Aging Airplane Safety, 5518-5534 [05-1756]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 21 (Wednesday, February 2, 2005)]
[Rules and Regulations]
[Pages 5518-5534]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-1756]



[[Page 5517]]

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Part II





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 119, 121, 129, 135, and 183



Aging Airplane Safety; Final Rule

Federal Register / Vol. 70, No. 21 / Wednesday, February 2, 2005 / 
Rules and Regulations

[[Page 5518]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 119, 121, 129, 135, and 183

[Docket No. FAA-1999-5401; Amendment Nos. 119-6, 121-284, 129-34, 135-
81, and 183-11]
RIN 2120-AE42


Aging Airplane Safety

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; disposition of comments.

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SUMMARY: This action adopts the interim final rule published on 
December 6, 2002, as a final rule with changes. The IFR imposed 
statutory requirements from the Aging Aircraft Safety Act of 1991 for 
certain airplanes to undergo inspections and records reviews after 
their 14th year in service and at specified intervals after that. Also, 
the rule imposed a requirement to include supplemental inspections by 
specified deadlines in the maintenance programs for these airplanes. 
With this action, the FAA responds to comments to the IFR, further 
clarifies parts of the rule language, and substantially revises the 
supplemental inspection requirements.

DATES: The interim final rule became effective December 8, 2003. This 
final rule becomes effective March 4, 2005.

FOR FURTHER INFORMATION CONTACT: Frederick Sobeck, Aircraft Maintenance 
Division, AFS-308, Flight Standards Service, Federal Aviation 
Administration, 800 Independence Avenue, SW., Washington, DC 20591; 
telephone (202) 267-7355; facsimile (202) 267-5115.

SUPPLEMENTARY INFORMATION:

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (https://dms.dot.gov/search);
    (2) Visiting the Office of Rulemaking's Web page at https://
www.faa.gov/avr/arm/index.cfm; or
    (3) Accessing the Government Printing Office's Web page at https://
www.gpoaccess.gov/fr/.
    You can also get a copy by sending a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make 
sure to identify the amendment number or docket number of this 
rulemaking.
    Anyone can search the electronic form of comments to any of our 
dockets using the name of the individual who sent the comment. You can 
also search by the person who signed the comment if, for example, an 
association, business, or labor union, sent the comment. You may review 
DOT's complete Privacy Act statement in the Federal Register published 
on April 11, 2000 (Volume 65, Number 70; Pages 19477-78), or you may 
visit https://dms.dot.gov.

Small Business Regulatory Enforcement Fairness Act

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

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, Section 106 
describes the authority of the FAA Administrator. Subtitle VII, 
Aviation Programs, describes in more detail the scope of the agency's 
authority.
    This rulemaking is promulgated under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, General requirements 
and Section 44717, Aging aircraft. Under section 44701 the 
Administrator is charged with prescribing ``regulations and minimum 
standards in the interest of safety for inspecting, servicing, and 
overhauling aircraft, aircraft engines, propellers, and appliances.'' 
Under section 44717 the Administrator is charged with prescribing 
``regulations that ensure the continuing airworthiness of aging 
aircraft.'' In accordance with those regulations the Administrator must 
``make inspections, and review the maintenance and other records, of 
each aircraft an air carrier uses to provide air transportation that 
the Administrator decides may be necessary to enable the Administrator 
to decide whether the aircraft is in a safe condition and maintained 
properly for operation in air transportation.'' These inspections and 
reviews ``shall be carried out as part of each heavy maintenance check 
of the aircraft conducted after the 14th year in which the aircraft has 
been in service.''
    This regulation is within the scope of section 44701 since it 
establishes requirements and minimum standards for the inspection of 
aging aircraft and establishes requirements for the inclusion of 
supplemental inspections in aircraft maintenance programs. 
Additionally, the regulation specifically responds to the statutory 
mandate prescribed in section 44717 by establishing a requirement for 
certain airplanes to undergo inspections and records reviews after 
their 14th year in service and at specified intervals thereafter.

Background

    This final rule adopts the interim final rule (IFR) published at 67 
FR 72726 on December 6, 2002, as a final rule with changes. The 
provisions of the IFR became effective on December 8, 2003. The rule 
resulted from requirements placed on the FAA by the Aging Aircraft 
Safety Act (AASA) of 1991. Section 402 of the AASA requires the 
Administrator to ``initiate a rulemaking proceeding for the purpose of 
issuing a rule to assure the continuing airworthiness of aging 
aircraft.''
    Specifically, the AASA requires ``the Administrator to make such 
inspections and conduct such reviews of maintenance and other records 
of each aircraft used by an air carrier to provide air transportation 
as may be necessary to determine that such is in a safe condition and 
is properly maintained for operation in air transportation.'' Further, 
the AASA states an air carrier must show, as part of the inspection, 
``that maintenance of the aircraft's structure, skin, and other age-
sensitive parts and components have been adequate and timely enough to 
ensure the highest degree of safety.'' Title 14, Code of Federal 
Regulations (14 CFR) Sec. Sec.  121.368, 129.33, 135.422, and 135.423 
of the IFR cover the AASA's requirements for airplane inspections and 
records reviews.
    Additionally, the FAA found it necessary to initiate a consistent 
approach to preserve the continued airworthiness of the airplane 
structure that is susceptible to fatigue cracking that could contribute 
to a catastrophic failure. Sections 121.370a, 129.16, and 135.168 of 
the IFR include supplemental inspection requirements that address the 
continued airworthiness of this type of airplane structure. These 
sections require operators to use damage-tolerance-based inspections 
and procedures to maintain the continued airworthiness of the affected 
airplane structure. However, certain operators of airplanes initially 
certificated with nine or fewer passenger seats and used in scheduled 
operations could use service-history-

[[Page 5519]]

based inspections to meet these requirements. The damage-tolerance (DT) 
based inspections and procedures required in these sections are based 
on the same methodology identified in 14 CFR 25.571 (Damage-tolerance 
and fatigue evaluation of structure). This methodology has been used 
successfully to develop supplemental structural inspection programs 
(SSIP) and repair assessment guidelines (RAGs) for pressurized 
fuselages. Therefore, the FAA has determined that this methodology is 
an acceptable approach to maintaining the continued airworthiness of 
the affected airplane structure.

IFR Revised by Technical Amendment

    The FAA published a technical amendment (68 FR 69307) on December 
12, 2003, to the Aging Airplane Safety IFR. This amendment made minor 
technical changes to the IFR.

