[Federal Register Volume 65, Number 80 (Tuesday, April 25, 2000)]
[Rules and Regulations]
[Pages 24108-24127]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-10220]
[[Page 24108]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 91, 121, 125, and 129
[Docket No. 29104; Amendment Nos. 91-264, 121-275, 125-33 & 129-28]
RIN 2120-AF81
Repair Assessment for Pressurized Fuselages
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: This action requires operators of certain transport category
airplanes to incorporate repair assessment guidelines for the fuselage
pressure boundary into their FAA-approved maintenance or inspection
program. This action is the result of concern for the continued
operational safety of airplanes that are approaching or have exceeded
their design service goal. The purpose of the repair assessment
guidelines is to establish a damage-tolerance based supplement
inspection program for repairs to detect damage, which may develop in a
repaired area, before that damage degrades the load carrying capability
of the structure below the levels required by the applicable
airworthiness standards.
EFFECTIVE DATE: May 25, 2000.
FOR FURTHER INFORMATION CONTACT: Brent Bandley, Los Angeles Aircraft
Certification Office, Airframe Branch, ANM-120L, Transport Airplane
Directorate, Federal Aviation Administration, 3960 Paramount Boulevard,
Lakewood, California 90712-4137, telephone (562) 627-5237, fax (562)
627-5210.
SUPPLEMENTARY INFORMATION:
Availability of Final Rules
An electronic copy of this document may be downloaded using a modem
and suitable communications software from the FAA regulations section
of the FedWorld electronic bulletin board service (telephone: 703-321-
3339), or the Government Printing Office's (GPO's) electronic bulletin
board service (telephone: (202) 512-1661).
Internet users may reach the FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the (GPO) Federal Register web page at http://www.access.gpo.gov/nara for access to recently published rulemaking
documents.
Any person may obtain a copy of this document by submitting 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. Communications must identify the amendment or docket
number of this final rule.
Persons interested in being placed on a mailing list for future
rulemaking documents should request from the above office a copy of
Advisory Circular No. 11-2A, ``Notice of Proposed Rulemaking
Distribution System,'' which describes the application procedure.
Small Business Regulatory Enforcement Fairness Act
The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996, requires the FAA to comply with small entity requests for
information or advice about compliance with statutes and regulations
within our jurisdiction. Therefore, any small entity that has a
question regarding this document may contact their local FAA official
Internet users can find additional information on SBREFA on the FAA's
web page at http://faa.gov/avr/arm/sbrefa/htm and may send electronic
inquires to the following Internet address: [email protected].
Background
On December 22, 1998, the FAA issued Notice of Proposed Rulemaking
(NPRM) 97-16, which was published in the Federal Register on January 2,
1998 (98 FR 126). That NPRM proposed to prohibit the operation of
certain transport category airplanes (operated under 14 CFR parts 91,
121, 125, and 129) beyond a specified time, unless the operator of the
airplane incorporated FAA-approved ``repair assessment guidelines''
into its approved maintenance inspection program. The FAA provided a
period of 90 days for the public to submit input on the proposed rule.
On April 3, 1998 (63 FR 16452), the FAA reopened the period for public
comment for an additional 90 days. (A discussion of the comments
received in response to the NPRM appears below.)
The repair assessment guidelines, which are to be approved by the
FAA for each airplane model affected by this rule, contain:
A methodology for assessing the types of repairs
expected to be found in the fuselage pressure boundary (fuselage
skins, bulkhead webs, and door skin), and
Methods to determine the damage-tolerance
characteristics of the surveyed repairs.
Each of the guidelines contains repetitive repair inspection
intervals that are based on residual strength, crack growth, and
inspectability evaluations, and are closely compatible with typical
operator maintenance practices (i.e., C-checks, D-Checks, etc.).
In addition to this final rule, the FAA has developed an associated
advisory circular (AC), ``Repair Assessment of pressurized Fuselages.''
The AC provides guidance for operators of the affected transport
category airplanes on how to incorporate FAA-approved repair assessment
guidelines into their FAA-approved maintenanced or inspection program
as a means to comply with this final rule. Availability of the AC will
be announced in Federal Register in the near future.
Issues Prompting This Rulemaking Activity
In April 1988, a high-cycle transport airplane enroute from Hilo to
Honolulu, Hawaii, suffered major structural damage to its pressurized
fuselage during flight. This accident was attributed in part to the age
of the airplane involved. The economic benefit of operating certain
older technology airplanes has resulted in the operation of many such
airplanes beyond their previously projected retirement age. Because of
the problems revealed by the accident in Hawaii and the continued
operation of older airplanes, both the FAA and industry generally
agreed that increased attention needed to be focused on the aging fleet
and on maintaining its continued operational safety.
In June 1988, the FAA sponsored a conference on aging airplanes. As
a result of that conference, the FAA established a task force in August
1988 as a sub-group of the FAA's Research, Engineering, the Development
Advisory Committee, representing the interests of the aircraft
operators, aircraft manufacturers, regulatory authorities, and other
aviation representatives. The task force, then known as the
Airworthiness Assurance Task Force (AATF), set forth five major
elements of a program for each airplane model in the aging transport
fleet that would serve to keep the aging fleet safe:
Select service bulletins describing modificaitons and
inspections necessary to maintain structural integrity;
Develop inspection and prevention programs to address
corrosion;
Develop generic structural maintenance program
guidelines for aging airplanes;
Review and update the Supplemental Structural
Inspection Documents (SSID) which describe inspection programs to
detect fatigue cracking, and
Assess damage-tolerance of structural repairs.
By Federal Register notice, dated November 30, 1992 (57 FR 56627),
the
[[Page 24109]]
AATF was placed under the auspices of the Aviation Rulemaking Advisory
Committee (ARAC) and renamed as the Airworthiness Assurance Working
Group (AAWG). Structures Task Groups, sponsored by the AAWG, were
assigned the task of developing the five elements into workable
programs. The AAWG completed work on the first four of the elements
lists above at the time Notice 97-16 was issued. Issuance of this final
rule completes the fifth element.
This final rule addresses the specific task assigned to the AAWG
relevant to the fifth element, which was to develop recommendations
concerning whether new or revised requirements and compliance methods
for structural repair assessments of existing repairs should be
initiated and mandated for the following airplanes.
Airbus Model A300 (excluding the -600 series);
British Aerospace Model BAC 1-11;
Boeing Models 707/720, 727, 737, and 747;
McDonnell Douglas Models DC-8, DC-9/MD-80, and DC-10;
Fokker Model F-28;and
Lockheed Model L-1011.
Related Regulatory Activity
In addition to these initiatives, there are other on-going
activities associated with FAA's Aging Aircraft Program.
The Aging Aircraft Safety Act of 1991 (Public Law 49 U.S.C. 44717)
instructed the FAA Administrator to prescribe regulations that will
ensure the continuing airworthiness of aging aircraft through
inspections and reviews of the maintenance record of each aircraft an
air carrier uses in air transportation. In response, the FAA published
Notice 93-14 (58 FR 51944, October 5, 1993)). Among other things, that
notice proposed to require operators to.
Certify aging airplane maintenance actions;
Establish a framework for imposing operational limits
on certain airplanes; and
Perform additional maintenance actions, such as
inspections or parts replacements, in order to continue operating
the airplane.
The FAA subsequently withdraw Notice 94-14, and issued a new Notice
99-02 (64 FR 16298, April 2, 1999). The new notice proposes to require
that all airplanes operating under parts 121, 129, and 135 undergo
records reviews and inspection after their 14th year in service to
ensure that the maintenance of these airplanes' age-sensitive parts and
components has been adequate and timely. The proposed new rule also
would prohibit operation of these airplanes after specified deadlines,
unless damage-tolerance-based inspections and procedures are included
in their maintenance or inspection program. The period or public
comment on the proposal ended on August 2, 1999, and the FAA
anticipates regulatory action in the near future.
In addition, the FAA has found that some operators do not have a
programmatic approach to corrosion prevention and control programs
(CPCP). In its accident investigation report (NTSB/AAR-89/03) on the
Hawaii accident, the NTSB recommended that the FAA mandate a
comprehensive and systematic CPCP. Therefore, the FAA is considering
rulemaking to mandate CPCP's for all airplanes used in air
transportation. As part of that deliberation, the FAA is considering
the CPCP's recommended by the AATF and previously mandated by the FAA
through airworthiness directives (AD); all of the airplanes affected by
this proposal currently are subject to those AD's.
The Concern Posed by Older Repairs
The basic structure of the large jet transports that are affected
by this final rule was required at the time of original certification
to meet the applicable regulatory standards for fatigue or fail-safe
strength. Repairs and modifications to this structure also were
required to meet these same standards. The early fatigue or fail-safe
requirements, however, did not provide for timely inspection of
critical structure so that damaged or failed components could be
dependably identified and repaired or replaced before a hazardous
condition developed.
By amendment 25-45 (43 FR 46242, October 5, 1978), the FAA amended
Sec. 25.571 (``Damage-tolerance and fatigue evaluation of structure'')
by introducing a new certification requirement called ``damaged-
tolerance'' to assure the continued structural integrity of transport
category airplanes certificated after that time. Additionally, for
existing designs, guidance material based on that amendment was
published in 1981 as Advisory Circular (AC 91-56), ``Supplemental
Structural Inspection Program for Large Transport Category Airplanes.''
Damage-tolerance is a structural design and inspection methodology
used to maintain safety, considering the possibility of metal fatigue
or other structural damage (i.e., safety is maintained by adequate
structural inspection until the damage is repaired). The underlying
principle for damage-tolerance is that the initiation and growth of
structural fatigue damage can be anticipated with sufficient precision
to allow inspection programs to safely detect damage before it reaches
a critical size. A damage-tolerance evaluation entails.
The prediction of sites where fatigue cracks are most
likely to initiate in the airplane structure;
The prediction of the crack growth under repeated
airplane structural loading;
The prediction of the size of the damage at which
strength limits are exceeded; and
An analysis of the potential opportunities for
inspection of the damage as it progress.
Information from the evaluation is used to establish an inspection
program for structure, which, if rigorously followed, will be able to
detect cracking that may develop before it precipitates a major
structural failure. The evidence to date is that, when all critical
structure is included, the damage-tolerance concept and the
supplemental inspection programs that are based on it provide the best
assurance of continued structural integrity that currently is
available.
In order to apply the damage tolerance concept to existing
transport airplanes, the FAA issued a series of AD's, beginning in
1984, that require operators to comply with supplemental structure
inspection programs resulting from the concept's application to
existing airplanes. Nearly all of the airplane models affected by this
final rule currently are subject to such AD's. Generally, those AD's
require that operators incorporate Supplemental Structural Inspection
Documents (SSID) into their maintenance programs for the affected
airplanes. These documents were derived from damage-tolerance
assessments of the originally-certificate type designs for these
airplanes. For this reason, the majority of AD's written for the SSID
program did not attempt to address issues relating to the damage-
tolerance of repairs that had been made to the airplanes. The objective
of this final rule is to provide that same level of assurance for areas
of the structure that have been repaired.
Repairs are a concern on older airplanes because of the possibility
that they may develop, cause, or obscure metal fatigue, corrosion, or
other damage during service. This damage might occur within the repair
itself or in the adjacent structure, and might ultimately lead to
structural failure. The damage-tolerance evaluation of a repair would
be used in an assessment program to establish an appropriate inspection
program, or a replacement schedule if the necessary inspection program
is too demanding or not possible. The objective of the repair
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assessment is to assure the continued structural integrity of the
repaired and adjacent structure based on damage-tolerance principles.
In general, repairs present a more challenging problem to solve
than the original structure because each repair is unique and tailored
in design to correct particular damage to the original structure.
Whereas the performance of the original structure may be predicted from
tests and from experience on other airplanes in service, the behavior
of a repair and its effect on the fatigue characteristics of the
original structure are generally not known to the same extent as for
the basic unrepaired structure.
The available service record and surveys of out-of-service and in-
service airplanes have indicated that existing repairs generally
perform well. Although the cause of an airplane accident has never been
attributed to properly applied repairs using the original repair data,
repairs may be of concern as time-in-service increases for the
following reasons:
1. As airplane age, both the number and age of the existing repairs
increase. Along with this increase is the possibility of unforeseen
repair interaction, autogenous failure, or other damage occurring in
the repaired area. The continued operational safety of these airplanes
depends primarily on a satisfactory maintenance program (inspections
conducted at the right time, in the right place, using the most
appropriate technique). To develop this program, a damage-tolerance
evaluation of repairs to flight critical structure is essential. The
longer an airplane is in service, the more important this evaluation
and a subsequent inspection program become.
2. The practice of damage-tolerance methodology has evolved
gradually over the last 20 or more years. Some repair described in the
airplane manufacturers' Structural Repair Manuals (SRM) were not
designed to current standards. Repairs accomplished in accordance with
the information contained in the early versions of the SRM's may
require additional inspections if evaluated using the current
methodology.
3. Because a regulatory requirement for damage-tolerance was not
applied to airplane designs type certificated before 1978, the damage-
tolerance characteristics of repairs may vary widely and are largely
unknown.
Development of ``Repair Assessment Guidelines''
To address the ARAC assignment relative to repairs, the AAWG tasked
the manufacturers to develop ``repair assessment guidelines (RAG)''
requiring specific maintenance programs to maintain the damage-
tolerance integrity of the basic airframe. The following criteria were
developed to assist the manufacturers in the development of the
guidance material:
Repairs that do not conform to SRM standards must be
reviewed and may require further action.
