[Federal Register Volume 71, Number 74 (Tuesday, April 18, 2006)]
[Proposed Rules]
[Pages 19928-19951]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3621]



[[Page 19927]]

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Part II





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 25, 121, and 129



Aging Aircraft Program: Widespread Fatigue Damage; Proposed Rule

  Federal Register / Vol. 71, No. 74 / Tuesday, April 18, 2006 / 
Proposed Rules  

[[Page 19928]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 25, 121, and 129

[Docket No. FAA-2006-24281; Notice No. 06-04]
RIN 2120-AIO5


Aging Aircraft Program: Widespread Fatigue Damage

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking.

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SUMMARY: This action is intended to prevent widespread fatigue damage 
by proposing to require that design approval holders establish 
operational limits on transport category airplanes. Design approval 
holders would also be required to determine if maintenance actions are 
needed to prevent widespread fatigue damage before an airplane reaches 
its operational limit. Operators of any affected airplane would be 
required to incorporate the operational limit and any necessary service 
information into their maintenance programs. Operation of an affected 
airplane beyond the operational limit would be prohibited, unless an 
operator has incorporated an extended operational limit and any 
necessary service information into its maintenance program.

DATES: Send your comments on or before July 17, 2006.

ADDRESSES: You may send comments [identified by Docket Number FAA-2006-
24281] using any of the following methods:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001. Due to the suspension of paper mail delivery 
to DOT headquarters facilities, we encourage commenters to send their 
comments electronically.
     Fax: 1-202-493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For more information on the rulemaking process, see the 
SUPPLEMENTARY INFORMATION section of this document.
    Privacy: We will post all comments we receive, without change, to 
http://dms.dot.gov, including any personal information you provide. For 
more information, see the Privacy Act discussion in the SUPPLEMENTARY 
INFORMATION section of this document.
    Docket: To read background documents or comments received, go to 
http://dms.dot.gov at any time or to Room PL-401 on the plaza level of 
the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Walter Sippel, FAA, Transport Airplane 
Airframe/Cabin Safety Branch, ANM-115, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue, SW., Renton, WA 
98039-4056; telephone (425) 227-2774, fax (425) 227-1232.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. We also 
invite comments relating to the economic, environmental, energy, or 
federalism impacts that might result from adopting the proposals in 
this document. The most helpful comments reference a specific portion 
of the proposal, explain the reason for any recommended change, and 
include supporting data. We ask that you send us two copies of written 
comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning this proposed rulemaking. The docket is available for public 
inspection before and after the comment closing date. If you wish to 
review the docket in person, go to the address in the ADDRESSES section 
of this preamble between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. You may also review the docket using the 
Internet at the web address in the ADDRESSES section.
    Privacy Act: Using the search function of our docket Web site, 
anyone can find and read the comments received into any of our dockets, 
including the name of the individual sending the comment (or signing 
the comment on behalf of an association, business, labor union, etc.). 
You may review DOT's complete Privacy Act statement in the Federal 
Register published on April 11, 2000 (65 FR 19477-78) or you may visit 
http://dms.dot.gov.
    Before acting on this proposal, we will consider all comments we 
receive on or before the closing date for comments. We will consider 
comments filed late if it is possible to do so without incurring 
expense or delay. We may change this proposal in light of the comments 
we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a preaddressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it to you.

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (http://dms.dot.gov/search).
    (2) Visiting the Office of Rulemaking's Web page at http://www.faa.gov/avr/arm/nprm.cfm?nav=nprm; or
    (3) Accessing the Government Printing Office's Web page at http://www.access.gpo.gov/su_docs/aces/aces140.html.
    You can also get a copy by sending a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue, SW., Washington, DC 20591, or by calling (202) 267-9680. Make 
sure to identify the docket number, notice number, or amendment number 
of this rulemaking.

I. Executive Summary

    The rule proposed today would establish operational limits for 
transport category airplanes to preclude widespread fatigue damage 
(WFD). It would also require actions to prevent WFD in repairs, 
alterations, and modifications \1\ to these airplanes. This proposal 
should preclude WFD from occurring in transport category airplanes by 
providing a more proactive management of WFD.
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    \1\ Throughout this proposal, reference is made to 
``alterations'' and ``modifications.'' We consider these terms to be 
synonymous. An ``alteration'' is a design change that is made to an 
airplane; however, various segments of industry have also defined 
these changes as ``modifications.'' Therefore, we use both terms in 
the proposed rule to be all inclusive of any design change and to 
avoid potential misinterpretation of the intent of these terms.
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    This proposal would require type certificate (TC) holders to 
establish an initial operational limit on certain airplanes. Operation 
of these airplanes beyond the initial operational limit would be 
prohibited, unless operators have incorporated an extended operational 
limit into their maintenance programs. Type certificate holders would 
be required to develop the initial

[[Page 19929]]

operational limits based on an evaluation of WFD susceptibility, both 
for existing airplanes and for proposed future certifications. For 
future type certification, all TC applicants for transport category 
airplanes would be affected. For existing type certificates, this 
proposal would affect only airplanes with maximum takeoff gross weights 
(MTGW) over 75,000 pounds, including airplanes that have had the MTGW 
increased to greater than 75,000 pounds. (These airplanes are referred 
to in this document as large transport category airplanes.) 
Supplemental type certificate (STC) holders for these airplanes would 
be required to evaluate their STCs for WFD and the ability of the 
airplane to remain free of WFD up to the initial operational limit 
established by the TC holder.
    Once the proposed initial operational limits are developed, then 
operational rules in parts 121 and 129 would require operators to 
incorporate initial operational limits into their maintenance programs. 
The proposed operational rules would prohibit operation beyond the 
limit established for an airplane. However, the proposed design 
approval holder and operational rules would provide means for any 
person to extend the initial operational limit and for operators to 
operate an airplane under the extended operational limit. If an 
extended operational limit is incorporated, the proposed operational 
rules would prohibit operation beyond the extended operational limit 
established for an airplane. In addition, the proposed operational 
rules would address repairs, alterations, and modifications to 
airplanes operating with an extended operational limit.
    The present value benefits of this proposal consist of $726 million 
of accident prevention benefits and $83 million of detection benefits 
for total benefits of $809 million. The detection benefits are the 
benefits resulting from averted accidents and a reduction in 
unscheduled maintenance and repairs. The present value cost of this 
proposal, estimated over 20 years, is $360 million. The FAA estimates 
that airplane manufacturers would incur approximately 10 percent of 
these costs, while the remaining 90 percent of these costs would be 
borne by operators.

II. Background

A. Widespread Fatigue Damage

    WFD is the simultaneous presence of cracks at multiple structural 
locations that are of sufficient size and density such that the 
structure will no longer meet the residual strength requirements of 
section 25.571(b). Fatigue damage is the gradual deterioration of a 
material subjected to repeated loads. Airplane structure experiences 
fatigue damage because it is subjected to repeated loads, such as the 
pressurization and depressurization of an airplane that occurs with 
each flight. The fatigue damage could result in cracks occurring in 
structure over time.
    The likelihood of WFD in airplane structure increases with use. WFD 
results from many cracks that are generally too small to be reliably 
detected using existing inspection methods. These cracks could grow 
together very rapidly, so that failure could occur before another 
inspection is performed to detect them. The simultaneous presence of 
fatigue cracks that may grow together, with or without other damage in 
the same structural element, such as a large skin panel, is known as 
multiple site damage. The simultaneous presence of fatigue cracks in 
similar adjacent structural elements, such as frames and stringers, is 
known as multiple element damage. Some structural elements can be 
susceptible to both types of damage, which potentially could occur at 
the same time. If undetected, either type of damage could lead to 
catastrophic failure due to reduction of the strength capability of the 
structure.
    The FAA, the European Joint Aviation Authorities, and 
representatives of the Airworthiness Assurance Working Group, working 
under the support of the Aviation Rulemaking Advisory Committee (ARAC), 
reviewed available service difficulty reports for the transport 
airplane fleet. They also evaluated the certification and design 
practices applied to these previously certificated airplanes, including 
fatigue test results. The review revealed that all airplanes in the 
fleet are susceptible to multiple site damage or multiple element 
damage. Table 1 identifies examples of structures susceptible to 
multiple site damage (MSD) and multiple element damage (MED).

   Table 1.--Examples of Structures Susceptible to Widespread Fatigue
                                 Damage
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                 Structure                         Susceptible to
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Longitudinal skin joints, frames and tear   MSD/MED
 straps.
Circumferential joints and stringers......  MSD/MED
Fuselage frames...........................  MED
Lap joints with milled, chem.-milled, or    MSD
 bonded radius.
Stringer-to-frame attachments.............  MED
Shear clip end fasteners on shear tied      MSD/MED
 fuselage.
Aft pressure dome outer ring and dome web   MSD/MED
 splices.
Skin splice at aft pressure bulkhead......  MSD
Abrupt changes in web or skin thickness     MSD/MED
 (pressurized or unpressurized structure).
Window surround structure.................  MSD/MED
Overwing fuselage attachments.............  MED
Latches and hinges of nonplug doors.......  MSD/MED
Skin at runout of large doubler (MSD),      MSD
 fuselage, wing, or empennage.
Rib to skin attachments...................  MSD/MED
Typical wing or empennage structure.......  MSD/MED
Wing and empennage chordwise splices......  MSD/MED
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B. History of WFD in Transport Category Airplanes

    In April 1988, an 18-foot section of the upper fuselage of an Aloha 
Airlines Boeing Model 737 airplane separated from the airplane en route 
from Hilo to Honolulu, Hawaii. The National Transportation Safety Board 
determined that, among other things, WFD was a contributing cause of 
this accident. Since then, WFD appears to have played a role in several 
safety incidents involving large transport airplanes, although there 
has not been a catastrophic accident directly attributable to WFD. In 
particular, the FAA has issued or is in the process of issuing 
Airworthiness Directives (ADs) addressing aft pressure bulkhead cracks, 
lap splice cracks, and frame cracks.

C. Industry Input/Aviation Rulemaking Advisory Committee

    The FAA has tasked the ARAC to address several issues related to 
widespread fatigue damage. In 2001, the ARAC recommended imposing a 
limit on the validity of maintenance programs, requiring an evaluation 
of repairs, alterations and modifications, and providing a means of 
extending the limit of validity of the maintenance program for large 
transport category airplanes. The ARAC also recommended that elements 
of the existing aging airplane program be included or referenced in the 
Airworthiness Limitations section (ALS) of the Instructions for 
Continued Airworthiness (ICA). In 2003, the ARAC recommended imposing a 
limit on the validity of maintenance programs for all

[[Page 19930]]

newly certificated transport category airplanes.
    The ARAC recognized that structural fatigue characteristics of 
airplanes are only understood up to a point in time consistent with the 
analyses performed and the amount of testing accomplished. The 
maintenance program inspections related to structural fatigue are based 
on the results of these analyses and tests. Therefore, these 
inspections may need to be supplemented by further inspections, 
modifications, or replacements, if operation beyond a certain point is 
planned. The ARAC recommended that there should be a ``limit of 
validity of the maintenance program'' to limit the operation of an 
airplane. Once an airplane reached this limit, the operator should no 
longer operate the airplane, unless the operator has incorporated an 
extended limit of validity and any necessary service information into 
its maintenance program.

D. Current Regulations and Programs Related to WFD

1. Existing Design Criteria
    In the design process, a type certificate applicant generally 
establishes an expected economic life for the airplane, known as a 
design service goal. Applicants traditionally defined the design 
service goal early in the development of a new airplane, based on 
economic analyses, past service experience with prior models, and in 
some cases fatigue testing. Design approval holders have also performed 
additional fatigue tests, teardown inspections, and analyses to support 
changing design service goals to extended service goals. The 
regulations required applicants and design approval holders only to 
show that individual fatigue cracks would not lead to catastrophic 
structural failure. Since 1978, 14 CFR 25.571 has required applicants 
for new type certificates for transport category airplanes to establish 
inspections to detect fatigue cracks before they can grow to the point 
of catastrophic failure (43 FR 46242, October 5, 1978). These 
inspections are documented in the ALS.
    In 1998, the FAA amended the aircraft certification requirements 
for transport category airplanes (63 FR 15707, March 31, 1998). As part 
of the certification process, section 25.571 now requires full-scale 
fatigue test evidence to demonstrate that WFD will not occur before an 
airplane reaches its design service goal. Only a few airplane models 
are subject to this new requirement, because the applications for most 
type certificates predate 1998. Even with the requirement to perform 
full-scale fatigue testing, there is no requirement to limit the 
operation of an airplane once it reaches the design service goal.
2. Instructions for Continued Airworthiness
    As part of the current certification process, TC holders and STC 
holders who applied for a certificate after January 28, 1981 are 
required by Sec.  21.50 to make available at least one set of complete 
ICA to the owner of the airplane. The ICA must include inspection and 
replacement instructions for airplane structure. Also, any person who 
makes a design change to airplane structure must provide the airplane 
owner with a complete set of the ICA for that change.
    In developing the ICA, the applicant is required to include certain 
information, such as a description of the airplane and its systems, 
servicing information, and maintenance instructions (Sec.  25.1529). 
The applicant must include the frequency and extent of the structural 
inspections necessary to provide for the continued airworthiness of the 
airplane as well as an FAA-approved ALS listing all mandatory 
inspections, inspection intervals, replacement times, and related 
procedures. The FAA requires operators to comply with each ALS 
established under Sec.  25.1529 for newly certified airplanes or with 
operation specifications approved under part 121 or 135. Operators may 
also incorporate tasks--from a Maintenance Review Board document that 
has been approved by the FAA \2\--into their maintenance program.
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    \2\ The FAA establishes a Maintenance Review Board comprised of 
subject matter experts who oversee development of a maintenance 
program for a specific airplane. In conjunction with the work of the 
review board, an industry steering committee comprised of 
representatives from the applicant, operators, and the FAA, analyzes 
maintenance requirements for that specific airplane. The review 
board and the steering committee then produce a Maintenance Review 
Board document that contains, among other task, inspections of the 
airplane structure. These inspections, in conjunction with any 
airworthiness limitation items established under Sec.  25.271, 
address accidental damage environmental damage, and fatigue damage.
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3. Airworthiness Directives
    The FAA currently issues ADs when we find that an unsafe condition 
exists in a product and the condition is likely to exist or develop in 
other products of the same type design. Because WFD could lead to a 
catastrophic failure due to reduction of the strength capability of the 
structure, we would issue an AD to address a finding of WFD in a 
particular product. An AD typically addresses an unsafe condition by 
requiring inspection, modification, or replacement of certain 
structure, or a combination of these approaches. ADs are reactive and 
address only known instances of WFD. Additionally, ADs are directed 
towards a specific group of airplanes. Hence, WFD may go undetected in 
other airplanes with similar structures.
4. Aging Aircraft Program
    In October 1991, Congress enacted the Aging Aircraft Safety Act of 
1991 (49 U.S.C. 44717) to address aging aircraft concerns. In response 
to the Act, the FAA published an interim final rule that amended 
Sec. Sec.  121.368, 121.370a, 129.16, and 129.33 of the air carrier 
operating rules (67 FR 72726, December 6, 2002). Sections 121.368 and 
129.33 require mandatory records reviews and airplane inspections after 
the airplane has been in service 14 years. In addition, Sec. Sec.  
121.370a and 129.16 require damage-tolerance-based inspections and 
procedures on airplanes operated under 14 CFR parts 121 and 129, 
respectively.
    In response to the Aloha Airlines accident, the FAA formed the 
Airworthiness Assurance Task Force to investigate and propose solutions 
to the problems evidenced as a result of the accident. The task force 
was comprised of operators, manufacturers, and regulatory authorities. 
The task force recommended establishment of an Aging Airplane Program. 
Under the Aging Airplane Program, the FAA has mandated the following 
four separate programs:
     Supplemental Structural Inspection Programs for certain 
large transport category airplanes;
     Corrosion Prevention and Control Programs for certain 
large transport category airplanes;
     Repair Assessment Program to ensure existing and future 
repairs to the fuselage pressure boundary are assessed for damage 
tolerance.
     Mandatory Modification Program, based on the premise that 
to ensure the structural integrity of older airplanes there should be 
less reliance on repetitive inspections. (The determination of whether 
a modification is required is based on meeting certain criteria.)
    These four programs or their equivalent make up the current 
structural maintenance program that operators incorporate into their 
maintenance or inspection programs to address aging structures. 
However, none of the programs address widespread fatigue damage.

