Document ID: FAA-2005-21693-0036
Agency: faa
Document Type: Rule
Title: Damage Tolerance Data for Repairs and Alterations
Posted Date: 2007-12-12T05:00Z

[Federal Register: December 12, 2007 (Volume 72, Number 238)]
[Rules and Regulations]               
[Page 70486-70508]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr12de07-3]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 26, 121, and 129

[Docket No. FAA-2005-21693; Amendment Nos. 26-1, 121-337, 129-44]
RIN 2120-AI32

 
Damage Tolerance Data for Repairs and Alterations

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: This final rule requires holders of design approvals to make 
available to operators damage tolerance data for repairs and 
alterations to fatigue critical airplane structure. This rule will 
support operator compliance with the Aging Airplane Safety final rule 
with respect to the requirement to incorporate into the maintenance 
program, a means for addressing the adverse effects repairs and 
alterations may have on fatigue critical structure. The intent of this 
final rule is to ensure the continued airworthiness of fatigue critical 
airplane structure by requiring design approval holders to support 
operator compliance with specified damage tolerance requirements.

DATES: These amendments become effective January 11, 2008.

FOR FURTHER INFORMATION CONTACT: If you have technical questions about 
this action, contact Greg Schneider, ANM-115, Airframe and Cabin 
Safety, Federal Aviation Administration, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356, telephone: (425-227-2116); facsimile (425-227-
1232); e-mail greg.schneider@faa.gov. Direct any legal questions to 
Doug Anderson, ANM-7, Office of Regional Counsel, Federal Aviation 
Administration, 1601 Lind Avenue, SW., Renton, WA 98057-3356; telephone 
(425) 227-2166; facsimile (425) 227-1007; e-mail 
Douglas.Anderson@faa.gov.

SUPPLEMENTARY INFORMATION:

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, Section 106 
describes the

[[Page 70487]]

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.

Table of Contents

I. Executive Summary
II. Background
    A. Summary of the NPRM
    1. The Proposed Rule
    2. Related Activities
    B. Differences Between the NPRM and the Final Rule
    1. New Part 26 for Design Approval Holders' Airworthiness 
Requirements
    2. New Subparts for Airworthiness Operational Rules
    3. Minor Conforming Changes to the Aging Airplane Safety Final 
Rule
    4. Other Miscellaneous Changes
    C. Summary of Comments
III. Discussion of the Final Rule
    A. Overview
    1. Final Rule
    2. Guidance Material
    B. Airplane Applicability and Exceptions
    1. Airplane Certification Amendment Level
    2. Parts 91, 125, and 135 Operations
    3. Exception of Airplanes Not Operating in the U.S. Under Part 
121 or 129
    C. Fatigue Critical Structure (FCS)
    D. Damage Tolerance Evaluation (DTE)
    E. Damage Tolerance Inspections (DTIs)
    F. DT Data for Repairs
    1. Published Repair Data
    2. Effects of Multiple Repairs
    G. Repair Evaluation Guidelines (REGs)
    H. DT Data for Alterations
    I. Required Documentation
    J. Proprietary Data
    K. Compliance Plan
    1. Process for Continuous Assessment of Service Information
    2. Timing of FAA Approval
    L. Harmonization
    1. Foreign Authority Approval of Required Data
    M. Enforcement
    N. Industry and FAA Resources
    O. Compliance Dates
    P. Costs and Benefits
IV. Final Regulatory Evaluation, Regulatory Flexibility 
Determination, International Trade Impact Assessment, and Unfunded 
Mandates Assessment
V. The Amendments

I. Executive Summary

    Fatigue cracking has been a major aviation safety concern for many 
years. Unless detected and repaired, fatigue cracks can grow to the 
point of catastrophic failure. Since 1978 the FAA has required new 
types of airplanes to meet damage tolerance \1\ (DT) requirements to 
ensure their continued airworthiness. Industry has also used this 
method successfully to develop inspection programs for older airplanes. 
Since the 1980s, the FAA has mandated that operators of most large 
transport airplanes carry out these programs.
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    \1\ Damage tolerance (DT) is a method used to evaluate the crack 
growth and residual strength characteristics of structure. Based on 
the results, inspections or other procedures are established as 
necessary to prevent catastrophic failures due to fatigue. Most 
commonly, the maintenance actions developed are directed inspections 
for fatigue cracking.
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    While these programs have been largely effective, industry has not 
carried out DT methods comprehensively. In particular, while these 
programs apply to the airplane ``baseline'' structure (the airplane 
structure as originally manufactured), they often do not apply to 
repairs and alterations.\2\ This omission is important because 
airplanes are subject to many repairs and alterations throughout their 
operational lives. If fatigue cracking occurs in a repaired or altered 
area, the results can be just as catastrophic as if it had occurred in 
the baseline structure.
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    \2\ Various segments of industry use the term ``modification'' 
to define a design change. We consider this term to be synonymous 
with the term ``alteration.'' We use both terms in this rule to mean 
a design change that is made to an airplane.
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    The FAA adopted the Aging Airplane Safety final rule (AASFR) \3\ in 
early 2005. Among other things, the AASFR requires airline operators of 
certain large transport category airplanes \4\ to implement DT-based 
inspection programs for airplane structure; that is, structure 
susceptible to fatigue cracking that could contribute to a catastrophic 
failure. In this final rule, we refer to this structure as ``fatigue 
critical structure.'' Most importantly for this rule, the AASFR 
requires these inspection programs to ``take into account the adverse 
effects repairs, alterations, and modifications may have on fatigue 
cracking and the inspection of this airplane structure.''
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    \3\ 70 FR 5518; February 2, 2005.
    \4\ The rule applies to turbine powered airplane models with a 
maximum type certificated passenger seating capacity of 30 or more, 
or a maximum payload capacity of 7,500 pounds or more.
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    With the AASFR, we now have in place the regulatory means to 
provide for comprehensive implementation of DT methods on all large 
transport airplanes used by air carriers. To carry out these 
requirements fully, however, it is necessary to place corresponding 
requirements on the holders of FAA design approvals for these 
airplanes. Otherwise, the operators may not be able to obtain the data 
and documents they need to comply with the AASFR. As the owners of the 
data for these airplanes, the design approval holders \5\ (DAHs) are in 
the best position to identify the fatigue critical structure and the 
methods and frequency of inspections that may be needed. Therefore, 
this final rule requires DAHs to develop and make available to 
operators the data and documents they need to support compliance with 
the DT requirements of the AASFR.
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    \5\ For purposes of this rule, design approval holders (DAHs) 
are holders of type certificates (TCs) or supplemental type 
certificates (STCs) issued under 14 CFR part 21.
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    Specifically, this final rule requires DAHs to develop and make 
available the following four types of documents to operators:
    (1) Lists of fatigue critical structure (to aid operators in 
identifying repairs and alterations that need to be addressed for DT).
    (2) Damage tolerance inspections to provide operators with the 
necessary inspection times and methods for the following:
     Repair data published by type certificate (TC) holders.\6\
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    \6\ Published repair data are instructions for accomplishing 
repairs, which are published for general use in structural repair 
manuals (SRMs) and service bulletins. These data are approved for 
general application to a particular airplane model or airplane 
configuration.
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     TC holder's future repair data not published for general 
use.\7\
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    \7\ This includes repairs that are developed for individual 
airplanes at the request of an operator. These repairs are often 
complex or unique to a particular airplane or group of airplanes 
experiencing similar damage conditions.
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     Repair data developed by supplemental type certificate 
(STC) holders.
     Alteration data developed by TC and STC holders.
    (3) Damage tolerance evaluation guidelines for all other repairs 
(to enable operators to obtain the necessary damage tolerance 
inspections).
    (4) Implementation schedules (to define the necessary timing for 
performing damage tolerance

[[Page 70488]]

evaluations and developing damage tolerance inspections and for 
incorporating the DT data into the operator's maintenance program).
    This final rule transfers the responsibility for developing DT-
based data from operators to DAHs and, therefore, has minimal to no 
societal costs. The aviation industry as a whole would also benefit 
because DAHs could amortize their development costs for DT data over a 
larger fleet.

II. Background

A. Summary of the NPRM

1. The Proposed Rule
    On April 21, 2006, the FAA published in the Federal Register the 
Notice of proposed rulemaking (NPRM) entitled, Damage Tolerance Data 
for Repairs and Alterations (DAH DT Data NPRM),\8\ which is the basis 
of this final rule.
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    \8\ 71 FR 20574.
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    In the DAH DT Data NPRM, the FAA proposed to require DAHs to 
develop and make available to operators certain damage tolerance (DT) 
data that address the adverse effects repairs, alterations, and 
modifications may have on fatigue critical structure. These data are 
necessary to support operator compliance with the Aging Airplane Safety 
Final Rule (AASFR).\9\ Specifically, we proposed to require DAHs to 
develop and make available to operators the following: (1) Lists of 
fatigue critical structure for baseline and alteration structure; (2) 
Damage tolerance inspections (DTIs) for existing published repair and 
alteration data; (3) DTIs for future repair and alteration data; (4) 
Repair evaluation guidelines (REGs) that include a process for 
conducting airplane surveys, a process for establishing DT Data, and 
implementation schedules for the above actions. In addition, we 
proposed to require DAHs to develop a compliance plan for meeting these 
four requirements and to obtain FAA approval of the plan.
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    \9\ AASFR: 70 FR 5518; February 2, 2005. See also 70 FR 23935; 
May 6, 2005: Aging Airplane Safety; Correcting Amendment.
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    The NPRM contains the background and rationale for this rulemaking 
and, except where we have made revisions in this final rule, you should 
refer to it for that information.
2. Related Activities
    In July 2004, we published the Fuel Tank Safety Compliance 
Extension (Final Rule) and Aging Airplane Program Update (Request for 
Comments),\10\ where we informed the public of our intent to propose 
DAH airworthiness requirements to support certain operational rules. We 
requested comments on our proposal.
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    \10\ 69 FR 45936; July 30, 2004.
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    In December 2002, we published the Aging Airplane Safety Interim 
final rule; request for comments.\11\ In February 2005, we adopted the 
AASFR in which we responded to the comments from the interim rule and 
made some changes to that rule. The February 2005 AASFR requires 
affected operators to include certain damage tolerance inspections and 
procedures in their maintenance programs by December 20, 2010. Today's 
final rule is directly related to the AASFR in that it provides a means 
for operators to get the data and documents they need to comply with 
the AASFR.
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    \11\ 67 FR 72726; December 6, 2002.
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    In July 2005, we published a disposition of comments document,\12\ 
in which we responded to comments to the July 2004 action. Also in July 
2005, we published a policy statement, Safety--A Shared 
Responsibility--New Direction for Addressing Airworthiness Issues for 
Transport Airplanes,\13\ that explains our criteria for adopting DAH 
requirements like those described in this final rule.
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    \12\ 70 FR 40168; July 12, 2005: Fuel Tank Safety Compliance 
Extension (Final Rule) and Aging Airplane Program Update (Request 
for Comments).
    \13\ 70 FR 40166, July 12, 2005 (PS-ANM110-7-12-2005).
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    On April 21, 2006,\14\ along with the NPRM for this rulemaking, we 
published a Notice of Availability (NOA) and request for comments on 
draft AC 120-XX \15\ (Damage Tolerance Inspections for Repairs). This 
AC included guidance related to repairs, which the Aviation Rulemaking 
Advisory Committee's (ARAC) Airworthiness Assurance Working Group 
(AAWG) \16\ developed.
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    \14\ 71 FR 20750.
    \15\ Issued as AC 120-93.
    \16\ AAWG Member Organizations: Boeing Commercial Airplanes, 
Federal Express (FedEx), Airbus, Air Transport Association (ATA), 
American Airlines, British Airways, Continental Airlines, Japan 
Airlines, Northwest Airlines, United Airlines, United Parcel Service 
(UPS), Airborne Express, U.S. Airways, Federal Aviation 
Administration (FAA), and European Aviation Safety Agency (EASA).
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    On July 7, 2006, we published a notice \17\ that granted industry a 
90-day extension to comment on the NPRM; and on February 27, 2007, we 
published a NOA \18\ and request for comments on revised AC 120-XX,\19\ 
which includes guidance from the AAWG on both repairs and alterations.
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    \17\ 71 FR 38541.
    \18\ 72 FR 8834.
    \19\ Issued as AC 120-93.
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B. Differences Between the NPRM and the Final Rule

1. New Part 26 for Design Approval Holders' Airworthiness Requirements
    In the NPRM (and other Aging Airplane Program rules), we placed the 
DAH airworthiness requirements in part 25, subpart I. As we explained 
in the recently adopted Enhanced Airworthiness Program for Airplane 
Systems/Fuel Tank Safety final rule (EAPAS/FTS),\20\ we have placed 
these requirements in new part 26, and we have moved the enabling 
regulations into part 21.\21\ We determined that this was the best 
course of action because it keeps part 25 as strictly airworthiness 
standards for transport category airplanes, thus maintaining 
harmonization and compatibility among the United States, Canada, and 
the European Union regulatory systems. Providing references to part 26 
in part 21 clarifies how the part 26 requirements will address existing 
and future design approvals.
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    \20\ 72 FR 63364; November 8, 2007.
    \21\ Certification Procedures for Products and Parts.
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    In creating new part 26, we renumbered the proposed sections of 
part 25, subpart I and we incorporated the changes discussed in this 
preamble. A table of this renumbering is shown below.
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    \22\ This section, which includes an applicability table for 
part 26, was adopted as part of the EAPAS final rule.
    \23\ These definitions were proposed in Sec.  25.1823(b).

  Table 1.--Relationship of Proposed Part 25 Subpart I to Part 26 Final
                                  Rules
------------------------------------------------------------------------
            Part 26 final rules                   Proposed part 25
------------------------------------------------------------------------
Subpart E--Aging Airplane Safety--Damage    Subpart I--Continued
 Tolerance Data for Repairs and              Airworthiness.
 Alterations.
Sec.   26.5 Applicability table...........  New.\22\
Sec.   26.41 Definitions..................  New.\23\
Sec.   26.43 Holders of and applicants for  Sec.   25.1823 Holders of
 type certificates--Repairs.                 type certificates--Repairs.
Sec.   26.45 Holders of type certificates-- Sec.   25.1825 Holders of
 Alterations and repairs to alterations.     type certificates--
                                             Alterations and repairs to
                                             alterations.
Sec.   26.47 Holders of and applicants for  Sec.   25.1827 Holders of
 a supplemental type certificate--           and applicants for a
 Alterations and repairs to alterations.     supplemental type
                                             certificate--Alterations
                                             and repairs to alterations.

[[Page 70489]]

Sec.   26.49 Compliance Plan..............  Sec.   25.1829 Compliance
                                             Plan.
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2. New Subparts for Airworthiness Operational Rules
    We discussed in the preamble to the proposed rule that we would 
establish new subparts for airworthiness-related operational rules. 
Since there were several other aging airplane proposals (e.g., EAPAS) 
published around the same time, each proposal contained language that 
established the new subparts and redesignated certain sections of those 
rules. We said when any one of those proposals became a final rule, we 
would remove the duplicative provisions that established the new 
subparts and redesignated sections from the other aging airplane rules. 
In the DAH DT Data proposal, we included regulatory text to add 
subparts AA and B (Continued Airworthiness and Safety Improvements) to 
include the airworthiness requirements from parts 121 and 129, 
respectively. We also included regulatory language to redesignate the 
section numbers in parts 121 and 129 that were moved to the new 
subparts. However, since the EAPAS final rule was the first to be 
codified, that final rule adopted subparts AA and B and redesignated 
appropriate sections of parts 121 and 129. Therefore, we have removed 
the duplicative regulatory text from this final rule.
    To aid understanding of our discussion about the DAH DT Data rule 
as it relates to the AASFR, we have indicated below the prior and 
redesignated sections of parts 121 and 129 of the AASFR that include 
DT-related requirements.

