69746 Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Parts 25, 26, 121, and 129 

[Docket No. FAA–2006–24281; Amendment 

Nos. 25–132, 26–5, 121–351, 129–48] 

RIN 2120–AI05 

Aging Airplane Program: Widespread 

Fatigue Damage 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: This final rule amends FAA 

regulations pertaining to certification 

and operation of transport category 

airplanes to prevent widespread fatigue 

damage in those airplanes. For certain 

existing airplanes, the rule requires 

design approval holders to evaluate 

their airplanes to establish a limit of 

validity of the engineering data that 

supports the structural maintenance 

program (LOV). For future airplanes, the 

rule requires all applicants for type 

certificates, after the affective date of the 

rule, to establish an LOV. Design 

approval holders and applicants must 

demonstrate that the airplane will be 

free from widespread fatigue damage up 

to the LOV. The rule requires that 

operators of any affected airplane 

incorporate the LOV into the 

maintenance program for that airplane. 

Operators may not fly an airplane 

beyond its LOV unless an extended LOV 

is approved. 

DATES: These amendments become 

effective January 14, 2011. 

FOR FURTHER INFORMATION CONTACT: If 

you have technical questions 

concerning this rule, contact Walter 

Sippel, ANM–115, Airframe/Cabin 

Safety Branch, Federal Aviation 

Administration, 1601 Lind Avenue SW., 

Renton, WA 98057–3356; telephone 

(425) 227–2774; facsimile (425) 227– 

1232; e-mail walter.sippel@faa.gov. If 

you have legal questions, contact Doug 

Anderson, Office of Regional Counsel, 

Federal Aviation Administration, 1601 

Lind Avenue SW., Renton, WA 98057– 

3356; telephone (425) 227–2166; 

facsimile (425) 227–1007; e-mail 

douglas.anderson@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Authority for This Rulemaking 

The FAA’s authority to issue rules on 

aviation safety is found in Title 49 of the 

United States Code. Subtitle I, section 

106 describes the authority of the FAA 

Administrator. Subtitle VII–Aviation 

Programs describes in more detail the 

scope of the agency’s authority. 

This rulemaking is promulgated 

under the authority described in subtitle 

VII, part A, subpart III, section 44701, 

‘‘General requirements.’’ Under that 

section, the FAA is charged with 

promoting safe flight of civil aircraft in 

air commerce by prescribing minimum 

standards required in the interest of 

safety for the design and performance of 

aircraft; regulations and minimum 

standards in the interest of safety for 

inspecting, servicing, and overhauling 

aircraft; and regulations for other 

practices, methods, and procedures the 

administrator finds necessary for safety 

in air commerce. This regulation is 

within the scope of that authority 

because it prescribes— 

• New safety standards for the design 

of transport category airplanes, and 

• New requirements necessary for 

safety for the design, production, 

operation and maintenance of those 

airplanes and for other practices, 

methods, and procedures relating to 

those airplanes. 

Contents 

I. Executive Summary 

II. Background 

A. Summary of the NPRM 

B. Related Activities 

C. Differences between NPRM and Final 

Rule 

1. Substantive changes 

2. Regulatory Evaluation changes 

3. New part 26 for design approval holders’ 

airworthiness requirements 

4. New subparts for airworthiness 

operational rules 

D. Summary of Comments 

III. Discussion of the Final Rule 

A. Overview 

1. Widespread fatigue damage 

2. Final rule 

B. Requests for Deferral or Withdrawal of 

Rule 

1. Safety benefits don’t justify rule 

2. Existing programs serve purpose of rule 

3. Divide rule into two 

C. Concept of Operational Limits 

1. Requests for requiring maintenance 

programs instead 

2. Single retirement point for a model 

3. Potentially adverse effect on safety 

D. Change in Terminology (Initial 

Operational Limit to LOV) 

1. Rationale for the term LOV 

2. Refer to the structural maintenance 

program 

E. Repairs, Alterations, and Modifications 

1. Whether repairs, alterations, and 

modifications pose WFD risks 

2. Relationship to damage tolerance 

requirements (§ 25.571) 

a. Pre-Amendment 25–96 airplanes 

b. Airplanes certified to Amendment 25–96 

or later 

3. Guidelines for repairs, alterations, and 

modifications 

4. Rely on the Changed Product Rule 

F. LOVs for Existing Airplanes 

1. NPRM compliance date 

2. When to set LOVs for existing airplanes 

a. Pre-Amendment 25–45 airplanes 

b. Airplanes certified to Amendment 25–45 

or later 

3. Varying implementation strategies 

4. FAA review and approval time 

G. LOVs for Future Airplanes: Revisions to 

§ 25.571 and Appendix H 

1. Opposition to changes to § 25.571 

2. Change to Appendix H 

3. When to set LOVs for future airplanes 

H. How to Set LOVs 

I. How to Extend LOVs 

1. Change the procedure for extending 

LOVs 

2. Evaluation of repairs, alterations, and 

modifications for LOV extensions 

3. Alternate means of compliance (AMOCs) 

4. Extension procedure doesn’t allow 

public comment 

J. Applicability for Existing Airplanes 

1. Type certificates issued after January 1, 

1958 

2. Original type certification 

3. Airplane configuration 

4. Weight cutoff 

5. Default LOVs and excluded airplanes 

a. Table 1—Default LOVs 

b. Table 2—Airplanes excluded from 

§ 26.21 

6. Bombardier airplanes 

7. Intrastate operations in Alaska 

8. Composite structures 

K. Harmonization 

L. Regulatory Evaluation 

1. Benefits of proposed rule 

2. Costs of proposed rule 

a. Need to know LOVs to determine cost 

b. Need to know maintenance actions to 

determine cost 

c. Costs to manufacturers 

d. Cost of failing to harmonize rule 

e. Cost to replace an airplane 

f. Residual value of airplanes 

3. ‘‘Rotable’’ parts 

4. Use of LOVs for financial evaluations 

IV. Regulatory Notices and Analyses 

I. Executive Summary 

This final rule requires certain actions 

to prevent catastrophic failure due to 

widespread fatigue damage (WFD) 

throughout the operational life of 

certain existing transport category 

airplanes and all those to be certificated 

in the future. Existing airplanes subject 

to the rule are turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, which have a 

maximum takeoff gross weight greater 

than 75,000 pounds and are operated 

under part 121 or 129. The rule applies 

to all transport category airplanes to be 

certificated in the future, regardless of 

maximum takeoff gross weight or how 

they are operated. The benefits of this 

rule are estimated at a present value of 

$4.8 million. The cost is estimated at a 

present value of $3.6 million. 


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Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 69747 

1After sustaining a certain level of damage, the 

remaining structure must be able to withstand 

certain static loads without failure. In the context 

of WFD, the damage is a result of the simultaneous 

presence of fatigue cracks at multiple locations in 

the same structural element (i.e., multiple site 

damage) or the simultaneous presence of fatigue 

cracks in similar adjacent structural elements (i.e., 

multiple element damage). 

2Baseline structure means structure that is 

designed under the original type certificate or 

amended type certificate for that airplane model. 3 71 FR 19928 

FIGURE 1—WFD FINAL RULE

BENEFITS AND COSTS

Nominal value 

($ millions) 

7% Present 

value 

($ millions) 

Benefits ..... 9.8 4.8 

Costs ......... 3.8 3.6 

Fatigue damage to a metallic structure 

occurs when the structure is subjected 

to repeated loads, such as the 

pressurization and depressurization that 

occurs with every flight of an airplane. 

Over time this fatigue damage results in 

cracks in the structure, and the cracks 

may begin to grow together. Widespread 

fatigue damage is the simultaneous 

presence of fatigue cracks at multiple 

structural locations that are of sufficient 

size and density that the structure will 

no longer meet the residual strength 

requirements of § 25.571(b).1 Structural 

fatigue characteristics of airplanes are 

understood only up to the point where 

analyses and testing of the structure are 

valid. There is concern about operating 

an airplane beyond that point for several 

reasons. One reason is that WFD is 

increasingly likely as the airplane ages, 

and is certain if the airplane is operated 

long enough. Another is that existing 

inspection methods do not reliably 

detect WFD because cracks are initially 

so small and may then link up and grow 

so rapidly that the affected structure 

fails before an inspection can be 

performed to detect the cracks. 

To preclude WFD related incidents in 

existing transport category airplanes, 

this final rule requires holders of design 

approvals for those airplanes subject to 

the rule to perform the following 

actions: 

1. Establish a limit of validity of the 

engineering data that supports the 

structural maintenance program (LOV); 

2. Demonstrate that WFD will not 

occur in the airplane prior to reaching 

the LOV; and 

3. Establish or revise the 

Airworthiness Limitations section in the 

Instructions for Continued 

Airworthiness to include the LOV. 

As used in this preamble, the term 

‘‘design approval holders’’ includes 

holders of type certificates, 

supplemental type certificates, or 

amended type certificates, and 

applicants for such approvals. In the 

context of this final rule, the design 

approval holder is generally the type 

certificate holder. Requiring design 

approval holders to perform the actions 

listed above is intended to support 

compliance by operators with today’s 

amendments to parts 121 and 129. This 

final rule amends those parts to require 

that operators incorporate the LOV as 

airworthiness limitations into their 

maintenance program for each affected 

model that they operate. 

The amendments to the operating 

rules have the effect of prohibiting 

operation of an airplane beyond its 

LOV. However, today’s rule provides an 

option for any person to extend the LOV 

for an airplane and to develop the 

maintenance actions which support the 

extended limit. Thereafter, to operate an 

airplane beyond the existing LOV, an 

operator must incorporate the extended 

LOV and associated maintenance 

actions into its maintenance program. 

The airplane may not be operated 

beyond the extended LOV. 

In response to comments on the 

notice of proposed rulemaking, the FAA 

has made a number of substantive 

changes which significantly reduce the 

costs presented in the proposal. The 

FAA has— 

• Eliminated the requirement to 

evaluate WFD associated with most 

repairs, alterations, and modifications of 

the baseline 2 airplane structure. 

• Simplified how an LOV may be 

extended. 

• Extended the compliance dates by 

which design approval holders must 

establish an LOV for existing airplanes. 

• Extended the time for operators to 

incorporate LOVs into their 

maintenance programs. 

• Limited the applicability of the 

final rule to ‘‘transport category, turbinepowered airplanes with a type 

certificate issued after January 1, 1958.’’ 

Today’s rule requires that design 

approval holders take the necessary 

steps to preclude WFD in the future by 

requiring that they establish LOVs. 

Although the rule allows design 

approval holders to establish LOVs 

without relying on maintenance actions, 

the FAA expects most current design 

approval holders to adopt LOVs that 

will rely on such actions. Since WFD is 

by definition a condition in which 

structure will no longer meet the 

residual strength requirements of 

§ 25.571(b), it could lead to a 

catastrophic failure. Thus the FAA 

would mandate those maintenance 

actions by airworthiness directive. The 

agency expects these actions to greatly 

reduce the number of unanticipated 

inspections and repairs resulting from 

emergency airworthiness directives the 

FAA issues when WFD is discovered in 

service. The FAA estimates the value of 

managing WFD with maintenance 

actions developed under this final rule 

versus the current practice of issuing 

airworthiness directives as WFD is 

found is worth $4.8 million in present 

value. There are other benefits of this 

rule that were not included in the final 

benefit assessment. They include 

prevention of accidents and a longer 

economic life for the airplane. The FAA 

estimates that this rule will cause one 

airplane to be retired because of its 

reaching the anticipated LOV in the 20- 

year analysis period. The retirement of 

this one airplane will result in costs of 

approximately $3.8 million, with a 

present value of approximately $3.6 

million. This operator’s cost is the only 

cost attributed to the final rule, since 

manufacturer costs were found to be 

minimal. 

Thus, as noted earlier, this final rule’s 

estimated present value benefits of $4.8 

million exceed the estimated present 

value costs of approximately $3.6 

million. 

II. Background 

A. Summary of the NPRM 

On April 18, 2006, the FAA published 

a notice of proposed rulemaking 

(NPRM), entitled Aging Aircraft 

Program: Widespread Fatigue Damage.3

That proposal was based on a 

recommendation from the Aviation 

Rulemaking Advisory Committee 

(ARAC). The NPRM contained extensive 

requirements for setting and supporting 

an initial operational limit for an 

airplane model. The FAA proposed that 

the rule apply to transport category 

airplanes with a maximum gross takeoff 

weight of greater than 75,000 pounds. 

The due date for comments was July 17, 

2006. 

The FAA proposed that design 

approval holders for those airplanes be 

required to take actions to preclude 

WFD. For new airplanes, the FAA 

proposed to amend § 25.571 and 

Appendix H to part 25 to require that 

applicants for a new type certificate 

establish an initial operational limit and 

include that limit in the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness for the 

airplane. The agency also proposed that 

applicants develop guidelines for 

evaluating repairs, alterations, and 

modifications for WFD. 


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69748 Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 

4 69 FR 45936, July 30, 2004. 

5 70 FR 40168, July 12, 2005: Fuel Tank Safety 

Compliance Extension (final rule) and Aging 

Airplane Program Update (Request for comments). 

6 70 FR 40166, July 12, 2005 (PS–ANM110–7–12– 

2005). 

7 71 FR 38540. 

8The final rule requires that design approval 

holders evaluate airplane configurations that 

include modifications mandated by airworthiness 

directive. 

Section 25.1807 proposed that holders 

of design approvals for existing 

airplanes or applicants for such 

approvals be required to do the 

following: 

1. Establish an initial operational 

limit; and 

2. Establish a new Airworthiness 

Limitations section or revise an existing 

Airworthiness Limitations section to 

include the initial operational limit. 

Section 25.1807(g) proposed that 

holders of design approvals for existing 

airplanes or applicants for such 

approvals be required to prepare the 

following: 

1. A list of repairs and modifications 

developed and documented by the 

design approval holder; 

2. Service information for 

maintenance actions necessary to 

preclude WFD from occurring before the 

initial operational limit; and 

3. Guidelines for identifying, 

evaluating, and preparing service 

information for repairs, alterations, and 

modifications for which no service 

information exists. 

For existing airplanes for which an 

initial operational limit is established, 

§ 25.1809 proposed that design changes 

be evaluated for susceptibility to WFD 

and, if a change were susceptible, that 

the design approval holder identify 

when WFD is likely to occur and 

whether maintenance actions would be 

required. Section 25.1811 provided that 

any person could apply to extend an 

operational limit, using a process 

similar to that for establishing the initial 

operational limit. Under § 25.1813, 

certain repairs, alterations, and 

modifications proposed for installation 

on airplanes with an extended 

operational limit would also be 

evaluated. 

The FAA proposed to amend the 

operating requirements of parts 121 and 

129 to require that no operator could 

operate an airplane unless the initial 

operational limit or extended 

operational limit for the airplane had 

been incorporated into the operator’s 

maintenance program. 

The NPRM contains the background 

and rationale for this rulemaking and, 

except where the FAA has made 

revisions in this final rule, should be 

referred to for that information. 

B. Related Activities 

In July 2004, the FAA published the 

notice entitled ‘‘Fuel Tank Safety 

Compliance Extension (Final Rule) and 

Aging Airplane Program Update 

(Request for Comments)’’ 4 to propose 

airworthiness requirements for design 

approval holders to support certain 

operational rules. The FAA requested 

comments on the agency’s proposal. 

In July 2005, the FAA published a 

disposition of comments received in 

response to our request.5 Also in July 

2005, the agency published a policy 

statement, ‘‘Safety–A Shared 

Responsibility–New Direction for 

Addressing Airworthiness Issues for 

Transport Airplanes,’’ 6 that explains our 

reasons for adopting requirements for 

design approval holders. 

On May 22, 2006, the FAA published 

a Notice of Availability and request for 

comments on proposed Advisory 

Circular (AC) 120–YY, Widespread 

Fatigue Damage on Metallic Structure. 

The notice stated that the proposed AC 

could be found on the Internet at 

http://www.faa.gov/aircraft/draft_docs. 

This proposed advisory circular 

provides guidance to design approval 

holders on establishing initial and 

extended operational limits to preclude 

WFD for certain transport category 

airplanes and evaluating repairs, 

alterations, and modifications to the 

airplanes. The advisory circular also 

provides guidance to operators on 

incorporating the initial or extended 

operational limit and any related 

airworthiness limitation items into their 

maintenance programs. The notice 

specified that comments on the 

proposed advisory circular were to be 

received by July 17, 2006. 

On July 7, 2006, at the request of a 

number of commenters, the FAA 

published a notice 7 extending the 

comment period on both the NPRM and 

proposed AC 120–YY to September 18, 

2006. On August 18, 2006, the agency 

posted proposed AC 25.571–1X, Damage 

Tolerance and Fatigue Evaluation of 

Structure, on the Internet at http:// 

www.faa.gov/aircraft/draft_docs. 

Comments on this document, which 

proposed revision of existing AC 

25.571–1C, were due by October 21, 

2006. 

On November 26, 2006, the FAA held 

a public meeting with the ARAC 

Transport Airplane and Engine Issues 

Group. Under ARAC, the Airworthiness 

Assurance Working Group (AAWG) had 

previously provided recommendations 

to the FAA on how to address 

widespread fatigue damage. Because the 

FAA had received several comments 

concerning differences between the 

AAWG’s recommendations and the 

NPRM, the meeting was held to discuss 

the reasons for these differences. The 

FAA’s presentation at the meeting has 

been placed in the docket for this 

rulemaking. Except as discussed in the 

context of specific issues affecting this 

final rule, the FAA will not revisit those 

differences here. 

On December 11, 2008, at the request 

of the Acting Administrator, the FAA 

held a public meeting to allow 

comments on the changes that had 

occurred to the rule since it had been 

proposed in the NPRM. A Technical 

Document describing those changes was 

posted in the docket, and the 

announcement of the meeting and 

opening of the comment period for the 

Technical Document was published in 

the Federal Register on Nov. 7, 2008 (73 

FR 66205). The public was invited to 

submit comments on the Technical 

Document either in person at the 

meeting or by sending them to the 

docket. Seventy-one people attended the 

meeting and Boeing, the Air Transport 

Association of America (ATA), and 

FedEx made presentations, along with 

the FAA. Many attendees commented or 

asked questions. In addition, 12 

commenters submitted comments about 

the Technical Document to the docket. 

The comment period closed on 

December 22, 2008. 

While some of the comments received 

during the comment period for the 

Technical Document were new, many 

were restatements of comments made 

after publication of the NPRM. We 

address all of the comments, from both 

comment periods, in the section below. 

Comments received during both 

comment periods are posted to the 

docket. A transcript of the public 

meeting, including presentations given 

and comments delivered there, may also 

be found in the docket. 

C. Differences Between NPRM and Final 

Rule 

1. Substantive Changes 

The FAA has eliminated the 

requirement to evaluate WFD associated 

with most repairs, alterations, and 

modifications of the baseline airplane 

structure.8 The agency has also made a 

change in terminology. This final rule 

uses the term ‘‘limit of validity of the 

engineering data that supports the 

maintenance program’’ (LOV) rather 

than the term ‘‘initial operational limit.’’ 

The FAA finds that the term ‘‘limit of 

validity’’ is more appropriate than the 

term ‘‘initial operational limit’’ in 

defining the point to which an airplane 


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Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 69749 

9 72 FR 63363, November 8, 2007. 

10Certification Procedures for Products and Parts. 

11This section, which includes an applicability 

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

final rule. 

may be safely operated. The 

requirements in this final rule for 

establishing the LOV under § 26.21 are 

that it be supported by test evidence and 

analysis at a minimum and, if available, 

by service experience or service 

experience and teardown inspection 

results for those airplanes of similar 

structural design with the highest total 

accumulation of flight cycles or flight 

hours (commonly referred to as hightime airplanes). This criterion is similar 

to the criterion used in § 25.571(b). This 

final rule also clarifies how the LOV 

may be extended, using the same type 

of evaluation as that required for setting 

the LOV under § 26.21. 

In response to requests for more time, 

the FAA has extended the compliance 

dates by which design approval holders 

must establish an LOV for existing 

airplanes. Those dates vary according to 

the age of the airplanes, from 18 months 

after the effective date for the oldest 

airplanes to 60 months after the 

effective date for the newest ones. 

Additionally, the agency has extended 

the time for operators to incorporate 

LOVs into their maintenance programs. 

These dates vary with the age of the 

airplanes as well, and are 12 months 

later than the related design approval 

compliance dates, thus giving operators 

12 months to incorporate the LOV into 

their maintenance programs. Operator 

compliance dates range from 30 to 72 

months after the effective date. The FAA 

has also changed the proposed 

operational rules to correct an 

inadvertent ambiguity in the NPRM 

regarding obligations of operators of 

airplanes for which the type certificate 

holder might fail to establish an LOV as 

required. 

Another change involves applicability 

to existing transport category airplanes. 

This final rule applies to ‘‘transport 

category, turbine-powered airplanes 

with a type certificate issued after 

January 1, 1958.’’ This limitation was 

added to make applicability of today’s 

rule consistent with that of the other 

aging airplane rules. The FAA also 

added airplanes to the list of those 

excluded from the LOV requirements of 

§ 26.21 because the airplanes are not 

operated under parts 121 or 129. Either 

they are being operated under different 

parts of the Code of Federal Regulations 

(CFR) or they are not in service at this 

time. The number of these airplanes still 

operating is very small, and the 

probability of their retirement in the 

near future is high. 

2. Regulatory Evaluation Changes 

The FAA has substantially revised the 

Regulatory Evaluation for several 

reasons. One concerns differences 

between the rule as proposed and the 

final rule. For example, the requirement 

to evaluate WFD associated with 

repairs, alterations, and modifications of 

the baseline airplane structure, except 

for those mandated by airworthiness 

directives, has been eliminated from 

this final rule. Another reason concerns 

information received during the 

rulemaking process which indicated 

that some of the initial assumptions 

about benefits and costs of the rule were 

not valid. For example, initially, the 

FAA assumed that design approval 

holders would set the LOV for a specific 

airplane model at the design service 

goal for that model. However, 

subsequently, some design approval 

holders indicated that they planned to 

set the LOV 33% to 180% higher. The 

net effect of these changes has been to 

dramatically reduce the costs estimated 

for compliance with the rule. 

Our revised Regulatory Evaluation 

lists three potential sources of benefits 

of the rule, namely (1) prevention of 

accidents; (2) extension of the economic 

life of the airplane with corresponding 

revenues from that additional economic 

life; and (3) near elimination of 

emergency airworthiness directives. 

Preventing a WFD accident is 

estimated to have benefits ranging from 

$20 million to $680 million. There are 

multiple factors, however, that make it 

difficult to forecast that this rule 

absolutely would prevent accidents. 

Among them are earlier FAA 

rulemaking actions to prevent known 

fatigue problems from reoccurring. 

Similarly, although specific 

maintenance actions designed to extend 

the life of airplane structure have added 

years of service to the DC–9 fleet, 

quantification of such values for other 

models is unnecessary, given that 

benefits already exceed the nearly 

minimal costs. 

As a result, the quantified benefit of 

this final rule is based solely on the near 

elimination of emergency ADs 

pertaining to WFD. The analysis 

assumes the rule will prevent 1.5 days 

of down time associated with 

emergency ADs. 

3. New Part 26 for Design Approval 

Holders’ Airworthiness Requirements 

In the WFD proposed rule, and in 

proposals for other Aging Airplane 

Program rules, the FAA placed the 

airworthiness requirements for design 

approval holders in part 25, subpart I. 

As explained in the Enhanced 

Airworthiness Program for Airplane 

Systems/Fuel Tank Safety final rule 

(EAPAS/FTS),9 the FAA decided after 

further review and input from industry 

and foreign aviation authorities to place 

these requirements in a new part 26 and 

move the enabling regulations into part 

21.10 The FAA determined that this was 

the best course of action because it 

keeps part 25 applicable only to 

airworthiness standards for transport 

category airplanes. This is important 

because it maintains harmonization and 

compatibility among the United States, 

Canada, and the European Union 

regulatory systems. Providing references 

to part 26 in part 21 clarifies how the 

part 26 requirements will address 

existing and future design approvals. 

In creating part 26, the FAA 

renumbered the proposed sections of 

part 25, subpart I, and incorporated the 

changes discussed in this preamble. A 

table of this renumbering is shown 

below. 

FIGURE 2—TABLE SHOWING RELATIONSHIP OF PROPOSED PART 25 SUBPART I TO PART 26 FINAL RULE

Part 26 final rule Proposed part 25 

SUBPART C—Aging Airplane Safety—Widespread Fatigue Damage ...... Subpart I—Continued Airworthiness 

§ 26.5 Applicability table .............................................................................. New 11

§ 26.21 Limit of validity (LOV) ..................................................................... § 25.1807 Initial operational limit: Widespread Fatigue Damage 

(WFD). 

§ 25.1809 Changes to type certificates: Widespread Fatigue Damage 

(WFD). 

§ 26.23 Extended limit of validity (LOV) ...................................................... § 25.1811 Extended operational limit: Widespread Fatigue Damage 

(WFD) 


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FIGURE 2—TABLE SHOWING RELATIONSHIP OF PROPOSED PART 25 SUBPART I TO PART 26 FINAL RULE—Continued 

Part 26 final rule Proposed part 25 

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

4. New Subparts for Airworthiness 

Operational Rules 

The WFD NPRM was among several 

Aging Airplane Program rulemaking 

initiatives that proposed new subparts 

(subparts AA and B in parts 121 and 

129, respectively) for airworthiness 

requirements, and redesignated certain 

sections of parts 121 and 129. Since the 

EAPAS/FTS final rule was the first of 

these rulemaking initiatives to be 

codified, the new subparts and 

redesignated sections were adopted in 

that rule. Therefore, the FAA has 

removed the regulatory language and 

related discussion about these changes 

from this final rule. This final rule adds 

new sections that include WFD-related 

requirements: §§ 121.1115 and 129.115. 

D. Summary of Comments 

The FAA received comments about 

the NPRM from 40 commenters, 

including airplane manufacturers, 

operators, aviation associations, and 

others. The comments covered an array 

of topics and contained a range of 

responses. There was much support 

from airplane manufacturers, operators, 

and associations for the concept of 

precluding WFD in aging airplanes. 

There were also a number of 

recommendations for changes and 

requests for clarification. As previously 

discussed, at the December 11, 2008 

public meeting, Boeing, FedEx, and 

ATA gave presentations of their 

responses to the Technical Document. 

In addition, the FAA received 

comments about airworthiness 

requirements for design approval 

holders. We addressed many of the 

same or similar comments in the July 

2005 disposition of comments 

document to the Fuel Tank Safety 

Compliance Extension (Final Rule) and 

Aging Airplane Program Update 

(Request for Comments). We also 

explained in detail the need for these 

requirements in our July 2005 policy 

statement. As a result, the FAA will not 

revisit those comments here. 

III. Discussion of the Final Rule 

A. Overview 

1. Widespread Fatigue Damage 

Widespread fatigue damage is the 

simultaneous presence of cracks at 

multiple structural locations that are of 

sufficient size and density that the 

structure will no longer meet the 

residual strength requirements of 

14 CFR 25.571(b). This may result in 

catastrophic structural failure and loss 

of the airplane. 

Fatigue is the gradual deterioration of 

a material subjected to repeated 

structural loads. When it occurs in more 

than one location, cracks manifest 

themselves as multiple site damage or 

multiple element damage. Multiple site 

damage is the simultaneous presence of 

fatigue cracks at multiple locations that 

grow together in the same structural 

element, such as a large skin panel or 

lap joint. Multiple element damage is 

the simultaneous presence of fatigue 

cracks in similar adjacent structural 

elements, such as frames or stringers. 

Some structural elements are 

susceptible to both types of damage, and 

both types may occur at the same time. 

Cracks associated with multiple site 

damage and multiple element damage 

are initially so small that they cannot be 

reliably detected with existing 

inspection methods. Widespread fatigue 

damage is especially hazardous because 

these small, undetectable cracks in 

metallic structure can ‘‘link up’’ and 

grow very rapidly to bring about 

catastrophic failure of the structure. 

Although operators perform routine 

structural inspections to detect fatigue 

damage, fatigue cracks related to WFD 

grow so rapidly that operators cannot 

inspect susceptible structures often 

enough to detect the cracks before they 

cause structural failure. As a result, 

many of the findings of these types of 

cracks have been fortuitous: mechanics 

and others have observed fatigue cracks 

while doing other work. For example, 

cracks have been found by workers 

while stripping and painting an 

airplane. Cracks have also been found 

by mechanics conducting unrelated 

inspections of skin anomalies on the 

external fuselage; further investigation 

revealed multiple cracks in stringers 

and circumferential joints. 

In other cases, undetected multiple 

site damage in wing or fuselage 

structure has eventually led to 

catastrophic failure of the structure in 

flight. For example, wing failures have 

resulted in losses of C–130 and P4Y–2 

airplanes. Failures of aft pressure 

bulkheads have caused decompression 

of B–747, DC–9, and L–1011 airplanes. 

Concern about WFD was brought to 

the forefront of public attention in April 

1988, when an 18-foot-long section of 

the upper fuselage of a Boeing Model 

737 airplane separated from the airplane 

during flight. The airplane, operated by 

Aloha Airlines, was en route from Hilo 

to Honolulu, Hawaii, at 24,000 feet. 

Onboard were 89 passengers and 6 

crewmembers. A flight attendant died as 

a result of the accident, and eight 

passengers were injured. 

The damage to the airplane consisted 

of a total separation and loss of a major 

portion of the upper crown skin and 

other structure. The damaged area 

extended from the main cabin entrance 

door aft for about 18 feet. At the time 

of the accident, the airplane had 

accumulated 89,680 flight cycles and 

35,496 flight hours. 

In the years after the Aloha Airlines 

accident, WFD was discovered in the 

following airplanes: 

• Boeing 727: Cracking along a lap 

joint. 

In 1998, during maintenance, two 

cracks were found growing out from 

underneath the lap joint. Disassembly of 

the joint revealed a 20-inch hidden 

crack from multiple site damage on the 

lower row of rivet holes in the inner 

skin. 

• Boeing 737: Cracking along a lap 

joint. 

In July 2003, a mechanic preparing to 

paint discovered extensive multiple site 

damage with up to 10 inches of local 

link-up of cracks in one area. 

• Boeing 747: Cracking of the aft 

pressure bulkhead. 

In 2005, Boeing issued service 

information to address multiple site 

damage of the aft pressure bulkhead 

radial lap splices. The service 

information was based on analysis and 

fatigue testing of the aft pressure 

bulkhead. 

• Boeing 767: Cracking of the aft 

pressure bulkhead. 

On November 5, 2003, cracks were 

found at multiple sites common to a 

single radial lap splice during an 

inspection of the aft pressure bulkhead. 

• McDonnell Douglas DC–9: Cracking 

of the aft pressure bulkhead. 

On June 22, 2003, widespread fatigue 

damage on a DC–9 airplane led to rapid 

decompression at 25,000 feet. Later 

inspection revealed multiple site 


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12The group was initially known as the 

Airworthiness Assurance Task Force. 

13Task 3.—Widespread Fatigue Damage (WFD) of 

Repairs, Alterations, and Modifications. Provide a 

written report providing recommendations on how 

best to enable part 121 and 129 certificate holders 

of airplanes with a maximum gross take-off weight 

of greater than 75,000 pounds to assess the WFD 

characteristics of structural repairs, alterations, and 

modifications as recommended in a previous ARAC 

tasking. The written report will include a proposed 

action plan to address and/or accomplish these 

recommendations including actions that should be 

addressed in Task 4 [below]. The report is to be 

submitted to the ARAC, Transport Airplane and 

Engine Issues Group, for approval. The ARAC, 

Transport Airplane and Engine Issues Group, will 

determine as appropriate the means by which the 

action plan will be implemented. The proposed 

actions and implementation process approved by 

the ARAC, Transport Airplane and Engine Issues 

Group, will be subject to FAA concurrence. 

Published in 69 FR 26641, May 13, 2004. 

14Under 14 CFR 91.403(c), no person may operate 

an airplane unless applicable airworthiness 

limitations have been complied with. By requiring 

operators to incorporate the LOV airworthiness 

limitations developed by the design approval 

Continued 

damage with extensive link-up of 

cracks. 

• Lockheed C–130A: Fatigue cracks in 

the wing structure. 

On August 13, 1994, while 

responding to a forest fire in the 

Tahachapi Mountains near Pearblossom, 

California, the airplane experienced an 

in-flight separation of the right wing. All 

3 flight crewmembers were killed, and 

the airplane was completely destroyed. 

• Lockheed C–130A: Fatigue cracks in 

the wing structure. 

On June 17, 2002, while executing a 

fire retardant drop over a forest fire near 

Walker, California, the airplane’s wings 

folded upward at the center wing-tofuselage attachment point, and the 

airplane broke apart. All three flight 

crewmembers were killed, and the 

airplane was completely destroyed. 

• Consolidated-Vultee P4Y–2: Fatigue 

cracks in the wing structure. 

On July 18, 2002, the airplane was 

maneuvering to deliver fire retardant 

over a forest fire near Estes Park, 

Colorado, when its left wing separated 

from the airplane. Both flight 

crewmembers were killed, and the 

airplane was destroyed. An examination 

of other Consolidated-Vultee P4Y–2 

airplanes revealed that the area was 

difficult to inspect because of its 

location relative to fuselage structure. 