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5. Advisory Circulars
    We have considered issuing Advisory Circulars (ACs) to give 
guidance on the changes needed to prevent WFD. Advisory Circulars, 
however, depend on voluntary compliance and are not enforceable. 
Therefore, use of ACs alone would ensure neither consistent results nor 
achievement of the WFD safety objectives for the current and future 
fleet.\3\
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    \3\ Voluntary safety assessments, such as those relating to the 
thrust reverser and cargo door reviews, have been difficult to 
complete in a timely manner because they lacked enforceability.
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E. Summary of the Proposal

    Long-term reliance on existing requirements, even those that 
incorporate the latest mandatory changes introduced to combat 
structural degradation due to WFD, creates a risk of structural failure 
and related accidents because the requirements are inadequate to 
preclude WFD.
    To address WFD, we need a proactive approach, i.e., address 
conditions affecting safe flight that we know can happen--before they 
happen. This approach would require persons to analyze the causes of 
WFD in relation to the entire airplane and to analyze repairs, 
alterations, and modifications installed on the airplane.
    Based on the ARAC recommendations \4\ and our own analysis, we have 
determined that operators, TC holders, and STC holders need to place 
more emphasis on WFD. This proposal is designed to heighten the 
awareness of the threat of WFD to airplanes and to change the current 
approach to maintaining and modifying them. Table 2 summarizes the 
proposed regulatory changes discussed today.
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    \4\ ``Structural Fatigue Evaluation for Aging Airplanes'' 
(October, 1993); recommendation to add an appendix to AC 91-56, 
``Supplemental Structural Inspection Program (SSIP) for Large 
Transport Category Airplanes''; ``Recommendations for Regulatory 
Action to Prevent Widespread Fatigue Damage in the Commercial 
Fleet'' Rev. A (June, 1999); ``General Structures Harmonization 
Working Group Report Damage Tolerance and Fatigue Evaluation of 
Structures FAR/JAR Sec.  25.571'' (October, 2003).

                         Table 2.--Summary of Proposed Regulatory Changes Addressing WFD
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                14 CFR                 Description of proposal         Applies to            Compliance date
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Sec.   25.571........................  Replace ``design         Future applicants for    Before approval of TC
                                        service goal'' with      new Type Certificates    by Aircraft
                                        ``initial operational    (TC).                    Certification Office
                                        limit.''                                          (ACO).
                                       Require an initial
                                        operational limit as
                                        part of the
                                        Airworthiness
                                        Limitation Section
                                        (ALS) of the
                                        Instructions for
                                        Continued
                                        Airworthiness (ICA).
Sec.   25.1807.......................  Require initial          TC holders.............  December 18, 2007.
                                        operational limits for  Supplemental TC (STC)    December 18, 2007.
                                        all transport category   holders*.               Later of December 18,
                                        airplanes with a        Applicants for pending    2007, or date of
                                        Maximum Take-off Gross   TCs and STCs.*.          certificate.
                                        Weight (MTGW) greater   Applicants for new       Later of December 18,
                                        75,000 lb.               STCs* and amended        2007, or date of
                                                                 TCs.*.                   certificate.
                                       Establish WFD            TC holders.............  December 18, 2009.
                                        guidelines for          Applicants for TCs.....  Later of December 18,
                                        assessing repairs,                                2009, or date of
                                        alterations, and                                  certificate.
                                        modifications.
Sec.   25.1809.......................  Require WFD assessment   STC holders (other than  December 18, 2010.
                                        of all existing,         those covered by Sec.   Later of December 18,
                                        pending, and future       25.1807).               2010, or date of
                                        structural design       Applicants for pending    certificate.
                                        changes in               and future STCs and
                                        relationship to          amended TCs.
                                        initial operational
                                        limits; require
                                        development of any
                                        maintenance actions to
                                        preclude WFD.
Sec.   25.1811.......................   Establish requirements  Any person.............  Before approval of
                                        for extending any                                 extension by ACO.
                                        operational limits.
Sec.   25.1813.......................  Establish requirements   Any person seeking       Before approval of
                                        for evaluating certain   approval for repairs,    repairs, alterations,
                                        repairs, alterations,    alterations, or          or modifications by
                                        and modifications        modifications.           ACO.
                                        proposed for
                                        installation on
                                        airplanes with an
                                        extended operational
                                        limit.
Appendix H to part 25................  Require initial          Applicants for future    Before approval of TC
                                        operational limits as    TCs.                     by ACO.
                                        part of the ALS of the
                                        ICA.
                                       Require guidelines for
                                        evaluating WFD effects
                                        of repairs,
                                        alterations, and
                                        modifications.
Sec.   121.1115 Sec.   129.115.......  Require operators to     U.S. certificate         June 18, 2008.
                                        incorporate              holders and foreign
                                        operational limits       persons operating U.S.-
                                        into their maintenance   registered transport
                                        programs.                category airplanes.
                                       Require operators to     .......................  Before operating under
                                        incorporate any WFD                               extended operational
                                        airworthiness                                     limit.
                                        limitations for
                                        airplanes with
                                        extended operational
                                        limits.

[[Page 19932]]

 
                                       Establish requirements   .......................  Within 90 days after
                                        for identification and                            return to service,
                                        evaluation of certain                             following repairs,
                                        repairs, alterations,                             alterations, or
                                        and modifications                                 modifications.
                                        installed on airplanes
                                        operating under an
                                        extended operational
                                        limit.
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* Where STC increases MTGW to greater than 75,000 lb.
Note. There are also requirements for current holders of design approvals and those with pending design
  approvals to develop compliance plans, detailing how they will achieve compliance with the applicable
  requirements. For future applicants, similar information would be contained in a certification plan. To
  simplify the table above, these administrative requirements were omitted.

III. Requirements for Design Approval Holders

A. Ongoing Responsibility of Type Certificate Holders for Continued 
Airworthiness

    Several recent safety regulations necessitated action by air 
carriers and other operators but did not require design approval 
holders to develop and provide the necessary data and documents to 
facilitate the operators' compliance. Operators are often dependent on 
action by a design approval holder before they can implement new safety 
rules. Ongoing difficulty reported by operators in attempting to meet 
these rules has convinced us that corresponding design approval holder 
(DAH) responsibilities may be warranted under certain circumstances to 
enable operators to meet regulatory deadlines. When DAHs fail to 
provide the required data in a timely manner, operators may be forced 
to incur the costs associated with obtaining the expertise to develop 
the data. Some examples of programs in which some DAHs did not develop 
and make available the necessary information in a timely manner 
include:
     Thrust reversers, where it took 10 years to develop some 
service information AD-related items;
     Class D to Class C Cargo Conversions, where one TC holder 
did not develop the necessary modifications in time to support operator 
compliance and where several operators were unable to obtain timely 
technical support and modification parts from STC holders;
     The Reinforced Flight Deck Door Program, where most 
operators had substantially less than the one-year compliance time 
originally anticipated because of delays in developing and certifying 
the new designs;
     Repair Assessment Rule, where some operators were required 
to develop their own data for FAA approval in order to meet the rule's 
compliance date; and
     Structural Repair Manuals, where operators are still 
awaiting DAH action to perform damage tolerance evaluations and 
establish inspections, even though the DAH committed to completing this 
activity by 1993.
    In addition, DAHs have committed in the past to providing data to 
the FAA to support the certification basis of an airplane. In some 
instances, the DAH has missed the due date given for this commitment by 
up to 13 years.
    We intend to require type-certificate holders, manufacturers and 
others to take actions necessary to support the continued airworthiness 
of and to improve the safety of transport category airplanes. Such 
actions include performing assessments, developing design changes, 
revising ICAs, and making available necessary documentation to affected 
persons. We believe this requirement is necessary to facilitate 
compliance by air carriers with operating rules that in effect demand 
the use of new safety features.
    To address this problem, we propose to amend subpart A of part 25 
to expand its coverage and to add a new subpart I to establish 
requirements for current holders. As discussed in our final rule, 
``Fuel Tank Safety Compliance Extension and Aging Airplane Program 
Update'' (69 FR 45936, July 30, 2004), this and related proposals would 
add provisions to a new subpart I requiring actions by design approval 
holders that will allow operators to comply with our rules.
    Part 25 currently sets airworthiness standards for the issuance of 
TCs and changes to those certificates for transport category airplanes. 
It does not list the specific responsibilities of manufacturers to 
ensure continued airworthiness of these airplanes once the certificate 
is issued. Therefore, we propose to revise Sec.  25.1 by adding 
paragraph (c) to make clear that part 25 creates such responsibilities 
for holders of existing type and supplemental type certificates for 
transport category airplanes and applicants for approval of design 
changes to those certificates. Paragraph (d) would be added to make 
part 25 applicable to persons seeking approval of repairs, alterations, 
or modifications of certain transport category airplanes. This latter 
category is included, because repairs, alterations, and modifications 
can affect the structural integrity of the airplane. These changes may 
have an adverse effect on the continued airworthiness of the airplane. 
Those seeking approval of these changes should be aware of these 
effects and address these issues if relevant.
    In order to ensure the effectiveness of this change, we would also 
amend Sec.  25.2(d) (``Special retroactive requirements'') so as to 
require adherence to a new Subpart I which may require design changes 
and other activities by manufacturers when needed. The amended 
paragraph would also apply to persons seeking approval of repairs, 
alterations or modifications of transport category airplanes. This 
latter category is included because repairs, alterations and 
modifications can affect the structural integrity of the airplane. If 
the repairs, modifications or alterations are performed incorrectly, 
they may have an adverse effect on the continued airworthiness of the 
airplane.
    This proposal would establish a new subpart I, Continued 
Airworthiness and Safety Improvements, where we would locate rules 
imposing ongoing responsibilities on design approval holders. On July 
12, 2005, we issued policy statement PS-ANM110-7-12-2005, ``Safety--A 
Shared Responsibility--New Direction for Addressing Airworthiness 
Issues for Transport Airplanes'' (70 FR 40166). The policy states, in 
part, ``Based on our evaluation of more effective regulatory approaches 
for certain types of safety initiatives and the comments received from 
the Aging Airplane Program Update (July 30, 2004), the FAA has 
concluded that we need to adopt a regulatory approach recognizing the 
shared responsibility between design approval holders (DAHs) and 
operators. When we decide that general

[[Page 19933]]

rulemaking is needed to address an airworthiness issue, and believe the 
safety objective can only be fully achieved if the DAHs provide 
operators with the necessary information in a timely manner, we will 
propose requirements for the affected DAHs to provide that information 
by a certain date.''
    We believe that the safety objectives contained in this proposal 
can only be reliably achieved and acceptable to the FAA if the DAHs 
provide the operators with the initial operational limits required by 
the proposed operational rules for parts 121 and 129. Our determination 
that DAH requirements are necessary to support the initiatives 
contained in this proposal is based on several factors:
     Developing initial operational limits is complex. Only the 
airplane manufacturer, or DAH, has access to all the necessary type 
design data needed for the timely and efficient development of the 
required initial operational limit.
     FAA-approved operational limits need to be available in a 
timely manner. Due to the complexity of these initial operational 
limits, we need to ensure that the DAHs submit them for approval on 
schedule. This will allow the FAA Oversight Office having approval 
authority to ensure that the initial operational limits are acceptable, 
are available on time, and can be readily implemented by the affected 
operators.
     The proposals in this NPRM affect a large number of 
different types of transport airplanes. Because the safety issues 
addressed by this proposal are common to many airplanes, we need to 
ensure that technical requirements are met consistently and the 
processes of compliance are consistent. This will ensure that the 
proposed safety enhancements are implemented in a standardized manner.
     The safety objectives of this proposal need to be 
maintained for the operational life of the airplane. We need to ensure 
that future design changes to the type design of the airplane do not 
degrade the safety enhancements achieved by the incorporation of 
initial operational limits. We need to be aware of future changes to 
the type designs to ensure that these changes do not invalidate initial 
operational limits developed under the requirements of this proposal.
    Based on the above reasons and the stated safety objectives of FAA 
policy PS-ANM110-7-12-2005, we are proposing to implement DAH 
requirements applicable to operational limits.
    In the past, this type of requirement took the form of a Special 
Federal Aviation Regulations (SFAR). These regulations are difficult to 
locate because they are scattered throughout Title 14. Placing all 
these types of requirements in a single subpart of part 25 which 
contains the airworthiness standards for transport category airplanes 
would provide ready access to critical rules.
    In preliminary discussions with foreign aviation authorities with 
whom we try to harmonize our safety rules, they have expressed concern 
about consolidating parallel requirements in their counterparts to part 
25. They have suggested that it may be more appropriate to place them 
in part 21 or elsewhere. Therefore, we specifically request comments 
from the public, including foreign authorities, on the appropriate 
place for these airworthiness requirements for type certificate 
holders.
    We reserve additional sections in this proposed subpart to include 
other future aging airplane rules, several of which are under 
development. Some of these proposals include similar language 
establishing the general airworthiness responsibilities of 
manufacturers and thus include some overlapping provisions. Once any 
proposal establishing these broad responsibilities becomes a final 
rule, we will delete the duplicative requirements from the other 
proposals and retain only that language pertinent to any specific new 
safety regulations (such as fuel-tank flammability reduction).
    However, the ongoing-airworthiness requirements in Subpart I would 
not by their terms reach applicants for TCs with respect to new 
projects for which application is made after the effective date of the 
proposed rule. This is unnecessary, because when we adopt a new 
requirement for TC holders, there will be a corresponding amendment to 
part 25 expressly making the new, or a similar safety standard a 
condition for receiving a TC in the future. For example, in this 
proposal, the new requirements of Sec.  25.571 regarding WFD will 
govern future applications.
    For safety reasons, however, we are requiring that any application 
for a type design change not degrade the level of safety already 
created by the TC holder's presumed compliance with the subpart I rule. 
Currently, when reviewing an application for such a change, we employ 
the governing standards stated in part 21, specifically Sec.  21.101. 
That section generally requires compliance with standards in effect on 
the date of application but contains exceptions that may allow 
applicants to show compliance with earlier standards. For example, if a 
change is not considered ``significant,'' the applicant may be allowed 
to show compliance by pointing to standards that applied to the 
original TC. (See AC 21.101-1, ``Establishing the Certification Basis 
of Changed Aeronautical Products,'' a copy of which can be downloaded 
from http://www.airweb.faa.gov/rgl).
    With the adoption of subpart I rules, we must ensure that safety 
improvements that result from TC holder compliance with these 
requirements are not undone by later modifications. Therefore, even 
when we determine under Sec.  21.101 that applicants need not comply 
with the latest airworthiness standards, they will be required to 
demonstrate that the change would not degrade the level of safety 
provided by the TC holder's compliance with the subpart I rule. In the 
context of this proposal, for example, this will mean that an applicant 
for approval of a design change would have to perform a WFD evaluation 
to determine if any maintenance actions are necessary to preclude WFD.

