
Uruguay Round Agreements Act (Pub. L. 103-465), prohibits Federal 
agencies from establishing standards or engaging

[[Page 69781]]

in related activities that create unnecessary obstacles to the foreign 
commerce of the United States. Pursuant to these Acts, the 
establishment of standards is not considered an unnecessary obstacle to 
the foreign commerce of the United States, so long as the standard has 
a legitimate domestic objective, such as the protection of safety, and 
does not operate in a manner that excludes imports that meet this 
objective. The statute also requires consideration of international 
standards and, where appropriate, that they be the basis for United 
States standards. The FAA has assessed the potential effect of this 
final rule and determined that it will impose the same costs on 
domestic and international entities and thus has a neutral trade 
impact.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement 
assessing the effects of any Federal mandate in a proposed or final 
agency rule that may result in an expenditure of $100 million or more 
(in 1995 dollars) in any one year by State, local, and Tribal 
governments, in the aggregate, or by the private sector; such a mandate 
is deemed to be a ``significant regulatory action.'' The FAA currently 
uses an inflation-adjusted value of $136.1 million in lieu of $100 
million. This final rule does not contain such a mandate. The 
requirements of Title II do not apply.

Executive Order 13132, Federalism

    The FAA has analyzed this final rule under the principles and 
criteria of Executive Order 13132, Federalism. We determined that this 
action will not have a substantial direct effect on the States, the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government. Therefore, today's rule does not have federalism 
implications.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the FAA, when modifying its regulations in a manner 
affecting intrastate aviation in Alaska, to consider the extent to 
which Alaska is not served by transportation modes other than aviation, 
and to establish appropriate regulatory distinctions. In the NPRM, the 
FAA requested comments on whether the proposed rule should apply 
differently to intrastate operations in Alaska. As discussed earlier, 
the FAA received comments on this subject from the late Senator 
Stevens, Senator Murkowski, and Everts Air Cargo and has determined 
that there would not be an adverse effect on intrastate air 
transportation in Alaska and that regulatory distinctions are not 
appropriate.

Environmental Analysis

    FAA Order 1050.1E identifies FAA actions that are categorically 
excluded from preparation of an environmental assessment or 
environmental impact statement under the National Environmental Policy 
Act in the absence of extraordinary circumstances. The FAA has 
determined this rulemaking action qualifies for the categorical 
exclusion identified in paragraph 312f of the order and involves no 
extraordinary circumstances.

Regulations That Significantly Affect Energy Supply, Distribution, or 
Use

    The FAA has analyzed this rule under Executive Order 13211, Actions 
Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). We have determined that it is not 
a ``significant regulatory action'' under the executive order because, 
while it is a ``significant regulatory action'' under Executive Order 
12866 and DOT's Regulatory Policies and Procedures, it is not likely to 
have a significant adverse effect on the supply, distribution, or use 
of energy.

List of Subjects

14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements, Continued airworthiness.

14 CFR Part 26

    Aircraft, Aviation safety, Continued airworthiness.

14 CFR Parts 121 and 129

    Air carriers, Aircraft, Aviation safety, Continued airworthiness, 
Reporting and recordkeeping requirements.

The Amendments

0
In consideration of the foregoing, the Federal Aviation Administration 
amends Chapter I of Title 14, Code of Federal Regulations, parts 25, 
26, 121, and 129, as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

0
1. The authority citation for part 25 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702 and 44704.

0
2. Amend Sec.  25.571 by revising paragraphs (a)(3) introductory text 
and (b) introductory text to read as follows:

Sec.  25.571  Damage-tolerance and fatigue evaluation of structure.

    (a) * * *
    (3) Based on the evaluations required by this section, inspections 
or other procedures must be established, as necessary, to prevent 
catastrophic failure, and must be included in the Airworthiness 
Limitations section of the Instructions for Continued Airworthiness 
required by Sec.  25.1529. The limit of validity of the engineering 
data that supports the structural maintenance program (hereafter 
referred to as LOV), stated as a number of total accumulated flight 
cycles or flight hours or both, established by this section must also 
be included in the Airworthiness Limitations section of the 
Instructions for Continued Airworthiness required by Sec.  25.1529. 
Inspection thresholds for the following types of structure must be 
established based on crack growth analyses and/or tests, assuming the 
structure contains an initial flaw of the maximum probable size that 
could exist as a result of manufacturing or service-induced damage:
* * * * *
    (b) Damage-tolerance evaluation. The evaluation must include a 
determination of the probable locations and modes of damage due to 
fatigue, corrosion, or accidental damage. Repeated load and static 
analyses supported by test evidence and (if available) service 
experience must also be incorporated in the evaluation. Special 
consideration for widespread fatigue damage must be included where the 
design is such that this type of damage could occur. An LOV must be 
established that corresponds to the period of time, stated as a number 
of total accumulated flight cycles or flight hours or both, during 
which it is demonstrated that widespread fatigue damage will not occur 
in the airplane structure. This demonstration must be by full-scale 
fatigue test evidence. The type certificate may be issued prior to 
completion of full-scale fatigue testing, provided the Administrator 
has approved a plan for completing the required tests. In that case, 
the Airworthiness Limitations section of the Instructions for Continued 
Airworthiness required by Sec.  25.1529 must specify that no airplane 
may be operated beyond a number of cycles equal to \1/2\ the number of 
cycles accumulated on the fatigue test article,

[[Page 69782]]

until such testing is completed. The extent of damage for residual 
strength evaluation at any time within the operational life of the 
airplane must be consistent with the initial detectability and 
subsequent growth under repeated loads. The residual strength 
evaluation must show that the remaining structure is able to withstand 
loads (considered as static ultimate loads) corresponding to the 
following conditions:
* * * * *

0
3. Amend section H25.4 of Appendix H to part 25 by revising paragraph 
(a)(1) and adding paragraph (a)(4) to read as follows:

Appendix H to Part 25--Instructions for Continued Airworthiness

* * * * *
H25.4 Airworthiness Limitations section.