• Lockheed L–1011: Failure in-flight 

of the aft pressure bulkhead stringer 

attach fittings. 

In August 1995, an L–1011 airplane 

experienced a rapid decompression at 

33,000 feet. Twenty stringer end fittings 

were found severed and the aft pressure 

bulkhead was separated from the 

fuselage crown by a crack 

approximately 12 feet long. The flight 

crew was unable to maintain cabin 

pressure control until after rapid 

descent. 

• Boeing 747: Cracking of adjacent 

fuselage frames. 

In 2005, during an overnight 

maintenance visit, missing skin 

fasteners common to a fuselage frame 

were discovered in the upper deck area. 

Further inspection revealed that the 

frame was severed. Substantial cracking 

was also found in the adjacent left and 

right frames. 

• Airbus A300: Cracking of adjacent 

fuselage frames. 

In 2002, investigations conducted as a 

result of fatigue cracks found on a test 

article and later in service revealed that 

cracking of certain adjacent fuselage 

frames could result in multiple element 

damage. The determination was based 

on analysis, service experience, and 

fatigue testing. 

Since 1988, the FAA has issued 

approximately 100 airworthiness 

directives to address WFD in airplanes. 

Approximately 25 percent of these 

airworthiness directives were too urgent 

to allow the public an opportunity to 

comment in advance. These 

airworthiness directives required 

inspections, and the FAA later 

superseded the majority of them to 

expand the inspections or require 

modifications because inspections were 

not enough to preclude WFD. 

Shortly after the Aloha Airlines 

accident, the AAWG 12 was formed to 

identify procedures to ensure continued 

structural airworthiness of aging 

transport category airplanes. Basic 

approaches defined by the group and 

accepted by the FAA included 

recommending procedures to preclude 

WFD in those airplanes. When ARAC 

was formed in 1991 to provide advice 

and recommendations on safety-related 

matters to the FAA, the AAWG became 

a working group under its auspices. In 

2003 the AAWG completed its 

recommendation on WFD. 

In 2004, the FAA tasked ARAC to 

‘‘provide a written report on part 121 

and 129 certificate holders operating 

airplanes with a maximum takeoff gross 

weight of greater than 75,000 pounds to 

assess the WFD characteristics of 

structural repairs, alterations, and 

modifications as recommended in a 

previous tasking of the Aviation 

Rulemaking Advisory Committee.’’ 13

During the comment period on the 

NPRM for this final rule, the AAWG was 

working to complete Task 3, to 

recommend how an operator would 

include consideration of WFD for 

repairs, alterations, and modifications to 

airplanes operated under part 121 or 

129. 

On April 17, 2007, the AAWG 

presented its final report on Task 3 to 

ARAC. Many of the conclusions and 

recommendations in the final report are 

the same as those provided in the 

comments on the proposed rule which 

are discussed in this preamble. 

2. Final Rule 

This final rule requires actions to 

preclude WFD in transport category 

airplanes. It applies to both existing 

transport category airplanes that have a 

maximum takeoff gross weight greater 

than 75,000 pounds and to all transport 

category airplanes to be certified in the 

future, regardless of the maximum 

takeoff weight. 

Today’s rule imposes requirements on 

those holding design approvals for 

existing transport category airplanes 

that are subject to the rule. The design 

approval holders are required to 

evaluate the structural configuration of 

each model for which they hold a type 

certificate to determine its susceptibility 

to WFD and, if it is susceptible, to 

determine that WFD would not occur 

before the proposed LOV. The 

evaluation would be based on test 

evidence and analysis at a minimum 

and, if available, service experience or 

service experience and teardown 

inspection results of airplanes with a 

high number of total accumulated flight 

cycles or flight hours or both, which are 

frequently referred to as high-time 

airplanes. The evaluation would be 

performed on airplanes of similar 

structural design, accounting for 

differences in operating conditions and 

procedures. Using the results of the 

evaluation, the design approval holder 

must then establish an LOV. 

Holders of approvals for design 

changes that increase an airplane’s 

maximum takeoff gross weight to more 

than 75,000 pounds, or decrease it from 

more than 75,000 pounds to 75,000 

pounds or less after the effective date of 

the rule, must also evaluate the affected 

airplanes for WFD and establish LOVs 

for those airplanes. 

The final rule amends Appendix H to 

part 25 to require that the LOV which 

is established by the design approval 

holder be included in the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness. It also 

amends operating rules in parts 121 and 

129 to require that operators of an 

affected airplane incorporate into their 

maintenance programs an Airworthiness 

Limitations section that includes an 

LOV for that airplane. 

The amendments to parts 121 and 129 

have the effect of prohibiting operation 

of an airplane beyond its LOV.14 For 


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holders under this rule, this final rule makes those 

LOVs applicable to the affected airplanes, and 

§ 91.403(c) requires operators to comply with them. 

15The elite eleven are the original models 

considered under the Aging Aircraft Program. These 

were airplanes over 75,000 pounds, operating under 

part 121 or 129, that were at a greater risk for agerelated structural problems because they had hightime airplanes that were near or over their design 

service goals. They include the Airbus A300, 

Boeing 707/720, Boeing 727, certain Boeing 737s, 

certain Boeing 747s, McDonald Douglas DC–8, DC– 

9/MD–80, and DC–10, Lockheed L–1011, Fokker F– 

28, and the BAC 1–11. 

transport airplane designs developed in 

the future, the LOV will be included in 

the airplane’s airworthiness limitations 

and will apply regardless of how or by 

whom the airplane is operated. 

However, the final rule allows any 

person to extend the LOV for an 

airplane (if the person can demonstrate 

that it will be free of WFD up to the 

extended LOV) and to develop a 

maintenance program that supports the 

extended limit. Thereafter, the operator 

must incorporate the extended LOV and 

the associated maintenance actions into 

the Airworthiness Limitations section of 

its Instructions for Continued 

Airworthiness and may not operate the 

airplane beyond that limit. 

The remainder of this section of the 

preamble discusses specific comments 

received. 

B. Requests for Deferral or Withdrawal 

of Rule 

The FAA received a number of 

comments that rulemaking to preclude 

WFD was not warranted and that the 

rule, as proposed, should be deferred or 

withdrawn. Commenters included 

United Parcel Service, American 

Airlines, FedEx, Cargo Airline 

Association (CAA), National Air Carrier 

Association (NACA), Lynden Air Cargo, 

ATA, Northwest Airlines, Transport 

Aircraft Technical Services, and 

Continental Airlines. 

1. Safety Benefits Don’t Justify Rule 

American Airlines, ATA, and Lynden 

Air Cargo commented that the rule was 

not justified in terms of safety. They 

pointed out that there has been no 

catastrophic accident directly 

attributable to WFD since the Aloha 

Airlines accident in 1988 and that the 

National Transportation Safety Board 

found that WFD was a contributory 

factor, but not the sole factor, in that 

accident. 

In contrast, Boeing commented that 

issuance of this final rule would cast a 

broad safety net on airframe structural 

performance for those types of details 

the industry has determined may be 

susceptible to WFD. Boeing said this 

final rule would provide for the 

establishment of safe operational limits 

and the maintenance actions necessary 

to preclude WFD prior to reaching those 

limits. 

There have been several instances of 

major structural failure in flight due to 

fatigue. Therefore the potential for 

catastrophic structural failure is 

significant. The FAA considers that this 

rulemaking is essential to prevent future 

accidents or incidents. In the past, 

industry practice for new airplane 

design certification has been to develop 

some level of understanding of 

structural fatigue characteristics up to 

the design service goal, but not beyond 

it. A significant number of airplanes 

being operated currently have already 

accumulated a number of flight cycles 

or flight hours greater than the original 

design service goal. As the existing fleet 

continues to age, the number of such 

airplanes will increase. Structural 

fatigue characteristics of airplanes are 

understood only up to a certain point 

consistent with the analyses performed 

and the amount of testing accomplished. 

Operation beyond this point without 

further engineering evaluation should 

not be allowed because, in the absence 

of intervention, the likelihood of WFD 

increases with the airplane’s time in 

service. 

2. Existing Programs Serve Purpose of 

Rule 

United Parcel Service, American 

Airlines, the CAA, ATA, Transport 

Aircraft Technical Services Company, 

and Lynden Air Cargo recommended 

that the proposed rule be withdrawn 

because existing programs serve the 

same purpose as an inspection program 

for WFD. These commenters were 

referring to existing elements of the 

Aging Aircraft Program, which resulted 

from the Aloha Airlines accident. They 

include the following: 

• Supplemental Structural Inspection 

Program, 

• Mandatory Modification Program, 

• Repair Assessment Program, 

• Corrosion Prevention and Control 

Program. 

In addition, the FAA has issued 

airworthiness directives to address 

aging airplane safety concerns. Lynden 

Air Cargo and Transport Aircraft 

Technical Services Company said that 

the Aloha Airlines accident might not 

have happened if proper 

accomplishment and FAA oversight of 

the maintenance program had been 

performed. 

The FAA recognizes that the four 

elements of the Aging Aircraft Program 

have some inherent ability to detect 

multiple site damage or multiple 

element damage, but existing inspection 

methods cannot detect such damage 

reliably. As acknowledged by some of 

the commenters, these four elements 

were not specifically designed to 

address WFD; they were designed as 

elements of an overall program to 

address structural degradation on the 

pre-Amendment 25–45 airplanes over 

75,000 pounds maximum takeoff gross 

weight, commonly known as the ‘‘elite 

eleven.’’ 15 This final rule, which 

specifically addresses WFD, is intended 

to be the last element of the overall 

Aging Aircraft Program. 

The AAWG, of which several of these 

commenters were members, recognized 

the inadequacy of existing programs to 

address WFD when it submitted its 

recommendation for FAA rulemaking 

on this subject in 2001. The 

recommendation included the following 

discussion: 

Regulatory and industry experts agree that, 

as the transport airplane fleet continues to 

age, eventually WFD is inevitable. Long-term 

reliance on existing maintenance programs, 

even those that incorporate the latest 

mandatory changes introduced to combat 

aging, creates an unacceptable risk of agerelated accidents. Even with the existing 

aging airplane program for large transports in 

place, WFD can and does occur in the fleet. 

Therefore, the FAA has determined that, at 

a certain point of an airplane’s life, the 

existing aging airplane program is not 

sufficient to ensure the continued 

airworthiness of that fleet of airplanes. 

As discussed previously, the FAA has 

issued approximately 100 airworthiness 

directives to address unsafe conditions 

due to WFD on a number of airplanes. 

Airworthiness directives are reactive in 

the sense that the agency issues them 

only after determining that an unsafe 

condition exists in one or more 

airplanes and is likely to exist or to 

develop in other airplanes of the same 

type design. Typically, unsafe 

conditions associated with WFD or its 

precursors have been discovered largely 

by chance by people performing 

unrelated airplane maintenance. 

The FAA concludes that the agency 

cannot rely on existing programs— 

including issuing airworthiness 

directives if the FAA learns of an unsafe 

condition—to detect or address WFD 

that occurs in aging airplanes. These 

programs do not obviate the need for a 

rule to prevent catastrophic accidents 

due to WFD. This final rule specifically 

addresses WFD and its precursors by 

requiring design approval holders to 

evaluate their airplanes for WFD to 

prevent development of unsafe 

conditions. 

Although maintenance program 

oversight can always be improved, the 


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Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 69753 

fact remains that WFD is difficult, if not 

impossible, to detect. Small cracks that 

can lead to WFD often cannot be 

detected until they suddenly increase in 

size and ‘‘link up,’’ to cause catastrophic 

damage. Dramatic crack growth can 

occur quite suddenly and quickly, after 

being undetectable for long periods of 

time. That is why maintenance 

inspections cannot be relied on to detect 

and repair such cracking. Airplane 

maintenance programs include 

inspections that are designed to detect 

obvious damage and irregularities. 

WFD, by its nature, is usually hidden, 

and not readily detectable. Discovery of 

WFD in some airplanes by mechanics 

has been a purely random occurrence, 

where damage detected was the result of 

WFD that had progressed to the point of 

failure of structural members. An 

example is discovery of WFD on a 

Boeing 747, with adjacent frame 

cracking and separations. It was 

detected because of loose rivets on the 

skin. Mechanics happened upon the 

WFD damage by chance, because 

inspections had not uncovered any 

problem. Improving a maintenance 

program by adding or modifying 

inspections would not necessarily have 

the effect of improving detection of 

WFD. In general, the only way to 

address WFD is by modifying or 

replacing structure. 

The National Transportation Safety 

Board report stated the following: 

It is probable that numerous small fatigue 

cracks in the lap joint along S–10L joined to 

form a large crack (or cracks) similar to the 

crack at S–10L that a passenger saw when 

boarding the accident flight. The damage 

discovered on the accident airplane, damage 

on other airplanes in the Aloha Airlines fleet, 

fatigue striation growth rates, and the service 

history of the B–737 lap joint disbond 

problem led the Safety Board to conclude 

that, at the time of the accident, numerous 

fatigue cracks in the fuselage skin lap joint 

along the S–10L linked up quickly to cause 

catastrophic failure of the large section of the 

fuselage. 

The AAWG worked on various 

solutions to the safety problems 

encountered by aging airplanes and was 

instrumental in developing the four 

programs listed earlier in this 

document. However, they decided that 

additional actions were needed to 

preclude WFD in airplanes, and the 

steps they outlined included: 

• Setting limits of validity of the 

maintenance program. 

• Deciding whether WFD can be 

inspected for, and, if so, for how long 

such inspections would be effective. 

• Defining when WFD-susceptible 

structure should be modified or 

replaced. 

Lynden Air Cargo stated that it 

supported an approach that used 

airworthiness directives to address 

WFD-susceptible structural components 

instead of an LOV approach for the 

entire airplane. Lynden Air Cargo 

further stated that the unique design of 

the L–382G allows for the whole 

airframe to be renewed by replacing 

WFD-susceptible sections (e.g., center 

wing and outer wing). 

The FAA agrees with Lynden Air 

Cargo that WFD-susceptible structure 

can be replaced when the engineering 

data determines it should be replaced to 

preclude WFD. However, as airplanes 

age, other areas may also need to be 

replaced. The only way to determine 

that is to evaluate the engineering data 

(analyses, tests, service experience) for 

the entire airplane. Without the LOV, 

the operational life of an airplane is 

undefined. As a result, the list of areas 

to inspect, modify, replace, or any 

combination of these may be extensive, 

since the data would need to 

substantiate an indefinite life. 

3. Divide Rule into Two 

FedEx, Northwest Airlines, 

Continental Airlines, NACA, and ATA 

stated that the proposed draft final rule 

does not allow the public an 

opportunity to comment on the LOVs 

that design approval holders propose as 

compliance to part 26. They suggested 

the rule be divided into two rules: one 

for design approval holders and one for 

operators. The commenters noted that 

this two-step process would provide the 

public the opportunity to comment on 

design approval holders’ proposed 

LOVs. Deferral of the operator rule 

would also allow for public comment on 

the WFD maintenance actions at the 

same time LOVs are established. In 

support of this approach, FedEx 

specifically argued that the incremental 

costs for the part 26 work to design 

approval holders is minimal, as design 

approval holders have confirmed in 

their comments to this docket. 

The FAA has determined that 

complementary, concurrent 

requirements for design approval 

holders and operators are necessary to 

achieve the safety benefits of the 

proposed rule in a timely manner. 

Although design approval holders 

would be required to develop LOVs for 

affected airplanes under part 26, the 

safety benefit for this rulemaking 

initiative is not met until operators 

incorporate LOVs and only operate 

airplanes up to the point in time for 

which it can be shown that the airplane 

will be free from WFD. Until design 

approval holders actually comply with 

part 26, it’s not possible to identify the 

precise LOV for any particular airplane. 

However, operators have had adequate 

general notice of the objectives of this 

rulemaking and the proposed methods 

for achieving those objectives in the 

form of the design approval holders’ 

anticipated LOVs. Since the public 

meeting, both Boeing and Airbus have 

provided revised information about 

where they anticipate those LOVs will 

be set. 

If additional, multiple rulemakings 

are necessary to require operators to 

incorporate LOVs into their 

maintenance programs, there is a risk of 

airplanes exceeding LOVs before those 

rules become effective. The FAA 

concludes that, to achieve our safety 

objectives, design approval holders and 

operators must have a shared 

responsibility on certain safety issues 

affecting the existing fleet. We also 

conclude, from reviews such as the 

Commercial Airplane Certification 

Process Study (March 2002), that we 

need to facilitate more effective 

communication of safety information 

between design approval holders and 

operators. As both technology and 

airworthiness issues become more 

complex, certain fleet-wide safety issues 

require the FAA to implement 

complementary requirements for design 

approval holders and operators, when 

appropriate. 

C. Concept of Operational Limits 

This final rule requires design 

approval holders to establish limits of 

validity of the engineering data that 

supports the maintenance program. The 

proposed rule would have required that 

design approval holders establish initial 

operational limits beyond which 

airplanes may not be operated. The 

initial operational limit would be based 

on the demonstration of freedom from 

WFD up to that initial operational limit. 

Several commenters supported the 

concept of early detection of WFD for 

aging airplanes but opposed the 

requirement to establish initial 

operational limits beyond which the 

airplanes could not be operated. These 

commenters equated establishment of 

such limits with mandatory retirement 

of airplanes and suggested that, instead, 

the FAA enhance current maintenance 

programs and practices. 

1. Requests for Requiring Maintenance 

Programs Instead 

An aircraft leasing and trading 

company named AWAS recommended 

that an inspection-based maintenance 

program become mandatory as airplanes 

reach their design service goal or their 

operational limit. Lynden Air Cargo 

stated that there are better, less intrusive 


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69754 Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 

methods to achieve early detection of 

WFD than the ‘‘application of onerous 

initial and extended operational limits.’’ 

According to the commenter, these 

methods include proper establishment, 

accomplishment, and enforcement of 

current airplane maintenance programs, 

such as the maintenance programs 

required by parts 121 and 135. Lynden 

Air Cargo said it is continuously 

revising its Continuous Airworthiness 

Maintenance Program to include a 

design approval holder inspection 

program of Structural Significant Items 

and recommended structural service 

bulletins. 

These commenters raise some of the 

same issues as did those who opposed 

the rule altogether. They suggest that 

current programs for aging airplanes or 

new maintenance programs to detect 

WFD—along with issuance of 

airworthiness directives when WFD is 

detected—would obviate the need for 

setting operational limits. 

As stated in the NPRM, the structural 

fatigue characteristics of airplanes are 

only understood up to a point in time 

consistent with the analyses performed 

and amount of testing accomplished. 

Structural maintenance programs are 

designed with this in mind. The LOV is 

defined as the limit of the engineering 

data that supports the structural 

maintenance program and the current 

regulatory maintenance requirements of 

parts 121 and 129 do not require that 

WFD be specifically addressed. 

Also as discussed previously, WFD 

cannot be detected reliably by existing 

inspection methods. Therefore, the FAA 

considers that WFD in existing airplanes 

needs to be proactively addressed by 

requiring design approval holders to use 

relevant engineering data to project the 

number of flight cycles or flight hours 

or both which the airplanes can 

accumulate without incurring WFD. The 

engineering data may include the 

evaluation and establishment of 

maintenance actions that address WFD. 

2. Single Retirement Point for a Model 

The Modification and Replacement 

Parts Association (MARPA) opposed a 

single, mandatory retirement age for 

airplanes because of the ‘‘vast 

differences possible between aircraft 

models, missions, and maintenance.’’ In 

a similar vein, a company named Safair, 

which is based in South Africa, 

commented that the difference in 

structural integrity of aging airframes 

lies in their use and abuse during their 

lives and is largely dependent on the 

specific load factors to which the 

airframe is subjected. Safair added that 

the proposed rule may be based on 

inadequate technical evaluation of the 

actual operational experience, 

considering the number of older aircraft 

that have been safely operated well 

beyond the actual cycles listed in the 

proposed rule. 

It is true that there may be differences 

between airplanes of the same model 

which reflect differences in use and 

maintenance by different operators. 

When manufacturers design an airplane, 

they consider the various ways it may 

be used, and they develop a ‘‘mission 

profile’’ to account for the different 

loads the airplane may be subjected to 

that must be addressed in their design. 

In setting the LOV, manufacturers will 

take this information into account, along 

with service experience of the particular 

airplane model and fatigue test 

evidence. The LOV must apply to an 

airplane model, because it is based on 

analysis of the service experience of the 

entire fleet of affected airplanes. 

3. Potentially Adverse Effect on Safety 

Lynden Air Cargo, MARPA, and the 

airplane leasing and trading company 

AWAS also suggested that mandatory 

retirement of airplanes may have an 

adverse effect on safety which has not 

been considered by the FAA. 

Specifically, AWAS envisioned that 

operators of airplanes approaching their 

operational limit may perform minimal 

maintenance on airframes to save 

money. MARPA said that mandatory 

retirement could have a negative 

influence on the degree and timing of 

safety-related investment, particularly 

as the aircraft nears its ‘‘throwaway 

years.’’ The owner and operator may not 

intend to be unsafe, suggested MARPA, 

but the question ‘‘Why invest now?’’ will 

arise. A similar comment from Lynden 

Air Cargo anticipated that operators ‘‘are 

unlikely to apply the same level of 

maintenance effort for an airplane 1,000 

flight hours from the scrap heap as one 

with 20,000 flight hours remaining.’’ 

Under existing operating rules, 

operators are responsible for 

maintaining their airplanes in an 

airworthy condition. These maintenance 

requirements apply equally to new and 

old airplanes. Even without this final 

rule, operators have always planned to 

retire airplanes, and service experience 

indicates that they generally continue to 

maintain them safely up to that point. 

The purpose of this final rule is to 

ensure that airplanes are retired before 

the point where they can no longer be 

safely maintained with respect to WFD. 

D. Change in Terminology (Initial 

Operational Limit to LOV) 

1. Rationale for the Term LOV 

The NPRM proposed to establish an 

initial operational limit, expressed in 

flight cycles, flight hours, or both, 

beyond which an airplane could not be 

operated. Several commenters, 

including industry representatives on 

the AAWG and Boeing, objected to this 

term and suggested that instead the FAA 

refer to the ‘‘limit of validity of the 

engineering data that supports the 

maintenance program,’’ or LOV. This 

final rule uses the term LOV to express 

the point beyond which an airplane 

cannot be operated (unless an extended 

LOV has been approved). 

In recommending that the FAA refer 

to the ‘‘limit of validity of the 

engineering data that supports the 

maintenance program,’’ or LOV, 

industry representatives on the AAWG 

stated that the term ‘‘initial operational 

limit’’ implies that the use of an airplane 

is limited in operation. According to the 

commenters, the limitation is actually 

based on the engineering knowledge of 

the structural behavior of the airplane 

model and is intended to ensure that 

required inspections are sufficient to 

ensure safe operations until a certain 

number of flight cycles or flight hours 

or both have been reached. The 

engineering data that support such 

inspection requirements change with 

time due to knowledge gained from inservice experience and additional 

testing. 

Boeing defined LOV as the point 

(usually measured in flight cycles) in 

the structural life of an airplane where 

the engineering basis for the 

maintenance actions contained in the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness is no longer a valid 

predictor of future structural behavior. 

Our intent, as stated in the NPRM, 

was to ensure that large transport 

category airplanes not be operated 

beyond their initial operational limit, 

unless operators had incorporated an 

extended operational limit and the 

service information necessary to support 

it into their maintenance programs. Just 

as the structural fatigue characteristics 

of airplanes are understood only up to 

a point consistent with analyses 

performed, testing accomplished, and 

in-service experience gained, the 

engineering data used to develop 

inspections and modifications to 

preclude WFD is valid only to a certain 

point. 

For these reasons, the FAA finds the 

term ‘‘limit of validity’’ more appropriate 

than the term ‘‘initial operational limit’’ 


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16March 31, 1998, 63 FR 15708. 17 72 FR 70486, December 12, 2007. 

in defining the point to which an 

airplane may be safely operated in 

relation to WFD. The LOV is 

substantiated by test evidence and 

analysis. This test evidence and analysis 

may be augmented by service 

experience, or by service experience and 

teardown inspection results, if available. 

The service experience and teardown 

inspection results must be for high-time 

airplanes of similar structural design, 

accounting for differences in operating 

conditions and procedures. Additional 

engineering data would be necessary to 

support operation of an airplane beyond 

the LOV. The legal effect of the terms 

initial operational limit and limit of 

validity is the same. Therefore, this final 

rule uses the term limit of validity 

instead of the term initial operational 

limit. 

2. Refer to the Structural Maintenance 

Program 

Airbus stated that the term limit of 

validity of the engineering data that 

supports the maintenance program 

should be revised for clarification. 

Because WFD is addressed by 

performing inspections or modifications 

or replacements of airframe structure, 

the phrase ‘‘maintenance program’’ 

should be changed to ‘‘structural 

maintenance program.’’ 

The FAA agrees with Airbus and that 

change is reflected here. 

E. Repairs, Alterations, and 

Modifications 

This final rule requires design 

approval holders to establish LOVs for 

airplane models subject to this rule. 

However, it does not include separate 

requirements to address WFD for 

repairs, alterations, and modifications to 

those airplanes or to develop guidelines 

to address repairs, alterations, or 

modifications. The proposed rule would 

have required evaluation of repairs, 

alterations, and modifications of the 

baseline structure of the airplane. The 

proposed rule would have also required 

development of guidelines for repairs, 

alterations, and modifications. Persons 

repairing or altering airplanes certified 

to § 25.571 at Amendment 25–96 or later 

are already required to show the repair 

or alteration to be free from WFD up to 

the airplane’s design service goal. This 

requirement has not changed since 

adoption of Amendment 25–96 in 

1998.16

1. Whether Repairs, Alterations, and 

Modifications Pose WFD Risks 

The Technical Document, discussed 

earlier, stated that the FAA, in response 

to comments, had removed the 

proposed requirements for repairs, 

alterations, and modifications. In 

response to the Technical Document, 

Lynden Air Cargo, Northwest Airlines, 

ATA, Continental Airlines, and FedEx 

stated that they support removal of 

requirements for repairs, alterations, 

and modifications from the draft final 

rule. These commenters stated that 

repairs, alterations, and modifications 

present a reduced risk for WFD because 

they will be surveyed and assessed 

under the Aging Airplane Safety Final 

Rule and the Damage Tolerance Data for 

Repairs and Alterations Rule (hereafter 

referred to as the Damage Tolerance 

Data Rule).17 Commenters often used 

the term ‘‘Aging Airplane Safety Rule’’ to 

refer to the Damage Tolerance Data Rule 

or the Aging Airplane Safety Final Rule, 

or both. In instances where this occurs, 

to avoid confusion, the name of the 

specific rule has been inserted in 

parentheses. 

These commenters expressed the 

belief that a new WFD requirement for 

repairs, alterations, and modifications is 

unnecessary because of these other 

requirements, which are already in 

place. Lynden Air Cargo stated that, 

although it supports removal of 

requirements to evaluate repairs, 

alterations, and modifications for WFD 

because the Damage Tolerance Data 

Rule already adequately addresses them, 

it does not understand how each design 

approval holder is going to establish the 

validity of its maintenance program 

without validating the repairs and 

alterations it has established under that 

program. Northwest Airlines said that it 

supported the conclusion of the AAWG 

that the costs of including repairs, 

alterations, and modifications in the 

rule outweighed the benefits that such 

a requirement would have. 

Boeing, Airbus, and the European 

Aviation Safety Agency (EASA) said the 

FAA should reconsider its decision to 

remove from the rule the requirements 

for evaluating certain repairs, 

alterations, and modifications. All three 

commenters stated that removing those 

requirements could affect safety because 

certain alterations could affect the LOV 

and the structural maintenance program 

that supports the LOV. An example of 

an alteration that could affect the LOV 

and structural maintenance program, 

the commenter maintained, is one that 

would cause a global loading increase, 

such as an alteration allowing a higher 

cabin differential pressure. Airbus 

stated that, although the Changed 

Product Rule (14 CFR 21.101) may 

address future alterations and 

modifications, it does not cover existing 

ones. 

Boeing recommended that the FAA 

revise subpart E of part 26, the Damage 

Tolerance Data Rule, for repairs and 

alterations, and §§ 121.1109 and 

129.109, the Aging Airplane Safety 

Final Rule, to include requirements for 

evaluating repairs, alterations, and 

modifications for WFD. Boeing’s 

recommendation contains two parts. 

First, it requests that the FAA extend 

the compliance date for both rules by 18 

months after the effective date of the 

WFD rule. Second, it says the FAA 

should incorporate the 2007 ARAC 

recommendations on evaluating repairs, 

alterations, and modifications into those 

rules. 

Boeing, Airbus, EASA, and the Allied 

Pilots Association (APA) stated that 

certain repairs, alterations, and 

modifications need to be evaluated for 

WFD. APA stated that eliminating the 

requirement to evaluate WFD associated 

with most repairs, alterations and 

modifications from the final rule is 

risky, because many high-time airplanes 

fall into this category and will not have 

any current analysis done on their 

modified airframes. 

In its final report to ARAC concerning 

Task No. 3, the AAWG stated that it has 

reviewed the accident record and has 

observed that—while there is a 

technical possibility of a WFD-related 

accident involving a repair or 

alteration—there are no recorded 

accidents attributed to WFD occurring 

in properly-installed repairs or 

alterations. The group added that a 

review of certain repairs, alterations, 

and modifications is necessary, because 

some of them have the potential to 

develop WFD. 

The FAA agrees with the commenters 

that some repairs, alterations, and 

modifications may pose a risk of 

developing WFD. However, the risk 

appears to be less than that for baseline 

airplane structure because all adverse 

service experience to date has been 

limited to baseline airplane structure. 

Type certificate holders design repairs, 

alterations, and modifications using the 

same design philosophies and load 

cases as for baseline airplane structure. 

As they do with the baseline airplane 

structure, type certificate holders reevaluate their repairs, alterations, and 

modifications as service experience is 

gained. Therefore, these repairs, 

alterations, and modifications should be 

acceptable up to the LOV. 

The repairs, alterations, and 

modifications developed by persons 

other than type certificate holders may 

present a slightly greater risk, because 

those persons typically do not have the 


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18Task Area II, Project I, Survey of Transport 

Airplane Structural Repairs and Alterations, 

Statement of Work 064070723–1, dated October 23, 

2007; FAA William J. Hughes Technical Center, 

Atlantic City, New Jersey. The Scope of Work for 

this research is available in the docket for this rule. 

19 71 FR 20574, April 21, 2006. 

20The companies represented are Boeing, Airbus, 

American Airlines, Northwest Airlines, US 

Airways, United Parcel Service, FedEx, ABX 

(previously known as Airborne Express), 

Continental Airlines, Japan Air Lines, United 

Airlines, and British Airways. Although the 

comments are not representative of the views of 

other members of the AAWG, including national 

authorities, for simplicity the source of these 

comments is identified hereafter as ‘‘industry 

representatives on the AAWG.’’ 

21The Damage Tolerance Data Rule is 

Amendment 26–1 and the Aging Airplane Safety 

Final Rule is Amendment 121–337 to the CFR. 

22October 5, 1978, 43 FR 46238. 

23Test evidence comprises full fatigue testing up 

to at least two times the proposed design service 

goal and may include, for derivative airplanes, 

analysis, service experience, or service experience 

and results of tear-down inspections of high-time 

airplanes, if available. 

type certificate holder’s data or 

expertise. Although those repairs, 

alterations, and modifications may pose 

a higher risk for developing WFD, there 

are no recorded accidents attributed to 

WFD occurring in these repairs, 

alterations, and modifications. Nor have 

there been a significant number of 

findings of multiple site or element 

damage associated with them. 

The FAA is funding additional 

research at the agency’s Technical 

Center to get a better understanding of 

these risks and how to address them.18

This research includes conducting a 

field survey of repairs, alterations, and 

modifications on high-time airplanes to 

document the existing configurations. 

The research also includes removing 

some repairs, alterations, and 

modifications to further evaluate their 

condition. In some cases, testing of 

particular structure may be performed to 

obtain data for calibration and 

validation of methodologies for 

predicting WFD. If this research 

demonstrates that additional actions are 

needed to address risks for repairs, 

alterations, and modifications, the FAA 

will consider further rulemaking. 

Based on the above, the FAA has reevaluated the NPRM and determined 

that the proposed requirements to 

address repairs, alterations, and 

modifications should be removed from 

the final rule. 

2. Relationship to Damage Tolerance 

Requirements (§ 25.571) 

a. Pre-Amendment 25–96 Airplanes 

The FAA received numerous 

comments requesting that the proposed 

requirements for repairs, alterations, 

and modifications in the NPRM and the 

related proposed requirements of the 

Damage Tolerance Data Rule NPRM 19

be combined and aligned in a single 

rulemaking. These commenters 

included industry representatives who 

are members of the AAWG,20 the ATA, 

Boeing, Airbus, Cessna, and American 

Airlines. They were concerned that 

separate requirements for repairs, 

alterations, and modifications in the 

Aging Airplane Safety Rule (the Damage 

Tolerance Data Rule) and the NPRM for 

this rule would require duplicative 

efforts. 

Given the proposed timeframes for 

compliance and the shortage of 

qualified industry resources to perform 

the required analyses, the commenters 

suggested that separate requirements are 

unnecessary and could not be 

accomplished within the proposed 

compliance times. The industry 

representatives on the AAWG stated 

that there are fewer than 50 persons in 

industry who are qualified to perform 

damage tolerance and WFD assessments 

and most of them are employed by the 

major design approval holders. 