Repairs must be reviewed where the repair has been
installed in accordance with SRM data that have been superseded or
rendered inactive by new damage-tolerant designs.
Repairs that are in close proximity to other repairs or
modifications require review to determine their impact on the
continued airworthiness of the airplane.
Repairs that exhibit structural distress should be
replaced before flight.
To identify the scope of the overall program, fleet data were
required. This resulted in the development of a five-step program to
develop factual data for the development of the rule. The five-step
AAWG program consisted of:
Step 1. Development of model specific RAG's using AAWG repair
criteria.
Step 2. Completion of a survey of a number of operators' airplanes
to assess fuselage skin repairs and to validate the approach of the
manufacturer's RAG.
Step 3. Determination of the need for and the development of a
worldwide survey.
Step 4. Collection and assessment of results to determine further
necessary actions.
Step 5. Development of specific manufacturer/operator/FAA actions.
Early in the development of this task, each manufacturer began to
prepare model-specific RAG's. When sufficiently developed, these draft
guidelines were shared with the operators to get feedback on
acceptability and suggestions for improvement. The operators stressed
the need for commonality in approach and ease of use of the guidelines.
They also expressed the need for guidelines that could be used on the
shop floor without engineering assistance and without extensive
training.
Meanwhile, the AAWG conducted two separate surveys of existing
repairs on airplanes to collect necessary data. The first survey was
conducted in March 1992 on certain large transport category airplanes
being held in storage. Teams comprised of engineering representatives
from various organizations, including FAA's Aircraft Certification and
Flight Standards offices, operators, and manufacturers, surveyed 356
external fuselage skin repairs on 30 airplanes of 6 types. Using repair
classification criteria developed by the individual airplane
manufacturers, the teams concluded that the general quality of the
repairs appeared good. Forty percent of the repairs were adequate,
requiring no supplemental inspections, and sixty percent needed a more
comprehensive damage-tolerance based assessment, with the possibility
that supplemental inspections might be needed. Some determining factors
on the need for further assessment were the size of the repair and its
proximity to other repairs. While the survey sample size was very small
compared to the total population of transport airplanes type
certificated prior to 1978, it provided objective information on the
quality and damage-tolerance characteristics of existing airplane
repairs.
In 1994, the AAWG requested that the manufacturers conduct a second
survey on airplane repairs to validate the 1992 results and to provide
additional information relative to the estimated cost of the assessment
program. The manufacturers were requested to visit airplanes that were
operating their products and to conduct surveys on airplanes that were
currently undergoing heavy maintenance. An additional 35 airplanes were
surveyed in which 695 repairs were evaluated. This survey was expanded
to include all areas of the airframe. The evaluation revealed
substantially similar results to the 1992 results: forty percent of the
repairs were classified as adequate, and sixty percent of the repairs
required consideration for additional supplemental inspection during
service. In addition, only a small number of repairs (less than 10
percent) were found on portions of the airframe other than the external
fuselage skin.
The AAWG proposed that the repair assessment be initially limited
to the fuselage pressure boundary; if necessary, future rulemaking
would address the remaining primary structure. This limitation was
based on two considerations:
First, the fuselage is more sensitive to structural fatigue than
other airplane structure because its normal operating loads are closer
to its limit design loads. Stresses in a fuselage are primarily
governed by the pressure relief valve settings of the environmental
control system, and these are less variable from flight to flight than
the gust or maneuver loads that typically determine the design stresses
in other structure.
Second, the fuselage is more prone to damage from ground service
equipment than other structure and requires repair more often. The
result of the second survey described above supports the
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conclusion that repairs to the fuselage are far more frequent than to
any other structure.
Determining Which Airplanes Should Be Affected
This final rule and the repair assessment guidelines apply to 11
large transport category airplane models. (In the original ARAC task,
the Boeing Models 707 and 720 were counted as one model. This final
rule addresses the 707 and 720 models separately due to their different
flight cycle implementation times.) The reason for this limitation is
that the original tasking to the ARAC limited the scope of the work to
the 11 oldest models of large transport category airplanes then in
regular service. This tasking identified those airplanes for which the
great concern exists as to the status of primary structure repairs.
Derivatives of the original airplane models are covered to the extent
that the structure has not been upgraded to meet damage-tolerance
requirements.
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 repair 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 the newer airplanes, with
the possibility of additional rulemaking if conditions warrant. (A copy
of the AAWG's final report is included in the public docket for this
rulemaking).
It was from this activity that the AAWG and 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.
Considerations in Developing and Mandating Repair Assessment
Guidelines
In considering the establishment of RAG's, the AAWG recognized that
the guidelines would add to existing repair approval data and, in some
cases, may even appear to be in conflict with that data. All repairs
assessed under the requirements of this final rule should have been
previously approved by the FAA using an FAA using an FAA-approved SRM,
an FAA-approved Service Bulletin, or a repair scheme approved by either
an FAA Designated Engineering Representative or an SFAR 36
authorization holder. To avoid the appearance of conflicts between FAA
approved data sources, the manufacturers have agreed to update the
affected SRM's, as well as repairs identified in Service Bulletins, to
determine requirements for supplemental inspections, if not already
addressed.
Another consideration was that structural modifications and repairs
mandated by AD's do not always contain instructions for future
supplemental inspection requirements. The manufacturers have agreed to
evaluate the need for post modification inspections for these mandated
modifications and repairs. A list of Service Bulletins that are the
subject of AD's will be contained in the model-specific RAG documents,
with required post-modification/repair inspection programs, as
appropriate. A list of other structural Service Bulletins will be
provided in the model-specific RAG document, with associated inspection
thresholds and repeat intervals. The manufacturers have agreed to
complete their review of Service Bulletins related to skin repairs in
conjunction with the initial SRM updates.
These agreements notwithstanding, there is still a possibility that
the requirements in the RAG document will not agree with those in an
AD, especially if the AD was written to address a modification to the
airplane made by someone other than the original manufacturer. Federal
Aviation Regulations require that compliance be shown with both the AD
and this final rule. Such dual compliance can be avoided in the longer
term by working with the manufacturer, if that is the source of
difficulty, or by securing an Alternative Method of Compliance (AMOC)
to the AD. In the short term, compliance with the earlier threshold,
shorter repeat inspection interval or more stringent rework/replace
schedule would always constitute compliance with the less stringent
requirement. Thus, the operator would not be faced with an unresolvable
conflict.
Another consideration, and one that the AATF originally
recommended, was that the use of RAG's be mandated by an AD. The FAA
concluded that an unsafe condition necessitating AD action had not been
established for repairs, and this position is supported by both repair
surveys. However, the FAA also considered, and the AAWG agreed, that
the long term concern with repairs on older airplanes, as described
earlier, does warrant regulatory action, and this final rule addresses
that concern.
The AAWG also recognized that the concerns discussed above for the
safety of existing repairs also would apply to the long-term safety of
future repairs to these airplanes. Therefore, the AAWG considered that
new repairs also should be subject to damage-tolerance assessments. It
is expected that most new repairs will be installed in accordance with
an FAA-approved SRM that has been updated to include this damage-
tolerance assessment. However, in the event that a new repair is
installed for which no such assessment has been made or is available,
the repair assessment guidelines prepared to meet the requirements of
this final rule should be used. The intent of this final rule is that
all repairs to the fuselage pressure boundary will be evaluated for
damage-tolerance, and that any resulting inspection schedule will be
specified and the work accomplished, regardless of when, where, or by
whom the repair was installed.
Development of Repair Assessment Methodology
The next step in the AAGW's program for this task was to develop a
repair assessment methodology that is effective in evaluating the
continued airworthiness of existing repairs for the fuselage pressure
boundary on affected transport category airplane models. Older airplane
models may have many structural repairs, so the efficiency of the
assessment procedure is an important consideration. In the past,
evaluation of repairs for damage-tolerance would require direct
assistance from the manufacturer. The size of an assessment task
conducted in that way would be unmanageable considering that:
Each repair design is different,
Each airplane model is different,
Each area of the airplane is subjected to a different
loading environemnt, and
The number of engineers qualified to perform a damage-
tolerance assessment is small.
Therefore, a new approach was developed.
Since repair assessment results will depend on the model-specific
structure and loading environment, the manufacturers were tasked to
create an assessment methodology for the types of repairs expected to
be found on each affected airplane model. Since the records on most of
these repairs are not readily available, locating the repairs
necessitates surveying the structure of each airplane. A survey form
was created that may be used to record key repair design features
needed to accomplish a repair assessment. Airline
[[Page 24112]]
personnel not trained as damage-tolerance specialists can use the form
to document the configuration of each observed repair.
Using the information gathered during the survey as input data, the
manufacturers have developed simplified methods to determine the
damage-tolerance characteristics of the surveyed repairs. Although the
repair assessments should be performed by well-trained personnel
familiar with the model specific repair assessment guidelines, these
methods enable an engineer or technician, not trained as a damage-
tolerance specialist, to perform the repair assessment without the
assistance of the manufacturer.
From the information gathered during the survey, it is also
possible to classify repairs into one of three categories:
Category A: A permanent repair for which the baseline zonal
inspection (BZI), (typical maintenance inspection intervals assumed to
be performed by most operators), is adequate to ensure continued
airworthiness (inspectability) equal to the unrepaired surrounding
structure.
Category B: A permanent repair that requires supplemental
inspections to ensure continued airworthiness.
Category C: A temporary repair that will need to be reworked or
replaced prior to an established time limit. Supplemental inspections
may be necessary to ensure continued airworthiness prior to this limit.
The airplane manufacturers generated this methodology and are
preparing model-specific repair assessment guidelines for the 11 aging
airplane models affected by this final rule. The manufacturers chose to
produce the model-specific repair assessment guidelines for the older
models first, and to produce those for the newer models as those
airplanes get closer in age to the implementation time. (Operators
should be in contact with the manufacturers to obtain a schedule of
when the repair assessment guidelines will be prepared for their
specific airplane models.) Uniformity and similarity of these repair
assessment procedures between models has been an important factor to
consider in simplifying operator workload. The manufacturers have spent
considerable time over the last several years to achieve commonality of
the repair assessment process.
The inspection intervals contained in the FAA-approved model
specific RAG documents are based on residual strength, crack growth,
and inspectability evaluations. The manufacturers have endeavored to
make the inspection methods and intervals compatible with typical
operator maintenance practice. Thus, internal inspections would be
acceptable at flight cycle limits that are equivalent to D-check
intervals, while simpler external inspections could be accommodated at
flight cycle limits that are generally equivalent to C-check intervals.
If the inspection method and intervals for a given repair are not
compatible with the operator's maintenance schedule, the repair could
be replaced with a more damage-tolerant repair.
These guidelines can also be used for evaluating the damage-
tolerance characteristics of new repair for continued airworthiness.
Related Activity Affecting Structural Repair Manuals
In order to further facilitate the assessment process, the
manufacturers have agreed to update model-specific SRM's to reflect
damage-tolerance repair considerations. Their goal is to complete these
updates by the first revision cycle of the model-specific SRM after the
release of the associated RAG document. Consistent with the results of
the surveys, only fuselage pressure boundary repairs are under
consideration.
The general section of each SRM, Chapter 51, will contain brief
descriptions of damage-tolerance considerations, categories of repairs,
description of baseline zonal inspections, and the repair assessment
logic diagram. Chapter 53 of the SRM for pressurized fuselage skin will
be updated to identify repair categories and related information.
In updating each SRM, existing location-specific repairs should be
labeled with appropriate repair category identification (A, B, or C),
and specific inspection requirements for B and C repairs also should be
provided, as applicable.
Structural Repair Manual descriptions of generic repairs also will
contain repair category considerations regarding size, zone, and
proximity. Detailed information for determination of inspection
requirements will be provided in separate RAG documents for each model.
Repairs that were installed in accordance with a once-current SRM, but
that have now been superseded by a new damage-tolerant design, will
require review. Such superseded repairs may be reclassified to Category
A, B, or C. Category B or C repairs would require additional
inspections and/or rework.
Repair Assessment Process
There are two principal techniques that can be used to accomplish
the repair assessment. The first technique involves a three-stage
procedure. This technique could be well-suited for operators of small
fleets. The second technique involves the incorporation of the RAG as
part of an operator's routine maintenance program. This approach could
be well-suited for operators of large fleets and would evaluate repairs
at predetermined planned maintenance visits as part of the maintenance
program.
Manufacturers and operators also may develop other techniques,
which would be acceptable as long as they fulfill the objectives of
this rule and are FAA approved.
The first technique generally involves the execution of the
following three stages:
Stage 1. Data Collection. This stage specifies what
structure should be assessed for repairs and collects data for further
analysis. If a repair is on a structure in an area of concern, the
analysis continues; otherwise, the repair does not require
classification per this program. Repair assessment guidelines for each
model will provide a list of structure for which repair assessments are
required. Some manufacturers have reduced this list by determining the
inspection requirements for critical details. If the requirements are
equal to normal maintenance checks (e.g., BZI checks), those details
were excluded from this list. Repair details are collected for further
analysis in State 2. Repairs that do not meet the static strength
requirements or are in a bad condition are immediately identified, and
corrective actions must be taken before further flight.
Stage 2. Repair Categorization. The repair categorization
is accomplished by using the data gathered in Stage 1 to answer simple
questions regarding structural characteristics. If the maintenance
program is at least as rigorous as the BZI identified in the
manufacturer's model specific RAG, well-designed repairs in good
condition meeting size and proximity requirements are designed as
Category A. Simple condition and design criteria questions are provided
in Stage 2 to define the lower bounds of Category B and Category C
repairs. The process continues for Category B and C repairs.