B. Applicability

1. Holders of Type Certificates and Supplemental Type Certificates
    This proposal, if adopted, would impose requirements on TC holders 
for all large transport category airplanes. Under Sec.  25.571, an 
applicant for a TC would have to establish an initial operational limit 
for the contemplated airplane design as part of its application. 
Likewise, existing TC holders would have to establish an initial 
operational limit for all large transport category airplanes under 
Sec.  25.1807 if the MTGW of the airplane exceeds 75,000 lb. Type 
certificate and STC holders would also have to establish an initial 
operational limit for all large transport category airplanes under 
Sec.  25.1807 if the MTGW of the airplane was 75,000 pounds or less, 
and later increased to greater than 75,000 pounds by an amended type 
certificate or supplemental type certificate.
    This proposal, if adopted, would apply not only to domestic TC and 
STC holders, but also to foreign TC and STC holders. This rule would be 
different from most type certification programs for new TCs, where 
foreign applicants typically work with their responsible certification 
authority and the FAA relies to some degree upon that authority's 
findings of compliance under bilateral airworthiness agreements. 
Presently no other certification authority has adopted requirements 
addressing WFD for existing TCs. Additionally, while some

[[Page 19934]]

authorities have indicated an interest in adopting some type of 
requirements for new airplane designs, they may not adopt requirements 
applicable to existing TCs.
    Accordingly, the FAA will retain the authority to make all the 
necessary compliance determinations and, where appropriate, may request 
certain compliance determinations by the appropriate foreign 
authorities using procedures developed under the bilateral agreements. 
The compliance planning provisions of this proposed rule are equally 
important for domestic and foreign TC and STC holders and applicants, 
and we will work with the foreign authorities to ensure that their TC 
and STC holders and applicants perform the planning necessary to comply 
with those requirements.
2. Airplanes
    If adopted, this rule would apply, with some exceptions discussed 
below, to large transport category airplane designs (MTGW greater than 
75,000 pounds) by virtue of either the original certification of the 
airplane or a later increase in its MTGW. All transport category 
airplanes certificated under a TC that was applied for after the 
effective date of the final rule would also be subject to the 
requirements proposed today. This combined approach would result in the 
coverage of airplanes where the safety benefits and the public interest 
are the greatest.
    The ARAC working group that developed this recommendation did not 
include design approval holders for airplanes of less than 75,000 
pounds MTGW, in part because they were not asked to do so. However, in 
addition to its WFD recommendations, this working group developed 
recommendations on other aging airplane issues, including the 
Supplemental Structural Inspection Program, the Corrosion Prevention 
and Control Program, the Repair Assessment Program, and the Mandatory 
Modification Program. Because of these efforts, design approval holders 
for large transport category airplanes have already developed the 
technology and the internal organizational capability to address WFD. 
Therefore, the 75,000 pound MTGW is a logical reference point for 
developing programs for addressing WFD.
    We considered applying this proposal to all existing part 25 
airplanes. However, we have determined that smaller regional jets do 
not currently present a risk of WFD sufficient to justify the cost 
associated with meeting this proposal.
    The 75,000-pound cutoff excludes about 1,600 regional jets that are 
operating under parts 121 and 129 today. Of those airplanes, there are 
approximately 430 regional jets that are at least eight years old. 
These airplanes have accumulated an average of 12,000 flight cycles. 
The regional jet with the greatest number of flight cycles is 11 years 
old and has accumulated about 26,000 flight cycles, well below the 
existing design service goal for this airplane of 60,000 flight cycles.
    The FAA recognizes that using a cutoff of 75,000 pounds does not 
align with the FAA's ``One Level of Safety'' initiative (that is, the 
same level for all airplanes used in air carrier service). However, we 
determined a cutoff of 75,000 pounds to be appropriate at this time for 
the following reasons:
     This is the same cutoff used for the four aging airplane 
programs mentioned above, and the affected type certificate holders are 
able to address these problems now.
     Some airplanes over 75,000 pounds are at a greater risk 
due to higher total cycles and age.
     Most air carrier airplanes are of this size, and many of 
them are near or over their design service goal.
     The regional jets not affected are relatively young and, 
therefore, at low risk relative to WFD.
     The high-cycle regional jet will be in service for an 
additional 14 years before reaching its design service goal.
    The FAA may determine that we need to expand the scope of this rule 
at a later time, based on evaluations of the potential for WFD in 
regional jets. All of these regional jets are manufactured in other 
countries, and any efforts to address WFD should be developed in 
coordination with those countries. Until that time, if WFD problems are 
identified in these airplanes, we will address them through 
airworthiness directives. No WFD problems have yet been identified for 
regional jets. The FAA requests comments on this aspect of the proposed 
rule.
    While the ARAC recommendations applied to all transport category 
airplanes over 75,000 pounds, the group of airplanes of most concern is 
that group operating under parts 121 and 129. Because carriers in 
scheduled operations fly airplanes operated under those parts, they are 
flown more often than other airplanes of comparable size and are 
accordingly more likely to develop WFD. Thus, this proposal would 
exclude airplanes over 75,000 pounds that are not operated under parts 
121 or 129. For this reason, we have tentatively decided that this 
proposal, if adopted, should exclude the Bombardier BD-700, the 
Gulfstream G-V, the Gulfstream G-VSP, and the British Aerospace, 
Aircraft Group and Societe Nationale Industrielle Aerospatiale Concorde 
Type 1.
    It is not clear at this time that the possible benefits of this 
rule for those airplanes would be proportionate to the cost involved. 
We request comments on the feasibility and benefits of including or 
excluding these airplanes. We also request 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 
parts 121 and 129.

C. Initial Operational Limit (Sec.  25.571, Sec.  25.1807)

    Under this proposal, design approval holders would be required to 
establish an initial operational limit \5\ for all transport airplanes 
if certificated under a new TC and for those transport airplanes over 
75,000 pounds if certificated under an existing TC. Demonstration that 
WFD will not occur prior to the initial operational limit typically 
would involve an evaluation of the airplane model using fatigue test 
evidence, analyses, and airplane service information. Initial 
operational limits may also include specified maintenance actions 
necessary to preclude WFD, which would be addressed through the 
airworthiness directive process.\6\
---------------------------------------------------------------------------

    \5\ The most direct method for limiting the operation of an 
airplane is to prohibit operation beyond a certain point. For the 
purpose of this rule, we are using the term ``operational limit of 
an airplane'' rather than ``limit of valdity of the maintenance 
program'' as recommended by ARAC.
    \6\ We intend to use the AD process, so that operators will have 
an opportunity to comment on the contemplated maintenance actions.
---------------------------------------------------------------------------

    Airplane owners or operators may need to take certain maintenance 
actions to support the operational limits. These actions may include 
additional inspections, structural modifications, or replacements. The 
inspections would include an inspection start point and repetitive 
inspection intervals, along with inspection methods. Because 
inspections may not be reliable in detecting MSD or MED, structural 
modification points, which may include modifications or replacements, 
may eventually be required. Means of compliance with the requirements 
for performing a WFD evaluation and establishing an inspection start 
point and structural modification points will be further described in a 
proposed AC.
    To establish an initial operational limit, the FAA recognizes that 
the structural configuration of the airplane

[[Page 19935]]

needs to be identified. Thus, Sec.  25.1807 would specify the airplane 
structural configurations that must be evaluated. As a minimum, the 
structural configuration would consist of all model variations and 
derivatives approved under the type certificate and all structural 
modifications and replacements mandated by ADs as of the effective date 
of the rule. These ADs would only be those issued against any 
configurations developed by TC holders. They would not be for any ADs 
issued against modifications defined by an STC installed on affected 
airplanes. The result would be an airplane structural configuration 
that is clearly understood by both industry and the FAA.
    The initial operational limit would be stated as a number of total 
accumulated flight cycles or flight hours. An initial operational limit 
based on flight hours may be required for structure, such as the wings, 
that typically accumulates fatigue damage due to the repeated flight 
loads that occur on an airplane over time. An initial operational limit 
based on flight cycles may be required for structure, such as the 
fuselage, that typically accumulates fatigue damage due to the 
pressurization and depressurization of an airplane. There is no way to 
correlate between the two limits without knowing the applicable design 
and operational variables, such as average flight length. Accordingly, 
design approval holders may need to establish both a flight hour limit 
and a flight cycle limit.
    The initial evaluation of the airplane structural configuration 
should identify a projected airplane usage beyond its design service 
goal (DSG). This projected airplane usage is also known as the 
``proposed extended service goal'' (ESG). Typically, an evaluation 
through at least an additional twenty-five percent of the DSG would 
provide a realistic ESG. The ESG would be based on an additional 
evaluation of the airplane structural configuration and depends on the 
following:
     The projected useful life of the airplane at the time of 
the initial evaluation;
     Current inspection techniques and procedures; and
     Airline advance planning requirements for introduction of 
new maintenance actions, to support the ESG.
    Design approval holders may select DSGs or ESGs as starting points 
for establishing initial operational limits. Service information may be 
available for design approval holders to make those initial operational 
limits higher. In fact, the FAA is aware that design approval holders 
may have service information, such as service bulletins or all operator 
letters that could have an impact on proposed initial operational 
limits, but have not been mandated by AD. We are also aware that these 
persons may be in the process of developing service information that 
could have an impact on proposed initial operational limits. They may 
choose to specify additional maintenance actions resulting from such 
service information that could result in higher initial operational 
limits.
    Accordingly, the proposed rule includes an option for design 
approval holders to use existing maintenance actions for which service 
information has not been mandated by AD. These maintenance actions 
would be in addition to the airplane structural configurations that 
design approval holders would evaluate under the proposed regulation. 
To use this option, the affected design approval holders would be 
required to submit a list identifying the existing maintenance actions 
to the FAA oversight office. The affected design approval holders would 
then establish initial operational limits based on WFD evaluations that 
take credit for existing maintenance actions.
    The proposed rule also includes an option for affected design 
approval holders to use maintenance actions for which service 
information has not been issued. Those maintenance actions would be in 
addition to the airplane structural configurations that must be 
evaluated. To use this option, the affected persons would be required 
to submit a list identifying each of those maintenance actions and a 
binding schedule for providing in a timely manner the necessary service 
information for those actions to the FAA oversight office. The binding 
schedule is necessary to ensure the applicable service information is 
provided to the FAA in sufficient time for the agency to issue ADs 
mandating these actions, and operators to comply with them before WFD 
occurs. The design approval holders would then establish initial 
operational limits based on WFD evaluations that take credit for 
maintenance actions for which service information has not been issued.
    The WFD evaluation would consist of identifying structure 
susceptible to multiple site damage or multiple element damage based on 
the configurations discussed above. Once the structure has been 
identified, affected design approval holders would determine when WFD 
is likely to occur. This WFD evaluation would be based on consideration 
of the following:
     Service history: reported findings of multiple site damage 
or multiple element damage.
     Test data: WFD information from past component or full-
scale test results. This could include information on susceptibility of 
structure to WFD, crack initiation life, crack growth life, and 
residual strength.
     Fatigue analyses: predictions of times when multiple site 
damage or multiple element damage cracking would occur.
     Damage tolerance analyses: predictions of multiple site 
damage or multiple element crack growth life and residual strength.
     Teardown inspections of high-usage airplanes.
    Certain design approval holders have revealed to the FAA their 
plans to establish initial operational limits that would be 130 to 150 
percent of the DSG or ESG for their airplanes. They have also started 
to identify the necessary maintenance actions, including the inspection 
and modification start points, to preclude WFD up to the established 
initial operational limits for these airplanes. Many inspection and 
modification start points would be approximately at the design service 
goal or, in some cases, at 125 percent of the design service goal. This 
would support an initial operational limit that could be substantially 
higher than the DSG or ESG for a particular airplane. Other design 
approval holders have indicated that the initial operational limits for 
their airplanes would be at DSG or ESG. This is because relatively few 
of their airplanes are in operation today or all of their airplanes are 
many years away from accumulating the number of flight cycles shown in 
Table 3.
    Table 3 provides estimates of DSGs and ESGs of various airplanes 
that would be affected by this proposal. These DSGs and ESGs are based 
on information provided by type certificate holders or on a 
conservative estimate by the FAA.