Aging Airplane Program Activities

    The FAA's Aging Airplane Program came about to address airplanes 
operated beyond their original design service goals, the 1988 Aloha B-
737 accident, and the Aging Aircraft Safety Act of 1991. When the 
program first started, the goal was to preserve the structural 
integrity of the aging airplane fleet by requiring structural 
modifications and inspections to address certain design deficiencies 
that could lead to airplane structural damage. Following the 1996 TWA 
800 B-747 accident, the FAA expanded the Aging Airplane Program to 
include non-structural systems. The goal was to address requirements 
for design, inspection, repair, and maintenance of fuel tanks and 
electrical wiring on aging airplanes. Efforts related to Aging Airplane 
Program initiatives have resulted in the issuance of airworthiness 
directives (ADs) and rulemaking actions. Such actions include this 
Aging Airplane Safety rule, which addresses airplane structure.

The FAA's Review of the Aging Airplane Program

    Because of issues raised by industry about the effectiveness and 
efficiency of the Aging Airplane Program, the FAA recently performed a 
comprehensive review of it. The goals of this review were to--
     Identify how to most effectively align rulemaking 
initiatives to ensure there are no overlapping or redundant 
requirements;
     Ensure that design approval holder data supporting 
operator compliance are available and timely; and,
     Ensure the resulting maintenance requirements allow 
operators to be more efficient in revising their maintenance programs 
when addressing multiple, similar initiatives.
    The Aging Airplane Safety IFR was among the rules and proposals 
included in the FAA's aging program review. The FAA determined that 
better aligning certain compliance dates in existing rules and pending 
proposals and making certain substantive changes to them would increase 
their cost-effectiveness without compromising safety. As a result, the 
FAA has made changes to the Aging Airplane Safety IFR and has clarified 
parts of the rule language in the IFR. Also, the FAA has made changes 
to other aging program rules.
    Additionally, the FAA tasked the Aviation Rulemaking Advisory 
Committee (ARAC) to develop damage tolerance (DT) guidelines to support 
compliance with Sec. Sec.  121.370a and 129.16 of the Aging Airplane 
Safety rule in response to comments to the IFR (69 FR 26641, May 13, 
2004). Further, based on comments to the IFR, the FAA is considering 
proposing a new rule to require type certificate and supplemental type 
certificate holders to develop DT programs that will support compliance 
with the Aging Airplane Safety final rule.
    On July 30, 2004, the FAA published a final rule with request for 
comments entitled, Fuel Tank Safety Compliance Extension and Aging 
Airplane Program Update, (69 FR 45936). You may refer to that document 
for more details about the FAA's review of the Aging Airplane Program 
initiatives and the results of the review.

Changes to the IFR

    Based on the FAA's recent review of the Aging Airplane Program and 
the comments to the Aging Airplane Safety IFR, we believe certain 
revisions and clarifications to the IFR are proper. These changes are 
intended to retain the rule's safety objective while reducing the 
burden on the industry. The major changes, which pertain to the 
supplemental inspections requirements in Sec. Sec.  121.370a, 129.16, 
and 135.168 are listed below and are described in detail later in this 
preamble.
     Removal of certain DT-based supplemental inspection 
requirements for airplanes operated under parts 121 and 129.
     Extension of the compliance date and narrowing of the 
airplane applicability for the DT-based supplemental inspection 
requirements that remain in the final rule for airplanes operated under 
parts 121 and 129.
     Removal of the supplemental inspection requirements for 
part 135 airplanes.
     Clarification of the type of airplane structure the 
supplemental inspection requirements cover.

Discussion of Comments

    The FAA sought and received comments to the interim final rule 
(IFR).

General Comments

    Comment: Several commenters express concern the FAA did not seek 
recommendations from the ARAC to develop the IFR. The commenters ask 
the FAA to explain why the agency did not seek ARAC's advice. One 
commenter wants the FAA to refer the IFR to the ARAC for final review 
and completion so the rule could more easily be harmonized with foreign 
Civil Aviation Authorities' (CAAs) requirements.
    FAA Response: This final rule is based on a congressional mandate 
imposed by the Aging Aircraft Safety Act (AASA) of 1991. Therefore, 
rather than seeking recommendations, the FAA used the terms of the AASA 
to develop the Aging Airplane Safety rule. However, based on requests 
from the Air Transport Association (ATA) and others from the industry, 
the FAA recently tasked ARAC (69 FR 26641, May 13, 2004) to develop 
guidelines that would support industry's compliance with Sec. Sec.  
121.370a and 129.16 of this final rule. Since Congress mandated the 
terms of the Aging Airplane Safety rule, the FAA believes it would not 
have been proper to refer the rule to ARAC, solely to harmonize it with 
foreign CAAs' actions.

Airplane Inspections and Records Reviews

    Comment: A commenter suggests the FAA modify the recordkeeping 
requirements of the IFR.
    FAA Response: The commenter did not provide specific 
recommendations about how to modify the recordkeeping requirements of 
the rule. However, as part of the FAA's review of the Aging Airplane 
Program, the FAA withdrew the Corrosion Prevention and Control Program 
(CPCP) proposed rule (69 FR 50350, August 16, 2004). Therefore, the FAA 
has amended the Aging Airplane Safety IFR to remove from Sec. Sec.  
121.368, 129.33, and 135.422, the requirement for operators to provide 
the current status of CPCPs as a separate item. Instead, they will 
provide this information as part of the requirement for the current 
inspection status of the airplane.