Stage 3. Determination of Structural Maintenance
Requirements. The supplemental inspection and/or replacement
requirements for Category B and C repairs are determined in this stage.
Inspection requirements for the
[[Page 24113]]
repair are determined by calculation or by using predetermined values
provided by the manufacturer, or other values obtained using an FAA-
approved method. In evaluating the first supplemental inspection, Stage
3 defines the inspection threshold in flight cycles measured from the
time of repair installation. If the time of installation of the repair
is unknown and the airplane has exceeded the assessment implementation
times or has exceeded the time for first inspection, the first
inspection should occur by the next C-check interval, or equivalent
cycle limit after the repair data is gathered (Stage 1).
An operator may choose to accomplish all three stages at once, or
just Stage 1. In the latter case, the operator would be required to
adhere to the schedule specified in the FAA-approved model-specific RAG
for completion of Stages 2 and 3.
Incorporating the maintenance requirements for Category B and C
repairs into an operator's individual airplane maintenance or
inspection program completes the repair assessment process for the
first Technique.
The second technique involves setting up a repair maintenance
program to evaluate all fuselage pressure boundary repairs at each
predetermined maintenance visit to confirm that they are permanent.
This technique requires the operator to choose an inspection method and
interval in accordance with the FAA-approved RAG. The repairs whose
inspection requirements are fulfilled by the chosen inspection method
and interval would be inspected in accordance with the regular FAA-
approved maintenance program. Any repair that is not permanent, or
whose inspection requirements are not fulfilled by the chosen
inspection method and interval, would either be: (1) Upgraded to allow
utilization of the chosen inspection method and interval, or (2)
individually tracked to account for the repair's unique inspection
method and interval requirements. This process is then repeated at the
chosen inspection interval.
Repairs added between the predetermined maintenance visits,
including interim repairs installed at remote locations, would be
required either to have a threshold greater than the length of the
predetermined maintenance visit or to be tracked individually to
account for the repair's unique inspection method and interval
requirements. This would ensure the airworthiness of the structure
until the next predetermined maintenance visit, at which time the
repair would be evaluated as part of the repair maintenance program.
Whichever technique is used, there may be some repairs that cannot
easily be upgraded to Category A due to cost, downtime, or technical
reasons. Such repairs will require supplemental inspections, and each
operator should make provisions for this when incorporating the RAG
into its maintenance program.
Repair Assessment Implementation Time
The implementation time for the assessment of existing repairs is
based on the findings of the repair surveys and fatigue damage
considerations, described previously. As discussed, the repair survey
findings indicated that all of repairs reviewed appeared to be in
generally good structural condition. This tended to validate the
manufacturer's assumptions in designing both the repair and the basic
structure. Since the manufacturer had based the design stress levels on
a chosen Design Service Goal (DSG), it was concluded that the repair
assessment needed to be implemented sometime before a specific model
reached its DSG. Based on this logic, the manufacturers and operators
established an upper boundary for an assessment to be completed, and
then reduced it to establish an ``implementation time,'' defined as 75%
of DSG in terms of flight cycles.
Therefore, under this approach, incorporation of the RAG into an
airplane's maintenance or inspection program ideally should be
accomplished before an airplane accumulates 75% of its DSG. After the
guidelines are incorporated into the maintenance or inspection program,
operators should begin the assessment process for existing fuselage
repairs within the flight cycle limit specified in the FAA-approved
model-specific RAG. There are three ``deadlines'' for beginning the
repair assessment process, depending on the cycle age of the airplane
on the effective date of the rule.
1. Airplane cycle age equal to or less than implementation time on
the rule effective date: The operator is required to incorporate the
guidelines into its maintenance or inspection program by the flight
cycle implementation time, or one year after the effective date of the
rule, whichever occurs later. The assessment process begins (e.g.,
accomplishment of Stage 1) on or before the flight cycle limit
specified in the RAG after incorporation of the guidelines. (The flight
cycle limits are expressed in flight cycle numbers, but are generally,
equivalent to a D-check.)
2. Airplane cycle age greater than the implementation time but less
than the DSG on the rule effective date: The operator is required to
incorporate the guidelines into its maintenance or inspection program
within one year of the rule effective date. The assessment process then
begins (e.g., accomplishment of Stage 1) on or before the flight cycle
limit specified in the RAG (this flight cycle limit is generally
equivalent to a D-check), not to exceed another specified flight cycle
limit (computed by adding the DSG to the flight cycle limit equivalent
of a C-check) after incorporation of the guidelines.
3. Airplane cycle age greater than the DSG on the rule effective
date: The operator is required to incorporate the guidelines in its
maintenance or inspection program within one year after the effective
date of the rule. The assessment process would begin (e.g.
accomplishment of Stage 1) on or before the flight cycle limit
specified in the RAG (generally equivalent to a C-check) after
incorporation of the guidelines.
In each of these three cases, the assessment process will have to
be completed, the inspections conducted, and any necessary corrective
action taken, all in accordance with the schedule specified in the FAA-
approved RAG document.
Discussion of the Final Rule
This final rule is intended to ensure that a comprehensive
assessment for damage-tolerance be completed for fuselage pressure
boundary repairs, and that the resulting inspections, modifications,
and corrective actions (if any) be accomplished in accordance with the
model-specific RAG. To comply with this, the operator will need to
consider the following:
Consideration 1
The means by which the FAA-approved RAG's are incorporated into a
certificate holder's FAA-approved maintenance or inspection program is
subject to approval by the certificate holder's Principal Maintenance
Inspector (PMI) or other cognizant airworthiness inspector.
Consideration 2
The FAA Aircraft Certification Office (ACO) having cognizance over
the type certificate of the airplane must approve the RAG.
Consideration 3
This final rule will not impose any new reporting requirements;
however, normal reporting required under 14 CFR 121.703 will still
apply.
[[Page 24114]]
Consideration 4
This final rule will not impose any new FAA recordkeeping
requirements. However, as with all maintenance, the current operating
regulations (e.g., 14 CFR 121.380) already impose recordkeeping
requirements that will apply to the actions required by this final
rule. When incorporating the RAG into its approved maintenance program,
each operator should address the means by which it will comply with
these recordkeeping requirements. That means of compliance, along with
the remainder of the program, will be subject to approval by the PMI or
other cognizant airworthiness inspector.
Consideration 5
The scope of the assessment is limited to repairs on the fuselage
pressure boundary (which includes fuselage skin, door skin, and
pressure webs). A list of Service Bulletins that are the subject of
AD's will be contained in the model-specific RAG with required post
modification/repair inspection programs, as required. A list of other
structural Service Bulletins will be provided in the model-specific RAG
with associated inspection threshold and repeat intervals.
Consideration 6
The RAG's provided by the manufacturer do not generally apply to
structure modified by a Supplemental Type Certificate (STC). However,
the operator will still be responsible to provide RAG's applicable to
the entire fuselage external pressure boundary that meets the program
objectives specified in the advisory circular (AC) associated with this
final rule (which will be available in the near future). This means
that the operator should develop, submit, and gain FAA approval of
guidelines to evaluate repairs to such structure.
The FAA recognizes that operators usually do not have the resources
to determine a DSG or to develop RAG's, even for a very simple piece of
structure. The FAA expects the STC holder to assist the operators in
preparing the required documents. If the STC holder is out of business,
or is otherwise unable to provide assistance, the operator will have to
acquire the FAA-approved guidelines independently. To keep the
airplanes in service, it is always possible for operators, individually
or as a group, to hire the necessary expertise to develop and gain
approval of RAG's and the associated DSG. Ultimately, the operator
remains responsible for the continued safe operation of the airplane.
The cost and difficulty of developing guidelines for modified
structure may be less than that for the basic airplane structure for
three reasons:
First, the only modifications made by persons other than the
manufacturer that are of concern in complying with this final rule are
those that affect the fuselage pressure boundary. Of those that do
affect this structure, many are small enough to qualify as Category A
repairs under the RAG, based solely on their size.
Second, if the modified structure is identical or very similar to
the manufacturer's original structure, then only a cursory
investigation may be necessary. In such cases, the manufacturer's RAG
may be shown to be applicable with few, if any, changes. If the
operator determines that a repair to modified structure can be
evaluated using the manufacturer's model-specific RAG, that determined
should be documented and submitted to the operator's PMI or other
cognizant airworthiness inspector for approval. For all other repairs,
a separate program will need to be developed.
Third, the modification may have been made so recently that no RAG
will be needed for many years. Compliance with this final rule could be
shown by:
Establishing the DSG for the new modified structure,
Calculating an implementation time that is equal to
three quarters of that DSG, and
Then adding a statement to the operations
specifications for part 121, 125 and 129 operators that the RAG will
be incorporated into the maintenance or inspection program by that
time. For part 91 operators, the inspection program will be revised
to include the RAG.
If the modified structure is very similar to the original, then the
DSG for the modified structure may also be very similar. No RAG would
be needed until 75% of that goal is reached. For example, in the case
of a large cargo door, such installations are often made after the
airplane has reached the end of its useful life as a passenger-carrying
airplane. For new structure, the clock would start on repair assessment
at the time of installation. Further, since the DSG is measured in
cycles, and cargo operation usually entails fewer operational cycles
than passenger operations, the due date for incorporation of the RAG
for that structure could be many years away.
Compliance with this final rule requires that conditions such as
those described above be properly documented in each operator's FAA-
approved maintenance program; however, the FAA considers that the cost
of doing so should not be significant. There should be very few
examples where the STC holder is unavailable, and the operators would
have to bear the cost of developing a complete RAG document. Guidance
on how to comply with this aspect of the rule is discussed in the soon-
to-be-released AC associated with this rule.
Consideration 7
An operator's repair assessment program will have to include
damage-tolerance assessments for new repairs. Repairs made in
accordance with the revised version of the SRM would already have a
damage-tolerance assessment performed; otherwise, the manufacturer's
RAG could be used for this purpose, or operators may develop other
methods as long as they achieve the same objectives.
Consideration 8
Once the airworthiness inspector having oversight responsibilities
is satisfied that the operator's continued airworthiness maintenance or
inspection program contains all of the elements of the FAA-approved
RAG, the airworthiness inspector will approve a maintenance program or
inspection program revision. This will have the effect of requiring use
of the approved RAG.
In summary, based on discussions with representatives of the
affected industry, recommendations from ARAC, and a review of current
rules and regulations affecting repair of primary structure, the FAA
recognizes the need for a repairs assessment program to be incorporated
into the maintenance program for certain transport category airplanes.
This final rule accomplishes that.
Discussion of Comments
The FAA received 16 comments in response to Notice 97-16. Comments
included airplane manufacturers, airplane operators, non-U.S. aviation
authorities, and aviation industry representatives and groups. The
disposition of all comments, grouped by subject, follows.
Support for the Proposal
Several commenters support the proposed rule.
No Need for the Rule
One commenter contends that the proposed rule is largely redundant
and may not even be needed. The commenter points out that, in 1978,
with amendment 25-45, the FAA amendment Sec. 25.571 to impose damage-
tolerance criteria for design of aircraft structure. Airplanes
certified after that
[[Page 24115]]
date have damage-tolerance criteria built in to the manufacturers'
repair philosophies. Airplanes older than that are regulated by FAA-
approved Supplemental Inspection Documents.
The commenter also points out that, in 1989 (ref. memorandum from
Manager, Transport Airplane Directorate, ``Policy Regarding Impact of
Modification and Repairs on the Damage-tolerance Characteristics of
Transport Category Airplanes,'' dated November 27, 1989), the FAA
clarified that ``* * * All transport category airplanes having the
damage-tolerance requirements of Sec. 25.571, amendment 25-45, as their
certification basis and those with mandated Supplemental Inspection
Documents [SID] * * * must continue to maintain their damage-tolerance
characteristics when repaired or modified in any way.'' Industry has
adhered to this rendering since that time.
Thus, through the certification rule for new airplanes and through
the SID programs for older airplanes, the damage-tolerance assessment
of repairs is already being done. For this reason, commenter does not
see a need for the proposed rule and implies that it should be
withdrawn.
The FAA acknowledges the commenters' observations, but does not
occur that the rule is unnecessary. As discussed in the preamble to the
notice (and this final rule), the airplanes certified after amendment
25-45 must be maintained in accordance with their certification basis
and, therefore, a damage-tolerance analysis of all repairs is required.
The 1989 memorandum was issued by the FAA to clarify that operators
with airplanes subject to the mandated SID programs should continue to
maintain the damage-tolerance capabilities of the airplanes when
repaired or modified in any way. However, all operators of the
airplanes covered by SSID's have not routinely followed this policy.
This fact was made clear by the adoption of Airworthiness Directive
(AD) 98-11-03 (Amdt. 39-10530; 63 FR 27455, May 19, 1998) and AD 98-11-
04 (Amdt. 39-10531; 63 FR 27456, May 19, 1988) which revised the SSID
programs for the Model 727 and 737, respectively. In response to the
NPRM's for those AD's, numerous commenters (including the ATA) objected
to proposed requirements that repairs be assessed. In part, these
objections were based on the argument that operators did not have the
records to identify, or the methods to assess existing repairs. The
FAA, as well as the AAWG, in developing the repair assessment program,
concluded that it is necessary to assess the repairs on all of the
affected 11 models of (aging) aircraft to ensure that the original
intent of the SID programs (and related AD's mandating them) is being
followed.
Manufacturers' Commitments to Providing Documents
Two commenters suggest that adoption of the rule and implementation
of the repair assessment program be delayed until the RAG documents,
revised SRM's, and service bulletins are available from the
manufacturers to affected operators.