    (a) * * *
    (1) Each mandatory modification time, replacement time, 
structural inspection interval, and related structural inspection 
procedure approved under Sec.  25.571.
* * * * *
    (4) A limit of validity of the engineering data that supports 
the structural maintenance program (LOV), stated as a total number 
of accumulated flight cycles or flight hours or both, approved under 
Sec.  25.571. Until the full-scale fatigue testing is completed and 
the FAA has approved the LOV, the number of cycles accumulated by 
the airplane cannot be greater than \1/2\ the number of cycles 
accumulated on the fatigue test article.
* * * * *

PART 26--CONTINUED AIRWORTHINESS AND SAFETY IMPROVEMENTS FOR 
TRANSPORT CATEGORY AIRPLANES

0
4. The authority citation for part 26 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702 and 44704.

0
5. Revise Sec.  26.5 to read as follows:

Sec.  26.5  Applicability table.

    Table 1 of this section provides an overview of the applicability 
of this part. It provides guidance in identifying what sections apply 
to various types of entities. The specific applicability of each 
subpart and section is specified in the regulatory text.

                                     Table 1--Applicability of Part 26 Rules
----------------------------------------------------------------------------------------------------------------
                                                              Applicable sections
                             -----------------------------------------------------------------------------------
                                                    Subpart C      Subpart D fuel
                              Subpart B EAPAS/     widespread           tank         Subpart E damage  tolerance
                                     FTS         fatigue damage     flammability                data
----------------------------------------------------------------------------------------------------------------
Effective date of rule......  December 10,      January 14, 2011  December 26,      January 11, 2008
                               2007.                               2008.
Existing \1\ TC Holders.....  26.11...........  26.21...........  26.33...........  26.43, 26.45, 26.49
Pending \1\ TC Applicants...  26.11...........  26.21...........  26.37...........  26.43, 26.45
Future \2\ TC applicants....  N/A.............  N/A.............  N/A.............  26.43
Existing \1\ STC Holders....  N/A.............  26.21...........  26.35...........  26.47, 26.49
Pending \1\ STC/ATC           26.11...........  26.21...........  26.35...........  26.45, 26.47, 26.49
 applicants.
Future \2\ STC/ATC            26.11...........  26.21...........  26.35...........  26.45, 26.47, 26.49
 applicants.
Manufacturers...............  N/A.............  N/A.............  26.39...........  N/A
----------------------------------------------------------------------------------------------------------------
\1\ As of the effective date of the identified rule.
\2\ Application made after the effective date of the identified rule.

0
6. Add subpart C to read as follows:
Subpart C--Aging Airplane Safety--Widespread Fatigue Damage
Sec.
26.21 Limit of validity.
26.23 Extended limit of validity.

Subpart C--Aging Airplane Safety--Widespread Fatigue Damage

Sec.  26.21  Limit of validity.

    (a) Applicability. Except as provided in paragraph (g) of this 
section, this section applies to transport category, turbine-powered 
airplanes with a maximum takeoff gross weight greater than 75,000 
pounds and a type certificate issued after January 1, 1958, regardless 
of whether the maximum takeoff gross weight is a result of an original 
type certificate or a later design change. This section also applies to 
transport category, turbine-powered airplanes with a type certificate 
issued after January 1, 1958, if a design change approval for which 
application is made after January 14, 2011 has the effect of reducing 
the maximum takeoff gross weight from greater than 75,000 pounds to 
75,000 pounds or less.
    (b) Limit of validity. Each person identified in paragraph (c) of 
this section must comply with the following requirements:
    (1) Establish a limit of validity of the engineering data that 
supports the structural maintenance program (hereafter referred to as 
LOV) that corresponds to the period of time, stated as a number of 
total accumulated flight cycles or flight hours or both, during which 
it is demonstrated that widespread fatigue damage will not occur in the 
airplane. This demonstration must include an evaluation of airplane 
structural configurations and be supported by test evidence and 
analysis at a minimum and, if available, service experience, or service 
experience and teardown inspection results, of high-time airplanes of 
similar structural design, accounting for differences in operating 
conditions and procedures. The airplane structural configurations to be 
evaluated include--
    (i) All model variations and derivatives approved under the type 
certificate; and
    (ii) All structural modifications to and replacements for the 
airplane structural configurations specified in paragraph (b)(1)(i) of 
this section, mandated by airworthiness directives as of January 14, 
2011.
    (2) If the LOV depends on performance of maintenance actions for 
which service information has not been mandated by airworthiness 
directive as of January 14, 2011, submit the following to the FAA 
Oversight Office:
    (i) For those maintenance actions for which service information has 
been issued as of the applicable compliance date specified in paragraph 
(c) of this section, a list identifying each of those actions.
    (ii) For those maintenance actions for which service information 
has not been issued as of the applicable compliance date specified in 
paragraph (c) of this section, a list identifying each of those actions 
and a binding schedule for providing in a timely manner the necessary 
service information for those actions. Once the FAA Oversight Office 
approves this schedule, each person identified in paragraph (c) of this 
section must comply with that schedule.

