[Federal Register Volume 60, Number 75 (Wednesday, April 19, 1995)]
[Proposed Rules]
[Pages 19545-19549]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-9352]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-167-AD]
Airworthiness Directives; Mitsubishi Model YS-11 and -11A Series
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to Mitsubishi Model YS-11 and -11A
series airplanes. This proposal would require the implementation of a
corrosion prevention and control program. This proposal is prompted by
incidents involving corrosion and fatigue cracking in transport
category airplanes that are approaching or have exceeded their economic
design goal; these incidents have jeopardized the airworthiness of the
affected airplanes. The actions specified by the proposed AD are
intended to prevent degradation of the structural capabilities of the
affected airplanes due to problems associated with corrosion.
DATES: Comments must be received by May 25, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-167-AD, 1601 Lind Avenue SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays. -
The service information referenced in the proposed rule may be
obtained from Nihon Aeroplane Manufacturing, Toranomon Daiichi,
Kotohire-Cho, Shiba, Minato-Ku, Tokyo, Japan. This information may be
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue
SW., Renton, Washington; or at the FAA, Los Angeles Aircraft
Certification Office, Transport Airplane Directorate, 3960 Paramount
Boulevard, Lakewood, California.
FOR FURTHER INFORMATION CONTACT: William Roberts, Aerospace Engineer,
Airframe Branch, ANM-120L, Los Angeles Aircraft Certification Office,
FAA, Transport Airplane Directorate, 3960 Paramount Boulevard,
Lakewood, California 90712-4137; telephone (310) 627-5228; fax (310)
627-5210.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-NM-167-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 94-NM-167-AD, 1601 Lind Avenue SW., Renton, Washington
98055-4056.
Discussion
In April 1988, a transport category airplane managed to land after
tiny cracks in rivet holes in the upper fuselage linked together,
causing structural failure and explosive decompression. An 18-foot
section ripped from the fuselage. This accident focused greater
attention on the problem of aging aircraft.
In June 1988, the FAA sponsored an international conference on
aging airplane issues, which was attended by representatives of the
aviation industry from around the world. It became obvious that,
because of the tremendous increase in air travel, the relatively slow
pace of new airplane production, and the apparent economic feasibility
of operating older technology airplanes rather than retiring them,
increased attention needed to be focused on the aging fleets and
maintaining their continued operational safety.
In concert with the objectives that arose from this conference, the
``YS-11 Structures Working Group (SWG),'' was formed in 1990. This
group was comprised of representatives of several Japanese airlines and
overhaul facilities; Mitsubishi Heavy Industries (MHI), the airframe
manufacturer; and the Japan Civil Aviation Bureau (JCAB), which is the
airworthiness authority for Japan. It undertook the task of identifying
and [[Page 19546]] implementing procedures to ensure the continuing
structural airworthiness of Model YS-11 fleet.
As a result of this group's effort, a baseline program was
developed for controlling corrosion problems that may jeopardize the
continued airworthiness of the Model YS-11 fleet. The program is
contained in MHI Publication No. YS-MR-301, ``YS-11 Corrosion Control
Program,'' dated November 1, 1993 (hereafter referred to as ``the
Document'').
The JCAB has classified the Document as mandatory, and has issued
Japanese Airworthiness Directive TCF-50-001-1E-1, KU-KI-1532, TCD-3954-
93, dated December 27, 1993, addressing this subject.
Section 1.2 of the Document describes the basic requirements of the
corrosion control program (CCP).
Section 1.3 of the Document defines three levels of corrosion:
Level 1 corrosion is that which does not exceed certain limits; Level 2
corrosion is that which exceeds those limits; and Level 3 corrosion is
significant corrosion which is potentially an urgent airworthiness
concern.
Section 2 of the Document describes the general guidelines for
developing and implementing a corrosion prevention and control program.
These guidelines address such things as the scope and priority of the
baseline program; the relationship between an operator's maintenance
program and the CCP; intervals for accomplishment of the basic tasks
for corrosion prevention; selection of corrosion preventive compound;
and how the program relates to newly-acquired, leased, and transferred
airplanes. This section also provides for periodic review and update of
the data contained in the Document.
It should be noted that this section indicates that, since more
than 20 years have passed since most Model YS-11 airplanes were last
manufactured, implementation of the Baseline Program is necessary for
all airplanes. In light of this, the program described in the Document
does not specify any particular ``implementation age'' for initiating
the program on a particular airplane. Instead, it emphasizes developing
and adopting a program, then accomplishing the specific actions on each
airplane in an operator's fleet, on a phased-in basis.