One of these commenters states that the FAA should not rely on
verbal commitments from the manufacturers to issue these documents
sometime in the future. The commenter further states that commitments
cannot be depended on, especially where manufacturers are operating
with greatly reduced staffs and resources (i.e., due to takeovers). The
commenter suggests that, if manufacturers are unable to supply these
documents in a timely manner, operators may find themselves in
situations where they are not in compliance with this rule.
The other commenter points out that the manufacturer has not
provided any information regarding the SRM update schedule for the
affected airplanes in this commenter's fleet. The commenter states
that, being unable to review the SRM beforehand, raises concerns about
possible conflicts between the model-specific RAG document and the
corresponding SRM. If the FAA does not delay implementation of the
rule, this commenter requests that an appropriate ``grace period'' be
provided after the SRM's are completely updated so that operators will
have time to incorporate the new changes.
The FAA acknowledges these commenters' concerns, but does not agree
that a delay is necessary. This final rule is written such that it
neither requires the type certificate (TC) holder to develop the
guidelines, nor depends on this issuance of any documents from the TC
holder to be enforceable. As stated in the preamble to the notice and
this final rule, the operator is responsible for providing the RAG
applicable to the fuselage external pressure boundary of the airplanes
in its fleet. If the TC holder does not or cannot provide relevant
service information, the operator may develop, submit, and gain
approval of its own guidelines to evaluate repairs to such
structure.The information contained in the soon-to-be-released
accompanying AC describes one method that may be used by any entity--
operator, TC holder, or otherwise--to develop such guidelines.
Additionally, it is always possible for operators, individually or as a
group, to hire the necessary expertise to develop and gain approval of
RAG's. Ultimately, however, the operator remains responsible for the
continued safe operation of its airplanes.
Further, the FAA also does not concur with the commenter's request
that implementation of the repair assessment program be postponed, or a
grace period provided, until SRM's are updated to correspond with the
RAG documents. The purpose of the two documents is different: the
purpose of the RAG document is to assist in evaluating existing
repairs; the purpose of the updated SRM is, as is usual, to assist in
the installation of new repairs. Operators affected by this new rule
will be required to show how new repairs installed after the effective
date of the final rule will be handled. The methods described in the
soon-to-be-released AC associated with this rule also may be used for
this purpose.
The FAA has been advised, however, that as of the date of
publication of this rule, the manufacturers have finalized the RAG's
applicable to the older airplane models affected by this rule. The
guidelines for the newer models are nearly complete and certainly will
be finalized by the time the newer models will require the initial
inspections.
Further, the FAA also has been advised that the manufacturers (1)
have completed updating the pertinent parts of their Structural Repair
Manuals and (2) are ready to provide necessary training programs.
Airplanes Subject to the Final Rule
Airbus Models Subject to Rule. One commenter requests that the
listing of affected models of Airbus airplanes in the proposed rule be
revised as follows:
Change references to the Airbus A300 to: ``Airbus A300
(excluding the -600 series); and
Clarify paragraph (a)(3) of the proposed Sec. 91.410,
Sec. 121.370, Sec. 125.248; and Sec. 129.32 to include references to
the Airbus Model C4-200 and F4-200 models.
The FAA concurs with the commenter's first request to exclude the
Airbus A300-600 series from the applicability of the rule, and has
revised the text of the final rule accordingly. The FAA finds it is
appropriate to exclude the Airbus A300-600 series from the
applicability of this rule because this model been certified to
regulatory standards that include the requirements for damage-tolerant
structure under Sec. 25.571, as amended by amendment 25-45. As
explained earlier, such airplanes are not included in this rulemaking
action. An Airworthiness Limitations Section has been approved
[[Page 24116]]
for the Airbus A300-600 series airplanes, and it is considered a
damage-tolerant airplane. Based on the Airbus airplanes currently
certificated in the U.S., the following airplanes in the Model A300-600
series would be excluded from compliance with this rule:
A300 Model B4-600 series,
A300 Model B4-600R series, and
A300 Model F4-600R series.
The FAA does not concur with the commenter's second request to add
references to Airbus A300 Model C4-200 and A300 Model F4-200 model
airplanes to the applicability of the rule. The C4-200 and F4-200 model
airplanes currently are not certified in the U.S. and, therefore,
cannot be made part of the rule's applicability.
In light of this commenter's requests, the FAA finds that
additional clarification is appropriate as to specify exactly which
Airbus A300 airplanes are subject to the requirements of this rule.
In Sec. 91.410, Sec. 121.270, Sec. 125.248, and Sec. 129.32, the
FAA delineates the Airbus A300 ``Model B2'' as a separate model, whose
implementation threshold is 36,000 flights, Based on the airplanes
currently certified in the U.S. specified in Type Certificate Data
Sheet (TCDS) A35EU, the ``A300 Model B2'' designation referred to in
the rule includes:
Model B2-1A,
Model B2-1C,
Model B2K-3C, and
Model B2-203.
If any new ``Model B2'' airplanes are certified in the U.S. in the
future, those airplanes would be required to follow he implementation
time of 36,000 flights above the window line and 36,000 flights below
the window line, as outlined in the rule.
Readers also note that, in Sec. 91.410, Sec. 121.370, Sec. 125.248,
and Sec. 129.32, the FAA delineates the Airbus A300 ``Model B4-100
(including Model B4-2C)'' as a separate model whose implementation
threshold is 30,000 flights above the window line and 36,000 flights
below the window line. Based on the airplanes currently certificated in
the U.S. specified in TCDS A35EU, this model designation referred to in
the rule includes:
Model B4-103 and
Model B4-2C.
If any new ``Model B4-100'' airplanes are certificated in the U.S.
in the future, those airplanes would be required to follow the
implementation time of 30,000 flights above the window line and 36,000
flights below the window line, as outlined in the rule.
Further, in Sec. 91.410, Sec. 121.370, Sec. 125.248, and
Sec. 129.32 and FAA, delineates the Airbus A300 ``Model B4-200.'' as a
separate model whose implementation threshold is 25,000 flights above
the window line and 34,000 flights below the window line. Based on the
airplanes currently cerfificated in the U.S. specified in TCDS A35EU,
this model designation referred to in the rule is the Model B4-203.
If any new ``Model B-200'' airplanes are certificated in the U.S.
in the future, those airplanes would be required to follow the
implementation time of 25,500 flights above the window line and 34,000
flights below the window line, as outlined in the rule.
Fokker Models Subject to Rule. One commenter states that the AAWG
recommended that only the Fokker F28 Mark 1000 through 4000 airplanes
were to be affected by this action. The commenter requests that
proposed paragraph (1) of the affected regulations be revised to
specify this. The proposal includes reference to the Mark 1000C and
3000C models, which is incorrect.
The FAA concurs. The Mark 1000C and 3000C were inadvertently added
to the applicability of the proposed rule. References to those models
have been deleted from the final rule.
Boeing Models Subject to Rule. Another commenter requests
clarification as to whether the Boeing Model 737-300 is affected by the
proposed rule. The commenter notes that the Boeing 737 Repair
Assessment Guidelines appear to address only the -100 and -200 models,
whereas the proposed rule appears to include the -300.
The FAA points out that the Boeing 737-300 is included in the
applicability of the rule, as are all models of the Boeing 737. The
manufacturers usually produce documents for the older airplanes first
before they produce documents for the newer model airplanes Boeing has
advised the FAA that it will produce RAG's for all the models of the
Boeing 737. Boeing is expected to produce the documents based on how
soon the fleet leaders for a specific model will reach the mandated
implementation time. The operators should maintain close contact with
the manufacturers to obtain a schedule of when the model-specific RAG's
will be produced.
General Applicability of the Rule. Another commenter notes that the
proposed rule did not mention the ``later design'' airplanes, that is,
airplanes that are certified to Sec. 25.571, amendment 25-45, or later.
The commenter requests clarification as to whether these airplanes
would be affected by the proposed rule.
The FAA concurs with the commenter's observation that the proposal
did not mention the term ``later design [airplanes].'' The FAA infers
that the commenter uses this term to refer to airplanes certificated
after the time that amendment 25-45 became effective. As explained
previously, damage-tolerance requirements were introduced into the
airplane design in post-amendment 25-45 airplanes, and the certificate
holder is required by the amendment to return repaired airplane
structure to the original certification basis by installing only those
repairs that meet the airplane's damage-tolerance certification basis.
In light of the fact that damage-tolerance is ``designed into'' the
post-amendment 25-45 airplanes, the FAA considers it unnecessary to
include those airplanes in this rule. This final rule, therefore,
applies to those airplanes whose certification basis was approved
before amendment 25-45 became effective, and were not designed with
requirements for damage-tolerant structure. [The FAA points out,
however, that the AAWG did recommend continued monitoring of repairs on
the newer (``later design'') airplanes, and additional rulemaking if
conditions warrant.]
Areas of Inspection
One commenter requests that the FAA clarify the proposed rule to
indicate that the area of inspection termed the ``fuselage pressure
boundary'' includes not only the fuselage skin and bulkhead web, but
the door skin as well.
The FAA concurs. The intent of the repair assessment is to include
the entire fuselage pressure boundary, which does include, among other
things, the fuselage, bulkhead webs, and the door skin. (The preamble
to the proposal, in fact, did refer to assessment of modified structure
relevant to large cargo doors.) The rule has been revised for clarity
as suggested by the commenter.
Effective Date of the Rule
One commenter requests that the effective date of the final rule be
changed to at least one year after each of the model-specific RAG
documents is officially approved and published. The commenter further
requests that an additional grace period be added to allow operators
the time for preparation work before starting a new complicated program
like the repair assessment program and time to train their personnel.
The commenter states that
[[Page 24117]]
none of the model-specific RAG's developed by manufacturers have been
officially approved yet by the FAA, and it is difficult for the
operators to review and prepare for implementing the program without
the actual guideline materials in hand. To justify this request, the
commenter points out that the FAA previously provided similar extended
compliance times for incorporating other complex programs such as the
CPCP and the SSID programs.
The FAA does not concur that a revision to the effective date of
the final rule is appropriate. As it is written, the rule does allow a
``grace period'' of one year after the effective date for operators to
implement the program. (This is similar to the provisions of the CPCP
and SSID programs.) The FAA also points out that operators and airlines
have had the opportunity to work with the manufacturers in the
development of the guidelines over the past 6 years. The FAA already
has reviewed the RAG documents for 9 of the 11 models affected by the
rule and has found that they would satisfy the intent of the rule, the
FAA will approve these RAG documents when the rule becomes effective.
However, even if these documents are not approved, the rule places the
onus on the operators to have guidelines and a program in place. The
airframe manufacturers are providing the RAG documents as a ``service''
to their customers. However, if the manufacturer does not have a RAG
document available, the operator would still be required to develop
repair assessment guidelines. Therefore, trying the compliance time of
the rule in any way with the date of publication of the manufacturers'
documents is immaterial.
Another commenter requests that the proposed implementation time be
increased from 1 year to 18 months to allow manufacturers adequate time
``to respond to the new rule.'' The commenter is concerned that the
proposed rule will be implemented sooner than the manufacturers can
support the operators with inspection thresholds and repeat inspection
intervals for multiple repair configurations, Service Bulletin repairs,
and SRM repairs.
The FAA does not concur that additional calendar time for
implementation is appropriate. The FAA has reached this conclusion for
several reasons:
First, the original notice of this rulemaking provided a 3-month
period for public comments. The FAA later reopened the comment period
for an additional 3 months to allow the manufacturers time to
distribute copies of the RAG's and allow the operators time to review
those documents and provide comments.
Second, industry has been aware of the need to assess the damage-
tolerance of repairs since at least 1978, when amendment 25-45 was
issued to impose damage-tolerance criteria for design of aircraft
structure. Airplanes certificated after 1978 have damage-tolerance
criteria built in to the manufacturers' repair philosophies. Airplanes
certificated before that date are regulated by FAA-approved
Supplemental Inspection Documents. The FAA then clarified for the
industry in 1989 that all transport category airplanes having the
damage-tolerance requirements of Sec. 25.571, amendment 25-45, as their
certification basis (i.e., post-1978 certificated airplanes) and those
with mandated Supplemental Inspection Document programs ( i.e., pre-
1978 certificated airplanes) must continue to maintain their damage-
tolerance characteristics when repaired or modified in any way.
Industry has been aware of this policy since that time. Thus, the
damage-tolerance assessment of repairs is already being done; it is not
a new concept. The RAG's have been under development for many years
and, during that development, the manufacturers of the affected
airplanes have consulted with operators.
Similarly, another commenter requests that additional time be
provided before implementation of the assessment program so that
regulated aviation community can review, understand, comment on, and
assimilate the RAG documents. The commenter claims that ``FAA's
aggressive schedule on the instant rulemaking has resulted in placing a
lot of pressure on the airframe manufacturers to publish the RAG
documents as soon as possible.'' The commenter asserts that, because of
this, the documents are of poor quality, with obvious gaps and numerous
inconsistencies between them. The commenter maintains that there is a
``compelling need'' to have these documents reviewed for completion and
for inconsistencies within and among them prior to starting the clock
for compliance.
The FAA does not concur. Numerous operators have participated in
the development of this rule, and have worked closely with the
manufacturers in the development of the RAG's. During various working
group meetings, the FAA raised the issue of inconsistencies between
documents; however, the operators represented at the meetings did not
raise any concerns about this. The FAA does not agree that granting
more time before implementing this rule will result in the timely
resolution of inconsistencies; as long as the repair assessment
guidelines meet the intent of the rule, the guidelines are not required
to be identical.