[[Page 69783]]

    (3) Unless previously accomplished, establish an Airworthiness 
Limitations section (ALS) for each airplane structural configuration 
evaluated under paragraph (b)(1) of this section.
    (4) Incorporate the applicable LOV established under paragraph 
(b)(1) of this section into the ALS for each airplane structural 
configuration evaluated under paragraph (b)(1) and submit it to the FAA 
Oversight Office for approval.
    (c) Persons who must comply and compliance dates. The following 
persons must comply with the requirements of paragraph (b) of this 
section by the specified date.
    (1) Holders of type certificates (TC) of airplane models identified 
in Table 1 of this section: No later than the applicable date 
identified in Table 1 of this section.
    (2) Applicants for TCs, if the date of application was before 
January 14, 2011: No later than the latest of the following dates:
    (i) January 14, 2016;
    (ii) The date the certificate is issued; or
    (iii) The date specified in the plan approved under Sec.  25.571(b) 
for completion of the full-scale fatigue testing and demonstrating that 
widespread fatigue damage will not occur in the airplane structure.
    (3) Applicants for amendments to TCs, with the exception of 
amendments to TCs specified in paragraphs (c)(6) or (c)(7) of this 
section, if the original TC was issued before January 14, 2011: No 
later than the latest of the following dates:
    (i) January 14, 2016;
    (ii) The date the amended certificate is issued; or
    (iii) The date specified in the plan approved under Sec.  25.571(b) 
for completion of the full-scale fatigue testing and demonstrating that 
widespread fatigue damage will not occur in the airplane structure.
    (4) Applicants for amendments to TCs, with the exception of 
amendments to TCs specified in paragraphs (c)(6) or (c)(7) of this 
section, if the application for the original TC was made before January 
14, 2011 but the TC was not issued before January 14, 2011: No later 
than the latest of the following dates:
    (i) January 14, 2016;
    (ii) The date the amended certificate is issued; or
    (iii) The date specified in the plan approved under Sec.  25.571(b) 
for completion of the full-scale fatigue testing and demonstrating that 
widespread fatigue damage will not occur in the airplane structure.
    (5) Holders of either supplemental type certificates (STCs) or 
amendments to TCs that increase maximum takeoff gross weights from 
75,000 pounds or less to greater than 75,000 pounds: No later than July 
14, 2012.
    (6) Applicants for either STCs or amendments to TCs that increase 
maximum takeoff gross weights from 75,000 pounds or less to greater 
than 75,000 pounds: No later than the latest of the following dates:
    (i) July 14, 2012;
    (ii) The date the certificate is issued; or
    (iii) The date specified in the plan approved under Sec.  25.571(b) 
for completion of the full-scale fatigue testing and demonstrating that 
widespread fatigue damage will not occur in the airplane structure.
    (7) Applicants for either STCs or amendments to TCs that decrease 
maximum takeoff gross weights from greater than 75,000 pounds to 75,000 
pounds or less, if the date of application was after January 14, 2011: 
No later than the latest of the following dates:
    (i) July 14, 2012;
    (ii) The date the certificate is issued; or
    (iii) The date specified in the plan approved under Sec.  25.571(b) 
for completion of the full-scale fatigue testing and demonstrating that 
widespread fatigue damage will not occur in the airplane structure.
    (d) Compliance plan. Each person identified in paragraph (e) of 
this section must submit a compliance plan consisting of the following:
    (1) A proposed project schedule, identifying all major milestones, 
for meeting the compliance dates specified in paragraph (c) of this 
section.
    (2) A proposed means of compliance with paragraphs (b)(1) through 
(b)(4) of this section.
    (3) A proposal for submitting a draft of all compliance items 
required by paragraph (b) of this section for review by the FAA 
Oversight Office not less than 60 days before the compliance date 
specified in paragraph (c) of this section, as applicable.
    (4) A proposal for how the LOV will be distributed.
    (e) Compliance dates for compliance plans. The following persons 
must submit the compliance plan described in paragraph (d) of this 
section to the FAA Oversight Office by the specified date.
    (1) Holders of type certificates: No later than April 14, 2011.
    (2) Applicants for TCs and amendments to TCs, with the exception of 
amendments to TCs specified in paragraphs (e)(4), (e)(5), or (e)(6) of 
this section, if the date of application was before January 14, 2011 
but the TC or TC amendment was not issued before January 14, 2011: No 
later than April 14, 2011.
    (3) Holders of either supplemental type certificates or amendments 
to TCs that increase maximum takeoff gross weights from 75,000 pounds 
or less to greater than 75,000 pounds: No later than April 14, 2011.
    (4) Applicants for either STCs or amendments to TCs that increase 
maximum takeoff gross weights from 75,000 pounds or less to greater 
than 75,000 pounds, if the date of application was before January 14, 
2011: No later than April 14, 2011.
    (5) Applicants for either STCs or amendments to TCs that increase 
maximum takeoff gross weights from 75,000 pounds or less to greater 
than 75,000 pounds, if the date of application is on or after January 
14, 2011: Within 90 days after the date of application.
    (6) Applicants for either STCs or amendments to TCs that decrease 
maximum takeoff gross weights from greater than 75,000 pounds to 75,000 
pounds or less, if the date of application is on or after January 14, 
2011: Within 90 days after the date of application.
    (f) Compliance plan implementation. Each affected person must 
implement the compliance plan as approved in compliance with paragraph 
(d) of this section.
    (g) Exceptions. This section does not apply to the following 
airplane models:
    (1) Bombardier BD-700.
    (2) Bombardier CL-44.
    (3) Gulfstream GV.
    (4) Gulfstream GV-SP.
    (5) British Aerospace, Aircraft Group, and Societe Nationale 
Industrielle Aerospatiale Concorde Type 1.
    (6) British Aerospace (Commercial Aircraft) Ltd., Armstrong 
Whitworth Argosy A.W. 650 Series 101.
    (7) British Aerospace Airbus, Ltd., BAC 1-11.
    (8) BAE Systems (Operations) Ltd., BAe 146.
    (9) BAE Systems (Operations) Ltd., Avro 146.
    (10) Lockheed 300-50A01 (USAF C141A).
    (11) Boeing 707.
    (12) Boeing 720.
    (13) deHavilland D.H. 106 Comet 4C.
    (14) Ilyushin Aviation IL-96T.
    (15) Bristol Aircraft Britannia 305.
    (16) Avions Marcel Dassault-Breguet Aviation Mercure 100C.
    (17) Airbus Caravelle.
    (18) D & R Nevada, LLC, Convair Model 22.
    (19) D & R Nevada, LLC, Convair Model 23M.