Section 3 of the Document establishes the procedures for reporting
the results of the inspections conducted under the program. It
describes the specific system for reporting of findings when various
levels of corrosion are determined to exist.
Section 4 of the Document lays out the recommended baseline
program. This section describes the ``basic task'' to be accomplished
in each defined airplane area (``zone'') as part of the baseline
program, the specific airplane areas that are subject to the program,
and the intervals for inspecting areas and applying corrosion
preventive compound. A ``basic task'' includes visual inspections of
all primary and secondary structures, and may also include detailed
visual and non-destructive inspections (NDI). Any corrosion or other
damage found as a result of these inspections must be repaired.
This airplane model is manufactured in Japan and is type
certificated for operation in the United States under the provisions of
Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the
applicable bilateral airworthiness agreement. Pursuant to this
bilateral airworthiness agreement, the JCAB has kept the FAA informed
of the situation described above. The FAA has examined the findings of
the JCAB, reviewed all available information, and determined that AD
action is necessary for products of this type design that are
certificated for operation in the United States.
Since corrosion is likely to exist or develop on airplanes of this
type design, an AD is proposed which would require adoption of a
corrosion prevention and control program that is equivalent to or
better than the program specified in the Document previously described.
Operators would be permitted to accomplish this either by performing
the specific basic tasks described in the Document (the ``task-by-task
method), or by revising their FAA-approved maintenance program to
include such a program.
Paragraph (a) of the proposal sets forth the proposed compliance
time for the implementation of the schedule for accomplishing the basic
task for each affected aircraft area. The basic task would be required
to be repeated at a time interval not to exceed the repeat interval for
that area, as detailed in the Document.
Operators should note that the proposal does not contain a
paragraph specifically to address repair actions. The FAA considers
that any repairs would be carried out necessarily as a part of each
basic task, as it is defined in the Document. As discussed previously,
a ``basic task'' is defined in the Document as including not only the
pertinent inspection, but any necessary repairs, application of
corrosion inhibitors, and other follow-on procedures, as well.
Paragraph (a) contains a note to reference the portion of the Document
that defines a basic task, and to emphasize the importance of these
corrective actions.
Paragraph (b) of the proposal provides for an optional method of
complying with the rule. In lieu of performing the task-by-task
requirements proposed in paragraph (a), operators may revise their FAA-
approved maintenance/inspection programs to include the corrosion
prevention and control program defined in the Document or an equivalent
program approved by the FAA.
Paragraph (b) also would require that, subsequent to the
accomplishment of the initial basic task, any extensions of repeat
intervals specified in the Document must be approved by the FAA.
Any operator electing to comply with proposed paragraph (b) would
be permitted to use an alternative recordkeeping method to that
otherwise required by Federal Aviation Regulations (FAR) Sec. 91.417 or
Sec. 121.380, provided it is approved by the FAA and is included in a
revision to the FAA-approved maintenance/inspection program. In
response to questions raised previously concerning recordkeeping and
record retention requirements as they relate to the programmatic
approach proposed in this AD action and other similar proposals that
have been issued applicable to other airplane models, the FAA offers
the following: -
Sections 91.417(a)(2)(v) and 121.380(a)(2)(v) of the FAR require
that a record be made of the current status of applicable AD's. With
regard to proposed paragraph (b), such a record would be required to be
made when the maintenance/inspection program is revised to incorporate
the program specified in the Document; at that time, paragraph (b) of
the AD would be fully complied with. Regarding paragraphs (d) through
(g) of this proposal, those paragraphs would impose separate
requirements; therefore, except as discussed below, separate entries
would have to be made to reflect compliance with each of those
paragraphs.
Section 121.380(a)(2)(iv) of the FAR concerns recording ``the
identification of the current inspection status of the aircraft.''
Section 91.417(a)(2)(iv) contains a similar requirement. Because
proposed paragraph (b) would require operators to revise their
maintenance/inspection program to include the program specified in the
Document, each operator's program would require a record of each
inspection to be performed. By recording the current inspection status
of each airplane, and by maintaining a cross-reference system between
these records and the [[Page 19547]] maintenance/inspection program
revision, it will be possible to determine the current status of each
basic task on each airplane. Once this cross-reference system has been
established (normally within a year after the effective date of the
AD), this recording provision of Sections 91 and 121 requires no
additional recording beyond what would otherwise be required normally.