------------------------------------------------------------------------
              Prior sections                    Redesignated sections
------------------------------------------------------------------------
Sec.   121.370a...........................  Sec.   121.1109
Sec.   129.16.............................  Sec.   129.109
------------------------------------------------------------------------

3. Minor Conforming Changes to the Aging Airplane Safety Final Rule
    During the rulemaking process for the DAH DT Data rule, the FAA 
determined that minor changes to the AASFR were needed to ensure 
clarity of the two rules. The original wording in Sec. Sec.  121.370a 
and 129.16 (redesignated as Sec. Sec.  121.1109 and 129.109, 
respectively) required that changes to the certificate holder's 
maintenance program (i.e., inclusion of DT-based inspections and 
procedures and any revisions to them) be approved by the Aircraft 
Certification Office (ACO) \24\ or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.
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    \24\ The regulatory text in this rule refers to the ACO or 
office of the Transport Airplane Directorate with oversight 
responsibility for the relevant type certificate or supplemental 
type certificate as the FAA Oversight Office.
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    Although the ACO will approve the documentation that the DAH DT 
Data final rule requires DAHs to submit to the FAA, the DT inspections 
and procedures resulting from this documentation, which certificate 
holders must incorporate into their maintenance programs, should be 
approved by their Principal Maintenance Inspector (PMI). Therefore, we 
revised Sec. Sec.  121.1109 and 129.109 to state that it is the PMI's 
responsibility to review and approve changes to a certificate holder's 
maintenance program.
    Also, we believe the requirements in current Sec. Sec.  
121.1109(c)(1) and 129.109(b)(1) that address DT relative to baseline 
structure and repairs, alterations, and modifications would be clearer 
if they were in separate paragraphs. Therefore, we revised Sec. Sec.  
121.1109 and 129.109 to include requirements related to baseline 
structure in Sec.  121.1109(c)(1) and Sec.  129.109(b)(1) and those 
related to repairs, alterations, and modifications in Sec.  
121.1109(c)(2) and Sec.  129.109(b)(2). We also made minor wording 
changes for clarity and consistency with the new part 26 requirements 
and Advisory Circular (AC) 120-XX,\25\ which describes an acceptable 
means of compliance with the DAH DT Data final rule.
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    \25\ Issued as AC 120-93.
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4. Other Miscellaneous Changes
    Based on comments to the proposed rule, we have revised the final 
rule as summarized below and discussed in more detail under the 
Discussion of the Final Rule heading.
    We extended the compliance times for DAHs to develop the required 
lists of fatigue critical structure. For TC holders, we extended the 
compliance date for them to submit their lists of fatigue critical 
baseline structure to the FAA Oversight Office for review and approval 
from 90 to 180 days after the effective date of the final rule. We also 
added a provision that makes it clear to future TC holders that the 
lists of fatigue critical baseline structure must be submitted as part 
of the type certification process.
    In the NPRM, we proposed TC holders submit their lists of fatigue 
critical alteration structure to the FAA Oversight Office for review 
and approval 90 days after the effective date of the final rule. We 
proposed 270 days for STC holders. In the final rule, we extended the 
compliance date to 360 days after the effective date of the final rule 
for both TC holders and STC holders to submit these lists.
    The NPRM included a requirement for TC and STC holders to develop a 
process to enable operators to ``establish'' damage tolerance 
inspections (DTIs) for repairs and alterations to fatigue critical 
baseline structure (FCBS). This final rule replaces the term 
``establish'' with ``obtain.'' We made this change because the term 
``obtain'' better reflects the intent of the rule and is meant to be 
all inclusive. That is, the operator may ``obtain'' a DTI by 
establishing it themselves, or by receiving the DTI directly from a TC 
holder, STC holder, or a third party.
    Section 25.1823(f)(1)(iii) (adopted as Sec.  26.43(e)(1)(iii)) 
proposed an implementation schedule for repairs covered by the repair 
evaluation guidelines (REGs). To clarify this proposed requirement, we 
revised it in the final rule to specify that the implementation 
schedule must identify the times when actions must be taken as specific 
numbers of flight cycles, flight hours, or both.
    We revised proposed Sec.  25.1823(f)(3) (adopted as Sec.  
26.43(e)(3)) to remove the reference to Sec.  25.1827. That reference 
would have required TC holders to make their REGs available to STC 
holders. We made this change because TC holders do not need to provide 
REGs to STC holders. However, they must provide their lists of fatigue 
critical structure (FCS) to STC holders.
    As discussed in more detail later in this preamble, based on 
comments submitted to other DAH airworthiness rules, we removed some 
provisions of the compliance plan in proposed Sec.  25.1829 (adopted as 
Sec.  26.49). Specifically, we removed the proposed requirements in 
Sec.  25.1829(a)(3) for DAHs to identify the intended means of 
compliance that differ from those described in FAA advisory materials. 
Similarly, we removed the requirement in proposed Sec.  25.1829(c) that 
would have authorized the FAA Oversight Office to identify deficiencies 
in a compliance plan or the DAH's implementation of the plan and to 
require specified corrective actions to remedy those deficiencies. We 
do not

[[Page 70490]]

believe removal of these requirements will adversely affect our ability 
to facilitate DAH compliance.
    In Sec.  25.1829(5), we proposed a requirement for including in the 
compliance plan a process for continuous assessment of service 
information related to structural fatigue damage. As discussed later in 
this preamble, we have determined that existing regulations should 
enable us to determine whether the objectives of this DAH DT Data final 
rule are being met. Therefore, we have removed this provision from this 
final rule.
    In addition to the changes discussed above, we made minor changes 
to clarify the definitions of damage tolerance inspections and 
published repair data in proposed Sec.  25.1823 (the definitions are 
now in Sec.  26.41). We also made other minor changes to clarify the 
requirements in proposed Sec. Sec.  25.1823 (adopted as Sec.  26.43), 
25.1825 (adopted as Sec.  26.45), 25.1827 (adopted as Sec.  26.47), and 
25.1829 (adopted as Sec.  26.49).

C. Summary of Comments

    The FAA received multiple comments from 17 commenters, including 
the Air Transport Association (ATA) and a collective group of certain 
industry representatives who are members of the AAWG.\26\ In the 
following discussion of the comments received to the proposed rule, we 
will refer to the comments received from those industry representatives 
of the AAWG as the ``AAWG industry representatives.'' Also, several of 
the AAWG and the ATA member organizations sent separate comments on 
behalf of their organizations, with some specifically expressing 
support for the comments submitted by the AAWG industry representatives 
and the ATA. The comments to the proposed rule covered an array of 
topics and contained a range of responses, which we discuss more fully 
below under the Discussion of the Final Rule heading. In general, 
commenters supported the intent of the rule and the guidance material. 
They also requested some changes and clarifications.
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    \26\ AAWG industry representatives (a collective group of 
commenters who are members of the AAWG): Boeing Commercial 
Airplanes, Federal Express (FedEx), Airbus, American Airlines, 
British Airways, Continental Airlines, Japan Airlines, Northwest 
Airlines, United Airlines, United Parcel Service (UPS), Airborne 
Express, US Airways.
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    Many of the comments to the proposed rule concerned issues specific 
to the Widespread Fatigue Damage (WFD) \27\ proposal. The FAA intends 
to address the WFD-related comments in a separate action, so we will 
not address them here.
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    \27\ 71 FR 19928; April 18, 2006.
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    We also received several comments about the DAH airworthiness 
requirements. We addressed many of the same or similar comments and 
issues in the July 2005 disposition of comments document to the Fuel 
Tank Safety Compliance Extension (Final Rule) and Aging Airplane 
Program Update (Request for Comments). In addition, we explained in 
detail the need for these requirements in our July 2005 policy 
statement. As a result, we will not revisit those comments and issues 
here.

III. Discussion of the Final Rule

A. Overview

1. Final Rule
    Fatigue cracking has been a major aviation safety concern for many 
years. Unless detected and repaired, fatigue cracks can grow to the 
point of catastrophic failure. Since the adoption of Amendment 25-45 
\28\ in 1978, the FAA has required new types of airplanes to meet 
damage tolerance (DT) requirements to ensure their continued 
airworthiness. Industry has also used this method successfully to 
develop inspection programs for older airplanes, such as Supplemental 
Structural Inspection Programs (SSIP). Since the 1980s, the FAA has 
mandated that operators of most large transport airplanes carry out 
these programs.
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    \28\ 43 FR 46242; October 5, 1978.
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    Although these programs have been effective for baseline structure 
(the airplane structure as originally manufactured), industry has not 
comprehensively implemented DT methods for repairs and alterations. For 
airplanes certified to Amendment 25-45 and later, repairs and 
alterations were not always evaluated for damage tolerance. This 
omission is important because airplanes are subject to many repairs and 
alterations throughout their operational lives. If fatigue cracking 
occurs in a repaired or altered area, the results can be just as 
catastrophic as if it had occurred in the baseline structure.
    The AASFR requires airline operators of certain large transport 
category airplanes \29\ to implement DT-based inspection programs for 
airplane structure; that is, structure susceptible to fatigue cracking 
that could contribute to a catastrophic failure. In today's DAH DT Data 
final rule, we refer to this structure as ``fatigue critical 
structure.'' Most importantly for today's DAH DT Data final rule, the 
AASFR requires the maintenance program for the airplane include a means 
to address the adverse effects repairs and alterations may have on 
airplane structure.
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    \29\ The rule applies to turbine powered airplane models with a 
maximum type certificated passenger seating capacity of 30 more, or 
a maximum payload capacity of 7,500 pounds or more.
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    With the AASFR, we now have in place the regulatory means to 
provide for comprehensive implementation of DT methods on all large 
transport category airplanes used by air carriers operating under 14 
CFR parts 121 and 129. To carry out these requirements fully, however, 
we must place corresponding requirements on the holders of FAA design 
approvals for these airplanes. Otherwise, the operators may not be able 
to obtain the data and documents they need to comply with the AASFR. As 
the owner of the design data for these airplanes, the DAH is in the 
best position to identify the fatigue critical structure and the 
methods and frequency of inspections that may be needed.
    As indicated in our July 2005 policy statement about the shared 
responsibility for addressing airworthiness issues, in cases where 
operators must rely on data or documents from DAHs to comply with 
operational rules, we will require DAHs to develop that information by 
a specified date. This final rule includes such requirements.
    Specifically, 14 CFR 26.43, 26.45, and 26.47 require that the TC 
holders and STC holders develop certain information that will provide a 
means for operators to address the adverse effects of repairs and 
alterations. The information required by this final rule includes the 
following:
     List of Fatigue Critical Structure (baseline and 
alteration).
     Damage tolerance inspections (DTIs) for existing published 
repair data and all future repair data.
     DTIs for all existing and future alteration data.
     Repair evaluation guidelines (REGs), which include--

--Instructions for conducting airplane surveys;
--Instructions an operator uses to obtain DTIs; and
--An implementation schedule that provides timing for the above 
actions.
2. Guidance Material
    The FAA has issued Advisory Circular (AC) 120-93, Damage Tolerance 
of Repairs and Alterations, concurrently with this rule. The AC 
provides TC and STC holders with an acceptable method of compliance 
with this final rule. The AC, which was developed through a 
collaborative effort between the FAA and the Aviation Rulemaking 
Advisory Committee

[[Page 70491]]

(ARAC), supports operator compliance with the AASFR with respect to 
repairs and alterations.
    As amended by this final rule, Sec.  121.1109(c)(2) of the AASFR 
requires operators to incorporate into their maintenance program a 
``means'' for addressing the adverse effects that repairs and 
alterations may have on fatigue critical structure. This AC provides 
guidance that TC holders, STC holders, and operators can use in 
developing a means for addressing repairs and alterations.
    To facilitate operators' timely compliance with the AASFR for 
repairs, the guidance material in this AC includes implementation 
schedules that specify acceptable time frames for when operators can 
incorporate required DT data into their maintenance programs. The 
implementation schedules allow for a phased-in program where existing 
repairs on the older and higher utilization airplanes are assessed 
first, and the newer airplanes assessed as they approach their Design 
Service Goal (DSG). This approach ensures that DTIs will be available 
when needed for both older and newer airplanes.

B. Airplane Applicability and Exceptions

    This rule applies to transport category, turbine powered airplane 
models with an original TC issued after January 1, 1958. With certain 
exceptions, this rule applies to those airplanes that, as a result of 
the original certification or later increase in capacity, have a 
maximum type certificated passenger seating capacity of 30 or more or a 
maximum payload capacity of 7,500 pounds or more. The final rule 
differs from the proposal in that we revised the list of excepted 
airplanes to include the Lockheed L-300, deHavilland DHC-7, and Boeing 
707/720 airplanes. We included these airplanes on the excepted list 
because they are not currently being operated in commercial service in 
the U.S., and we do not expect they will be in the future.
1. Airplane Certification Amendment Level
    Airbus and United Parcel Service (UPS) expressed concern that the 
requirements of this rule duplicate certain requirements of current 
regulations.
    Airbus said because newer airplanes like the A330/A340 and A380 
have a state-of-the-art damage tolerance assessment for all activities 
related to baseline structure, repairs, and alterations, the TC 
holder's activities under proposed Sec. Sec.  25.1823(d) and (e) and 
25.1825(c) and (d) would be ``senseless.'' It said applying the 
proposed requirements to its newer model airplanes would offer no 
additional safety benefit because they are already inherent in the 
consistent application of the damage tolerance requirements in Sec.  
25.571. It also said the proposed activities for these airplane models 
would create an unnecessary administrative burden and would require re-
approval of already DT-justified modifications and repairs. Airbus 
asked the FAA to reconsider applying proposed Sec. Sec.  25.1823 and 
25.1825 to TC holders as they relate to airplane models A330/A340/A380 
and future Airbus models. It suggested addressing this issue under 
proposed Sec.  25.1829 in the model-specific compliance plans.
    UPS said if the proposed rule is adopted, it would force operators 
to survey every airplane in their fleet to find repairs and then 
evaluate them based on guidelines produced by TC holders. UPS believes 
airplanes certified to comply with Amendment 25-54 or later already 
have DT data developed for fatigue critical structure, which includes 
certain baseline structure, as well as all repairs and alterations. UPS 
suggested the FAA make the proposed surveys applicable only to 
airplanes certified prior to Amendment 25-54. To accomplish this, it 
said, the FAA should revise proposed Sec.  25.1823(a) to limit the 
applicability to airplanes type certified to pre-Amendment 25-54 
requirements.
    As discussed in the NPRM, the FAA has identified several airplane 
models certified to Amendment 25-45 or later (including airplane models 
certified to Amendment 25-54) for which published repair data have not 
been evaluated for DT. Therefore, unless accomplished previously, a 
damage tolerance evaluation (DTE) needs to be accomplished for all 
airplanes, regardless of the certification level. For those airplanes 
certified to Amendment 25-45 or later that have had a DTE completed for 
all published repair and alteration data, the compliance plan required 
by Sec.  26.49 (proposed as Sec.  25.1829) should contain a statement 
to that effect, and the TC holder will need to substantiate this 
statement with previously approved data from their certification effort 
to show compliance with this rule. TC holders who have already 
substantiated compliance with DT requirements should not find 
compliance with this rule burdensome.
    Regarding UPS's comment, if the TC holder can substantiate 
compliance for its repairs and alterations, it is still likely that 
operators have installed repairs and alterations that were not designed 
by the TC holder on many airplanes. It is also likely that many of 
these repairs and alterations were not assessed for damage tolerance. 
Therefore, a survey will still be necessary to identify those repairs 
and alterations and to determine if DT data are available to support 
operator compliance with the AASFR.
    Bombardier noted that the proposed rule would apply only to DAHs 
for airplanes currently operated under parts 121 or 129. It said this 
would not change the requirement to maintain damage tolerance for all 
airplanes originally certified as damage tolerant under Sec.  25.571 
(Amendment 45 or later). It said it presumes these airplanes will 
continue to be regulated under Sec.  25.1529, using AC 25.1529-1 as 
guidance (and under Canadian Air Regulations & Airworthiness Manual 
511.34 for Canadian DAHs). Bombardier asserted that the four DAH 
deliverables required by proposed Sec.  25.1823 (lists of fatigue 
critical baseline structure, damage tolerance inspections, damage 
tolerance evaluation guidelines, and implementation schedules) are 
already required under Sec.  25.1529 (with guidance provided in AC 
25.1529-1) and could constitute compliance with the proposed rule.
    We agree that TC holders and others designing repairs and 
alterations for airplanes certificated to Amendment 25-45 or later 
amendments will continue to be required to comply with Sec.  25.1529, 
regardless of the types of operations conducted. For airplanes subject 
to this DAH DT Data rule, DAHs and operators should use the guidance in 
AC 120-93 instead of AC 25.1529-1 for repairs. Because this rule is 
entirely consistent with Sec. Sec.  25.571 and 25.1529, DTIs that 
comply with this rule will also comply with those sections. To the 
extent such data have been developed previously, their compliance will 
be simplified.
2. Parts 91, 125, and 135 Operations
    Transport Canada and Mr. Thomas A. Knott expressed concern that the 
proposed rule only applies to airplanes operated under parts 121 and 
129. Mr. Knott also stated that it leaves out airplanes operated under 
parts 91, 125, and 135. Transport Canada expressed concern that the DAH 
DT Data proposal and the AASFR do not apply to airplanes operated under 
part 125 and would allow airplanes such as the B727 and B747 to operate 
as passenger-carrying airplanes under part 125 without having to meet 
DT or the aging airplane safety requirements.
    As we discussed earlier in this preamble, the purpose of this rule 
is to support parts 121 and 129 operators'