[[Page 69784]]

            Table 1--Compliance Dates for Affected Airplanes
------------------------------------------------------------------------
                                                      Compliance date--
     Airplane model  (all existing \1\ models)          (months after
                                                      January 14, 2011)
------------------------------------------------------------------------
Airbus:
    A300 Series, A310 Series, A300-600 Series.....                    18
    A318 Series...................................                    48
    A319 Series...................................                    48
    A320 Series...................................                    48
    A321 Series...................................                    48
    A330-200, -200 Freighter, -300 Series.........                    48
    A340-200, -300, -500, -600 Series.............                    48
    A380-800 Series...............................                    60
Boeing:
    717...........................................                    48
    727 (all series)..............................                    18
    737 (Classics): 737-100, -200, -200C, -300, -                     18
     400, -500....................................
    737 (NG): 737-600, -700, -700C, -800, -900, -                     48
     900ER........................................
    747 (Classics): 747-100, -100B, -100B SUD, -                      18
     200B, [dash]200C, -200F, -300, 747SP, 747SR..
    747-400: 747-400, -400D, -400F................                    48
    757...........................................                    48
    767...........................................                    48
    777-200, -300.................................                    48
    777-200LR, 777-300ER, 777F....................                    60
Bombardier:
    CL-600: 2D15 (Regional Jet Series 705), 2D24                      60
     (Regional Jet Series 900)....................
Embraer:
    ERJ 170.......................................                    60
    ERJ 190.......................................                    60
Fokker:
    F.28 Mark 0070, Mark 0100.....................                    18
Lockheed:
    L-1011........................................                    18
    188...........................................                    18
    382 (all series)..............................                    18
McDonnell Douglas:
    DC-8, -8F.....................................                    18
    DC-9..........................................                    18
    MD-80 (DC-9-81, -82, -83, -87, MD-88).........                    18
    MD-90.........................................                    48
    DC-10.........................................                    18
    MD-10.........................................                    48
    MD-11, -11F...................................                    48
All Other Airplane Models Listed on a Type                            60
 Certificate as of January 14, 2011...............
------------------------------------------------------------------------
\1\ Type certificated as of January 14, 2011.

Sec.  26.23  Extended limit of validity.

    (a) Applicability. Any person may apply to extend a limit of 
validity of the engineering data that supports the structural 
maintenance program (hereafter referred to as LOV) approved under Sec.  
25.571 of this subchapter, Sec.  26.21, or this section. Extending an 
LOV is a major design change. The applicant must comply with the 
relevant provisions of subparts D or E of part 21 of this subchapter 
and paragraph (b) of this section.
    (b) Extended limit of validity. Each person applying for an 
extended LOV must comply with the following requirements:
    (1) Establish an extended LOV that corresponds to the period of 
time, stated as a number of total accumulated flight cycles or flight 
hours or both, during which it is demonstrated that widespread fatigue 
damage will not occur in the airplane. This demonstration must include 
an evaluation of airplane structural configurations and be supported by 
test evidence and analysis at a minimum and, if available, service 
experience, or service experience and teardown inspection results, of 
high-time airplanes of similar structural design, accounting for 
differences in operating conditions and procedures. The airplane 
structural configurations to be evaluated include--
    (i) All model variations and derivatives approved under the type 
certificate for which approval for an extension is sought; and
    (ii) All structural modifications to and replacements for the 
airplane structural configurations specified in paragraph (b)(1)(i) of 
this section, mandated by airworthiness directive, up to the date of 
approval of the extended LOV.
    (2) Establish a revision or supplement, as applicable, to the 
Airworthiness Limitations section (ALS) of the Instructions for 
Continued Airworthiness required by Sec.  25.1529 of this subchapter, 
and submit it to the FAA Oversight Office for approval. The revised ALS 
or supplement to the ALS must include the applicable extended LOV 
established under paragraph (b)(1) of this section.
    (3) Develop the maintenance actions determined by the WFD 
evaluation performed in paragraph (b)(1) of this section to be 
necessary to preclude WFD from occurring before the airplane reaches 
the proposed extended LOV. These maintenance actions must be documented 
as airworthiness limitation items in the ALS and submitted to the FAA 
Oversight Office for approval.

[[Page 69785]]

PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL 
OPERATIONS

0
7. The authority citation for part 121 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 40119, 41706, 44101, 44701-
44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-
44904, 44912, 45101-45105, 46105, 46301.

0
8. Add new Sec.  121.1115 to read as follows:

Sec.  121.1115  Limit of validity.