Section 121.380(a)(1) concerns ``records necessary to show that all
requirements for the issuance of an airworthiness release under Section
121.709 have been met.'' Section 91.417(a)(1) contains a similar
requirement. These are also referred to as ``dirty fingerprint
records.'' This provision of Sections 91 and 121 requires most of the
recording that would result from this proposed AD. Each time a basic
task is performed, the operator would be required to make a ``dirty
fingerprint'' record of the task, identifying what actions were
accomplished. It should be noted, however, that these records are not
different from the records made for any other actions taken under the
operator's maintenance/inspection program.
In addition to the record making requirements, discussed above,
Sections 91 and 121 of the FAR impose requirements for record
retention:
Section 121.380(b)(1) and Section 91.417(b)(1) require that the
``dirty fingerprint'' records be retained until the work is repeated or
superseded by other work, or for one year after the work is performed.
Therefore, most of the records resulting from this proposed AD would
not have to be retained indefinitely. However, such retention might
facilitate subsequent transfers, or substantiate requests for
repetitive interval escalations, and therefore, may be in the
operator's interest.
Section 121.380(b)(2) requires that the records specified in
paragraph 121.380(a)(2) [current status of AD's and current inspection
status] be retained and transferred with the airplane at the time it is
sold. Section 91.417(b)(2) contains a similar requirement.
These recording requirements are not considered to be unduly
burdensome and are considered the minimum necessary to enable the
cognizant FAA Maintenance Inspector to perform proper surveillance and
to ensure that the objectives of the proposed rule are being fulfilled.
Due to numerous concerns expressed previously by operators
regarding the recordkeeping obligations imposed by Section 121.380 with
regard to similar rulemaking on corrosion prevention and control
programs, the FAA has included in this proposal certain provisions for
alternative recordkeeping methods. Proposed paragraph (b)(1) would
provide for the development and implementation of such alternative
methods, which must be approved by the FAA. For example, operators may
choose to submit proposals to record compliance with paragraphs (d)
through (g) of the AD by a means other than they normally use to record
AD status. [The FAA has developed guidance material that will contain
information to be considered by FAA Principal Maintenance Inspectors
(PMI) when reviewing proposals for alternative recordkeeping methods.]
Paragraph (c) of the proposal provides for increasing a repeat
interval by up to 10% in order to accommodate unanticipated scheduling
requirements. Operators would be required to inform the FAA within 30
days of such increases.
Paragraph (d)(1) of the proposal sets forth the reporting actions
that are necessary to be accomplished when Level 3 corrosion is
determined to exist. Within 7 days after such a determination is made,
an operator would be required to accomplish one of the following
actions:
1. Submit a report of the determination to the FAA and complete the
basic task in the affected area on the remainder of the Model YS-11/-
11A series airplanes in the operator's fleet; or
2. Submit a proposed schedule, for approval by the FAA, for
performing the basic tasks in the affected area on the remainder of the
operator's Model YS-11/-11A series fleet; or
3. Submit data substantiating that the Level 3 corrosion was an
isolated occurrence.
Once the FAA has received such a report, it may, in conjunction
with normal surveillance activities, request additional information
regarding the results of the basic tasks performed on the remainder of
the operator's Model YS-11/-11A series fleet.
Paragraph (d)(2) of the proposal specifies that the FAA may impose
schedules different from what an operator has proposed under paragraph
(d)(1), if it is found that changes are necessary to ensure that any
other Level 3 corrosion in the operator's Model PYS-11 series fleet is
detected in a timely manner.
Paragraph (d)(3) of the proposal would require that, within the
time schedule approved by the FAA, the operator must accomplish the
basic tasks in the affected areas on the remaining airplanes in its
Model YS-11/-11A series fleet to ensure that any other Level 3
corrosion is detected and repaired.
Paragraph (e) would require that, upon finding corrosion exceeding
Level 1 during a repetitive inspection, an operator must adjust its
program to ensure that future corrosion findings are limited to Level 1
or better. Where corrective action is necessary to reduce corrosion to
Level 1 or better, an operator must submit a proposal for corrective
action for the FAA's approval within 60 days after the determination of
corrosion is made. That action, approved by the FAA, must then be
implemented to reduce future findings of corrosion in that area to
Level 1 or better.