Implementation Times
One commenter requests clarification concerning the implementation
times of the repair assessment for new repairs. The commenter questions
what implementation period would apply for new repairs, assuming that
an airplane already has surpassed the flight cycle implementation time
specified for that model, and assuming that the operator has already
assessed every applicable repair under the proposed rule.
The FAA clarifies this issue by noting that the operator is
required to incorporate an FAA-approved repair assessment program into
its maintenance or inspection program, and that this program must
include a provision for addressing new repairs. As stated in the final
rule, for airplanes that have already exceeded the specified
implementation time, the maintenance program must be revised to
incorporate the repair assessment program within a year after the
effective date of this final rule. Once the program is revised,
operators are required to comply with it thereafter, under normal
maintenance rules. Therefore, there is no separate ``implementation
time'' for new repairs.
Another commenter requests clarification on the definitions of
various phases of the repair assessment program described in the Boeing
Model 727 RAG document, D6-56167. Since this commenter's questions are
not specifically relevant to this final rulemaking action, they are not
included in this preamble. However, the FAA has responded directly to
the commenter and a copy of the detailed response is contained in the
docket.
Determination of Inspection Intervals
One commenter questions why the proposed rule holds airplanes with
mechanical fuselage joints to the same inspection intervals as those
whose fuselage joints are assembled with adhesives. The commenter
implies that the inspection intervals should be different for each type
of these airplanes.
The FAA does not concur. The final rule does not specify any
explicit interval for repetitive inspections. Those intervals will be
developed based on what is determined to be appropriate for the
particular design features of the airplane. These intervals will be
specified in the model-specific RAG
[[Page 24118]]
documents and will be subject to approval by the cognizant FAA Aircraft
Certification Office. The only aspect that all airplanes will be held
to is that the inspection intervals must ensure that damage is detected
and corrected before failure of a structural repair could occur.
Another commenter requests that the FAA issue a determination in
advance stating that the results of SID inspections could serve as an
alternative means of compliance with the proposed rule. The commenter
asserts that it is unclear how to address an apparent conflict where
damage-tolerance analysis done under a SID program, which is mandated
by an AD, might render a different inspection schedule from the
guidelines in the RAG document.
The FAA does not concur with the commenter's request. The FAA
understands that the commenter's concern arises from a scenario such as
the following:
A repair to a principal structural element (PSE) has
been accomplished previously.
The operator has an inspection schedule, as part of its
SID program, for the repaired PSE based on damage-tolerance
analyses.
While assessing the repair of a PSE in accordance with
the new RAG document, the operator finds that the inspection
schedule under the RAG is more conservative than the SID (i.e.,
shorter inspection intervals, more frequent inspections).
The FAA does not consider it either necessary or appropriate to
issue ``an advance determination'' that SID inspection results could
serve as an alternative method of compliance to the rule for, in fact,
they may not. As stated in the preamble to the notice and this final
rule, there is the potential that there will be some situations where
requirements of the RAG do not agree with those of an AD (especially if
the AD were written to address a modification to the airplane made by
someone other that the original manufacturer). In those cases, the
Federal Aviation Regulations would require that compliance be shown
with both the AD and this rule. Such a ``dual compliance'' situation
can be avoided in the long term by working with the manufacturer, if
that is the source of difficulty, or by securing approval of an
alternative method of compliance with the AD. In the short term,
however, accomplishment of the earlier threshold, the shorter repeat
inspection interval, or the more stringent rework/replacement schedule
would always constitute compliance with the less stringent requirement.
Thus, the operator would not be faced with an unresolvable conflict.
Escalation of Inspection Intervals
One commenter, an airframe manufacturer, requests that the proposed
rule be revised to allow a ``less restrictive policy'' with regard to
escalating the repetitive inspection intervals required by the program.
This commenter notes that, in approving the RAG documents developed for
affected airplanes, the FAA stated that it would approve provisions
allowing for escalation of repeat inspection intervals for an
individual airplane, but on the condition that each escalation is first
approved by the FAA airworthiness inspector on a case-by-case basis. In
approving these documents, the FAA indicated that it would not allow
(1) any escalation of the inspection threshold or (2) a generally
applicable escalation of repetitive inspection intervals.
The commenter maintains that the requirement of gaining prior
approval by the FAA airworthiness inspector on a case-by-case basis is
more restrictive than similar requirements currently required by other
FAA-approved programs, such as the SSID and the CPCP. The SSID program,
for example, allows the repeat inspection interval for individual
airplanes to be increased by up to 10% of the normal interval.
Additionally, the CPCP program allows the repeat inspection interval to
be increased by up to 10% (but not to exceed 6 months) in order to
accommodate unanticipated scheduling requirements; the operator needs
only to notify the cognizant FAA Principal Inspector (PI) in writing of
any extension made. This commenter suggests that the approach taken by
these programs appears to be a more reasonable method of addressing the
escalation of inspection intervals, and asserts that the inspection
intervals found in the RAG's all could be increased by 10% and still
provide adequate inspections to maintain safety. The commenter requests
that the proposed rule be revised to allow the same escalation policy
provided in for the SSID and CPCP programs be applied to the repair
assessment program.
The FAA does not concur with the commenter's request. This position
is based on experience that the FAA has gained over the years in trying
to administer the SSID and CPCP programs. In trying to allow for some
flexibility in those programs to accommodate scheduling and other
situations, the FAA has found that some affected operators are very
confused about the process for escalating the repeat inspection
intervals; the FAA also has found that some affected operators abuse
the process. The operators themselves pointed this out in the numerous
meetings that were held during the development of the repair assessment
program. In September 1997, the Manager of the Transport Airplane
Directorate issued a memorandum to all cognizant ACO's providing
guidance for development of the RAG's. That memorandum addressed areas
of concern regarding inspection intervals and established two policies:
Inspection thresholds shall be fixed and there should
be no provisions for escalation of them; and
Repeat intervals can be escalated up to either 10% or a
specific time interval specified by the manufacturer, whichever is
less. Escalation must be approved by the airworthiness inspector on
a case-by-case basis to accommodate one-time scheduling conflicts.
One of the purposes of the memorandum was to ensure standardization
of the application of the program across FAA offices. Further, because
many operators have various airplane models and multiple TC holders are
involved, there was a great desire on the part of the operators to have
the repair assessment program standardized as much as possible and be
less confusing. As stated previously, operators have been involved in
many meetings with the FAA and TC holders as the RAG's were being
developed; therefore, they are aware of the policy regarding escalation
and have indicated their agreement with that policy.
New Repairs
One commenter's understanding of the proposed rule is that it would
allow the use of the RAG document as a tool to evaluate new repairs.
The commenter does not believe, however, that this is in line with the
intent of the repair assessment program, which is to serve as a
``catch-up'' process to ``remedy'' old repairs and not as a design tool
for new repairs. If it is possible to use the RAG to assess new
repairs, the commenter foresees a situation where it could be possible
to install repairs with a bad damage-tolerance capability and, through
the RAG document, to demonstrate that the repair is still ``safe''
during a certain period. The commenter maintains that, if the proposed
rule were to be revised to require that the general guidelines for
designing repairs--as defined in the SRM--are followed for the new
repair installed, then the situation described will certainly not
occur. The commenter requests that the proposed rule state that the
damage-tolerance assessment of a ``new repair'' will have to be done
through the current recommendations found in the relevant part of the
SRM,
[[Page 24119]]
or the repair assessment will have to be done by a design office (TC
holder or other) and approved by the FAA following current procedures.
This commenter justifies this request by stating that all the
repairs installed on the pressurized shell boundary will have to be
assessed for their damage-tolerance characteristics. The commenter
states that, in order to avoid design and installation of ``Category
C'' repairs (temporary repairs that will need to be reworked or
replaced prior to an established time limit), operators will need to
use the repair instructions and methods described in the updated SRM
guidelines. The commenter maintains that this will compel the
manufacturer to update its SRM and not to rely only on the RAG document
to fulfill its obligations to the operators under this final rule. If
the SRM is used in lieu of the RAG, the approach will be preventive
instead of curative and this will, in a certain manner, increase the
level of safety.
The FAA recognizes the commenter's point, but does not concur that
a revision to the rule is necessary. Existing regulations [e.g., 14 CFR
43.13(b)] already require that all repairs restore the airplane to at
least its original or properly altered condition, and those
requirements are not affected by this final rule. As discussed
previously, this rule simply ensures that the durability of repairs is
assessed, and that necessary inspections and rework are accomplished in
a timely manner. The TC holders have been devoting resources to update
their SRM's, but this process has not proceeded as quickly as hoped;
therefore, as an interim measure, the operators can use the RAG
document to evaluate their repairs. The FAA considers that use of the
RAG document to evaluate temporary repairs will not compromise the
repair assessment program required by this final rule.
Classification of Major/Minor Repairs
One commenter questions whether any levels of rework or repairs
resulting from the inspections that would be required under the
proposed rule would be classified as ``major repairs.'' The commenter
suggests that this item be clarified.
The FAA responds by noting that there should be no change regarding
the classification of either ``major'' or ``minor'' repairs based on
the requirements of the new rule. Generally, repairs to PSE's meet the
definition of ``major'' repairs.
Supplemental Type Certificate Holders
One commenter raises a concern about Supplemental Type Certificate
(STC) holders and any commitment that they would owe to operators in
developing the repair assessment program. Under the proposed rule, an
STC holder could quite easily withhold assistance and the operator
would have to acquire an FAA-approved RAG independently. The commenter
requests that the rule be revised to require the TC holder to assist
the operator in assessing whether a repair to an STC modification can
be evaluated through the use of the manufacturer's RAG, based on
similarity. The TC holder's assistance should be required to gain
approval from the operator's Principal Maintenance Inspector (PMI) or
other cognizant airworthiness inspector. If the rule is not changed and
the support of the STC holder is not required, significant additional
costs could be incurred by the operators.
The FAA does not concur with the commenter's request that the TC
holders be required to assist the operators in assessing repairs to STC
modifications. Under this rule--and operating rules in general--the
operator is ultimately responsible for maintenance of its fleet. As
discussed in the NPRM, the operator is required to establish a program
to assess repairs to modified structure, and may be compelled to
contract for the necessary expertise to develop that program.
Relationship of Rule to Operation Specifications
One commenter states that, in a number of places in the preamble to
the notice, the phrase, ``an operator's operation specification or
maintenance program'' is used correctly, while in other places only the
term ``operation specification'' is used, which is incorrect. Small
operators can be expected to have their maintenance programs
incorporated into Section D of the airplane's operation specifications.
However, large operators, especially those permitted reliability-based
maintenance programs, have only a chapter of their Maintenance Manual
listed in Section D of the operation specifications. The commenter
requests that the proposed rule be revised to clarify this.
The FAA concurs. The FAA has removed the term ``operation
specification'' and replaced it with ``maintenance program'' in the
appropriate areas of the text of the final rule.
Adjustment for Pressure Factor
One commenter expresses concern that the 1.2 adjustment factor for
the Boeing 747SR touch and go allowance, and the allowance for flights
with less than 2.0 PSI, were removed from the Boeing 747 RAG document.
The commenter requests that the rule specifically permit the use of
these pressure factor allowances in the RAG document.
The FAA does not concur. The FAA is concerned about tracking
individual airplanes and their usage in order to comply with such an
allowance. If the operator submitted a plan on how the airplanes would
be tracked and how this information would be transferred in the event
the transfer of such an aircraft, the FAA would consider a proposal
that could be approved on a case-by-case basis.
Recordkeeping
Several commenters raised concerns about recordkeeping that could
necessarily accompany the implementation of the requirements of the
proposed rule. In the preamble to the notice, the FAA indicated that
the rule would not impose any new FAA recordkeeping requirements, and
that the current operating regulations (e.g., 14 CFR 121.380,
``Maintenance recording requirements'') already impose adequate
recordkeeping requirements that would apply to the actions required by
the rule. As discussed below, certain commenters contest that
statement:
Transfer of Repair Data. One commenter states that Sec. 121.380 is
not an adequate regulation either to mandate the transfer of repair
data from one owner to another, or to ensure the transfer of inspection
data resulting from the new regulation. The commenter points out that
Sec. 121.380 requires that data be retained for only certain periods of
time (usually one year), not the lifetime of the airplane. This poses a
problem if operators are required to be knowledgeable of all the
repairs previously performed on every airplane in its fleet. The
commenter asserts that the proposed rule fails to take into
consideration that ``over half of the commercial airplanes in the U.S.
are leased and, therefore, subject to transfer between two U.S.
operators.'' Those involved in such transfers today are well aware that
the ability to obtain repair data is dependent on the individual
recordkeeping standards of the operators--how long or how well the
operator has kept the data. Moreover, the current regulations do not
assist in the acquisition of such data.
[[Page 24120]]
The commenter suggests that Sec. 121.380 should be revised to require
the retention of records for the lifetime of the aircraft or to exempt
repair data from the current ``one-year destruction'' rule.
The FAA acknowledges the commenter's observations, but does not
agree that there is a need either to impose new recordkeeping
requirements in conjunction with this rulemaking, or to revise
Sec. 121.380. In every case, when an operator purchases an aircraft, it
is the operator's responsibility to ensure that the aircraft complies
with the operational requirements prior to adding it to its
certificate. If pertinent data are not available at the time of the
purchase, it normally is the operator's responsibility to go about
obtaining the necessary information. In the case of this final rule, if
the repair data are not available, an operator may be required to
perform an assessment of the aircraft to establish the damage-tolerance
of the repairs to the fuselage pressure boundary. The operator could
then retain records of this assessment. Generally, the FAA anticipates
that availability of necessary repair records will significantly
enhance the value of affected airplanes because of the degree to which
such records will simplify airplane transfers. Therefore, it is likely
that, as a matter of commercial practice, operators will retain those
records indefinitely.