[[Page 70492]]

compliance with the AASFR. For the reasons discussed in the preamble to 
the AASFR, we limited applicability of the DT requirements 
(supplemental inspections) in that rule to certain large transport 
airplanes that are typically operated under parts 121 or 129. For the 
affected airplanes that are operated under parts 91, 125, or 135, their 
utilization is much lower and the risks associated with fatigue damage 
that the AASFR is intended to address is, therefore, also much lower. 
Because of this, we determined it would not be cost-effective to impose 
the AASFR's supplemental inspection requirements on parts 91, 125, or 
135 operators.
3. Exception of Airplanes Not Operating in the U.S. Under Part 121 or 
129
    Viking Air Limited said it owns seven de Havilland heritage 
aircraft, including the DHC-5 Buffalo and DHC-7. Viking Air Limited 
said there are about 23 DHC-5s in confirmed operation, and the DHC-7 
has about 66 in confirmed operation. Many of those in confirmed 
operation are used in military operations and are not subject to part 
121 or 129. According to the FAA Registry, no DHC-5 aircraft are 
presently registered in the U.S. Therefore, Viking proposed that the 
DHC-5 be added as an exception under proposed Sec.  25.1823(h). Viking 
Air Limited also said that for the DHC-7, there presently are the 
following safety measures in place: Canadian Airworthiness Directive 
CF-94-19R1 that mandates a Supplemental Inspection Program; CF-2005-36 
that imposes a Structural Life Limit; and CF-98-03 that mandates the 
Corrosion Prevention and Control Program. With these actions, the DHC-
7, the commenter stated, has already met the intentions of aging 
aircraft initiative for structures.
    The FAA researched its data bases and found that the DHC-5 does not 
have a type certificate issued by the U.S. Therefore, there is no need 
for an exception for the DHC-5 Buffalo. Furthermore, we have determined 
that there are no DHC-7 airplanes currently operated under part 121 or 
U.S.-registered DHC-7 airplanes operated under part 129. For the 
reasons discussed earlier in this preamble, we added the DHC-7, as well 
as the Lockheed L-300 and the Boeing 707/720, to the list of excepted 
airplanes in Sec.  26.43(g) of this final rule.

C. Fatigue Critical Structure (FCS)

    This final rule requires TC and STC holders to evaluate their 
designs for baseline and alteration structure to identify FCS. They 
must also develop lists of FCS and make the lists available to 
operators.
    This final rule defines fatigue critical structure as airplane 
structure that is susceptible to fatigue cracking that could contribute 
to a catastrophic failure, as determined under Sec.  25.571. This is 
structure that may need special maintenance actions to manage the 
threat of fatigue. This would be the case for structure that has the 
potential to develop fatigue cracks that, without intervention, could 
lead to a catastrophic failure. The fatigue evaluations are performed 
to determine if special actions are needed and if so, to provide the 
data needed to define the maintenance action requirements. Fatigue 
critical structure may be part of the baseline structure or part of an 
alteration to the baseline structure. As explained in the NPRM,\30\ by 
referencing Sec.  25.571 in the sentence noted below, we intended to 
rely on the many precedents established in finding compliance with this 
section.

    \30\ 71 FR 20583.
---------------------------------------------------------------------------

    Because of industry's extensive experience in showing compliance 
with the damage tolerance requirements of Sec.  25.571, these key 
terms [e.g., fatigue critical structure] should be readily 
understood and applied.

    To clarify how the criteria of Sec.  25.571 apply within the 
context of this rule, we revised the definition of ``fatigue critical 
structure'' by adding the following language: ``Fatigue critical 
structure includes structure, which, if repaired or altered, could be 
susceptible to fatigue cracking and contribute to a catastrophic 
failure.''
    Airbus, the ATA, and UPS, asked for a more detailed definition of 
fatigue critical structure. They expressed concern that, as proposed, 
the definition is open to varying interpretations, so it may not be 
applied consistently across industry or across different airplane 
models. UPS added that some STC holders do not have experience in 
complying with Sec.  25.571. It asserted, the definition must be clear 
so that it can be interpreted and applied in the same manner across the 
industry.
    The ATA and UPS said the methodology for identifying fatigue 
critical structure should include quantitative criteria for assessing 
the criticality of structural elements, based on a comparison of their 
operational loads to their design limit loads or ultimate loads; and it 
should account for load type and single- and multiple-load paths. Also, 
the ATA said, the methodology should define what ``could contribute'' 
means as stated in the definition of fatigue critical structure. It 
recommended possibly using criteria similar to that in Sec.  25.1309 to 
clarify the definition.
    The term ``fatigue critical structure,'' as explained in the 
proposed rule, is intended to identify the same kind of structure for 
which applicants must perform fatigue evaluations to comply with Sec.  
25.571.\31\ These evaluations have been required for new type 
certificates since the adoption of Amendment 25-45 in 1978. 
Furthermore, AC 25-571-1C, published in 1998, provides many examples of 
the types of structural elements that should be evaluated. Therefore, 
we believe there is little, if any, room for differing interpretations 
of this term.
---------------------------------------------------------------------------

    \31\ Sec.  25.571(a): ``An evaluation of the strength, detail 
design, and fabrication must show that catastrophic failure due to 
fatigue, * * * will be avoided throughout the operational life of 
the airplane. This evaluation must be conducted * * * for each part 
of the structure which could contribute to a catastrophic failure 
(such as wing, empennage, control surfaces, fuselage, engine mounts, 
and their related primary attachments) * * *.''
---------------------------------------------------------------------------

    We believe many of the commenters' concerns result from differences 
in the way industry has used the term ``principal structural elements'' 
(PSEs). This term, as used in Sec.  25.571 and AC 25.571, is synonymous 
with the term ``fatigue critical structure.'' That is, a PSE is 
structure that needs to be evaluated to determine if special 
maintenance actions are needed to manage fatigue. And if such actions 
are needed, they must be defined. The meaning of PSE in Sec.  25.571 
contrasts significantly with its usage in certain industry practices 
that have evolved over the years.
    For some TC and STC holders, a PSE is considered to be a specific, 
localized area within fatigue critical structure where special, 
directed inspections are required by an Airworthiness Directive (AD) or 
airworthiness limitations. For example, all longitudinal skin splices 
in a pressurized fuselage should be considered fatigue critical 
structure if they are not immune to fatigue cracking which could lead 
to a catastrophic failure. However, it may be reasonable to manage 
fatigue in these splices by only performing a special directed 
inspection on the most highly stressed area, which may only constitute 
a small percentage of the at-risk structure.
    Some TC and STC holders have identified the PSE as being limited to 
this localized area. While this narrow usage of the term might be 
acceptable within the context of specific supplemental inspection 
documents (SID) or Airworthiness Limitations Sections (ALS), it could 
and has led to confusion and inappropriate actions when taken out of 
context. For this

[[Page 70493]]

reason, we have chosen not to use the term ``principal structural 
element'' in this rule.
    The purpose of requiring identification and listing of fatigue 
critical structure under this rule is to provide operators with a tool 
that will help in the evaluation of existing and future repairs and 
alterations. In this context, fatigue critical structure (FCS) is any 
structure that, if repaired or altered, could be susceptible to fatigue 
cracking and contribute to a catastrophic failure.
    In the case of the longitudinal skin splices discussed above, we 
would expect that the FCS listed by the TC holder would include much 
more structure than just, for example, the localized area that is being 
inspected to gauge the fatigue state of all the splices. A hypothetical 
repair applied to even the lowest stress area of the splices could 
potentially make it more critical than the highest stressed area 
without a repair by increasing and redistributing structural loads. The 
result would be a repair needing its own special directed inspection to 
prevent potentially catastrophic failure. The only way to cover this 
contingency would be to perform a DTE.
    As discussed above, we revised the proposed definition of FCS to 
clarify how the criteria of Sec.  25.571 apply in the context of this 
rule. As we stated in the NPRM, \32\ we intend for this rule to apply 
to future type certificate holders, as well as current holders. Because 
the list of FCS required by this rule may be more extensive than the 
structure identified as airworthiness limitations items currently 
developed by TC applicants, we added provisions to Sec.  26.43 
paragraphs (a) and (e) to make it clear that the list of FCS must be 
submitted as part of the type certification process. This requirement 
will help ensure that, new TC holders are properly addressing DT 
requirements in developing structural repair manuals (SRMs) and other 
service documents for use by operators. It will also assist operators 
in ensuring that a DTE is performed for all repairs and alterations to 
structure identified as FCS, as required by the AASFR, from the 
beginning of an airplane's operational life.
---------------------------------------------------------------------------

    \32\ 71 FR at 20583.
---------------------------------------------------------------------------

    Regarding the concern that STC holders may not have experience in 
complying with Sec.  25.571, current and earlier versions of AC 25.571-
1C provide guidance on identifying PSEs that is also applicable to 
identification of FCS under this rule. Also, one reason this rule 
requires a compliance plan is to ensure that TC holders, STC holders, 
and the FAA have a common understanding of the rule's requirements, 
including acceptable compliance methods.
    Regarding suggestions to use quantitative methods or methodologies 
used to comply with Sec.  25.1309, our intent is to use the same method 
to identify FCS that is required by Sec.  25.571. Paragraph (a) of 
Sec.  25.571 states that an evaluation must be conducted for ``each 
part of structure that could contribute to a catastrophic failure.'' 
Therefore, the applicant must determine which parts of structure could 
contribute to a catastrophic failure when damaged as a result of 
fatigue cracking. Applying a probabilistic approach to determine if and 
when a part will contribute to a catastrophic failure has not been 
industry practice in complying with Sec.  25.571. TC holders are 
required under Sec.  25.571 to perform a damage tolerance evaluation on 
structure to determine when fatigue cracking may occur. At that point 
an inspection is performed to determine if cracking has occurred. A 
probabilistic approach would raise many implementation questions 
because fatigue cracking in metallic structure is a certainty and 
detection is imperative in order to prevent catastrophic failure of 
airplane structure. Probabilistic approaches would not be consistent 
with our objective of facilitating timely compliance.

D. Damage Tolerance Evaluation (DTE)

    This rule requires TC holders and STC holders to review their 
repair and alteration data and determine if a DTE is needed. Unless 
previously accomplished, a DTE must be performed on all repairs and 
alterations that affect fatigue critical structure. A DTE is a process 
that leads to a determination of maintenance actions necessary to 
detect or preclude fatigue cracking that could contribute to a 
catastrophic failure. As applied to repairs and alterations, a DTE 
includes the evaluation of the repair or alteration and the fatigue 
critical baseline structure affected by the repair or alteration. 
Acceptable methods for performing DTEs are described in AC 25.571-1C.
    The maintenance actions developed as a result of a DTE may include 
inspections, time limits for removal and replacement of repairs, 
modification of the repair, alteration to improve its fatigue 
characteristics, or in some cases modification of the affected FCS. The 
type of maintenance action that is appropriate depends upon the type of 
structure affected and the type of fatigue anticipated. For example, 
for fatigue cracks that grow at a predictable rate and that can be 
detected by inspections, a repetitive inspection program would be 
acceptable. For cracks in locations that cannot be inspected and for 
cracking that may grow too rapidly to be detected reliably, replacement 
or modification may be necessary.
    Section 26.43(c) requires TC holders to perform a DTE of those 
repairs specified in their published repair data that affect fatigue 
critical structure. Similarly, Sec. Sec.  26.45(c) and 26.47(c) require 
TC and STC holders to perform a DTE on their FAA-approved alteration 
data. In addition to the published repair and alteration data, this 
final rule requires that all future repair and alteration data receive 
a DTE to determine if inspections or other actions are necessary to 
ensure the airworthiness of the repair or alteration. This rule also 
requires TC holders to develop Repair Evaluation Guidelines (REGs) that 
will enable operators to survey their airplanes to identify repairs 
that affect fatigue critical baseline structure (FCBS) and to obtain 
any necessary damage tolerance inspections (DTI) for those repairs. If 
the REG directs the operator to obtain assistance from the TC holder 
for developing the DTI, the TC holder must make such assistance 
available.
    As discussed below, based on comments to the NPRM, we revised the 
proposed requirements in Sec. Sec.  25.1825(c) and 25.1827(c) (adopted 
as Sec. Sec.  26.45(c)(1) and 26.47(c)(1), respectively)) to clarify 
that a DTE must be performed and the DTI developed for the alteration 
and the FCBS that is affected by the alteration.
    Boeing and AAWG industry representatives asked that the regulatory 
text in proposed Sec. Sec.  25.1825 and 25.1827 be revised to clarify 
that both alteration and baseline structure need to be assessed. They 
state that the description of the work proposed in these sections of 
the NPRM may be interpreted to mean that DTIs only need to be developed 
for the alteration that happens to affect FCBS. However, AAWG industry 
representatives do not believe this is the interpretation the FAA 
intends. AAWG industry representatives recommended that the language in 
both Sec. Sec.  25.1825 and 25.1827 be changed to clearly say that the 
following three components must be addressed for alterations:

    1. Identification of alterations that affect baseline fatigue 
critical structure.
    2. Identification of the structural design details of the 
alteration that require DTE.
    3. Identification of the affected design details of the baseline 
fatigue critical

[[Page 70494]]

structure that require a re-evaluation of their DTE.

    The commenters are correct in that we did not intend for the 
development of DTIs to be limited to the alteration structure. When a 
DTE is performed for an alteration, the DTE must be applied to both the 
alteration and the FCBS that is affected by the alteration. Therefore, 
the DTI developed (as determined by the DTE) for an alteration would 
apply to the alteration structure and to the FCBS that is affected by 
the alteration. As stated above, we revised Sec. Sec.  25.1825(c) and 
25.1827(c) (adopted as Sec. Sec.  26.45(c)(1) and 26.47(c)(1), 
respectively) to clarify that for the alteration and the FCBS that is 
affected by the alteration a DTE must be performed and the DTI 
developed.
    The FAA does not believe that Sec. Sec.  25.1825(c) and 25.1827(c) 
(adopted as Sec. Sec.  26.45(c) and 26.47(c), respectively) need to be 
revised to clarify that alterations that affect FCBS need to be 
assessed, or to provide clarification on which structural design 
details of an alteration would require a DTE. Sections 25.1825(c)(1) 
(adopted as Sec.  26.45(c)(1)) and 25.1827(c)(1) (adopted as Sec.  
26.47(c)(1)) already specify that a DTE must be performed for 
alterations that affect FCBS. In addition, the structure of the 
alteration that requires development of a DTI will be identified as 
part of a DTE performed on the alteration. The DTI may need to be 
developed for fatigue critical alteration structure or for other 
alteration structure that may affect the FCBS. We expect that this 
identification would be part of the DTE of the alteration.
    Regarding the commenters' position that the proposed rule needs to 
be revised to clarify the design details of the affected FCBS that will 
need a re-evaluation of their DTE, the DTE of an alteration will 
include an evaluation of the FCS that is affected by the alteration. 
Therefore, in performing the evaluation of the affected FCBS, it must 
be determined if new or revised DTIs need to be developed for this 
structure. Such a determination is made as part of a DTE.
    Mr. Thomas A. Knott, P.E., said the proposed rule ``is fine,'' 
except it does not address repairs and modifications done under part 
43. He said there are many alterations and repairs that were not 
approved under an STC or developed by TC holders.
    The FAA acknowledges that there are existing repairs and 
alterations that were developed and installed under 14 CFR part 43 
without involvement by DAHs. This final rule takes into account these 
types of repairs. The guidelines the DAHs are required to develop will 
describe procedures for operators to follow in developing DTIs for 
repairs. For alterations affecting FCS for which no DAH is responsible, 
the AASFR requires operators either to develop the DT data themselves 
or contract for their development. Because there is no DAH for these 
alterations, they may be especially problematic if the installers 
failed to consider the fatigue characteristics of the alterations or 
their effects on the baseline structure. Both repairs and alterations 
will be identified and assessed as part of surveys conducted to support 
compliance with the AASFR.