[[Page 19936]]



               Table 3.--Design and Extended Service Goals
------------------------------------------------------------------------
                                                           Service goals
         Airplane type              Type  certificate       (in flight
                                                              cycles)
------------------------------------------------------------------------
Airbus:
    A300 B2-1A, B2-1C and B2K-  A35EU...................          48,000
     3C.
    A300 B4-2C and B4-103.....  A35EU...................          40,000
    A300 Model B4-203.........  A35EU...................          34,000
    A300 B4-600 Series, B4-     A35EU...................          30,000
     600R Series and F4-600R
     Series.
    A310-200 Series...........  A35EU...................          40,000
    A310-300 Series...........  A35EU...................          35,000
    A319 (all models).........  A28NM...................          48,000
    A320 (all models).........  A28NM...................          48,000
    A321 (all models).........  A28NM...................          48,000
    A330 (all models).........  A46NM...................          40,000
    A340 (all models).........  A43NM...................          20,000
------------------------------------------------------------------------
Boeing:
    Boeing 707 (-100 series     4A21....................          20,000
     and -200 series).
    Boeing 707 (-300 series     4A26....................          20,000
     and -400 series).
    Boeing 717 (all models)...  A6WE....................          60,000
    Boeing 720................  4A28....................          30,000
    Boeing 727................  A3WE....................          60,000
    Boeing 737................  A16WE...................          75,000
    Boeing 747................  A20WE...................          20,000
    Boeing 757................  A2NM....................          50,000
    Boeing 767................  A1NM....................          50,000
    Boeing 777................  T00001SE................          44,000
------------------------------------------------------------------------
Bombardier Aerospace Model:
    CL-44D4 and CL-44J........  1A20....................          20,000
------------------------------------------------------------------------
British Aerospace Airbus,
 Ltd.:
    BAC 1-11 (all models).....  A5EU....................          85,000
British Aerospace (Commercial
 Aircraft) Ltd.:
    Armstrong Whitworth Argosy  7A9.....................          20,000
     A.W. 650 Series 101.
------------------------------------------------------------------------
BAE Systems (Operations) Ltd.:
    BAE 46 (all models) and     A49EU...................          50,000
     Avro 146.
    RJ70A, RJ85A and RJ100A
     (all models).
------------------------------------------------------------------------
Fokker:
    F28/F70/F100 (all models).  A20EU...................          90,000
------------------------------------------------------------------------
Lockheed:
    300-50A01 (USAF C 141A)...  A2SO....................          20,000
    L-1011 (all models).......  A23WE...................          36,000
    L188 (all models).........  A1SO....................          26,600
    382 (all models)..........  4A22....................          20,000
    1649A-98..................  4A17....................          20,000
    1049-54, 1049B-55, 1049C-   6A5.....................          20,000
     55, 1049D-55, 1049E-55,
     1049F-55, 1049G-82.
    49-46, 149-46, 649-79,      A-763...................          20,000
     649A-79, 749-79, 749A-79.
------------------------------------------------------------------------
McDonnell Douglas:
    DC-6......................  A-781...................          20,000
    DC-6A (all models)........  6A3.....................          20,000
    DC-6B (all models)........  6A4.....................          20,000
    DC-7 (all models).........  4A10....................          20,000
    DC-8 (all models).........  4A25....................          50,000
    DC-9 (all models).........  A6WE....................         100,000
    DC-10-10..................  A22WE...................          42,000
    DC-10-30, -40.............  A22WE...................          30,000
    MD-10-10F.................  A22WE...................          42,000
    MD-10-30F.................  A22WE...................          30,000
    MD-11 (all models)........  A22WE...................          20,000
    MD-80 (all models)........  A6WE....................          50,000
    MD-90-30..................  A6WE....................          60,000
------------------------------------------------------------------------


[[Page 19937]]

D. Instructions for Continued Airworthiness (Sec.  25.571, Sec.  
25.1807, Sec.  25.1811, Appendix H)

    We propose to require inclusion of the initial operational limit in 
the ALS of the ICA. This limit would be stated as a number of total 
accumulated flight cycles or flight hours. We will publish a notice in 
the Federal Register informing the public that the initial operational 
limits are available on an FAA website when this information is 
received from the design approval holders.
     For those persons that applied for a TC after the 
effective date of the rule, the ICA, which includes the ALS, would be 
provided with an airplane upon delivery. This ICA would also include 
guidelines to assist in addressing future repairs, alterations, and 
modifications so that they do not compromise this initial operational 
limit.
     For those TC holders that currently have an ALS, the ALS 
would be revised to include the initial operational limit. For those TC 
holders with airplanes that currently do not have an ALS, the ALS would 
be established to include the initial operational limit.
     For any person who applies for an extended operational 
limit, we propose to require inclusion of that limit in a supplement to 
the ALS. This extended operational limit may include service 
information documented as airworthiness limitation items that must be 
accomplished to support the extended operational limit.
    The ALS is required by current part 25 and includes those items 
that have mandatory inspection or replacement times related to 
structure. However, the current part 25 ALS and ICA requirements apply 
only to airplanes certified after amendment 25-54 became effective in 
1980. As a result, they are not applicable to many current airplanes.
    For those TC holders with airplanes that currently do not have an 
ALS, the ALS would address only initial operational limits. This 
proposal would not require that the ALS for these airplanes include the 
other requirements for an ALS established under amendment 25-54 to part 
25, or a later amendment.
    Assuming the final rule for this proposal is effective December 18, 
2006, this proposal would set a 12-month timeframe for development of 
the ALS, unless previously accomplished, to include initial operational 
limits. TC holders would be required to comply by December 18, 2007. 
Persons who have pending applications for TCs would be required to 
comply by December 18, 2007, or the date a certificate is issued, 
whichever occurs later. Holders or applicants for STCs, or amendments 
to TCs, that increase the maximum takeoff gross weight to greater than 
75,000 pounds would be required to comply by December 18, 2007, or, in 
the case of applicants, the date a certificate is issued, whichever 
occurs later.
    In determining the compliance schedules for the proposed 
requirements, we balanced the safety-related reasons for the rule 
against the need to give industry sufficient time to comply. Therefore, 
before setting the proposed compliance dates for analysis completion, 
we considered the following:
     Alignment with current or planned compliance dates of 
several aging-related rulemakings, such as the Aging Airplane Safety 
rule (FR cite), Fuel Tank System safety initiatives (69 FR 45936, 66 FR 
23086), and Enhanced Airworthiness Program for Airplane Systems/Fuel 
Tank Safety (69 FR 58508, October 6, 2005).
     Safety improvements that will result from compliance with 
this rule.
     Industry's current efforts to incorporate some of these 
safety initiatives.
    However, the rulemaking process took longer than originally 
anticipated. Consequently, given the specific compliance dates in the 
proposed rulemaking and the likelihood that finalization of the rules 
will be later than expected, there may not be as much time allowed for 
compliance as originally planned. We recognize that compliance 
intervals may need to be adjusted and will consider your comments on 
this condition.

E. Service Information and Guidelines for Repairs, Alterations and 
Modifications (Sec.  25.1807(g), Appendix H)

    The proposal would require affected persons to submit for FAA 
approval WFD service information and guidelines for addressing repairs, 
alterations, and modifications. Operators often use manufacturers' 
data, such as structural repair manuals and service bulletins, to 
repair or modify their airplanes. Such repairs or modifications could 
be made at any time during the service life of the airplane. This 
proposal would require TC holders to evaluate repairs and modifications 
identified in their structural repair manuals, service bulletins, and 
other service information and design approvals. The evaluation of these 
repairs and modifications is necessary to determine if and when WFD is 
likely to occur. If the evaluation concludes that WFD is likely to 
occur before the initial operational limit, then service information 
for maintenance actions must be developed and submitted to the FAA 
oversight office for approval. Once approved, we would issue ADs that 
would require operators to perform the maintenance actions.
    Because TC holders are the only persons with sufficient knowledge 
of the airplane to be able to develop the guidelines, they would also 
be required to develop and submit WFD guidelines for evaluating 
repairs, alterations, and modifications susceptible to WFD other than 
those for which they are responsible. The guidelines would use criteria 
similar to those used to evaluate the full airplane structural 
configurations discussed above and could include service history, 
fatigue analysis, test data, or damage tolerance analysis. The 
guidelines would provide a means to identify repairs, alterations, or 
modifications that may be susceptible to WFD. As discussed earlier, we 
have tasked ARAC to provide recommendations for methods to develop this 
type of guidance. We will provide guidance for development of these 
guidelines in a proposed AC.
    We anticipate the guidelines would have the necessary data to allow 
others to identify and perform an evaluation of repairs, alterations, 
and modifications. Also, these guidelines would support identification 
and evaluations of STCs and repairs, alterations, and modifications to 
those STCs. They could be used to develop extended operational limits 
and evaluate repairs, alterations, and modifications for those 
airplanes with extended operational limits. These guidelines would 
contain data for development of service information that would include 
possible maintenance actions that, as stated earlier, may include 
inspection start points, structural modification points, and inspection 
intervals and methods.
    We propose a compliance date of December 18, 2009, or the date the 
certificate is issued, whichever occurs later, for affected persons to 
submit service information and guidelines for approval by the FAA 
oversight office. We consider development of initial operational limits 
to be the most pressing concern. Accordingly, we would provide TC 
holders and applicants with additional time to address repairs, 
alterations, and modifications after the development of initial 
operational limits. This will enable TC holders and applicants to use 
the results of the ARAC tasking discussed earlier.

[[Page 19938]]

F. Changes to Type Certificates (STCs and Amended TCs) (Sec.  25.1809)

    STC holders, or applicants for design changes, would be required to 
perform a WFD evaluation to determine if the design change, or 
structure affected by the design change, requires maintenance actions 
prior to the initial operational limit.\7\ Affected structure can be 
new structure installed by a design change or existing structure 
modified by a design change. Structure may be affected if it is 
physically changed or there is a change or redistribution of internal 
loads. The following types of repairs, alterations or modifications are 
likely to have WFD implications:
---------------------------------------------------------------------------

    \7\ Those design changes that increase the maximum takeoff gross 
weight from 75,000 pounds or less, to greater than 75,000 pounds 
would be excluded, because they are covered in Sec.  25.1807.
---------------------------------------------------------------------------

     Passenger-to-freighter conversions (including addition of 
main deck cargo doors).
     Gross weight increases (increased operating weights, 
increased zero fuel weights, increased landing weights, and increased 
maximum takeoff weights).
     Installation of fuselage cutouts (passenger entry doors, 
emergency exit doors or crew escape hatches, fuselage access doors, and 
cabin window relocations).
     Complete re-engine or pylon modifications.
     Engine hush-kits and nacelle alterations.
     Wing modifications such as installing winglets or changes 
in flight control settings (flap droop), and alteration of wing 
trailing edge structure.
     Modified, repaired, or replaced skin splices.
     Any modification, repair, or alteration that affects 
several stringer or frame bays.
     A modification that covers structure requiring periodic 
inspection by the operator's maintenance program.
     A modification that results in operational mission change 
that significantly changes the manufacturer's load or stress spectrum, 
e.g., passenger-to-freighter conversion.
     A modification that changes areas of the fuselage that 
prevents external visual inspection, e.g., installation of a large 
external fuselage doubler that results in hiding details beneath it.
    This proposal would require evaluation of affected structure and 
any additional service information to determine if the structure is 
susceptible to multiple site damage or multiple element damage. This 
evaluation would be performed using manufacturers' guidelines or 
guidelines approved by the FAA oversight office. Affected persons would 
be required to use one of the approved procedures for screening design 
changes for standardization purposes. The proposed requirements would 
impose the same level of evaluation as proposed for TC holders in 
determining an initial operational limit.
    The guidelines would provide affected persons with a means to 
identify whether affected structure is susceptible to WFD. It would 
also provide a standardized WFD methodology for evaluating any design 
changes and determining their impact on surrounding structure. The 
guidelines would specify criteria to determine if additional 
maintenance actions are required. If an affected person determines that 
the design change does not cause a WFD concern, then no further action 
is required.
    For future design changes, the ALS developed with the ICA would 
include any associated service information that is necessary to enable 
the airplane to reach the initial operational limit. This service 
information would be documented as airworthiness limitation items 
(ALIs). Under Sec.  91.403(c), compliance with airworthiness 
limitations is mandatory, so the effect of documenting these actions as 
ALIs is that operators using the design change would be required to do 
them.
    The following compliance dates for evaluating design changes and 
developing service information for maintenance actions that must be 
performed to preclude WFD would need to be met:
     Holders of STCs: no later than December 18, 2010.
     Applicants for STCs and for amendments to STCs: no later 
than December 18, 2010, or the date the certificate is issued, 
whichever occurs later.

G. Extended Operational Limit (Sec.  25.1811, Sec.  25.1813)

    This proposal, if adopted, would permit operation of an airplane 
past its existing (initial or extended) operational limit if a person 
were able to demonstrate that WFD will not occur in the airplane up to 
the proposed extended operational limit. Any person wanting to operate 
beyond an existing operational limit would be required to perform an 
evaluation to that end as part of the amended TC (subpart D of part 21) 
or STC (subpart E of part 21) process. The extended operational limit 
may also include specified maintenance actions necessary to preclude 
WFD, which would be part of the extended operational limit approval. 
Extended operational limits would be established in an ALS using the 
requirements of Sec.  25.1529, along with corresponding ALIs. This 
proposed requirement does not specify a compliance plan since the 
normal process for obtaining approvals under the provisions of subparts 
D and E of part 21 already contemplates such a plan.
    To establish an extended operational limit, the structural 
configuration of each affected airplane needs to be identified as 
follows:
     All model variations and derivatives approved under the 
type certificate for which extension is sought.
     Any maintenance actions identified by the TC or STC holder 
as necessary to support the initial operational limit established under 
Sec.  25. 571 or Sec.  25.1807.
     All structural repairs, alterations, and modifications 
installed on each affected airplane, whether or not required by AD, up 
to the date of approval of the extended operational limit.
    Unlike the proposed requirements for initial operational limits, 
applicants might have to conduct separate evaluations on each affected 
airplane because of configuration differences rather than relying on a 
single evaluation for a group of airplanes. The configuration for any 
one airplane may consist of repairs, alterations, or modifications that 
are unique to that airplane. Applicants might also need to consider 
additional fatigue testing because the fatigue testing that supported 
the initial operational limit may not be sufficient to support the 
proposed extended operational limit. The service information for any 
necessary maintenance actions would be documented as an ALI.
    Extending the operational limit of an airplane raises implications 
for the validity of any subsequent repairs, alterations or 
modifications. Accordingly, any person seeking approval for 
installation of any repair, alteration, or modification would be 
required to perform an evaluation of that repaired, altered, or 
modified structure. Persons seeking approval of any repair, alteration, 
or modification would be required to use the guidelines specified in 
Sec.  25.1807, or other guidelines approved by the FAA oversight 
office. The guidelines would provide a standardized WFD methodology for 
evaluating any repair, alteration, or modification.
    The evaluation might conclude that a proposed repair, alteration, 
or modification is not susceptible to WFD or that WFD is not likely to 
occur before the subject airplane reaches the extended operational 
limit. As a result,

[[Page 19939]]

the person seeking approval would not be required to take any further 
actions for that proposed repair, alteration, or modification. 
Conversely, the evaluation might conclude that WFD is likely to occur 
before the affected airplane reaches the extended operational limit. 
Such an evaluation would require persons seeking approval to show that 
WFD is not likely to occur up to that limit either by modifying the 
proposed repair, alteration, or modification or by developing 
maintenance actions to be performed by the affected operator at 
identified times.

