Aging Aircraft Program: Widespread Fatigue Damage

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: April 18, 2006 (Volume 71, Number 74)]
[Proposed Rules]
[Page 19927-19951]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18ap06-22]
[[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

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.

[[Page 19931]]

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.
----------------------------------------------------------------------------------------------------------------
* 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

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