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However, for those CPCPs mandated by airworthiness directive (AD), they 
will provide it as part of the requirement for the current status of 
ADs.
    In addition, the FAA has removed the requirement from Sec. Sec.  
121.368, 129.33, and 135.422 of this final rule for operators to 
provide the current status of the inspections and procedures required 
under the supplemental inspection portion of the IFR. The FAA removed 
this requirement because under the terms of the final rule, operators 
must provide this information as part of the current inspection status 
of the airplane.
    Comment: One commenter requests the FAA include a definition for 
``age-sensitive parts'' in 14 CFR part 1.
    FAA Response: For purposes of this rule, the FAA considers this 
term to mean those structural parts and components that are susceptible 
to fatigue cracking that could contribute to a catastrophic failure. 
Although the FAA has not defined age-sensitive parts in 14 CFR part 1, 
we will include this definition in the related advisory material.
    Comment: One commenter requests the FAA amend the regulation to 
allow the use of Organizational Designated Airworthiness 
Representatives (ODAR) to perform the inspections and records review 
required by Sec.  121.368. Several commenters address the use of 
Designated Airworthiness Representatives (DARs) to perform the required 
inspections and records reviews. The commenters are concerned with 
access to enough inspectors to perform the necessary inspections. One 
commenter states that to carry out the required inspections and records 
review, every air carrier will need at least two or three DARs. The 
commenter says this would require a greater commitment by the FAA to 
qualify many more DARs than they have in the past. Another commenter 
states they would need access to a DAR or Principal Maintenance 
Inspector (PMI) in the FAA's London, United Kingdom, office to inspect 
their aircraft and review their records. The commenter requests the FAA 
clarify whether data obtained from this review would be acceptable to 
the FAA when transferring an aircraft to the U.S. registry.
    FAA Response: The FAA does not believe it is necessary to include 
specific language in the rule allowing the use of ODARs to perform 
inspections and records review. Each operator may decide, based on 
individual need, whether they will use designees or have the FAA 
perform the airplane inspections and records review this rule requires. 
The final rule does not mandate the use of DARs or ODARs. The 
Administrator already has the authority under Sec.  183.33 (Designated 
Airworthiness Representative) to designate certain persons or 
organizations to perform these functions.
    To aid the inspections by existing DARs, the FAA has updated the 
guidance material in FAA Order 8100.8B, Designee Management Handbook, 
and is providing workshops for its designees. The intent is to maximize 
the number of DARs available to conduct the inspections and records 
reviews. The FAA remains committed to the timely issuance of designee 
authorizations to properly qualified persons.
    The comment about whether ``data'' obtained during airplane 
inspections and records review would be acceptable when transferring an 
aircraft to the U.S. registry is unclear. For part 129 operators, this 
final rule only applies to U.S.-registered airplanes. If the commenter 
transfers a non-U.S.-registered airplane to the U.S. registry, the 
airplane would have to meet all FAA operational and certification 
requirements on transfer, including the requirements of this final 
rule.
    Comment: One commenter, who expresses concern for air safety, 
agrees the rule is needed and asks who would conduct the airplane 
inspections.
    FAA Response: The FAA's airworthiness inspectors and designees will 
conduct the airplane inspections and records reviews required by this 
rule.
    Comment: Two commenters discuss examining wire during airplane 
inspections and records reviews. One commenter says wiring is often 
overlooked in the inspection process. A second commenter says it is 
necessary to determine a timetable for wire and cable bundles to be 
inspected and replaced.
    FAA Response: Congress passed the Aging Aircraft Safety Act of 1991 
to address aging aircraft structural concerns resulting from the April 
1988 accident involving a B-737. The Aging Airplane Safety rule, which 
resulted from the Act, addresses only structural concerns. The FAA is 
evaluating future rulemaking actions that may address other airplane 
systems such as wiring.
    Comment: Some commenters say the rule is unnecessary. Several 
commenters believe the rule does not provide added safety benefits. One 
commenter says the FAA can achieve the same results without rulemaking 
by simply adding increased inspections to C and D checks. One commenter 
says the IFR duplicates existing regulations, is unevenly applied, and 
is inconvenient.
    FAA Response: The Aging Aircraft Safety Act (AASA) of 1991, as 
codified in Section 44717 of Title 49 U.S.C., directs the Administrator 
to ``make inspections and review the maintenance and other records of 
each aircraft an air carrier uses to provide air transportation.'' The 
FAA issued this rule to comply with this statutory mandate. The rule 
helps ensure the continued structural airworthiness of airplanes that 
operate beyond their original design service goals. The inspection and 
records review requirements in this rule are not intended to increase 
the number of inspections the operator performs. The FAA will perform 
the airplane inspections and records reviews required by this rule 
during scheduled maintenance.
    Comment: Some commenters express concern the term ``highest degree 
of safety'' is vague and is open to interpretation. One commenter says 
while this term appears in the Federal Aviation Act of 1958, it has 
never appeared in a rule until now. The commenter believes the FAA 
should interpret the Act rather than simply repeat the phrase in the 
rule.
    FAA Response: The FAA's use of the term, ``highest degree of 
safety,'' in the Aging Airplane Safety rule is based on the statutory 
language contained in the AASA of 1991, subsequently codified as 
section 44717 of title 49 U.S.C. For purposes of this rule, the FAA 
considers that operators will have met the ``highest degree of safety'' 
by complying with their FAA-approved maintenance program.
    The maintenance programs for those airplanes affected by the 
inspections and records review requirement of this rule may include 
certain elements of the FAA's Aging Airplane Program listed below:
     Supplemental Structural Inspection Programs.
     Corrosion Prevention and Control Programs.
     Structural Modification Programs.
     Repair Assessment Programs.
     Inspections and procedures identified in the Airworthiness 
Limitation section of the Instructions for Continued Airworthiness.
     Damage-tolerance-based inspections and procedures required 
by Sec. Sec.  121.370a and 129.16 of this rule.
    The first five elements have been incorporated into most large 
transport category airplane maintenance programs. There are some 
airplanes subject to the inspections and records reviews requirement 
that do not include