Information Actually Retained. One commenter states that, while
most U.S. operators agree that records covering ``unsuperseded''
routine maintenance functions must be maintained, they do not all agree
that ``non-routine functions resulting from these inspections are
equally important.'' In short, a record that documents the performance
of a repair assessment inspection may be kept, but any rework, repairs,
etc., resulting from that inspection may not. This is especially true
in cases where operators have totally automated their record systems.
The commenter suggests that the proposed rule, in actuality, will
impose new recordkeeping requirements since operators will have to
maintain repair data resulting from inspections.
The FAA acknowledges the commenter's comments. However, the FAA
reiterates that, as stated previously, there are no new recordkeeping
requirements mandated by this rule. As in any case, operators are
required to maintain satisfactory evidence that they are in compliance
with the regulations; this new rule requires nothing in addition to
this.
New Methods To Retain/Maintain Repair Data
One commenter states that it has developed an inexpensive software
program and has a ``U.S. Patented Process'' to track new and old
repairs completed on aircraft by using digital cameras. The commenter
suggests that this product would be an excellent way of tracking
aircraft repairs for the proposed repair assessment program.
The FAA infers from this comment that the commenter is suggesting
the rule be revised to require the use of such software to maintain
repair data. The FAA understands that this software and others like it
currently are available on the market. Operators could certainly use
these types of products to simplify the retention of the necessary
information needed to demonstrate compliance with this rule. However,
no change to the rule is necessary to indicate this.
Enforceability of Sec. 129.32
One commenter questions the enforceability of the proposed
Sec. 129.32 on operators that are not subject to FAA regulations,
specifically non-U.S. operators. The commenter states that, for
example, although maintenance program provisions specified in part 129
may be issued by the FAA and provided by the airplane lessor (in the
U.S.) to an international lessee, there is ``no way to enforce [the
lessee's] adherence'' to the requirements of that regulation. The
commenter asserts that ``there are no recordkeeping enforcement
provisions for part 129 operators'' and, since ``they do not operate to
14 CFR, the proposed rule would be meaningless to them.'' The commenter
fears that this could result in the invalidation of the leased
airplane's Standard Airworthiness Certificate when it is returned to
the U.S.
The FAA does not concur. The rule will be enforceable with regard
to part 129 foreign air carriers operating U.S.-registered aircraft
into the U.S. As discussed in the preamble to the notice, the new
repair assessment program required by Sec. 129.32 will be approved as
part of the foreign air carrier's operations specifications (the
maintenance programs will be incorporated into or listed in Section D
of the operation specifications). In accordance with Sec. 129.11, part
129 foreign air carriers must conduct their operations in accordance
with the operations specifications.
If foreign persons operating U.S.-registered aircraft in common
carriage or foreign air carriers operating outside the U.S. do not
maintain the aircraft in accordance with U.S. airworthiness standards,
or cannot present adequate documentation of such maintenance, then the
airworthiness certificate will be invalidated. A prudent aircraft owner
will insist, as a matter of contract, that the repairs and maintenance
are adequately documented so that, when the lease is terminated or the
airplane sold, the airplane can retain its airworthiness certificate.
Impact on International Trade
One commenter raises three issues concerning the International
Trade Impact Assessment that appeared in the preamble to the notice,
and the intended effect of the proposed rule on the import and export
of airplanes:
First, the commenter questions whether the International Trade
Impact Assessment took into account the fact that other nations could
emulate this rulemaking action and establish their own similar repair
assessment programs. Usually foreign operators maintain considerably
better records for such things as repairs than do U.S. operators and if
the proposed rule does not require ``any new recordkeeping
requirements,'' U.S. operators may be hard-pressed to provide adequate
data to support the other country's repair assessment program. The
commenter implies that this may be a hindrance to the export of
airplanes to those countries.
Second, the commenter asks that, if an imported airplane has never
been inspected under a repair assessment program, (1) would its
baseline inspection suffice, or (2) does the FAA/AAWG assume that the
airplane's next U.S. part 121 operator would be responsible for
bringing it up to the standards of the proposed rule prior to
operation? The commenter notes that there is no FAA checklist of items
that require action prior to issuance of a Standard Airworthiness
Certificate, but an airplane being imported must meet the requirements
of parts 21, 43, and 91 to obtain a Standard Airworthiness Certificate.
The commenter states that the proposed change to Sec. 91.410 would
establish deadlines that would preclude the issuance of the certificate
prior to an airplane being added to a part 121 operator's fleet.
Third, the commenter considers that the AAWG did not possess the
necessary expertise that would come from experience in the transfer of
airplanes, to reach the conclusion that the proposed rule would not
affect the import or export of airplanes to or from the U.S. The
commenter implies that the International Trade Impact Assessment
[[Page 24121]]
statement that appeared in the preamble to the notice is incorrect.
The FAA does not concur with the commenter. The information
provided in the International Trade Impact Assessment states only that
the proposed rule would not constitute a ``barrier to international
trade, including the export of American airplanes to foreign countries
and the import of foreign airplanes into the United States.'' Despite
the condition that an airplane is in when imported to the U.S., a part
121 operator will still be responsible for ensuring compliance with the
repair assessment requirements--as well as with every other applicable
regulation--prior to putting the airplane into operation. While this
may entail additional work on the part of the operator, it does not
constitute a ``barrier to international trade.'' In fact, it is general
practice for the importing operator to ensure the airplane is
compliance with all applicable regulations of the importing country.
Regarding the effect on exports, as indicated previously, the FAA
anticipates that, as a commercial practice, operators will retain
repair assessment records to facilitate future transfers. Assuming that
foreign civil aviation authorities adopt requirements similar to this
final rule, these records would also be sufficient to meet those
requirements.
As for the qualifications of the AAWG, the FAA points out that the
AAWG is comprised of representatives from the aviation industry both in
the U.S. and foreign countries; this includes manfuacturers, airlines,
leasing companies, industry associations, unions, and non-U.S. civil
aviation authorities. These representatives are some of the most
experienced individuals in aviation worldwide who possess far-reaching
expertise in numerous relevant areas. Their qualifications are
incomparable and, as demonstrated in their work at part of AAWG, their
knowledge and capabilities are considerable.
Proposed Regulatory Evaluation
One commenter states that the proposal grossly underestimates the
cost impact it will have on operators. The commenter states that one
operator, who manages a fleet of about 10 percent of the affected U.S.
fleet, has assessed the potential impact of the proposed program on its
staffing requirements as follows:
If only 12 repairs per airplane require assessment
under the program, the total number of repairs for a fleet of 356
airplanes will be 4,272.
Approximately 4 engineering hours (at $55 per hour)
would be required for each initial assessment. Based on this figure,
the total number of work hours could be as many as 17,088, costing
over $900,000.
If half the number of repairs would require evaluation
beyond the scope of existing manufacturers' documents, engineering
support would be twice the level of the ordinary initial assessment
and, thus, an additional cost of $900,000 could be expected.
Repetitive inspections resulting from the program will
add another $2.3 million in costs and over 10,000 hours of out-of-
service time.
The total estimated cost for this single operator is at least $4.1
million, and the loss of service of three airplanes out of the fleet
for the remainder of their operational lives. If the airlines elects to
replace the lost capacity, additional costs on the order of $300
million will be incurred. While one carrier may elect not to replace
lost capacity and allow the lost traffic to go to competitors, the
industry as a whole cannot take this strategy. If all operators opted
not to add capacity, load factors would have to grow. At over 70%, load
factors are already at an all-time high, and production is at its
limits. As a result, there would be a severe degradation in service to
the public, as more travelers would be forced into second and third
choices involving indirect routing and higher fares. The implied total
U.S. cost would then be at least $40 million, and potentially as much
as $3 billion more to replace lost capacity.
The commenter avers that cost analysis indicated by FAA fails to
recognize that the extensive repair analyses and additional repetitive
inspections on airplanes will force many airplanes to be pulled out of
normal rotations to complete the required work; the resulting out-of-
service time will wreak havoc on airline schedules. The commenter
points out that the potential impact on system capacity has not been
addressed by the FAA and should be adequately treated prior to adopting
the proposed rule. Moreover, the commenter states that the FAA does not
address the potential redundancy of the requirements with regard to
existing Supplemental Structural Inspection Program and airworthiness
directives that also result in damage-tolerance evaluation of
structural repairs. The commenter requests that the FAA initiate and
complete a more formal cost-benefit evaluation of the proposed action,
and make it available to the public for review and comment, prior to
taking final action.
The FAA does not concur with the commenter's conclusions concerning
the economic impact of this rule, or the need to provide additional
time for public comment on the cost-benefit evaluation. A summary of
the final economic evaluation appears in the Regulatory Evaluation
Summary section of this document. The summary provides details of the
FAA's final determination as to the economic impact and cost-benefit of
this final rule. The full final economic evaluation can be found in the
public docket. The FAA's response to specific points brought up by the
commenter in its arguments is as follows.
The commenter used the figure of 4 engineering hours as the number
of hours necessary to carry out each initial assessment. According to
the commenter, this figure was based on one operator's estimate. The
FAA used a figure of 1 engineering hour for an initial assessment; this
figure was based on estimates provided by members of the AAWG group
associated with this rule, who had arrived at the figure from the input
from several operators and others in pertinent aviation fields. The FAA
considers the 1 hour figure more feasible due to the fact it represents
data obtained from a wider range of entities affected by this rule.
The commenter estimated that repetitive inspections would add
another $2.3 million in costs and over 10,000 hours of out-of-service
time. The FAA does not consider those figures to be appropriate. With
regard to the $2.3 million, the commenter made no mention of using
discounted values; therefore, the FAA assumes that the $2.3 million
figure is represented in current values/prices. However, the
inspections are to take place in the future--and they would need to be
discounted to present values. This would substantially reduce their
magnitude in present value.
With regard to the 10,000 hours of out-of-service time, the
commenter made no mention of accomplishing the inspections required by
the rule during a regularly-scheduled C- or D-check. The use of the C-
and D-check. The use of the C- and D-checks to carry out inspections
would significantly reduce or effectively eliminate the out-of-service
time.
In its proposed economic evaluation, the FAA carried out cost
estimates for operators by using 1 hour for the accomplishment of the
initial assessments, and 2 hours for carrying out supplemental
inspections. The assessments and inspections also were assumed to take
place during C- or D-checks. The cost estimates thus derived were
subsequently discounted to present day values--since the assessments
and inspections would not
[[Page 24122]]
take place today but at some years in the future.
The commenter considers the rule to be largely redundant and not
needed because the current certification regulations for new airplanes,
and the Supplemental Structural Inspection Programs (SSIP) for older
airplanes, already accomplish the intent of a damage-tolerance
assessment of repairs that would be required by the rule. The FAA does
not concur with the commenter's assumption and has explained, in both
the preamble to the notice as well as this preamble, the reasons why
this rule is essential. To reiterate: The Supplemental Structural
Inspection Programs for existing airplanes, including nearly all of the
airplane models affected by this new rule, were mandated by
Airworthiness Directives (AD) beginning in 1984. The majority of those
AD's did not attempt to address issues relating to the damage tolerance
of repairs that had been made to the airplanes; therefore, one of the
objectives of this new rule is to provide that same level of assurance
for areas of the structure that have been repaired.
The practice of damage-tolerance methodology has evolved gradually
over the last 20-plus years. Because a regulatory requirement for
damage-tolerance was not applied to airplane designs type certificated
before 1978, the damage-tolerance characteristics of repairs that
currently exist on airplanes may vary widely and are largely unknown.
Further, some repair designs contained in the airplane manufacturers'
Structural Repair Manuals (SRM) were not designed to current standards,
and repairs accomplished in accordance with those SRM's may require
additional inspections if evaluated using current methodologies. This
new rule will ensure that those inspections are accomplishments and
that repairs are brought up to standards, if necessary.
Terminology Changes in Final Rule
The FAA has revised certain terminology that appeared in the
proposed introductory text of Sec. 91.410 and Sec. 125.248.The
provisions of those sections, as they appeared in the proposal,
included the phrase ``No certificate holder may operate * * *''
However, in this final rule, that phrase has been replaced with ``No
person may operate * * *'' in order to conform with the terminology
used throughout parts 91 and 125.
Additionally, the FAA has replaced this same terminology in the
next of Sec. 129.32 with ``No foreign air carrier or foreign persons a
U.S.-registered airplane may operate * * *'' This change has been made
in order to correctly reflect the operators who are affected by this
section of the regulations.
The FAA also has revised certain other wording in the introductory
text of Secs. 121.370, 125.248, and 129.32. The proposed text in each
of those sections stated that none of the affected airplanes could be
operated beyond the specified time(s) ``* * * unless its operation
specifications have been revised to reference repair assessment
guidelines * * *'' This text in the final rule has been revised to
state ``* * * unless operations specifications have been issued to
reference repair assessment guidelines * * *'' This change is necessary
to corrently reflect the interface of this rule with the operations
specifications process.
Additionally, in the proposal, the introductory text for each of
the proposed regulations indicated that approval of the repair
assessment guidelines could be granted only by the FAA Aircraft
Certification Office (ACO) having cognizance over the type certificate
for the affected airplane. The FAA has revised this text in the final
rule to indicate that there are FAA offices other than ACO's that have
cognizance over type certificates and, therefore, those office may
approve the repair assessment guidelines.