E. Damage Tolerance Inspections (DTIs)

    A DTI is defined in this final rule as inspections developed as a 
result of a DTE. The DTI includes the location of the airplane 
structure to be inspected, the inspection method, inspection procedures 
that include acceptance and rejection criteria, and the thresholds and 
intervals associated with those inspections. The DTI may also specify a 
time limit when the repair or alteration needs to be replaced. As 
discussed below, this definition reflects minor changes from the one in 
the proposed rule.
    Boeing asked that the FAA revise the definition of DTI. It said the 
phrase ``and corrective maintenance actions'' could be confused with a 
requirement to provide repair instructions or other corrective measures 
for a condition found during an inspection. It said, historically, the 
only instructions provided are how to accomplish the inspection 
contained in the DTI and what action should be taken if the inspection 
could not be accomplished. Therefore, Boeing requested that the phrase 
``and corrective maintenance actions'' be removed from the definition 
and replaced with the phrase, ``or a time limit when the repair needs 
to be replaced, or both.''
    We agree and have revised the definition in the final rule as 
requested. The purpose of this rule is to support operators' 
implementation of damage tolerance inspection programs, as required by 
the AASFR. Operators already have access to information on corrective 
actions in the form of SRMs and other documents that may be necessary 
if the inspections reveal fatigue cracks. Therefore, it is not 
necessary to include the phrase ``and corrective maintenance actions'' 
in the definition of DTI.
    Bombardier asked, with respect to inspections of repairs, that we 
clarify the phrase ``the location of the airplane structure to be 
inspected'' used in the DTI definition. Bombardier said it understands 
this phrase to mean that the DTI should clearly define which regions of 
the repair and underlying structure should be inspected and the NDT 
(non-destructive testing) method to be used in carrying out the 
inspection. It said the DTI should be clearly linked to the repair 
data, which will of itself define the repair location.
    The FAA agrees that the DTI should clearly define the areas of the 
repair and underlying structure that should be inspected and the 
inspection method to be applied. The DTI will be applicable to specific 
repair data that will define the repair location. This approach is the 
same as that currently used by TC holders in developing SRMs to comply 
with Sec.  25.571, Amendment 25-45 and later.

F. DT Data for Repairs

1. Published Repair Data
    This final rule requires TC holders to review their published 
repair data and determine if DT data exist for the repairs or if the DT 
data need to be developed. This final rule defines published repair 
data as instructions for accomplishing repairs, which are published for 
general use in SRMs and service bulletins (or equivalent types of 
documents). As discussed below, we made minor revisions to the proposed 
definition.
    Boeing requested that we revise the definition of ``published 
repair data'' to make it clearer. It recommended the following revised 
version of the proposed definition:

    Published repair data means applicable instructions for 
accomplishing repairs, which are published for general use in 
structural repair manuals and service bulletins (or equivalent types 
of documents).

    The FAA agrees with the recommended revision to the definition of 
``published repair data,'' and we have revised the definition, 
accordingly, with a minor change in wording.
    Bombardier said a list of Structural Significant Items (primary 
structure) is provided in the SRMs for Bombardier Regional Aircraft. It 
urged the FAA to consider rulemaking to require the SRM to be an 
approved document. The SRM, Bombardier commented, can then incorporate 
all of the instructions for continuing airworthiness required by the 
NPRM and described previously in AC 25.1529. It said this approach has 
been used by Bombardier and Transport Canada for SRMs and component 
maintenance manuals (CMMs) applicable to aircraft and components 
certified as damage tolerant to Sec.  25.571 (Amendment 25-45) and 
later.

[[Page 70495]]

    As explained in the NPRM, SRMs, while not required documents, are 
FAA approved. Their purpose is to provide operators with readily 
available sources of approved repair data. Because the operational 
rules require that major repairs be accomplished according to FAA-
approved data, an SRM that has not been FAA approved would not serve 
operators' needs. The SRM, if assessed for damage tolerance under Sec.  
25.571 (Amendment 25-45 or later Amendment), should include the 
necessary instructions to ensure a particular repair meets the criteria 
in AC 25.1529.
2. Effects of Multiple Repairs
    Mr. Glenn Davis commented that DT data should address the effects 
of multiple repairs in close proximity on older aircraft, and future 
inspections should be based on a ``worst case scenario of the 
`combination effect' of the multiple repairs.'' He said the FAA might 
consider requiring a time limit for individual or multiple repairs when 
the repaired structure would have to be replaced, unless the applicant 
or operator can confirm through a rational fatigue analysis, using an 
acceptable fatigue model, that the repaired structure does not need to 
be replaced. Mr. Davis said such a requirement could be applied to high 
stress areas in older aircraft such as pressure bulkheads, door 
apertures, attach fitting support structure for wings, and stabilizers.
    The FAA agrees with Mr. Davis's comment that the DT data, 
specifically the DTE, should take into account the close proximity of 
repairs. AC 25.571-1C provides guidance on determining the effects of 
multiple repairs that are in close proximity. In addition, the repair 
assessment guideline (RAG) documents developed in support of Sec.  
121.370 (redesignated as Sec.  121.1107)\33\ address the effects of 
these types of repairs on the pressure vessel. The FAA believes that 
existing guidance in AC 25-571-1C, along with guidance developed in AC 
120-93, as part of this final rule, adequately addresses this issue.
---------------------------------------------------------------------------

    \33\ Repair Assessment for Pressurized Fuselages final rule (65 
FR 24108; April 25, 2000).
---------------------------------------------------------------------------

G. Repair Evaluation Guidelines (REGs)

    This final rule requires TC holders to develop REGs that include 
processes operators could use to support compliance with Sec. Sec.  
121.1109 and 129.109 for repairs that affect FCBS. The guidelines must 
include--
     A process for conducting surveys of affected airplanes to 
identify and document all existing repairs that affect FCBS;
     A process that will enable operators to obtain DTIs for 
repairs that affect FCBS and for the FCBS affected by the repairs; and
     An implementation schedule that provides the timing for 
conducting airplane surveys and for developing and incorporating DTIs 
into the operator's maintenance program.
    TC holders must submit the REGs to the FAA Oversight Office for 
review and approval and then make them available to affected operators.
    As discussed below, we made several minor revisions to the proposed 
REG requirements.
    In Sec.  25.1823(f)(1)(iii) and (f)(4) (adopted as Sec.  
26.43(e)(1)(iii) and (e)(4)), we removed the term ``DT data'' from the 
phrase ``DT data implementation schedule.'' We made this change because 
the term ``DT data implementation schedule'' may be misunderstood to 
mean the actual timing of DT inspections (thresholds and inspection 
intervals). It was only intended to refer to the timing of major 
process related events (i.e., survey, development of DTIs, and 
incorporation of the DTI into the maintenance program).
    We revised proposed Sec.  25.1823(f)(1)(iii) (adopted as Sec.  
26.43(e)(1)(iii)) to make it clear that the implementation schedule 
must identify the times when actions must be taken as specific numbers 
of flight cycles, flight hours, or both. In developing its 
recommendation regarding implementation schedules, the AAWG proposed an 
approach that would have referenced the design service goal (DSG) for 
determining the timing of various actions and would have allowed for 
variability in DSGs for different airplanes of the same model, 
depending upon actual flight lengths and other factors.
    We agree with the AAWG that it is appropriate to allow reference to 
DSGs in the implementation schedule to allow for industry resources to 
be allocated for compliance when they are needed. For example, the AAWG 
recommended that certain actions be taken when an airplane reaches \3/
4\ DSG, before which fatigue cracking is less likely to have occurred. 
However, allowing variability in DSG for different airplanes of the 
same model would introduce a level of complexity and uncertainty to the 
requirements of the operational rules that would jeopardize their 
enforceability. Therefore, this rule requires that DSGs be stated as 
``hard numbers.''
    We revised Sec.  25.1823(f)(3) (adopted as Sec.  26.43(e)(3)) to 
remove the requirement that TC holders must make REGs available to STC 
holders. As adopted, this paragraph only requires the TC holder to make 
the REGs available to specified operators. We made this change because 
if STC holders have access to the TC holder's list of FCS, they will 
not need their REGs.
    We also revised Sec.  25.1823(f)(4) (adopted as Sec.  26.43(e)(4)). 
The proposed paragraph reads as follows: ``If the guidelines direct the 
operator to obtain assistance from the holder of a type certificate, 
provide such assistance in accordance with * * *'' We revised this 
paragraph in the final rule to replace the words ``provide such 
assistance'' with the words ``make such assistance available.'' This 
change makes it clear that, as with other requirements for TC holders 
to support operators, this rule is not intended to require TC holders 
to provide this support without compensation.
    Boeing said proposed Sec.  25.1823(f)(3) specifies that the TC 
holder will make available the guideline documents to various entities. 
Boeing believes this proposed requirement is in error and the reference 
to proposed Sec.  25.1827 should be removed from Sec.  25.1823. Section 
25.1827 is applicable to holders of and applicants for an STC. In 
reading Sec.  25.1827 and draft AC 120-XX,\34\ Boeing said there is no 
need for third parties to have access to the guidelines developed as 
part of Sec.  25.1823. According to Sec.  25.1827 and AC 120-XX, the 
only data required by an STC holder is the list of fatigue critical 
structure, as stipulated in Sec.  25.1823(c)(2). In light of this, 
Boeing said, the reference to Sec.  25.1827 should be deleted from 
proposed Sec.  25.1823.
---------------------------------------------------------------------------

    \34\ Issued as AC 120-93.
---------------------------------------------------------------------------

    We agree that STC holders do not need the guidelines to comply with 
this final rule as long as they have access to the TC holder's list of 
FCS. We have revised the final rule as discussed above.
    Boeing commented that proposed Sec.  25.1823(f)(4) appears to be 
using incorrect terminology. It said the wording in Sec.  25.1823(f)(4) 
could circumvent the current business practices and established 
relationships between the TC holder and the operator. Boeing requested 
that paragraph (f)(4) be changed as follows:

    If the guidelines direct the operator to obtain assistance from 
the holder of a type certificate, the holder of the type certificate 
will make available such assistance in accordance with the DT data 
implementation schedule.

    It was not our intent to require TC holders to provide assistance 
to operators without compensation. As

[[Page 70496]]

indicated above, we have revised the final rule as the commenter 
requested.
    UPS expressed concern about the effectiveness of the proposed REGs. 
The proposed rule, it said, assumes that practical, cost effective REGs 
are achievable. However, the proposed procedure will be significantly 
more complex than the current Repair Assessment Guideline (RAG) 
documents, which only survey fuselage skin. UPS said the current repair 
assessment of pressurized fuselage skin results in removal and 
replacement of some repairs due to the inability to accurately 
determine the exact repair details. Fuselage skin repairs are 
relatively easy to assess because almost all damage is cut out and one 
side of the repair is accessible for detailed measurements. For other 
structure (e.g., stringers, ribs, spars, frames, shear clips, bathtub 
fitting) the ability to determine hidden repair details may not be 
possible without removing the repair. Consequently, the proposed survey 
method of documenting and establishing DTIs on existing repairs could 
result in a higher than necessary repair replacement frequency. To 
minimize the impact of the DTE of repairs, UPS believes it is vital 
that the FCS be properly identified.
    In response to UPS's concerns about the effectiveness of the 
proposed REGs, the airplane repair survey process was patterned after 
existing RAG documents to minimize the impact of the DTE of repairs. AC 
120-93 provides guidance for performing surveys to identify repairs 
that may affect FCS.
    Regarding UPS's comment that certain structure may be difficult to 
inspect without having to remove the repair, operators should work with 
the TC holder in the Structural Task Group (STG) meetings to ensure an 
efficient process is developed for assessing repairs to minimize the 
unnecessary removal of repairs. The DTE will determine what actions are 
necessary to ensure the continued airworthiness of the affected FCBS. 
Performing DTIs on these airplanes should be no more difficult than 
performing them on airplanes for which repair data already have DTIs 
for compliance with the airplane's certification basis. We agree that 
it is vital that FCS be properly identified. As discussed previously, 
this final rule requires TC holders to apply the same analytical 
methods to create this list that they have applied for many years in 
complying with Sec.  25.571.

H. DT Data for Alterations

    This final rule requires TC holders to perform DTEs, and develop 
DTI, if necessary, for their alterations that affect FCBS. For existing 
alterations, TC holders must submit the DT data for FAA approval by 
June 30, 2009. For future alterations, the DT data are required before 
we approve the alteration data.
    Similarly, STC holders must perform DTEs and develop DTIs for their 
alterations that affect FCBS. In addition to alterations, some STC 
holders must perform DTEs and develop DTIs, if necessary, for repairs 
developed by them that affect any FCS. For existing alterations, STC 
holders must submit the DT data for FAA approval by June 30, 2009. For 
future alterations, the DT data are required before we approve the 
alteration data.
    The sections of the proposal that relate to alterations, 
(Sec. Sec.  25.1825 and 25.1827 (adopted as Sec. Sec.  25.45 and 25.47, 
respectively)) were revised as discussed below to make them clearer. As 
proposed, these sections may be misinterpreted to mean that the TC and 
STC holders need to perform a DTE of their alterations as installed on 
individual airplanes, addressing variations in the configurations of 
these airplanes. Our intent, however, is that they perform a DTE only 
of their alteration design data.
    These sections may also be misinterpreted to mean that DTIs only 
need to be developed for the FCS of the alteration. In addition, as 
stated in the definition of damage tolerance evaluation in proposed 
Sec.  25.1823(b), we intended that the DTE would also apply to the FCBS 
that is affected by the alteration and that the resulting DTI would 
also address the affected baseline structure. To clarify these 
requirements, the final rule specifies that TC and STC holders must, 
for each alteration affecting FCBS, identify and develop DTIs for both 
the FCBS that is affected by the alteration and the fatigue critical 
alteration structure. Other than some additional minor wording changes, 
there are no other changes to the sections of the final rule pertaining 
to alterations.
    The ATA commented that the FAA should limit the number of DTEs 
necessary for alterations. Proposed Sec.  25.1825(c) and Sec.  
25.1827(c) require TC holders to perform a DTE of each existing and 
future alteration and submit DT data for the existing alterations to 
the FAA. These provisions would apply to an impracticable number of 
alterations, according to the commenter. The ATA recommended, 
therefore, that the FAA clarify Sec. Sec.  25.1825(c) and 25.1827(c) to 
stipulate that ``each alteration'' applies to each certificate or 
approval of an alteration rather than each installation.
    The FAA agrees that it would be impracticable for TC or STC holders 
to perform a DTE for alterations as installed on individual airplanes, 
which may contain alterations and repairs that would affect the DTE of 
which the TC or STC holder is unaware. It was not the FAA's intent to 
require TC and STC holders to develop DT data for the actual 
installation of their developed design changes (alterations), but 
rather to require them to perform a DTE of the design changes affecting 
FCBS that are specified in their FAA-approved alteration data. This DTE 
must, however, address the range of airplane configurations on which 
the TC or STC holder showed the alteration is eligible for 
installation. We revised Sec. Sec.  25.1825(c) and 25.1827(c) (adopted 
as Sec. Sec.  26.45(c) and 26.47(c), respectively) to clarify that the 
DAHs are only responsible for performing DTE of their alteration data, 
and not of the alterations as actually installed.