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some of these elements. Maintenance programs that include any of these 
elements will be subject to the airplane inspections and records review 
provisions of this rule.
    According to the IFR, operators of certain model airplanes are not 
required to incorporate damage-tolerance-based inspections and 
procedures in their maintenance programs until December 5, 2007. This 
final rule extends this compliance date to December 20, 2010. As a 
result, damage-tolerance-based inspections and procedures, as required 
by Sec. Sec.  121.370a and 129.16, are not required to be incorporated 
into maintenance programs before this date.
    As explained later in this preamble under ``Changes to the Interim 
Final Rule'' heading, the FAA has removed the DT requirements for 
certain airplanes operated under parts 121, 129, and 135. However, the 
airplane inspections and records review requirement still applies to 
these airplanes.
    Comment: One commenter states the requirements for the extent of 
inspections and records reviews are not clearly defined, which may lead 
to inconsistent interpretation and application.
    FAA Response: The FAA intends to perform structural spot 
inspections of each airplane and review those records needed to 
determine compliance with Sec. Sec.  121.368(d), 129.33(c), 135.422(d) 
of this final rule. The FAA has provided the following guidance to aid 
compliance with the airplane inspections and records reviews 
requirements in the rule:
     Notice 8300.113, Conducting Records Reviews and Aircraft 
Inspections Mandated by the Aging Aircraft Rules, dated November 25, 
2003, which has been incorporated into FAA Order 8300.10, Airworthiness 
Inspector's Handbook. This guidance includes information on scheduling 
inspections and records review to minimize the impact on operators' 
maintenance schedules.
     Advisory Circular (AC 120-84) Aging Airplane Inspections 
and Records Reviews, provides guidance for operators to comply with the 
requirements of this rule.
    The FAA believes providing guidance for our inspectors and for the 
industry will help reduce inconsistencies in interpreting and complying 
with the rule.
    Comment: A commenter recommends the records review of ADs and 
modifications on structures that are not easily ``de-modified,'' such 
as Boeing 747 section 41, be waived after the first inspection. For 
repetitive inspections, the commenter suggests the review be required 
only on the records collected since the last inspection.
    FAA Response: Under the airplane inspections and records review 
requirements, the FAA does not intend to inspect an airplane such that 
an operator would have to ``de-modify'' the structure to gain access to 
certain areas. These areas include ones modified by AD, supplemental 
type certificate (STC), FAA approved service bulletin, or FAA approved 
repair. However, if in complying with Sec. Sec.  121.370a and 129.16 
deficiencies are identified in a repair, alteration, or modification, 
or in the inspection procedures, removal of a previously modified 
structure may be required.
    Comment: A commenter says the FAA's Flight Standards office has for 
many years conducted thorough records reviews and on-site spot 
inspections of airplanes during heavy maintenance visits. The commenter 
wants the FAA to allow credit for these prior records reviews and 
inspections either in the regulation or in the guidance material. The 
commenter says a certificate holder's PMI could be responsible for 
determining the extent of credit to give on a particular airplane.
    FAA Response: Operators must provide the FAA with the current 
inspection status of the airplane as required by Sec. Sec.  121.368(d), 
129.33(c), and 135.422(d). To meet the requirement of these sections, 
the FAA intends to conduct the specified inspections and records review 
during scheduled maintenance visits. The FAA also intends to perform 
structural spot inspections of each airplane and review those records 
necessary to determine compliance with this rule. The FAA will consider 
the scope and timeframe of prior inspections to determine the extent to 
which those prior inspections can help the operator meet the 
inspections and records reviews mandated by this rule.
    Comment: One commenter believes the requirement for a fixed repeat 
inspection interval not to exceed 7 years required by Sec.  121.368(b) 
should be removed. Further, any subsequent inspection requirements 
should be met based on an agreement between the operator and the PMI. 
This would allow the operator and the PMI to agree on the schedule for 
follow-up inspections. The commenter says this is particularly true for 
those fleet types where the FAA-approved maintenance programs are 
segmented. Such programs do not provide for 14-day downtimes or only 
provide for 14-day downtimes at intervals beyond 7 years. Thus, the 
commenter recommends the following wording at the end of subparagraphs 
(1), (2), and (3) of Sec.  121.368(b): ``* * * and thereafter at 
intervals approved by the FAA principal maintenance inspector (PMI) 
having cognizance for the operator.''
    FAA Response: The FAA selected a 7-year interval for repeat 
inspections to provide time for operators to schedule the inspections 
and records review. Such scheduling would take place during a ``C'' 
check or segment thereof, ``D'' check or segment thereof, or other 
scheduled maintenance visits where structural inspections are done. The 
FAA believes a 7-year repeat interval provides scheduling flexibility 
for the operator to meet the requirements of the rule. Also, Sec. Sec.  
121.368(c), 129.33(b), and 135.422(c) of the rule authorize the 
Administrator to approve up to a 90-day extension beyond the 7-year 
interval required by Sec. Sec.  121.368(b), 129.33(a), and 135.422(b). 
The FAA's PMI may approve this extension for the Administrator. The FAA 
agrees the operator and PMI should work together to agree on the 
specific time within the 7-year repeat intervals to conduct the 
required inspections and records review.
    Comment: Several commenters express concern about the inspection 
intervals. One commenter states the repeat interval for inspections 
will result in maintenance program scheduling constraints. The 
commenter says meeting the 7-year requirement in the rule would result 
in 118 added heavy maintenance visits (HMV) because their HMVs on B-737 
and B-767s are scheduled at 8-year intervals. In general, the commenter 
believes the timeframes for inspections and records reviews in the rule 
are out of sync with their particular maintenance program requirements. 
Another commenter states that certificate holders and FAA inspectors 
should work together to schedule the required inspections to coincide 
with existing inspection schedules. The commenter adds the FAA should 
quickly publish guidance that removes any doubt about the effect of the 
rule on heavy maintenance check (HMC) schedules.
    FAA Response: The AASA states the records reviews and inspections 
will be carried out as part of the operator's HMC. To comply with the 
statute, the FAA considers an HMV or HMC to consist of a ``C'' check or 
segment thereof, a ``D'' check or segment thereof, or other scheduled 
maintenance where structural inspections are accomplished. The FAA 
agrees the required inspections and records review should coincide as 
much as possible with operators' existing maintenance

[[Page 5522]]