H. Compliance Plan (section 1807, section 1809)

    The FAA intends to establish the requirements for a compliance plan 
to ensure that affected persons and the FAA have a common understanding 
and agreement of what is necessary to achieve compliance with these 
sections. The plan will also ensure that the affected persons produce 
the ALS and service information and guidelines in a timely manner that 
are acceptable in content and format. Integral to the compliance plan 
will be the inclusion of procedures to allow the FAA to monitor 
progress toward compliance. These aspects of the plan will help ensure 
that the expected outcomes will be acceptable and on time for 
incorporation by the affected operators into their maintenance programs 
in accordance with the operational rules contained in this proposal.
    The affected design approval holders would be required to submit a 
compliance plan that addresses the following:
     The proposed schedule for meeting the compliance dates, 
including all major milestones.
     A proposed means of compliance with the initial 
operational limit requirement.
     Any planned deviations from guidance provided in FAA 
advisory material.
     A draft of all required compliance items not less than 60 
days before the stated compliance dates.
     Repairs, alterations, and modifications.
     Continuous assessment of the affected large transport 
category airplane fleet relative to the potential for WFD prior to the 
initial operational limit.
     Distribution of approved initial operational limits.
    The compliance plan is based substantially on ``The FAA and 
Industry Guide to Product Certification,'' which describes a process 
for developing project-specific certification plans for type 
certification programs, which is available at http://www.faa.gov/certification/aircraft.
    This guide recognizes the importance of ongoing communication and 
cooperation between applicants and the FAA. This proposal, while 
regulatory in nature, is intended to encourage the establishment of the 
same type of relationship in the process of complying with this 
section.
    One of the items required in the plan is, ``If the proposed means 
of compliance differs from that described in FAA advisory material, a 
detailed explanation of how the proposed means will comply with this 
section.'' We will issue an AC to include guidance on the aspects of a 
compliance plan. FAA advisory material is never mandatory because it 
describes one means, but not the only means of compliance. In the area 
of type certification, applicants frequently propose acceptable 
alternatives to the means described in advisory circulars. When an 
applicant chooses to comply by an alternative means, it is important to 
identify this as early as possible in the certification process to 
provide an opportunity to resolve any issues that may arise that could 
lead to delays in the certification schedule.
    The same is true of the requirement for design approval holders. As 
discussed earlier, compliance with this section on time by design 
approval holders is necessary to enable operators to comply with the 
operational requirements of this NPRM. Therefore, this item in the plan 
would enable the FAA oversight office to identify and resolve any 
issues that may arise with the proposal of the design approval holder 
without jeopardizing the ability of the design approval holder to 
comply by the compliance time.
    This proposal, if adopted, would require TC holders and applicants 
to correct a deficient plan, or deficiencies in implementing the plan, 
in a manner identified by the FAA oversight office. Before the FAA 
formally notifies a TC holder or applicant of deficiencies, we will 
communicate with them to try to achieve a complete mutual understanding 
of the deficiencies and means of correcting them. Therefore, the 
notification referred to in this paragraph should document the agreed 
corrections.
    The ability of an operator to comply with the proposed operating 
rules will be dependent on TC holders, certain STC holders, and 
applicants complying with Sec.  25.1807. The FAA will carefully monitor 
compliance and take appropriate action if necessary. Failure to comply 
by the specified dates would constitute a violation of the requirements 
and may subject the violator to certificate action to amend, suspend, 
or revoke the affected certificate (49 U.S.C. 44709). It may also 
subject the violator to a civil penalty of not more than $25,000 per 
day per certificate until the violator complies with Sec.  25.1807 (49 
U.S.C. 46301).
    This proposal, if adopted, would require a compliance date of March 
18, 2007, for affected persons to submit a compliance plan to the FAA 
oversight office for approval. For those persons applying after the 
effective date of the rule for STCs or amendments to TCs that increase 
maximum takeoff gross weights from 75,000 pounds or less, to greater 
than 75,000 pounds, a plan for WFD compliance would be part of the 
overall compliance plan for those STCs or amendments to TCs. The 
affected persons would not have to address WFD until a compliance plan 
defining the certification basis for the overall STC or amended TC is 
needed. Those persons would have to comply by March 18, 2007, or within 
90 days after the date of application, whichever occurs later.
    The proposal also specifies compliance dates for submitting 
compliance plans for evaluating design changes and developing service 
information for maintenance actions that must be performed to preclude 
WFD. The compliance dates for the affected persons are as follows:
     Holders of STCs: no later than March 18, 2008.
     Applicants for STCs and amendments to TCs, if the 
certificate was not issued before the effective date of the final rule: 
no later than March 18, 2008, or within 90 days after the date of 
application, whichever occurs later.

IV. Proposed Operational Rules

    In recent years, the FAA has identified a number of fleet-wide 
continued airworthiness issues that are not limited to particular type 
designs. Historically, we have issued ADs to require airplane operators 
to take corrective action to address these airworthiness issues. ADs 
are described in part 39. They address unsafe conditions that we 
determine are likely to exist or develop on other products of the same 
type design. Although ADs may be used to address fleet-wide issues, 
they are often more effective in addressing individual airplane issues. 
Accordingly, we believe that general rulemaking may be a more efficient 
and appropriate way to address fleet-wide safety problems. These new 
subparts provide locations for these types of requirements.

[[Page 19940]]

    Earlier in this document, we described the proposed creation of a 
new subpart I in part 25. That subpart would provide a common location 
for similar regulatory requirements. We are also proposing new subparts 
in parts 121 and 129. These new subparts would contain rules from this 
proposal and other existing and future rules that pertain to continued 
airworthiness, in particular rules that address aging airplane issues. 
The FAA believes that the new subparts will enhance the reader's 
ability to readily identify rules pertinent to continued airworthiness. 
Unless we say otherwise, our purpose in moving requirements to the new 
subparts is to ensure easy visibility of those requirements applicable 
to the continued airworthiness of the airplane. We do not intend to 
change their legal effect in any other way.
    A new subpart AA would be added to part 121 dealing with domestic 
air carriers and a new subpart B would be added to part 129 foreign air 
carriers and foreign persons operating U.S.-registered airplanes. This 
proposal, if adopted, would require persons holding an air carrier or 
operating certificate under part 119 to support the continued 
airworthiness of their airplanes. While most of the requirements of 
these subparts would address the need for improved maintenance, these 
subparts may also include requirements to modify airplanes or take 
other actions that we consider necessary for continued airworthiness.
    After June 18, 2008, an affected operator could not operate an 
airplane unless the operator has incorporated an ALS approved under 
appendix H to part 25 or Sec.  25.1807 into its maintenance program. 
This ALS would contain the operational limit stated as a number of 
total accumulated flight cycles or flight hours approved under Sec.  
25.571 or Sec.  25.1807. Furthermore, the ALS must be clearly 
distinguishable within the certificate holder's maintenance program. 
This means the ALS must be designated as a stand-alone portion of the 
program.
    Under both current and proposed Sec.  25.571, the FAA may issue a 
type certificate for an airplane model prior to completion of full-
scale fatigue testing. Under this proposal, the type certificate holder 
would establish the initial operational limit upon completion of this 
testing. As under current Sec.  25.571, the FAA intends for operators 
to be able to operate these airplanes while the design approval holder 
is performing the fatigue testing. Therefore, this proposal would not 
change the current provisions of Sec.  25.571 that, if a type 
certificate is issued prior to completion of full-scale fatigue 
testing, the ALS must include a number equal to \1/2\ 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 the number stated in the ALS until the fatigue 
testing is completed and the initial operational limit is established.
    Further operation would be prohibited unless an extended 
operational limit is incorporated into the operator's maintenance 
program, as discussed below.
    To use an extended operational limit, the proposal would require 
operators to revise their maintenance programs to do the following:
     Incorporate the ALS containing the extended operational 
limit and any WFD ALI approved under Sec.  25.1811.
     Incorporate the applicable guidelines for identifying and 
evaluating repairs, alterations, and modifications, that have been 
developed under Sec.  25.1807, or other guidelines approved by the FAA 
oversight office.
     Make the extended operational limit, WFD ALIs, and 
applicable guidelines clearly distinguishable.
    The extended operational limit might also have WFD ALIs because the 
evaluation performed under Sec.  25.1811 concluded that WFD may occur 
on certain structure before the extended operational limit is reached. 
These WFD ALIs may include inspection start points, structural 
modification points, and inspection intervals and methods. WFD ALIs may 
take the form of inspections, modifications, or replacements of WFD-
susceptible structure. The WFD ALI maintenance actions would be 
performed on airplane structure, including structure that has been 
repaired, altered or modified to support the extended operational 
limit. Any future proposed revisions to any of these ALIs would need to 
be submitted to the FAA oversight office through the Principal 
Maintenance Inspector (PMI) for approval.
    The applicable incorporated guidelines would provide a means for 
operators to identify and evaluate repairs, alterations, and 
modifications susceptible to WFD that have been installed on transport 
category airplanes operating under an extended operational limit. The 
only repairs, alterations or modifications needing a WFD evaluation 
would be those identified in the applicable guidelines and would not 
include TC holder's repairs identified according to Sec.  
25.1807(g)(1).
    The fatigue life on those repairs would generally be greater than 
the period of time the airplane has to go from its initial operational 
limit to its extended operational limit. For example, if a repair that 
has been identified in the TC holders structural repair manual has been 
evaluated to support an initial operational limit stated as 60,000 
flight cycles, then that repair would generally be valid up to 60,000 
flight cycles. If that repair is installed after an airplane is 
approved for an extended operational limit, the repair would generally 
be valid up to 60,000 flight cycles after installation. If we assume an 
extended operational limit of 75,000 total accumulated flight cycles 
for this example, and the airplane had 61,000 total accumulated flight 
cycles, the subject repair would generally be valid for the 14,000 
flight cycles remaining under the extended operational limit.
    The applicable guidelines would also provide a methodology for 
developing service information to support the extended operational 
limit. This service information would consist of maintenance actions 
that may include inspection, modification, or replacement of the 
repair, alteration, or modification. Operators would be required to 
perform a WFD evaluation of these repairs, alterations, or 
modifications using the applicable guidelines. If the evaluation 
concludes that WFD is likely to occur before the extended operational 
limit, the operator would need to develop any necessary maintenance 
actions according to Sec.  25.1813.
    The evaluation and proposed maintenance action would be submitted 
to the FAA oversight office through the operator's PMI for approval. 
This submittal process keeps PMIs informed and gives them the 
opportunity to provide comments on the repair, alteration, or 
modification to the operator and FAA oversight office.
    Operators would be required to evaluate any repair, alteration, or 
modification installed on the airplane after approval of an extended 
operational limit. The operator would use the guidelines developed 
according to the proposed Sec.  25.1807 and incorporated under the 
proposed operating rule. Operators would be required to complete the 
evaluation and identify any necessary additional maintenance actions, 
if applicable, within 90 days after returning an airplane to service. 
The operator would have 90 days after approval by the FAA oversight 
office to revise its maintenance program to incorporate any approved 
ALIs. This time period allows

[[Page 19941]]

for completion of the WFD evaluation and incorporation of any necessary 
maintenance actions into an operator's maintenance program. The 
airplane should not be at risk of structural failure due to WFD within 
the prescribed time period because WFD is a long-term fatigue problem.
    As with other maintenance actions, before returning an airplane to 
service, operators would be required under existing regulations to 
ensure that the repair, alteration, or modification meets immediate and 
short-term strength requirements, such as the ultimate static strength 
requirements specified in part 25. There may be other actions and 
approvals associated with returning the affected airplane to service. 
Those actions and approvals would still apply as before.
    Required maintenance program revisions would need to be submitted 
to the operator's PMI for review and approval. We are in the process of 
developing guidance for PMIs to ensure that their reviews are 
consistent and focused on the key implementation issues.

V. Additional Provisions

A. Relationship of This Proposal to Aging Airplane Regulatory 
Initiatives

    As part of our broader review of several important initiatives 
comprising the Aging Airplane Program, we have revised certain 
compliance dates in existing rules and pending proposals so that 
operators can make required modifications during scheduled maintenance. 
Changing compliance dates affects our ability to expedite some aspects 
of this program but reduces the costs of the rules and proposals in 
place to deal with aging airplanes. Notice of these changes and a 
description of our Aging Airplane Program review appeared in the 
Federal Register on July 30, 2004 (69 FR 45936). In addition to this 
Widespread Fatigue Damage proposal, the actions affected by these 
revisions include:
     Fuel Tank Flammability Reduction (proposal),
     Aging Airplane Safety (interim final rule), and
     Enhanced Airworthiness Program for Airplane Systems/Fuel 
Tank Safety (proposal).

B. FAA Advisory Material

    To help those persons affected by this proposed rule better 
understand what is necessary to show compliance with these proposed 
requirements, we are developing guidance material to supplement the 
proposed rule. We are revising AC 25.571-1C and proposing a new AC to 
include guidelines for the development of operational limits; service 
information for maintenance actions; and service information and 
guidelines for identifying and evaluating repairs, alterations, and 
modifications.
    We incorporated, in part, the ARAC recommendation to revise AC 
25.571-1C by including a definition for an initial operational limit; 
guidance for incorporation of the initial operational limit into the 
Airworthiness Limitations section; and guidance for providing evidence 
for demonstrating through full-scale fatigue testing that WFD will not 
occur before the initial operational limit.
    We also incorporated, in part, the ARAC recommendations to revise 
AC 91-56, ``Continuing Structural Integrity Program for Large Transport 
Category Airplanes.'' AC 91-56A, which was issued on April 29, 1998, 
added Appendix 2, ``Guidelines for the Development of a Program to 
Predict and Eliminate Widespread Fatigue Damage.''
    We are developing a new AC based, in part, on the ARAC 
recommendation to provide guidance for type certificate holders and 
others to perform WFD evaluations. The proposed AC includes:
     Guidelines for conducting a structural WFD evaluation.
     Illustrations of the structure susceptible to MSD and MED. 
These illustrations are by no means exhaustive and are included to 
stimulate the review of all possible affected structure.
     Guidance on developing a WFD prediction and verification 
technique.
     Evaluation of maintenance actions.
     Details of the documentation required by the FAA.
     Examples of structural repairs, alterations, and 
modifications.
    This AC would also provide guidance for operators of affected 
airplanes on how to incorporate an FAA-approved ALS with an initial 
operational limit into their FAA-approved maintenance program; 
incorporate an extended operational limit and any applicable ALI to 
preclude WFD; and incorporate any new ALI developed as a result of 
evaluations to address repairs, alterations, and modifications 
installed after incorporation of an extended operational limit.
    We invite public comments on the proposed ACs by separate notice, 
which will be published in the Federal Register.

C. FAA Oversight Office

    We are also requiring affected persons to submit various compliance 
materials related to WFD to the FAA Oversight Office, defined in 
proposed Sec.  25.1801(b). The FAA Oversight Office is the aircraft 
certification office or office within the Transport Airplane 
Directorate having oversight responsibility for the relevant TC or STC, 
as delegated by the Administrator. In other contexts, we have described 
the FAA office performing these functions as the ``cognizant FAA 
office.''
    Table 4 lists the FAA offices that currently oversee issuance of 
TCs and amended TCs for manufacturers of transport category airplanes.

          Table 4.--FAA Offices That Oversee Type Certificates
------------------------------------------------------------------------
          Airplane  manufacturer                FAA oversight office
------------------------------------------------------------------------
Aerospatiale..............................  Transport Airplane
                                             Directorate, International
                                             Branch, ANM-116.
Airbus....................................  Transport Airplane
                                             Directorate, International
                                             Branch, ANM-116.
BAE.......................................  Transport Airplane
                                             Directorate, International
                                             Branch, ANM-116.
Boeing....................................  Seattle Aircraft
                                             Certification Office.
Bombardier................................  New York Aircraft
                                             Certification Office.
deHaviland................................  New York Aircraft
                                             Certification Office.
Embraer...................................  Transport Airplane
                                             Directorate, International
                                             Branch, ANM-116.
Fokker....................................  Transport Airplane
                                             Directorate, International
                                             Branch, ANM-116.
Gulfstream................................  Atlanta Aircraft
                                             Certification Office.
Lockheed..................................  Atlanta Aircraft
                                             Certification Office.
McDonnell-Douglas.........................  Los Angeles Aircraft
                                             Certification Office.
------------------------------------------------------------------------

D. Need for Training

    The FAA recognizes that implementation of the proposed rule will be 
more complex than any other aging airplane program. We consider it 
essential that affected persons receive training to carry out the 
required actions. These persons include FAA PIs, Aviation Safety 
Inspectors, and ACO engineers, designees, operators, and maintenance 
personnel. We are developing training material based, in part, on the 
ARAC recommendations incorporated into this proposal and other 
considerations.
    This training would include, but is not limited to public meetings, 
FAA-only seminars, formal FAA and industry training sessions, and 
industry workshops to enhance communication among industry, operators, 
and the

[[Page 19942]]

FAA. The FAA requests comments on this aspect of the proposed rule.