The AAWG stated in its final report 

on Task 3 that existing alterations and 

repairs would receive a damage 

tolerance assessment under the Aging 

Airplane Safety Final Rule (developed 

under the Damage Tolerance Data 

Rule).21 The report indicated that this 

should provide an improved level of 

safety because repairs, alterations, and 

modifications would be surveyed and 

evaluated. The AAWG recommended 

that repairs not be re-reviewed for WFD 

if they had already been reviewed for 

damage tolerance. 

Since adoption of Amendment 25–45 

in 1978,22 the damage tolerance 

provisions of § 25.571 have required 

consideration of damage at multiple 

sites, the precursor for WFD. While 

recent efforts on damage tolerance have 

focused on localized cracking, in most 

cases the design approval holders have 

addressed multiple site damage in their 

design of both baseline structure and of 

repairs, alterations, and modifications, 

even if indirectly. As a result, the FAA 

agrees that damage tolerance assessment 

of repairs, alterations, and modifications 

should provide some degree of 

mitigation of risk, even though the focus 

of the assessments has been on 

developing inspections, and inspections 

cannot reliably detect WFD. 

The FAA recognizes the scarcity of 

expert resources in the area of damage 

tolerance and WFD. By removing 

requirements to address repairs, 

alterations, and modifications from this 

final rule, the agency is allowing those 

resources to be focused on meeting the 

compliance dates for the Damage 

Tolerance Data Rule and addressing 

WFD in baseline airplane structure, 

where the risks are greater. The FAA has 

recently been providing training to its 

designees and to industry members 

regarding compliance with § 25.571 and 

the Damage Tolerance Data and Aging 

Airplane Safety Final Rules. In that 

training, we have provided additional 

guidance on performing a damagetolerance evaluation to assess damage at 

multiple sites. Adoption of this final 

rule should also result in significant 

commitments from industry to develop 

resources with this expertise. 

b. Airplanes Certified to Amendment 

25–96 or Later 

The Technical Document described 

the agency’s intent to remove 

requirements for evaluating repairs, 

alterations, and modifications for WFD. 

Airbus requested that the FAA clarify 

that today’s final rule will not negate 

those requirements for persons making 

repairs, alterations, or modifications to 

their airplanes certified to Amendment 

25–96. As another option, Airbus 

requested that the WFD rule 

applicability not include Amendment 

25–96 or later airplanes, because those 

airplanes are already certified to WFD 

requirements. 

The FAA agrees that clarification is 

necessary for airplanes certified to 

§ 25.571, Amendment 25–96 or later. 

Amendment 25–96 revised § 25.571 to 

require that full-scale fatigue test 

evidence 23 be developed to show 

freedom from WFD up to an airplane 

model’s design service goal. Also, any 

person performing a repair, alteration, 

or modification to those airplanes must 

address WFD for the repair, alteration, 

or modification, and show compliance 

with those requirements. The newest 

airplanes, like the Airbus A–380, are 

certified to Amendment 25–96, but most 

other airplanes operating today are 

certified to an Amendment level prior to 

25–96, and thus would not be required 

to comply with those WFD 

requirements. They would, however, be 

required to comply with the 

requirements of the Damage Tolerance 

Data Rule. 

For today’s rule, § 25.571 and 

Appendix H to Part 25 require that 

applicants show an airplane model to be 

free from WFD up to the LOV instead of 

to the design service goal. Unlike 

Amendment 25–96, which did not 

require the design service goal to be 

included in the Airworthiness 

Limitations section, this final rule 

mandates LOV placement in the 

Airworthiness Limitations section. The 


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24Task 4.—Model Specific Programs. 

Oversee the Structural Task Group (STG) 

activities that will be coordinated for each 

applicable airplane model by the respective type 

certificate holders and part 121 and 129 certificate 

holders. These STG activities will involve the 

development of model specific approaches for 

compliance with §§ 121.370a and 129.16 under the 

guidance material supplied in Task 1. As part of 

this tasking, the AAWG will identify those airplane 

models that do not have an STG, and will assess 

the need to form one (based on industry benefit). 

For those airplane models that will need to form an 

STG, the AAWG will initiate the coordination 

required to form the STG with the respective type 

certificate holder and/or part 121 and 129 certificate 

holders. In addition, the AAWG will support 

implementation of the action plan to address 

recommendations made in tasks 2 and 3 as 

determined necessary by the ARAC, Transport 

Airplane and Engine Issues Group, and concurred 

with by the FAA. 

requirements of today’s rule are similar 

to those of Amendment 25–96. Any 

person who repairs, alters, or modifies 

any airplane certified under today’s rule 

must show that repair, alteration, or 

modification to be free from WFD up to 

the airplane’s LOV. 

3. Guidelines for Repairs, Alterations, 

and Modifications 

Industry representatives on the 

AAWG and several other commenters 

recommended that proposed 

§ 25.1807(g), along with §§ 25.1809 and 

25.1813, be withheld until the working 

group completed relevant taskings from 

ARAC. In particular, the commenters 

stated that the guidelines in 

§ 25.1807(g)(3) could not be technically 

accomplished because the design 

approval holders do not have the data 

or knowledge necessary to provide 

guidance for all possible repair or 

alteration configurations. 

Boeing and Airbus commented that 

they could support WFD guidelines that 

are limited in scope. The guidelines 

should identify structure prone to 

development of WFD and provide 

processes and procedures by which 

operators can access valid data for 

complying with the rule. But these 

commenters said that such guidelines 

should not attempt to describe methods 

for determining when WFD is likely to 

occur or for developing service 

information to preclude WFD. The 

commenters objected to providing 

guidelines as defined under proposed 

§ 25.1807(g)(3) because design approval 

holders would have no control over how 

the guidelines would be used. They 

further stated that such guidelines could 

expose design approval holders to 

potential liability if they are applied 

incorrectly. 

When the FAA issued the NPRM, the 

agency was relying on the AAWG, 

under an ARAC tasking, to identify a 

means of compliance that would be 

practical for both design approval 

holders and operators. Although ARAC 

did not provide detailed 

recommendations for developing 

guidelines, it did provide a general 

approach. 

Requirements pertaining to repairs, 

alterations, and modifications were 

included in the proposed rule to ensure 

that they would not degrade the level of 

safety provided by the design approval 

holder’s compliance with the rule. 

Although the FAA has removed these 

proposed requirements from the final 

rule, the agency is engaged with 

industry in a number of activities to 

address these concerns. 

For repairs, the AAWG recommended 

in its final report on Task 3 that each 

design approval holder update its 

publications (e.g., structural repair 

manuals, service bulletins, and repair 

assessment guidelines) to include 

instructions for inspecting and, if 

necessary, modifying structure 

susceptible to WFD. This update should 

occur by the time the design approval 

holder has established the LOV for an 

airplane model. The AAWG 

recommended that design approval 

holders update their service documents 

for WFD at the same time they are 

revising these documents for the Aging 

Airplane Safety Rule (the Damage 

Tolerance Data Rule) if the WFD data 

are available. The FAA expects that 

design approval holders will fulfill this 

recommendation. To the extent that 

design approval holders update their 

service documents for WFD, operators, 

when complying with requirements of 

the Aging Airplane Safety Final Rule by 

using those updated service documents 

for repairs, will be addressing the WFD 

risks for these repairs. In addition, 

§ 25.571 already requires consideration 

of the potential for WFD for repairs to 

airplanes certified to Amendment 25–96 

or later. 

For alterations, the AAWG surveyed 

642 supplemental type certificates. Out 

of the 642, they identified only 14 

alterations and modifications that 

would require assessment for WFD. 

Based on this, they suggested that the 

FAA review these types of existing 

alterations to determine whether any 

action is necessary. The Task 3 report 

did not specifically recommend that 

design approval holders address their 

alterations for WFD. However, recent 

meetings conducted by certain design 

approval holders indicate that they 

intend to address their own alterations 

and modifications for WFD in addition 

to repairs in the Task 4 24 structures task 

group activity. The majority of transport 

airplanes operating in the U.S. that are 

subject to this final rule will be 

addressed by these design approval 

holders. We anticipate that other design 

approval holders will also review their 

alterations and modifications for WFD. 

While these activities will not address 

alterations and modifications developed 

by other persons (including 

supplemental type certificate holders), 

as stated earlier, the FAA is conducting 

research to get a better understanding of 

the risks that repairs, alterations, and 

modifications may pose for developing 

WFD and whether they need to be 

assessed for WFD. If the FAA 

determines that the risks are 

unacceptable, the FAA will consider 

further rulemaking to mandate 

assessments. 

This research may also assist in 

refining means of compliance with 

§ 25.571, at Amendment 25–96 or later, 

for repairs, alterations, and 

modifications. For airplanes certified to 

Amendment 25–96 or later, persons 

who repair or alter the airplane must 

address WFD. This has typically been 

done by showing the repair or alteration 

to be adequate up to the airplane’s 

design service goal. With adoption of 

this final rule, repairs, alterations, and 

modifications to airplanes designed in 

the future will have to be shown to be 

free from WFD up to the airplane’s LOV. 

4. Rely on the Changed Product Rule 

Northwest Airlines stated that it 

supports the FAA in removing WFD 

requirements for most repairs, 

alterations, and modifications, but 

requested that references to future 

alterations be removed from the final 

rule and addressed by the Changed 

Product Rule, 14 CFR 21.101. The 

Changed Product Rule requires that 

significant changes to type-certificated 

products comply with the latest 

amendments of the airworthiness 

standards unless one of the stated 

exceptions applies. In support of its 

position, Northwest Airlines cited 

concerns published by the AAWG about 

industry not having the resources or 

sufficient FAA guidance to accomplish 

WFD analysis for the expected 

quantities of supplemental type 

certificate alterations. 

Similarly, ATA stated that in view of 

their coverage under the Changed 

Product Rule, the FAA should exclude 

future supplemental type certificate 

applications from the applicability of 

this rule. Northwest Airlines and ATA 

requested that the FAA use the Changed 

Product Rule to regulate which future 

alterations would need to be evaluated 

for WFD. 

The Changed Product Rule would 

require applicants for future alterations 

and modifications to include the latest 


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amendment of part 25 for § 25.571 in the 

certification basis for the proposed 

alteration or modification if the change 

is considered significant. For the 

purposes of today’s rule, applicants 

would use the examples of significant 

changes identified in AC 21.101–1. For 

transport category airplanes, that AC 

may be used as a starting point for 

determining whether alterations or 

modifications are significant and must 

be evaluated to the latest amendment of 

§ 25.571. Examples of significant 

changes from AC 21.101–1 that would 

be required to be assessed for WFD 

include passenger-to-cargo conversions, 

gross weight increases, and cabin 

pressure increases. We have revised AC 

25.571–1X to provide additional 

guidance for identifying whether a 

change, or structure affected by the 

change, requires an assessment for 

WFD. Affected structure can be new 

structure installed by the change or 

existing structure modified by a change. 

Structure may be affected if it is 

physically changed or if there is a 

change or redistribution of internal 

loads. The long-term result will be that 

a changed product will have a 

certification basis that provides a 

similar level of safety to that provided 

by the certification basis of a new type 

certificate for the same product. 

F. Compliance Times for Developing 

and Implementing LOVs 

For existing airplanes, this final rule 

uses a phased approach for establishing 

LOVs and divides the compliance dates 

for holders of design approvals and 

applicable airplane models into three 

groups. The NPRM proposed that design 

approval holders establish LOVs for all 

affected airplanes by one specific date. 

The proposed rule did not account for 

the age of airplanes within a model. 

For this final rule, the compliance 

dates for the different airplane groups 

are identified based on their 

certification basis relative to § 25.571 

and are as follows: 

• Group I: Pre-Amendment 25–45 

airplanes (those with a certification 

basis dating before 1978). The Boeing 

727 and the Airbus A300 are examples 

of pre-Amendment 25–45 airplanes. 

• Group II: Amendment 25–45 up to 

but not including Amendment 25–96 

airplanes (those with a certification 

basis dating from 1978 to 1998). This 

group of airplanes would include the 

Boeing 757 and 767 and the Airbus 

A318. 

• Group III: Amendment 25–96 and 

later airplanes (those with a certification 

basis dating from 1998 to the present). 

The Airbus A380 and the Embraer ERJ 

170 and 190 are among the airplanes 

that have this certification basis. 

Table 1 in § 26.21 indicates the 

compliance times for these various 

groups of airplanes. They are 18, 48, and 

60 months, respectively. These 

compliance times apply to all existing 

versions of these airplane models. 

For airplane models for which a type 

certificate is approved as of the effective 

date, but which are not specifically 

named in Table 1 of § 26.21, an LOV 

must be established within 60 months 

after the effective date of the rule. In 

Table 1 of § 26.21, those airplanes 

would fall under the category of ‘‘All 

Other Airplane Models Listed on a Type 

Certificate as of January 14, 2011.’’ 

For type certificate or amended type 

certificate approvals that are pending as 

of this final rule’s effective date, and for 

future amendments to existing or 

pending type certificates, this final rule 

requires the applicants to establish an 

LOV by the latest of the following dates: 

• Within 60 months after the effective 

date of the rule, 

• The date a certificate is issued, or 

• The date specified in the plan 

approved under § 25.571(b) indicating 

when the full-scale fatigue testing and 

evaluation will be complete. 

This final rule requires operators to 

incorporate the Airworthiness 

Limitations section that includes the 

LOV into their maintenance program 

within 30, 60, or 72 months after the 

effective date for Groups I, II, and III, 

respectively. Table 1 in §§ 121.1115 and 

129.115 gives the compliance times for 

operators. 

This final rule also requires operators 

of affected airplanes whose applications 

for type certificates or amended type 

certificates are pending as of the 

effective date, or whose application for 

a type certificate or amended type 

certificate is made after the effective 

date of the rule, to incorporate the 

Airworthiness Limitations section that 

includes the LOV into their 

maintenance program at the latest of the 

following compliance times: 

• Within 72 months after the effective 

date of the rule, 

• Within 12 months after the LOV is 

approved, or 

• Before operating the airplane. 

In Table 1 of § 121.1115 and 

§ 129.115, those airplanes would fall 

under the category of ‘‘All Other 

Airplane Models (TCs and Amended 

TCs) not Listed in Table 2.’’ 

Amended or supplemental type 

certificates that change the maximum 

takeoff gross weight are grouped 

separately. Holders of amended type 

certificates or supplemental type 

certificates that increase the maximum 

takeoff gross weight to greater than 

75,000 pounds, regardless of whether 

such change was applied for before or 

after the effective date of the rule, must 

comply within 18 months after the 

effective date of the rule. Applicants for 

this type of design change approval 

whose applications are either pending 

as of the effective date of this final rule 

or submitted after the effective date 

must comply by the latest of the 

following dates: 

• Within 18 months after the effective 

date of the rule, 

• The date the approval is issued, or 

• The date specified in the plan 

approved under § 25.571(b) indicating 

when the full-scale fatigue testing and 

evaluation will be complete. 

Applicants for amended type 

certificates or supplemental type 

certificates applied for after the effective 

date of the rule that decrease the 

maximum takeoff gross weight to 75,000 

pounds or less must also comply by the 

latest of the following dates: 

• Within 18 months after the effective 

date of the rule, 

• The date the certificate is issued, or 

• The date specified in the plan 

approved under § 25.571(b) indicating 

when the full-scale fatigue testing and 

evaluation will be complete. 

This final rule requires operators of 

airplanes whose maximum takeoff gross 

weight was decreased to 75,000 pounds 

or below after the effective date of the 

rule or increased to greater than 75,000 

pounds at any time by an amended type 

certificate or supplemental type 

certificate to incorporate the 

Airworthiness Limitations section that 

includes the LOV into their 

maintenance program by the latest of 

the following compliance times: 

• Within 30 months after the effective 

date of the rule, 

• Within 12 months after the LOV is 

approved, or 

• Before operating the airplane. 

Those airplanes would fall under the 

category of ‘‘Maximum Takeoff Gross 

Weight Changes’’ in Table 1 of 

§ 121.1115 and § 129.115. 

Under 14 CFR 91.403(c), no person 

may operate an airplane unless that 

person is in compliance with applicable 

airworthiness limitations. By requiring 

operators to incorporate the 

Airworthiness Limitations Section 

containing the LOV into the 

maintenance program, this final rule 

makes those LOVs applicable to the 

affected airplanes, and § 91.403(c) 

requires operators to comply with them. 

Operators of airplanes whose type 

certificate was pending approval as of 

the effective date of the rule will be 

required to include one of the following 


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25Aviation Rulemaking Advisory Committee; 

Transport Airplane and Engine Issues—New Task, 

dated April 11, 2007. 

26A Structures Task Group is a model-specific 

group that consists of type certificate holders and 

operators responsible for the development of aging 

airplane model-specific programs. It also includes 

regulatory authorities which approve and monitor 

those programs. 

airworthiness limitations in their 

maintenance program: 

• The LOV that has been specified in 

the Airworthiness Limitations section of 

the Instructions for Continued 

Airworthiness; or 

• If the LOV has not yet been 

established, a number equal to 1⁄2 the 

number of cycles accumulated on the 

fatigue test article if a type certificate is 

issued prior to completion of full-scale 

fatigue testing. 

Comments received during the NPRM 

comment period were responding to the 

one specific compliance date published 

in the NPRM. Comments received 

during the comment period for the 

Technical Document, which described 

changes that had occurred to the rule 

since it had been proposed in the 

NPRM, were in response to the phased 

compliance dates published in the 

Technical Document, which are the 

dates cited in today’s rule. 

1. NPRM Compliance Date 

Commenters—including industry 

representatives on the AAWG, Cessna, 

Continental Airlines, Embraer, AWAS, 

the CAA, American Airlines, Boeing, 

Airbus, and FedEx—objected to the 

proposed compliance date of December 

18, 2007, for both technical and 

practical reasons. Several commenters 

stated that hard compliance dates and 

an expected final rule issuance in 

December 2006 would leave design 

approval holders with less than 12 

months to comply with the subpart I 

requirements (now part 26). These 

commenters requested that the FAA 

revise the compliance dates to represent 

a number of months after the effective 

date of the rule rather than a hard date. 

This approach would prevent the FAA’s 

schedule for issuing the final rule from 

affecting compliance by design approval 

holders. 

We have revised the compliance dates 

in this final rule to specify that persons 

must comply either by a date 

determined as a specified number of 

months after the effective date of the 

final rule or (for applicants) by the date 

of approval of the related certificate. 

2. When to Set LOVs for Existing 

Airplanes 

Industry representatives on the 

AAWG, Boeing, Continental Airlines, 

Northwest Airlines, ATA, Lynden Air 

Cargo, and FedEx stated that there 

should be a phased approach to setting 

LOVs, with the oldest airplane models 

being addressed first. The industry 

representatives on the AAWG suggested 

that existing airplane models subject to 

the rule be divided into two groups: (1) 

Pre-Amendment 25–45 airplanes and (2) 

airplanes certified to Amendment 25–45 

or later. The commenters stated that 

performing WFD evaluations on 

airplane models before the high-time 

airplane reaches its design service goal, 

as proposed in § 25.1807 (now § 26.21) 

and as specified in the Technical 

Document, would not significantly 

increase operational safety. This is 

because WFD is typically not a concern 

until later in an airplane’s operational 

life. As discussed earlier, these 

commenters objected to the proposed 

compliance date of December 18, 2007. 

Commenters also objected to the 

compliance times identified in the 

Technical Document—that is, 18 

months for pre-Amendment 25–45 

airplanes, 48 months for Amendment 

25–45 up to but not including 

Amendment 25–96 airplanes, and 60 

months for Amendment 25–96 

airplanes. 

Boeing said that the final rule should 

provide the greatest amount of time for 

design approval holders to develop 

LOVs, so that LOVs provide the greatest 

flexibility for the fleet. Several 

commenters argued that requiring 

compliance prior to or concurrent with 

the Aging Airplane Safety Rule (Damage 

Tolerance Data Rule) would not be 

practical because of limited industry 

and FAA resources. In addition, Boeing 

and Northwest Airlines argued that 

establishing an LOV for an airplane 

model before significant service 

experience had been accumulated 

would result in an erroneous LOV. 

We agree that it makes sense to have 

compliance dates for establishing LOVs 

for existing airplanes based on the 

relative safety risk (i.e., addressing the 

oldest airplanes first) and on available 

resources. However, the agency does not 

agree that ‘‘early’’ establishment of an 

LOV will result in an ‘‘erroneous’’ LOV. 

Setting an LOV without benefit of 

significant service experience might 

result in an LOV that sets the limit at 

a lower number of flight hours or flight 

cycles than one that benefits from 

significant service experience, but it 

would be incorrect to characterize it as 

‘‘erroneous.’’ This is because the LOV is 

a function of the fatigue knowledge base 

available at the time it is established. 

a. Pre-Amendment 25–45 Airplanes 

Industry representatives on the 

AAWG, Boeing, Continental Airlines, 

Northwest Airlines, ATA, and FedEx 

pointed out that the first group of 

airplanes is collectively at the highest 

risk because of cumulative time in 

service and the limited fatigue test data 

available for these models. They 

recommended that the compliance date 

for the first group of airplanes should be 

by a certain date after the effective date 

of the rule. The AAWG’s final report 25

recommends that LOVs be established 

for the first group of airplanes by June 

2009, or 18 months prior to the 

operator’s compliance date for the final 

rule, whichever occurs later. This would 

also provide sufficient time for 

Structures Task Groups 26 including 

operators of affected airplanes, to 

participate in establishing the LOVs. A 

later Boeing comment, however, 

requested that the compliance dates for 

those airplanes be 36 months, instead of 

18 months (as stated in the technical 

document), from the effective date of the 

rule. Boeing stated that this additional 

time would allow them to have the FAA 

review and accept the Boeing 

proprietary LOV methodology, prepare 

LOV fleet proposals, and coordinate 

them within Boeing and with operators 

before submitting them to the FAA for 

review and approval. 

The FAA agrees that pre-Amendment 

25–45 airplanes should be addressed 

first because they are among the oldest 

airplanes and at the highest risk for 

developing WFD. In fact, most high-time 

pre-Amendment 25–45 airplanes have 

exceeded their design service goals. 

While the FAA understands that LOVs 

have been developed for a number of 

affected airplanes, the agency also 

understands that not all design approval 

holders have begun or completed this 

activity on all affected models. The FAA 

recognizes the benefits of allowing 

Structures Task Groups to participate in 

setting LOVs. Therefore, the FAA has 

determined that the compliance period 

for the oldest affected airplanes should 

be increased to 18 months to allow 

sufficient time for design approval 

holders to show compliance with 

today’s rule. This increases by six 

months the amount of time design 

approval holders have to comply over 

what was anticipated in the NPRM. The 

2007 AAWG Task 3 Report further 

supports the compliance date of 18 

months. In its report, the AAWG stated 

that most of the work for the preAmendment 25–45 airplanes has 

already been completed. As a result, we 

do not concur with the commenter that 

36 months is necessary to establish 

LOVs. 


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27Under § 21.17, these applicants are subject to 

§ 25.571 at Amendment 25–96. In addition to this 

certification basis, they are subject to the 

requirements of this final rule. 

b. Airplanes Certified to Amendment 

25–45 or Later 

For the second group of airplanes 

(certified to Amendment 25–45 or later), 

industry representatives on the AAWG, 

Boeing, Continental Airlines, Northwest 

Airlines, ATA, and FedEx 

recommended setting a compliance date 

for design approval holders to establish 

LOVs that are tied to both the design 

service goal and the cumulative time on 

the high-time airplanes of that model. 

Specifically, the industry 

representatives on the AAWG proposed 

that within 180 days of the effective 

date of the rule, the type certificate 

holders provide design service goals for 

all affected airplane models to the FAA 

for approval. Once approved, these 

design service goals would be placed in 

an appropriate certification document. 

Other commenters—including Cessna, 

Continental Airlines, Embraer, AWAS, 

the CAA, American Airlines, Boeing, 

Airbus, and FedEx—agreed with 

industry representatives on the AAWG 

that the compliance date for setting 

LOVs should take into account both the 

design service goal and the cumulative 

time on the high-time airplanes of that 

model. 

The industry representatives on the 

AAWG proposed that the design 

approval holder prepare a compliance 

plan with a binding schedule for a WFD 

evaluation when the high-time airplane 

reaches a point five years from its 

design service goal. The AAWG 

industry representatives suggested that a 

means of determining this time should 

be included in AC 120–YY. FedEx and 

Lynden Air Cargo suggested that the 

FAA use the design service goals that 

are being developed under the Damage 

Tolerance Data Rule to establish 

compliance dates for establishing LOVs 

and associated WFD maintenance 

actions. The commenters said that if no 

design service goal or design service 

objective exists, the LOV should be 

established when the high-time airplane 

of a particular model reaches 20 years 

of age. 

In contrast, United Parcel Service and 

Technical Data Analysis, Inc. supported 

establishing LOVs for all affected 

airplane models as soon as possible, 

because of the uncertainty associated 

with estimating future operating costs 

and the length of time that airplanes can 

be operated. 

The WFD risk for these newer 

airplane models is lower than for the 

pre-Amendment 25–45 airplanes 

because these airplanes are generally 

younger and have been certified to 

damage tolerance requirements. 

Therefore, the FAA agrees with the 

industry representatives on the AAWG 

and other commenters that the 

compliance times can be longer for 

these airplanes. On the other hand, the 

proposal of the AAWG industry 

representatives would add a level of 

complexity and uncertainty to 

determining compliance times that the 

FAA considers unnecessary and 

inappropriate and that would make 

operators’ long-term planning difficult. 

Therefore, as discussed earlier, to 

accommodate the need for a longer 

compliance time for these airplanes, this 

final rule creates three groups of 

airplane models for determining 

compliance dates. 

• Group I—Pre-Amendment 25–45 

(1978) airplanes. 

• Group II—Airplanes certified to the 

requirements of § 25.571, Amendment 

25–45, up to but not including 

Amendment 25–96 (1998). 

• Group III—Airplanes certified to 

requirements of § 25.571, Amendment 

25–96 or later. 

Group II airplane models were all 

subjected to full-scale fatigue test 

programs. In addition, all the models in 

this group have been in service for a 

period of time. There should, therefore, 

be a reasonable knowledge base readily 

available on which to base an LOV. 

Today’s rule requires establishment of 

an LOV for all these models within 48 

months of the effective date of the rule, 

as indicated in Table 1 of § 26.21. This 

would allow design approval holders to 

schedule development of these LOVs 

after the more urgent development of 

LOVs for pre-Amendment 25–45 

airplanes, so project schedules would 

not conflict. At the same time, this 

compliance time would ensure that 

LOVs are established long before the 

high-time airplanes of these models 

would reach their anticipated LOVs. 

Design approval holders of those 

models in Group III have had to 

demonstrate or will have to demonstrate 

with sufficient full-scale test evidence 

that WFD will not occur within the 

design service goal of the airplane. 

Therefore, the design service goal would 

be a valid LOV that is based on the 

knowledge base considered. However, 

because these airplanes have not 

accumulated much time in service, 

there is less urgency in establishing an 

LOV. As a result, the final rule provides 

60 months after the effective date of the 

rule to establish an LOV for these 

models. (See Table 1 of § 26.21.) This 

provides time to re-evaluate the fatigue 

data and to establish an LOV which may 

exceed the design service goal. 

Extending the compliance date for 

Group III airplanes beyond the 

compliance date for Group II airplanes 

reduces the resource concerns about 

developing LOVs for multiple airplane 

models at the same time. 

Table 1 of § 26.21 includes a 

compliance date for airplanes that do 

not appear in the table but may have 

had a type certificate approved by the 

effective date. These have a compliance 

period of 60 months. Some type 

certificates are pending and may be 

approved shortly. This last row of the 

table is meant to capture any additional 

airplanes that fit the applicability 

criteria of § 26.21(a). 

Table 1 of § 26.21 is used to call out 

existing airplanes and assign 

compliance dates. Holders of type 

certificates for these models must 

comply with § 26.21(c)(1). The 

remainder of § 26.21(c) specifies 

additional people who must comply. 

Under today’s rule, the compliance 

times specified in § 26.21(c) for when 

applicants must establish an LOV 

include the date specified in the 

applicant’s plan for completion of the 

full-scale fatigue testing and analyses of 

the testing to demonstrate compliance 

with § 25.571(b).27 All applicants who 

must comply with § 26.21 may use this 

date as one option for compliance. 

Applicants who have the same 

compliance times and the option to use 

the date specified in the § 25.571(b) plan 

are: 

• Applicants for type certificates for 

which the application is pending as of 

the effective date. 

• Applicants for amendments to type 

certificates (with the exception of those 

that change the weight of the airplane). 

All of these applicants are required to 

establish LOVs at the latest of the 

following dates: 

• The date the type certificate or 

amended type certificate is issued, 

• Within 60 months after the effective 

date of the rule, or 

• The date specified in the plan 

approved under § 25.571(b) indicating 

when the full-scale fatigue testing and 

evaluation will be complete. 

Among these applicants, WFD is of 

less immediate concern because their 

high-time airplanes will have 

accumulated relatively few flight cycles 

or flight hours by the compliance date. 

Establishing LOVs early in the service 

life of these airplanes will assist 

operators in their long-term planning. 

This approach also serves as a transition 

to § 25.571 as amended by this final 

rule, which requires establishing LOVs 

as part of initial type certification. 


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Maximum takeoff gross weight 

changes to an airplane are treated 

separately in this rule. Holders of either 

supplemental type certificates or 

amendments to type certificates that 

increase maximum takeoff gross weights 

from 75,000 pounds or less to greater 

than 75,000 pounds must comply no 

later than 18 months after the effective 

date. 

Applicants for supplemental type 

certificates or amended type certificates 

that increase the maximum takeoff gross 

weight to greater than 75,000 pounds 

must comply by the latest of the 

following: 

• Within 18 months after the effective 

date of the rule, 

• The date the certificate is issued, or 

• The date specified in the plan 

approved under § 25.571(b) indicating 

when the full-scale fatigue testing and 

evaluation will be complete. 

The option of 18 months after the 

effective date as a compliance choice for 

this group represents a six-month 

increase in the time to comply over 

what was originally proposed. We based 

these compliance dates on the length of 

time given for design approval holders 

of Group I airplanes to comply. 

The NPRM did not specify a 

compliance time for applicants for 

design change approvals that, after the 

effective date of the rule, decrease the 

maximum takeoff gross weight to 75,000 

pounds or less. This is because the 

applicability provision in the NPRM 

included airplanes with maximum 

takeoff gross weights exceeding 75,000 

pounds, as approved during the original 

type certification. By referencing the 

capacity resulting from original type 

certification, the NPRM required 

applicants to establish LOVs for design 

change approvals that, after the effective 

date of the rule, decrease the maximum 

takeoff gross weight to 75,000 pounds or 

less. Although not explicitly stated in 

the NPRM, the LOV for those airplanes 

is required to be established by the 

compliance date for the original type 

certification or, in the case of 

applicants, by the date the approval of 

the design change has been issued. 

Because the NPRM was not clear about 

when those applicants must comply, the 

FAA has revised today’s rule. 

Applicants for design change approvals 

that decrease the maximum takeoff gross 

weight to 75,000 pounds or less after the 

effective date of the rule must comply 

within 18 months after the effective date 

of the rule or by the date the certificate 

is issued or by the date specified in the 

plan approved under § 25.571(b), 

whichever occurs latest. 

The FAA has also revised the 

compliance times to require those 

applicants who would decrease the 

gross weight of their airplanes after the 

effective date of the rule to submit a 

compliance plan within 90 days after 

the date of application. 

3. Varying Implementation Strategies 

APA suggested a way to address 

concerns about the time needed to 

develop an LOV. The commenter stated 

that the initial LOVs under 

consideration, as defined in the 

Technical Document, appear to be 

extremely liberal and based on limited 

data and minimal analysis. APA 

assumed that manufacturers would need 

more time to develop their analysis 

procedures, and said that a better 

approach for establishing the initial 

LOV would be to increase the design 

service goal by 10% to 15% and 

mandate inspections of high-time 

airplanes that are over their design 

service goal. APA based its suggestion 

on an assumption that the design 

service goals were based on hard test 

and engineering data. The commenter 

suggested halving the interval between 

maintenance checks for airplanes over 

their design service goal. Then, the 

commenter suggested, results of these 

inspections could be given to the 

manufacturer for use in substantiating 

the engineering WFD analysis. This data 

could be used to validate future 

incremental LOV increases. 

Although this commenter maintained 

that design service goals are based on 

hard test and engineering data, that has 

not always been the criteria by which 

design service goals have been set. 

Amendment 25–96 to § 25.571 

introduced requirements that applicants 

show freedom from WFD up to the 

design service goal. Prior to Amendment 

25–96, however, there was no 

requirement for setting a design 

approval holder’s design service goal or 

for validating it. Design approval 

holders have always used engineering 

data to substantiate their designs. Most 

design approval holders set design 

service goals for their airplanes, even 

though they were not required to do so. 

But since there were no requirements 

prior to Amendment 25–96 about what 

criteria must be used to set the design 

service goal, they have often been set for 

purposes driven more by sales and 

marketing than by engineering data. 