schedules. The FAA does not believe the rule will result in added HMVs 
or HMCs since the FAA intends to coordinate the airplane inspections 
and records reviews to coincide with scheduled HMVs and HMCs. To 
provide guidance for the conduct of the inspections and records 
reviews, the FAA published Notice 8300.113 and AC 120-84, discussed 
earlier in this preamble.
    Comments: A commenter suggests the FAA reduce the inspection 
intervals from 14 years to 8 years and conduct periodic spot checks of 
20 percent of the airplanes during the inspection intervals.
    FAA Response: The statute requires inspections and records reviews 
of each airplane to ``be carried out as part of each HMC of the 
aircraft conducted after the 14th year in which the aircraft has been 
in service.'' To meet this requirement, the FAA must inspect each 
airplane. However, the FAA intends to conduct a spot inspection of each 
airplane. The FAA established the first and repeat intervals at which 
inspections and records reviews will be done. The FAA set the first 
inspections based on the age of the airplane with the oldest airplanes 
being scheduled first. The repeat intervals for all airplanes, 
regardless of age, is set at 7 years, following completion of the first 
inspection.
    Comment: One commenter believes Sec.  121.368(d) should request a 
listing of operational limits as part of the airplane records. This 
commenter also says aging aircraft rules require full compliance with 
their terms on transfer of an aircraft. Therefore, a statement about 
full compliance on transfer should be included in the rule.
    FAA Response: The FAA does not require a listing of ``operational 
limits'' as part of the airplane records required in Sec.  121.368. 
However, the FAA does require that operators make available records 
that contain the current status of life-limited parts of the airframe.
    The FAA has not included a requirement that an operator provide a 
statement that an airplane complies with the provisions of this rule at 
the time of transfer. Operators show compliance with the airplane and 
records availability requirements of the rule by making affected 
airplanes that meet the stated time in service and their associated 
records available to the Administrator within the prescribed interval. 
If the commenter transfers an airplane from a foreign country to the 
U.S. registry, the airplane will have to meet all FAA operational and 
certification requirements on transfer, including the requirements of 
this final rule.
    Comments: Several commenters state Sec.  121.368 duplicates current 
regulations, especially the provisions of Sec.  121.380, which also 
relate to recordkeeping requirements. In support of their comments, 
they say most operators of large transport category airplanes have 
developed elaborate maintenance recordkeeping systems under Sec.  
121.380. They say these systems duplicate the requirements under Sec.  
121.368. They recommend the FAA revise the language in Sec.  121.368(d) 
that states ``* * * together with records containing the following 
information'' to read ``* * * together with the following records or 
those specified in Sec.  121.380.''
    One commenter contends the FAA should modify the rule or add in the 
advisory circulars a statement saying compliance with Sec.  121.380 is 
an alternate way to comply with Sec.  121.368. This same commenter 
states Sec.  121.380 is more comprehensive than Sec.  121.368, 
especially about airworthiness directives. Existing Sec.  
121.380(a)(2)(vi) requires records to include ``* * * the current 
status of applicable airworthiness directives, including the date and 
methods of compliance, and, if the airworthiness directive involves 
recurring action, the time and date when the next action is required.'' 
However, for Airworthiness Directives, Sec.  121.368(d)(8)(i) requires 
``current status of the following, including the method of 
compliance.''
    FAA Response: The FAA agrees that some of the recordkeeping 
requirements of Sec.  121.368(d) are also found in Sec.  121.380. 
However, Sec.  121.368(d) contains added recordkeeping requirements not 
found in Sec.  121.380. These added requirements allow the FAA to 
determine compliance with the Aging Airplane Safety rule. For example, 
Sec.  121.368(d) requires records containing information on total years 
in service of the airplane and total flight cycles of the airframe. 
Because Sec.  121.368(d) contains requirements not contained in Sec.  
121.380, compliance with Sec.  121.380 by itself cannot constitute 
compliance with Sec.  121.368(d). Operators can show compliance to both 
Sec. Sec.  121.368(d) and 121.380 within a single recordkeeping system 
that is acceptable to the FAA. This removes the need to repeat 
recordkeeping for those requirements found in Sec.  121.368(d) and 
Sec.  121.380. The FAA included guidance in advisory circular AC 120-
84, Aging Airplane Inspections and Records Reviews, to address the 
records requirements. The FAA also has included guidance in Notice 
8300.113, Conducting Records Reviews and Aircraft Inspections Mandated 
by the Aging Aircraft Rules, which has recently been incorporated into 
FAA Order 8300.10 to address these requirements.
    The FAA agrees that compliance with Sec.  121.380(a)(2)(vi) should 
satisfy the recordkeeping requirements contained in Sec.  
121.368(d)(8). Therefore, we have revised Sec.  121.368(d)(8) to match 
the requirements in Sec.  121.380(a)(2)(vi).
    Comments: A commenter says the provisions of Sec.  119.59 already 
provide adequate authority to carry out aircraft inspections and 
records reviews required by Sec.  121.368.
    FAA Response: The FAA agrees. Section 119.59(a) states ``at any 
time or place, the Administrator may conduct an inspection or test to 
determine whether a certificate holder under this part is complying 
with Title 49 of the United States Code, applicable regulations, the 
certificate, or certificate holder's operations specifications.'' The 
Aging Aircraft Safety Act, however, requires the Administrator to 
conduct specific inspections that before the Act were part of the FAA's 
discretionary oversight.
    Comments: One commenter notes some major repairs have no repetitive 
inspections associated with them and recommends the FAA amend Sec.  
121.368(d)(10) to read: ``A report of major repairs which require 
supplemental inspections, and the inspection status of those repairs.''
    FAA Response: The FAA disagrees. Knowing the inspection status of 
all major repairs, including those repairs that have no damage-
tolerance-based repetitive inspection requirement, is an important part 
of maintaining the continued airworthiness of aging airplanes. The 
inspection and records review required by Sec.  121.368(d)(10) will 
help ensure major repairs and changes to major repairs are properly 
recorded and their inspection status verified. There are past instances 
where modification of major repairs degraded the airplane's structural 
integrity to the point of making it no longer airworthy. In some cases, 
it was determined the current inspections were not adequate to address 
the modifications. In other cases, where no inspections were required 
for the original modification, it was determined that repetitive 
inspections were necessary to ensure the airworthiness of the modified 
repair. Therefore, the value of the inspection and records review 
required by Sec.  121.368(d)(10) is to verify the condition of all 
major repairs and identify areas where more inspections may be 
required.

[[Page 5523]]

Advisory Material and Training for Aging Airplane Inspections and 
Records Reviews

    Comment: Several commenters express concern about whether enough 
training, guidance material, and trained inspectors would be available 
to support compliance with the rule. One commenter suggests if guidance 
materials and trained inspectors are not ready by December 8, 2003, the 
compliance date specified in Sec.  121.368, the FAA should index the 
48-month inspection and records review completion window based on the 
availability of trained inspectors. One commenter requests the FAA open 
DAR and PMI training programs to non-U.S. operators. Another commenter 
asks the FAA to extend this compliance date to the date the FAA 
completes training for FAA inspectors and DARs, unless the guidance 
material is issued with the final rule. One commenter says it is 
especially important to provide training and guidance material to 
operators during the initial period of compliance with this rule.
    FAA Response: The FAA agrees that timeliness of training is 
important to meeting the deadlines in the rule. Therefore, the FAA 
completed workshops for its flight standards airworthiness inspectors 
and is providing workshops for its designees (DARs and ODARs). The 
intent of these workshops is to ensure that FAA airworthiness 
inspectors, DARs, and ODARs use uniform procedures when conducting 
their inspections and records reviews. A foreign air carrier may hire 
an FAA designee to perform the airplane inspections and records review 
required by the Aging Airplane Safety rule. The FAA does not intend to 
develop a training course specifically for air carriers. However, the 
FAA has developed an AC 120-84, Aging Airplane Inspections and Records 
Reviews, to help operators affected by the Aging Airplane Safety rule.
    Additionally, the FAA published guidance in Notice 8300.113, 
Conducting Records Reviews and Aircraft Inspections Mandated by the 
Aging Aircraft Rules. The FAA's training preparations and published 
guidance allowed the FAA to begin inspections and records reviews 
shortly after the effective date of the IFR.
    The FAA is adopting an approach that enables the existing FAA 
inspector workforce to comply with their obligations under this rule. 
The approach involves the use of spot inspections and records reviews 
and coordinating with operators to perform these inspections and 
reviews during scheduled maintenance.
    Comment: A commenter requests clarification on the applicability of 
Handbook 8300.10, volume 3, chapter 2, to on-site inspections.
    FAA Response: The FAA has reviewed volume 3, chapter 2 of FAA Order 
8300.10, Airworthiness Inspector's Handbook, which discusses the 
conduct of structural spot inspections of an operator's aircraft, to 
determine the applicability of that chapter to the airplane inspections 
and records review requirements. The FAA found that this Order did not 
provide enough guidance to conduct inspections and record reviews 
required under the rule. Therefore, the FAA issued Notice 8300.113 on 
November 25, 2003, to provide added guidance to inspectors to conduct 
these inspections and records reviews.
    Comment: Several commenters discuss draft AC 120-84, which was 
released concurrently with the IFR. In general, the commenters express 
concern that the AC provides no added guidance to operators. The 
commenters feel that operators are inadequately prepared for the 
inspections and reviews required under the IFR.
    FAA Response: Based on comments received, the FAA has revised AC 
120-84, Aging Airplane Inspections and Records Reviews, to be 
consistent with the final rule. The FAA has provided more guidance in 
the AC on conducting airplane inspections and records reviews. In 
addition, the FAA has changed Order 8300.10, Airworthiness Inspector's 
Handbook, to provide standardized guidance to FAA inspectors when 
conducting airplane inspections and records reviews.
    Comment: A commenter requests the FAA clarify whether AC 120-84 is 
intended to address structural issues only.
    FAA Response: AC 120-84 applies to airplane structures only.
    Comment: A commenter notes that AC 120-84 contains an inaccurate 
reference to Sec.  121.212, which does not exist.
    FAA Response: The FAA agrees with the commenter and has made the 
correction in the final version of AC 120-84.