    (a) Applicability. This section applies to certificate holders 
operating any transport category, turbine-powered airplane with a 
maximum takeoff gross weight greater than 75,000 pounds and a type 
certificate issued after January 1, 1958, regardless of whether the 
maximum takeoff gross weight is a result of an original type 
certificate or a later design change. This section also applies to 
certificate holders operating any transport category, turbine-powered 
airplane with a type certificate issued after January 1, 1958, 
regardless of the maximum takeoff gross weight, for which a limit of 
validity of the engineering data that supports the structural 
maintenance program (hereafter referred to as LOV) is required in 
accordance with Sec.  25.571 or Sec.  26.21 of this chapter after 
January 14, 2011.
    (b) Limit of validity. No certificate holder may operate an 
airplane identified in paragraph (a) of this section after the 
applicable date identified in Table 1 of this section unless an 
Airworthiness Limitations section approved under Appendix H to part 25 
or Sec.  26.21 of this chapter is incorporated into its maintenance 
program. The ALS must--
    (1) Include an LOV approved under Sec.  25.571 or Sec.  26.21 of 
this chapter, as applicable, except as provided in paragraph (f) of 
this section; and
    (2) Be clearly distinguishable within its maintenance program.
    (c) Operation of airplanes excluded from Sec.  26.21. No 
certificate holder may operate an airplane identified in Sec.  26.21(g) 
of this chapter after July 14, 2013, unless an Airworthiness 
Limitations section approved under Appendix H to part 25 or Sec.  26.21 
of this chapter is incorporated into its maintenance program. The ALS 
must--
    (1) Include an LOV approved under Sec.  25.571 or Sec.  26.21 of 
this chapter, as applicable, except as provided in paragraph (f) of 
this section; and
    (2) Be clearly distinguishable within its maintenance program.
    (d) Extended limit of validity. No certificate holder may operate 
an airplane beyond the LOV, or extended LOV, specified in paragraph 
(b)(1), (c), (d), or (f) of this section, as applicable, unless the 
following conditions are met:
    (1) An ALS must be incorporated into its maintenance program that--
    (i) Includes an extended LOV and any widespread fatigue damage 
airworthiness limitation items approved under Sec.  26.23 of this 
chapter; and
    (ii) Is approved under Sec.  26.23 of this chapter.
    (2) The extended LOV and the airworthiness limitation items 
pertaining to widespread fatigue damage must be clearly distinguishable 
within its maintenance program.
    (e) Principal Maintenance Inspector approval. Certificate holders 
must submit the maintenance program revisions required by paragraphs 
(b), (c), and (d) of this section to the Principal Maintenance 
Inspector for review and approval.
    (f) Exception. For any airplane for which an LOV has not been 
approved as of the applicable compliance date specified in paragraph 
(c) or Table 1 of this section, instead of including an approved LOV in 
the ALS, an operator must include the applicable default LOV specified 
in Table 1 or Table 2 of this section, as applicable, in the ALS.

                                   Table 1--Airplanes Subject to Sec.   26.21
----------------------------------------------------------------------------------------------------------------
                                                    Compliance date--
                 Airplane model                   months after January     Default LOV [flight cycles (FC)  or
                                                        14, 2011                    flight hours (FH)]
----------------------------------------------------------------------------------------------------------------
Airbus--Existing\1\ Models Only:
    A300 B2-1A, B2-1C, B2K-3C, B2-203..........  30....................  48,000 FC
    A300 B4-2C, B4-103.........................  30....................  40,000 FC
    A300 B4-203................................  30....................  34,00 FC
    A300-600 Series............................  30....................  30,000 FC/67,500 FH
    A310-200 Series............................  30....................  40,000 FC/60,000 FH
    A310-300 Series............................  30....................  35,000 FC/60,000 FH
    A318 Series................................  60....................  48,000 FC/60,000 FH
    A319 Series................................  60....................  48,000 FC/60,000 FH
    A320-100 Series............................  60....................  48,000 FC/48,000 FH
    A320-200 Series............................  60....................  48,000 FC/60,000 FH
    A321 Series................................  60....................  48,000 FC/60,000 FH
    A330-200, -300 Series (except WV050 family)  60....................  40,000 FC/60,000 FH
     (non enhanced).
    A330-200, -300 Series WV050 family           60....................  33,000 FC/100,000 FH
     (enhanced).
    A330-200 Freighter Series..................  60....................  See NOTE.
    A340-200, -300 Series (except WV 027 and     60....................  20,000 FC/80,000 FH
     WV050 family) (non enhanced).
    A340-200, -300 Series WV 027 (non enhanced)  60....................  30,000 FC/60,000 FH
    A340-300 Series WV050 family (enhanced)....  60....................  20,000 FC/100,000 FH
    A340-500, -600 Series......................  60....................  16,600 FC/100,000 FH
    A380-800 Series............................  72....................  See NOTE.
Boeing--Existing\1\ Models Only:
    717........................................  60....................  60,000 FC/60,000 FH
    727 (all series)...........................  30....................  60,000 FC
    737 (Classics): 737-100, -200, -200C, -300,  30....................  75,000 FC
     -400, -500.
    737 (NG): 737-600, -700, -700C, -800, -900,  60....................  75,000 FC
     -900ER.
    747 (Classics): 747-100, -100B, -100B SUD, - 30....................  20,000 FC
     200B, -200C, -200F, -300, 747SP, 747SR.
    747-400: 747-400, -400D, -400F.............  60....................  20,000 FC
    757........................................  60....................  50,000 FC
    767........................................  60....................  50,000 FC
    777-200, -300..............................  60....................  40,000 FC