VI. Rulemaking Notices and Analyses

Authority for This Rulemaking

    The FAA's authority to issue rules regarding 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.

Paperwork Reduction Act

    This proposal contains the following new information collection 
requirements. As required by the Paperwork Reduction Act of 1995 (44 
U.S.C. 3507(d)), the Department of Transportation has sent the 
information requirements associated with this proposal to the Office of 
Management and Budget for its review.
    Title: Widespread Fatigue Damage.
    Summary: This proposal consists of regulatory changes pertaining to 
widespread fatigue damage in transport category airplanes. Some of 
these changes would require new information collection. The proposed 
new information requirements and the persons who would be required to 
provide that information are described below.
    (1) Proposed subpart I would require that existing design approval 
holders establish initial operational limits for transport category 
airplanes. Those persons would also be required to revise the 
Airworthiness Limitation section of the Instructions for Continued 
Airworthiness (ICA) to include an initial operational limit. This 
requirement would be necessary to ensure that the affected airplanes 
are evaluated for WFD and that an initial operational limit is 
established beyond which an airplane cannot be operated. By 
establishing this limit it would be assured that WFD, which would 
adversely affect safety, would be precluded in the airplane.
    (2) Proposed subpart I would also require that design approval 
holders submit to the FAA a plan detailing how they intend to comply 
with the new requirements. The FAA would use this information to assist 
the design approval holder in complying with the new requirements. The 
compliance plan would be necessary to ensure that the design approval 
holders fully understand the requirements, correct any deficiencies in 
planning in a timely manner, and are able to provide the information 
needed by the operators for timely compliance with the rule.
    (3) TC holders would be required to develop guidelines for 
addressing repairs, alterations, and modifications susceptible to MSD 
or MED. These guidelines would be used to identify and evaluate 
repairs, alterations, and modifications that may be installed on an 
affected airplane. This requirement is needed because TC holders have 
the data necessary to inform others of areas of the airplane that may 
be susceptible to WFD when repaired, altered, or modified.
    (4) TC and STC holders would be required to develop service 
information to address repairs and modifications that would be 
susceptible to WFD before the airplane reaches the initial operational 
limit. Because this susceptibility is an unsafe condition, this service 
information would be mandated by airworthiness directive (AD) to 
support a proposed initial operational limit.
    (5) Anyone operating an airplane under parts 121 and 129 would be 
required to revise their maintenance program to incorporate an ALS that 
includes an initial operational limit. Operators would be prohibited 
from operating an airplane past the initial operational limit.
    (6) As an option, any person may apply for an extended operational 
limit for affected airplanes. This option would have requirements 
similar to those imposed on TC holders for establishing an initial 
operational limit. In addition, repairs, alterations, or modifications 
installed on an airplane with an extended operational limit would 
require identification and evaluation under Sec.  25.1807(g). There may 
be service information developed that would support the extended limit 
and would be documented as airworthiness limitation items (ALIs). To 
operate beyond the initial operational limit, an operator would have to 
incorporate the extended limit and any WFD ALI into its maintenance 
program.
    Use of: This proposal would support the information needs of the 
FAA in approving design approval holder and operator compliance with 
the proposed rule.
    Average Annual Burden Estimate: The burden would consist of the 
work necessary to:
     Develop the revision to the existing ICA information
     Develop the compliance plan
     Incorporate the new information into the existing 
maintenance program
    This proposed rulemaking would result in an annual recordkeeping 
and reporting burden as follows:

------------------------------------------------------------------------
                                                           Present value
  Documents required to show compliance   Average annual    discounted
         with the proposed rule                hours       cost ($2,000)
------------------------------------------------------------------------
FAA-approved revised or new ALS.........             132           8,606
FAA-approved WFD compliance plan........             436          16,759
FAA-approved guidelines for repairs,                 894          63,542
 alterations, and modifications.........
FAA-approved service information for                 276          16,288
 repairs and modifications relative to
 initial operational limit..............
FAA-approved maintenance program                      29           4,340
 revision for operators.................
FAA-approved program for extended                    132           8,606
 operational limit (if applicable)......
                                         -------------------------------
    Total...............................           1,899        $118,141
------------------------------------------------------------------------


[[Page 19943]]

    The FAA computed the annual recordkeeping (total hours) burden by 
analyzing the necessary paperwork requirements needed to satisfy each 
process of the proposed rulemaking. The average cost per hour varies 
due to the number of affected airplanes in each group, the amount of 
engineering time required to develop programs, and the amount of time 
required for each inspection.
    The agency is seeking comments to--
     Evaluate whether the proposed information requirement is 
necessary for the proper performance of the roles of the agency, 
including whether the information will have practical utility;
     Evaluate the accuracy of the agency's estimate of the 
burden;
     Improve the quality, utility, and clarity of the 
information to be collected; and
     Minimize the burden of the collection of information on 
those who are to respond using appropriate automated, electronic, 
mechanical, or other technological collection techniques or other forms 
of information technology.
    Individuals and organizations may submit comments to the FAA on the 
information collection requirement by July 17, 2006. You should send 
your comments to the address listed in the ADDRESSES section of this 
document.
    Under the Paperwork Reduction Act of 1995, (5 CFR 
1320.8(b)(2)(vi)), an agency may not conduct or sponsor, and a person 
is not required to respond to, a collection of information unless it 
displays a currently valid OMB control number. The OMB control number 
for this information collection will be published in the Federal 
Register, after the Office of Management and Budget approves it.

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 
determined there are no ICAO Standards and Recommended Practices that 
correspond to these proposed regulations.

VII. Regulatory Evaluation, Regulatory Flexibility Determination, 
International Trade Impact Assessment, and Unfunded Mandates Assessment

    This portion of the preamble summarizes the FAA's analysis of the 
economic impacts of this NPRM. It also includes summaries of the 
initial regulatory flexibility determination. We suggest readers 
seeking greater detail read the full regulatory evaluation, a copy of 
which we have 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, the FAA has determined this proposed 
rule: (1) Has benefits that justify its costs, is a ``significant 
regulatory action'' as defined in section 3(f) of Executive Order 
12866, and is ``significant'' as defined in DOT's Regulatory Policies 
and Procedures; (2) will have a significant economic impact on a 
substantial number of small entities; (3) will not reduce barriers to 
international trade; and does 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 proposed rule is based, in part, on recommendations from the 
Aviation Rulemaking Advisory Committee (ARAC). Early in 2001, the FAA 
performed an extensive cost-benefit analysis of the ARAC proposal based 
on the data then available. Since then the proposed rule has been 
modified and more recent data has become available. The FAA updated the 
2001 analysis to reflect changes in the proposed rule relative to the 
ARAC proposal. The FAA believes the analysis, as updated, properly 
reflects the cost and benefit determination. The FAA will further 
update the analysis, incorporating the latest data and information 
obtained from the NPRM, for the final rule. The costs of this proposal 
are the costs of the development of Widespread Fatigue Damage (WFD) 
programs by the airplane manufacturers and the incorporation of the WFD 
programs into the maintenance procedures of the airplane operators plus 
the inspection and structural modifications that may be required of the 
airplane operators. It is estimated that the total 20-year present 
value cost of this proposal is about $360 million. The benefits of this 
proposal consist of accident prevention and the prevention of 
unscheduled maintenance/downtime of fleets of aircraft. The present 
value benefits of this proposal, over 20 years, are estimated to be 
about $809 million.

Who Is Potentially Affected by This Rulemaking?

     Manufacturers of large transport category part 25 
airplanes (airplanes with a maximum gross takeoff weight greater than 
75,000 pounds).
     Applicants for type certificates or supplemental type 
certificates after the effective date of the rule for all transport 
category part 25 airplanes.
     Supplemental type certificate holders and applicants for 
amended part 25 type certificates.
     U.S. certificate holders and foreign air carriers and 
foreign persons operating U.S.-registered large transport category part 
25 airplanes under 14 CFR parts 121 or 129.

Our Cost Assumptions and Sources of Information

     Discount rate--7%
     Period of analysis--20 years, 2001 through 2020
     Value of fatality averted--$3.0 million (Source: U.S. 
Department of Transportation, Treatment of Value of Life and Injuries 
in Preparing Economic Evaluations, January 19, 2002)
     Aircraft Values = Aviation Specialists Group (ASG)
     Aircraft Operational Data = Aircraft Analytical System 
(ACAS) Database
     Aircraft Accident Data = NTSB Database
     Aircraft Forecasts = Boeing
     Unit Cost of WFD Inspections = Airworthiness Assurance 
Working Group (AAWG)
    In the design and certification process of an airplane, a type 
certificate applicant generally establishes an expected economic life 
for the airplane, known as a design service goal (DSG). For certain 
airplanes, design approval holders have performed additional fatigue 
tests, teardown inspections, and analyses to support changing DSG to 
extended service goals (ESG).

[[Page 19944]]

    For purposes of the cost/benefit analysis in this evaluation, we 
used the existing service goal for an airplane (whether the service 
goal is a (DSG or ESG) as an analytical starting point for the initial 
operational limits (IOLs). The existing service goals are listed in 
Table 3. We have assumed that additional costs of compliance will be 
incurred at 100% and potentially again at 125% of this service goal. We 
note that Boeing plans to establish IOLs that would be 130 to 150 
percent of the DSG or ESG for their airplanes. Since this action would 
support an IOL that could be substantially higher than the estimates 
used for a particular airplane, the costs of inspection and 
modification could exceed our estimates, while the costs of early 
retirement of useful airplanes could be less. Manufacturers of aircraft 
no longer in production, and with only a few airplanes in operation, 
are likely not to extend the current service goal.
    The FAA seeks comments on these assumptions, and future plans to 
extend DSG or ESG and the establishment of initial operational limits.

Alternatives We Considered

    The FAA considered five alternatives to the proposed rule. These 
were:
    1. Exclude small entities.
    2. Extend the compliance deadline for small entities.
    3. Establish lesser technical requirements for small entities.
    4. Expand the requirements to cover more airplanes.
    5. Retire airplanes at the manufacturer's design or extended 
service goal.
    The FAA concluded that Alternative 1, the option to exclude 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.
    The FAA also considered options that would lengthen the compliance 
period for small operators (Alternative 2). The FAA believes time 
extensions only provide modest cost savings and leave the system safety 
at risk.
    The FAA considered establishing lesser technical requirements for 
small entities (Alternative 3). 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.
    The FAA considered requiring all operators of existing transport 
category airplanes to comply with the proposed rule (Alternative 4). 
Over the past several years, TC holders have been addressing issues 
with aging airplane programs for airplanes with maximum takeoff gross 
weights greater than 75,000 pounds. Because of this, the FAA decided to 
restrict compliance to operators of those airplanes.
    The FAA considered mandating the retirement of airplanes at an 
initial operating limit equivalent to the manufacturer's current 
service goal (DSG or ESG). This alternative would not allow a DAH to 
establish a higher initial operation limit based on identifying 
additional maintenance actions (inspections, modifications, or 
replacements) that would preclude WFD up to this higher limit.
    Such a requirement would result in the removal of about 600 U.S. 
transport category airplanes at a cost of $7.6 billion or a present 
value of $3.4 billion. The FAA believes this alternative would present 
a substantial burden on industry and adversely affected the wide body 
cargo market. The Sensitivity Studies section of the full regulatory 
evaluation explores this option in more detail.
    The FAA concludes the current proposal is the preferred alternative 
because it has benefits exceeding compliance costs and allows for 
continued operation of airplanes up to the point where maintenance 
actions can no longer ensure that the airplanes are free from 
widespread fatigue damage.

Comments Requested

    We requested industry comment, with quantifiable support, for 
important assumptions made in the regulatory analysis. These comments 
are summarized below.
     We request manufacturers to identify, by airplane model, 
anticipated initial operational limits and if they plan to establish an 
initial operational limit for an airplane model that is higher than the 
existing service goal shown in Appendix 2 of this document.
     We request that operators identify airplane models that 
they desire to operate beyond the service goal identified in Appendix 2 
of this document.
     We request comment on the future operational costs that 
this proposal will add for newly type certificated airplanes.
     We request comment from industry on any new technological 
WFD inspection methods, including costs per individual airplane models.
     We request comments on operators' practice of retiring 
airplanes beyond the service goal identified in Appendix 2 and the 
costs to operators of retiring and replacing airplanes at the service 
goal if the initial operational limit for the airplane is at the 
service goal for that airplane.
     We request comment on the number of components, by 
airplane model, likely to be affected by WFD-related problems. The 
greatest uncertainty with respect to the costs of compliance with the 
rule relates to the number of components for a fuselage type likely to 
be affected by WFD-related problems at or above 100% DSG or ESG.

Benefits of This Rulemaking

    The present value benefits of this proposal consist of $726 million 
of accident prevention benefits and $83 million of detection benefits 
for total present value benefits of $809 million. The detection 
benefits are the benefits resulting from averted accidents and a 
reduction in unscheduled maintenance and repairs that would result from 
this proposal.

Costs of This Rulemaking

    The costs of this proposal are those costs incurred by the airplane 
manufacturers for developing WFD programs, the airplane operators who 
incur the costs of inspection, aircraft retirement, and modifications 
to the airplanes, plus the costs incurred by the FAA.
    The attributable costs of the rule do not include the expense of 
making repairs to structure that has been found to be cracked during 
any inspections resulting from the proposed rule. When any inspection 
procedure identifies a condition that renders the aircraft unairworthy, 
current FAA regulations \8\ mandate actions to restore the aircraft to 
an airworthy condition.
---------------------------------------------------------------------------

    \8\ Sections 43.13, 91.7(a), 121.153(a)(2), and 129.14.
---------------------------------------------------------------------------

    To the extent that the repairs would already be required and 
already be performed under existing regulations, because of an 
operator's continuing responsibility to maintain the airworthiness of 
the aircraft, this assumption may overstate the net additional benefits 
from this rulemaking. This rulemaking is intended to ensure that 
problems are identified more rapidly, but the FAA assumes that all WFD 
problems will ultimately be discovered. The FAA and operators might 
identify WFD issues through other inspections or because of an accident 
in a similar aircraft, and therefore operators will have to make the 
repairs at some point. Accordingly, we request commenters to address 
the appropriate allocation of additional benefits, including, 
specifically, the nature and timing of repairs that would

[[Page 19945]]

be undertaken as a result of this rulemaking.
    The present value cost of this proposal, estimated over the 20-year 
study period, is about $360 million.
    Under the proposal endorsed by the ARAC in 2001, the responsibility 
for developing inspection and modification procedures and for putting 
them into practice was to be borne by airplane operators. The costs of 
the rule were estimated under that assumption. We now estimate that the 
airplane manufacturers would incur approximately 10 percent and 
operators would incur approximately 90 percent of these costs. The 
total costs remain unchanged, however. We believe it is possible that 
the manufacturers' assumption of responsibility for testing and 
development would discover areas where WFD is likely to emerge and may 
reduce the need for preventive inspection and maintenance in other 
areas. The FAA is working with industry to develop compliance 
procedures and welcomes any additional information on the assumptions 
we made in these cost estimates.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes ``* * * as 
a principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
to fit regulatory and informational requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to 
regulation.'' To achieve that principle, the RFA requires agencies to 
solicit and consider flexible regulatory proposals and to explain the 
rationale for their actions. 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 proposed or 
final rule will have a ``significant economic impact on a substantial 
number of small entities.'' If the determination is that it will, the 
agency must prepare a regulatory flexibility analysis, as described in 
the RFA.
    The FAA conducted a complete regulatory flexibility analysis to 
assess the impact on small entities and discussed in detail following 
this initial regulatory evaluation. This rule would affect operators of 
airplanes, in the specified parts of the CFR. For operators, a small 
entity is defined as one with 1,500 or fewer employees.\9\ As there are 
operators that met those criteria for a small business, the FAA 
conducted a small business economic impact assessment to determine if 
the rule would have a significant impact on a substantial number of 
these operators. As a result of the small business economic impact 
assessment the FAA believes that this proposal would result in a 
significant economic impact on a substantial number of small entities. 
A complete discussion is contained in the full regulatory evaluation 
filed separately in the docket.
---------------------------------------------------------------------------

    \9\ 13 CFR Part 121.201, Size Strandards Used to Define Small 
Business Concerns, Sector 48-49 Transportation, Subsector 481 Air 
Transportation.
---------------------------------------------------------------------------

Unfunded Mandates Assessment

    Title II of the Act 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 (adjusted annually for inflation) 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 $120.7 million in lieu of $100 million. This proposed rule does not 
contain such a mandate. The requirements of Title II of the Act 
therefore do not apply.

Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and 
criteria of Executive Order 13132, Federalism. We determined that this 
action would not have a substantial direct effect on the States, on the 
relationship between the national Government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government. We therefore determined that this proposed rule would not 
have federalism implications.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the Administrator, when modifying regulations in Title 
14 of the CFR 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 such regulatory 
distinctions as he or she considers appropriate. Because this proposed 
rule would apply to airplanes operated under parts 121 and 129, it 
could, if adopted, affect intrastate aviation in Alaska. The FAA, 
therefore, specifically requests comments on whether there is 
justification for applying the proposed rule differently to intrastate 
operations in Alaska.

Plain English

    Executive Order 12866 (58 FR 51735, October 4, 1993) requires each 
agency to write regulations that are simple and easy to understand. We 
invite your comments on how to make these proposed regulations easier 
to understand, including answers to questions such as the following:
     Are the requirements in the proposed regulations clearly 
stated?
     Do the proposed regulations contain unnecessary technical 
language or jargon that interferes with their clarity?
     Would the regulations be easier to understand if they were 
divided into more (but shorter) sections?
     Is the description in the preamble helpful in 
understanding the proposed regulations?
    Please send your comments to the address specified in the ADDRESSES 
section.

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 (NEPA) in the absence of extraordinary circumstances. The FAA has 
determined this proposed rulemaking action qualifies for the 
categorical exclusion identified in paragraph 312f and involves no 
extraordinary circumstances.

Regulations That Significantly Affect Energy Supply, Distribution, or 
Use

    The FAA has analyzed this NPRM 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 energy action'' under the executive order because it is 
not a ``significant regulatory action'' under Executive Order 12866, 
and it is not likely to have a significant adverse effect on the 
supply, distribution, or use of energy.

VIII. The Proposed Amendments

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend Chapter 1 of Title 14, Code of Federal 
Regulations, parts 25, 121, and 129, as follows:

[[Page 19946]]

List of Subjects

14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 121

    Air carriers, Aircraft, Aviation Safety, Reporting and 
recordkeeping requirements, Safety, Transportation.

14 CFR Part 129

    Air carriers, Aircraft, Aviation Safety, Reporting and 
recordkeeping requirements.

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

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

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

    2. Amend Sec.  25.1 by adding new paragraphs (c) and (d) to read as 
follows:


Sec.  25.1  Applicability.

* * * * *
    (c) This part also establishes requirements for holders of type 
certificates and changes to those certificates to take actions 
necessary to support the continued airworthiness of transport category 
airplanes.
    (d) This part also establishes requirements for persons seeking 
approval for airplane repairs, alterations, or modifications.
    3. Amend Sec.  25.2 by adding a new paragraph (d) to read as 
follows:


Sec.  25.2  Special retroactive requirements.

* * * * *
    (d) In addition to the requirements of this section, subpart I of 
this part contains requirements that apply to--
    (1) Holders of type certificates and supplemental type 
certificates;
    (2) Applicants for type certificates, amendments to type 
certificates (including service bulletins describing design changes), 
and supplemental type certificates; and
    (3) Persons seeking approval for airplane repairs, alterations, or 
modifications.
    4. 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 (ALS) of the Instructions for Continued 
Airworthiness required by Sec.  25.1529. The initial operational limit, 
stated as a number of total accumulated flight cycles or flight hours, 
established by this section must also be included in the ALS 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 and widespread fatigue damage 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 initial operational limit must be established that corresponds to 
the period of time, stated as a number of total accumulated flight 
cycles or flight hours, 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, and the Airworthiness Limitations section of the 
Instructions for Continued Airworthiness required by Sec.  25.1529 of 
this part specifies 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, 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:
* * * * *
    5. Amend part 25 by adding a new subpart I to read as follows:

Subpart I--Continued Airworthiness and Safety Improvements

Sec.

General

25.1801 Purpose and definition.
25.1803 [Reserved]
25.1805 [Reserved]

Widespread Fatigue Damage

25.1807 Initial operational limit: Widespread Fatigue Damage (WFD).
25.1809 Changes to type certificates: Widespread Fatigue Damage 
(WFD).
25.1811 Extended operational limit: Widespread Fatigue Damage (WFD).
25.1813 Repairs, alterations, and modifications: Widespread Fatigue 
Damage (WFD).

Subpart I--Continued Airworthiness and Safety Improvements

General


Sec.  25.1801  Purpose and definition.

    (a) This subpart establishes requirements for support of the 
continued airworthiness of transport category airplanes. These 
requirements may include performing assessments, developing design 
changes, developing revisions to Instructions for Continued 
Airworthiness, and making necessary documentation available to affected 
persons. This subpart applies to the following persons, as specified in 
each section of this subpart:
    (1) Holders of type certificates and supplemental type 
certificates.
    (2) Applicants for type certificates and changes to type 
certificates (including service bulletins describing design changes). 
Applicants for changes to type certificates must comply with the 
requirements of this subpart in addition to the airworthiness 
requirements determined applicable under Sec.  21.101 of this 
subchapter.
    (3) Persons seeking approval for airplane repairs, alterations, or 
modifications that may affect airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  25.1803  [Reserved]


Sec.  25.1805  [Reserved]

Widespread Fatigue Damage


Sec.  25.1807  Initial operational limit: Widespread Fatigue Damage 
(WFD).

    (a) Applicability. Except as provided in paragraph (i) of this 
section, this

[[Page 19947]]

section applies to transport category airplanes with maximum takeoff 
gross weights greater than 75,000 pounds as approved during the 
original type certification of the airplane. It also applies to those 
airplanes certified with maximum takeoff gross weights of 75,000 pounds 
or less, and later increased to greater than 75,000 pounds by an 
amended type certificate or supplemental type certificate. These 
airplanes are referred to in this section as large transport category 
airplanes.
    (b) Initial operational limit. To preclude WFD from occurring in 
the large transport category airplane fleet, each person identified in 
paragraph (c) of this section must comply with the following 
requirements:
    (1) Perform an evaluation of airplane structural configurations to 
determine when WFD is likely to occur for structure susceptible to 
multiple site damage (MSD) or multiple element damage (MED). The 
airplane structural configurations to be evaluated consist of--
    (i) All model variations and derivatives approved under the type 
certificate; and
    (ii) All structural modifications and replacements, to the airplane 
structural configurations specified in paragraph (b)(1)(i), mandated by 
airworthiness directives as of [effective date of the final rule].
    (2) Using the results from the evaluation performed in paragraph 
(b)(1) of this section, establish an initial operational limit, stated 
as a total number of accumulated flight cycles or flight hours.
    (3) If the initial operational limit depends on performance of 
maintenance actions for which service information has not been mandated 
by airworthiness directive as of [effective date of the final rule], 
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, you must comply with that schedule.
    (4) Unless previously accomplished, establish an Airworthiness 
Limitations section (ALS) for each airplane structural configuration 
evaluated under paragraph (b)(1) and submit it to the FAA Oversight 
Office for approval. The ALS must include a section titled Widespread 
Fatigue Damage (WFD) that incorporates the applicable initial 
operational limit established under paragraph (b)(2) of this section.
    (c) Compliance dates for establishing the initial operational 
limit. The following persons must comply with the requirements of 
paragraph (b) of this section by the specified date.
    (1) Holders of type certificates (TC): no later than December 18, 
2007.
    (2) Applicants for TCs, if the date of application was before 
[effective date of the final rule]: no later than December 18, 2007, or 
the date the certificate is issued, whichever occurs later.
    (3) 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 
December 18, 2007.
    (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: no later than December 18, 2007, or the date the 
certificate is issued, whichever occurs later.
    (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 paragraphs (c) and (h) of 
this section.
    (2) A proposed means of compliance with paragraphs (b)(1) through 
(b)(4) of this section.
    (3) If the proposed means of compliance differs from that described 
in FAA advisory material, a detailed explanation of how the proposed 
means will be shown to comply with this section.
    (4) A proposal for submitting a draft of all compliance items 
required by paragraphs (b) and (g) of this section for review by the 
FAA Oversight Office not less than 60 days before the compliance date 
specified in paragraph (c) or (h) of this section, as applicable.
    (5) A proposal for addressing repairs, alterations, and 
modifications as required by paragraph (g) of this section.
    (6) A proposed process for continuously assessing service 
information related to WFD.
    (7) A proposal for how the initial operational limit 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 (TC): no later than March 18, 
2007.
    (2) Applicants for TCs, if the date of application was before 
[effective date of the final rule]: no later than March 18, 2007.
    (3) Holders of either supplemental type certificates (STC) 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 
March 18, 2007.
    (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 [effective 
date of the final rule]: no later than March 18, 2007.
    (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 was after [effective 
date of the final rule]: no later than March 18, 2007, or within 90 
days after the date of application, whichever occurs later.
    (f) Compliance plan deficiencies. Each affected person must 
implement the compliance plan as approved in compliance with paragraph 
(d) of this section. If either paragraph (f)(1) or (2) of this section 
applies, the affected person must submit a corrected plan to the FAA 
Oversight Office and implement the corrected plan within 30 days after 
such notification.
    (1) The FAA Oversight Office notifies the affected person of 
deficiencies in the proposed compliance plan and how to correct them.
    (2) The FAA Oversight Office notifies the affected person of 
deficiencies in the person's implementation of the plan and how to 
correct them.
    (g) Widespread fatigue damage service information and guidelines. 
Each person identified in paragraph (h) of this section must submit the 
following to the FAA Oversight Office for approval--
    (1) An identification of repairs and modifications described in 
structural repair manuals, service bulletins, and other service 
information and design approvals developed by the person, that may be 
susceptible to WFD along with an evaluation to determine when WFD is 
likely to occur in affected structure susceptible to multiple site 
damage or multiple element damage;
    (2) Service information for maintenance actions that must be 
performed to preclude WFD from occurring before the airplane reaches 
the established initial operational limit, if the evaluation required 
by paragraph

[[Page 19948]]

(g)(1) of this section concludes that WFD is likely to occur before the 
initial operational limit established under paragraph (b) of this 
section; and
    (3) Guidelines for--
    (i) Identifying repairs, alterations, and modifications, other than 
those specified in paragraph (g)(1) of this section, that may be 
susceptible to WFD;
    (ii) Evaluating repairs, alterations, and modifications identified 
in paragraph (g)(3)(i) of this section to determine when WFD is likely 
to occur in affected structure; and
    (iii) Developing service information for maintenance actions that 
must be performed to preclude WFD for those repairs, alterations, and 
modifications identified in paragraph (g)(3)(i) of this section.
    (4) Once approved by the FAA Oversight Office, the documents 
required by this paragraph must be made available to owners and 
operators of affected airplanes subject to this section and to affected 
persons subject to Sec.  25.1809 of this subpart.
    (h) Compliance dates for establishing the service information and 
guidelines. The following persons must comply with the requirements of 
paragraph (g) of this section by the specified date.
    (1) Holders of type certificates (TC): no later than December 18, 
2009.
    (2) Applicants for TCs, if the date of application was before 
[effective date of the final rule]: no later than December 18, 2009, or 
the date the certificate is issued, whichever occurs later.
    (3) Applicants for amendments to TCs that increase maximum takeoff 
gross weights from 75,000 pounds or less, to greater than 75,000 
pounds: no later than December 18, 2009, or the date the certificate is 
issued, whichever occurs later.
    (i) This section does not apply to the following airplane models:
    (1) Bombardier BD-700
    (2) Gulfstream G-V
    (3) Gulfstream G-VSP
    (4) British Aerospace, Aircraft Group and Societe Nationale 
Industrielle Aerospatiale Concorde Type 1


Sec.  25.1809  Changes to type certificates: Widespread Fatigue Damage 
(WFD).

    (a) Applicability. Except as stated in paragraph (b) of this 
section, this section applies to supplemental type certificates (STCs) 
and amendments to type certificates (ATC)--
    (1) For transport category airplanes for which initial operational 
limits are established under Sec.  25.1807 of this subpart; and
    (2) That are identified using the guidelines developed according to 
Sec.  25.1807(g)(3) of this subpart.
    (b) This section does not apply to STCs or ATCs covered by Sec.  
25.1807(c)(3) or (4) of this subpart.
    (c) WFD Evaluation. Each person identified in paragraph (d) of this 
section must do the following:
    (1) Perform an evaluation to determine if any new structure or any 
structure affected by the change is susceptible to WFD and, if so, when 
WFD is likely to occur. This evaluation must be performed using:
    (i) Guidelines specified in Sec.  25.1807(g)(3)(i) and (ii) of this 
subpart; or
    (ii) Guidelines approved by the FAA Oversight Office.
    (2) If the evaluation required by paragraph (c)(1) of this section 
concludes that WFD is likely to occur before the initial operational 
limit, develop the maintenance actions that must be performed to 
preclude WFD from occurring before the airplane reaches the established 
initial operational limit. These maintenance actions must be developed 
using:
    (i) Guidelines specified in Sec.  25.1807(g)(3)(iii) of this 
subpart; or
    (ii) Guidelines approved by the FAA Oversight Office.
    (3) Submit to the FAA Oversight Office for approval the maintenance 
actions required by paragraph (c)(2) of this section. Once approved, 
service information for those actions must be made available to owners 
and operators of affected airplanes subject to this section.
    (d) Compliance dates for evaluating changes to type certificates. 
The following persons must comply with the requirements of paragraph 
(c) of this section by the dates specified.
    (1) Holders of STCs: No later than December 18, 2010.
    (2) Applicants for STCs or for amendments to TCs: no later than 
December 18, 2010, or the date the certificate is issued, whichever 
occurs later.
    (e) Compliance plan. Each person identified in paragraph (f) 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 (d) of this 
section.
    (2) A proposed means of compliance with paragraphs (c)(1) through 
(c)(3) of this section.
    (3) If the proposed means of compliance differs from that described 
in FAA advisory material, a detailed explanation of how the proposed 
means will be shown to comply with this section.
    (4) A proposal for submitting a draft of all compliance items 
required by paragraph (b) of this section, as applicable, for review by 
the FAA Oversight Office not less than 60 days before the compliance 
dates specified in paragraph (d) of this section, as applicable.
    (5) A proposed process for continuously assessing service 
information related to WFD.
    (6) A proposal for how the approved service information will be 
distributed.
    (f) Compliance dates for compliance plans. The following persons 
must submit the compliance plan described in paragraph (e) of this 
section to the FAA Oversight Office by the specified dates.
    (1) Holders of STCs: no later than March 18, 2008.
    (2) Applicants for STCs or amendments to TCs: No later than March 
18, 2008, or within 90 days after the date of application, whichever 
occurs later.
    (g) Compliance plan deficiencies. Each affected person must 
implement the compliance plan as approved in compliance with paragraph 
(e) of this section. If either paragraph (g)(1) or (2) of this section 
applies, the affected person must submit a corrected plan to the FAA 
Oversight Office and implement the corrected plan within 30 days after 
such notification.
    (1) The FAA Oversight Office notifies the affected person of 
deficiencies in the proposed compliance plan and how to correct them.
    (2) The FAA Oversight Office notifies the affected person of 
deficiencies in the person's implementation of the plan and how to 
correct them.


