70486 Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 

the FDA review and approval of a New 

Animal Drug Application or New Drug 

Application. 

(g)–(z) [Reserved] 

Dated: December 5, 2007. 

Lloyd C. Day, 

Administrator, Agricultural Marketing 

Service. 

[FR Doc. E7–23915 Filed 12–11–07; 8:45 am] 

BILLING CODE 3410–02–P 

FEDERAL RESERVE SYSTEM 

12 CFR Part 220 

[Regulation T; Docket No. R–1301] 

Credit by Brokers and Dealers 

AGENCY: Board of Governors of the 

Federal Reserve System. 

ACTION: Final rule; correcting 

amendment. 

SUMMARY: The Board of Governors of the 

Federal Reserve System (Board) is 

amending Regulation T (Credit by 

Brokers and Dealers) to correct a crossreference in one of its interpretations. 

DATES: Effective Date: December 12, 

2007. 

FOR FURTHER INFORMATION CONTACT: 

Scott Holz, Senior Counsel, Legal 

Division (202–452–2966). For users of 

the Telecommunications Device (TDD) 

only, please call 202–263–4869. 

SUPPLEMENTARY INFORMATION: The 

National Securities Markets 

Improvement Act of 1996 (NSMIA). 

(Pub. L. 104–290, 110 Stat. 3416) 

amended section 7 of the Securities 

Exchange of 1934 (15 U.S.C. 78g) to 

limit the Board’s authority to impose 

restrictions on credit extended, 

maintained, or arranged to or for a 

member of a national securities 

exchange or a registered broker or 

dealer, a substantial portion of whose 

business consists of transactions with 

persons other than brokers or dealers, or 

to finance its activities as a market 

maker or an underwriter. Restrictions on 

these types of credit were found at that 

time in Regulations G, T and U (12 CFR 

Parts 207, 220, and 221, respectively). 

NSMIA gave the Board the authority 

to maintain or adopt restrictions on 

these types of credit if it determines that 

such action is necessary or appropriate 

in the public interest or for the 

protection of investors. In November 

1996, the Board adopted an 

interpretation of its margin regulations 

(1996 interpretation), indicating that the 

Board had not made such a finding (61 

FR 60166, November 26, 1996). The 

1996 interpretation stated the Board’s 

belief that the restrictions on these types 

of credit found in the Regulations G, T 

and U had been superseded by NSMIA. 

NSMIA also repealed section 8(a) of 

the Securities Exchange Act of 1934, 

dealing with extensions of credit to 

brokers and dealers collateralized with 

exchange-traded securities. The Board’s 

1996 interpretation indicated that the 

provisions in Regulations G, T and U 

adopted to implement section 8(a) of the 

Securities Exchange Act of 1934 were 

without effect in light of NSMIA. 

The text of the 1996 interpretation 

was published as part of Regulation G, 

and Regulations T and U were amended 

with interpretations that referred to the 

text of the 1996 interpretation appearing 

in Regulation G. 

In 1998, the Board adopted regulatory 

amendments to remove the restrictions 

that conflicted with NSMIA (63 FR 

2806, January 16, 1998). As part of this 

process, the Board amended the 1996 

interpretation to delete references to the 

conflict between the regulations and 

NSMIA. The remaining provisions of 

Regulation G, including the amended 

1996 interpretation, were incorporated 

into Regulation U. However, the 

reference in Regulation T to the text of 

the 1996 interpretation was 

inadvertently not changed to reflect the 

elimination of Regulation G. Today’s 

action will correct this cross-reference 

by amending Regulation T to reflect the 

fact that the text of the amended 1996 

interpretation now appears in 

Regulation U. 

List of Subjects in 12 CFR Part 220 

Banks, banking, Brokers, Credit, 

Federal Reserve System, Margin, Margin 

requirements, Reporting and 

recordkeeping requirements, Securities. 

■ For the reasons set forth in the 

preamble, part 220 is amended to read 

as follows: 

PART 220—CREDIT BY BROKERS 

AND DEALERS (REGULATION T) 

■ 1. The authority citation for part 220 

continues to read as follows: 

Authority: 15 U.S.C. 78c, 78g, 78q, and 

78w. 