[[Page 69786]]

 
    777-200LR, 777-300ER.......................  72....................  40,000 FC
    777F.......................................  72....................  11,000 FC
Bombardier--Existing\1\ Models Only:
    CL-600: 2D15 (Regional Jet Series 705),      72....................  60,000 FC
     2D24 (Regional Jet Series 900).
Embraer--Existing\1\ Models Only:
    ERJ 170....................................  72....................  See NOTE.
    ERJ 190....................................  72....................  See NOTE.
Fokker--Existing\1\ Models Only:
    F.28 Mark 0070, Mark 0100..................  30....................  90,000 FC
Lockheed--Existing\1\ Models Only:
    L-1011.....................................  30....................  36,000 FC
    188........................................  30....................  26,600 FC
    382 (all series)...........................  30....................  20,000 FC/50,000 FH
McDonnell Douglas--Existing\1\ Models Only:
    DC-8, -8F..................................  30....................  50,000 FC/50,000 FH
    DC-9 (except for MD-80 models).............  30....................  100,000 FC/100,000 FH
    MD-80 (DC-9-81, -82, -83, -87, MD-88)......  30....................  50,000 FC/50,000 FH
    MD-90......................................  60....................  60,000 FC/90,000 FH
    DC-10-10, -15..............................  30....................  42,000 FC/60,000 FH
    DC-10-30, -40, -10F, -30F, -40F............  30....................  30,000 FC/60,000 FH
    MD-10-10F..................................  60....................  42,000 FC/60,000 FH
    MD-10-30F..................................  60....................  30,000 FC/60,000 FH
    MD-11, MD-11F..............................  60....................  20,000 FC/60,000 FH
Maximum Takeoff Gross Weight Changes:
    All airplanes whose maximum takeoff gross    30, or within 12        Not applicable.
     weight has been decreased to 75,000 pounds   months after the LOV
     or below after January 14, 2011 or           is approved, or
     increased to greater than 75,000 pounds at   before operating the
     any time by an amended type certificate or   airplane, whichever
     supplemental type certificate.               occurs latest.
All Other Airplane Models (TCs and amended TCs)  72, or within 12        Not applicable.
 not Listed in Table 2.                           months after the LOV
                                                  is approved, or
                                                  before operating the
                                                  airplane, whichever
                                                  occurs latest.
----------------------------------------------------------------------------------------------------------------
\1\ Type certificated as of January 14, 2011.

    Note: Airplane operation limitation is stated in the 
Airworthiness Limitation section.

                                  Table 2--Airplanes Excluded from Sec.   26.21
----------------------------------------------------------------------------------------------------------------
                                                                     Default LOV  [flight cycles (FC)  or flight
                          Airplane model                                             hours (FH)]
----------------------------------------------------------------------------------------------------------------
Airbus:
    Caravelle.....................................................  15,000 FC/24,000 FH
Avions Marcel Dassault:
    Breguet Aviation Mercure 100C.................................  20,000 FC/16,000 FH
Boeing:
    Boeing 707 (-100 Series and -200 Series)......................  20,000 FC
    Boeing 707 (-300 Series and -400 Series)......................  20,000 FC
    Boeing 720....................................................  30,000 FC
Bombardier:
    CL-44D4 and CL-44J............................................  20,000 FC
    BD-700........................................................  15,000 FH
Bristol Aeroplane Company:
    Britannia 305.................................................  10,000 FC
British Aerospace Airbus, Ltd.:
    BAC 1-11 (all models).........................................  85,000 FC
British Aerospace (Commercial Aircraft) Ltd.:
    Armstrong Whitworth Argosy A.W. 650 Series 101................  20,000 FC
BAE Systems (Operations) Ltd.:
    BAe 146-100A (all models).....................................  50,000 FC
    BAe 146-200-07................................................  50,000 FC
    BAe 146-200-07 Dev............................................  50,000 FC
    BAe 146-200-11................................................  50,000 FC
    BAe 146-200-07A...............................................  47,000 FC
    BAe 146-200-11 Dev............................................  43,000 FC

[[Page 69787]]

 
    BAe 146-300 (all models)......................................  40,000 FC
    Avro 146-RJ70A (all models)...................................  40,000 FC
    Avro 146-RJ85A and 146-RJ100A (all models)....................  50,000 FC
D & R Nevada, LLC:
    Convair Model 22..............................................  1,000 FC/1,000 FH
    Convair Model 23M.............................................  1,000 FC/1,000 FH
deHavilland Aircraft Company, Ltd.:
    D.H. 106 Comet 4C.............................................  8,000 FH
Gulfstream:
    GV............................................................  40,000 FH
    GV-SP.........................................................  40,000 FH
Ilyushin Aviation Complex:
    IL-96T........................................................  10,000 FC/30,000 FH
Lockheed:
    300-50A01 (USAF C 141A).......................................  20,000 FC
----------------------------------------------------------------------------------------------------------------

PART 129--OPERATIONS: FOREIGN AIR CARRIERS AND FOREIGN OPERATORS OF 
U.S.-REGISTERED AIRCRAFT ENGAGED IN COMMON CARRIAGE

0
9. The authority citation for part 129 continues to read:

    Authority: 49 U.S.C. 1372, 40113, 40119, 44101, 44701-44702, 
44705, 44709-44711, 44713, 44716-44717, 44722, 44901-44904, 44906, 
44912, 46105, Pub. L. 107-71 sec. 104.