Sec.  25.1811  Extended operational limit: Widespread Fatigue Damage 
(WFD).

    (a) Applicability. Any person may apply to extend an operational 
limit approved under Sec.  25.571 of subpart C, Sec.  25.1807 of this 
subpart, or this section. Extending the operational limit is a major 
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 operational limit. To preclude WFD from occurring in 
the transport category airplane fleet, each person applying for an 
extended operational limit must comply with the following requirements:
    (1) Perform an evaluation of the airplane structural configuration 
to determine when WFD is likely to occur for structure susceptible to 
multiple site damage or multiple element damage. The airplane 
structural configuration to be evaluated consists of--
    (i) All model variations and derivatives approved under the type

[[Page 19949]]

certificate for which approval for an extension is sought; and
    (ii) All structural repairs, alterations, and modifications 
installed on each affected airplane, whether or not required by 
airworthiness directive, up to the date of approval of the extended 
operational limit.
    (2) Using the results from the evaluation performed in paragraph 
(b)(1) of this section, establish an extended operational limit, stated 
as a total number of accumulated flight cycles or flight hours.
    (3) Establish a supplement to the Airworthiness Limitations section 
(ALS) and submit it to the FAA Oversight Office for approval. The 
supplemental ALS must include a section titled Widespread Fatigue 
Damage (WFD) that incorporates the applicable extended operational 
limit established under paragraph (b)(2) of this section.
    (4) 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 operational limit. These maintenance actions must 
be documented as airworthiness limitation items in the ALS and 
submitted to the FAA Oversight Office for approval.


Sec.  25.1813  Repairs, alterations, and modifications: Widespread 
Fatigue Damage (WFD).

    (a) Applicability. This section applies to modifications identified 
according to Sec.  25.1807(g)(1) of this chapter and to repairs, 
alterations, and modifications identified using the guidelines 
developed under Sec.  25.1807(g)(3) of this subpart, that are proposed 
for installation on transport category airplanes with an extended 
operational limit approved under Sec.  25.1811 of this subpart.
    (b) Repairs, alterations, or modification requirements. Each person 
seeking approval for any repair, alteration, or modification must 
comply with the following:
    (1) Perform an evaluation according to the applicable guidelines 
developed under section Sec.  25.1807(g)(3) of this subpart to 
determine if any new structure or any structure affected by the repair, 
alteration, or modification is susceptible to WFD and, if so, when it 
is likely to occur. This evaluation must be performed using those 
guidelines or guidelines approved by the FAA Oversight Office.
    (2) If the evaluation required by paragraph (b)(1) of this section 
concludes that WFD is likely to occur before the extended operational 
limit established under Sec.  25.1811 of this subpart, either--
    (i) Modify the proposed repair, alteration, or modification to 
preclude WFD from occurring before the airplane reaches the extended 
operational limit; or
    (ii) Develop the maintenance actions that must be performed to 
preclude WFD from occurring before the airplane reaches the extended 
operational limit. These maintenance actions must be developed using:
    (A) Guidelines specified in Sec.  25.1807(g)(3)(iii) of this 
subpart; or
    (B) Guidelines approved by the FAA Oversight Office.
    (3) The maintenance actions identified in paragraph (b)(2) of this 
section must be documented as airworthiness limitation items, submitted 
to the FAA Oversight Office for approval, and be made available to 
owners and operators of affected airplanes subject to this section.

Appendix H to Part 25--Instructions for Continued Airworthiness

* * * * *
    6. Amend H25.3 of Appendix H by adding paragraph (h) to read as 
follows:
H25.3 Content
* * * * *
    (h) Guidelines for identifying and evaluating repairs, alterations, 
and modifications to structure that may be susceptible to WFD and 
compromise the ability of the airplane to reach the initial operational 
limit.
    7. Amend H25.4 of Appendix H by revising paragraph (a)(1), adding 
and reserving paragraph (a)(3), 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 procedures 
approved under Sec.  25.571.
* * * * *
    (4) An operational limit, stated as a total number of accumulated 
flight cycles or flight hours, approved under Sec.  25.571 of this 
part.
* * * * *

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

    8. The authority citation for part 121 continues to read:

    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.

    9. Amend Sec.  121.1 by adding a new paragraph (g) to read as 
follows:


Sec.  121.  Applicability.

* * * * *
    (g) This part also establishes requirements for operators to take 
actions to support the continued airworthiness of each airplane.
    10. Amend part 121 by adding subpart AA to read as follows:
Subpart AA--Continued Airworthiness and Safety Improvements
Sec.
121.1101 Purpose and definition.
121.1103-121.1113 [Reserved]
121.1115 Widespread fatigue damage.

Subpart AA--Continued Airworthiness and Safety Improvements


Sec.  121.1101  Purpose and definition.

    (a) This subpart requires persons holding an air carrier or 
operating certificate under part 119 of this chapter to support the 
continued airworthiness of each airplane. These requirements may 
include, but are not limited to, revising the maintenance program, 
incorporating design changes, and incorporating revisions to 
Instructions for Continued Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  121.1103-Sec.  121.1113  [Reserved]


Sec.  121.1115  Widespread fatigue damage.

    (a) Applicability. This section applies to certificate holders 
operating transport category airplanes for which an operational limit 
has been established under Sec.  25.571, Sec.  25.1807, or Sec.  
25.1811 of this chapter.
    (b) Operational limit. No certificate holder may operate an 
airplane identified in paragraph (a) of this section after June 18, 
2008, unless an Airworthiness Limitations section (ALS) approved under 
appendix H to part 25 or Sec.  25.1807 of this chapter is incorporated 
into its maintenance program. The ALS must--

[[Page 19950]]

    (1) Include an operational limit approved under Sec.  25.571 or 
Sec.  25.1807 of this chapter, as applicable, except as provided in 
paragraph (c) of this section; and
    (2) Be clearly distinguishable within its maintenance program.
    (c) Extended operational limit. No certificate holder may operate 
an airplane beyond the operational limit specified in paragraph (b)(1) 
of this section, unless the following conditions are met:
    (1) An ALS must be incorporated into its maintenance program that--
    (i) Includes an extended operational limit and any widespread 
fatigue damage (WFD) airworthiness limitation items (ALIs) approved 
under Sec.  25.1811 of this chapter; and
    (ii) Is approved under Sec.  25.1811 of this chapter;
    (2) Its maintenance program must incorporate the applicable 
guidelines for identifying and evaluating repairs, alterations, and 
modifications that have been developed according to Sec.  
25.1807(g)(3), or other guidelines approved by the FAA Oversight 
Office.
    (3) The extended operational limit, WFD ALIs, and applicable 
guidelines must be clearly distinguishable within its maintenance 
program.
    (d) Repairs, alterations, and modifications. This paragraph applies 
to modifications identified according to Sec.  25.1807(g)(1) of this 
chapter and to repairs, alterations, and modifications identified in 
the applicable guidelines developed according to Sec.  25.1807(g)(3) of 
this chapter, when installed on airplanes operating under an extended 
operational limit. Any certificate holder returning an airplane to 
service after such a repair, alteration, or modification must do the 
actions required by paragraph (d)(1) and (d)(2) of this section. These 
actions are in addition to any other actions and approvals required by 
this chapter.
    (1) Within 90 days after return to service--
    (i) Perform a WFD evaluation of the repair, alteration, or 
modification;
    (ii) Develop any necessary maintenance actions according to Sec.  
25.1813 of this chapter; and
    (iii) Submit the evaluation and proposed maintenance actions to the 
FAA Oversight Office through the Principal Maintenance Inspector for 
approval.
    (2) Within 90 days after approval by the FAA Oversight Office, 
revise the maintenance program to incorporate any WFD ALI approved 
under this section.
    (e) Principal 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.


Sec.  121.368  [Redesignated]

    11. Redesignate Sec.  121.368 as new Sec.  121.1105.


Sec.  121.368  [Reserved]

    12. A new Sec.  121.368 is added and reserved.


Sec.  121.370  [Redesignated]

    13. Redesignate Sec.  121.370 as new Sec.  121.1107.


Sec.  121.370  [Reserved]

    14. A new Sec.  121.370 is added and reserved.


Sec.  121.370a  [Redesignated]

    15. Redesignate Sec.  121.370a as new Sec.  121.1109.


Sec.  121.370a  [Reserved]

    16. A new Sec.  121.370a is added and reserved.

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

    17. 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.

    18. Amend Sec.  129.1 by revising paragraph (b), and adding a new 
paragraph (d) to read as follows:


Sec.  129.1  Applicability and definitions.

* * * * *
    (b) Operations of U.S.-registered aircraft solely outside the 
United States. In addition to the operations specified under paragraph 
(a) of this section, Sec. Sec.  129.14 and 129.20 and subpart B of this 
part also apply to U.S.-registered aircraft operated solely outside the 
United States in common carriage by a foreign air carrier or foreign 
person.
* * * * *
    (d) This part also establishes requirements for a foreign air 
carrier or foreign person to take actions to support the continued 
airworthiness of each airplane.
    19. Amend part 129 by adding subpart A heading to read as set forth 
below, and designating Sec. Sec.  129.1, 129.11, 129.13 through 129.15 
and Sec. Sec.  129.17 through 129.21, and Sec. Sec.  129.23, 129.25, 
129.28, and 129.29 into subpart A to read as follows:

Subpart A--General

* * * * *
    20. Amend part 129 by adding subpart B to read as follows.
Subpart B--Continued Airworthiness and Safety Improvements
Sec.
129.101 Purpose and definition.
129.103-129.113 [Reserved]
129.115 Widespread fatigue damage.

Subpart B--Continued Airworthiness and Safety Improvements


Sec.  129.101  Purpose and definition.

    (a) This subpart requires a foreign air carrier or foreign person 
operating a U.S.-registered airplane in common carriage to support the 
continued airworthiness of each airplane. These requirements may 
include, but are not limited to, revising the maintenance program, 
incorporating design changes, and incorporating revisions to 
Instructions for Continued Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  129.103-Sec.  129.113  [Reserved]


Sec.  129.115  Widespread fatigue damage.

    (a) Applicability. This section applies to foreign air carriers or 
foreign persons operating U.S.-registered transport category airplanes 
for which an operational limit has been established under Sec.  25.571, 
Sec.  25.1807, or Sec.  25.1811 of this chapter.
    (b) Operational limit. No foreign air carrier or foreign person may 
operate a U.S.-registered airplane identified in paragraph (a) of this 
section after June 18, 2008, unless an Airworthiness Limitations 
section (ALS) approved under appendix H to part 25 or Sec.  25.1807 of 
this chapter is incorporated into its maintenance program. The ALS 
must--
    (1) Include an operational limit approved under Sec.  25.571 or 
Sec.  25.1807 of this chapter, as applicable, except as provided in 
paragraph (c) of this section; and
    (2) Be clearly distinguishable within its maintenance program.
    (c) Extended operational limit. No foreign air carrier or foreign 
person may operate an airplane beyond the operational limit specified 
in paragraph (b)(1) of this section, unless the following conditions 
are met:

[[Page 19951]]

    (1) An ALS must be incorporated into its maintenance program that--
    (i) Includes an extended operational limit and any widespread 
fatigue damage (WFD) airworthiness limitation items (ALIs) approved 
under Sec.  25.1811 of this chapter; and
    (ii) Is approved under Sec.  25.1811 of this chapter;
    (2) Its maintenance program must incorporate the applicable 
guidelines for identifying and evaluating repairs, alterations, and 
modifications that have been developed according to Sec.  
25.1807(g)(3), or other guidelines approved by the FAA Oversight 
Office.
    (3) The extended operational limit, WFD ALIs, and applicable 
guidelines must be clearly distinguishable within its maintenance 
program.
    (d) Repairs, alterations, and modifications. This paragraph applies 
to modifications identified according to Sec.  25.1807(g)(1) of this 
chapter and to repairs, alterations, and modifications identified in 
the applicable guidelines developed according to Sec.  25.1807(g)(3) of 
this chapter, when installed on airplanes operating under an extended 
operational limit. Any foreign air carrier or foreign person returning 
an airplane to service after such a repair, alteration, or modification 
must do the actions required by paragraph (d)(1) and (d)(2) of this 
section. These actions are in addition to any other actions and 
approvals required by this chapter.
    (1) Within 90 days after return to service--
    (i) Perform a WFD evaluation of the repair, alteration, or 
modification;
    (ii) Develop any necessary maintenance actions according to Sec.  
25.1813 of this chapter; and
    (iii) Submit the evaluation and proposed maintenance actions to the 
FAA Oversight Office through the Principal Maintenance Inspector or 
cognizant Flight Standards International Field Office for review and 
approval.
    (2) Within 90 days after approval by the FAA Oversight Office, 
revise the maintenance program to incorporate any WFD ALI approved 
under this section.
    (e) Principal 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.


Sec.  129.16  [Redesignated]

    21. Redesignate Sec.  129.16 as new Sec.  129.109.


Sec.  129.16  [Reserved]

    22. A new Sec.  129.16 is added and reserved.


Sec.  129.32  [Redesignated]

    23. Redesignate Sec.  129.32 as new Sec.  129.107.


Sec.  129.32  [Reserved]

    24. A new Sec.  129.32 is added and reserved.


Sec.  129.33  [Redesignated]

    25. Redesignate Sec.  129.33 as new Sec.  129.105.


Sec.  129.33  [Reserved]

    26. A new Sec.  129.33 is added and reserved.

    Issued in Washington, DC on April 11, 2006.
John M. Allen,
Acting Director, Flight Standards Service, Aviation Safety.
Dorenda D. Baker,
Acting Director, Aircraft Certification Service, Aviation Safety.
[FR Doc. 06-3621 Filed 4-17-06; 8:45 am]
BILLING CODE 4910-13-P