§ 220.132 [Amended] 

■ 2. In § 220.132, introductory 

paragraph, replace the phrase 

‘‘§ 207.114’’ with ‘‘§ 221.125.’’

By order of the Secretary of the Board, 

acting pursuant to delegated authority for the 

Board of Governors of the Federal Reserve 

System, December 7, 2007. 

Jennifer J. Johnson, 

Secretary of the Board. 

[FR Doc. E7–24052 Filed 12–11–07; 8:45 am] 

BILLING CODE 6210–01–P 

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. 

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 


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Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 70487 

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. 

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. 

3 70 FR 5518; February 2, 2005. 

4The 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. 

5For 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. 

6Published 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. 

7This 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. 

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. 

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. 

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.’’

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. 

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

• TC holder’s future repair data not 

published for general use.7

• 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 


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70488 Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 

8 71 FR 20574. 

9AASFR: 70 FR 5518; February 2, 2005. See also 

70 FR 23935; May 6, 2005: Aging Airplane Safety; 

Correcting Amendment. 

10 69 FR 45936; July 30, 2004. 

11 67 FR 72726; December 6, 2002. 

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). 

14 71 FR 20750. 

15 Issued as AC 120–93. 

16AAWG 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). 

17 71 FR 38541. 

18 72 FR 8834. 

19 Issued as AC 120–93. 

20 72 FR 63364; November 8, 2007. 

21Certification Procedures for Products and Parts. 

22This section, which includes an applicability 

table for part 26, was adopted as part of the EAPAS 

final rule. 

23These definitions were proposed in 

§ 25.1823(b). 

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. 

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. 

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. 

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. 

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. 

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. 

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. 

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. 

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. 

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 Tolerance 

Data for Repairs 

and Alterations.

Subpart I—Continued 

Airworthiness. 

§ 26.5 Applicability 

table.

New.22

§ 26.41 Definitions ..... New.23

§ 26.43 Holders of 

and applicants for 

type certificates— 

Repairs.

§ 25.1823 Holders of 

type certificates— 

Repairs. 

§ 26.45 Holders of 

type certificates— 

Alterations and repairs to alterations.

§ 25.1825 Holders of 

type certificates— 

Alterations and repairs to alterations. 

§ 26.47 Holders of 

and applicants for a 

supplemental type 

certificate—Alterations and repairs 

to alterations.

§ 25.1827 Holders of 

and applicants for a 

supplemental type 

certificate—Alterations and repairs 

to alterations. 


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Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 70489 

24The 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. 

25 Issued as AC 120–93. 

TABLE 1.—RELATIONSHIP OF PROPOSED PART 25 SUBPART I TO PART

26 FINAL RULES—Continued 

Part 26 final rules Proposed part 25 

§ 26.49 Compliance 

Plan.

§ 25.1829 Compliance Plan. 

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 DTrelated requirements. 

Prior sections Redesignated sections 

§ 121.370a ................. § 121.1109 

§ 129.16 ..................... § 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 

§§ 121.370a and 129.16 (redesignated as 

§§ 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. 

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 §§ 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 §§ 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 

§§ 121.1109 and 129.109 to include 

requirements related to baseline 

structure in § 121.1109(c)(1) and 

§ 129.109(b)(1) and those related to 

repairs, alterations, and modifications in 

§ 121.1109(c)(2) and § 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. 

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 

§ 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 § 25.1823(f)(3) 

(adopted as § 26.43(e)(3)) to remove the 

reference to § 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 

§ 25.1829 (adopted as § 26.49). 

Specifically, we removed the proposed 

requirements in § 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 § 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 


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70490 Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 

26AAWG 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. 

27 71 FR 19928; April 18, 2006. 

28 43 FR 46242; October 5, 1978. 

29The 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. 

believe removal of these requirements 

will adversely affect our ability to 

facilitate DAH compliance. 

In § 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 § 25.1823 (the 

definitions are now in § 26.41). We also 

made other minor changes to clarify the 

requirements in proposed §§ 25.1823 

(adopted as § 26.43), 25.1825 (adopted 

as § 26.45), 25.1827 (adopted as § 26.47), 

and 25.1829 (adopted as § 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. 