0
10. Add new Sec.  129.115 to read as follows:

Sec.  129.115  Limit of validity.

    (a) Applicability. This section applies to foreign air carriers or 
foreign persons operating any U.S.-registered transport category, 
turbine-powered airplane with a maximum takeoff gross weight greater 
than 75,000 pounds and a type certificate issued after January 1, 1958, 
regardless of whether the maximum takeoff gross weight is a result of 
an original type certificate or a later design change. This section 
also applies to foreign air carriers or foreign persons operating any 
other U.S.-registered transport category, turbine-powered airplane with 
a type certificate issued after January 1, 1958, regardless of the 
maximum takeoff gross weight, for which a limit of validity of the 
engineering data that supports the structural maintenance program 
(hereafter referred to as LOV) is required in accordance with Sec.  
25.571 or Sec.  26.21 of this chapter after January 14, 2011.
    (b) Limit of validity. No foreign air carrier or foreign person may 
operate a U.S.-registered airplane identified in paragraph (a) of this 
section after the applicable date identified in Table 1 of this 
section, unless an Airworthiness Limitations section (ALS) approved 
under Appendix H to part 25 or Sec.  26.21 of this chapter is 
incorporated into its maintenance program. The ALS must--
    (1) Include an LOV approved under Sec.  25.571 or Sec.  26.21 of 
this chapter, as applicable, except as provided in paragraph (f) of 
this section; and
    (2) Be clearly distinguishable within its maintenance program.
    (c) Operation of airplanes excluded from Sec.  26.21. No 
certificate holder may operate an airplane identified in Sec.  26.21(g) 
of this chapter after July 14, 2013, unless an ALS approved under 
Appendix H to part 25 or Sec.  26.21 of this chapter is incorporated 
into its maintenance program. The ALS must--
    (1) Include an LOV approved under Sec.  25.571 or Sec.  26.21 of 
this chapter, as applicable, except as provided in paragraph (f) of 
this section; and
    (2) Be clearly distinguishable within its maintenance program
    (d) Extended limit of validity. No foreign air carrier or foreign 
person may operate an airplane beyond the LOV or extended LOV specified 
in paragraph (b)(1), (c), (d), or (f) of this section, as applicable, 
unless the following conditions are met:
    (1) An ALS must be incorporated into its maintenance program that--
    (i) Includes an extended LOV and any widespread fatigue damage 
airworthiness limitation items (ALIs) approved under Sec.  26.23 of 
this chapter; and
    (ii) Is approved under Sec.  26.23 of this chapter;
    (2) The extended LOV and the airworthiness limitation items 
pertaining to widespread fatigue damage must be clearly distinguishable 
within its maintenance program.
    (e) Principal Maintenance Inspector approval. Foreign air carriers 
or foreign persons must submit the maintenance program revisions 
required by paragraphs (b), (c), and (d) of this section to the 
Principal Maintenance Inspector or Flight Standards International Field 
Office for review and approval.
    (f) Exception. For any airplane for which an LOV has not been 
approved as of the applicable compliance date specified in paragraph 
(c) or Table 1 of this section, instead of including an approved LOV in 
the ALS, an operator must include the applicable default LOV specified 
in Table 1 or Table 2 of this section, as applicable, in the ALS.

                                   Table 1--Airplanes Subject to Sec.   26.21
----------------------------------------------------------------------------------------------------------------
                                                    Compliance date--
                 Airplane model                   months after January     Default LOV [flight  cycles (FC) or
                                                        14, 2011                    flight hours (FH)]
----------------------------------------------------------------------------------------------------------------
Airbus--Existing \1\ Models Only:
    A300 B2-1A, B2-1C, B2K-3C, B2-203..........  30....................  48,000 FC
    A300 B4-2C, B4-103.........................  30....................  40,000 FC
    A300 B4-203................................  30....................  34,000 FC
    A300-600 Series............................  30....................  30,000 FC/67,500 FH

[[Page 69788]]