I. Required Documentation

    The ATA said the FAA should define the documents required of DAHs 
as specifically as possible, and the product should be delivered to the 
FAA for certification or approval in a form ready for direct 
installation or incorporation as required by the associated operating 
rule. The ATA said adherence to this recommendation should be 
facilitated by the participation of Structural Task Groups (STG) in the 
development of the DTI and REG. The ATA recommended that the FAA use 
consistent terminology in the final rule and in AC 120-XX,\35\ so they 
clearly describe the documentation and data DAHs must make available to 
operators. It said draft AC 120-XX states that DAHs would provide 
operators with a model-specific ``compliance document.'' The NPRM, 
however, does not discuss the ``compliance document'' referenced in the 
draft AC. Similar to the ATA comment, Horizon Air asked that the rule 
define the specific type of required data that DAHs must make available 
to operators.
---------------------------------------------------------------------------

    \35\ Issued as AC 120-93.
---------------------------------------------------------------------------

    We agree with the ATA that this final rule should clearly identify 
the required data and documents. This final rule requires DAHs to 
develop and make available to operators lists of fatigue critical 
structure, damage tolerance inspections for their alterations and 
repair data (supported by DTE documentation submitted to the FAA), 
repair evaluation guidelines, and implementation schedules.
    Based on the Aviation Rulemaking Advisory Committee's (ARAC)

[[Page 70497]]

recommendations, the FAA developed AC 120-93 to facilitate DAH 
compliance with this rule and operator compliance with the AASFR. This 
AC describes a compliance document that would either contain or 
reference these required documents. Because the compliance dates for 
these documents differ, the DAH would not make the compliance document, 
as a whole, available until the last of these documents is approved.
    As described in the AC, this compliance document would support an 
operator's development of an Operator's Implementation Plan (OIP). The 
OIP would provide the means for addressing the adverse effects of 
repairs and alterations. Once this OIP is approved by the operator's 
principal maintenance inspector (PMI), the operator would comply with 
the AASFR by incorporating the OIP into its maintenance program and 
implementing the OIP by performing surveys of its airplanes, obtaining 
necessary damage tolerance inspections and procedures, and performing 
those inspections and procedures, all in accordance with the approved 
implementation schedule contained in the OIP.
    STGs, working under the auspices of the ARAC's Airworthiness 
Assurance Working Group (AAWG), may be convened to assist TC holders in 
developing airplane model-specific DT data. This rule and AC 120-93 
reflect consistent terminology. The DT data to be developed and made 
available are described in Sec. Sec.  26.43, 26.45, and 26.47 of this 
final rule, as well as in AC 120-93.

J. Proprietary Data

    The ATA said the FAA should work with DAHs to establish a narrow 
and clear definition of proprietary data. DAHs have expressed concerns 
that the proposed requirements could lead to the disclosure of 
proprietary data (e.g., DT documentation). Conversely, operators are 
concerned that restrictive disclosure policies could result in REGs and 
DTIs that are too general to be used without costly and time-consuming 
consultation with the DAH. The ATA recommended that the FAA coordinate 
with DAHs to support a goal for documents that must be ``made 
available'' under the proposal that would allow operators to comply 
autonomously with the DT requirements without consulting with the DAH 
more than absolutely necessary. ATA said the FAA can support this 
recommendation further by providing guidelines to DAHs and STGs to 
ensure that claims of proprietary data are not overstated.
    For many years, the FAA has required DAHs to disclose to affected 
persons information they might otherwise consider proprietary. For 
example, since 1981, DAHs have been required to provide Instructions 
for Continued Airworthiness, including DT data, which DAHs may have 
considered proprietary. However, because we have determined that this 
information is essential to maintaining the airplanes in an airworthy 
condition, we have required DAHs to make it available as a condition 
for obtaining and retaining their certificates. Regarding the 
usefulness of the documents developed by the DAHs, because we expect 
these documents will be developed by DAHs in collaboration with the 
affected operators, we anticipate that the operators will ensure they 
are useful for their intended purposes. FAA technical specialists will 
also be monitoring development of these documents for this purpose.

K. Compliance Plan

    This final rule includes requirements for a compliance plan to 
ensure that affected TC and STC holders produce DT data in a timely 
manner that are acceptable in content and format. Integral to the 
compliance plan are procedures to allow the FAA to monitor progress 
toward compliance. The affected TC and STC holders must submit to the 
FAA Oversight Office on the compliance dates specified in the rule a 
compliance plan that addresses--
     The project schedule for meeting the compliance dates, 
including all major milestones;
     A proposed means of compliance with the requirements to 
develop and make available DT data; and
     A plan to submit to the FAA Oversight Office, not less 
than 60 days before the stated compliance dates, a draft of the 
required compliance items.
    Based on comments submitted to other DAH airworthiness rules, the 
FAA has determined that we can remove some provisions of proposed Sec.  
25.1829 (adopted as Sec.  26.49) without adversely affecting our 
ability to facilitate DAH compliance. Specifically, in Sec.  
25.1829(a)(3), we proposed a requirement for DAHs to identify the 
intended means of compliance that differ from those described in FAA 
advisory materials. While this is still a desirable element of any 
compliance plan, we have concluded that an explicit requirement is 
unnecessary. As with normal type certification planning, we expect that 
DAHs will identify these differences and fully discuss them with the 
FAA Oversight Office early in the compliance period to ensure that 
these differences will ultimately not jeopardize full and timely 
compliance.
    Similarly, Sec.  25.1829(c) contains provisions that would have 
authorized the FAA Oversight Office to identify deficiencies in a 
compliance plan or the DAH's implementation of the plan and to require 
specified corrective actions to remedy those deficiencies. While we 
anticipate that this process will still occur in the event of potential 
non-compliance, we have concluded that it is unnecessary to adopt 
explicit requirements to correct deficiencies.
    Ultimately, DAHs are responsible for submitting compliant documents 
by the dates specified in Sec. Sec.  26.43, 26.45, and 26.47 of this 
final rule. Section 26.49 retains the requirements to submit a 
compliance plan and to implement the approved plan. If the FAA 
Oversight Office determines that the DAH is at risk of not submitting 
compliant documents by the compliance dates because of deficiencies in 
either the compliance plan or the DAH's implementation of the plan, the 
FAA Oversight Office will document the deficiencies and request DAH 
corrective action. Failure to implement proper corrective action under 
these circumstances, while not constituting a separate violation, will 
be considered in determining appropriate enforcement action if the DAH 
ultimately fails to meet the requirements of this section.
    We also added an exception for future TC applicants in Sec.  
26.49(a) to make it clear that these applicants are not required to 
submit a separate compliance plan for the applicable requirements of 
this final rule. These compliance issues should be addressed as part of 
the normal certification plan submitted for any type certificate 
project.
    Section 25.1829(5) included a proposed requirement to include in 
the compliance plan a process for continually assessing service 
information related to structural fatigue damage. We have reconsidered 
this proposed requirement and concluded that existing regulations \36\ 
that require both DAHs and operators to report structural defects 
should be adequate to enable us to determine whether the objectives of 
this final rule are being met. Therefore, we removed this provision 
from the final rule.
---------------------------------------------------------------------------

    \36\ 14 CFR 21.3 and 121.703.
---------------------------------------------------------------------------

1. Process for Continuous Assessment of Service Information
    Bombardier, in its comment on the compliance plan, referred to the 
proposed requirement that the compliance plan must address a process 
for continuous assessment of service information. Bombardier said 
feedback

[[Page 70498]]

from operators on the effectiveness and findings resulting from DT-
based inspections of baseline structure, as well as repairs and 
alterations, may not be adequate to enable them to meet this 
requirement.
    As discussed above, we have removed this provision from this final 
rule since existing regulations will enable us to determine if the 
objectives of this final rule are being met.
2. Timing of FAA Approval
    Airbus expressed concern that the FAA may not have sufficient 
resources to handle approval of compliance plans in a timely manner. 
Therefore, it recommends a thorough review of FAA resources needed for 
this activity before committing to the proposed compliance date.
    FedEx said it understands that the compliance documents must be 
approved by the FAA Aircraft Certification Office (ACO) before they are 
made available to operators, but the proposed rule does not state when 
the documents would be made available to operators. FedEx said the rule 
should include a date by which the FAA would approve the DT data that 
TC and STC holders provide, as well as a date by which the approved 
data will be made available to operators.
    The ATA said the FAA should commit to a schedule for approving the 
DT data from DAHs and implementation plans from operators. It requested 
that the FAA give an estimate of when industry can expect the FAA to 
approve the DT documents and implementation plans, taking into account 
the volume of the submissions.
    We are not including time frames in the regulation for our review 
and approval of the compliance plans and compliance documents. 
Expectations for FAA personnel have been defined in FAA Order 8110.26, 
which directs the Aircraft Certification Service and Flight Standards 
Service in their roles and responsibilities for implementing these 
initiatives. The Order includes expected times for reviewing and 
approving DAH compliance plans, plans to correct deficiencies, and 
draft and final compliance data and documents. To facilitate 
implementation, we will also train affected personnel in their roles 
and responsibilities and provide familiarization with requirements of 
the regulations and associated guidance. However, our ability to 
approve documents, and the timing of our approvals, ultimately depends 
on the quality of the documents submitted by the DAHs and their 
responsiveness if we identify deficiencies.

L. Harmonization

    The AAWG industry representatives, ATA, Boeing, Embraer, and 
Horizon Air commented that the FAA should harmonize the DT Data rule 
with EASA and other national airworthiness authorities. If the rule is 
not harmonized, the AAWG industry representatives expressed concern 
that the FAA's retention of authority to make all necessary compliance 
determinations for foreign DAHs will establish ``a substantial 
precedent that could create a significant challenge to all future 
certification programs.'' The AAWG industry representatives said the 
stated requirements advocate ``a procedure that could permit unilateral 
and potentially arbitrary certification activities at the whim of any 
regulatory authority.''
    Boeing and the ATA said the lack of harmonization will cause 
unnecessary conflicts and complexities between the FAA's and foreign 
authorities' requirements. Boeing said while it is aware that EASA is 
pursuing a similar proposal, EASA may not adopt the same requirements 
as the FAA. Also, Boeing said, having to comply with different 
requirements in the same time frame would cause added complications and 
difficulties with meeting aggressive schedules, and it would result in 
unnecessary, additional work for the FAA.
    Both Boeing and the ATA believe harmonization is a standard of 
excellence that has been achieved over many years of hard work and this 
rule should not interfere with that achievement.
    We agree with the commenters that harmonization of this rule with 
other national authorities is an important objective. We fully expect 
to coordinate with EASA and other authorities on findings of 
compliance. EASA and Transport Canada Civil Aviation (TCCA) have 
participated in the AAWG's development of the AC that will support 
compliance with this final rule. As a follow-on to this activity, EASA 
has proposed the formation of a European Aging Aircraft Working Group 
and has requested participation by the FAA. The FAA plans to support 
this activity with representatives from both the Aircraft Certification 
Service and the Flight Standards Service. There is general agreement 
among the authorities on the need to address DT for repairs and 
alterations and on the approach adopted in this rule.
    The AAWG industry representatives commented that there is the 
potential for creating substantial negative impact in the industry with 
respect to airplane certification sales and transfers between U.S. and 
foreign entities because the proposal has not been harmonized with 
EASA. According to the AAWG industry representatives, the economics of 
this impact has not been accounted for in the regulatory evaluation; 
therefore, the FAA should assure that the final rule is harmonized to 
the extent possible with EASA because of the potential economic issue 
for all parties. The AAWG industry representatives also said it appears 
that the long-term intention of EASA is to harmonize with the U.S. 
requirements by 2008 or 2009. And it said that the implementation time 
scales are different between the two authorities' approaches.
    This rule will not have the negative effects suggested by the 
commenter. In fact, by requiring DAHs to develop and make available the 
data necessary to comply with the AASFR, this rule will facilitate 
compliance for all airplanes, which is a prerequisite for 
transferability. All authorities recognize that harmonization of this 
rule is important in that common requirements will allow expeditious 
transfer of airplanes across borders, and we are working towards that 
objective.
1. Foreign Authority Approval of Required Data
    Airbus commented that the NPRM preamble indicates that the FAA 
cannot accept foreign authority approval for documents under Bilateral 
Agreements because these foreign authorities have not yet adopted a 
similar rule. It said the Joint Aviation Authorities (JAA) issued and 
applied Notice of Proposed Amendment (NPA 20-10) (the European Aviation 
Safety Agency (EASA) updated NPA 20-10 to NPA 05/2006), which addresses 
the same airworthiness issues and incorporates similar technical 
guidance. Moreover, evaluation of repairs, alterations, and 
modifications to DT requirements is state-of-the-art and is approved 
under the EASA regulatory system on a daily basis.
    Airbus also said it will be at a disadvantage by having to deal 
unilaterally with the FAA without the support and involvement of EASA. 
Also, it said it would have to coordinate with the FAA's international 
branch along with several other non-U.S. TC holders. However, U.S. TC 
holders will have a dedicated FAA certification office to work with and 
may be able to use their authorized designees to perform compliance 
related activities.
    According to Airbus, obtaining support from the FAA is especially 
important for proposed Sec. Sec.  25.1823(d) and 25.1825(c) and (d) for 
alteration and

[[Page 70499]]

repair approvals. Therefore, Airbus requested that the FAA include EASA 
in the approval process, such that in the near future the FAA could 
accept the majority of the activities performed by EASA under the 
Bilateral Agreement. In addition, Airbus requested that the FAA give 
non-U.S. TC and STC holders the same level of priority and the same 
allocation of FAA resources as U.S. TC and STC holders. This, Airbus 
said, would help mitigate delays in reaction and approval time.
    Horizon Air said the proposed rule states that data will be 
submitted to the FAA Oversight Office or its properly authorized 
designees. In defining ``authorized designees,'' reference is made only 
to Designated Engineering Representatives (DERs) specifically 
authorized by their supervising ACO.
    Horizon Air also said that currently because of the Bilateral 
Agreement between Transport Canada and the FAA, it is able to 
incorporate DTE and DTI documentation for Bombardier and deHavilland 
airplanes directly into its maintenance program. Under the new rule, it 
appears it would be required to submit the developed repair data to the 
ACO before being able to implement it. Therefore, Horizon Air requested 
that Foreign Authorities, specifically Transport Canada, or their 
designees be included under Bilateral Agreements.
    We recognize the important role other national authorities are 
likely to play in implementation of this rule. In addition to the on-
going efforts to harmonize these requirements, we have been working 
closely with the other national authorities to define appropriate 
roles, responsibilities, and relationships among all affected 
authorities. As discussed in the NPRM, the compliance planning 
provisions are equally important for foreign TC holders, and we expect 
to have mutually agreeable arrangements with their authorities on how 
compliance planning will be overseen. We expect these other authorities 
to play a major role in reviewing their TC holders' compliance plans 
and other required documents, which will enable us to provide timely 
approvals for all affected TC and STC holders, assuming the submitted 
documents comply with the applicable requirements.

M. Enforcement

    Bombardier and UPS expressed concerns about enforcement. Bombardier 
asked what mechanism the FAA would use to impose civil penalties on 
non-U.S. DAHs. UPS said the proposed rule does not state how the FAA 
would handle a DAH that does not complete the damage tolerance 
assessment tasks on time. It is also concerned whether the FAA can 
effectively enforce the intent of these types of provisions.
    The compliance planning provisions of this rule are intended to 
facilitate timely compliance and avoid the need of enforcement for non-
compliance. However, under 49 U.S.C. 46301, the FAA has authority to 
take civil penalty action without regard to nationality of the 
respondent. The FAA's general enforcement policies, which are set forth 
in 14 CFR part 13 and Order 2150.3, will apply to the DAH requirements. 
These general policies provide wide discretion for us to impose 
administrative action, civil penalties (up to $25,000 per violation per 
day) or action against a TC or STC holder's certificate (including 
suspension or revocation).
    If a TC or STC holder is found to be non-compliant, we will 
consider the circumstances of non-compliance before determining an 
appropriate course of action. For example, deliberate violations will 
be treated more severely than inadvertent non-compliance. Any 
enforcement action the FAA may choose to take will be in consideration 
of the circumstances of the violation and defined on a case-by-case 
basis.