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. 

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. 

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. 

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 


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(ARAC), supports operator compliance 

with the AASFR with respect to repairs 

and alterations. 

As amended by this final rule, 

§ 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 §§ 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 § 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 DTjustified modifications and repairs. 

Airbus asked the FAA to reconsider 

applying proposed §§ 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 

§ 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 § 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 § 26.49 (proposed as 

§ 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 § 25.571 (Amendment 45 or later). 

It said it presumes these airplanes will 

continue to be regulated under 

§ 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 § 25.1823 (lists of 

fatigue critical baseline structure, 

damage tolerance inspections, damage 

tolerance evaluation guidelines, and 

implementation schedules) are already 

required under § 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 

§ 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 §§ 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 passengercarrying 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’


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30 71 FR 20583. 

31 § 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) 

* * *.’’

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 § 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 

§ 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 § 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 § 25.571 in the sentence 

noted below, we intended to rely on the 

many precedents established in finding 

compliance with this section. 

Because of industry’s extensive experience 

in showing compliance with the damage 

tolerance requirements of § 25.571, these key 

terms [e.g., fatigue critical structure] should 

be readily understood and applied. 

To clarify how the criteria of § 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 § 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 § 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 § 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. 

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 § 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 § 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 


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32 71 FR at 20583. 

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 § 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 

§ 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. 

Regarding the concern that STC 

holders may not have experience in 

complying with § 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 § 25.1309, our 

intent is to use the same method to 

identify FCS that is required by 

§ 25.571. Paragraph (a) of § 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 § 25.571. TC holders are required 

under § 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, §§ 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 §§ 25.1825(c) 

and 25.1827(c) (adopted as 

§§ 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 §§ 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 §§ 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 


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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 

§§ 25.1825(c) and 25.1827(c) (adopted as 

§§ 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 

§§ 25.1825(c) and 25.1827(c) (adopted as 

§§ 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 § 26.45(c)(1)) 

and 25.1827(c)(1) (adopted as 

§ 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 reevaluation 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 § 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 § 25.571 

(Amendment 25–45) and later. 


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33Repair Assessment for Pressurized Fuselages 

final rule (65 FR 24108; April 25, 2000). 34 Issued as AC 120–93. 

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 § 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 § 121.370 

(redesignated as § 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. 

G. Repair Evaluation Guidelines (REGs) 

This final rule requires TC holders to 

develop REGs that include processes 

operators could use to support 

compliance with §§ 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 § 25.1823(f)(1)(iii) and (f)(4) 

(adopted as § 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 

§ 25.1823(f)(1)(iii) (adopted as 

§ 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 § 25.1823(f)(3) (adopted as 

§ 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 § 25.1823(f)(4) 

(adopted as § 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 § 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 § 25.1827 should 

be removed from § 25.1823. Section 

25.1827 is applicable to holders of and 

applicants for an STC. In reading 

§ 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 § 25.1823. 

According to § 25.1827 and AC 120–XX, 

the only data required by an STC holder 

is the list of fatigue critical structure, as 

stipulated in § 25.1823(c)(2). In light of 

this, Boeing said, the reference to 

§ 25.1827 should be deleted from 

proposed § 25.1823. 

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 

§ 25.1823(f)(4) appears to be using 

incorrect terminology. It said the 

wording in § 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 


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35 Issued as AC 120–93. 

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 § 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, (§§ 25.1825 and 

25.1827 (adopted as §§ 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 § 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 

§ 25.1825(c) and § 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 

§§ 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 

§§ 25.1825(c) and 25.1827(c) (adopted as 

§§ 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. 

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) 


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36 14 CFR 21.3 and 121.703. 

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 §§ 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 § 25.1829 

(adopted as § 26.49) without adversely 

affecting our ability to facilitate DAH 

compliance. Specifically, in 

§ 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, § 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 noncompliance, 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 §§ 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 § 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. 

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 


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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 §§ 25.1823(d) 

and 25.1825(c) and (d) for alteration and 


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37Special maintenance program requirements. 

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 

§ 121.37037 (redesignated as 

§ 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. 

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 

§ 25.571 for repairs and alterations. The 

FAA does not agree with the 


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38 69 FR 26641; May 13, 2004. 