Some design approval holders have 

stated that LOVs may be established at 

a point anywhere from 33% to 180% 

higher than the airplane’s design service 

goal for certain models. This is because, 

for those design approval holders, there 

is a large body of in-service data to 

support these higher LOVs. Other 

design approval holders have taken an 

approach similar to APA’s 

recommendation, in that they have been 

incrementally increasing their airplane 

model’s LOV as the data supports it. 

Today’s rule allows for an 

implementation strategy that provides 

flexibility to design approval holders in 

determining the timing of service 

information development (with FAA 

approval), while providing operators 

with certainty regarding the LOV 

applicable to their airplanes. However, 

no matter how the design approval 

holder chooses to manage LOV 

development, those LOVs must still be 

substantiated by engineering data. 

4. FAA Review and Approval Time 

Industry representatives on the 

AAWG, Boeing, Airbus, and CAA 

requested that the rule include required 

time periods for FAA review and 

approval activities. These commenters 

noted that the rules do not currently 

limit the amount of time the FAA will 

take to review and approve documents 

and that this will negatively affect their 

compliance time. Several commenters 

also noted that the amount of time the 

FAA will take to review and approve 

design approval holders’ LOVs could 

reduce operator compliance time 

significantly. 

We are not including required time 

periods for FAA review and approval of 

the required compliance activities. 

Instead, expectations for FAA personnel 

have been defined in FAA Order 

8110.104, which directs the Aircraft 

Certification and Flight Standards 

Services in their roles and 

responsibilities for implementing these 

initiatives. The order includes expected 

times (6 weeks) for reviewing and 

approving design approval holder 

compliance plans, plans to correct 

deficiencies, and draft and final 

compliance data and documents. To 

facilitate implementation, the FAA will 

train affected personnel in their roles 

and responsibilities and provide indepth familiarization with requirements 

of the regulations and associated 

guidance. Ultimately, however, the 

timing of FAA approvals will be 

determined by the quality of the design 

approval holder submissions and their 

responsiveness to issues raised by the 

FAA. 

We have structured the requirements 

of the design approval holder rule and 

developed complementary guidance to 

facilitate timely review and approval of 

design approval holder submittals (such 

as compliance plans). An increase in 

operator compliance time would help 

ensure that operators are not affected by 

the FAA review and approval process. 

We have revised the WFD compliance 


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date for operators from 6 months to 12 

months after the relevant design 

approval holder compliance date. This 

date is measured after the effective date 

of the final rule. As previously noted, 

for Group I, II, and III airplanes, the 

operator compliance dates are 30, 60, 

and 72 months, respectively, after the 

effective date of the rule. 

G. LOVs for Future Airplanes: § 25.571, 

Appendix H, and Operational Rules 

This final rule revises § 25.571 to 

require that— 

• An LOV be established that 

corresponds to the time during which it 

is demonstrated that WFD will not 

occur in the airplane structure, and 

• The LOV be included in the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness required by § 25.1529. 

Except for the change in terminology 

from initial operational limit to LOV, 

these revisions to § 25.571 are as 

proposed in the NPRM. 

For operators of airplanes type 

certificated in the future, this final rule 

relies on existing operational rules to 

require operators to include the 

airplane’s LOV, which is established 

under § 25.571 of today’s rule, into their 

maintenance/inspection programs. This 

requirement is the same as that which 

was proposed in the NPRM. 

1. Opposition to Changes to § 25.571 

Industry representatives on the 

AAWG and Airbus commented that no 

change is needed to § 25.571 because 

airplanes certified to Amendment 25–96 

must be free from WFD until they reach 

the design service goal, and the design 

service goal must be declared in the 

appropriate certification document. 

We recognize that § 25.571 at 

Amendment 25–96 requires full-scale 

fatigue test evidence to demonstrate 

freedom from WFD up to the design 

service goal. However, the current 

regulations do not require that the 

Airworthiness Limitations section 

include the design service goal as an 

airworthiness limitation, so operators 

would be permitted to operate airplanes 

beyond this goal indefinitely. Therefore, 

the FAA finds it necessary to revise 

§ 25.571, as proposed, to require that 

full-scale fatigue test evidence be used 

to demonstrate freedom from WFD up to 

the LOV and that the LOV be included 

in the Airworthiness Limitations 

section. These changes are consistent 

with recommendations made in 2003 by 

the General Structures Harmonization 

Working Group, a separate working 

group within ARAC. 

2. Change to Appendix H 

Under § 25.571, the FAA may issue a 

type certificate for an airplane model 

prior to completion of full-scale fatigue 

testing. As stated in the NPRM, the FAA 

did not propose to change this provision 

because the FAA intends that operators 

be able to operate these airplanes while 

the design approval holder is 

performing fatigue testing. Today’s rule 

retains the requirement of § 25.571 

that—if a type certificate is issued prior 

to completion of full-scale fatigue 

testing—the Airworthiness Limitations 

section must include a number equal to 

c the number of cycles accumulated on 

the fatigue test article. As additional 

cycles on the test article are 

accumulated, the number may be 

adjusted accordingly. This number is an 

airworthiness limitation, and no 

airplane may be operated beyond it 

until the fatigue testing is completed 

and the LOV is established. 

For consistency however, the FAA 

has revised paragraph (a)(4) of H25.4 to 

part 25 (Appendix H) to include a 

reference to the limitation that an 

airplane may accumulate a number of 

cycles not greater than 1⁄2 the number of 

cycles accumulated on the fatigue test 

article until such testing is completed. 

3. When to Set LOVs for Future 

Airplanes 

Industry representatives on the 

AAWG, Boeing, and American Airlines 

commented that design approval 

holders should not be required to 

establish an LOV for a future airplane 

until the high-time airplane approaches 

its design service goal. United Parcel 

Service, on the other hand, 

recommended that the initial LOV be 

established during the initial 

certification process, and before the first 

airplane enters service. The ATA 

recommended that LOVs should be 

estimated at the time of airplane 

certification but should be reassessed 

when the high-time airplane approaches 

75% of the estimate. 

The LOV is a function of the fatigue 

knowledge base available at the time it 

is established. There should be 

sufficient data to establish an LOV for 

a new airplane model being certificated 

once full-scale fatigue test evidence is 

completed and assessed, normally 

several years after the airplane enters 

service. We agree that an LOV 

established for a new airplane model 

could be reassessed later when service 

information could be used with other 

data necessary to extend the LOV. 

Eliminating the requirement to address 

repairs, alterations, and modifications 

will simplify the process for extending 

the LOV. 

The FAA does not agree that 

establishment of an LOV for a future 

airplane model should wait until the 

high-time airplane approaches its design 

service goal. As discussed previously, 

establishing design approval holder 

compliance dates that are a function of 

when high-time airplanes reach their 

design service goal would introduce a 

level of complexity and uncertainty to 

the requirements of the operational 

rules that is unnecessary and 

inappropriate. 

One manufacturer is already 

employing the concept of establishing 

LOVs based on the fatigue knowledge 

base available through the certification 

process. Airbus has already included an 

LOV in the applicable Airworthiness 

Limitations section approved by EASA 

for all of its models with the exception 

of the A340. 

4. Operational Rules 

For airplanes whose type certificate 

application is made after the effective 

date of this final rule, LOVs must be 

established by the date the certificate is 

issued or the date specified in the plan 

approved under § 25.571(b). The LOV 

will be included in the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness and will 

apply regardless of how or by whom the 

airplane is operated. 

As discussed above, the FAA may 

issue a type certificate for an airplane 

model before full-scale fatigue testing 

has been completed. In that case, the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness must include a number 

equal to 1⁄2 the number of cycles 

accumulated on the fatigue test article. 

Under § 91.403(c), operators may not 

operate these airplanes beyond this 

number of cycles. Once the fatigue 

testing is completed and the LOV is 

established and approved, operators 

may revise this airworthiness limitation 

to include the LOV. This LOV will be 

higher than the airworthiness limitation 

specifying 1⁄2 the number of fatigue test 

article cycles. 

H. How to Set LOVs 

Section 26.21(b) of this final rule 

requires design approval holders to 

establish an LOV of the engineering data 

that supports the structural maintenance 

program. This LOV corresponds to the 

period of time, stated as a number of 

total accumulated flight cycles or flight 

hours, or both, during which the design 

approval holder is able to demonstrate 

that WFD will not occur in the airplane. 

This demonstration must include an 


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28AAWG, Widespread Fatigue Damage Bridge 

Tasking Report, July 23, 2003. 

29Mandatory modification, corrosion prevention 

and control, supplemental structural inspection, 

and repair assessment. 

evaluation of airplane structural 

configurations and be supported by test 

evidence and analysis. If available, 

service experience, or service 

experience and teardown inspection 

results, may be added to the test 

evidence and analysis to provide 

additional substantiation. The service 

experience and teardown inspections 

must be of high-time airplanes of similar 

structural design, accounting for 

differences in operating conditions and 

procedures. 

The NPRM proposed in § 25.1807(b) 

[adopted here as § 26.21(b)] that holders 

of design approvals for existing 

airplanes subject to the rule be required 

to evaluate airplane structural 

configurations to determine when WFD 

was likely to occur for structure 

susceptible to multiple site damage or 

multiple element damage. The results of 

the evaluation were to be used to 

support establishment of an initial 

operational limit (now the LOV.) 

The Boeing Company and industry 

representatives on the AAWG 

commented that proposed § 25.1807 

would require an ‘‘evaluation’’ that is 

not adequately defined and that there 

are no objective criteria for 

establishment of an LOV. These 

deficiencies could result in 

establishment of an LOV based solely on 

analyses of structure susceptible to 

multiple site damage and multiple 

element damage, without consideration 

of more relevant and reliable data, such 

as test evidence and service experience. 

These commenters concluded that, in 

these circumstances, airplanes could be 

operated well past the point to which 

the engineering data supports safe 

operation. 

The commenters recommended that 

the required evaluation explicitly 

include the following tasks, which are 

described in the AAWG’s 2003 report 28

as necessary to establish or extend an 

LOV. 

1. Ensure that the basics of the Aging 

Aircraft Program are in existence. 

2. Collect data necessary to extend 

fatigue test evidence. 

3. Perform analysis of the structure for 

multiple site damage and multiple 

element damage. 

4. Create and update maintenance 

documents to include maintenance 

actions and modifications for those 

areas where it has been predicted that 

multiple site damage and multiple 

element damage will occur before the 

proposed LOV. 

In addition, industry representatives 

on the AAWG and Boeing 

recommended that the rule explicitly 

use the term ‘‘fatigue test evidence’’ to 

refer to the collective body of 

information that should be considered 

in establishing an LOV. The FAA agrees 

that the first task, having basics of the 

four elements of the Aging Aircraft 

Program in place,29 is an important 

element for continued safe operation out 

to LOV. However, as discussed in the 

NPRM, this final rule does not include 

requirements related to those initiatives 

because they are already mandated by 

airworthiness directives, operational 

rules, and airworthiness limitations. 

The FAA considers that tasks 2 and 3 

are implicit in the text of the proposed 

rule but agrees that proposed § 25.1807 

could be misinterpreted and result in 

too much reliance on results of analysis 

to preclude WFD up to the LOV. This 

was not our intent. In fact, as discussed 

in the NPRM, our intent was consistent 

with the AAWG’s recommendations 

regarding WFD. 

In response to these commenters, the 

FAA has revised the proposed rule to 

clarify how the LOV is to be established. 

This final rule specifies that—for an 

LOV to be acceptable—the supporting 

evaluation must demonstrate that the 

fatigue characteristics and any specified 

maintenance actions for the airplane are 

sufficient to prevent WFD from 

occurring before the LOV. 

The required demonstration typically 

involves an evaluation of the airplane 

structure to determine its susceptibility 

to WFD and, if the structure is 

susceptible, an evaluation indicating 

that WFD will not occur before the 

proposed LOV. The evaluation must be 

supported by test evidence and analysis. 

The design approval holder may 

augment the test evidence and analysis 

with any available service experience, 

or service experience and teardown 

inspection results of high-time 

airplanes. Service experience and 

teardown inspection results must be of 

airplanes of similar structural design 

and must account for differences in 

operating conditions and procedures. 

After seeing these changes to the rule as 

they were described in the Technical 

Document, Boeing stated that it 

supports the FAA’s adoption of an 

airplane-level assessment of fatigue test 

evidence as the basis for both the 

determination and extension of LOV. 

The FAA is using the term ‘‘test 

evidence’’ to align with the rule text of 

§ 25.571 relative to WFD. Therefore, in 

the context of this final rule, test 

evidence is data derived from full-scale 

fatigue testing, which may be of the 

complete airplane, or of separate major 

sections of the airplane, or a 

combination of the two. The test 

evidence would be used to support the 

proposed LOV for an airplane model. 

The amount of test evidence required to 

show compliance would depend on 

where a design approval holder 

proposes to set an LOV and what data 

(such as test evidence or service 

experience) already exist. 

For a new airplane model that is 

pending approval, there should be test 

evidence to address all WFD-susceptible 

structural areas of an airplane. The test 

duration should be at least two times 

the proposed LOV. The test evidence 

may be from prior full-scale fatigue tests 

performed by the applicant or others on 

similar structure. For derivative models, 

the applicant should compare the 

derivative model to the tested model. To 

use the test evidence from the original 

certification project or previous 

derivatives, the applicant should show 

that the derivative model does not 

significantly change the basic structural 

design concept, aerodynamic contour, 

and internal load distribution. Advisory 

Circulars 120–YY and 25.571–1X 

further describe considerations for when 

existing test evidence could be used. 

For some older airplanes, fatigue test 

data may be limited to fuselage 

structure. This is because the 

pressurized fuselage has been 

considered to be the most fatiguecritical part of the airplane. The wing 

and empennage have typically been 

considered less critical and, as a result, 

relevant test data may not exist. 

However, for these same airplane 

models, significant service experience 

does exist. The FAA would accept a 

combination of test evidence and 

analysis as well as service experience as 

data to show compliance with this final 

rule. 

For example, in the case of one of the 

pre-Amendment 25–45 airplane models, 

significant numbers of airplanes both in 

service and in storage have accumulated 

flight cycles in excess of the design 

service goal. For this model, there is 

significant existing test evidence for the 

fuselage, but very little for the wing. In 

this case, the FAA expects that 

demonstrating freedom from WFD for 

the wing would be based primarily on 

service experience; for the fuselage, it 

would be based primarily on service 

experience and test evidence. Advisory 

Circular 120–YY further describes 

considerations for when service 

experience could be used to supplement 

existing fatigue testing that is limited to 

certain major components of the 

airplane, such as the fuselage. 


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The FAA has used the term ‘‘analysis’’ 

to include fatigue and damage tolerance 

analyses. Teardown inspections of inservice airplanes and fatigue test articles 

should be performed to the degree 

necessary to validate that the test 

evidence, analysis, and service 

experience are representative of the 

fatigue performance of the airplane out 

to the LOV. Design approval holders 

must explain in their certification plan 

how they intend to substantiate their 

proposed LOV. The FAA has revised AC 

120–YY to provide further guidance on 

the steps to take for establishing an 

LOV. 

As discussed in the NPRM, design 

approval holders are not required to 

identify and develop maintenance 

actions if they can show that such 

actions are not necessary to prevent 

WFD before the airplanes reach LOV. If 

they choose to establish LOVs that rely 

upon maintenance actions to prevent 

WFD before the LOV, they must identify 

those actions and, unless the necessary 

service information already exists, 

develop the service information in 

accordance with a binding schedule 

approved by the FAA. Those actions 

would then be mandated, not by today’s 

rule, but by future airworthiness 

directives. 

To be approved, the ‘‘binding 

schedule’’ for necessary maintenance 

actions must ensure that the service 

information is provided in a ‘‘timely 

manner.’’ In the NPRM, the FAA 

explained that the purpose of this 

requirement was to enable the FAA to 

issue the necessary airworthiness 

directives in time to allow operators to 

accomplish these actions during normal 

maintenance. The intent is to allow 

design approval holders the flexibility 

to focus their efforts on initially 

developing service information on those 

maintenance actions that must be 

accomplished first. At the same time, 

the FAA expects design approval 

holders to devote sufficient resources to 

these efforts so that: 

• The service information is available 

when the FAA needs it to initiate the 

airworthiness directive rulemaking 

process, including providing public 

notice and opportunity to comment; and 

• The resulting airworthiness 

directives will provide sufficient 

compliance times so that the required 

actions can be accomplished without 

disrupting operators’ normal 

maintenance schedules. 

Airbus stated that the analysis is the 

driver for substantiating LOVs and that 

test evidence supports the analysis. 

Analysis methods are used in 

combination with the engineering data 

to characterize WFD behavior to the 

degree necessary to determine if 

maintenance actions are required prior 

to the proposed LOV. As a result, test 

evidence and analysis are both required 

to demonstrate freedom from WFD. This 

is consistent with the existing 

requirements of § 25.571 at Amendment 

25–96. 

We agree that a design approval 

holder may not have both service 

experience and teardown inspection 

results available to use as part of its 

compliance data. We have modified the 

requirement so that a design approval 

holder may have either service 

experience or service experience and 

results of teardown inspections. The 

change is follows: 

‘‘This demonstration must include an 

evaluation of airplane structural 

configurations and be supported by test 

evidence and analysis at a minimum 

and, if available, service experience, or 

service experience and teardown 

inspection results, of high-time 

airplanes of similar structural design, 

accounting for differences in operating 

conditions and procedures.’’ 

I. How To Extend LOVs 

Proposed § 25.1811 provided that any 

person could apply to extend an 

operational limit, using a process 

similar to that for establishing the initial 

operational limit. The configuration to 

be evaluated would consist of not only 

all model variations and derivatives 

approved under the type certificate for 

which the extension is sought, but also 

all structural repairs, alterations, and 

modifications to those airplanes, 

whether mandated by airworthiness 

directive or not. 

Section 26.23(b) of this final rule 

(proposed as § 25.1811) contains 

requirements for obtaining approval of 

an extended LOV that corresponds to 

the period of time, stated as a number 

of total accumulated flight cycles or 

flight hours or both, beyond an existing 

LOV during which it is demonstrated 

that WFD will not occur in the airplane. 

This demonstration must include an 

evaluation of airplane structural 

configurations and be supported by test 

evidence and analysis at a minimum 

and, if available, service experience, or 

service experience and teardown 

inspection results of high-time airplanes 

of similar structural design, accounting 

for differences in operating conditions 

and procedures. Requirements for this 

section are the same as those for 

establishing an LOV. The FAA has 

removed the requirement to evaluate 

repairs, alterations, and modifications 

from § 26.23. 

1. Change the Procedure for Extending 

LOVs 

Industry representatives on the 

AAWG, ATA, Cessna, Airbus, United 

Parcel Service, FedEx, Boeing, and 

American Airlines stated that the means 

proposed in § 25.1811 for extending an 

operational limit is administratively 

difficult, impractical, and technically 

unachievable. The commenters 

expressed doubt that the proposed 

process could be realistically or 

uniformly accomplished because 

different operators will be involved in 

extending the LOV for the same airplane 

model. Furthermore, said the 

commenters, it is unlikely that any 

single operator has the information 

necessary to obtain an extended LOV. 

The cost, and uncertainty about the 

outcome of the evaluation, would make 

this process nearly impossible for an 

operator to attempt. 

The commenters added that extending 

an LOV would need to be done by 

addressing each individual airplane, 

identified by tail number, whereas the 

maintenance actions which support the 

initial LOV are based on statistics 

pertaining to behavior of the entire fleet 

of a particular model. Thus, the method 

of determining maintenance actions to 

preclude WFD out to the LOV is not 

valid for a single airplane. The AAWG 

industry representatives recommended 

that establishing an extended LOV and 

evaluating repairs, alterations, and 

modifications be a sequential process. 

The first step would be to establish the 

extended LOV. The second step would 

be for each design approval holder for 

a modification to evaluate its own 

design relative to the extended LOV and 

obtain a separate, independent approval 

for its design. The operator would 

continue to be responsible for 

assembling all maintenance 

requirements, depending on actual 

airplane configuration, and for obtaining 

approval of the maintenance program 

from the principal maintenance 

inspector. Such a process is similar to 

industry proposals for compliance with 

the Aging Airplane Safety Final Rule. 

Several commenters also remarked 

that the administrative process for 

obtaining an amended type certificate or 

supplemental type certificate will be 

extraordinarily difficult to manage 

because manufacturers, operators, and 

holders of supplemental type 

certificates do not necessarily have 

access to each other’s proprietary 

information. The existing business and 

legal agreements in place did not 

contemplate the high degree of data 

disclosure that will be required to 

develop WFD guidance material and 


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data needed for an amended type 

certificate or supplemental type 

certificate. Furthermore, many transport 

airplanes are converted to operate in 

different roles than those for which they 

were originally designed. Often 

operators cannot obtain support or 

design data from design approval 

holders because the latter have concerns 

about liability, are no longer in 

business, or are more motivated to sell 

new airplanes than to support old ones. 

Several commenters recommended 

that the FAA delete proposed § 25.1811 

and revise proposed § 25.1807 to allow 

extension of an LOV by a process 

approved by the Administrator. They 

base their recommendation on the fact 

that the technical requirements for 

establishing an LOV are no different 

from those for establishing an extended 

LOV. 

The FAA agrees that, given the 

extensive information required to 

develop guidelines for including a WFD 

evaluation of repairs, alterations, and 

modifications, the proposed 

requirements for extending the LOV 

needed to be changed. As discussed 

earlier, the FAA has removed those 

requirements. As a result, this final rule 

includes requirements for extending an 

LOV based on the original LOV airplane 

configuration plus all new structural 

modifications or replacements 

mandated by airworthiness directives. 

The FAA has revised requirements of 

§ 26.23(b) to be consistent with 

§ 26.21(b). As previously stated, if our 

research demonstrates that additional 

actions are needed to address risks for 

repairs, alterations, and modifications, 

the FAA will consider further 

rulemaking. 

The FAA does not agree with the 

suggestions to allow extension of an 

LOV using a process approved by the 

Administrator. In this final rule, 

requirements for extending an LOV are 

similar to those for establishing the first 

LOV. However, the design approval 

holder is not required to develop the 

data to support an extended LOV 

because such extensions are optional. 

The extended LOV and associated 

maintenance actions (inspections, 

modifications, or replacements) must be 

defined within the Airworthiness 

Limitations section for the airplane. 

This requirement is unchanged from the 

proposed requirements of § 25.1811(b) 

of the NPRM. As stated in the NPRM, 

the FAA intends to use airworthiness 

directives to mandate any maintenance 

actions necessary to reach the LOV 

established under § 26.21, so that 

operators will have an opportunity to 

comment on the proposed maintenance 

actions. It is not necessary to use this 

process for extensions of the LOV, 

however, because the extended LOV 

would include all maintenance actions 

at the time of approval. For these 

reasons, the FAA has kept requirements 

for extending an LOV separate from 

§ 26.21. The FAA has revised AC 120– 

YY to provide guidance on establishing 

an extended LOV. 

2. Evaluation of Repairs, Alterations, 

and Modifications for an LOV Extension 

EASA stated that certain existing 

repairs, alterations, and modifications 

should be evaluated for WFD when the 

LOV is being extended. EASA states that 

the risk of WFD increases for repairs, 

alterations, and modifications as 

airplanes age. 

As discussed elsewhere in this 

document, an extension should be based 

on the airplane’s structural 

configuration, just as the initial LOV is. 

Persons establishing extensions to LOVs 

may identify conditions or limitations 

in the Airworthiness Limitations section 

of the Instructions for Continued 

Airworthiness that apply to the 

extensions. For example, the LOV 

extension may only be valid for 

airplanes that operate at a certain cabin 

differential pressure or maximum 

takeoff gross weight. Operators may 

have to evaluate their airplanes and take 

certain actions prior to incorporating 

any extensions. AC 120–YY provides 

additional guidance on this. 

3. Alternate Means of Compliance 

(AMOCs) 

APA commented that operators 

should not be allowed alternate means 

of compliance (AMOCs) for the WFD 

rule because, it says, if the FAA allows 

AMOCs as it does with airworthiness 

directives, the ability to collect data and 

track compliance will be greatly 

complicated. Each operator, said the 

commenter, will comply in a manner 

with the least financial impact to its 

company. This may or may not be 

supported by the ongoing efforts of the 

original equipment manufacturers to 

develop analysis techniques and 

procedures. It will also add significant 

financial costs to the original equipment 

manufacturers and the FAA to support, 

track, and verify each AMOC. 

The initial LOV is established and 

approved under § 26.21 or § 25.571. Any 

extension to the initial LOV or any 

subsequent LOV is established and 

approved under § 26.23. The FAA does 

not issue AMOCs for these regulations. 

Any deviation from a rule is handled via 

the procedures contained in 14 CFR part 

11. 

Under § 26.21, any maintenance 

actions needed to support the initial 

LOV will be mandated by airworthiness 

directives, and compliance with those 

airworthiness directives and the ability 

to apply for an AMOC for those 

maintenance actions will not involve 

procedures that are any different from 

those used for airworthiness directives 

today. An AMOC for the maintenance 

actions for an initial LOV will not affect 

the LOV itself. 

Under § 26.23, however, any 

maintenance actions developed to 

support the extended LOV will be 

incorporated into the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness. The 

maintenance actions for extended LOVs 

will not be published in airworthiness 

directives. 

4. Extension Procedure Doesn’t Allow 

Public Comment 

ATA and Northwest Airlines stated 

that the proposed rule does not permit 

the public to comment on extensions to 

LOVs and the maintenance actions that 

support them. Extensions to LOVs 

mandated by airworthiness directive 

would allow the opportunity for public 

comments on extended LOVs. 

Although mandating LOV extensions 

by airworthiness directive would allow 

the public the opportunity to comment, 

the FAA does not agree with the 

suggestions to use airworthiness 

directives to allow extension of an LOV. 

This is for two reasons: 

• Approving an extended LOV isn’t 

rulemaking; it’s a finding of compliance 

with the applicable regulatory standard 

(i.e., freedom from WFD). 

• If the FAA doesn’t extend the LOV, 

or subsequent extensions of that LOV, 

there’s no unsafe condition justifying an 

airworthiness directive, because affected 

airplanes are grounded when they reach 

the LOV. 

The FAA has revised AC 120–YY to 

provide guidance on establishing an 

extended LOV. 

The AAWG recommended in its Task 

3 Report that design approval holders 

and operators work together in 

establishing LOVs and LOV extensions. 

Under today’s rule, the FAA expects 

that design approval holders and 

operators will work together when 

persons are seeking approval for 

extended LOVs. 

J. Applicability for Existing Airplanes 

The rule proposed in the NPRM 

would apply to existing transport 

category airplanes with a maximum 

takeoff gross weight greater than 75,000 

pounds, by virtue of either the original 

type certification of the airplane or a 

later increase, that are operated under 

part 121 or 129. 


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This final rule applies to certain 

existing transport category, turbinepowered airplanes with a maximum 

takeoff gross weight greater than 75,000 

pounds and a type certificate issued 

after January 1, 1958, regardless of 

whether the maximum takeoff gross 

weight is a result of an original type 

certificate or a later design change. In 

addition, it applies to transport 

category, turbine-powered airplanes 

with a type certificate issued after 

January 1, 1958, if a design change 

approval for which application is made 

after the effective date of the rule has 

the effect of reducing the maximum 

takeoff gross weight from greater than 

75,000 pounds to 75,000 pounds or less. 

It also applies to operators of those 

airplanes being operated under part 121 

or 129. 

1. Type Certificates Issued After January 

1, 1958 

As proposed, applicability of the rule 

was not limited to turbine-powered 

airplanes with type certificates issued 

after January 1, 1958. Everts Air Cargo 

requested that McDonnell Douglas 

Model DC–6 airplanes be excluded from 

applicability, and Boeing requested that 

both the DC–6 and DC–7 be excluded. 

Everts Air Cargo stated that its airplanes 

are non-pressurized, which should 

reduce the risk that they would develop 

WFD. Both Boeing and Everts pointed 

out that §§ 121.370a and 129.16 of the 

Aging Airplane Safety Final Rule apply 

only to certain transport category, 

turbine-powered airplanes with a type 

certificate issued after January 1, 1958. 

The commenters recommended that the 

rule pertaining to WFD apply only to 

those same airplanes. 

The FAA agrees that certain parts of 

the applicability of this final rule should 

align with the Damage Tolerance Data 

Rule and the Aging Airplane Safety 

Final Rule and other aging airplane 

rules, such as EAPAS/FTS. The 

McDonnell Douglas DC–6 and DC–7 

airplanes have not had a damage 

tolerance assessment and have not been 

included in the Damage Tolerance Data 

Rule. In addition, the risk from 

excluding these airplanes is small 

because there are so few of them. 

Therefore, in this final rule the FAA 

has added the phrase ‘‘transport 

category, turbine-powered airplanes 

with a type certificate issued after 

January 1, 1958’’ to the applicability 

provisions of § 26.21 and to the 

operating rules. The change means that 

the following airplanes, which would 

have been affected by the proposal, are 

not subject to this final rule: 

• McDonnell Douglas Models DC–6 

and DC–7. 

• Lockheed Model 1649A–98. 

• Lockheed Model 1049 Series. 

• Lockheed Models 49–46, 149–46, 

649–79, 649A–79, 749–79, and 749A– 

79. 

2. Original Type Certification 

The applicability provision in 

proposed § 25.1807 included airplanes 

with maximum takeoff gross weights 

exceeding 75,000 pounds, as approved 

during original type certification, as 

well as airplanes with lower weights 

that had been increased to greater than 

75,000 pounds through later design 

changes. This applicability provision 

was intended to address two situations. 

In the past, some designers and 

operators avoided applying 

requirements mandated only for 

airplanes over a specific capacity by 

receiving a design change approval for 

a slightly lower capacity. By referencing 

the capacity resulting from original type 

certification, the NPRM removed this 

means of avoiding compliance. 

Similarly, an airplane design could be 

originally certified with a capacity 

lower than the minimum specified in 

the rule, but through later design 

changes, the capacity has been 

increased above this minimum. The 

reference in the NPRM to a later 

increase in capacity was intended to 

ensure that, if this occurs, the design 

would have to meet the requirements of 

the rule. 

The applicability proposed in the 

NPRM did not distinguish among design 

changes based on whether their date of 

application for design approval 

occurred before or after the rule’s 

effective date. That provision in 

proposed § 25.1807 is similar to that for 

the EAPAS/FTS, Fuel Tank 

Flammability, and Damage Tolerance 

Data Rules. In addition, the reference to 

capacity resulting from original type 

certification is common to proposed 

§ 25.1807 and the other rules. The 

agency has determined that the 

approach to applicability under today’s 

rule should be slightly different from 

that used in previous rules. This is to 

avoid requiring design approval holders 

to establish LOVs for models that have 

maximum takeoff gross weights that 

were decreased to 75,000 pounds or less 

by an amended type certificate or 

supplemental type certificate before the 

effective date of today’s rule. Applicants 

for such design changes in the past 

could not have designed the airplanes’ 

capacities to avoid complying with 

today’s requirements, and it is not our 

intent to include them in the 

applicability of this final rule. 

The FAA has revised this section 

(now § 26.21) to apply to transport 

category, turbine-powered airplanes 

with a maximum takeoff gross weight 

greater than 75,000 pounds and a type 

certificate issued after January 1, 1958, 

regardless of whether the maximum 

takeoff gross weight is a result of an 

original type certificate or a later design 

change. This section also applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, if a design change 

approval, for which application is made 

after the effective date of the rule, has 

the effect of reducing the maximum 

takeoff gross weight from greater than 

75,000 pounds to 75,000 pounds or less. 

The FAA has also revised the 

applicability of §§ 121.1115 and 129.115 

to be consistent with the applicability of 

§ 26.21 for existing airplanes. For future 

airplanes for which an LOV is approved 

in accordance with § 25.571 of today’s 

rule, we have retained the requirement 

that §§ 121.1115 and 129.115 apply to 

operators of U.S.-registered transport 

category, turbine-powered airplanes, 

regardless of the maximum takeoff gross 

weight. For future design changes 

reducing the maximum takeoff gross 

weight from greater than 75,000 pounds 

to 75,000 pounds or less, the 

compliance date for operators is 30 

months after the effective date of the 

rule, or the date of design change 

approval, or the date specified in the 

plan approved under § 25.571(b), 

whichever occurs latest. For these 

design changes, unless or until the 

design approval holder complies with 

§ 26.21 by establishing a new LOV, the 

LOV applying to the airplane in the 

absence of the design change would still 

apply. 

3. Airplane Configuration 

This final rule requires that holders of 

type certificates for existing airplanes 

evaluate certain configurations of those 

airplanes for susceptibility to WFD and 

use the results of the evaluation to set 

LOVs for those airplanes. The 

configurations to be evaluated are: 

• All model variations and 

derivatives approved under the type 

certificate, and 

• All structural modifications and 

replacements to those airplanes which 

were mandated by airworthiness 

directives issued to address any 

configuration developed by the design 

approval holder. 

In the NPRM, the FAA proposed 

evaluation of the same airplane 

configurations. 

In their comments, the industry 

representatives on the AAWG, Boeing, 

and Airbus expressed concern about the 

proposed requirement to evaluate all 

structural modifications and 


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30Advisory Circular 120–YY provides guidance 

on which modifications mandated by airworthiness 

directives should be assessed by the design 

approval holder. 