Paperwork Reduction Act
In accordance with the Paperwork Reduction Act of 1995 [44 U.S.C.
3507(d)], the FAA has determined that there are no requirements for
information collection associated with this final rule.
International Compatibility
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to comply with
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA
determined that there are no ICAO Standards and Recommended Practices
that correspond to these regulations.
Regulatory Evaluation Summary
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
Office of Management and Budget (OMB) directs agencies to assess the
effect of regulatory changes on international trade. And 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 private sector, or $100 million or
more annually (adjusted for inflation).
In conducting these analyzes, the FAA has determined that this rule
is not ``a significant regulatory action'' as defined under section
3(f) of Executive Order 12866 and, therefore is not subject to review
by the Office of Management and Budget. The rule is not considered
significant under the regulatory policies and procedures of the
Department of Transportation (44 FR 11034, February 26, 1979). This
rule will not have a significant impact on a substantial number of
small entities and will not constitute a barrier to international
trade.
These analyses, available in the docket, are summarized below.
Costs to Manufacturers
This section presents the FAA's estimate of costs to the four
manufacturers of the airplane models affected by the rule. The FAA has
conservatively included estimates of costs to non-U.S. manufacturers
(i.e., Airbus Industrie, British Aerospace, and Fokker Aircraft B.V.),
although only those costs to U.S. manufacturers are required to be
estimated. Manufacturers will incur one-time, ``set-up'' costs to:
1. Revise their SRM and to develop RAG's to reflect damage-tolerant
repair considerations:
2. Publish the revised SRM and the RAG's; and
3. Train their engineers, personnel of the operator, and the FAA to
conduct repair assessments.
Manufacturers also will incur continuing program maintenance costs
of:
Maintenance of records for the program,
Additional training and subsequent revisions to the
SRM, and
Assessments of unusual repairs that are not described
in the published guidelines.
The total one-time, set-up costs are estimated to be $10.8 million
in the year 2000. Total annual, recurring costs for the years 2001
through 2022 are estimated to be $28.7 million, or about $1.3 million
per year. The total non-discounted costs of the rule to affected
manufacturers are estimated to be $39.5 million over the years 2000
through
[[Page 24123]]
2022, or $25.2 million discounted to present value at 7 percent.
The estimates are based on an effective date of 2000. The FAA
assumes that the manufacturers' costs of setting up their repair
assessment programs would be incurred in the year 2000, and that annual
costs would be incurred each year beginning in 2001 through 2022. The
setting-up costs include the cost of revising Structural Repair Manuals
and developing repair assessment guidelines for some models, the cost
of publishing these documents, and the cost of training. Costs are
expressed in constant dollars.
Costs to Operators
Operators will incur costs to
Train inspectors,
Integrate the repair assessment program into the
maintenance program for each affected model,
Conduct repair assessments and supplemental
inspections, and
Maintain records of assessments and inspections.
Because repair assessments and supplemental inspections are assumed
to be conducted during regularly scheduled C- and D-checks, the FAA has
not attributed any downtime costs. The FAA estimates that it takes
between 25 and 30 people, working three shifts per day, 10 to 14 days
to conduct a C-check. The FAA also estimates that it takes between 30
and 40 people, working three shifts per day, three to seven weeks to
conduct a D-check. The relatively brief time to conduct a repair
assessment or a supplemental inspection check could be incorporated
into a C- or D-check without additional loss of service.
Fleet Data and Noise Restrictions: The FAA used Airclaims
fleet data to estimate operators' costs to conduct repair assessments
and inspections. Airplane-specific cumulative and current annual flight
cycles and flight hours for all U.S.-registered airplanes affected by
the program were used to predict each airplane's ``threshold'' date
(i.e., the date on which the proposed flight cycle implementation time
is reached). The analysis includes affected U.S.-registered airplanes
that are operated by foreign entities. The threshold, or flight
implementation time, is 75 percent of the original equipment
manufacturer's design service goal. Information received from several
of the affected manufacturers confirmed the accuracy of the database.
Noise restrictions on airplanes also have an impact on the estimate
of the number or airplanes affected by the rule. Because of noise
restrictions, as of January 1, 2000, Stage 1 and Stage 2 airplanes will
not longer be allowed to operate in the continental United States; and
the FAA assumes that U.S. operators will either retire or sell to
foreign entities those models that are exclusively State 1 or Stage 2
airplanes. This relates to airplanes such as the BAC 1-11 and Fokker F-
28.
The database of airplanes used for this analysis includes data that
are effective as of January 1, 1999. To carry out calculations, the FAA
assumed that airplanes in that database that still had Stage 2 hush
kits would not be equipped with Stage 3 hush kits by the end of 1999.
These airplanes were, thus, not included in the calculations. The FAA
recognizes that an underestimate of the number of airplanes with Stage
2 hush kits may thus occur; however, the FAA believes that number to be
small and indeterminate. This estimate includes both N-registered
airplanes operated by airlines as well as by non-airline entities, but
does not include any additional airplanes that might be imported. It
also does not include future production (i.e. ``new'') airplanes that
may reach the threshold before 2022, the estimate of which would be
highly tenuous and whose present value costs will be low or zero.
Repair Assessment and Supplemental Inspection Costs: The
activities involved in the entire repair assessment program can be
classified into three basic stages. The first stage requires that a
certificate holder (i.e., an operator) incorporate a repair assessment
program into this maintenance or inspection program by the time that an
airplane, for that particular model, reaches its flight cycle
implementation time (e.g., the threshold) or within one year from the
effective date of the rule--whichever occurs later. The actual outcome
between these two possibilities is affected by the actual number of
flight cycles in relationship to the design service goal of the
airplane at the effective date of the rule.
The second stage involves repair assessments. This work is to be
conducted, for individual airplanes, within the D-check or C-check
flight cycle interval after the first stage. The D-check interval is
used for airplanes whose flight cycles will not have exceeded their
design service goal by the effective date of the rule. The C-check
interval is used for those airplanes that will have exceeded their
design service goal by the effective date of the rule. In this second
stage, the previous repairs to the fuselages of the affected airplanes
are assessed, by operators' maintenance personnel, to check whether
they meet the damage-tolerance criteria. If they do, additional work is
not required. If they do not, these repairs are to be repaired again
and brought up to the expected quality.
During the third stage, these repairs are to be inspected at the C-
check interval of that particular airplane model.
With regard to specific chronology, given an expected effective
date of the rule of 2000 and the requirements in the rule, the repair
assessment will be conducted at the next heavy maintenance D-check
after January 1, 2001, or after the threshold, whichever occurs later.
For those airplanes that have exceeded the design service goal, by the
effective date of the rule. The repair assessment will be conducted at
the next C-check after January 2001.
The AAWG estimated the number of repairs for airplanes, in each
affected airplane model, that would require assessment at the
appropriate date, and the number of those repairs that would require
supplemental inspections. The AAWG also estimated that it would take 1
hour to assess a repair and 2 hours to inspect a repair. For
supplemental inspections, the AAWG estimated that \1/2\ of the repairs
would require inspections during every C-check, while the other half
would require inspections during every fourth children-check.
Manufacturers and operators provided information on the average number
of flight hours between C-checks and D-checks, by affected model. The
AAWG estimated that affected airplanes would continue to be operated
for 10 years beyond the dates of their repair assessments.
The FAA has estimated operator compliance costs for repair
assessment and supplemental inspections through the year 2022 to the
$17.4 million, or $6.0 million discounted to present value.
Training Costs: Operators of affected U.S.-registered
airplanes will incur costs in order to train their maintenance
personnel to assess and inspect repairs. Moreover, it is expected that,
rather than train their own maintenance personnel, operators with only
a few affected airplanes will likely contract out assessments and
inspections with other operators whose maintenance personnel have been
trained to conduct these activities.
The FAA assumes that training costs for operators' maintenance
personnel would be incurred in 2000. Moreover, in order to account for
turnover among maintenance personnel trained for repair assessment, the
FAA estimates that operators would incur annual training costs, equal
to 5 percent of the 2000 training costs, for each year from
[[Page 24124]]
2001 through 2022. Operators' costs for training are described in more
detail in the full regulatory evaluation.
The FAA estimates that total training costs over the years 2000
through 2022 will be $869,842, or $643,279 discounted to present value.
Administrative Costs of the Repair Assessment Program: The
rule will require each affected operator to integrate a repair
assessment program into either its maintenance program (for affected
airplanes operated under part 121 or 129) or its inspection program
(for affected airplanes operated under part 91 or 125) by the time the
threshold is reached or within one year from the effective date of the
proposed rule, whichever is later. The repair assessment program can
include such information as:
The scope of the assessment;
Relevant Airworthiness Directives (AD) and Service
Bulletins (SB);
The means to identify, assess, and inspect repairs; and
Procedures to maintain records for each airplane's
repair survey, assessments, and supplemental inspections.
Costs to operators for program administration are estimated to
total $0.7 million, or $0.3 million discounted to present value.
Based on estimates of manufacturers, operators, the AAWG, and the
FAA, over the years 2000 through 2022, operators of airplanes affected
by the proposed rule are expected to incur total costs of $19.0
million, or $6.9 million discounted to present value. Repair
assessments and supplemental inspection costs account for about 92
percent of total costs and 86 percent of present value costs.
Costs to the FAA
The rule requires FAA approval of repair assessment programs.
Aircraft Certification Offices (ACO) will review repair assessment
guidelines for airline and non-airline operators. The FAA Principal
Maintenance Inspectors (PMI) will review the maintenance programs for
their assigned airlines to ensure implementation and compliance with
the repair assessment program. In addition, PMI's and other FAA
inspectors also will be trained to conduct repair assessments and
supplemental inspections. It is estimated that the total cost to the
FAA will be $548,353, or $344,695 discounted to present value.
Total Costs of the Rule
Total costs of the rule to manufacturers, operators, and the FAA
are estimated to be $59.1 million over the years 2000 through 2022, or
$32.5 million in present value.
Benefits
Based on available data, no accidents have been caused by the
failure of structural repairs to airplanes of the models affected by
the rule. Nevertheless, these airplanes being operated beyond their
design service objective and the FAA has determined that the repair
assessment program is needed to maintain the continued airworthiness of
these aging airplanes. The FAA is unable to determine the number of
accidents that would be prevented by this rule. However, only one
serious accident needs to be avoided in order to offset the total cost
of the rule. Based on International Aircraft Price Guide [Summer 1994:
Airclaims Limited: London, England], the FAA estimated that the
weighted average value of an affected airplane is $10.8 million, in
constant dollars. Using a conservative load factor of 63 percent for
passenger airplanes and accounting for those airplanes that are
operated in cargo service, the weighted average number of occupants is
103. Using $2.7 million as the statistical value of a fatality avoided,
the average cost of an accident to an affected airplane resulting in
the loss of the airplane and half of its occupants, would be $150.9
million, including $1 million for accident investigation. If this
accident occurred halfway between the first and last year of repair
assessments in this analysis (i.e., between 2001 and 2022), the present
value of benefits is estimated to be $46.8 million.
Benefits Compared to Costs
The benefits of the rule are estimated at $46.8 million, at present
value, while the costs of the rule are estimated at $32.5 million at
present value. The FAA, therefore, has determined that if the rule
prevents one ``average'' accident, the repair assessment program will
be cost-beneficial.
Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) of 1980, 5 U.S.C. 601-612,
directs the FAA to fit regulatory requirements to the scale of the
business, organizations, and governmental jurisdictions subject to the
regulation. We are required to determine whether a proposed or final
action will have a ``significant economic impact on a substantial
number of small entities'' as defined in the Act. If we find that the
action will have a significant impact, we must do a ``regulatory
flexibility analysis.''
This final rule will affect manufacturers and operators of
airplanes, in the specified parts of the CFR. For both manufacturers
and operators, a small entity is currently defined as one with 1,500 or
fewer employees. None of the airplane manufacturers that are affected
by this final rule have employee levels that fall below this employment
threshold. Consequently, the FAA certifies that the final rule will not
have a significant economic impact on a substantial number of
manufacturers of airplanes.
Some operators, however, do have employee levels that fall below
the employment threshold. Consequently, calculations were carried out
to assess whether the rule will have a significant impact on a
substantial number of these operators. These calculations showed that
the annualized cost of the rule is very small in comparison to annual
revenues of the affected entities--considerably smaller than 1 percent
of their revenues. Consequently, the rule will not have a significant
impact on small operators.
International Trade Impact Assessment
The provisions of this rule will have little or no impact on trade
for U.S. firms doing business in foreign countries and foreign firms
doing business in the United States.
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, on the
relationship between the national Government and the States, or on the
distribution of power and responsibilities among the various levels of
government. Therefore, the FAA has determined that this rule does not
have federalism implications.
Unfunded Mandates Analysis
Title II of the Unfunded Mandates Reform Act of 1995 (the Act),
codified as 2 U.S.C. 1501-1571, requires each Federal agency, to the
extent permitted by law, to prepare a written assessment of the effects
of any Federal mandate in a proposed or final agency rule that may
result in the expenditure by State, local, and tribal governments, in
the aggregate, or by the private sector, of $100 million or more
(adjusted annually for inflation) in any one year. Section 204(a) of
the Act, 2 U.S.C. 1534(a), requires the Federal agency to develop an
effective process to permit timely input by elected officers (or their
designees) of State, local, and tribal governments on a proposed
``significant intergovernmental mandate.'' A ``significant
intergovernmental
[[Page 24125]]
mandate'' under the Act is any provision in a Federal agency regulation
that would impose an enforceable duty upon State, local, and tribal
governments, in the aggregate, of $100 million (adjusted annually for
inflation) in any one year. Section 203 of the Act, 2 U.S.C. 1533,
which supplements section 204(a), provides that before establishing any
regulatory requirements that might significantly or uniquely affect
small governments, the agency shall have developed a plan that, among
other things, provides for notice to potentially affected small
governments, if any, and for a meaningful and timely opportunity to
provide input in the development of regulatory proposals.