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 § 121.370 

(redesignated as § 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 DTbased 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 

§ 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 

§ 25.1825(e)(1), they would have 90 

days to submit their lists of fatigue 

critical alteration structure. In proposed 

§ 25.1827(e)(1), STC holders would have 

270 days to submit their lists of fatigue 

critical alteration structure. 

In the final rule (§ 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 (§§ 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 FAAapproved 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: 

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 §§ 121.370a 

and 129.16 [redesignated as §§ 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 


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39 67 FR 72726; December 6, 2002. 

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. 

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 § 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 


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40 70 FR 5518, February 2, 2005. 

41Fuselage, door skins, and bulkhead webs. 

42A–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. 

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 

AASFR40 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. 

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 §§ 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 § 25.571 to perform a damage 

tolerance evaluation and establish, as 

necessary, damage tolerance inspections 

or other procedures. On preAmendment 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 § 121.370 

(redesignated as § 121.1107). By 

December 2010, damage tolerance 

inspections for the baseline structure 

and repairs and alterations will be 

required by §§ 121.1109 and 129.109 for 

airplanes certificated after January 1, 

1958 that have a passenger seating 


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43Supplemental Inspection Document. 

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. 

The following table summarizes the 

regulatory requirements for DT 

inspection programs. The shaded areas 

in the table represent regulatory gaps 

filled by the AASFR (§ 121.1109) 

requirements to develop DT inspections 

and procedures for fatigue critical 

airplane structural areas. 

BILLING CODE 4910–13–P 

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 


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44 70 FR 5518, February 2, 2005. 

45The 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. 

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. 

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-forprofit 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. 

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 smallentity 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 


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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 

■ 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 

■ 1. The authority citation for part 26 

continues to read as follows: 

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

44702 and 44704. 

■ 2. Revise § 26.5 to read as follows: 

§ 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 

Future2 STC/ATC Applicants ........................................................................................................... 26.11 ......................... 26.45, 26.47, 26.49 

Manufacturers .................................................................................................................................. N/A ............................ N/A 

Persons seeking design approval of repairs ................................................................................... N/A ............................ N/A 

1As of the effective date of the identified rule. 

2Application made after the effective date of the identified rule. 

■ 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. 

§ 26.41 Definitions. 

§ 26.43 Holders of and applicants for type 

certificates—Repairs. 

§ 26.45 Holders of type certificates—

Alterations and repairs to alterations. 

§ 26.47 Holders of and applicants for a 

supplemental type certificate—

Alterations and repairs to alterations. 

§ 26.49 Compliance plan. 

Subpart C—[Reserved] 

Subpart D—[Reserved] 

Subpart E—Aging Airplane Safety—

Damage Tolerance Data for Repairs 

and Alterations 

§ 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 


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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 § 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). 

§ 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 § 26.47 and §§ 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 §§ 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 §§ 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 § 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 §§ 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. 


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(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. 

§ 26.45 Holders of type certificates—

Alterations and repairs to alterations. 

(a) Applicability. This section applies 

to transport category airplanes subject to 

§ 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 § 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 §§ 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 § 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 §§ 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 §§ 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 §§ 121.1109 and 129.109 of 

this chapter. 

§ 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 

§ 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 § 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 §§ 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 § 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 §§ 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 §§ 121.1109 and 129.109 of this 

chapter. 

(e) Compliance times. Holders of 

supplemental type certificates must 

submit the following to the FAA 


yshivers on PROD1PC62 with RULES
70508 Federal Register / Vol. 72, No. 238 / Wednesday, December 12, 2007 / Rules and Regulations 

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 

§§ 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 §§ 121.1109 and 129.109 of 

this chapter. 

§ 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 

§§ 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 

§§ 26.43(f), 26.45(e), and 26.47(e), as 

applicable. 

(2) A proposed means of compliance 

with §§ 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 

■ 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. 

■ 5. Amend § 121.1109 to revise 

paragraph (c) to read as follows: 

§ 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 

■ 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. 

■ 7. Amend 129.109 by revising 

paragraph (b) to read as follows: 

§ 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] 

BILLING CODE 4910–13–P 


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