31To develop Table 1, the FAA added airplanes 

to Table 3, deleted airplanes from Table 3, and split 

Boeing Models 737, 747, and 777 airplanes into two 

groups. These airplanes were added: Airbus A318 

and A380; Bombardier CL–600 (2D15 and 2D24); 

and Embraer ERJ–170 and ERJ–190. The following 

airplane models were deleted: Boeing 707 and 720; 

Bombardier CL–44 and BD–700; British Aerospace 

Airbus, Ltd. BAC 1–11; British Aerospace 

(Commercial Aircraft) Ltd. Armstrong Whitworth 

Argosy A.W. 650 Series 101; BAE Systems 

(Operations) Ltd BAe 146A (all models), Avro 146 

RJ70A, Avro RJ85A, and Avro RJ100A. 

replacements mandated by 

airworthiness directives. Airbus stated 

that this approach deviates from all 

previous industry recommendations and 

will lead to a significant increase in 

configurations to be assessed. The 

industry representatives on the AAWG, 

Boeing, and Airbus requested that the 

FAA reconsider this requirement and 

focus only on airworthiness directives 

which have been issued specifically to 

address WFD. 

The FAA issues many airworthiness 

directives which require structural 

modifications or replacements not 

intended to address WFD. These 

required modifications or replacements, 

however, may affect susceptibility of a 

structure to WFD. A modification might 

introduce new details that cause a 

structure which was previously not 

susceptible to WFD to become 

susceptible, or make a change that 

increases susceptibility so that 

previously established maintenance 

actions need to be modified. Because 

today’s rule is intended to address the 

potential for WFD in airplanes as they 

are actually configured, we must 

address these required modifications. It 

would serve no useful purpose to 

evaluate structural configurations which 

no longer exist in service because 

airworthiness directives have required 

modifications to those configurations. 

Modifications mandated by 

airworthiness directives are much fewer 

in number than other modifications, and 

they generally affect airplanes of the 

same model in the same way. Many 

modifications mandated by 

airworthiness directives would not 

affect the potential for WFD; others 

could.30 Therefore, the FAA is today 

issuing this requirement as proposed. 

4. Weight Cutoff 

In the preamble to the proposed rule, 

the FAA stated that the agency had 

considered applying the rule to all 

existing transport category airplanes, 

regardless of the maximum takeoff gross 

weight. The FAA acknowledged that 

using a weight cutoff of greater than 

75,000 pounds excludes approximately 

1,600 regional jets operating under parts 

121 or 129, giving the impression that 

this rule might not align with our ‘‘One 

Level of Safety’’ initiative. However, the 

FAA justifies the proposed weight cutoff 

on the basis of the relatively young age 

of the regional jet fleet. Because those 

airplanes are younger, they have a low 

present risk for WFD. 

Embraer agreed that existing regional 

jet airplanes should not be subject to the 

rule at this time, stating that the 

airplanes have typically been 

certificated to damage tolerance 

requirements. Other commenters—such 

as the National Transportation Safety 

Board, Transport Canada, the Air Line 

Pilots Association (ALPA), EASA, and 

an individual commenter—did not 

agree, because the regional jets are at 

risk of developing WFD as they 

accumulate flight cycles just as larger 

airplanes are. The ALPA recommended 

that the FAA form a study group to 

assess WFD in lighter airplanes. 

Pending a detailed risk analysis, the 

association suggested a weight cutoff of 

12,000 pounds. 

The 75,000 pound weight cutoff was 

based on recommendations from the 

AAWG for WFD rulemaking. The 

overwhelming majority of passengers 

and cargo are carried by airplanes with 

a maximum gross takeoff weight of 

greater than 75,000 pounds. Inclusion of 

airplanes below that limit and above 

12,500 pounds is under study by the 

FAA and if service experience shows a 

need to include those airplanes, 

rulemaking will be considered to 

include them. 

The FAA’s highest priority is to 

address the oldest airplanes at highest 

risk of WFD—namely, airplanes with a 

maximum takeoff gross weight greater 

than 75,000 pounds. However, the FAA 

recognizes that the lighter and relatively 

younger regional jets will also be at risk 

of developing WFD as they accumulate 

flight cycles. We will reassess the fleet, 

including those airplanes below 75,000 

pounds, after this rule has been 

implemented, to determine whether 

further rulemaking is necessary. 

5. Default LOVs and Excluded Airplanes 

a. Table 1—Default LOVs 

In the proposed operational 

requirements in the NPRM, the FAA 

inadvertently created an ambiguity 

regarding the obligations of operators of 

airplanes for which the design approval 

holder might fail to establish an LOV as 

required. While the FAA fully 

anticipates that affected design approval 

holders will comply with the 

requirements of this final rule, there is 

a need to clearly provide for what 

happens if one or more does not. As 

proposed, paragraph (a) of §§ 121.1115 

and 129.115 would apply to operators of 

airplanes for which an LOV ‘‘has been 

established.’’ Paragraph (b) of these 

sections requires that operators 

incorporate approved LOVs. 

Our expectation was that, if a design 

approval holder failed to comply with 

the requirement to obtain approval for 

an LOV, the operator or operators, in 

order to continue to operate the affected 

airplanes, would themselves obtain the 

necessary approval. Because they would 

not have access to the design approval 

holder’s data necessary to perform a 

WFD evaluation, they would likely have 

to rely on the design service goals and 

extended service goals set forth in Table 

3 of the NPRM (see below). As stated in 

the NPRM, ‘‘After June 18, 2008, an 

affected operator could not operate an 

airplane unless the operator has 

incorporated an Airworthiness 

Limitations section approved under 

Appendix H to part 25 or § 25.1807 into 

its maintenance program.’’ 

The FAA now recognizes that the 

final rule should explicitly define 

operators’ obligations if the design 

approval holder fails to comply. 

Therefore, the FAA has revised the 

operational rules to state that, in the 

absence of an approved LOV, the 

operator must incorporate the 

applicable LOV specified in Table 1 31 of 

either § 121.1115 or § 129.115. The table 

also adds flight hour numbers for design 

service goals for airplanes for which that 

information was available. 

The inclusion of default LOVs in 

Table 1 does not prevent an operator 

from developing its own LOV under 

§ 26.23 of this final rule. The rule 

specifies that— 

• The design approval holder must 

establish an LOV, and 

• If an LOV is not approved, an 

operator must use the default LOV in 

Table 1. If an operator later chooses to 

establish an LOV under § 26.23, that 

LOV will be considered an extended 

LOV. 

This provision eliminates any need 

for operators to obtain a separate 

approval for these ‘‘default’’ LOVs. It 

also eliminates the risk that a relatively 

young airplane would be grounded as of 

an operator’s compliance date simply 

because the FAA had not approved an 

LOV for that airplane. 

Boeing stated that the default LOVs 

published in the Technical Document 

are without context and could be 

misused. Boeing said that it could 

provide more appropriate numbers to 


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use, but that these numbers should be 

removed from the rule because Boeing 

intends to comply with the rule. 

The default LOVs in Table 2 of 

§ 121.1115 and § 129.115 are intended 

to be used by persons who may choose 

to operate one of the excluded airplanes. 

They may also be used by other 

operators if a design approval holder is 

late in establishing an LOV, in order to 

prevent airplanes with fewer 

accumulated flight cycles and flight 

hours than the default LOV from being 

grounded. A few airplanes, such as the 

Airbus A380, already have an 

operational limitation included in their 

Airworthiness Limitations section. 

These are referenced in the table by a 

NOTE, and may be used as a default 

LOV. 

FIGURE 3—COMPARISON OF NPRM DESIGN AND EXTENDED SERVICE GOALS AND FINAL RULE DEFAULT LOVS

Airplane model 

NPRM table 3 Final rule §§ 121.1115 and 

129.115 table 1 

Design and Extended Service Goals 

(flight cycles) 

Default LOVs 

[flight cycles (FC) or flight 

hours (FH)] 

Airbus: 

A300 B2 Series 32 ........................................................................ 48,000 ........................................................... 48,000 FC 

A300 B4–100 Series 33 ................................................................ 40,000 ........................................................... 40,000 FC 

A300 B4–203 ............................................................................... 34,000 ........................................................... 34,000 FC 

A300–600 Series 34 ..................................................................... 30,000 ........................................................... 30,000 FC/67,500 FH 

A310–200 Series (all models) ..................................................... 40,000 ........................................................... 40,000 FC/60,000 FH 

A310–300 Series (all models) ..................................................... 35,000 ........................................................... 35,000 FC/60,000 FH 

A318 Series (all models) ............................................................. None provided ............................................... 48,000 FC/60,000 FH 

A319 Series (all models) ............................................................. 48,000 ........................................................... 48,000 FC/60,000 FH 

A320–100 Series (all models) 35 ................................................. 48,000 ........................................................... 48,000 FC/48,000 FH 

A320–200 Series (all models) 35 ................................................. 48,000 ........................................................... 48,000 FC/60,000 FH 

A321 Series (all models) ............................................................. 48,000 ........................................................... 48,000 FC/60,000 FH 

A330–200, –300 Series (except WV050 family) (non enhanced) 36.40,000 ........................................................... 40,000 FC/60,000 FH 

A330–200, –300 Series WV050 family (enhanced) 36 ................ 40,000 ........................................................... 33,000 FC/100,000 FH 

A330–200 Freighter Series ......................................................... None provided ............................................... NOTE38

A340–200, 300 Series(except WV 027 and WV050 family) (non 

enhanced) 37.

20,000 ........................................................... 20,000 FC/80,000 FH 

A340–200, 300 Series WV 027 (non enhanced) 37 .................... 20,000 ........................................................... 30,000 FC/60,000 FH 

A340–300 SeriesWV050 family (enhanced) 37 ............................ 20,000 ........................................................... 20,000 FC/100,000 FH 

A340–500, 600 Series (all models) 37 ......................................... 20,000 ........................................................... 16,600 FC/100,000 FH 

A380–800 Series (all models) ..................................................... None provided ............................................... NOTE39

Boeing: 

Boeing 707 (–100 Series and –200 Series) ................................ 20,000 ........................................................... Excluded per § 26.21(g) 

Boeing 707 (–300 Series and –400 Series) ................................ 20,000 ........................................................... Excluded per § 26.21(g) 

717 (all models) ........................................................................... 60,000 ........................................................... 60,000 FC/60,000 FH 

Boeing 720 .................................................................................. 30,000 ........................................................... Excluded per § 26.21(g) 

727 (all models) ........................................................................... 60,000 ........................................................... 60,000 FC 

737 (Classics): 737–100, –200, –200C, –300, –400, –500 40 .... 75,000 ........................................................... 75,000 FC 

737 (NG): 737–600, –700, –700C, 800, 900 40 ........................... 75,000 ........................................................... 75,000 FC 

737–900ER .................................................................................. None provided ............................................... 75,000 FC 

747 (Classics): 747–100, –100B, –100B SUD, –200B, –200C, 

–200F, –300, –747SP, 747SR 41.

20,000 ........................................................... 20,000 FC 

747–400: 747–400, –400D, –400F 41 .......................................... 20,000 ........................................................... 20,000 FC 

757 (all models) ........................................................................... 50,000 ........................................................... 50,000 FC 

767 (all models) ........................................................................... 50,000 ........................................................... 50,000 FC 

777–200, –300 42 ......................................................................... 44,000 ........................................................... 40,000 FC 

777–200LR, 777–300ER 42 ......................................................... 44,000 ........................................................... 40,000 FC 

777F ............................................................................................. None provided ............................................... 11,000 FC 

Bombardier: 

CL–44D4 and CL–44J ................................................................. 20,000 ........................................................... Excluded per § 26.21(g) 

CL–600: 2D15 (Regional Jet Series 705), 2D24 (Regional Jet 

Series 900).

None provided ............................................... 60,000 FC 

British Aerospace Airbus, Ltd.: 

BAC 1–11 (all models) ................................................................ 85,000 ........................................................... Excluded per § 26.21(g) 

British Aerospace (Commercial Aircraft) Ltd.: 

Armstrong Whitworth Argosy A.W. 650 Series 101 .................... 20,000 ........................................................... Excluded per § 26.21(g) 

BAE Systems (Operations) Ltd.: 

BAE 46 (all models) and Avro 146 RJ70A, RJ85A and RJ100A 

(all models).

50,000 ........................................................... Excluded per § 26.21(g) 

Embraer: 

ERJ 170 (all models) ................................................................... None provided ............................................... NOTE43

ERJ 190 (all models) ................................................................... None provided ............................................... NOTE44

Fokker: 

F.28 Mark 70, Mark 100 (all models) .......................................... 90,000 ........................................................... 90,000 FC 

Lockheed: 

300–50A01 (USAF C 141A) ........................................................ 20,000 ........................................................... Excluded per § 26.21(g) 

L–1011 (all models) ..................................................................... 36,000 ........................................................... 36,000 FC 

188 (all models) ........................................................................... 26,600 ........................................................... 26,600 FC 


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FIGURE 3—COMPARISON OF NPRM DESIGN AND EXTENDED SERVICE GOALS AND FINAL RULE DEFAULT LOVS— 

Continued 

Airplane model 

NPRM table 3 Final rule §§ 121.1115 and 

129.115 table 1 

Design and Extended Service Goals 

(flight cycles) 

Default LOVs 

[flight cycles (FC) or flight 

hours (FH)] 

382 (all models) ........................................................................... 20,000 ........................................................... 20,000 FC/50,000 FH 

1649A–98 .................................................................................... 20,000 ........................................................... Excluded per § 26.21(a) 

1049–54, 1049B–55, 1049C–55, 1049D–55, 1049E–55, 

1049F–55, 1049G–8249–46, 149–46, 649–79, 649A–79.

20,000 ........................................................... Excluded per § 26.21(a) 

749–79, 749A–79 ........................................................................ 20,000 ........................................................... Excluded per § 26.21(a) 

McDonnell Douglas: 

DC–6 45 ........................................................................................ 20,000 ........................................................... Excluded per § 26.21(a) 

DC–6A (all models) 45 .................................................................. 20,000 ........................................................... Excluded per § 26.21(a) 

DC–6B (all models) 45 .................................................................. 20,000 ........................................................... Excluded per § 26.21(a) 

DC–7 (all models) 45 .................................................................... 20,000 ........................................................... Excluded per § 26.21(a) 

DC–8, –8F (all models) ............................................................... 50,000 ........................................................... 50,000 FC/50,000 FH 

DC–9 (all models) ........................................................................ 100,000 ......................................................... 100,000 FC/100,000 FH 

MD–80 (all models) ..................................................................... 50,000 ........................................................... 50,000 FC/50,000 FH 

MD–90 (all models) 46 .................................................................. 60,000 ........................................................... 60,000 FC/90,000 FH 

DC–10–10, –15 (all models) ....................................................... 42,000 ........................................................... 42,000 FC/60,000 FH 

DC–10–30, –40, –10F, –30F, –40F (all models) ........................ 30,000 ........................................................... 30,000 FC/60,000 FH 

MD–10–10F (all models) ............................................................. 42,000 ........................................................... 42,000 FC/60,000FH 

MD–10–30F (all models) ............................................................. 30,000 ........................................................... 30,000 FC/60,000 FH 

MD–11, –11F (all models) ........................................................... 20,000 ........................................................... 20,000 FC/60,000 FH 

Airplanes with Maximum Takeoff Gross Weight Changes: 

All airplanes whose maximum takeoff gross weight has been 

decreased to 75,000 pounds or below after January 14, 2011 

or increased to greater than 75,000 pounds at any time by 

an amended type certificate or supplemental type certificate.

Design service goals and extended service 

goals for airplanes whose weight has 

been changed are unknown.

There are no default LOVs 

for airplanes whose 

weight has been 

changed. 

32 Listed as A300 B2–1A, B2–1C and B2K–3C in the NPRM. 33 Listed as A300 B4–2C and B4–103 in the NPRM. 34 Listed as A300 B4–600 Series, B4–600R Series, and F4–600R Series in the NPRM. 35 Listed as A320 (all models) in the NPRM. 36 Listed as A330 (all models) in the NPRM. 37 Listed as A340 (all models) in the NPRM. 38Airplane operation limitation is stated in the Airworthiness Limitation section. 39Airplane operation limitation is stated in the Airworthiness Limitation section. 40 Listed as Boeing 737 in the NPRM. 41 Listed as Boeing 747 in the NPRM. 42 Listed as Boeing 777 in the NPRM. 43Airplane operation limitation is stated in the Airworthiness Limitation section. 44Airplane operation limitation is stated in the Airworthiness Limitation section. 45Airplane certificated before 1958. 46 Listed as MD–90–30 in the NPRM. 

b. Table 2—Airplanes excluded from 

§ 26.21 

Section 26.21 specifically excludes 

models of airplanes from today’s rule if 

no airplanes of that model are operating 

under part 121 or 129. Today’s revisions 

to parts 121 and 129 requiring that 

operators incorporate LOVs into their 

structural maintenance programs 

include applicability to operators of 

airplanes that have been excluded under 

§ 26.21 should the operator later decide 

to operate one of them. 

In the NPRM, the FAA proposed 

excluding airplanes not operated under 

part 121 or 129. The agency proposed 

exclusion from the rule for: 

• Bombardier BD–700. 

• Gulfstream GV. 

• Gulfstream GV–SP. 

• British Aerospace, Aircraft Group, 

and Societe Nationale Industrielle 

Aerospatiale Concorde Type 1. 

The FAA requested comments on the 

feasibility and benefits of including or 

excluding these airplanes. The agency 

also requested comments on the 

feasibility of including or excluding any 

other transport category airplanes with 

a maximum takeoff gross weight greater 

than 75,000 pounds from the 

requirements of this provision, whether 

or not they are operated under part 121 

or 129. 

Several commenters disagreed with 

the applicability of the rule, as 

proposed. The National Transportation 

Safety Board recommended that the 

final rule also apply to airplanes 

operated under part 135 because they 

may be at equal or greater risk of 

developing WFD compared to those 

operated under parts 121 or 129. 

An individual commenter suggested 

that the FAA delete the list of airplanes 

proposed for exclusion because it gives 

preferential treatment to certain 

airplanes. This commenter added that 

an operator had planned to use 

Gulfstream GV airplanes for part 121 

operations but chose not to do so only 

for financial reasons. If an operator did 

decide to operate an excluded airplane 

under part 121 or 129, said the 

commenter, there would be no 

operational limit and no associated 

maintenance actions to preclude WFD 

in that airplane. Although this 

commenter did not support having a list 

of excluded airplanes in the rule, he 

suggested—based on the agency’s stated 

rationale in the NPRM—that we add the 

following airplanes to the list: 

• The Douglas DC–6, DC–6A, and 

DC–7. 

• The Lockheed 049, 149, 649, 749, 

1049, 1649, 188, 300, and 382. 

• The Boeing 707 and 720. 


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47Agreement between the Government of the 

United States of America and the Government of 

Canada for Promotion of Aviation Safety, June 12, 

2000. 

We have reconsidered our rationale 

for the list of excluded airplanes 

proposed in the NPRM. Those airplanes 

have a maximum takeoff gross weight 

greater than 75,000 pounds but are not 

currently operating under part 121 or 

129. Therefore, there is no reason to 

require the design approval holders to 

establish LOVs for them. We have 

decided to retain on the list the models 

originally proposed for exclusion from 

the rule and, in response to comments, 

and to be consistent with other aging 

airplane rules, have added other models 

which are not operated under part 121 

or 129. The complete list is shown 

below. 

(1) Bombardier BD–700. 

(2) Bombardier CL–44. 

(3) Gulfstream GV. 

(4) Gulfstream GV–SP. 

(5) British Aerospace, Aircraft Group, 

and Societe Nationale Industrielle 

Aerospatiale Concorde Type 1. 

(6) British Aerospace (Commercial 

Aircraft) Ltd., Armstrong Whitworth 

Argosy A.W. 650 Series 101. 

(7) British Aerospace Airbus, Ltd., 

BAC 1–11. 

(8) BAE Systems (Operations) Ltd., 

BAe 146. 

(9) BAE Systems (Operations) Ltd., 

Avro 146. 

(10) Lockheed 300–50A01 (USAF 

C141A). 

(11) Boeing 707. 

(12) Boeing 720. 

(13) deHavilland D.H. 106 Comet 4C. 

(14) Ilyushin Aviation IL–96T. 

(15) Bristol Aircraft Britannia 305. 

(16) Avions Marcel Dassault-Breguet 

Aviation Mercure 100C. 

(17) Airbus Caravelle. 

(18) D & R Nevada, LLC, Convair 

Model 22. 

(19) D & R Nevada, LLC, Convair 

Model 23M. 

The FAA recognizes that it is 

possible—as suggested by the individual 

commenter—that in the future an 

operator could decide to operate an 

‘‘excluded’’ airplane under part 121 or 

129. Therefore, in this final rule 

§§ 121.1115 and 129.115 are revised to 

provide that no airplane listed in § 26.21 

can be operated under part 121 or 129 

unless an LOV for the airplane has been 

incorporated into the operator’s 

structural maintenance program. The 

operational rules state that, in the 

absence of an approved LOV, the 

operator must incorporate the 

applicable default LOV specified in 

Table 2 of either §§ 121.1115 or 129.115. 

Those default LOVs are based on Table 

3 of the NPRM. As stated in the NPRM, 

Table 3 used design service goals and 

extended service goals that were based 

on information from design approval 

holders or on a conservative estimate by 

the FAA. It did not include the Comet 

4C, IL–96T, Britannia 305, Mercure 

100C, Caravelle, Convair Model 22, or 

Convair Model 23M. To develop those 

default LOVs, the FAA treated flightcycle or flight-hour data that was 

available for those airplanes as fatigue 

test data and reduced it by a factor of 

two. This approach is based in part on 

AC 25.571–1X for new airplanes. 

6. Bombardier Airplanes 

Bombardier asked for clarification of 

the applicability of the proposed rule to 

several of its models and their 

derivatives. Specifically, the company 

asked about the following airplanes: 

Models CL 600 Challenger 870 and 

890: Bombardier asked whether they 

should be added to the list of excluded 

airplanes in proposed § 25.1807(i). 

The CL 600 Challenger 870 and 890 

do not currently have type certificates 

issued by the U.S. Therefore, there are 

no N-registered airplanes operating 

under either part 121 or 129. As a result, 

this final rule does not apply to them at 

this time. However, if Bombardier were 

to apply for a U.S. type certificate before 

the effective date of this final rule, the 

company would have to comply by the 

compliance date in § 26.21. Even if 

Bombardier were to apply after the 

effective date of the rule, the company 

would be subject to requirements of 

§ 26.21 because the Bilateral Aviation 

Safety Agreements (BASA) 47 with 

Canada allow the U.S. to impose 

additional requirements in the interest 

of safety. Other airplanes in similar 

circumstances would be handled in the 

same way. 

Model CL 600 derivatives—RJ 701 ER, 

RJ 701 LR, all RJ 705 airplanes, and all 

RJ 900 airplanes: Bombardier noted that 

Table 3 in the NPRM, titled Design and 

Extended Service Goals, does not list 

these models. 

The CL 600 derivatives RJ 705 and RJ 

900 were inadvertently left off Table 3 

of the NPRM. This final rule applies to 

Bombardier models RJ 705 series and RJ 

900 series because their maximum 

takeoff gross weight is greater than 

75,000 pounds, and they are operated 

under part 121 or 129. They have been 

added to Table 1, which is the 

applicability table for this final rule. 

Today’s rule does not apply to 

Bombardier RJ 701 series airplanes 

because their maximum takeoff gross 

weight is not greater than 75,000 

pounds. 

Model CL 44: These airplanes were 

previously exempted from the other 

aging airplane rules, both proposed and 

final, on the basis of their age and the 

very small number remaining in service. 

Bombardier Model CL 44 is not 

operated under either part 121 or 129 

and, therefore, the FAA has revised the 

list of excluded airplanes in § 26.21 of 

today’s rule to include Bombardier 

Model CL 44. 

7. Intrastate Operations in Alaska 

Lynden Air Cargo requested that the 

NPRM pertaining to WFD be withdrawn 

in its entirety. Alternatively, the 

commenter requested that Lockheed 

Model 382 airplanes be excluded from 

the rule and that all air carriers engaged 

in intrastate operations in Alaska be 

excluded. In support of this request, the 

commenter gave the following reasons: 

• There is no replacement airplane 

with the necessary lift and operational 

characteristics. 

• The L–382 airplanes are not used to 

carry passengers. 

• It is in the public interest to 

maintain the unique capabilities of the 

L–382 in Alaska where it supports 

remote communities and projects with 

no roads or waterways and supports the 

U.S. military during critical campaigns 

and the ongoing war on terrorism. 

Lynden Air Cargo also asked that it be 

excluded from § 121.909. 

Senator Murkowski of Alaska and the 

late Senator Stevens stated that the rule, 

as proposed, would have severe 

consequences to residents and cargo 

carriers operating in that State. Senator 

Stevens referred to Section 1205 of the 

Federal Aviation Reauthorization Act of 

1996 (49 U.S.C. 40113(f)), which 

requires that—when modifying 

regulations affecting intrastate aviation 

in Alaska—the FAA consider the extent 

to which Alaska is not served by 

transportation modes other than 

aviation. Accordingly, Senator Stevens 

requested that the FAA exempt all 

intrastate operations in Alaska and the 

interstate operations of the six Lockheed 

L–382G airplanes operated by Lynden 

Air Cargo. The senator pointed out that 

the L–382G is out of production and 

there is no suitable replacement 

available. 

Several other commenters addressed 

operational limits for Lockheed Models 

L–382E and G, although they did not 

discuss operation of these airplanes in 

Alaska. Specifically, Transafrik 

International asked that Lockheed 

Models L–382E and G be removed from 

Table 3 or that their operational limit be 

increased to at least 60,000 cycles. The 

commenter added that the airplanes are 

no longer in production and there is no 


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48 67 FR 72726, December 6, 2002. 

replacement airplane able to take off 

and land on short, unimproved runways 

with the payloads required. A comment 

from Lockheed Martin estimated—based 

on certain inspections and 

modifications which it had performed 

on the outer and center wing structure— 

that the LOV for the Lockheed Model L– 

382 is 50,000 flight hours but would no 

doubt be changed to at least 75,000 

flight hours, to accommodate usage in 

the fleet. Lockheed Martin also 

identified maintenance actions that 

should be performed on the wing 

structure to operate to that limit. The 

commenter stated that, regardless of any 

FAA decision on implementation of the 

rule, the company will continue to 

ensure that operators of Lockheed 

Model L–382 model aircraft are 

provided with inspection procedures 

and replacement actions that effectively 

mitigate the risk of failure due to WFD. 

Consistent with 49 U.S.C. 40113(f), 

the FAA has carefully considered the 

potential impact of this rulemaking on 

Alaska intrastate operators to determine 

whether intrastate service in Alaska 

would be adversely affected. Airplanes 

to which this final rule is applicable are 

not operated solely in intrastate 

commerce in Alaska. Therefore, 

contrary to the commenters’ assertions, 

the FAA has determined that there 

would not be an adverse effect on 

intrastate air transportation in Alaska 

and that regulatory distinctions are not 

appropriate. 

The Lockheed L–382G operated by 

Lynden Air Cargo is operated under 14 

CFR part 121, Operating Requirements: 

Domestic, Flag, and Supplemental 

Operations and operates interstate as 

well as to foreign destinations. The FAA 

has decided against excluding the L– 

382G from requirements of §§ 121.1115 

and 129.115 for those airplanes in 

interstate operation. The safety rationale 

for these rules applies equally to that 

airplane. In accordance with 14 CFR 

part 11, Lynden Air Cargo may submit 

a petition for exemption from those 

rules. Such a petition must state (1) why 

granting such an exemption would be in 

the public interest and (2) why a grant 

of exemption would not adversely affect 

safety or how it would provide a level 

of safety equivalent to the regulation. 

Regarding Lynden Air Cargo’s request 

for exclusion from § 121.909, that 

requirement, which was formerly 

designated as § 121.370(a), has been in 

effect since November 1, 2002.48 The 

FAA has not made any changes to that 

rule other than changing its section 

number. 

The FAA encourages Transafrik and 

Lynden Air Cargo as well as other 

operators of Model L–382G to work with 

Lockheed Martin regarding the 

establishment of the LOV for the model. 

8. Composite Structures 

The Modification and Replacement 

Parts Association (MARPA) and Airbus 

asked that the FAA clarify applicability 

of the rule to structure made of 

composite materials, and MARPA 

recommended that composite structure 

should be treated the same as metallic 

structure. 

There is an increasing trend for 

manufacturers to use composite 

materials to build airplanes. This 

structure wears differently than metallic 

structure. For example with metallic 

structure, repeated loads or 

environmental exposure cause fatigue 

cracking or corrosion. With composite 

structure, repeated loads or 

environmental exposure cause general 

degradation (such as cracking, 

delamination, and oxidative breakdown 

of the resin) and accumulation of local 

damage (such as wearing out of fastener 

holes and handling damage, or water 

ingression between composite layers, 

followed by freeze-thaw cracking of the 

core). 

The FAA issued AC 20–107B to 

provide guidance for certifying 

composite structures, including 

guidance for evaluating composite 

structure relative to the damage 

tolerance requirements of § 25.571. 

The objective of this final rule is to 

address the normal fatigue wear out of 

metallic structure. Although the trend in 

industry is to use composite structure as 

much as possible, a significant 

percentage of a new airplane may still 

be built of metal. Full-scale fatigue test 

evidence would be necessary to 

demonstrate that WFD will not occur in 

metallic structure of the airplane. It 

would also be necessary for the design 

approval holder for the airplane to 

develop an LOV to limit the operation 

to the point in time up to which it has 

been demonstrated that WFD will not 

occur in the airplane’s metallic 

structure. 

The FAA will continue to evaluate 

whether rulemaking is necessary to 

address the normal wear of composite 

structures. 

K. Harmonization 

A number of commenters, including 

industry representatives on the AAWG, 

FedEx, Boeing, Embraer, the National 

Air Cargo Association (NACA), AWAS, 

and Airbus noted that the WFD NPRM 

has not been harmonized with the 

European Aviation Safety Agency 

(EASA), which has issued Notice of 

Proposed Amendment (NPA) 05–2006 

on this subject, and other national 

aviation authorities. The commenters 

pointed out that the Initial Regulatory 

Evaluation did not consider the cost of 

failing to harmonize the rule with other 

airworthiness authorities. Airbus also 

questioned whether the evaluation 

addressed costs associated with 

importing into the United States 

airplanes that have not complied with 

the rule, especially if the rule is not 

harmonized with other airworthiness 

authorities. 

They recommended that the FAA 

harmonize the rule with those 

authorities before issuing it. According 

to the commenters, lack of 

harmonization could cause the 

following problems: 

1. It could create a significant 

challenge to future certification projects, 

encouraging unilateral and possibly 

arbitrary certification activities. 

2. There could be a substantial 

negative economic impact with respect 

to the transfer, lease, or sale of aircraft 

between the U.S. and other countries. 

Commenters suggested that bilateral 

agreements be amended to support the 

transfer of used aircraft subject to the 

final rule. 

3. The FAA and EASA could have 

different approaches to WFD. 

4. Type certificate holders from other 

countries may not be given the same 

priority and allocation of FAA resources 

as are type certificate holders from this 

country, resulting in delayed approval 

for applications from other countries. 

Boeing, EASA, and Airbus requested 

that the FAA include the requirement to 

evaluate certain repairs, alterations, and 

modifications to align its requirements 

with those being proposed by EASA. 

The FAA is working closely with 

EASA and other national airworthiness 

authorities to harmonize this final rule 

as much as possible. On April 25, 2006, 

EASA published NPA 05–2006, entitled 

Ageing Aeroplane Structures. That 

notice proposed technical guidance to 

be used for developing programs for 

continuing structural integrity, to ensure 

that the structure of aging airplanes is 

adequately maintained throughout their 

operational lives. Among other things, 

the notice proposed guidance for 

addressing WFD in existing airplane 

models. The FAA has provided 

comments on that proposed rulemaking. 

EASA is considering our comments and 

has discussed them with us. 

Many of the changes made to our 

proposed rule will facilitate 

harmonization with national 

airworthiness authorities. Some of these 

changes are the following: 


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1. The design approval holder 

requirements proposed in the NPRM as 

part 25, subpart I, are now contained in 

a new part 26 to harmonize more easily 

with the regulatory structure of other 

national airworthiness authorities. 

2. This final rule uses the term ‘‘limit 

of validity’’ rather than ‘‘initial 

operational limit’’ to align more closely 

with other national airworthiness 

authorities. 

3. This final rule uses compliance 

dates that specify a phased approach for 

establishing the LOV for existing 

airplane models. NPA 05–2006 links 

compliance dates to design service 

goals. As discussed above, the FAA has 

concluded that the latter approach 

creates unnecessary complexity and 

uncertainty. We have submitted 

comments about this matter to EASA 

and are in discussions about it. In terms 

of establishing an LOV, the technical 

guidance in AC 120–YY is consistent 

with EASA’s technical guidance in NPA 

05–2006. 

4. With respect to removal of 

requirements pertaining to repairs, 

alterations, and modifications, the FAA 

is working closely to harmonize this 

final rule with the rule EASA is 

developing but has not yet published for 

public comment. 