N. Industry and FAA Resources

    UPS commented that DT analysis depends on complex methodology and 
data. Because of this, there are very few DERs in the industry that 
have FAA DTE approval authority. UPS suggested it is highly unlikely 
that this methodology and relevant data can be streamlined into an 
approach that is useful and effective. It suggested the FAA establish 
an initiative to authorize additional structures DERs with DTE approval 
authority.
    ABX expressed concern that both industry and the FAA have a 
shortage of specialists in areas related to the rule. It said FAA ACOs 
don't have enough resources to provide the needed support to industry 
in a timely manner. It also said the present delegation requirements in 
the area of DT are unachievable for non-OEM DERs. Therefore, ABX said 
the FAA, with support of the industry, should take the following steps:
     Create different levels of delegation for DTE. If 
necessary, keep the requirements the same for full authority but allow 
DERs with less than required experience to obtain delegation to show 
compliance in specific areas, using previously FAA-approved 
methodology.
     Provide training to DERs and/or call for specific college 
courses that can substitute the experience to facilitate the 
delegation.
     Develop methodologies for DT analysis in the areas that 
are frequently needed by operators and STC holders.
     Postpone any rulemakings until the industry has the 
required tools to comply with the rule in the mandated time frame.
    Recognizing the limited industry and FAA resources available to 
perform and approve DTEs, ARAC has developed guidance material in AC 
120-93 that describes a means of compliance with this rule and the 
AASFR that allows the available resources to focus on the highest 
priority DTEs for repairs. This AC describes an implementation schedule 
with a phased-in approach under which existing repairs on the older and 
higher-utilization airplanes are assessed first (highest risk repairs), 
with newer airplanes being assessed when they approach their design 
service goal (DSG). This approach is similar to that established for 
certain RAGs developed for compliance with Sec.  121.370\37\ 
(redesignated as Sec.  121.1107)). Therefore, we find the 
implementation schedule approach described in AC 120-93 to be a 
rational one. We believe this approach will help ensure that adequate 
industry and FAA resources will be available to support timely 
compliance with this final rule and with the AASFR.
---------------------------------------------------------------------------

    \37\ Special maintenance program requirements.
---------------------------------------------------------------------------

    The FAA agrees that there is a need for an increased number of 
designees having authorization for DT. To address this potential 
problem, the FAA is continuing to hold DER seminars to encourage 
participation by DERs in these programs. DERs can work with their FAA 
Oversight Office to develop a plan that would support expanding their 
authorized delegation to include DT. Due to the complexities associated 
with DT, particularly those related to performing DTEs on repairs and 
alterations, it is necessary to ensure DER candidates have adequate 
experience in performing DT and in analyzing repairs and alterations. 
The current process for obtaining DT-delegated functions requires DER 
applicants to have at least 1 year of experience in performing DTEs. 
This experience is necessary for the FAA to gain a level of confidence 
that the DER, once authorized to perform DT on repairs and alterations, 
will submit DT data that are appropriate and not subject to a need for 
extensive review by the FAA Oversight Office.
    For compliance with the AASFR, it is of particular importance that 
the DERs have a working knowledge of what is required for showing 
compliance with Sec.  25.571 for repairs and alterations. The FAA does 
not agree with the

[[Page 70500]]

commenter's recommendation to allow DER candidates with less than the 
required experience to obtain a delegation for DT, or to substitute the 
requirement for experience with college courses to facilitate 
delegation. Experience is a key element in ensuring the success of the 
FAA's delegation program.
    Regarding the recommendation that the FAA develop methodologies for 
DT analysis in the areas that are frequently needed by operators and 
STC holders, we believe the methodologies employed today, which have 
been used for several years throughout the aviation industry, are 
adequate. Damage-tolerance-based programs such as RAGs developed by TC 
holders to support operator compliance with Sec.  121.370 (redesignated 
as Sec.  121.1107), provide a streamlined approach operators can use 
for assessing repairs common to the airplane pressure boundary. 
Expansion of these guidelines to address additional structural areas 
(e.g., frequently repaired areas), or development of new RAGs, may 
support operator compliance with the AASFR. However, these types of DT-
based programs are model specific and typically require TC holder 
involvement. Operators should coordinate with TC holders during STG 
meetings to determine the need for such programs and how they should be 
structured.
    We disagree with the recommendation to postpone this rulemaking 
because we do not believe industry needs additional time to comply. As 
we have discussed, this final rule is needed to support operator 
compliance with the AASFR. That rule was adopted in February 2005. 
Delaying adoption of the DAH requirements in this rule would adversely 
affect operators' ability to meet the compliance time frame in the 
AASFR. In addition, methodologies for performing a DTE have been 
applied for several years and are readily available. Also, to reduce 
the resource burden, we describe in AC 120-93 an implementation 
schedule that may provide more time for operators to obtain DTEs for 
alterations for which there are no TC or STC holders. This 
implementation schedule may provide, in part, a means for addressing 
the potential adverse effects of alterations.
    UPS said some STC holders may not have the resources (either 
financially, technically, or both) to comply with the proposal. 
Further, it said, the proposal does not address the situation where an 
STC holder has gone out of business or has surrendered its STC to the 
FAA.
    The FAA recognizes that there may be some occasions where the DAH 
is unwilling or unable to comply with the regulations. There may also 
be cases where the DAH no longer exists. As stated in the policy 
statement, Safety--A Shared Responsibility--New Direction for 
Addressing Airworthiness Issues for Transport Category Airplanes, under 
these circumstances, the operator is still obligated to comply with the 
operational rules. However, the FAA recognizes that such occasions may 
significantly complicate the operator's effort to show compliance with 
the operational rules. The FAA recommends the affected operators 
contact their DAHs early in the compliance process to ensure their 
intent to comply. These operators are also encouraged to collaborate 
with other operators who may also be impacted by lack of support on a 
means for compliance.

O. Compliance Dates

    As noted before, today's final rule supports the AASFR, which 
requires operators to incorporate a means to address the adverse 
effects of repairs and alterations into their maintenance program by 
December 20, 2010. This DAH DT Data final rule includes compliance 
dates that require DAHs to make the required DT documents available to 
operators in enough time for them to comply with their approved means 
for addressing repairs and alterations. The approved means will include 
implementation schedules that provide timing for when airplane repair 
surveys are to be performed and when DTI or other maintenance actions 
for repairs and alterations need to be incorporated into the 
maintenance program. Certain of the compliance dates in the DAH DT Data 
final rule have changed from those in the proposed rule.
    Specifically, in proposed Sec.  25.1823(g)(1), TC holders would 
have 90 days after the effective date of the rule to submit their lists 
of fatigue critical baseline structure. In proposed Sec.  
25.1825(e)(1), they would have 90 days to submit their lists of fatigue 
critical alteration structure. In proposed Sec.  25.1827(e)(1), STC 
holders would have 270 days to submit their lists of fatigue critical 
alteration structure.
    In the final rule (Sec.  26.43(f)(1)), TC holders have 180 days 
from the effective date to submit their lists of fatigue critical 
baseline structure. TC and STC holders (Sec. Sec.  26.45(e)(1) and 
26.47(e)(1), respectively) have 360 days from the effective date of the 
rule to submit their lists of fatigue critical alteration structure.
    The AAWG industry representatives, Boeing, FedEx, and Embraer asked 
for an extension of the compliance date in the AASFR and a commensurate 
extension of the DAH DT Data rule's compliance date. While several of 
the commenters acknowledged the FAA's prior 3-year extension (from 2007 
to 2010) to the compliance time for the AASFR, they said if the FAA had 
published the DAH DT Data NPRM at the time of that extension, industry 
would have had more time to comply with the DAH DT Data final rule.
    The AAWG industry representatives asked us to extend the AASFR 
compliance date of December 20, 2010 to December 20, 2013. FedEx asked 
the FAA to give operators a minimum of 12 months after receiving the 
FAA-approved documents to develop their implementation plan to send to 
their FAA Flight Standards District Office. Boeing asked us to extend 
the AASFR compliance date to August 18, 2013. It said the FAA should 
impose incremental compliance times from the effective date of final 
rules, rather than impose a fixed date. For the DAH DT Data final rule, 
Boeing believes the FAA should allow DAHs 4 years from the effective 
date of the rule to submit their documents to the FAA because of the 
addition of the DAH requirements and related compliance plan in this 
final rule.
    Except as discussed previously regarding lists of fatigue critical 
structure (FCS), we do not believe an extension of the compliance dates 
in either rule is appropriate. As several of the commenters 
acknowledged, we previously extended the compliance date for the AASFR 
by 3 years to allow ARAC time to develop guidance material operators 
could use to support compliance with DT requirements related to repairs 
and alterations.
    Based on requests from industry, in May 2004, we tasked \38\ ARAC 
to develop guidance to support operator compliance with the AASFR. 
Included in the tasking notice was a task for ARAC to do the following:
---------------------------------------------------------------------------

    \38\ 69 FR 26641; May 13, 2004.

    Oversee the Structural Task Group (STG) activities that will be 
coordinated for each applicable airplane model by the respective 
type certificate holders and parts 121 and 129 certificate holders. 
These STG activities will involve the development of model specific 
approaches for compliance with Sec. Sec.  121.370a and 129.16 
---------------------------------------------------------------------------
[redesignated as Sec. Sec.  121.1109 and 121.109, respectively]* * *

    In addition, the tasking states that the data developed by the TC 
holders via STG meetings, using the guidance material developed by 
ARAC, should be completed by December 18, 2009. ARAC accepted this 
tasking, which it assigned

[[Page 70501]]

to the AAWG, and agreed to complete it by the specified date of 
December 18, 2009.
    In the February 2005 AASFR, we extended the December 5, 2007 
compliance date adopted in the Aging Airplane Safety Interim final rule 
\39\ to December 20, 2010. This extension was meant to give ARAC time 
to complete the tasking and allow operators a full year to implement 
the resulting program changes. The AAWG developed a schedule for 
completion of the tasking by the agreed-upon date. The compliance dates 
specified in this DAH DT Data final rule are fully consistent with 
these commitments, and none of the commenters have identified reasons 
why we should not expect these commitments to be fulfilled.
---------------------------------------------------------------------------

    \39\ 67 FR 72726; December 6, 2002.
---------------------------------------------------------------------------

    Regarding Boeing's comment that this rule imposes additional 
requirements for which they need more time, assuming ARAC and the STGs 
fulfill their commitments, we anticipate that the products of the 
tasking will enable Boeing and other participating TC holders to meet 
the requirements of this rule with little additional effort. 
Specifically, regarding compliance planning, this type of planning is 
normal business practice, regardless of the requirements of this rule, 
as evidenced by the AAWG's schedule development discussed earlier.
    The ATA, Boeing, UPS, FedEx, and AAWG industry representatives 
asked that DAHs be given 180 days from the effective date of the final 
rule to submit their lists of fatigue critical baseline structure to 
the FAA. The ATA and UPS asked that the FAA allow 360 days from the 
effective date of the final rule for STC holders to submit their lists 
of fatigue critical alteration structure. Airbus requested an extension 
of 1 year from the effective date of the final rule to submit its lists 
of fatigue critical baseline structure. The commenters believe it is 
important to allow DAHs enough time to develop the lists to ensure they 
are accurate.
    Boeing and AAWG industry representatives indicated that the FAA 
should allow additional time to develop the lists because of their 
importance to industry and to other rules like the proposed Widespread 
Fatigue Damage (WFD) rule. Boeing said more time would enable it to 
consult with the STGs on the format and content of the lists. It also 
said more time is needed because of the large numbers of airplanes and 
alterations involved and the need for internal coordination to ensure 
consistency. It estimates that for its airplane models, it would have 
to produce more than 40 lists.
    The ATA, FedEx, and UPS said if DAHs do not have sufficient time to 
develop accurate lists, they may produce overly conservative lists that 
include all primary structure. The ATA and FedEx add that such lists 
would be of little value to operators and would add costs and 
complexities to operator compliance with the AASFR. Also, the ATA said 
DAHs may opt to recommend replacement of structural elements rather 
than inspections and repairs if they do not have enough time to compile 
the lists. Airbus commented that it does not have the resources to 
complete the necessary assessments and compile the lists in the 
proposed time frames. Airbus said the consequence of not having enough 
time to develop accurate lists could be either incomplete lists or 
extremely long lists.
    The FAA believes additional time to establish the lists of fatigue 
critical baseline and alteration structures is appropriate, and has 
revised the rule as discussed above. The revised time frames, which 
give TC holders 180 days to submit their lists of FCBS and TC and STC 
holders 360 days to submit their lists of fatigue critical alteration 
structure, should allow sufficient time to develop the lists. This is 
particularly true since the TC holders have been required to identify 
fatigue critical structure to comply with the damage tolerance 
requirements of Sec.  25.571 since 1978. For pre-amendment 25-45 
airplanes, the TC holder analysis that led to the development of the 
SID documents provide a useful starting point for developing these 
lists. As discussed previously, these activities should already be well 
underway.

P. Costs and Benefits

    The AAWG industry representatives and Boeing commented on our 
statement in the NPRM that the costs of the proposed rule were 
accounted for in the AASFR. The AAWG industry representatives believe 
that the economics on which the proposed rule is based are questionable 
and their basis cannot be determined. Boeing said the FAA assumed that 
much of the work required for compliance with the proposed rule was 
already completed by the TC holders on other programs, such as the SID 
and RAG initiatives. The commenters added that the costs ascribed to 
the TC holder in the proposed rule, in fact, did not exist at the time 
the original rule was published for comment, nor do they exist today.
    The AAWG industry representatives and Boeing requested that the FAA 
revise the basis of the economic evaluation of the proposed rule, and 
include accurate estimates of the cost of the development of compliance 
data by the TC holders, based on the means of compliance suggested in 
AC 120-93.
    The ATA said the FAA should disclose DAH estimates for the cost of 
damage tolerance data and documents. The ATA indicated that it does not 
concur with the FAA's assertion that the proposed rule has minimal to 
no costs. The ATA recommended that the FAA include DAH estimates for 
the cost of these documents in its disposition of comments to the 
proposal.
    UPS said the costs of the proposed rule changes are understated. 
Although the regulatory flexibility analysis in the rulemaking states 
that this rule would relieve small-entity part 121 operators of what 
could be a significant cost, there is nothing in this proposal that 
prevents DAHs from passing all their costs on to the operators. 
Although this compensation could be reasonable, it will also likely be 
significant. UPS suggested that an accurate cost-benefit analysis be 
accomplished and evaluated prior to adopting this rulemaking.
    The requirements to develop damage tolerance (DT) based data for 
repairs and alterations were originally established in the Aging 
Airplane Safety Interim final rule (AASIFR). These responsibilities 
were initially placed on the operators of part 121 and U.S.-registered 
part 129 transport category airplanes. The costs and benefits were 
computed in the regulatory evaluation for that rulemaking. The 
regulatory evaluation for the AASIFR, as well as the regulatory 
evaluation for the AASFR, which clarified these requirements, 
recognized that to comply with the rule's requirements, operators would 
have to develop and implement DT-based inspections and procedures for 
the affected airplane structure. This DAH DT Data final rule is a 
counterpart to the AASFR; it transfers the responsibility of developing 
DT-based data from operators to design approval holders (DAHs). 
Therefore, it has minimal to no societal costs.
    We anticipate that by the compliance date for the AASFR, DT 
inspection programs for baseline structure, required by this DAH DT 
Data final rule, will already be mandated by AD or certification or 
operational regulations for all airplanes affected by this final rule. 
A significant number of operators subject to the AASFR are small 
entities. If each of the small-entity operators individually took the 
responsibility for developing DT-based data, the cost for the data 
would be significant. By transferring the responsibility from part 121 
operators to DAHs, this rule will

[[Page 70502]]

relieve those operators of what could be a significant cost.
    While UPS is correct that operators may have to compensate TC 
holders for the data they make available, we expect these costs to be 
substantially less than if the operators had been required to 
individually develop their own data.
    The DAHs, with their greater expertise and access to design data, 
are in the best position to identify fatigue critical structure and 
methods and frequency of inspections operators need to comply with the 
AASFR. DAHs can develop these data with greater efficiency than 
individual operators and these costs would be amortized over a larger 
fleet. With STG participation, we expect that the resulting compliance 
documents will minimize costs for operators and facilitate their 
compliance with the AASFR. This final rule will ensure that the 
required data are developed in a timely manner to minimize the 
possibility for disruption of airline operations when the AASFR 
compliance deadline is reached. AC 120-93 is largely a product of ARAC 
and reflects industry's view of the most cost effective means for 
developing the data operators must implement under the AASFR.