Supplemental Inspections

    To aid understanding of the discussion about repairs, alterations, 
and modifications (RAMs), which appears below, the FAA offers the 
following explanation: The industry has used the terms ``alteration'' 
or ``modification'' synonymously to define a design change to an 
airplane. Therefore, the FAA uses both terms to avoid potential 
misinterpretation of the intent of these terms.
    Comment: A commenter suggests the FAA withdraw the supplemental 
inspection requirement and task the ARAC to provide advice in this 
area. Another commenter suggests the FAA extend the compliance date to 
2010 since the FAA issued the notice of proposed rulemaking in 1999.
    FAA Response: The FAA determined that it is no longer necessary to 
impose the DT requirements of this rule on the number of airplanes 
mandated in the IFR. Therefore, this final rule only imposes DT 
requirements on airplanes that are--
     Transport category;
     Turbine powered;
     Have a type certificate issued after January 1, 1958; and
     Have, because of original type certification or later 
increase in capacity, a maximum type-certificated passenger seating 
capacity of 30 or more or a maximum payload capacity of 7500 pounds or 
more.
    The FAA determined that damage-tolerance-based inspections and 
procedures are an effective way to meet the AASA's requirement for 
preserving the continued airworthiness of an airplane's structure. AC-
25.571-1C, Damage Tolerance and Fatigue Evaluation of Structure, which 
the ARAC helped develop, is an acceptable means of compliance with the 
DT-based supplemental inspection requirements for the baseline 
structure (type design) of an airplane. The FAA tasked the ARAC on May 
13, 2004, to develop guidelines to support the industry's compliance 
with the rule's requirements to address repairs, alterations, and 
modifications. Further, the FAA has extended the compliance date for 
operators to have damage-tolerance-based inspections and procedures in 
their airplane maintenance programs from December 5, 2007, to December 
20, 2010. This extension should allow enough time for the ARAC to 
perform the tasking and for operators to comply with the supplemental 
inspection requirements of the final rule.
    Comment: A commenter asks whether the FAA would extend the December 
20, 2010, compliance date for those parts of the IFR that already 
contain this compliance date.
    FAA Response: The FAA has removed from the rule the supplemental 
inspection requirements related to design-life goal airplanes, 
airworthiness directive-mandated service-history-based inspections, and 
multiengine airplanes with nine or fewer passenger seats. These 
requirements had a

[[Page 5524]]

compliance date of December 20, 2010. However, as noted earlier, the 
FAA has removed all part 135 supplemental inspection requirements from 
this rule. Also, the FAA has extended the compliance date for the 
remaining supplemental inspection requirements under parts 121 and 129 
from December 5, 2007, to December 20, 2010.
    Comment: One commenter states for aircraft transferring from 
country to country, it is not clear how the life limits (design-life 
goal) would be interpreted.
    FAA Response: As noted earlier, the FAA has removed the design life 
goal requirement from the rule.
    Comment: One commenter states the FAA has not proven that a DT 
inspection program is any more effective than the current programs 
operators use for their small airplane fleets. The commenter suggests 
the FAA use another method for 10- to 19-seat, nontransport-category 
airplanes.
    FAA Response: Based on industry comments and the FAA's reassessment 
of the IFR and the Aging Airplane Program, the FAA narrowed the scope 
of airplane applicability in Sec. Sec.  121.370a and 129.16 to impose 
DT requirements on transport category, turbine powered airplanes with a 
type certificate issued after January 1, 1958, that as a result of 
original type certification or later increase in capacity, have--
     A maximum type-certificated passenger seating capacity of 
30 or more; or
     A maximum payload capacity of 7,500 pounds or more.
    As a result, the final rule does not apply to the airplanes the 
commenter references.
    Comment: A commenter notes that currently DT and safe-life 
inspections are acceptable to show compliance with maintenance 
requirements. However, it appears that under the IFR, the FAA will only 
accept DT-based maintenance programs after December 2007. The commenter 
suggests the IFR clearly state that parts certified as safe-life are 
exempt from the requirements of Sec.  121.370a. Another commenter notes 
that several aircraft, such as the EMB-110, were designed using safe-
life criteria, which were required at the time of certification. The 
commenter states that aircraft not designed using DT techniques will 
not have accessibility to all areas that must be inspected under a 
Damage Tolerance Inspection Program (DTIP). The commenter suggests that 
forcing DT inspections could result in unintended damage to the 
structural integrity of the aircraft.
    FAA Response: The intent of the Aging Airplane Safety rule is to 
apply the DT and fatigue evaluation of structure consistent with the 
evaluation prescribed in Sec.  25.571. Section 25.571(c) includes 
provisions for the evaluation of safe-life structures when the 
applicant determines the DT requirements of Sec.  25.571(b) are 
impractical for a particular structure. For purposes of this rule, 
damage-tolerance-based inspections and procedures will not be required 
for an airplane component certified as a safe-life design (e.g., 
landing gear) and where the application of the DT requirements of Sec.  
25.571(b) are determined to be impractical.
    Comment: Several commenters ask the FAA to clarify the extent to 
which a DT assessment for repairs, alterations, and modifications 
(RAMs) beyond the fuselage pressure boundary will be required. One of 
the commenters says the industry held 29 meetings over 7 years to 
develop a process and procedure to assess existing repairs. They found 
that a rational, technical basis is needed only to assess the DT of 
fuselage pressure boundary repairs. Also, the commenter states while 
the IFR indicates damage-tolerance-based maintenance programs must be 
in place by December 2007, the IFR does not say what this means. The 
commenter recommends two options regarding Sec.  121.370a. In option 1, 
the commenter states the FAA should withdraw Sec.  121.370a and the 
associated draft AC 91-56B (regarding airplanes >75,000 lbs maximum 
takeoff weight (MTOW)). Additionally, the commenter requests that the 
FAA task the Aviation Rulemaking Advisory Committee (ARAC) with 
formulating the technical considerations and the rule and advisory 
language for developing a damage tolerance-based maintenance program 
for the primary structure of the airplane. In option 2, the commenter 
notes the FAA should remove the DT assessment of primary structural 
elements (PSEs) for RAMs discussion from the preamble to the IFR and 
the associated draft AC 91-56B, when re-published, and task ARAC to 
develop appropriate direction for the FAA.
    One commenter also notes that significant gaps appear in the DT 
guidance materials original equipment manufacturers (OEM) provide for 
DT-based inspections and procedures.
    Another commenter states the rule, with respect to RAMs made to 
non-ATA 53 (fuselage structure) PSEs, should not apply to aircraft 
certificated before amendment 25-45. The commenter further states that 
they are unaware of any fleet evidence of DT problems associated with a 
repair to non-ATA 53 PSEs. The commenter supports the ARAC's 
Airworthiness Assurance Working Group's (AAWG) earlier recommendation 
on repair assessment that the scope of addressing repairs for DT on 
pre-amendment 25-45 aircraft should be confined to those repairs made 
only to the fuselage pressure boundary.
    FAA Response: In 1992, the FAA and the AAWG surveyed large 
transport category airplane models to assess the status of repairs. In 
1994, the AAWG requested manufacturers conduct a second survey on 
airplane repairs to validate the 1992 results. The surveys showed that 
the fuselage pressure boundary was the area most susceptible to 
structural damage and subsequent repairs. Therefore, in response to the 
AAWG's recommendations, the FAA issued the ``Repair Assessment for 
Pressurized Fuselages'' final rule (65 FR 24108, April 25, 2000).
    In the preamble language to that rule, the FAA recognized, based on 
the AAWG's recommendations, that additional rulemaking may be needed to 
address repairs on the remaining primary structures. In addition, the 
preamble under the heading ``Determining which Airplanes Should be 
Affected,'' states:

    Those transport category airplanes that have been certificated 
to regulatory standards that include the requirements for damage-
tolerance structure under Sec.  25.571 are not included in this 
rulemaking action. These later requirements make it incumbent on the 
operating certificate holder to return the structure to the original 
certification basis by installing only those repairs that meet the 
airplane's damage-tolerance certification basis. The AAWG, in its 
final report on this subject, did recommend continued monitoring of 
repairs on newer airplanes, with the possibility of additional 
rulemaking if conditions warrant * * * It was from this activity 
that the AAWG and the manufacturers recognized not only the need for 
a RAG document for each affected model, but a SRM updated to include 
the results of a damage-tolerance assessment.

    As transport category airplanes continue to accumulate flight 
hours, they are increasingly susceptible to fatigue cracking and 
repairs. The FAA has determined that there is no technical basis for 
excluding any repaired airplane structure that is susceptible to 
fatigue cracking that could contribute to a catastrophic failure. 
Therefore, the FAA believes that repairs made to such structure that is 
outside the pressure boundary must be addressed as part of this final 
rule.
    In an effort to support industry's compliance with the Aging 
Airplane Safety final rule, the FAA tasked ARAC (69 FR 26641, May 13, 
2004) to make recommendations regarding the assessment of repairs 
beyond the

[[Page 5525]]

fuselage pressure boundary. We tasked ARAC to complete their work by 
December 18, 2009. In addition, the FAA recognizes that additional time 
is needed to implement the ARAC recommendations, which are related to 
guidelines for establishing DT-based inspections and procedures for 
RAMs, and for operators to incorporate DT-based inspections and 
procedures for RAMs into their maintenance programs. Therefore, the FAA 
has extended the DT-based supplemental inspection requirement 
compliance time in this final rule to December 20, 2010.
    Comment: A commenter requests clarification on whether the FAA 
would accept a SSID program developed by the OEM as an alternate means 
of compliance with the supplemental inspection requirements.
    FAA Response: The FAA will accept a SSID program for the baseline 
structure of an airplane developed by the OEM and approved by the FAA. 
If a SSID does not consider repairs, alterations, and modifications 
(RAMs), as required by this rule, the FAA would not accept it as a 
means to comply with this portion of the rule.
    Comment: One commenter notes that the IFR will apply to pre- and 
post-amendment 25-45 airplanes; however, the accompanying guidance 
materials do not provide guidance for post-amendment 25-45 airplanes. 
Another commenter says the FAA should apply the December 2007 
compliance date only to DTIPs for those areas where guidance materials 
have been developed.
    FAA Response: The FAA believes adequate guidance exists for 
developing DT-based supplemental structural inspections for post-
amendment 25-45 airplanes. The FAA recognizes that the guidance 
material for developing DT-based supplemental inspection programs that 
address repairs, alterations, and modifications may be inadequate to 
support compliance with this rule. Therefore, the FAA has tasked the 
ARAC to draft an advisory circular that contains guidance to support 
operators' compliance with Sec. Sec.  121.370a and 129.16 for all 
affected airplanes. This guidance will support compliance with the 
final rule for the DT-assessment of repairs, alterations, and 
modifications made to aircraft structure that is susceptible to fatigue 
cracking that could contribute to a catastrophic failure.
    The FAA also has decided to extend the compliance date for the DT-
based supplemental inspection requirement from December 5, 2007 to 
December 20, 2010. This will allow the ARAC enough time to develop the 
guidance material and will give the operators enough time to 
incorporate the DT requirements into their maintenance programs.
    Comment: One commenter states that because ``DTIP'' is not 
concisely defined, the FAA should include a definition of this term in 
14 CFR part 1. A second commenter expresses concern over the FAA's 
failure to clearly define ``DTIP.''
    FAA Response: The term ``damage-tolerance-based inspections and 
procedures'' or DTIP as used in this rule refers to the actions needed 
to achieve damage tolerance as defined in AC 25.571-1C, Damage 
Tolerance and Fatigue Evaluation of Structure.
    Comment: Several commenters express concern that operators will not 
be able to comply with the supplemental inspection requirements in the 
rule without data from the OEM. One commenter notes the IFR does not 
require OEMs to provide these data. This commenter suggests the FAA 
Transport Airplane Directorate standardize SSID ADs to aid industry 
compliance with DT-based inspections. Another commenter states they 
would not be able to comply with the rule because the manufacturer has 
not issued FAA-approved SSIDs for their airplane fleets.
    FAA Response: The FAA is considering proposing a new rule to 
require type certificate and supplemental type certificate holders to 
develop damage tolerance inspection programs that will support 
compliance with the Aging Airplane Safety final rule. The FAA 
recognizes the need to standardize SSID ADs to aid industry's 
compliance with DT-based inspections and procedures.
    Comment: One commenter notes that although the FAA has acknowledged 
difficulty in implementing ADs for structural repair manuals, the FAA 
does not present a solution to this problem in the IFR.
    FAA Response: It is not the FAA's intent to mandate structural 
repair manuals by issuing ADs. While the commenter's specific concern 
is unclear, the FAA notes that we issue ADs to address known unsafe 
conditions on aircraft. OEM produced structural repair manuals are a 
part of the Instructions for Continued Airworthiness, and are used in 
carrying out operators' maintenance programs.
    Comment: A number of commenters express concern about the design-
life goals contained in Appendix N to part 121, Appendix B to part 129, 
and Appendix G to part 135 of the IFR. The commenters say the FAA may 
have used inconsistent approaches for determining design-life goals and 
evaluating specific aircraft types.
    FAA Response: The FAA acknowledges the concerns the commenters 
express. The FAA has removed the design-life goal requirements, which 
include part 121 Appendix N, part 129 Appendix B, and part 135 Appendix 
G, from the regulation. The design-life goals were intended as a 
transition measure for those models listed in the appendices. The IFR 
required inspection programs to be in place by December 5, 2007 for 
airplanes above their design-life goals. For those airplanes that had 
not reached their design-life goal, inspection programs were not 
required until December 20, 2010. Since the compliance date for the 
damage tolerance requirements has been extended to December 20, 2010, 
this transition period is no longer needed. Additionally, only three of 
the models listed in the appendices meet the new airplane applicability 
requirement of this final rule, and these three models are no longer 
operated under part 121.
    Comment: One commenter states that under existing ADs and repair 
assessment guidelines for pressurized fuselages, the required repair 
assessments are linked to the number of flight cycles as a percentage 
of the design-life goal. The commenter recommends that for airplanes 
that have more than 14 years in service but relatively few flight 
cycles, the FAA should not require DT assessment of all repairs during 
the initial aging aircraft inspections.
    FAA Response: The FAA recognizes that current repair assessment 
guidelines for pressurized fuselages required by Sec.  121.370 are 
linked to the number of flight cycles as a percentage of the design-
life goal. The FAA has tasked ARAC to develop guidelines that would 
support the industry's compliance with Sec.  121.370a for repairs, 
alterations, and modifications made to the baseline primary structure. 
The FAA expects the new repair assessment guidelines will be consistent 
with those developed for Sec.  121.370. Also, the FAA has extended the 
compliance date for damage-tolerance-based inspections and procedures 
to December 20, 2010. This will give the ARAC enough time to complete 
its work.
    Comment: One commenter recommends the term ``primary structure'' be 
replaced with the term ``Principle Structural Elements.''
    FAA Response: The FAA disagrees the term ``primary structure'' 
should be replaced with the term ``Principle Structural Elements.'' 
This is mainly because of the different industry