This rule does not contain a Federal intergovernmental or private
sector mandate that exceeds $100 million in any one year.
Environmental Analysis
FAA Order 1050.1D defines FAA actions that may be categorically
excluded from preparation of a National Environmental Policy Act (NEPA)
environmental assessment or environmental impact statement. In
accordance with FAA Order 1050.1D, appendix 4, paragraph 4(j), this
rulemaking action qualifies for a categorical exclusion.
Regulations Affecting Intrastate Aviation in Alaska
Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat.
3213) requires the Administrator, when modifying regulations in Title
14 of the CFR in a manner affecting intrastate aviation in Alaska, to
consider the extent to which Alaska is not served by transportation
modes other than aviation, and to establish such regulatory
distinctions as he or she considers appropriate. Because this amendment
applies to the operation of certain transport category airplanes under
parts 91, 121, 125, and 129 of Title 14, it could affect intrastate
aviation in Alaska. Because no comments were received regarding this
regulation affecting intrastate aviation in Alaska, the FAA will apply
the rule in the same way that it is being applied nationally.
Energy Impact
The energy impact of the rule has been assessed in accordance with
the Energy Policy and Conservation Act (EPCA) Pub. L. 94-163, as
amended (43 U.S.C. 6362) and FAA Order 1053.1. It has been determined
that the final rule is not a major regulatory action under the
provisions of the EPCA.
List of Subjects
14 CFR Part 91
Aircraft, Aviation safety, Federal Aviation Administration,
Reporting and recordkeeping requirements.
14 CFR Part 121
Air carriers, Aircraft, Aviation Safety, Federal Aviation
Administration, Reporting and recordkeeping requirements, Safety,
Transportation.
14 CFR Part 125
Aircraft, Aviation safety, Federal Aviation Administration,
Reporting and recordkeeping requirements.
14 CFR Part 129
Air carriers, Aircraft, Aviation Safety, Federal Aviation
Administration, Reporting and recordkeeping requirements.
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends parts 91, 121, 125, and 129 of Title 14, Code of
Federal Regulations as follows:
PART 91--GENERAL OPERATING AND FLIGHT RULES
1. The authority citation for part 91 continues to read:
Authority: 49 U.S.C. 106(g), 40103, 40113, 40120, 44101, 44111,
44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 46306,
46315, 46316, 46502, 46504, 46506-46507, 47122, 47508, 47528-47531.
2. Add a new Sec. 91.410 to read as follows:
Sec. 91.410 Repair assessment for pressurized fuselages.
No person may operate an Airbus Model A300 (excluding the -600
series), British Aerospace Model BAC 1-11, Boeing Model, 707, 720, 727,
737 or 747, McDonnell Douglas Model DC-8, DC-9/MD-80 or DC-10, Fokker
Model F28, or Lockheed Model L-1011 airplane beyond applicable flight
cycle implementation time specified below, or May 25, 2001, whichever
occurs later, unless repair assessment guidelines applicable to the
fuselage pressure boundary (fuselage skin, door skin, and bulkhead
webs) that have been approved by the FAA Aircraft Certification Office
(ACO), or office of the Transport Airplane Directorate, having
cognizance over the type certificate for the affected airplane are
incorporated within its inspection program:
(a) For the Airbus Model A300 (excluding the -600 series), the
flight cycle implementation time is:
(1) Model B2: 36,000 flights.
(2) Model B4-100 (including Model B4-2C): 30,000 flights above the
window line, and 36,000 flights below the window line.
(3) Model B4-200: 25,000 flights above the window line, and 34,000
flights below the window line.
(b) For all models of the British Aerospace BAC 1-11, the flight
cycle implementation time is 60,000 flights.
(c) For all models of the Boeing 707, the flight cycle
implementation time is 15,000 flights.
(d) For all models of the Boeing 720, the flight cycle
implementation time is 23,000 flights.
(e) For all models of the Boeing 727, the flight cycle
implementation time is 45,000 flights.
(f) For all models of the Boeing 737, the flight cycle
implementation time is 60,000 flights.
(g) For all models of the Boeing 747, the flight cycle
implementation time is 15,000 flights.
(h) For all models of the McDonnell Douglas DC-8, the flight cycle
implementation time is 30,000 flights.
(i) For all models of the McDonnell Douglas DC-9/MD-80, the flight
cycle implementation time is 60,000 flights.
(j) For all models of the McDonnell Douglas DC-10, the flight cycle
implementation time is 30,000 flights.
(k) For all models of the Lockheed L-1011, the flight cycle
implementation time is 27,000 flights.
(l) For the Fokker F-28 Mark 1000, 2000, 3000, and 4000, the flight
cycle implementation time is 27,000 flights.
PART 121--CERTIFICATION AND OPERATIONS: DOMESTIC, FLAG, AND
SUPPLEMENTAL AIR CARRIERS AND COMMERCIAL OPERATORS OF LARGE
AIRCRAFT
1. The authority citation for part 121 continues to read:
Authority: 49 U.S.C. 106(g), 40113, 40119, 44101, 44701-44702,
44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-44904,
44912, 46105.
2. Add a new Sec. 121.370 to read as follows:
Sec. 121.370 Repair assessment for pressurized fuselages.
No certificate holder may operate an Airbus Model A300 (excluding
the -600 series), British Aerospace Model BAC 1-11, Boeing Model 707,
720, 727, 737, or 747, McDonnel Douglas Model DC-8, DC-9/MD-80 or DC-
10, Fokker Model F28, or Lockheed Model L-1011 airplane beyond the
applicable flight cycle implementation time specified below, or May 25,
2001, whichever
[[Page 24126]]
occurs later, unless operations specifications have been issued to
reference repair assessment guidelines applicable to the fuselage
pressure boundary (fuselage skin, door skin, and bulkhead webs), and
those guidelines are incorporated in its maintenance program. The
repair assessment guidelines must be approved by the FAA Aircraft
Certification Office (ACO), or office of the Transport Airplane
Directorate, having cognizance over the type certificate for the
affected airplane.
(a) For the Airbus Model A300 (excluding the -600 series), the
flight cycle implementation time is:
(1) Model B2: 36,000 flights.
(2) Model B4-100 (including Model B4-2C): 30,000 flights above the
window line, and 36,000 flights below the window line.
(3) Model B4-200: 25,000 flights above the window line, and 34,000
flights below the window line.
(b) For all models of the British Aerospace BAC 1-11, the flight
cycle implementation time is 60,000 flights.
(c) For all models of the Boeing 707, the flight cycle
implementation time is 15,000 flights.
(d) For all models of the Boeing 720, the flight cycle
implementation time is 23,000 flights.
(e) For all models of the Boeing 727, the flight cycle
implementation time is 45,000 flights.
(f) For all models of the Boeing 737, the flight cycle
implementation time is 60,000 flights.
(g) For all models of the Boeing 747, the flight cycle
implementation time is 15,000 flights.
(h) For all models of the McDonnell Douglas DC-8, the flight cycle
implementation time is 30,000 flights.
(i) For all models of the McDonnell Douglas DC-9/MD-80, the flight
cycle implementation time is 60,000 flights.
(j) For all models of the McDonnell Douglas DC-10, the flight cycle
implementation time is 30,000 flights.
(k) For all models of the Lockheed L-1011, the flight cycle
implementation time is 27,000 flights.
(l) For the Fokker F-28 Mark 1000, 2000, 3000, and 4000, the flight
cycle implementation time is 60,000 flights.
PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF
6,000 POUNDS OR MORE
1. The authority citation for part 125 continues to read:
Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44710-
44711, 44713, 44716-44717, 44722.
2. Add a new Sec. 125.248 to read as follows:
Sec. 125.248 Repair assessment for pressurized fuselages.
No person may operate an Airbus Model A300 (exlcuding the -600
series), British Aerospace Model BAC 1-11, Boeing Model 707, 720, 727,
737 or 747, McDonnell Douglas Model DC-8, DC-9/MD-80 or DC-10, Fokker
Model F28, or Lockheed Model L-1011 beyond the applicable flight cycle
implementation time specified below, or May 25, 2001, whichever occurs
later, unless operations specifications have been issued to reference
repair assessment guidelines applicable to the fuselage pressure
boundary (fuselage skin, door skin, and bulkhead webs), and those
guidelines are incorporated in its maintenance program. The repair
assessment guidelines must be approved by the FAA Aircraft
Certification Office (ACO), or office of the Transport Airplane
Directorate, having cognizance over the type certificate for the
affected airplane.
(a) For the Airbus Model A300 (excluding the -600 series), the
flight cycle implementation time is:
(1) Model B2: 36,000 flights.
(2) Model B4-100 (including Model B4-2C): 30,000 flights above the
window line, and 36,000 flights below the window line.
(3) Model B4-200: 25,000 flights above the window line, and 34,000
flights below the window line.
(b) For all models of the British Aerospace BAC 1-11, the flight
cycle implementation time is 60,000 flights.
(c) For all models of the Boeing 707, the flight cycle
implementation time is 15,000 flights.
(d) For all models of the Boeing 720, the flight cycle
implementation time is 23,000 flights.
(e) For all models of the Boeing 727, the flight cycle
implementation time is 45,000 flights.
(f) For all models of the Boeing 737, the flight cycle
implementation time is 60,000 flights.
(g) For all models of the Boeing 747, the flight cycle
implementation time is 15,000 flights.
(h) For all models of the McDonnell Douglas DC-8, the flight cycle
implementation time is 30,000 flights.
(i) For all models of the McDonnell Douglas DC-9/MD-80, the flight
cycle implementation time is 60,000 flights.
(j) For all models of the McDonnell Douglas DC-10, the flight cycle
implementation time is 30,000 flights.
(k) For all models of the Lockheed L-1011, the flight cycle
implementation time is 27,000 flights.
(l) For the Fokker F-28 Mark, 1000, 2000, 3000, and 4000, the
flight cycle implementation time is 60,000 flights.
PART 129--OPERATIONS: FOREIGN AIR CARRIERS AND FOREIGN OPERATORS OF
U.S.--REGISTERED AIRCRAFT ENGAGED IN COMMON CARRIAGE
1. The authority citation for part 129 continues to read:
Authority: 49 U.S.C. 106(g), 40104-40105, 40113, 40119, 44701-
44702, 44712, 44716-44717, 44722, 44901-44904, 44906.
2. Add a new Sec. 129.32 to read as follows:
Sec. 129.32 Repair assessment for pressurized fuselages.
No foreign air carrier or foreign persons operating a U.S.
registered airplane may operate an Airbus Model A300 (excluding -600
series), British Aerospace Model BAC 1-11, Boeing Model 707, 720, 727,
737, or 747, McDonnell Douglas Model DC-8, DC-9/MD-80 or DC-10, Fokker
Model F28, or Lockheed Model L-1011 beyond the applicable flight cycle
implementation time specified below, or May 25, 2001, whichever occurs
later, unless operations specifications have been issued to reference
repair assessment guidelines applicable to the fuselage pressure
boundary (fuselage skin, door skin, and bulkhead webs), and those
guidelines are incorporated in its maintenance program. The repair
assessment guidelines must be approved by the FAA Aircraft
Certification Office (ACO), or office of the Transport Airplane
Directorate, having cognizance over the type certificate for the
affected airplane.
(a) For the Airbus Model A300 (excluding the -600 series), the
flight cycle implementation time is:
(1) Model B2: 36,000 flights.
(2) Model B4-100 (including Model B4-2C): 30,000 flights above the
window line, and 36,000 flights below the window line.
(3) Model B4-200: 25,500 flights above the window line, and 34,000
flights below the window line.
(b) For all models of the British Aerospace BAC 1-11, the flight
cycle implementation time is 60,000 flights.
(c) For all models of the Boeing 707, the flight cycle
implementation time is 15,000 flights.
(d) For all models of the Boeing 720, the flight cycle
implementation time is 23,000 flights.
(e) For all models of the Boeing 727, the flight cycle
implementation time is 45,000 flights.
[[Page 24127]]
(f) For all models of the Boeing 737, the flight cycle
implementation time is 60,00 flights.
(g) For all models of the Boeing 747, the flight cycle
implementation time is 15,000 flights.
(h) For all models of the McDonnell Douglas DC-8, the flight cycle
implementation time is 30,000 flights.
(i) For all models of the McDonnell Douglas DC-9/MD-80, the flight
cycle implementation time is 60,000 flights.
(j) For all models of the McDonnell Douglas DC-10, the flight cycle
implementation time is 30,000 flights.
(k) For all models of the Lockheed L-1011, the flight cycle
implementation time is 27,000 flights.
(l) For the Fokker F-28 Mark 1000, 2000, 3000, and 4000, the flight
cycle implementation time is 60,00 flights.
Issued in Washington, DC, on April 19, 2000.
Jane F. Garvey,
Administrator of Federal Aviation Administration (FAA).
[FR Doc. 00-10220 Filed 4-24-00; 8:45 am]
BILLING CODE 4910-13-M