Paperwork Reduction Act

    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. Information collection 
requirements in the AASFR previously have been approved by the Office 
of Management and Budget (OMB) under the provisions of the Paperwork 
Reduction Act of 1995 (44 U.S.C. 3507(d)) and have been assigned OMB 
Control Numbers: 2120-0020 and 2120-0008. Part 129 record requirements 
can be found in International Civil Aviation Organization Annexes.
    The FAA reviewed data associated with compliance to the AASFR and 
data associated with this rule. We have determined that this rule is a 
transfer of responsibility only, and there is no additional paperwork 
burden on the public. The paperwork burden for compliance with the 
AASFR will be reduced as a result of this rule due to a reduction in 
the numbers of repairs and alterations that will need an individual 
damage tolerance assessment. This is because this rule will require 
design approval holders to develop a streamlined approach for assessing 
repairs.

International Compatibility

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

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

    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 (Pub. L. 96-354) requires 
agencies to analyze the economic impact of regulatory changes on small 
entities. Third, the Trade Agreements Act (Pub. L. 96-39) prohibits 
agencies from setting standards that create unnecessary obstacles to 
the foreign commerce of the United States. In developing U.S. 
standards, the Trade Act requires agencies to consider international 
standards and, where appropriate, that they 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 with base year of 
1995). This portion of the preamble summarizes the FAA's analysis of 
the economic impacts of this final rule.
    Department of Transportation Order DOT 2100.5 prescribes policies 
and procedures for simplification, analysis, and review of regulations. 
If the expected cost impact is so minimal that a proposed or final rule 
does not warrant a full evaluation, this order permits that a statement 
to that effect and the basis for it be included in the preamble if a 
full regulatory evaluation of the cost and benefits is not prepared. 
Such a determination has been made for this final rule. The reasoning 
for this determination follows.
    We begin with a discussion of the AASFR. Then we discuss the 
existing certification and operational rules that already require 
operators to develop and implement the DT inspections and procedures 
this final rule will require.
    This rule transfers the responsibility of developing AASFR DT data 
and documents from operators to DAHs. A transfer of responsibility from 
one entity to another does not increase societal costs; therefore, this 
rule has minimal to no costs. Additionally, the DAH requirements do not 
preclude DAHs from recouping their costs by seeking reasonable 
compensation from the operators for the required DT data and documents. 
The recently published AASFR \40\ requires airline operators of certain 
large transport category airplanes to implement DT-based inspections 
and procedures for airplane structure susceptible to fatigue cracking 
that could contribute to catastrophic failure. Damage tolerance data 
are essential for operators to implement and conduct DT-based 
inspections and procedures.
---------------------------------------------------------------------------

    \40\ 70 FR 5518, February 2, 2005.
---------------------------------------------------------------------------

    This final rule is a counterpart to the AASFR to ensure that 
operators have the necessary data and documents to support timely 
compliance with the requirements of Sec. Sec.  121.1109 and 129.109. 
Timely operator compliance improves the safety of the fleet.
    This final rule will require DAHs to develop DT inspections and 
procedures for repairs and alterations. Existing operational rules 
already require DT inspections and procedures for repairs and 
alterations to baseline structure. TC Holders of airplanes certified to 
Amendment 25-45 (or later), which are affected by this proposal, are 
required by Sec.  25.571 to perform a damage tolerance evaluation and 
establish, as necessary, damage tolerance inspections or other 
procedures. On pre-Amendment 25-45 airplanes, DT inspection and 
procedures for the baseline structure are required by airworthiness 
directive (AD). Damage tolerance inspections for repairs and 
alterations to affected Boeing 727 and 737-100/200 airplanes are also 
required by AD. Damage tolerance inspections for repairs to the 
pressurized fuselage \41\ for certain pre-Amendment 25-45 airplanes 
\42\ are required by Sec.  121.370 (redesignated as Sec.  121.1107). By 
December 2010, damage tolerance inspections for the baseline structure 
and repairs and alterations will be required by Sec. Sec.  121.1109 and 
129.109 for airplanes certificated after January 1, 1958 that have a 
passenger seating

[[Page 70503]]

capacity of 30 or more or a maximum payload capacity of 7500 pounds or 
more. Despite these requirements, in many cases, DT data and documents 
have not yet been developed for many repairs and alterations made to 
the affected airplanes.
---------------------------------------------------------------------------

    \41\ Fuselage, door skins, and bulkhead webs.
    \42\ A-300 (excluding the -600 model), 707, 720, 727, 737-300/
400/500/600/700/800, 747 BAC 1-11, F-28, L-1011, DC-8, DC-9, MD-80, 
and DC-10.
---------------------------------------------------------------------------

    The following table summarizes the regulatory requirements for DT 
inspection programs. The shaded areas in the table represent regulatory 
gaps filled by the AASFR (Sec.  121.1109) requirements to develop DT 
inspections and procedures for fatigue critical airplane structural 
areas.

BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TR12DE07.016

BILLING CODE 4910-13-C
    In  summation, this final rule will transfer the responsibility 
from the existing requirements for developing DT based inspections and 
procedures from part 121 operators to DAHs. The DAHs, with their 
greater expertise and access to design data, are in the best position 
to identify fatigue critical structure and methods and frequency of 
inspections operators need to comply with the

[[Page 70504]]

AASFR. DAHs can develop these data with greater efficiency than 
individual operators and these costs will be amortized over a larger 
fleet. This final rule will ensure that the required data are developed 
in a timely manner to minimize the possibility for disruption of 
airline operations when the AASFR compliance deadline is reached.
---------------------------------------------------------------------------

    \43\ Supplemental Inspection Document.
---------------------------------------------------------------------------

    The FAA has, therefore, determined this rulemaking action is not a 
``significant regulatory action'' as defined in section 3(f) of 
Executive Order 12866, and is not ``significant'' as defined in DOT's 
Regulatory Policies and Procedures. In addition, the FAA has determined 
that this final rulemaking action: (1) Will not have a significant 
economic impact on a substantial number of small entities; (2) will not 
affect international trade; and (3) will not impose an unfunded mandate 
on State, local, or tribal governments, or on the private sector.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) 
establishes ``as a principle of regulatory issuance that agencies shall 
endeavor, consistent with the objectives of the rule and of applicable 
statutes, to fit regulatory and informational requirements to the scale 
of the businesses, organizations, and governmental jurisdictions 
subject to regulation. To achieve this principle, agencies are required 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions to assure that such proposals are given 
serious consideration.'' The RFA covers a wide range of small entities, 
including small businesses, not-for-profit organizations, and small 
governmental jurisdictions.
    Agencies must perform a review to determine whether a rule will 
have a significant economic impact on a substantial number of small 
entities. If the agency determines that it will, the agency must 
prepare a regulatory flexibility analysis as described in the RFA.
    However, if an agency determines that a rule is not expected to 
have a significant economic impact on a substantial number of small 
entities, section 605(b) of the RFA provides that the head of the 
agency may so certify and a regulatory flexibility analysis is not 
required. The certification must include a statement providing the 
factual basis for this determination, and the reasoning should be 
clear.
    We did not receive comments from U.S. small entities in the 
responses to the proposed rule.
    The FAA recently adopted the Aging Airplane Safety Final Rule 
(AASFR),\44\ which, among other things, requires airline operators of 
certain large transport category airplanes \45\ to implement damage 
tolerance (DT) based inspections and procedures for airplane structure.
---------------------------------------------------------------------------

    \44\ 70 FR 5518, February 2, 2005.
    \45\ The rule applies to turbine powered airplane models with a 
maximum type certificated passenger capacity of 30 or more, or a 
maximum payload capacity of 7,500 pounds or more.
---------------------------------------------------------------------------

    This final rule is a counterpart to the AASFR. By the effective 
date of this rule, DT inspection programs will already be required by 
AD, certification or operational regulations for all part 121 airplanes 
affected by this proposal. The final rule will transfer the requirement 
to develop AASFR DT based data for inspections and procedures from part 
121 operators to design approval holders (DAH). A significant number of 
part 121 operators are small entities. By transferring the 
responsibility from part 121 operators to DAH, this final rule may 
relieve small-entity part 121 operators of what could be a significant 
cost.
    DAHs include manufacturers of part 25 airplanes and supplemental 
type certificate (STC) holders for repairs and alterations made to 
these airplanes.
    The current United States part 25 airplane manufacturers include: 
Boeing, Cessna Aircraft, Gulfstream Aerospace, Learjet (owned by 
Bombardier), Lockheed Martin, and Raytheon Aircraft. These 
manufacturers will incur Type Certificate (TC) and Amended TC costs. 
Because all U.S. transport-aircraft category manufacturers have more 
than 1,500 employees, none are considered small entities.
    STC holders include manufacturers and operators of part 25 
airplanes, some of which are small-entities. Since the DAH requirements 
do not preclude them from seeking reasonable compensation from the 
operators for the proposal's required DT data and documents, small-
entities STC holders, with less than 1,500 employees, should be able to 
recoup their costs.
    Therefore, as the Acting FAA Administrator, I certify that this 
rule will not have a significant economic impact on a substantial 
number of small entities.

International Trade Impact Assessment

    The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal 
agencies from establishing any standards or engaging in related 
activities that create unnecessary obstacles to the foreign commerce of 
the United States. Legitimate domestic objectives, such as safety, are 
not considered unnecessary obstacles. The statute also requires 
consideration of international standards and, where appropriate, that 
they be the basis for U.S. standards. The FAA has assessed the 
potential effect of this final rule and determined that it will impose 
the same costs on domestic and international entities and thus has a 
neutral trade impact.

Unfunded Mandate Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement 
assessing the effects of any Federal mandate in a proposed or final 
agency rule that may result in an expenditure of $100 million or more 
(adjusted annually for inflation with the base year 1995) 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 $128.1 million in lieu of $100 million.
    This final rule does not contain such a mandate. The requirements 
of Title II do not apply.

Executive Order 13132, Federalism

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

Environmental Analysis

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

Regulations That Significantly Affect Energy Supply, Distribution, or 
Use

    The FAA has analyzed this final rule under Executive Order 13211, 
Actions Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). We have determined that it is not 
a ``significant energy action'' under Executive Order 12866, and it is 
not

[[Page 70505]]

likely to have a significant adverse effect on the supply, 
distribution, or use of energy.

Availability of Rulemaking Documents

    You can get an electronic copy of rulemaking documents using the 
Internet by--
    1. Searching the Federal eRulemaking Portal (http://www.regulations.gov
);

    2. Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies/
; or

    3. Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.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 amendment number or docket number of this 
rulemaking.
    Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted 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 (Volume 65, Number 70; Pages 19477-78) or you may visit 
http://DocketsInfo.dot.gov.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996 requires FAA to comply with small entity requests for information 
or advice about compliance with statutes and regulations within its 
jurisdiction. If you are a small entity and you have a question 
regarding this document, you may contact your local FAA official, or 
the person listed under the FOR FURTHER INFORMATION CONTACT heading at 
the beginning of the preamble. You can find out more about SBREFA on 
the Internet at http://www.faa.gov/regulations_policies/rulemaking/sbre_act/
.

List of Subjects

14 CFR Part 26

    Aircraft, Aviation safety, Continued airworthiness.

14 CFR Parts 121, 129

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

V. The Amendments

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

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

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

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

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

Sec.  26.5  Applicability table.

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

                                    TABLE 1.--Applicability of Part 26 Rules
----------------------------------------------------------------------------------------------------------------
                                                                   Applicable sections
                                       -------------------------------------------------------------------------
                                               Subpart B (EAPAS/FTS)           Subpart E damage tolerance data
----------------------------------------------------------------------------------------------------------------
Effective Date of Rule................  December 10, 2007..................  January 11, 2008
Existing \1\ TC Holders...............  26.11..............................  26.43, 26.45, 26.49
Pending \1\ TC Applicants.............  26.11..............................  26.43, 26.45
Existing \1\ STC Holders..............  N/A................................  26.47, 26.49
Pending \1\ STC/ATC Applicants........  26.11..............................  26.45, 26.47, 26.49
Future\2\ STC/ATC Applicants..........  26.11..............................  26.45, 26.47, 26.49
Manufacturers.........................  N/A................................  N/A
Persons seeking design approval of      N/A................................  N/A
 repairs.
----------------------------------------------------------------------------------------------------------------
\1\ As of the effective date of the identified rule.
\2\ Application made after the effective date of the identified rule.

0
3. Amend part 26 to add subparts C, D, and E to read as follows:
Subpart C--[Reserved]
Subpart D--[Reserved]
Subpart E--Aging Airplane Safety--Damage Tolerance Data for Repairs and 
Alterations
Sec.
Sec.  26.41 Definitions.
Sec.  26.43 Holders of and applicants for type certificates--
Repairs.
Sec.  26.45 Holders of type certificates--Alterations and repairs to 
alterations.
Sec.  26.47 Holders of and applicants for a supplemental type 
certificate--Alterations and repairs to alterations.
Sec.  26.49 Compliance plan.

Subpart C--[Reserved]

Subpart D--[Reserved]

Subpart E--Aging Airplane Safety--Damage Tolerance Data for Repairs 
and Alterations

Sec.  26.41  Definitions.

    Affects (or Affected) means structure has been physically repaired, 
altered, or modified, or the structural loads acting on the structure 
have been increased or redistributed.
    Baseline structure means structure that is designed under the 
original type certificate or amended type certificate for that airplane 
model.
    Damage Tolerance Evaluation (DTE) means a process that leads to a 
determination of maintenance actions necessary to detect or preclude 
fatigue cracking that could contribute to a catastrophic failure. As 
applied to repairs and alterations, a DTE includes the evaluation both 
of the repair or alteration and of the fatigue critical structure 
affected by the repair or alteration.
    Damage Tolerance Inspection (DTI) means the inspection developed as 
a result of a DTE. A DTI includes the areas to be inspected, the 
inspection method, the inspection procedures, including acceptance and 
rejection criteria, the threshold, and any repeat

[[Page 70506]]

intervals associated with those inspections. The DTI may specify a time 
limit when a repair or alteration needs to be replaced or modified. If 
the DTE concludes that DT-based supplemental structural inspections are 
not necessary, the DTI contains a statement to that effect.
    DT data mean DTE documentation and the DTI.
    DTE documentation means data that identify the evaluated fatigue 
critical structure, the basic assumptions applied in a DTE, and the 
results of a DTE.
    Fatigue critical structure means airplane structure that is 
susceptible to fatigue cracking that could contribute to a catastrophic 
failure, as determined in accordance with Sec.  25.571 of this chapter. 
Fatigue critical structure includes structure, which, if repaired or 
altered, could be susceptible to fatigue cracking and contribute to a 
catastrophic failure. Such structure may be part of the baseline 
structure or part of an alteration.
    Implementation schedule consists of documentation that establishes 
the timing for accomplishing the necessary actions for developing DT 
data for repairs and alterations, and for incorporating those data into 
an operator's continuing airworthiness maintenance program. The 
documentation must identify times when actions must be taken as 
specific numbers of airplane flight hours, flight cycles, or both.
    Published repair data mean instructions for accomplishing repairs, 
which are published for general use in structural repair manuals and 
service bulletins (or equivalent types of documents).