5. Finally, the changes to § 25.571 are 

based on a recommendation of the 

General Structures Harmonization 

Working Group of ARAC. Development 

of the October 2003 recommendation 

pertaining to WFD involved 

harmonization between U.S. and 

European requirements. 

L. The Regulatory Evaluation for the 

NPRM 

The estimated present value cost of 

this final rule is about $3.6 million, 

while the estimated present value cost 

of the NPRM was estimated to be about 

$360 million. The estimated benefits of 

this final rule are worth $4.8 million in 

present value and are based on 

managing WFD with maintenance 

actions developed under this final rule 

versus the current practice of issuing 

airworthiness directives as WFD is 

found. The estimated present value 

benefits of the NPRM consisted of $726 

million of accident prevention benefits 

and $83 million of detection benefits for 

total benefits of $809 million. 

We received many comments 

regarding the validity of the regulatory 

evaluation of the proposed rule on 

WFD. In general, commenters stated that 

the potential benefits of the rule seemed 

to be overstated, and the potential costs 

seemed to be understated. Therefore, 

commenters challenged the conclusion 

that the benefits of the rule justify the 

costs. The commenters included 

Lockheed Martin, Boeing, Airbus, 

Bombardier, NACA, the CAA, ATA, 

FedEx, United Parcel Service, AWAS, 

American Airlines, Lynden Air Cargo, 

industry representatives on the AAWG, 

and an individual commenter. 

1. Benefits of Proposed Rule 

Some commenters questioned how a 

benefit of $726 million could be 

attributable to accident prevention 

when there have been no accidents 

related to WFD since the Aloha Airlines 

accident in 1988. The NACA and other 

commenters also argued that the 

regulatory evaluation makes a false 

assumption when it defines the cost 

benefit number for avoiding fleet 

grounding. Finally, the ATA and several 

other commenters suggested that 

projected benefits would decrease if the 

regulatory evaluation were updated to 

include data from the years 1974 

through 1983 and 2000 through 2005. 

Today’s rule establishes a consistent 

approach to management of aging 

airplanes so that they are not operated 

to the point where WFD occurs. Thus 

the potential benefit of the rule is 

preventing catastrophic structural 

failure in flight that could result in loss 

of lives and loss of the airplane. Other 

benefits of the rule are costs avoided 

under the current system. Relying on 

the issuance of airworthiness directives 

to address WFD—whenever it happens 

to be discovered—causes unscheduled 

down time. The issuance of emergency 

airworthiness directives and 

immediately adopted rules may result in 

the unscheduled removal from service 

of a fleet of airplanes. 

This final rule requires a design 

approval holder to establish an LOV for 

an airplane that reflects the fatigue 

characteristics of the airplane structure. 

If the WFD evaluation determines that 

maintenance actions are necessary to 

reach this LOV, the FAA would adopt 

them through the normal airworthiness 

directive process, allowing opportunity 

for notice and comment and 

accomplishment of required actions 

during scheduled maintenance. As 

such, the costs of these maintenance 

actions would be lower than if the FAA 

adopted emergency airworthiness 

directives or immediately adopted rules 

mandating the same actions as a result 

of in-service occurrences of WFD. As 

discussed below, the FAA expects very 

few airplanes to be retired solely 

because they reach their LOV. We have 

also taken this into account. 

Our revised regulatory evaluation lists 

three benefits of the rule, namely 

(1) Prevention of accidents; 

(2) Extension of the economic life of 

the airplane with corresponding 

revenues from that additional economic 

life; and 

(3) Near elimination of emergency 

airworthiness directives pertaining to 

WFD, which significantly reduces 

downtime associated with urgent 

unscheduled maintenance. The 

quantified benefit of the final rule is 

based solely on this third benefit, which 

is valued at $9.8 million or, evenly 

distributed over 20 years, a present 

value of approximately $4.8 million. 

2. Costs of Proposed Rule 

a. Need To Know LOVs To Determine 

Cost 

Some commenters stated that, if the 

operational limit for each airplane 

model were not known, then the cost of 

the rule could not be determined. 

In our Initial Regulatory Evaluation, 

the agency estimated the costs of initial 

operational limits to operators by using 

the design service goal for each airplane 

model as the initial operational limit. 

Those cost estimates would be expected 

to be higher than estimates based on 

LOVs that design approval holders 

anticipate establishing because in most 

cases, these LOVs are expected to 

exceed the design service goals. During 

the comment period, manufacturers 

provided the LOVs that they anticipate 

they will be establishing under today’s 

rule. Those LOVs were 33% to 180% 

higher than the airplane’s design service 

goal. Accordingly, our analysis in the 

Final Regulatory Evaluation uses these 

anticipated LOVs and indicates a lower 

cost to operators than was initially 

projected. 

Airbus stated that not all of its models 

will have LOVs from 33% to 180% 

beyond the airplane’s design service 

goal. Airbus will have LOVs for some 

models that will be equal to the 

airplane’s design service goal. Although 

some of Airbus’s LOVs are equal to the 

design service goal, which makes the 

LOVs span a shorter time, we still do 

not anticipate that any Airbus airplanes 

will need to be retired during the 20- 

year analysis period as a result of this 

final rule. 

FedEx, Northwest Airlines, and ATA 

argued that operator cost estimates are 

not credible if they are based on 

anticipated LOVs instead of LOVs that 

have been accepted by the FAA and 

industry. It is for this reason that FedEx 

further argued that an operational rule 

must be proposed after the design 

approval holder’s LOVs have been 

approved by the FAA. This would also, 

noted the commenter, provide the 


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public with the opportunity to comment 

on those LOVs. 

The FAA measures the economic loss 

to operators of retiring an airplane at 

LOV instead of at a planned future 

retirement date. The FAA considers that 

this is a reasonable way to estimate 

compliance costs and that, ultimately, 

the LOVs that are accepted by the FAA 

and industry will be very close to those 

anticipated LOVs that the FAA has 

received from industry and used for 

these estimates of cost. 

b. Need To Know Maintenance Actions 

To Determine Cost 

Some commenters suggested that the 

costs associated with maintenance 

actions to preclude WFD prior to 

reaching the LOV either could not be 

determined or were substantially 

underestimated because the actions 

were not yet developed. Other 

commenters indicated that costs used in 

the regulatory evaluation do not 

accurately reflect operators’ costs. They 

said, for example, that estimates of the 

number of hours needed to accomplish 

inspections, the number of inspections 

needed in a maintenance visit, and the 

number of days an airplane is out of 

service to accomplish maintenance did 

not reflect the actual experience of 

operators. Boeing added that the overall 

cost of the rule is difficult to determine 

because there will be costs related to 

maintenance actions required by 

airworthiness directives. 

Although this final rule allows design 

approval holders to establish LOVs 

without relying on maintenance actions, 

the FAA expects most design approval 

holders will adopt LOVs that rely on 

such actions. As discussed in the 

NPRM, design approval holders are not 

required to identify and develop 

maintenance actions if they can show 

that such actions are not necessary to 

prevent WFD before the airplanes reach 

the LOV. As discussed in the Final 

Regulatory Evaluation, the FAA 

anticipates that at least Boeing will 

propose LOVs that will depend upon 

accomplishment of future maintenance 

actions. This is consistent with Boeing’s 

current practice of developing service 

information that defines the 

maintenance actions to address WFD in 

its products. However, any maintenance 

actions necessary to reach the LOV will 

be mandated by airworthiness directives 

through separate rulemaking actions, so 

their costs are not attributable to this 

final rule. This is also consistent with 

the current practice of issuing 

airworthiness directives to address 

unsafe conditions associated with WFD. 

The FAA will provide cost estimates 

when issuing the airworthiness 

directives for any maintenance actions 

necessary to prevent WFD. 

The FAA recognizes that this final 

rule is unusual in that it may depend 

upon future rulemaking to fully achieve 

its safety objectives. In the context of 

WFD, this approach is necessary to 

enable design approval holders to 

propose LOVs that allow operators the 

longest operational lives for their 

airplanes, while still ensuring freedom 

from WFD. This approach allows for an 

implementation strategy that provides 

flexibility to design approval holders in 

determining the timing of service 

information development (with FAA 

approval), while providing operators 

with certainty regarding the LOV 

applicable to their airplanes. The FAA 

has issued many airworthiness 

directives in the past to address WFD 

issues, and the agency anticipates that 

the approach adopted today will 

interface smoothly with existing 

practices for issuing airworthiness 

directives. 

In this regard, this final rule is similar 

to SFAR 88, which also required design 

approval holders to perform technical 

evaluations (in that case, of fuel tank 

ignition sources) and to develop 

necessary maintenance actions that 

would be mandated by airworthiness 

directive. To date, the FAA has issued 

over 100 airworthiness directives to 

address unsafe conditions identified as 

a result of SFAR 88. These 

airworthiness directives were issued 

based on this proactive approach of 

requiring analyses to identify unsafe 

conditions, rather than relying on 

service experience to identify them, 

with potentially catastrophic results. In 

the context of SFAR 88, this approach 

has been generally recognized as being 

effective. The objective of this final rule 

is to establish a similar proactive 

approach that will enable us to issue 

any necessary airworthiness directives 

before WFD results in potentially 

catastrophic structural failure. 

c. Costs to Manufacturers 

Airbus indicated that, considering the 

significant number of hours necessary to 

train enough engineers and then to 

comply with the rule, the Initial 

Regulatory Evaluation substantially 

underestimated the costs of this 

rulemaking for manufacturers. Airbus 

said that the cost of future LOV 

extensions should be included. Based 

on further discussion to identify these 

costs, Airbus and the FAA agreed that 

Airbus currently meets the intent of 

today’s rule by performing an evaluation 

of structure susceptible to fatigue and 

establishing an LOV prior to the 

development of WFD. The rule does not 

require manufacturers to extend LOVs— 

thus these extensions are not a 

compliance cost. The FAA does 

understand that LOV extensions are part 

of the existing Airbus business practice. 

Boeing stated that the most significant 

costs will be borne by the manufacturer 

rather than the operator. When the 

manufacturer has to perform additional 

fatigue testing to substantiate an 

operational limit, said the commenter, 

the costs could be quite significant. 

Based on further discussion to identify 

these costs, Boeing and the FAA agreed 

that, because Boeing is also already 

engaged in the activities required by this 

final rule, its additional costs will be 

minimal. 

A later Boeing comment, however, 

said that the regulatory evaluation 

summarized in the Technical 

Document, which was developed by the 

FAA for the public meeting, does not 

identify future expenses the Boeing 

Company will incur. Boeing believes 

this discounting is not correct because 

the company still has substantial work 

to do in providing maintenance 

programs for repairs and alterations, and 

in developing LOVs and supportive 

maintenance actions for postAmendment 25–45 airplanes. Boeing 

said that the costs of an airworthiness 

directive are being attributed to 

operators, but do not account for 

manufacturers’ costs. A second point 

made by this commenter was that 

certain LOVs may be set at a point lower 

than hoped, simply because the 

maintenance actions needed to bring 

that LOV out to a more distant point 

may be too technically difficult and 

costly to perform. This could result in 

a considerable amount of engineering 

work for Boeing to develop the LOV 

that, because the maintenance actions 

are never released, might not result in 

recompense for Boeing. Boeing said that 

we are presenting costs as either 

voluntary compliance for setting LOVs 

or as airworthiness directive costs for 

developing maintenance actions. 

In discussions, Boeing has informed 

us that the company will voluntarily do 

this work to address WFD in its 

airplanes, with or without the rule. As 

a result, the rule does not impose costs, 

and the regulatory evaluation properly 

does not assign costs to Boeing’s 

voluntary compliance. The rule does not 

require that design approval holders 

develop maintenance actions to be 

performed to support the LOV, nor does 

the rule require development of LOVs 

for repairs, alterations, and 

modifications. If the LOV developed by 

the design approval holder does specify 

maintenance actions, the FAA will 

separately estimate the costs of those 


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maintenance actions at the time as part 

of the airworthiness directive notice. 

Any work done on repairs, alterations, 

and modifications, because it is not 

required by the rule, is not accounted 

for as a cost of the rule. Compliance 

costs are assumed to be borne by the 

operators. If manufacturers have 

incurred costs in developing the 

maintenance actions for operators to 

reach LOV, there is nothing that 

precludes them from being 

recompensed for that work. The FAA 

based the analysis of costs in our Initial 

Regulatory Evaluation on discussions 

with the AAWG. Because this final rule 

is significantly different from the 

NPRM, the agency has re-evaluated 

these costs, and the results are reflected 

in the Final Regulatory Evaluation. 

d. Cost of Failing To Harmonize Rule 

Industry representatives on the 

AAWG, Airbus, Boeing, and the ATA 

pointed out that the regulatory 

evaluation did not consider the cost of 

failing to harmonize the rule with other 

airworthiness authorities. Commenters 

suggested that—if the rule were not 

harmonized—there would be a 

substantial negative economic impact 

with respect to the transfer, lease, or 

sales of airplanes between the U.S. and 

other countries. Commenters suggested 

that bilateral agreements be amended to 

support the transfer of used airplanes 

subject to this final rule. 

As discussed in section III.K. above, 

the FAA is working closely with EASA 

and other national airworthiness 

authorities to harmonize this final rule 

as much as possible. Many of the 

changes to the proposed rule will 

facilitate such harmonization. 

e. Cost To Replace an Airplane 

A number of commenters said that the 

initial regulatory evaluation used 

replacement costs that are not accurate 

or justified. According to the ATA, ‘‘The 

assumptions used in the regulatory 

evaluation ignore the reality that some 

airlines replace their fleets with new 

aircraft in most cases, while others 

(particularly cargo carriers) depend on 

used aircraft with long remaining lives 

to support their particular business 

case.’’ In a related vein, Airbus, the 

ATA, and an individual commenter said 

that the regulatory evaluation failed to 

consider the significant cost to operators 

of retiring airplanes. Of particular 

concern was the situation where 

airplanes that support an operation 

reach their operational limit, and there 

are no new airplanes which could fill 

the same role. The ATA said that the 

regulatory evaluation ignores factors 

that operators would take into account 

when deciding whether to retire an 

airplane or to seek approval of an 

extended operational limit but did not 

define those factors. 

In the public meeting on December 

11, 2008, a commenter representing 

United Parcel Service noted that the 

cost benefit analysis was based only on 

Boeing airplanes, and said that if the 

Airbus airplanes were included, there 

would be one airplane model with an 

LOV that is actually less than the design 

service goal in the original NPRM. 

United Parcel Service commented that 

operators of those airplanes would be 

interested in understanding how that 

economic impact to the residual value 

of those airplanes was not included in 

the cost. United Parcel Service also 

asked, since Boeing had expressed 

discomfort with the use of the 

anticipated LOV information that it had 

originally given the FAA, how the FAA 

could be comfortable using that 

information for the regulatory 

evaluation. Since the public meeting, 

Boeing has provided updated 

information about anticipated LOVs for 

their airplanes. Airbus has provided a 

table containing updated information on 

certain Airbus model LOVs and 

anticipated extensions to LOVs. The 

FAA uses this updated information in 

the Final Regulatory Evaluation. 

Lynden Air Cargo said that the initial 

regulatory evaluation did not provide a 

true economic impact for either design 

approval holders or operators because it 

is based upon unknown facts from too 

few design approval holders and with 

no input from operators, who will bear 

90% of the costs. Lynden Air Cargo 

provided flight cycle and flight hour 

data for its L–382G airplanes. Based on 

an LOV of 75,000 flight hours, Lynden 

Air Cargo stated that issuance of the 

‘‘anticipated LOVs,’’ which are included 

in the Technical Document, would 

require that Lynden Air Cargo 

immediately retire three of its six 

airplanes and, at the Lynden Air Cargo 

current utilization rate, retire the other 

three by approximately December 2019. 

Lynden Air Cargo estimates the cost to 

replace its six airplanes would range 

from $120 million to $810 million, if 

comparable airplanes were available. 

Lockheed indicated that the LOV 

anticipated for the L–382 would be 

based only on flight hours. Based on 

flight hours, usage, and current 

ownership, we do not estimate that any 

L–382 airplanes will be retired in our 

20-year analysis period. Lockheed stated 

that it will continue to support the L– 

382 model regardless of whether the 

FAA issues a WFD rule. 

In developing the Final Regulatory 

Evaluation, the FAA used a commercial 

fleet data product that identifies the 

status of airplane hours and cycles. The 

FAA found only one U.S.-registered 

airplane currently operating under part 

121 with a number of flight cycles 

exceeding the anticipated LOV for the 

airplane and only five U.S.-registered 

airplanes operating under part 121 that 

exceed 80% of those LOVs. 

The economic cost of requiring 

retirement of an airplane at the 

anticipated LOV is a central issue in the 

cost estimate for today’s rule. Common 

business practice is to value assets at the 

current market value, and the FAA 

follows this practice in the Final 

Regulatory Evaluation. In the case of 

airplanes at or near the end of their 

commercial lives, this value is quite 

small. Assigning a cost of purchasing a 

new airplane to replace an airplane at 

LOV would be a serious overstatement 

because it ignores the decline in value 

as airplanes age. 

f. Residual Value of Airplanes 

Several commenters, including the 

ATA, FedEx, United Parcel Service, 

Airbus, the CAA, Technical Data 

Analysis, Inc., and Celeris Aerospace of 

Canada, stated that the initial regulatory 

evaluation did not consider the impact 

of the proposal on loans, leases, and 

residual value of airplanes. They said 

the rule would have a particularly 

significant effect on cargo operations, 

which tend to use older airplanes. 

These comments are based on an 

assumption that LOVs will be 

established at levels below where 

significant numbers of airplanes would 

otherwise be retired. 

As discussed previously, the vast 

majority of airplanes are currently 

retired well before the LOVs that design 

approval holders anticipate establishing 

under this final rule. These retirements 

are for economic reasons unrelated to 

today’s rule. The FAA expects that 

future retirement decisions will be made 

for similar reasons and that this final 

rule will force retirement of only one 

airplane that is otherwise reaching the 

end of its commercial operational life. 

We use an appraiser-estimated 

airplane value when the airplane 

reaches LOV before retirement. This 

estimate properly reflects the true value 

of the asset. To include any other cost 

estimate would be double counting. 

3. ‘‘Rotable’’ Parts 

Northwest Airlines commented that it 

is not clear whether or not airplane life 

limits (the commenter’s term for LOVs) 

extend to components, such as engine 

nacelles, passenger and cargo doors, 

flight controls, and wing-to-body 

fairings. These components can be 


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‘‘swapped out,’’ or rotated (they’re 

known in the industry as rotable parts) 

from one airplane to another. Northwest 

Airlines said that there is a potential for 

significant costs associated with rotable 

parts if they are limited by an airplane’s 

LOV. Operators typically do not track 

the number of accumulated flight cycles 

or flight hours for them. Northwest 

Airlines stated that operators may have 

to assume the flight cycles or flight 

hours on affected rotable parts to be 

equal to the world high-time airplane 

for that model. This may require that 

operators ground many airplanes or 

scrap rotable parts, resulting in 

significant costs that have not been 

captured in the regulatory evaluation 

included in the Technical Document. 

The LOV is an airplane-level number. 

The FAA does not anticipate that 

rotable parts will be identified by design 

approval holders as structure 

susceptible to WFD. This is because the 

parts typically considered as rotable do 

not have structural details and elements 

that are repeated over large areas and 

operate at the same stress levels. AC 

120–YY provides examples of structure 

in which multiple site damage or 

multiple element damage could occur. 

Rotable parts are not included in those 

examples. As a result, we have 

determined that rotable parts do not 

affect the cost of this final rule. 

4. Use of LOVs for Financial Evaluations 

Airbus expressed concerns similar to 

those expressed by Boeing and the 

members of AAWG about lack of 

uniformity in the manner in which 

various manufacturers are setting LOVs. 

The commenter also stated that it was 

important that the LOVs, and the LOV 

flight hour or flight cycle numbers, not 

be used by non-technical people in the 

finance community to set depreciation 

schedules, commercial valuations, 

comparisons, and competitive 

arguments. Airbus was concerned that 

such use of non-standardized data could 

lead to market distortion. 

Airbus requested that we not publish 

LOV tables for each manufacturer’s 

product lines in the rule and its 

preamble. It stated that this information 

would much more appropriately be 

published and updated in the 

manufacturer’s Instructions for 

Continued Airworthiness for each 

airplane. Airbus suggested that, if the 

FAA nevertheless decides that 

publishing such LOV tables is 

necessary, then it would be important to 

develop, in concert with industry, the 

definitions, criteria, and methodologies 

to be used, so that resulting LOVs from 

all sources are consistent. 

The FAA has revised the rule to 

ensure that there is an objective, 

performance-based standard for 

developing LOVs, and AC 120–YY has 

been updated to provide guidance in 

complying with those standards. The 

reason that design approval holders may 

appear to be arriving at different LOV 

numbers is largely a function of the age 

of their respective fleets. A design 

approval holder whose fleet is older will 

have a much larger body of service 

experience on which to confidently base 

an LOV. A design approval holder with 

a younger fleet might be more 

conservative when first setting an LOV, 

because there is not as much service 

experience data on which to base it. 

Another factor affecting how a design 

approval holder goes about setting an 

LOV is how much fatigue testing has 

been performed on a particular model. 

The FAA appreciates that Airbus 

supports the intent of the WFD 

rulemaking, and understands Airbus’ 

concern that LOVs could be 

misinterpreted by those who ‘‘set or 

approve’’ the economic life of an 

airplane. The FAA does not expect, nor 

intend, the LOV in the WFD final rule 

to set the economic life of an airplane. 

The March 18, 2009 edition of Aviation 

Daily reported that Airbus has extended 

the service goals of the A330–200 and 

A340–200 and –300. The purpose of 

publishing manufacturers’ LOVs in the 

regulatory evaluation appendix is to 

provide clarity, transparency, and 

reproducibility for the economic 

analysis. As Airbus requested, the 

reason for the publication of LOVs is 

clarified in the Final Regulatory 

Evaluation. In the regulatory evaluation, 

the FAA states that it is important to 

note that manufacturers have changed 

LOVs based on updated information. 

Airbus, for instance, sets an initial LOV 

as a declared point for certification 

purposes. Periodically, as airplanes are 

shown to be viable for longer lives, 

design approval holders put programs in 

place to extend LOVs well before those 

utilizations are achieved. The FAA 

believes that manufacturers will 

continue this practice into the future 

and update their airplanes’ LOVs. Thus 

the LOVs used in this regulatory 

evaluation should not be used as a basis 

for setting the economic life of an 

airplane. Based upon history, our 

estimated costs, which were based upon 

the current LOVs, may be overstated. 

IV. Regulatory Notices and Analyses 

Paperwork Reduction Act 

The Paperwork Reduction Act of 1995 

(44 U.S.C. 3507(d)) requires that the 

FAA consider the impact of paperwork 

and other information collection 

burdens imposed on the public. 

According to the 1995 amendments to 

the Paperwork Reduction Act (5 CFR 

1320.8(b)(2)(vi)), an agency may not 

collect or sponsor the collection of 

information, nor may it impose an 

information collection requirement, 

unless it displays a currently valid 

Office of Management and Budget 

(OMB) control number. 

This final rule will impose the 

following new information collection 

requirements. As required by the 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3507(d)), the FAA has submitted 

these information collection 

amendments to OMB for its review. The 

Office of Management and Budget 

approved these new information 

collection requirements associated with 

this final rule and assigned OMB 

Control Number 2120–0743. 

Title: Widespread Fatigue Damage. 

Summary: Today’s rule consists of 

regulatory changes pertaining to 

widespread fatigue damage in transport 

category airplanes. Some of these 

changes require new information 

collection. The new information 

requirements and the persons required 

to provide that information are 

described below. 

(1) Amendment of part 26 requires 

that holders of design approvals for 

certain existing transport category 

airplanes establish limits of validity 

(operational limits) for those airplanes. 

Those design approval holders are also 

required to revise the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness (ICA) to 

include the LOV. 

(2) Amendment of part 26 also 

requires that design approval holders 

submit to the FAA a plan detailing how 

they intend to comply with the new 

requirements. The compliance plan 

ensures that design approval holders 

fully understand the requirements, 

correct any deficiencies in planning in 

a timely manner, and provide the 

information needed by the operators for 

timely compliance with the rule. 

(3) Any person operating an airplane 

under part 121 or 129 is required to 

revise its maintenance program to 

incorporate an Airworthiness 

Limitations section that includes an 

LOV. Operators would be prohibited 

from operating an airplane past that 

limit. 

(4) As an option, any person may 

apply for an extended LOV for affected 

airplanes. This option has requirements 

similar to those imposed on design 

approval holders for establishing an 

initial LOV. There may be service 

information developed that would 


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support the extended limit and would 

be documented as airworthiness 

limitation items. To operate beyond the 

initial LOV, an operator would have to 

incorporate the extended limit and any 

airworthiness limitation items 

pertaining to widespread fatigue damage 

into its maintenance program. 

Use of Collected Information: These 

requirements support the information 

needs of the FAA in finding compliance 

with the rule by design approval holders 

and operators. 

Average Annual Burden Estimate: 

The burden would consist of the work 

necessary to: 

• Develop or revise the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness to include 

the LOV. 

• Develop the compliance plan. 

• Incorporate the new information 

into the operator’s maintenance 

program. 

Today’s rule results in the following 

annual recordkeeping and reporting 

burden: 

FIGURE 4—RECORDKEEPING AND REPORTING FOR THIS RULE

Documents required to show compliance with the proposed rule Total labor 

hours 

Total average 

annual hours 

Present value 

discounted 

($2010) cost 

FAA-approved revised or new ALS ............................................................................................. 660 132 $41,674 

FAA-approved WFD compliance plan ......................................................................................... 435 * 435 33,418 

FAA-approved maintenance program revision for operators ...................................................... 210 35 12,846 

Total ...................................................................................................................................... 1,305 602 87,938 

* This one-time burden will occur in the first 90 days of the compliance period. 

The FAA computed the annual 

recordkeeping burden (in total hours) by 

analyzing the paperwork needed to 

satisfy each requirement of the rule. The 

average cost per hour varies with the 

number of affected airplanes in each 

group, the amount of engineering time 

required to develop the LOV, and the 

amount of time required for revising the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness. Other costs associated 

with the information collection 

requirements within this rule (in 

addition to the monetized hourly costs 

reflected above) are minimal. 

In addition to the requirements 

outlined above, future applicants for 

either supplemental type certificates or 

amendments to type certificates that 

decrease or increase maximum takeoff 

gross weights would be required to 

develop a compliance plan for the 

certification project. The Paperwork 

Reduction Act compliance for 

development of these certification plans 

is covered by a previously approved 

collection (OMB Control Number 2120– 

0018) associated with part 21. We 

estimate the additional burden to 

include information on a plan for 

establishing an LOV for these airplanes 

would be minimal. 

International Compatibility 

In keeping with U.S. obligations 

under the Convention on International 

Civil Aviation, it is FAA policy to 

comply with International Civil 

Aviation Organization (ICAO) Standards 

and Recommended Practices to the 

maximum extent practicable. The FAA 

has determined that there are no ICAO 

Standards and Recommended Practices 

that correspond to these regulations. 

Economic Assessment, Regulatory 

Flexibility Determination, Trade Impact 

Assessment, and Unfunded Mandates 

Assessment 

This portion of the preamble 

summarizes the FAA’s analysis of the 

economic impacts of this Final Rule. It 

also includes the final regulatory 

flexibility determination, the 

international trade impact assessment, 

and the unfunded mandates assessment. 

The FAA suggests readers seeking 

greater detail read the full regulatory 

evaluation, a copy of which has been 

placed in the docket for this rulemaking. 

Changes to Federal regulations must 

undergo several economic analyses. 

First, Executive Order 12866 directs that 

each Federal agency shall propose or 

adopt a regulation only upon a reasoned 

determination that the benefits of the 

intended regulation justify its costs. 

Second, the Regulatory Flexibility Act 

of 1980 requires agencies to analyze the 

economic impact of regulatory changes 

on small entities. Third, the Trade 

Agreements Act (19 U.S.C. 2531–2533) 

prohibits agencies from setting 

standards that create unnecessary 

obstacles to the foreign commerce of the 

United States. In developing U.S. 

standards, this Trade Act requires 

agencies to consider international 

standards and, where appropriate, to be 

the basis of U.S. standards. Fourth, the 

Unfunded Mandates Reform Act of 1995 

(Pub. L. 104–4) requires agencies to 

prepare a written assessment of the 

costs, benefits, and other effects of 

proposed or final rules that include a 

Federal mandate likely to result in the 

expenditure by State, local, or Tribal 

governments, in the aggregate, or by the 

private sector, of $100 million or more 

annually (adjusted for inflation). 

In conducting these analyses, FAA 

has determined this final rule has 

benefits that justify its costs, and is a 

‘‘significant regulatory action’’ as 

defined in section 3(f) of Executive 

Order 12866 because it raises novel 

policy issues contemplated under that 

executive order. The rule is also 

‘‘significant’’ as defined in DOT’s 

Regulatory Policies and Procedures. The 

final rule, if adopted, however, will not 

have a significant economic impact on 

a substantial number of small entities, 

will not create unnecessary obstacles to 

international trade and will not impose 

an unfunded mandate on State, local, or 

Tribal governments, or on the private 

sector. These analyses, available in the 

docket, are summarized below. 

Total Costs and Benefits of This 

Rulemaking 

The overriding safety concern of 

today’s rule is WFD-related incidents 

and accidents that have occurred and 

the continuing discoveries of WFD 

problems in the fleet. The current 

approach does not always find WFD 

before in-flight events occur. Today’s 

rule will establish the necessary steps to 

prevent WFD in the future by requiring 

that design approval holders establish 

LOVs. 

With this final rule, design approval 

holders may continue their work to 

provide maintenance actions that 

support the safe operation of airplanes 

up to LOV. The FAA would proactively 

issue airworthiness directives 

mandating those planned maintenance 

actions rather than reactively issuing 

emergency airworthiness directives and 

immediately adopted rules which 


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49Maintenance actions include inspections, 

modifications, and replacements. Because the 

extended LOV is not required, operators would 

have to decide to retire airplanes or perform the 

maintenance actions with the extended LOV. 50These ADs would be issued eventually, even 

without this rule, because WFD is inevitable and is 

an unsafe condition. More ADs may need to be 

written without this rule. If the necessary service 

information is not developed until after a finding 

of WFD in service, the resulting ADs are likely to 

include interim action requirements and have 

shorter compliance times, as compared with ADs 

issued based on service information developed as 

required by this rule. 

require unanticipated inspections and 

repairs. The FAA estimates that this 

approach is worth $4.8 million in 

present value. 

In contrast to the NPRM, the final rule 

total costs are minor. Several significant 

factors are responsible for the reduction 

in these costs. First, the final rule does 

not include the repair, alterations, and 

modification requirement as in the 

NPRM. Second, many older airplanes 

have been retired since the NPRM. 

Third, due to the comments and 

conversations with design approval 

holders, the agency now understands 

that most LOVs will be set 33% to 180% 

higher than design service goal rather 

than at design service goal as was 

specified in the NPRM. Because of 

current maintenance programs and 

voluntary compliance by design 

approval holders, costs for design 

approval holders and operators are 

expected to be minimal. We anticipate 

that today’s rule will result in one 

airplane retiring sooner than the 

operator would like, in contrast to the 

NPRM which predicted that many 

airplanes would retire sooner. Thus our 

base case model attributes the cost of 

this rule to the retirement of that one 

airplane, because it will reach the 

anticipated LOV within the 20-year 

analysis period. This will result in costs 

of $3.8 million, with a present value of 

$3.6 million. 

Thus, as noted earlier, this final rule’s 

expected present-value benefits of $4.8 

million exceed the expected presentvalue costs of $3.6 million. 

FIGURE 5—COMPARISON OF COST ASSUMPTIONS FOR NPRM AND FINAL RULE

NPRM assumptions 

NPRM present 

value costs 

($ millions) 

Final rule assumptions 

Final rule 

present 

value costs 

($ millions) 

Operator Retirement Costs .................................................. 160 Operator Retirement Costs ................................... 3.6 

• Initial Operational Limit (IOL) = Design Service Goal 

(DSG). 

• Limit of validity (LOV) > DSG for many models.

• 27 airplanes would be retired in the first year of 

compliance. 

• 1 airplane would be retired in the 20-year 

analysis period.

• Some IOL extensions. • Few LOV extensions.

Operator Maintenance Program Costs ................................ 164 Operator Maintenance Program Costs ................. 0 

• WFD maintenance actions 49 were included with extended operational limits.• With higher LOV, WFD maintenance actions 

may be necessary and would be mandated by 

ADs, per existing practice.50

• We assumed some operators would perform maintenance actions. • Operators’ costs to perform maintenance actions are included in cost of ADs.

Design Approval Holder (DAH) Costs ................................. 36 DAH Costs ............................................................ 0 

Assumed 10% of entire costs. Assumed minimal costs because DAHs are 

voluntarily developing LOVs and maintenance 

actions.

Total Costs ............................................................. 360 Total Costs ........................................................ 3.6 

Who is potentially affected by this 

rulemaking? 

• Design approval holders of 

transport category airplanes with a 

maximum takeoff gross weight greater 

than 75,000 pounds. 

• Applicants for type certificates of 

transport category airplanes with a 

maximum takeoff gross weight greater 

than 75,000 pounds, if the date of 

application was before the effective date 

of the rule. 