[[Page 5526]]

interpretations for the term ``Principle Structural Elements.'' 
However, the FAA believes it would be helpful to clarify the intent of 
this rule regarding the type of primary structure that requires damage-
tolerance-based inspections and procedures. Therefore, the FAA provided 
this clarification in Sec. Sec.  121.370a and 129.16 of this rule. The 
revised language applies to ``airplane structure susceptible to fatigue 
cracking that could contribute to a catastrophic failure.''

Advisory Material for Supplemental Inspections

    Comment: Many commenters address the need for the FAA to provide 
more guidance material to assist operators in complying with the 
required DT-based inspections and procedures.
    FAA Response: Guidance material is available in AC 25.571C for 
developing DT-based inspections for an airplane's baseline primary 
structure. As noted earlier, the FAA has tasked the ARAC to develop 
guidance material the operators can use to support their compliance 
with Sec. Sec.  121.370a and 129.16 of this rule with respect to 
addressing repairs, alterations, and modifications.
    Comment: One commenter says draft AC 91-56, Continued Structural 
Integrity Program for Airplanes, states that widespread fatigue damage 
(WFD) will be the subject of a separate rulemaking. However, little 
detail is given about how service bulletin reviews and aging aircraft 
programs should be carried out. The commenter recommends the FAA 
include in AC 91-56 the text the European Aging Aircraft Working Group 
(EAAWG) presented to cover these points. Another commenter questions 
whether the statement ``cracks must be difficult to detect during 
regular maintenance'' shows that WFD should be evaluated. If so, the 
commenter suggests the FAA clarify in the AC the effects of such an 
evaluation in extending design-life goals.
    FAA Response: This rule does not include requirements for 
evaluating WFD. However, the FAA is considering future rulemaking that 
would address this topic. As a part of their tasking, the ARAC will 
review and make recommendations to the FAA on AC 91-56. Since the EAAWG 
is represented on the ARAC working group that is conducting the review, 
the FAA expects the views of the EAAWG would be considered.
    Comment: A commenter suggests the FAA include a sample DT-
assessment report in AC 91-56.
    FAA Response: The commenter does not indicate how a DT-assessment 
report would be used and does not provide enough information about the 
scope of such a report. Without this information, the FAA is unable to 
consider including a sample report in AC-91-56.
    Comment: One commenter questions whether the FAA will assign 
extended design-life goals to aircraft with SSIDs.
    FAA Response: The FAA has removed the design-life goal requirements 
from the final rule. Therefore, aircraft with SSIDs will not be subject 
to design-life goal requirements.
    Comment: A commenter recommends the FAA include in the AC not only 
those RAMs produced by type certificate (TC) holders, but also RAMs 
produced by non-TC holders through alternate means.
    FAA Response: The FAA has tasked the ARAC to assess the 
effectiveness of AC-91-56B to provide guidance to supplemental type 
certificate (STC) holders for developing damage-tolerance-based 
inspections and procedures for repairs, alterations, and modifications 
made to airplane structure that is susceptible to fatigue cracking that 
could contribute to a catastrophic failure. The ARAC will provide 
recommendations regarding the development of guidance for addressing 
RAMs.
    Comment: A commenter notes that AC 91-60, The Continued 
Airworthiness of Older Airplanes, is being used to guide operators in 
scheduled operations. The commenter recommends the FAA edit the list of 
components in AC 91-60 to consider them for inclusion in inspection 
programs and express them in more general terms.
    FAA Response: AC 91-60 addresses service-history-based inspections, 
which are typically applied to airplanes operated under part 135. As 
mentioned in the FAA's response to prior comments, the FAA has changed 
the airplane applicability in this final rule. Because of this change, 
the requirement in Sec.  135.168 related to service-history-based 
inspections and procedures has been removed from the rule. However, the 
FAA intends to issue a revised version of the related AC, AC 91-60, 
Continued Airworthiness of Older Airplanes, as guidance for part 135 
operators, who may still want to develop service-history-based 
inspections.
    Comment: A commenter notes the preamble to the IFR states that 
certain DT-based supplemental structural inspection programs (SSIPs) do 
not fully meet the requirements of the IFR, which apply to the complete 
primary structure. The commenter suggests the final rule or its 
accompanying ACs state that inspections and procedures in the 
Airworthiness Limitation section of the Instructions for Continued 
Airworthiness and the supplemental structural inspection document 
(SSID) satisfy the IFR for baseline structure.
    FAA Response: With respect to an airplane's baseline structure, 
FAA-approved DT-based supplemental structural inspection programs that 
address airplane baseline structure susceptible to fatigue cracking 
that could contribute to a catastrophic failure are considered an 
acceptable