Sec.  26.43  Holders of and applicants for type certificates--Repairs.

    (a) Applicability. Except as specified in paragraph (g) of this 
section, this section applies to transport category, turbine powered 
airplane models with a type certificate issued after January 1, 1958, 
that as a result of original type certification or later increase in 
capacity have--
    (1) A maximum type certificated passenger seating capacity of 30 or 
more; or
    (2) A maximum payload capacity of 7,500 pounds or more.
    (b) List of fatigue critical baseline structure. For airplanes 
specified in paragraph (a) of this section, the holder of or applicant 
for a type certificate must--
    (1) Identify fatigue critical baseline structure for all airplane 
model variations and derivatives approved under the type certificate; 
and
    (2) Develop and submit to the FAA Oversight Office for review and 
approval, a list of the structure identified under paragraph (b)(1) of 
this section and, upon approval, make the list available to persons 
required to comply with Sec.  26.47 and Sec. Sec.  121.1109 and 129.109 
of this chapter.
    (c) Existing and future published repair data. For repair data 
published by a holder of a type certificate that is current as of 
January 11, 2008 and for all later published repair data, the holder of 
a type certificate must--
    (1) Review the repair data and identify each repair specified in 
the data that affects fatigue critical baseline structure identified 
under paragraph (b)(1) of this section;
    (2) Perform a DTE and develop the DTI for each repair identified 
under paragraph (c)(1) of this section, unless previously accomplished;
    (3) Submit the DT data to the FAA Oversight Office or its properly 
authorized designees for review and approval; and
    (4) Upon approval, make the DTI available to persons required to 
comply with Sec. Sec.  121.1109 and 129.109 of this chapter.
    (d) Future repair data not published. For repair data developed by 
a holder of a type certificate that are approved after January 11, 2008 
and are not published, the type certificate holder must accomplish the 
following for repairs specified in the repair data that affect fatigue 
critical baseline structure:
    (1) Perform a DTE and develop the DTI.
    (2) Submit the DT data required in paragraph (d)(1) of this section 
for review and approval by the FAA Oversight Office or its properly 
authorized designees.
    (3) Upon approval, make the approved DTI available to persons 
required to comply with Sec. Sec.  121.1109 and 129.109 of this 
chapter.
    (e) Repair Evaluation Guidelines. The holder of a type certificate 
for each airplane model subject to this section must--
    (1) Develop repair evaluation guidelines for operators' use that 
include--
    (i) A process for conducting surveys of affected airplanes that 
will enable identification and documentation of all existing repairs 
that affect fatigue critical baseline structure identified under 
paragraph (b)(1) of this section and Sec.  26.45(b)(2);
    (ii) A process that will enable operators to obtain the DTI for 
repairs identified under paragraph (e)(1)(i) of this section; and
    (iii) An implementation schedule for repairs covered by the repair 
evaluation guidelines. The implementation schedule must identify times 
when actions must be taken as specific numbers of airplane flight 
hours, flight cycles, or both.
    (2) Submit the repair evaluation guidelines to the FAA Oversight 
Office for review and approval.
    (3) Upon approval, make the guidelines available to persons 
required to comply with Sec. Sec.  121.1109 and 129.109 of this 
chapter.
    (4) If the guidelines direct the operator to obtain assistance from 
the holder of a type certificate, make such assistance available in 
accordance with the implementation schedule.
    (f) Compliance times. Holders of type certificates must submit the 
following to the FAA Oversight Office or its properly authorized 
designees for review and approval by the specified compliance time:
    (1) The identified list of fatigue critical baseline structure 
required by paragraph (b)(2) of this section must be submitted no later 
than 180 days after January 11, 2008 or before issuance of the type 
certificate, whichever occurs later.
    (2) For published repair data that are current as of January 11, 
2008, the DT data required by paragraph (c)(3) of this section must be 
submitted by June 30, 2009.
    (3) For repair data published after January 11, 2008, the DT data 
required by paragraph (c)(3) of this section must be submitted before 
FAA approval of the repair data.
    (4) For unpublished repair data developed after January 11, 2008, 
the DT data required by paragraph (d)(1) of this section must be 
submitted within 12 months of the airplane's return to service or in 
accordance with a schedule approved by the FAA Oversight Office.
    (5) The repair evaluation guidelines required by paragraph (e)(1) 
of this section must be submitted by December 30, 2009.
    (g) Exceptions. The requirements of this section do not apply to 
the following transport category airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Vickers Armstrong Viscount, TCDS No. A-814.
    (3) Douglas DC-3, if modified to include turbine engines, TCDS No. 
A-618.
    (4) Bombardier CL-44, TCDS No. 1A20.
    (5) Mitsubishi YS-11, TCDS No. A1PC.
    (6) British Aerospace BAC 1-11, TCDS No. A5EU.

[[Page 70507]]

    (7) Concorde, TCDS No. A45EU.
    (8) deHavilland D.H. 106 Comet 4C, TCDS No. 7A10.
    (9) deHavilland DHC-7, TCDS No. A20EA.
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614, TCDS No. A39EU.
    (11) Illyushin Aviation IL 96T, TCDS No. A54NM.
    (12) Bristol Aircraft Britannia 305, TCDS No. 7A2.
    (13) Handley Page Herald Type 300, TCDS No. A21N.
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C, TCDS 
No. A40EU.
    (15) Airbus Caravelle, TCDS No. 7A6.
    (16) Lockheed L-300, TCDS No. A2S0.
    (17) Boeing 707-100/-200, TCDS No. 4A21.
    (18) Boeing 707-300/-400, TCDS No. 4A26.
    (19) Boeing 720, TCDS No. 4A28.

Sec.  26.45  Holders of type certificates--Alterations and repairs to 
alterations.

    (a) Applicability. This section applies to transport category 
airplanes subject to Sec.  26.43.
    (b) Fatigue critical alteration structure. For existing and future 
alteration data developed by the holder of a type certificate, the 
holder must--
    (1) Review existing alteration data and identify all alterations 
that affect fatigue critical baseline structure identified under Sec.  
26.43(b)(1);
    (2) For each alteration identified under paragraph (b)(1) of this 
section, identify any fatigue critical alteration structure;
    (3) Develop and submit to the FAA Oversight Office for review and 
approval a list of the structure identified under paragraph (b)(2) of 
this section; and
    (4) Upon approval, make the list required in paragraph (b)(3) of 
this section available to persons required to comply with Sec. Sec.  
121.1109 and 129.109 of this chapter.
    (c) DT Data. For existing and future alteration data developed by 
the holder of a type certificate that affect fatigue critical baseline 
structure identified under Sec.  26.43(b)(1), unless previously 
accomplished, the holder must--
    (1) Perform a DTE and develop the DTI for the alteration and 
fatigue critical baseline structure that is affected by the alteration;
    (2) Submit the DT data developed in accordance with paragraphs 
(c)(1) of this section to the FAA Oversight Office or its properly 
authorized designees for review and approval; and
    (3) Upon approval, make the DTI available to persons required to 
comply with Sec. Sec.  121.1109 and 129.109 of this chapter.
    (d) DT Data for Repairs Made to Alterations. For existing and 
future repair data developed by a holder of a type certificate, the 
type certificate holder must--
    (1) Review the repair data, and identify each repair that affects 
any fatigue critical alteration structure identified under paragraph 
(b)(2) of this section;
    (2) For each repair identified under paragraph (d)(1) of this 
section, unless previously accomplished, perform a DTE and develop DTI;
    (3) Submit the DT data developed in accordance with paragraph 
(d)(2) of this section to the FAA Oversight Office or its properly 
authorized designees for review and approval; and
    (4) Upon approval, make the DTI available to persons required to 
comply with Sec. Sec.  121.1109 and 129.109 of this chapter.
    (e) Compliance times. Holders of type certificates must submit the 
following to the FAA Oversight Office or its properly authorized 
designees for review and approval by the specified compliance time:
    (1) The list of fatigue critical alteration structure identified 
under paragraph (b)(3) of this section must be submitted no later than 
360 days after January 11, 2008.
    (2) For alteration data developed and approved before January 11, 
2008, the DT data required by paragraph (c)(2) of this section must be 
submitted by June 30, 2009.
    (3) For alteration data approved on or after January 11, 2008, DT 
data required by paragraph (c)(2) of this section must be submitted 
before initial approval of the alteration data.
    (4) For repair data developed and approved before January 11, 2008, 
the DT data required by paragraph (d)(2) of this section must be 
submitted by June 30, 2009.
    (5) For repair data developed and approved after January 11, 2008, 
the DT data required by paragraph (d)(2) of this section must be 
submitted within 12 months after initial approval of the repair data 
and before making the DT data available to persons required to comply 
with Sec. Sec.  121.1109 and 129.109 of this chapter.

Sec.  26.47  Holders of and applicants for a supplemental type 
certificate--Alterations and repairs to alterations.

    (a) Applicability. This section applies to transport category 
airplanes subject to Sec.  26.43.
    (b) Fatigue critical alteration structure. For existing structural 
alteration data approved under a supplemental certificate, the holder 
of the supplemental certificate must--
    (1) Review the alteration data and identify all alterations that 
affect fatigue critical baseline structure identified under Sec.  
26.43(b)(1);
    (2) For each alteration identified under paragraph (b)(1) of this 
section, identify any fatigue critical alteration structure;
    (3) Develop and submit to the FAA Oversight Office for review and 
approval a list of the structure identified under paragraph (b)(2) of 
this section; and
    (4) Upon approval, make the list required in paragraph (b)(3) of 
this section available to persons required to comply with Sec. Sec.  
121.1109 and 129.109 of this chapter.
    (c) DT Data. For existing and future alteration data developed by 
the holder of a supplemental type certificate that affect fatigue 
critical baseline structure identified under Sec.  26.43(b)(1), unless 
previously accomplished, the holder of a supplemental type certificate 
must--
    (1) Perform a DTE and develop the DTI for the alteration and 
fatigue critical baseline structure that is affected by the alteration;
    (2) Submit the DT data developed in accordance with paragraphs 
(c)(1) of this section to the FAA Oversight Office or its properly 
authorized designees for review and approval; and
    (3) Upon approval, make the DTI available to persons required to 
comply with Sec. Sec.  121.1109 and 129.109 of this chapter.
    (d) DT Data for Repairs Made to Alterations. For existing and 
future repair data developed by the holder of a supplemental holder of 
a supplemental type certificate, the holder of a supplemental type 
certificate must--
    (1) Review the repair data, and identify each repair that affects 
any fatigue critical alteration structure identified under paragraph 
(b)(2) of this section;
    (2) For each repair identified under paragraph (d)(1) of this 
section, unless previously accomplished, perform a DTE and develop DTI;
    (3) Submit the DT data developed in accordance with paragraph 
(d)(2) of this section to the FAA Oversight Office or its properly 
authorized designees for review and approval; and
    (4) Upon approval, make the DTI available to persons required to 
comply with Sec. Sec.  121.1109 and 129.109 of this chapter.
    (e) Compliance times. Holders of supplemental type certificates 
must submit the following to the FAA

[[Page 70508]]

Oversight Office or its properly authorized designees for review and 
approval by the specified compliance time:
    (1) The list of fatigue critical alteration structure required by 
paragraph (b)(3) of this section must be submitted no later than 360 
days after January 11, 2008.
    (2) For alteration data developed and approved before January 11, 
2008, the DT data required by paragraph (c)(2) of this section must be 
submitted by June 30, 2009.
    (3) For alteration data developed after January 11, 2008, the DT 
data required by paragraph (c)(2) of this section must be submitted 
before approval of the alteration data and making it available to 
persons required to comply with Sec. Sec.  121.1109 and 129.109 of this 
chapter.
    (4) For repair data developed and approved before January 11, 2008, 
the DT data required by paragraph (d)(2) of this section must be 
submitted by June 30, 2009.
    (5) For repair data developed and approved after January 11, 2008, 
the DT data required by paragraph (d)(2) of this section, must be 
submitted within 12 months after initial approval of the repair data 
and before making the DT data available to persons required to comply 
with Sec. Sec.  121.1109 and 129.109 of this chapter.

Sec.  26.49  Compliance plan.

    (a) Compliance plan. Except for applicants for type certificates 
and supplemental type certificates whose applications are submitted 
after January 11, 2008, each person identified in Sec. Sec.  26.43, 
26.45, and 26.47, must submit a compliance plan consisting of the 
following:
    (1) A project schedule identifying all major milestones for meeting 
the compliance times specified in Sec. Sec.  26.43(f), 26.45(e), and 
26.47(e), as applicable.
    (2) A proposed means of compliance with Sec. Sec.  26.43, 26.45, 
and 26.47, as applicable.
    (3) A plan for submitting a draft of all compliance items required 
by this subpart for review by the FAA Oversight Office not less than 60 
days before the applicable compliance date.
    (b) Compliance dates for compliance plans. The following persons 
must submit the compliance plan described in paragraph (a) of this 
section to the FAA Oversight Office for approval on the following 
schedule:
    (1) For holders of type certificates, no later than 90 days after 
January 11, 2008.
    (2) For holders of supplemental type certificates no later than 180 
days after January 11, 2008.
    (3) For applicants for changes to type certificates whose 
application are submitted before January 11, 2008, no later than 180 
days after January 11, 2008.
    (c) Compliance Plan Implementation. Each affected person must 
implement the compliance plan as approved in compliance with paragraph 
(a) of this section.

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

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

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

0
5. Amend Sec.  121.1109 to revise paragraph (c) to read as follows:

Sec.  121.1109  Supplemental inspections.

* * * * *
    (c) General requirements. After December 20, 2010, a certificate 
holder may not operate an airplane under this part unless the following 
requirements have been met:
    (1) Baseline Structure. The certificate holder's maintenance 
program for the airplane includes FAA-approved damage-tolerance-based 
inspections and procedures for airplane structure susceptible to 
fatigue cracking that could contribute to a catastrophic failure. For 
the purpose of this section, this structure is termed ``fatigue 
critical structure.''
    (2) Adverse effects of repairs, alterations, and modifications. The 
maintenance program for the airplane includes a means for addressing 
the adverse effects repairs, alterations, and modifications may have on 
fatigue critical structure and on inspections required by paragraph 
(c)(1) of this section. The means for addressing these adverse effects 
must be approved by the FAA Oversight Office.
    (3) Changes to maintenance program. The changes made to the 
maintenance program required by paragraphs (c)(1) and (c)(2) of this 
section, and any later revisions to these changes, must be submitted to 
the Principal Maintenance Inspector for review and approval.

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

0
6. The authority citation for part 129 continues to read as follows:

    Authority: 49 U.S.C. 1372, 49113, 440119, 44101, 44701-44702, 
447-5, 44709-44711, 44713, 44716-44717, 44722, 44901-44904, 44906, 
44912, 44105., Pub. L. 107-71 sec. 104.

0
7. Amend 129.109 by revising paragraph (b) to read as follows:

Sec.  129.109  Supplemental inspections for U.S.-registered aircraft.

* * * * *
    (b) General requirements. After December 20, 2010, a certificate 
holder may not operate an airplane under this part unless the following 
requirements have been met:
    (1) Baseline Structure. The certificate holder's maintenance 
program for the airplane includes FAA-approved damage-tolerance-based 
inspections and procedures for airplane structure susceptible to 
fatigue cracking that could contribute to a catastrophic failure. For 
the purpose of this section, this structure is termed ``fatigue 
critical structure.''
    (2) Adverse effects of repairs, alterations, and modifications. The 
maintenance program for the airplane includes a means for addressing 
the adverse effects repairs, alterations, and modifications may have on 
fatigue critical structure and on inspections required by paragraph 
(b)(1) of this section. The means for addressing these adverse effects 
must be approved by the FAA Oversight Office.
    (3) Changes to maintenance program. The changes made to the 
maintenance program required by paragraph (b)(1) and (b)(2) of this 
section, and any later revisions to these changes, must be submitted to 
the Principal Maintenance Inspector for review and approval.

Robert A. Sturgell,
Acting Administrator.
[FR Doc. 07-6016 Filed 12-7-07; 12:04 pm]

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