• Applicants for amendments to type 

certificates of transport category 

airplanes with a maximum takeoff gross 

weight greater than 75,000 pounds, with 

the exception of those that change the 

maximum takeoff gross weight of the 

airplane. 

• Applicants or design approval 

holders for either supplemental type 

certificates or amendments to type 

certificates that increase maximum 

takeoff gross weights from 75,000 

pounds or less to greater than 75,000 

pounds. 

• Applicants or design approval 

holders for either supplemental type 

certificates or amendments to type 

certificates that decrease maximum 

takeoff gross weight from greater than 

75,000 pounds to 75,000 pounds or less 

after the effective date of the rule. 

• Applicants for future type 

certificates, or for either supplemental 

type certificates or amendments to 

future type certificates, for all transport 

category airplanes, after the effective 

date of the rule. 

• U.S. certificate holders and foreign 

air carriers and foreign persons 

operating U.S.-registered transport 

category airplanes under 14 CFR part 

121 or 129 with a maximum takeoff 

gross weight greater than 75,000 

pounds. 

• Operators of any transport category 

airplanes certified in the future, 

regardless of maximum takeoff gross 

weight, if the date of application was 

after the effective date of the rule. 

Our Cost Assumptions and Sources of 

Information 

• Discount rate = 7%. 

• Period of Analysis = 20 years. 

• Value of fatality averted = $5.8 

million (Source: U.S. Department of 

Transportation, Treatment of Value of 

Life and Injuries in Preparing Economic 

Evaluations, February 8, 2008). 

• Aircraft Values = 2009 Avitas Blue 

Book of Jet Aircraft/Industry 

Consultation. 

• Aircraft Fleet Data = OAG 

Associates Fleet Database. 

Alternatives Considered 

The FAA considered four alternatives 

to the proposed rule. These were: 

1. Exclude small entities. 

2. Extend the compliance deadline for 

small entities. 


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3. Establish lesser technical 

requirements for small entities. 

4. Expand the requirements To cover 

more airplanes. 

1. Exclude Small Entities 

The FAA concluded that excluding 

small entities from all the requirements 

of the proposed rule was not justified. 

The purpose of the proposed rule is to 

maintain the airworthy operating 

condition of airplanes regardless of 

secondary considerations. 

2. Extend the Compliance Deadline for 

Small Entities 

The FAA also considered options that 

would lengthen the compliance period 

for small operators. The FAA believes 

time extensions only provide modest 

cost savings and leave the system safety 

at risk. 

3. Establish Lesser Technical 

Requirements for Small Entities 

The FAA considered establishing 

lesser technical requirements for small 

entities. However, the FAA believes the 

risks are similarly unreasonable for 

small entities operating airplanes 

susceptible to WFD, and that the 

benefits of including small entities 

justify the cost. 

4. Expand the Requirements To Cover 

More Airplanes 

The FAA considered requiring all 

operators of existing transport category 

airplanes to comply with the proposed 

rule. However, the overwhelming 

majority of passengers and cargo are 

carried by airplanes with a maximum 

gross takeoff weight of greater than 

75,000 pounds. The 75,000 pound 

weight cutoff was based on 

recommendations from the AAWG for 

WFD rulemaking. Because of this, the 

FAA decided to restrict compliance to 

operators of those airplanes. 

The FAA concludes the current rule 

is the preferred alternative because it 

has benefits exceeding compliance costs 

and allows for continued operation of 

certain airplanes only up to the point 

where existing maintenance actions can 

no longer ensure that the airplanes are 

free from WFD. 

Benefits of This Rulemaking 

The non-quantified benefits include 

the safe (from WFD) operation of 

airplanes up to the LOV. 

The lower-bound present value 

benefits of this final rule (the minimum 

value of a range estimate of benefits) are 

$4.8 million in present value. These 

quantified benefits are based on the near 

elimination of emergency airworthiness 

directives. 

Costs of This Rulemaking 

The total incremental costs of this 

final rule are approximately $3.6 

million in present value from the costs 

of retiring one airplane. 

Final Regulatory Flexibility Analysis 

Introduction and Purpose of This 

Analysis 

The Regulatory Flexibility Act of 1980 

(Pub. L. 96–354) (RFA) establishes ‘‘as a 

principle of regulatory issuance that 

agencies shall endeavor, consistent with 

the objectives of the rule and of 

applicable statutes, to fit regulatory and 

informational requirements to the scale 

of the businesses, organizations, and 

governmental jurisdictions subject to 

regulation. To achieve this principle, 

agencies are required to solicit and 

consider flexible regulatory proposals 

and to explain the rationale for their 

actions to assure that such proposals are 

given serious consideration.’’ The RFA 

covers a wide range of small entities, 

including small businesses, not-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. 

The FAA considers that this final rule 

will not result in a significant economic 

impact on a substantial number of small 

entities. The purpose of this analysis is 

to provide the reasoning underlying the 

FAA determination. 

First, we will discuss the reasons why 

the FAA is considering this action. We 

will follow with a discussion of the 

objective of, and legal basis for, the final 

rule. Next, we explain there are no 

relevant Federal rules which may 

overlap, duplicate, or conflict with the 

final rule. Then we will discuss the 

substantial changes from the proposed 

to the final rule. Next, we will discuss 

the comments received about the Initial 

Regulatory Flexibility Analysis (IRFA). 

Lastly, we will describe and provide an 

estimate of the number of small entities 

affected by the final rule and why the 

FAA considers that this final rule will 

not result in a significant economic 

impact on a substantial number of small 

entities. 

We now discuss the reasons why the 

FAA is considering this action. 

The FAA is issuing this final rule to 

address the structural problems of aging 

airplanes known as ‘‘widespread fatigue 

damage’’ (WFD). WFD is characterized 

by the simultaneous presence of cracks 

at multiple structural locations that are 

of sufficient size and density that the 

structure will no longer meet its 

residual strength requirement and could 

catastrophically fail. 

Past examples of WFD occurring in 

the fleet include: 

• The 1988 Aloha 737 accident, 

• An in-flight Lockheed Model L– 

1011 failure of aft pressure bulkhead 

stringer attach fittings, 

• A McDonnell Douglas Model DC–9 

aft pressure bulkhead cracks, 

• Boeing Models 727 and 737 lap 

splice cracking, 

• Boeing Model 767 aft pressure 

bulkhead cracking, and 

• Boeing Model 747 and Airbus A300 

frame cracking. 

Because of these past incidents, 

accidents, and inspection discoveries 

and others, the FAA has already issued 

about 100 WFD-related airworthiness 

directives. 

This final rule is being promulgated 

because the FAA believes the risk of an 

accident caused by WFD, and the 

potential collateral damage after such an 

accident, is too high without 

implementing today’s rule. 

We now discuss the objective of, and 

legal basis for, the final rule. Next, we 

discuss if there are relevant Federal 

rules which may overlap, duplicate, or 

conflict with the final rule. 

Title 49 of the United States Code 

requires the FAA Administrator to 

consider the following authority: 

• Assigning, maintaining, and 

enhancing safety and security as the 

highest priorities in air commerce. (49 

U.S.C. 40101(d)(1). 

• Aging Airplane Safety Act of 1991. 

(49 U.S.C. 44717). 

• The FAA Administrator’s statutory 

duty to carry out his or her 

responsibilities ‘‘in a way that best tends 

to reduce or eliminate the possibility or 

recurrence of accidents in air 

transportation.’’ (See 49 U.S.C. 

44701(c)). 

Therefore, this final rule will amend 

Title 14 of the Code of Federal 

Regulations to require existing design 

approval holders to establish LOVs and 

operators of any affected airplane to 

incorporate those LOVs into 

maintenance programs of large transport 


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51 13 CFR 121.201, Size Standards Used to Define 

Small Business Concerns, Sector 48–49 

Transportation, Subsector 481 Air Transportation. 

category airplanes with a maximum 

takeoff gross weight greater than 75,000 

pounds, operating under 14 CFR part 

121 and 129. These requirements will 

also apply to all applicants for type 

certificates after the effective date of the 

rule and operators of those airplanes. 

Today’s rule does not require that any 

maintenance actions be performed to 

prevent WFD before an airplane reaches 

its LOV. Any maintenance actions 

necessary to reach the LOV will be 

mandated by airworthiness directives 

through separate rulemaking actions, so 

their costs are not attributable to this 

final rule. 

This final rule will not overlap, 

duplicate, or conflict with existing 

Federal Rules. 

We now discuss the changes from the 

proposed to the final rule and the reason 

the small entity determination in the 

Final Regulatory Flexibility Analysis 

(FRFA) has changed. 

The FAA has made substantial 

changes to the WFD NPRM that 

significantly reduces costs to both small 

and large business entities. We have 

eliminated the requirement to evaluate 

WFD associated with repairs, 

alterations, and modifications of the 

baseline airplane structure, except for 

those mandated by airworthiness 

directives. This change dramatically 

reduces the economic impact of the 

NPRM’s estimated compliance costs to 

small entity operators of part 25 

airplanes. Also, in our request for 

comments, design approval holders 

responded by providing estimates of 

LOVs for their affected airplanes. In the 

NPRM we assumed the LOV will occur 

at an airplane’s design service goal. 

Based on design approval holder 

comments LOV, in many cases, occurs 

anywhere from 33% to 180% beyond 

the design service goal, depending on 

the equipment model. An operator can 

now operate an airplane well past its 

design service goal and not incur the 

costs of making the decision to retire or 

extend the affected airplane’s LOV until 

much later in the airplane’s life. The 

only remaining cost is that we assume 

operators will retire their airplanes at 

LOV, rather than incurring the cost of 

the additional maintenance actions that 

may be needed for an extended LOV. 

With the scope of the rule reduced, both 

in terms of required inspections and in 

terms of affected airplanes, the 

economic costs of this final rule are 

much lower than the costs estimated in 

the NPRM and in the initial regulatory 

evaluation. 

The FAA will now discuss the one 

comment received about the Initial 

Regulatory Flexibility Analysis (IRFA). 

In the responses to the IRFA of the 

NPRM, we received a comment from 

Lynden Air Cargo. Lynden stated its 

L–382G airplanes were not included in 

IRFA. The commenter is correct. The 

Fleet data services consulted for the 

initial regulatory evaluation did not 

carry flight utilization data for L–382Gs, 

and the FAA was unable to determine 

the number of accumulated flight cycles 

or flight hours of Lynden’s fleet in 

comparison to the anticipated LOV for 

those airplanes. Because of the lack of 

utilization data, Lynden’s fleet was not 

included in our sample for the IRFA 

analysis. Lynden Air Cargo has since 

provided the FAA with utilization 

information for its L–382G fleet. 

Lockheed has provided an updated 

anticipated LOV for the L–382G fleet, 

based just in hours, and Lynden’s entire 

fleet is below 80% of the LOV. With the 

base hours less than 80% of LOV, and 

with the current utilization rates of 

these airplanes, they will not reach LOV 

in the 20-year analysis time frame. 

Therefore the FAA expects no economic 

impact to Lynden Air Cargo in the 

analysis period for the final rule. 

The FAA will now discuss the 

methodology used to determine the 

number of small entities for which the 

final rule will apply. The FAA will also 

discuss why the agency considers that 

this final rule will not result in a 

significant economic impact on 

manufacturers of part 25 airplanes. 

For aircraft operators and 

manufacturers, a small entity is defined 

as one with 1,500 or fewer employees.51

Since there are operators that met those 

criteria, the FAA conducted an 

economic impact assessment to 

determine if the rule will have a 

significant economic impact on a 

substantial number of these operators. 

This final rule will become fully 

effective in 2010. Although the FAA 

forecasts traffic and air carrier fleets to 

2030, too many factors are in play to 

estimate a future number of small 

entities, determine if an operator will 

still be in business, or determine 

whether that operator will still remain 

a small business entity. Therefore the 

agency will use the current U.S. 

operator’s fleet and employment in 

order to determine the number and 

impact on small business entities this 

final rule will affect. 

For analysis purposes, the FAA has 

divided the small entities that might be 

impacted by this final rule into two 

major classes, airplane manufacturers 

and air carriers. 

Currently, U.S. part 25 aircraft 

manufacturer type certificate holders 

include the following: 

• The Boeing Company. 

• Cessna Aircraft Company (a 

subsidiary of Textron Inc.). 

• Raytheon Company. 

• Gulfstream Aerospace Corporation 

(a wholly owned subsidiary of General 

Dynamics). 

All United States part 25 aircraft 

manufacturers exceed the Small 

Business Administration small-entity 

criteria of 1,500 employees for aircraft 

manufacturers. 

Air carriers potentially affected by the 

final rule include operators engaged in 

the following: 

• Scheduled air transportation. 

• Air courier service. 

• Nonscheduled air transportation. 

The FAA obtained the number of 

U.S.-operated airplanes having a 

maximum takeoff gross weight greater 

than 75,000 pounds from the OAG 

Associates Fleet Database (March 2009). 

This database identifies U.S. operators 

of affected airplanes by providing 

airplane age and flight utilization 

statistics. The FAA used the airplane 

flight utilization information in the 

analysis of small entity operator’s 

airplanes affected by this WFD final 

rule. The FAA obtained annual 

operators’ revenue and employment 

data from current public filings, the 

World Aviation Directory, and U.S. DOT 

Form 41 schedules. 

Companies with greater than 1,500 

employees were excluded from further 

analysis. Operators in Chapter XI 

bankruptcy were also excluded, since 

the outcomes of such proceedings are 

unknown. Lastly, we excluded all part 

25 turbine-powered airplanes with a 

maximum takeoff gross weight of 75,000 

pounds or less, or with a type certificate 

issued before January 1, 1958, because 

these airplanes are not affected by the 

final rule. 

This procedure resulted in a list of 

airplanes, operated by U.S. operators 

with less than 1,500 employees, with a 

gross takeoff weight greater than 75,000 

pounds. To this database were added 

airplane-specific design service goals, 

LOVs, and airplane residual value 

fields. The FAA used the design service 

goals published in the WFD NPRM and 

later updated them based on FAA and 

industry input. Manufacturers provided 

the LOVs. Airplane residual values were 

obtained from the 2009 Avitas Bluebook 

of Jet Aircraft and consultations with 

industry. 

Next follows the discussion of the 

number of small entity operators with 

airplanes affected by the rule, and how 


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much it will cost for them to be in 

compliance. 

Today’s rule may cause airplanes to 

be retired, sold, or replaced sooner than 

an operator would like. Companies 

make decisions on the retirement, sale, 

or replacement of airplanes for many 

reasons. The decision point to sell, 

retire, or replace an airplane differs 

across companies. Operators take into 

account several key factors in their 

decision on when to retire an aircraft. 

The following are some of those key 

factors: 

• Maintenance costs. 

• Noise levels. 

• Fuel consumption. 

• Loss of consumer demand. 

• Regulation changes. 

• Shifting operator business plans. 

• Operating costs. 

Therefore, a company generally 

decides to retire, sell, or replace an 

airplane long before its LOV is reached. 

Given current airplane utilization rates, 

the FAA does not expect the final rule 

to affect companies below 75% of an 

airplane’s LOV. When an airplane’s 

flight utilization (measured in flight 

cycles or hours) exceeds 75% of LOV, 

the expectation is that the WFD 

provisions will become an increasingly 

important component of the decision to 

retire the airplane. All U.S. airplanes 

over 75% LOV currently operated by 

small business entities are in nonscheduled service. Many of these 

affected airplanes are being operated by 

cargo operators and hence have a lower 

utilization rate than their counterparts 

in scheduled passenger service. 

The FAA discovered that 21 airplanes 

being operated by eight small entities 

were over 75% of LOV. For the 21 

affected airplanes over 75% of LOV, the 

FAA analyzed utilization history reports 

by serial number. Results of this 

analysis showed that saying that 21 

airplanes are over 75% of their LOVs 

overstates the number of airplanes 

affected by this final rule, because some 

of those airplanes listed as active have 

not accrued utilization statistics for 

years. The agency has identified 9 out 

of the 21 affected airplanes that have not 

accrued utilization for the past two 

years or longer. If the airplanes are not 

accumulating flight cycles or hours for 

years, then given the age of these 

airplanes, the FAA assumes that these 

airplanes are parked or retired. 

This final rule will impose either the 

retirement of an airplane at LOV or a set 

of maintenance changes to extend the 

LOV for the airplane. In this final 

regulatory analysis, the assumption is 

that operators will retire the airplanes at 

LOV. The airplane retirement cost is the 

operator’s most expensive economic 

choice based on compliance with the 

final rule. 

The FAA’s analysis determined that 

no small entities currently operate 

airplanes over 100% of LOV. 

One small entity currently operates 

one airplane between 90–100% of LOV. 

Four small entities currently operate 

four airplanes between 80–90% of LOV. 

Lastly, the database lists four small 

entities operating seven airplanes 

between 75–80% of LOV. Table 1 shows 

these results: 

To estimate when an airplane will 

exceed LOV, the FAA followed these 

steps: From the March 2009 OAG 

Associates Fleet database the FAA 

calculated the average age of U.S.- 

operated part 25 transport category 

retired airplanes over time. OAG defines 

a retired airplane as one that has been 

retired, scrapped or otherwise destroyed 

by its owner/operator at the end of the 

airplane’s useful life. The FAA 

calculated the average age based upon 

the retired airplanes in the OAG fleet 

database beginning in the 1940s. On 

average, part 25 passenger airplanes 

were operated for 25 years and cargo 

airplanes were operated for 34 years, 

and then retired from U.S. service. 

For the base case in the regulatory 

evaluation, the FAA assumed that in 

year 25 of operation, every affected 

passenger airplane will convert to cargo 

service and then retire from cargo 

service at 34 years. The FAA chose this 

scenario for the cost model because it 

captures nearly all of the affected 

airplanes. 

The FAA applied these average ages 

to the affected airplanes in Table 1 and 

retired airplanes over the average 

retirement age of 34 years over the 

20-year analysis interval used in the 

regulatory evaluation. Under this model, 

the agency assumes retirement of only 

one Boeing 747 airplane operated by a 

small business entity, because that 

airplane will reach its LOV before 

reaching its average retirement age. 

The model estimates one small 

business entity will retire one airplane 

soon after the rule is promulgated. This 

small business entity will need to 

implement an appropriate WFD 

program, and either apply for an 

extended LOV or retire the airplane. For 

the FRFA, the FAA assumed the 

affected small entity will retire the 

airplane. 

The FAA estimated the final rule’s 

present value costs to the air carrier 

based on the 2009 Avitas Bluebook of 

Jet Aircraft residual value of the 

airplane forced to retire. The presentvalue residual value of the affected 

airplane is $3.6 million. The ratio of this 

present value cost to annual revenues is 

1.28%. The FAA does not consider this 

impact to be economically significant, 

and since only one entity is potentially 

affected, this is not a substantial number 

of small entities. 

The FAA Administrator certifies that 

this rule will not have a significant 

economic impact on a substantial 

number of small entities. 

International Trade Impact Analysis 

The Trade Agreements Act of 1979 

(Pub. L. 96–39), as amended by the 

Uruguay Round Agreements Act (Pub. 

L. 103–465), prohibits Federal agencies 

from establishing standards or engaging 


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in related activities that create 

unnecessary obstacles to the foreign 

commerce of the United States. 

Pursuant to these Acts, the 

establishment of standards is not 

considered an unnecessary obstacle to 

the foreign commerce of the United 

States, so long as the standard has a 

legitimate domestic objective, such as 

the protection of safety, and does not 

operate in a manner that excludes 

imports that meet this objective. The 

statute also requires consideration of 

international standards and, where 

appropriate, that they be the basis for 

United States standards. The FAA has 

assessed the potential effect of this final 

rule and determined that it will impose 

the same costs on domestic and 

international entities and thus has a 

neutral trade impact. 

Unfunded Mandates Assessment 

Title II of the Unfunded Mandates 

Reform Act of 1995 (Pub. L. 104–4) 

requires each Federal agency to prepare 

a written statement assessing the effects 

of any Federal mandate in a proposed or 

final agency rule that may result in an 

expenditure of $100 million or more (in 

1995 dollars) in any one year by State, 

local, and Tribal governments, in the 

aggregate, or by the private sector; such 

a mandate is deemed to be a ‘‘significant 

regulatory action.’’ The FAA currently 

uses an inflation-adjusted value of 

$136.1 million in lieu of $100 million. 

This final rule does not contain such a 

mandate. The requirements of Title II do 

not apply. 

Executive Order 13132, Federalism 

The FAA has analyzed this final rule 

under the principles and criteria of 

Executive Order 13132, Federalism. We 

determined that this action will not 

have a substantial direct effect on the 

States, the relationship between the 

national government and the States, or 

on the distribution of power and 

responsibilities among the various 

levels of government. Therefore, today’s 

rule does not have federalism 

implications. 

Regulations Affecting Intrastate 

Aviation in Alaska 

Section 1205 of the FAA 

Reauthorization Act of 1996 (110 Stat. 

3213) requires the FAA, when 

modifying its regulations in a manner 

affecting intrastate aviation in Alaska, to 

consider the extent to which Alaska is 

not served by transportation modes 

other than aviation, and to establish 

appropriate regulatory distinctions. In 

the NPRM, the FAA requested 

comments on whether the proposed rule 

should apply differently to intrastate 

operations in Alaska. As discussed 

earlier, the FAA received comments on 

this subject from the late Senator 

Stevens, Senator Murkowski, and Everts 

Air Cargo and has determined that there 

would not be an adverse effect on 

intrastate air transportation in Alaska 

and that regulatory distinctions are not 

appropriate. 

Environmental Analysis 

FAA Order 1050.1E identifies FAA 

actions that are categorically excluded 

from preparation of an environmental 

assessment or environmental impact 

statement under the National 

Environmental Policy Act in the 

absence of extraordinary circumstances. 

The FAA has determined this 

rulemaking action qualifies for the 

categorical exclusion identified in 

paragraph 312f of the order and involves 

no extraordinary circumstances. 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use 

The FAA has analyzed this rule under 

Executive Order 13211, Actions 

Concerning Regulations that 

Significantly Affect Energy Supply, 

Distribution, or Use (May 18, 2001). We 

have determined that it is not a 

‘‘significant regulatory action’’ under the 

executive order because, while it is a 

‘‘significant regulatory action’’ under 

Executive Order 12866 and DOT’s 

Regulatory Policies and Procedures, it is 

not likely to have a significant adverse 

effect on the supply, distribution, or use 

of energy. 

List of Subjects 

14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements, 

Continued airworthiness. 

14 CFR Part 26 

Aircraft, Aviation safety, Continued 

airworthiness. 

14 CFR Parts 121 and 129 

Air carriers, Aircraft, Aviation safety, 

Continued airworthiness, Reporting and 

recordkeeping requirements. 

The Amendments 

■ In consideration of the foregoing, the 

Federal Aviation Administration 

amends Chapter I of Title 14, Code of 

Federal Regulations, parts 25, 26, 121, 

and 129, as follows: 

PART 25—AIRWORTHINESS 

STANDARDS: TRANSPORT 

CATEGORY AIRPLANES 

■ 1. The authority citation for part 25 

continues to read as follows: 

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

44702 and 44704. 

■ 2. Amend § 25.571 by revising 

paragraphs (a)(3) introductory text and 

(b) introductory text to read as follows: 

§ 25.571 Damage-tolerance and fatigue 

evaluation of structure. 

(a) * * * 

(3) Based on the evaluations required 

by this section, inspections or other 

procedures must be established, as 

necessary, to prevent catastrophic 

failure, and must be included in the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness required by § 25.1529. 

The limit of validity of the engineering 

data that supports the structural 

maintenance program (hereafter referred 

to as LOV), stated as a number of total 

accumulated flight cycles or flight hours 

or both, established by this section must 

also be included in the Airworthiness 

Limitations section of the Instructions 

for Continued Airworthiness required 

by § 25.1529. Inspection thresholds for 

the following types of structure must be 

established based on crack growth 

analyses and/or tests, assuming the 

structure contains an initial flaw of the 

maximum probable size that could exist 

as a result of manufacturing or serviceinduced damage: 

* * * * * 

(b) Damage-tolerance evaluation. The 

evaluation must include a 

determination of the probable locations 

and modes of damage due to fatigue, 

corrosion, or accidental damage. 

Repeated load and static analyses 

supported by test evidence and (if 

available) service experience must also 

be incorporated in the evaluation. 

Special consideration for widespread 

fatigue damage must be included where 

the design is such that this type of 

damage could occur. An LOV must be 

established that corresponds to the 

period of time, stated as a number of 

total accumulated flight cycles or flight 

hours or both, during which it is 

demonstrated that widespread fatigue 

damage will not occur in the airplane 

structure. This demonstration must be 

by full-scale fatigue test evidence. The 

type certificate may be issued prior to 

completion of full-scale fatigue testing, 

provided the Administrator has 

approved a plan for completing the 

required tests. In that case, the 

Airworthiness Limitations section of the 

Instructions for Continued 

Airworthiness required by § 25.1529 

must specify that no airplane may be 

operated beyond a number of cycles 

equal to 1⁄2 the number of cycles 

accumulated on the fatigue test article, 


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until such testing is completed. The 

extent of damage for residual strength 

evaluation at any time within the 

operational life of the airplane must be 

consistent with the initial detectability 

and subsequent growth under repeated 

loads. The residual strength evaluation 

must show that the remaining structure 

is able to withstand loads (considered as 

static ultimate loads) corresponding to 

the following conditions: 

* * * * * 

■ 3. Amend section H25.4 of Appendix 

H to part 25 by revising paragraph (a)(1) 

and adding paragraph (a)(4) to read as 

follows: 

Appendix H to Part 25—Instructions for 

Continued Airworthiness 

* * * * * 

H25.4 Airworthiness Limitations section. 

(a) * * * 

(1) Each mandatory modification time, 

replacement time, structural inspection 

interval, and related structural inspection 

procedure approved under § 25.571. 

* * * * * 

(4) A limit of validity of the engineering 

data that supports the structural maintenance 

program (LOV), stated as a total number of 

accumulated flight cycles or flight hours or 

both, approved under § 25.571. Until the fullscale fatigue testing is completed and the 

FAA has approved the LOV, the number of 

cycles accumulated by the airplane cannot be 

greater than 1⁄2 the number of cycles 

accumulated on the fatigue test article. 

* * * * * 

PART 26—CONTINUED 

AIRWORTHINESS AND SAFETY 

IMPROVEMENTS FOR TRANSPORT 

CATEGORY AIRPLANES 

■ 4. The authority citation for part 26 

continues to read as follows: 

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

44702 and 44704. 

■ 5. 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 C widespread 

fatigue damage 

Subpart D fuel tank 

flammability 

Subpart E damage 

tolerance data 

Effective date of rule ...................... December 10, 2007 ........ January 14, 2011 ........... December 26, 2008 ........ January 11, 2008 

Existing 1 TC Holders ..................... 26.11 ............................... 26.21 ............................... 26.33 ............................... 26.43, 26.45, 26.49 

Pending 1 TC Applicants ................. 26.11 ............................... 26.21 ............................... 26.37 ............................... 26.43, 26.45 

Future 2 TC applicants .................... N/A .................................. N/A .................................. N/A .................................. 26.43 

Existing 1 STC Holders ................... N/A .................................. 26.21 ............................... 26.35 ............................... 26.47, 26.49 

Pending 1 STC/ATC applicants ...... 26.11 ............................... 26.21 ............................... 26.35 ............................... 26.45, 26.47, 26.49 

Future 2 STC/ATC applicants ......... 26.11 ............................... 26.21 ............................... 26.35 ............................... 26.45, 26.47, 26.49 

Manufacturers ................................. N/A .................................. N/A .................................. 26.39 ............................... N/A 

1As of the effective date of the identified rule. 

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

■ 6. Add subpart C to read as follows: 

Subpart C—Aging Airplane Safety— 

Widespread Fatigue Damage 

Sec. 

26.21 Limit of validity. 

26.23 Extended limit of validity. 

Subpart C—Aging Airplane Safety— 

Widespread Fatigue Damage 

§ 26.21 Limit of validity. 

(a) Applicability. Except as provided 

in paragraph (g) of this section, this 

section applies to transport category, 

turbine-powered airplanes with a 

maximum takeoff gross weight greater 

than 75,000 pounds and a type 

certificate issued after January 1, 1958, 

regardless of whether the maximum 

takeoff gross weight is a result of an 

original type certificate or a later design 

change. This section also applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, if a design change 

approval for which application is made 

after January 14, 2011 has the effect of 

reducing the maximum takeoff gross 

weight from greater than 75,000 pounds 

to 75,000 pounds or less. 

(b) Limit of validity. Each person 

identified in paragraph (c) of this 

section must comply with the following 

requirements: 

(1) Establish a limit of validity of the 

engineering data that supports the 

structural maintenance program 

(hereafter referred to as LOV) that 

corresponds to the period of time, stated 

as a number of total accumulated flight 

cycles or flight hours or both, during 

which it is demonstrated that 

widespread fatigue damage will not 

occur in the airplane. This 

demonstration must include an 

evaluation of airplane structural 

configurations and be supported by test 

evidence and analysis at a minimum 

and, if available, service experience, or 

service experience and teardown 

inspection results, of high-time 

airplanes of similar structural design, 

accounting for differences in operating 

conditions and procedures. The airplane 

structural configurations to be evaluated 

include— 

(i) All model variations and 

derivatives approved under the type 

certificate; and 

(ii) All structural modifications to and 

replacements for the airplane structural 

configurations specified in paragraph 

(b)(1)(i) of this section, mandated by 

airworthiness directives as of January 

14, 2011. 

(2) If the LOV depends on 

performance of maintenance actions for 

which service information has not been 

mandated by airworthiness directive as 

of January 14, 2011, submit the 

following to the FAA Oversight Office: 

(i) For those maintenance actions for 

which service information has been 

issued as of the applicable compliance 

date specified in paragraph (c) of this 

section, a list identifying each of those 

actions. 

(ii) For those maintenance actions for 

which service information has not been 

issued as of the applicable compliance 

date specified in paragraph (c) of this 

section, a list identifying each of those 

actions and a binding schedule for 

providing in a timely manner the 

necessary service information for those 

actions. Once the FAA Oversight Office 

approves this schedule, each person 

identified in paragraph (c) of this 

section must comply with that schedule. 


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(3) Unless previously accomplished, 

establish an Airworthiness Limitations 

section (ALS) for each airplane 

structural configuration evaluated under 

paragraph (b)(1) of this section. 

(4) Incorporate the applicable LOV 

established under paragraph (b)(1) of 

this section into the ALS for each 

airplane structural configuration 

evaluated under paragraph (b)(1) and 

submit it to the FAA Oversight Office 

for approval. 

(c) Persons who must comply and 

compliance dates. The following 

persons must comply with the 

requirements of paragraph (b) of this 

section by the specified date. 

(1) Holders of type certificates (TC) of 

airplane models identified in Table 1 of 

this section: No later than the applicable 

date identified in Table 1 of this section. 

(2) Applicants for TCs, if the date of 

application was before January 14, 2011: 

No later than the latest of the following 

dates: 

(i) January 14, 2016; 

(ii) The date the certificate is issued; 

or 

(iii) The date specified in the plan 

approved under § 25.571(b) for 

completion of the full-scale fatigue 

testing and demonstrating that 

widespread fatigue damage will not 

occur in the airplane structure. 

(3) Applicants for amendments to 

TCs, with the exception of amendments 

to TCs specified in paragraphs (c)(6) or 

(c)(7) of this section, if the original TC 

was issued before January 14, 2011: No 

later than the latest of the following 

dates: 

(i) January 14, 2016; 

(ii) The date the amended certificate 

is issued; or 

(iii) The date specified in the plan 

approved under § 25.571(b) for 

completion of the full-scale fatigue 

testing and demonstrating that 

widespread fatigue damage will not 

occur in the airplane structure. 

(4) Applicants for amendments to 

TCs, with the exception of amendments 

to TCs specified in paragraphs (c)(6) or 

(c)(7) of this section, if the application 

for the original TC was made before 

January 14, 2011 but the TC was not 

issued before January 14, 2011: No later 

than the latest of the following dates: 

(i) January 14, 2016; 

(ii) The date the amended certificate 

is issued; or 

(iii) The date specified in the plan 

approved under § 25.571(b) for 

completion of the full-scale fatigue 

testing and demonstrating that 

widespread fatigue damage will not 

occur in the airplane structure. 

(5) Holders of either supplemental 

type certificates (STCs) or amendments 

to TCs that increase maximum takeoff 

gross weights from 75,000 pounds or 

less to greater than 75,000 pounds: No 

later than July 14, 2012. 

(6) Applicants for either STCs or 

amendments to TCs that increase 

maximum takeoff gross weights from 

75,000 pounds or less to greater than 

75,000 pounds: No later than the latest 

of the following dates: 

(i) July 14, 2012; 

(ii) The date the certificate is issued; 

or 

(iii) The date specified in the plan 

approved under § 25.571(b) for 

completion of the full-scale fatigue 

testing and demonstrating that 

widespread fatigue damage will not 

occur in the airplane structure. 

(7) Applicants for either STCs or 

amendments to TCs that decrease 

maximum takeoff gross weights from 

greater than 75,000 pounds to 75,000 

pounds or less, if the date of application 

was after January 14, 2011: No later than 

the latest of the following dates: 

(i) July 14, 2012; 

(ii) The date the certificate is issued; 

or 

(iii) The date specified in the plan 

approved under § 25.571(b) for 

completion of the full-scale fatigue 

testing and demonstrating that 

widespread fatigue damage will not 

occur in the airplane structure. 