 
    A310-200 Series............................  30....................  40,000 FC/60,000 FH
    A310-300 Series............................  30....................  35,000 FC/60,000 FH
    A318 Series................................  60....................  48,000 FC/60,000 FH
    A319 Series................................  60....................  48,000 FC/60,000 FH
    A320-100 Series............................  60....................  48,000 FC/48,000 FH
    A320-200 Series............................  60....................  48,000 FC/60,000 FH
    A321 Series................................  60....................  48,000 FC/60,000 FH
    A330-200, -300 Series (except WV050 family)  60....................  40,000 FC/60,000 FH
     (non enhanced).
    A330-200, -300 Series WV050 family           60....................  33,000 FC/100,000 FH
     (enhanced).
    A330-200 Freighter Series..................  60....................  See NOTE.
    A340-200, -300 Series (except WV 027 and     60....................  20,000 FC/80,000 FH
     WV050 family) (non enhanced).
    A340-200, -300 Series WV 027 (non enhanced)  60....................  30,000 FC/60,000 FH
    A340-300 Series WV050 family (enhanced)....  60....................  20,000 FC/100,000 FH
    A340-500, -600 Series......................  60....................  16,600 FC/100,000 FH
    A380-800 Series............................  72....................  See NOTE.
Boeing--Existing \1\ Models Only:
    717........................................  60....................  60,000 FC/60,000 FH
    727 (all series)...........................  30....................  60,000 FC
    737 (Classics): 737-100, -200, -200C, -300,  30....................  75,000 FC
     -400, -500.
    737 (NG): 737-600, -700, -700C, -800, -900,  60....................  75,000 FC
     -900ER.
    747 (Classics): 747-100, -100B, -100B SUD, - 30....................  20,000 FC
     200B, -200C, -200F, -300, 747SP, 747SR.
    747-400: 747-400, -400D, -400F.............  60....................  20,000 FC
    757........................................  60....................  50,000 FC
    767........................................  60....................  50,000 FC
    777-200, -300..............................  60....................  40,000 FC
    777-200LR, 777-300ER.......................  72....................  40,000 FC
    777F.......................................  72....................  11,000 FC
Bombardier--Existing \1\ Models Only:
    CL-600: 2D15 (Regional Jet Series 705),      72....................  60,000 FC
     2D24 (Regional Jet Series 900).
Embraer--Existing \1\ Models Only:
    ERJ 170....................................  72....................  See NOTE.
    ERJ 190....................................  72....................  See NOTE.
Fokker--Existing \1\ Models Only:
    F.28 Mark 0070, Mark 0100..................  30....................  90,000 FC
Lockheed--Existing \1\ Models Only:
    L-1011.....................................  30....................  36,000 FC
    188........................................  30....................  26,600 FC
    382 (all series)...........................  30....................  20,000 FC/50,000 FH
McDonnell Douglas--Existing \1\ Models Only:
    DC-8, -8F..................................  30....................  50,000 FC/50,000 FH
    DC-9 (except for MD-80 series).............  30....................  100,000 FC/100,000 FH
    MD-80 (DC-9-81, -82, -83, -87, MD-88)......  30....................  50,000 FC/50,000 FH
    MD-90......................................  60....................  60,000 FC/90,000 FH
    DC-10-10, -15..............................  30....................  42,000 FC/60,000 FH
    DC-10-30, -40, -10F, -30F, -40F............  30....................  30,000 FC/60,000 FH
    MD-10-10F..................................  60....................  42,000 FC/60,000 FH
    MD-10-30F..................................  60....................  30,000 FC/60,000 FH
    MD-11, MD-11F..............................  60....................  20,000 FC/60,000 FH
Maximum Takeoff Gross Weight Changes...........  30, or within 12        Not applicable.
                                                  months after the LOV
                                                  is approved, or
                                                  before operating the
                                                  airplane, whichever
                                                  occurs latest.
All airplanes whose maximum takeoff gross
 weight has been decreased to 75,000 pounds or
 below after January 14, 2011 or increased to
 greater than 75,000 pounds at any time by an
 amended type certificate or supplemental type
 certificate.
All Other Airplane Models (TCs and amended TCs)  72, or within 12        Not applicable.
 not Listed in Table 2.                           months after the LOV
                                                  is approved, or
                                                  before operating the
                                                  airplane, whichever
                                                  occurs latest.
----------------------------------------------------------------------------------------------------------------
\1\ Type certificated as of January 14, 2011.

    Note: Airplane operation limitation is stated in the 
Airworthiness Limitation section.

[[Page 69789]]

                                  Table 2--Airplanes Excluded from Sec.   26.21
----------------------------------------------------------------------------------------------------------------
                                                                     Default LOV [flight  cycles (FC) or flight
                          Airplane model                                             hours (FH)]
----------------------------------------------------------------------------------------------------------------
Airbus:
    Caravelle.....................................................  15,000 FC/24,000 FH
Avions Marcel Dassault:
    Breguet Aviation Mercure 100C.................................  20,000 FC/16,000 FH
Boeing:
    Boeing 707 (-100 Series and -200 Series)......................  20,000 FC
    Boeing 707 (-300 Series and -400 Series)......................  20,000 FC
    Boeing 720....................................................  30,000 FC
Bombardier:
    CL-44D4 and CL-44J............................................  20,000 FC
    BD-700........................................................  15,000 FH
Bristol Aeroplane Company:
    Britannia 305.................................................  10,000 FC
British Aerospace Airbus, Ltd.:
    BAC 1-11 (all models).........................................  85,000 FC
British Aerospace (Commercial Aircraft) Ltd.:
    Armstrong Whitworth Argosy A.W. 650 Series 101................  20,000 FC
BAE Systems (Operations) Ltd.:
    BAe 146-100A (all models).....................................  50,000 FC
    BAe 146-200-07................................................  50,000 FC
    BAe 146-200-07 Dev............................................  50,000 FC
    BAe 146-200-11................................................  50,000 FC
    BAe 146-200-07A...............................................  47,000 FC
    BAe 146-200-11 Dev............................................  43,000 FC
    BAe 146-300 (all models)......................................  40,000 FC
    Avro 146-RJ70A (all models)...................................  40,000 FC
    Avro 146-RJ85A and 146-RJ100A (all models)....................  50,000 FC
D & R Nevada, LLC:
    Convair Model 22..............................................  1,000 FC/1,000 FH
    Convair Model 23M.............................................  1,000 FC/1,000 FH
deHavilland Aircraft Company, Ltd.:
    D.H. 106 Comet 4C.............................................  8,000 FH
Gulfstream:
    GV............................................................  40,000 FH
    GV-SP.........................................................  40,000 FH
Ilyushin Aviation Complex:
    IL-96T........................................................  10,000 FC/30,000 FH
Lockheed:
    300-50A01 (USAF C 141A).......................................  20,000 FC
----------------------------------------------------------------------------------------------------------------

    Issued in Washington, DC, on October 28, 2010.
J. Randolph Babbitt,
Administrator.
[FR Doc. 2010-28363 Filed 11-12-10; 8:45 am]
BILLING CODE 4910-13-P