(d) Compliance plan. Each person 

identified in paragraph (e) of this 

section must submit a compliance plan 

consisting of the following: 

(1) A proposed project schedule, 

identifying all major milestones, for 

meeting the compliance dates specified 

in paragraph (c) of this section. 

(2) A proposed means of compliance 

with paragraphs (b)(1) through (b)(4) of 

this section. 

(3) A proposal for submitting a draft 

of all compliance items required by 

paragraph (b) of this section for review 

by the FAA Oversight Office not less 

than 60 days before the compliance date 

specified in paragraph (c) of this 

section, as applicable. 

(4) A proposal for how the LOV will 

be distributed. 

(e) Compliance dates for compliance 

plans. The following persons must 

submit the compliance plan described 

in paragraph (d) of this section to the 

FAA Oversight Office by the specified 

date. 

(1) Holders of type certificates: No 

later than April 14, 2011. 

(2) Applicants for TCs and 

amendments to TCs, with the exception 

of amendments to TCs specified in 

paragraphs (e)(4), (e)(5), or (e)(6) of this 

section, if the date of application was 

before January 14, 2011 but the TC or 

TC amendment was not issued before 

January 14, 2011: No later than April 14, 

2011. 

(3) Holders of either supplemental 

type certificates or amendments to TCs 

that increase maximum takeoff gross 

weights from 75,000 pounds or less to 

greater than 75,000 pounds: No later 

than April 14, 2011. 

(4) Applicants for either STCs or 

amendments to TCs that increase 

maximum takeoff gross weights from 

75,000 pounds or less to greater than 

75,000 pounds, if the date of application 

was before January 14, 2011: No later 

than April 14, 2011. 

(5) Applicants for either STCs or 

amendments to TCs that increase 

maximum takeoff gross weights from 

75,000 pounds or less to greater than 

75,000 pounds, if the date of application 

is on or after January 14, 2011: Within 

90 days after the date of application. 

(6) Applicants for either STCs or 

amendments to TCs that decrease 

maximum takeoff gross weights from 

greater than 75,000 pounds to 75,000 

pounds or less, if the date of application 

is on or after January 14, 2011: Within 

90 days after the date of application. 

(f) Compliance plan implementation. 

Each affected person must implement 

the compliance plan as approved in 

compliance with paragraph (d) of this 

section. 

(g) Exceptions. This section does not 

apply to the following airplane models: 

(1) Bombardier BD–700. 

(2) Bombardier CL–44. 

(3) Gulfstream GV. 

(4) Gulfstream GV–SP. 

(5) British Aerospace, Aircraft Group, 

and Societe Nationale Industrielle 

Aerospatiale Concorde Type 1. 

(6) British Aerospace (Commercial 

Aircraft) Ltd., Armstrong Whitworth 

Argosy A.W. 650 Series 101. 

(7) British Aerospace Airbus, Ltd., 

BAC 1–11. 

(8) BAE Systems (Operations) Ltd., 

BAe 146. 

(9) BAE Systems (Operations) Ltd., 

Avro 146. 

(10) Lockheed 300–50A01 (USAF 

C141A). 

(11) Boeing 707. 

(12) Boeing 720. 

(13) deHavilland D.H. 106 Comet 4C. 

(14) Ilyushin Aviation IL–96T. 

(15) Bristol Aircraft Britannia 305. 

(16) Avions Marcel Dassault-Breguet 

Aviation Mercure 100C. 

(17) Airbus Caravelle. 

(18) D & R Nevada, LLC, Convair 

Model 22. 

(19) D & R Nevada, LLC, Convair 

Model 23M. 


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TABLE 1—COMPLIANCE DATES FOR AFFECTED AIRPLANES

Airplane model 

(all existing 1 models) 

Compliance date— 

(months after 

January 14, 2011) 

Airbus: 

A300 Series, A310 Series, A300–600 Series .................................................................................................................. 18 

A318 Series ...................................................................................................................................................................... 48 

A319 Series ...................................................................................................................................................................... 48 

A320 Series ...................................................................................................................................................................... 48 

A321 Series ...................................................................................................................................................................... 48 

A330–200, –200 Freighter, –300 Series .......................................................................................................................... 48 

A340–200, –300, –500, –600 Series ............................................................................................................................... 48 

A380–800 Series .............................................................................................................................................................. 60 

Boeing: 

717 .................................................................................................................................................................................... 48 

727 (all series) .................................................................................................................................................................. 18 

737 (Classics): 737–100, –200, –200C, –300, –400, –500 ............................................................................................. 18 

737 (NG): 737–600, –700, –700C, –800, –900, –900ER ................................................................................................ 48 

747 (Classics): 747–100, –100B, –100B SUD, –200B, -200C, –200F, –300, 747SP, 747SR ....................................... 18 

747–400: 747–400, –400D, –400F .................................................................................................................................. 48 

757 .................................................................................................................................................................................... 48 

767 .................................................................................................................................................................................... 48 

777–200, –300 .................................................................................................................................................................. 48 

777–200LR, 777–300ER, 777F ........................................................................................................................................ 60 

Bombardier: 

CL–600: 2D15 (Regional Jet Series 705), 2D24 (Regional Jet Series 900) ................................................................... 60 

Embraer: 

ERJ 170 ............................................................................................................................................................................ 60 

ERJ 190 ............................................................................................................................................................................ 60 

Fokker: 

F.28 Mark 0070, Mark 0100 ............................................................................................................................................. 18 

Lockheed: 

L–1011 .............................................................................................................................................................................. 18 

188 .................................................................................................................................................................................... 18 

382 (all series) .................................................................................................................................................................. 18 

McDonnell Douglas: 

DC–8, –8F ........................................................................................................................................................................ 18 

DC–9 ................................................................................................................................................................................. 18 

MD–80 (DC–9–81, –82, –83, –87, MD–88) ..................................................................................................................... 18 

MD–90 .............................................................................................................................................................................. 48 

DC–10 ............................................................................................................................................................................... 18 

MD–10 .............................................................................................................................................................................. 48 

MD–11, –11F .................................................................................................................................................................... 48 

All Other Airplane Models Listed on a Type Certificate as of January 14, 2011 ................................................................... 60 

1Type certificated as of January 14, 2011. 

§ 26.23 Extended limit of validity. 

(a) Applicability. Any person may 

apply to extend a limit of validity of the 

engineering data that supports the 

structural maintenance program 

(hereafter referred to as LOV) approved 

under § 25.571 of this subchapter, 

§ 26.21, or this section. Extending an 

LOV is a major design change. The 

applicant must comply with the 

relevant provisions of subparts D or E of 

part 21 of this subchapter and paragraph 

(b) of this section. 

(b) Extended limit of validity. Each 

person applying for an extended LOV 

must comply with the following 

requirements: 

(1) Establish an extended LOV that 

corresponds to the period of time, stated 

as a number of total accumulated flight 

cycles or flight hours or both, during 

which it is demonstrated that 

widespread fatigue damage will not 

occur in the airplane. This 

demonstration must include an 

evaluation of airplane structural 

configurations and be supported by test 

evidence and analysis at a minimum 

and, if available, service experience, or 

service experience and teardown 

inspection results, of high-time 

airplanes of similar structural design, 

accounting for differences in operating 

conditions and procedures. The airplane 

structural configurations to be evaluated 

include— 

(i) All model variations and 

derivatives approved under the type 

certificate for which approval for an 

extension is sought; and 

(ii) All structural modifications to and 

replacements for the airplane structural 

configurations specified in paragraph 

(b)(1)(i) of this section, mandated by 

airworthiness directive, up to the date of 

approval of the extended LOV. 

(2) Establish a revision or supplement, 

as applicable, to the Airworthiness 

Limitations section (ALS) of the 

Instructions for Continued 

Airworthiness required by § 25.1529 of 

this subchapter, and submit it to the 

FAA Oversight Office for approval. The 

revised ALS or supplement to the ALS 

must include the applicable extended 

LOV established under paragraph (b)(1) 

of this section. 

(3) Develop the maintenance actions 

determined by the WFD evaluation 

performed in paragraph (b)(1) of this 

section to be necessary to preclude WFD 

from occurring before the airplane 

reaches the proposed extended LOV. 

These maintenance actions must be 

documented as airworthiness limitation 

items in the ALS and submitted to the 

FAA Oversight Office for approval. 


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PART 121—OPERATING 

REQUIREMENTS: DOMESTIC, FLAG, 

AND SUPPLEMENTAL OPERATIONS 

■ 7. The authority citation for part 121 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 40119, 

41706, 44101, 44701–44702, 44705, 44709– 

44711, 44713, 44716–44717, 44722, 44901, 

44903–44904, 44912, 45101–45105, 46105, 

46301. 

■ 8. Add new § 121.1115 to read as 

follows: 

§ 121.1115 Limit of validity. 

(a) Applicability. This section applies 

to certificate holders operating any 

transport category, turbine-powered 

airplane with a maximum takeoff gross 

weight greater than 75,000 pounds and 

a type certificate issued after January 1, 

1958, regardless of whether the 

maximum takeoff gross weight is a 

result of an original type certificate or a 

later design change. This section also 

applies to certificate holders operating 

any transport category, turbine-powered 

airplane with a type certificate issued 

after January 1, 1958, regardless of the 

maximum takeoff gross weight, for 

which a limit of validity of the 

engineering data that supports the 

structural maintenance program 

(hereafter referred to as LOV) is required 

in accordance with § 25.571 or § 26.21 

of this chapter after January 14, 2011. 

(b) Limit of validity. No certificate 

holder may operate an airplane 

identified in paragraph (a) of this 

section after the applicable date 

identified in Table 1 of this section 

unless an Airworthiness Limitations 

section approved under Appendix H to 

part 25 or § 26.21 of this chapter is 

incorporated into its maintenance 

program. The ALS must— 

(1) Include an LOV approved under 

§ 25.571 or § 26.21 of this chapter, as 

applicable, except as provided in 

paragraph (f) of this section; and 

(2) Be clearly distinguishable within 

its maintenance program. 

(c) Operation of airplanes excluded 

from § 26.21. No certificate holder may 

operate an airplane identified in 

§ 26.21(g) of this chapter after July 14, 

2013, unless an Airworthiness 

Limitations section approved under 

Appendix H to part 25 or § 26.21 of this 

chapter is incorporated into its 

maintenance program. The ALS must— 

(1) Include an LOV approved under 

§ 25.571 or § 26.21 of this chapter, as 

applicable, except as provided in 

paragraph (f) of this section; and 

(2) Be clearly distinguishable within 

its maintenance program. 

(d) Extended limit of validity. No 

certificate holder may operate an 

airplane beyond the LOV, or extended 

LOV, specified in paragraph (b)(1), (c), 

(d), or (f) of this section, as applicable, 

unless the following conditions are met: 

(1) An ALS must be incorporated into 

its maintenance program that— 

(i) Includes an extended LOV and any 

widespread fatigue damage 

airworthiness limitation items approved 

under § 26.23 of this chapter; and 

(ii) Is approved under § 26.23 of this 

chapter. 

(2) The extended LOV and the 

airworthiness limitation items 

pertaining to widespread fatigue damage 

must be clearly distinguishable within 

its maintenance program. 

(e) Principal Maintenance Inspector 

approval. Certificate holders must 

submit the maintenance program 

revisions required by paragraphs (b), (c), 

and (d) of this section to the Principal 

Maintenance Inspector for review and 

approval. 

(f) Exception. For any airplane for 

which an LOV has not been approved as 

of the applicable compliance date 

specified in paragraph (c) or Table 1 of 

this section, instead of including an 

approved LOV in the ALS, an operator 

must include the applicable default 

LOV specified in Table 1 or Table 2 of 

this section, as applicable, in the ALS. 

TABLE 1—AIRPLANES SUBJECT TO § 26.21 

Airplane model 

Compliance date— 

months after 

January 14, 2011 

Default LOV 

[flight cycles (FC) 

or flight hours (FH)] 

Airbus—Existing1 Models Only: 

A300 B2–1A, B2–1C, B2K–3C, B2–203 ............................................................. 30 ............................................ 48,000 FC 

A300 B4–2C, B4–103 ......................................................................................... 30 ............................................ 40,000 FC 

A300 B4–203 ....................................................................................................... 30 ............................................ 34,00 FC 

A300–600 Series ................................................................................................. 30 ............................................ 30,000 FC/67,500 FH 

A310–200 Series ................................................................................................. 30 ............................................ 40,000 FC/60,000 FH 

A310–300 Series ................................................................................................. 30 ............................................ 35,000 FC/60,000 FH 

A318 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A319 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A320–100 Series ................................................................................................. 60 ............................................ 48,000 FC/48,000 FH 

A320–200 Series ................................................................................................. 60 ............................................ 48,000 FC/60,000 FH 

A321 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A330–200, –300 Series (except WV050 family) (non enhanced) ...................... 60 ............................................ 40,000 FC/60,000 FH 

A330–200, –300 Series WV050 family (enhanced) ............................................ 60 ............................................ 33,000 FC/100,000 FH 

A330–200 Freighter Series ................................................................................. 60 ............................................ See NOTE. 

A340–200, –300 Series (except WV 027 and WV050 family) (non enhanced) 60 ............................................ 20,000 FC/80,000 FH 

A340–200, –300 Series WV 027 (non enhanced) .............................................. 60 ............................................ 30,000 FC/60,000 FH 

A340–300 Series WV050 family (enhanced) ...................................................... 60 ............................................ 20,000 FC/100,000 FH 

A340–500, –600 Series ....................................................................................... 60 ............................................ 16,600 FC/100,000 FH 

A380–800 Series ................................................................................................. 72 ............................................ See NOTE. 

Boeing—Existing1 Models Only: 

717 ....................................................................................................................... 60 ............................................ 60,000 FC/60,000 FH 

727 (all series) ..................................................................................................... 30 ............................................ 60,000 FC 

737 (Classics): 737–100, –200, –200C, –300, –400, –500 ................................ 30 ............................................ 75,000 FC 

737 (NG): 737–600, –700, –700C, –800, –900, –900ER ................................... 60 ............................................ 75,000 FC 

747 (Classics): 747–100, –100B, –100B SUD, –200B, –200C, –200F, –300, 

747SP, 747SR.

30 ............................................ 20,000 FC 

747–400: 747–400, –400D, –400F ..................................................................... 60 ............................................ 20,000 FC 

757 ....................................................................................................................... 60 ............................................ 50,000 FC 

767 ....................................................................................................................... 60 ............................................ 50,000 FC 

777–200, –300 .................................................................................................... 60 ............................................ 40,000 FC 


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69786 Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 

TABLE 1—AIRPLANES SUBJECT TO § 26.21—Continued 

Airplane model 

Compliance date— 

months after 

January 14, 2011 

Default LOV 

[flight cycles (FC) 

or flight hours (FH)] 

777–200LR, 777–300ER ..................................................................................... 72 ............................................ 40,000 FC 

777F .................................................................................................................... 72 ............................................ 11,000 FC 

Bombardier—Existing1 Models Only: 

CL–600: 2D15 (Regional Jet Series 705), 2D24 (Regional Jet Series 900) ...... 72 ............................................ 60,000 FC 

Embraer—Existing1 Models Only: 

ERJ 170 ............................................................................................................... 72 ............................................ See NOTE. 

ERJ 190 ............................................................................................................... 72 ............................................ See NOTE. 

Fokker—Existing1 Models Only: 

F.28 Mark 0070, Mark 0100 ................................................................................ 30 ............................................ 90,000 FC 

Lockheed—Existing1 Models Only: 

L–1011 ................................................................................................................. 30 ............................................ 36,000 FC 

188 ....................................................................................................................... 30 ............................................ 26,600 FC 

382 (all series) ..................................................................................................... 30 ............................................ 20,000 FC/50,000 FH 

McDonnell Douglas—Existing1 Models Only: 

DC–8, –8F ........................................................................................................... 30 ............................................ 50,000 FC/50,000 FH 

DC–9 (except for MD–80 models) ...................................................................... 30 ............................................ 100,000 FC/100,000 FH 

MD–80 (DC–9–81, –82, –83, –87, MD–88) ........................................................ 30 ............................................ 50,000 FC/50,000 FH 

MD–90 ................................................................................................................. 60 ............................................ 60,000 FC/90,000 FH 

DC–10–10, –15 ................................................................................................... 30 ............................................ 42,000 FC/60,000 FH 

DC–10–30, –40, –10F, –30F, –40F .................................................................... 30 ............................................ 30,000 FC/60,000 FH 

MD–10–10F ......................................................................................................... 60 ............................................ 42,000 FC/60,000 FH 

MD–10–30F ......................................................................................................... 60 ............................................ 30,000 FC/60,000 FH 

MD–11, MD–11F ................................................................................................. 60 ............................................ 20,000 FC/60,000 FH 

Maximum Takeoff Gross Weight Changes: 

All airplanes whose maximum takeoff gross weight has been decreased to 

75,000 pounds or below after January 14, 2011 or increased to greater 

than 75,000 pounds at any time by an amended type certificate or supplemental type certificate.

30, or within 12 months after 

the LOV is approved, or before operating the airplane, 

whichever occurs latest.

Not applicable. 

All Other Airplane Models (TCs and amended TCs) not Listed in Table 2 ............... 72, or within 12 months after 

the LOV is approved, or before operating the airplane, 

whichever occurs latest.

Not applicable. 

1Type certificated as of January 14, 2011. 

Note: Airplane operation limitation is 

stated in the Airworthiness Limitation 

section. 

TABLE 2—AIRPLANES EXCLUDED FROM § 26.21 

Airplane model 

Default LOV 

[flight cycles (FC) 

or flight hours (FH)] 

Airbus: 

Caravelle ........................................................................................................................................................................ 15,000 FC/24,000 FH 

Avions Marcel Dassault: 

Breguet Aviation Mercure 100C ..................................................................................................................................... 20,000 FC/16,000 FH 

Boeing: 

Boeing 707 (-100 Series and -200 Series) .................................................................................................................... 20,000 FC 

Boeing 707 (-300 Series and -400 Series) .................................................................................................................... 20,000 FC 

Boeing 720 ..................................................................................................................................................................... 30,000 FC 

Bombardier: 

CL–44D4 and CL–44J .................................................................................................................................................... 20,000 FC 

BD–700 .......................................................................................................................................................................... 15,000 FH 

Bristol Aeroplane Company: 

Britannia 305 .................................................................................................................................................................. 10,000 FC 

British Aerospace Airbus, Ltd.: 

BAC 1–11 (all models) ................................................................................................................................................... 85,000 FC 

British Aerospace (Commercial Aircraft) Ltd.: 

Armstrong Whitworth Argosy A.W. 650 Series 101 ....................................................................................................... 20,000 FC 

BAE Systems (Operations) Ltd.: 

BAe 146–100A (all models) ........................................................................................................................................... 50,000 FC 

BAe 146–200–07 ........................................................................................................................................................... 50,000 FC 

BAe 146–200–07 Dev .................................................................................................................................................... 50,000 FC 

BAe 146–200–11 ........................................................................................................................................................... 50,000 FC 

BAe 146–200–07A ......................................................................................................................................................... 47,000 FC 

BAe 146–200–11 Dev .................................................................................................................................................... 43,000 FC 


jlentini on DSKJ8SOYB1PROD with RULES2
Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 69787 

TABLE 2—AIRPLANES EXCLUDED FROM § 26.21—Continued 

Airplane model 

Default LOV 

[flight cycles (FC) 

or flight hours (FH)] 

BAe 146–300 (all models) .............................................................................................................................................. 40,000 FC 

Avro 146–RJ70A (all models) ........................................................................................................................................ 40,000 FC 

Avro 146–RJ85A and 146–RJ100A (all models) ........................................................................................................... 50,000 FC 

D & R Nevada, LLC: 

Convair Model 22 ........................................................................................................................................................... 1,000 FC/1,000 FH 

Convair Model 23M ........................................................................................................................................................ 1,000 FC/1,000 FH 

deHavilland Aircraft Company, Ltd.: 

D.H. 106 Comet 4C ........................................................................................................................................................ 8,000 FH 

Gulfstream: 

GV .................................................................................................................................................................................. 40,000 FH 

GV–SP ........................................................................................................................................................................... 40,000 FH 

Ilyushin Aviation Complex: 

IL–96T ............................................................................................................................................................................ 10,000 FC/30,000 FH 

Lockheed: 

300–50A01 (USAF C 141A) ........................................................................................................................................... 20,000 FC 

PART 129—OPERATIONS: FOREIGN 

AIR CARRIERS AND FOREIGN 

OPERATORS OF U.S.-REGISTERED 

AIRCRAFT ENGAGED IN COMMON 

CARRIAGE 

■ 9. The authority citation for part 129 

continues to read: 

Authority: 49 U.S.C. 1372, 40113, 40119, 

44101, 44701–44702, 44705, 44709–44711, 

44713, 44716–44717, 44722, 44901–44904, 

44906, 44912, 46105, Pub. L. 107–71 sec. 

104. 

■ 10. Add new § 129.115 to read as 

follows: 

§ 129.115 Limit of validity. 

(a) Applicability. This section applies 

to foreign air carriers or foreign persons 

operating any U.S.-registered transport 

category, turbine-powered airplane with 

a maximum takeoff gross weight greater 

than 75,000 pounds and a type 

certificate issued after January 1, 1958, 

regardless of whether the maximum 

takeoff gross weight is a result of an 

original type certificate or a later design 

change. This section also applies to 

foreign air carriers or foreign persons 

operating any other U.S.-registered 

transport category, turbine-powered 

airplane with a type certificate issued 

after January 1, 1958, regardless of the 

maximum takeoff gross weight, for 

which a limit of validity of the 

engineering data that supports the 

structural maintenance program 

(hereafter referred to as LOV) is required 

in accordance with § 25.571 or § 26.21 

of this chapter after January 14, 2011. 

(b) Limit of validity. No foreign air 

carrier or foreign person may operate a 

U.S.-registered airplane identified in 

paragraph (a) of this section after the 

applicable date identified in Table 1 of 

this section, unless an Airworthiness 

Limitations section (ALS) approved 

under Appendix H to part 25 or § 26.21 

of this chapter is incorporated into its 

maintenance program. The ALS must— 

(1) Include an LOV approved under 

§ 25.571 or § 26.21 of this chapter, as 

applicable, except as provided in 

paragraph (f) of this section; and 

(2) Be clearly distinguishable within 

its maintenance program. 

(c) Operation of airplanes excluded 

from § 26.21. No certificate holder may 

operate an airplane identified in 

§ 26.21(g) of this chapter after July 14, 

2013, unless an ALS approved under 

Appendix H to part 25 or § 26.21 of this 

chapter is incorporated into its 

maintenance program. The ALS must— 

(1) Include an LOV approved under 

§ 25.571 or § 26.21 of this chapter, as 

applicable, except as provided in 

paragraph (f) of this section; and 

(2) Be clearly distinguishable within 

its maintenance program 

(d) Extended limit of validity. No 

foreign air carrier or foreign person may 

operate an airplane beyond the LOV or 

extended LOV specified in paragraph 

(b)(1), (c), (d), or (f) of this section, as 

applicable, unless the following 

conditions are met: 

(1) An ALS must be incorporated into 

its maintenance program that— 

(i) Includes an extended LOV and any 

widespread fatigue damage 

airworthiness limitation items (ALIs) 

approved under § 26.23 of this chapter; 

and 

(ii) Is approved under § 26.23 of this 

chapter; 

(2) The extended LOV and the 

airworthiness limitation items 

pertaining to widespread fatigue damage 

must be clearly distinguishable within 

its maintenance program. 

(e) Principal Maintenance Inspector 

approval. Foreign air carriers or foreign 

persons must submit the maintenance 

program revisions required by 

paragraphs (b), (c), and (d) of this 

section to the Principal Maintenance 

Inspector or Flight Standards 

International Field Office for review and 

approval. 

(f) Exception. For any airplane for 

which an LOV has not been approved as 

of the applicable compliance date 

specified in paragraph (c) or Table 1 of 

this section, instead of including an 

approved LOV in the ALS, an operator 

must include the applicable default 

LOV specified in Table 1 or Table 2 of 

this section, as applicable, in the ALS. 

TABLE 1—AIRPLANES SUBJECT TO § 26.21 

Airplane model Compliance date—months 

after January 14, 2011 

Default LOV [flight 

cycles (FC) or flight hours 

(FH)] 

Airbus—Existing 1 Models Only: 

A300 B2–1A, B2–1C, B2K–3C, B2–203 ............................................................. 30 ............................................ 48,000 FC 

A300 B4–2C, B4–103 ......................................................................................... 30 ............................................ 40,000 FC 

A300 B4–203 ....................................................................................................... 30 ............................................ 34,000 FC 

A300–600 Series ................................................................................................. 30 ............................................ 30,000 FC/67,500 FH 


jlentini on DSKJ8SOYB1PROD with RULES2
69788 Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 

TABLE 1—AIRPLANES SUBJECT TO § 26.21—Continued 

Airplane model Compliance date—months 

after January 14, 2011 

Default LOV [flight 

cycles (FC) or flight hours 

(FH)] 

A310–200 Series ................................................................................................. 30 ............................................ 40,000 FC/60,000 FH 

A310–300 Series ................................................................................................. 30 ............................................ 35,000 FC/60,000 FH 

A318 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A319 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A320–100 Series ................................................................................................. 60 ............................................ 48,000 FC/48,000 FH 

A320–200 Series ................................................................................................. 60 ............................................ 48,000 FC/60,000 FH 

A321 Series ......................................................................................................... 60 ............................................ 48,000 FC/60,000 FH 

A330–200, –300 Series (except WV050 family) (non enhanced) ...................... 60 ............................................ 40,000 FC/60,000 FH 

A330–200, –300 Series WV050 family (enhanced) ............................................ 60 ............................................ 33,000 FC/100,000 FH 

A330–200 Freighter Series ................................................................................. 60 ............................................ See NOTE. 

A340–200, –300 Series (except WV 027 and WV050 family) (non enhanced) 60 ............................................ 20,000 FC/80,000 FH 

A340–200, –300 Series WV 027 (non enhanced) .............................................. 60 ............................................ 30,000 FC/60,000 FH 

A340–300 Series WV050 family (enhanced) ...................................................... 60 ............................................ 20,000 FC/100,000 FH 

A340–500, –600 Series ....................................................................................... 60 ............................................ 16,600 FC/100,000 FH 

A380–800 Series ................................................................................................. 72 ............................................ See NOTE. 

Boeing—Existing 1 Models Only: 

717 ....................................................................................................................... 60 ............................................ 60,000 FC/60,000 FH 

727 (all series) ..................................................................................................... 30 ............................................ 60,000 FC 

737 (Classics): 737–100, –200, –200C, –300, –400, –500 ................................ 30 ............................................ 75,000 FC 

737 (NG): 737–600, –700, –700C, –800, –900, –900ER ................................... 60 ............................................ 75,000 FC 

747 (Classics): 747–100, –100B, –100B SUD, –200B, –200C, –200F, –300, 

747SP, 747SR.

30 ............................................ 20,000 FC 

747–400: 747–400, –400D, –400F ..................................................................... 60 ............................................ 20,000 FC 

757 ....................................................................................................................... 60 ............................................ 50,000 FC 

767 ....................................................................................................................... 60 ............................................ 50,000 FC 

777–200, –300 .................................................................................................... 60 ............................................ 40,000 FC 

777–200LR, 777–300ER ..................................................................................... 72 ............................................ 40,000 FC 

777F .................................................................................................................... 72 ............................................ 11,000 FC 

Bombardier—Existing 1 Models Only: 

CL–600: 2D15 (Regional Jet Series 705), 2D24 (Regional Jet Series 900) ...... 72 ............................................ 60,000 FC 

Embraer—Existing 1 Models Only: 

ERJ 170 ............................................................................................................... 72 ............................................ See NOTE. 

ERJ 190 ............................................................................................................... 72 ............................................ See NOTE. 

Fokker—Existing 1 Models Only: 

F.28 Mark 0070, Mark 0100 ................................................................................ 30 ............................................ 90,000 FC 

Lockheed—Existing 1 Models Only: 

L–1011 ................................................................................................................. 30 ............................................ 36,000 FC 

188 ....................................................................................................................... 30 ............................................ 26,600 FC 

382 (all series) ..................................................................................................... 30 ............................................ 20,000 FC/50,000 FH 

McDonnell Douglas—Existing 1 Models Only: 

DC–8, –8F ........................................................................................................... 30 ............................................ 50,000 FC/50,000 FH 

DC–9 (except for MD–80 series) ........................................................................ 30 ............................................ 100,000 FC/100,000 FH 

MD–80 (DC–9–81, –82, –83, –87, MD–88) ........................................................ 30 ............................................ 50,000 FC/50,000 FH 

MD–90 ................................................................................................................. 60 ............................................ 60,000 FC/90,000 FH 

DC–10–10, –15 ................................................................................................... 30 ............................................ 42,000 FC/60,000 FH 

DC–10–30, –40, –10F, –30F, –40F .................................................................... 30 ............................................ 30,000 FC/60,000 FH 

MD–10–10F ......................................................................................................... 60 ............................................ 42,000 FC/60,000 FH 

MD–10–30F ......................................................................................................... 60 ............................................ 30,000 FC/60,000 FH 

MD–11, MD–11F ................................................................................................. 60 ............................................ 20,000 FC/60,000 FH 

Maximum Takeoff Gross Weight Changes ................................................................ 30, or within 12 months after 

the LOV is approved, or before operating the airplane, 

whichever occurs latest.

Not applicable. 

All airplanes whose maximum takeoff gross weight has been decreased to 75,000 

pounds or below after January 14, 2011 or increased to greater than 75,000 

pounds at any time by an amended type certificate or supplemental type certificate.

All Other Airplane Models (TCs and amended TCs) not Listed in Table 2 ............... 72, or within 12 months after 

the LOV is approved, or before operating the airplane, 

whichever occurs latest.

Not applicable. 

1Type certificated as of January 14, 2011. 

Note: Airplane operation limitation is 

stated in the Airworthiness Limitation 

section. 


jlentini on DSKJ8SOYB1PROD with RULES2
Federal Register / Vol. 75, No. 219 / Monday, November 15, 2010 / Rules and Regulations 69789 

TABLE 2—AIRPLANES EXCLUDED FROM § 26.21 

Airplane model 

Default LOV [flight 

cycles (FC) or flight 

hours (FH)] 

Airbus: 

Caravelle ........................................................................................................................................................................ 15,000 FC/24,000 FH 

Avions Marcel Dassault: 

Breguet Aviation Mercure 100C ..................................................................................................................................... 20,000 FC/16,000 FH 

Boeing: 

Boeing 707 (–100 Series and –200 Series) .................................................................................................................. 20,000 FC 

Boeing 707 (–300 Series and –400 Series) .................................................................................................................. 20,000 FC 

Boeing 720 ..................................................................................................................................................................... 30,000 FC 

Bombardier: 

CL–44D4 and CL–44J .................................................................................................................................................... 20,000 FC 

BD–700 .......................................................................................................................................................................... 15,000 FH 

Bristol Aeroplane Company: 

Britannia 305 .................................................................................................................................................................. 10,000 FC 

British Aerospace Airbus, Ltd.: 

BAC 1–11 (all models) ................................................................................................................................................... 85,000 FC 

British Aerospace (Commercial Aircraft) Ltd.: 

Armstrong Whitworth Argosy A.W. 650 Series 101 ....................................................................................................... 20,000 FC 

BAE Systems (Operations) Ltd.: 

BAe 146–100A (all models) ........................................................................................................................................... 50,000 FC 

BAe 146–200–07 ........................................................................................................................................................... 50,000 FC 

BAe 146–200–07 Dev .................................................................................................................................................... 50,000 FC 

BAe 146–200–11 ........................................................................................................................................................... 50,000 FC 

BAe 146–200–07A ......................................................................................................................................................... 47,000 FC 

BAe 146–200–11 Dev .................................................................................................................................................... 43,000 FC 

BAe 146–300 (all models) .............................................................................................................................................. 40,000 FC 

Avro 146–RJ70A (all models) ........................................................................................................................................ 40,000 FC 

Avro 146–RJ85A and 146–RJ100A (all models) ........................................................................................................... 50,000 FC 

D & R Nevada, LLC: 

Convair Model 22 ........................................................................................................................................................... 1,000 FC/1,000 FH 

Convair Model 23M ........................................................................................................................................................ 1,000 FC/1,000 FH 

deHavilland Aircraft Company, Ltd.: 

D.H. 106 Comet 4C ........................................................................................................................................................ 8,000 FH 

Gulfstream: 

GV .................................................................................................................................................................................. 40,000 FH 

GV–SP ........................................................................................................................................................................... 40,000 FH 

Ilyushin Aviation Complex: 

IL–96T ............................................................................................................................................................................ 10,000 FC/30,000 FH 

Lockheed: 

300–50A01 (USAF C 141A) ........................................................................................................................................... 20,000 FC 

Issued in Washington, DC, on October 28, 

2010. 

J. Randolph Babbitt, 

Administrator. 

[FR Doc. 2010–28363 Filed 11–12–10; 8:45 am] 

BILLING CODE 4910–13–P 


jlentini on DSKJ8SOYB1PROD with RULES2