With regard to paragraph (e), it should be noted that if corrosion
is found and it is not considered representative of the operator's
fleet, no further corrective action may be necessary, since a means to
reduce any corrosion to Level 1 or better will have already been
implemented in the operator's program in accordance with proposed
paragraph (a) or (b). For example, if a finding of corrosion is
attributable to a particular spill of mercury or other unique event, or
if corrosion is found on an airplane recently acquired from another
operator, the means specified in the existing program may be adequate
for controlling corrosion in the remainder of the operator's fleet.
Similarly, if an operator has already implemented means to reduce
corrosion in an airplane area based on previous findings, no additional
corrective action may be necessary. In reviewing the reports submitted
in accordance with the AD, the FAA will monitor the effectiveness of
the corrective action to reduce corrosion. If the FAA determines that
an operator has failed to implement adequate means to reduce corrosion
to Level 1 or better, appropriate action will be taken to ensure
compliance with this paragraph.
Paragraph (f) of the proposal concerns adding airplanes to an
operator's fleet, and the procedures that must be followed with regard
to corrosion prevention and control. This paragraph differentiates
between procedures applicable to added airplanes that previously were
maintained in accordance with this AD and those that were not so
maintained. For airplanes that previously have been maintained in
accordance with the proposed requirements of this AD action, the first
basic task in each aircraft area to be performed by the new operator
would be required to be performed in accordance with either the
previous operator's or the new operator's inspection schedule,
whichever would result in the earlier accomplishment date for that
task. For airplanes that [[Page 19548]] have not been maintained in
accordance with the proposed requirements of this AD action, the first
basic task in each aircraft area to be performed by the new operator
would be required to be performed before the airplane is placed in
service, or in accordance with a schedule approved by the FAA.
With regard to the requirements of paragraph (f), the FAA considers
it essential that operators ensure that transferred airplanes are
inspected in accordance with the baseline corrosion prevention and
control program on the same basis as if there were continuity in
ownership. Scheduling of the inspections for each airplane must not be
delayed or postponed due to a transfer of ownership. The proposed rule
would require that the specified procedures be accomplished before any
operator places into service any airplane subject to the requirements
of the proposed AD.
Paragraph (g) of the proposal would require that reports of Level 2
and Level 3 corrosion be submitted to Mitsubishi within certain time
periods after such corrosion is detected. A note has been included in
this paragraph indicating that reporting to the FAA of any Level 2 or
Level 3 corrosion found as a result of any opportunity inspections is
highly desirable. Operators are not relieved, however, from reporting
corrosion findings as required by FAR Sec. 121.703.
Cost Impact
The FAA estimates that 39 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 8 work
hours per basic task to accomplish the 30 basic tasks called out in the
Document; this represents a total average of 240 work hours (this
figure includes not only inspection time, but access and closure time
as well).
The average labor rate is $60 per work hour. Based on these
figures, the total cost impact of the proposed AD on U.S. operators for
the 4-year average inspection cycle is estimated to be $561,600, or
$14,400 per airplane.
The total cost impact figure discussed above is based on
assumptions that no operator has yet accomplished any of the proposed
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address specific unsafe conditions, they
appear to impose costs that would not otherwise be borne by operators.
However, because of the general obligation of operators to maintain
aircraft in an airworthy condition, this appearance is deceptive.
Attributing those costs solely to the issuance of this AD is
unrealistic because, in the interest of maintaining safe aircraft,
prudent operators would accomplish the required actions even if they
were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this
proposed AD. As a matter of law, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that it complies with all applicable airworthiness
requirements. In adopting and maintaining those requirements, the FAA
has already made the determination that they establish a level of
safety that is cost-beneficial. When the FAA, as in this proposed AD,
makes a finding of an unsafe condition, this means that the original
cost-beneficial level of safety is no longer being achieved and that
the proposed actions are necessary to restore that level of safety.
Because this level of safety has already been determined to be cost-
beneficial, a full cost-benefit analysis for this proposed AD would be
redundant and unnecessary.
Regulatory Impact
The regulations proposed herein would not have substantial direct
effects 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, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part 39 of the Federal Aviation Regulations (14 CFR part 39) as
follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Mitsubishi Heavy Industries, Ltd.: Docket 94-NM-167-AD.
Applicability: All Model YS-11 and -11A series airplanes,
certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must use the authority
provided in paragraph (h) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
Note 2: This AD references MHI Publication No. YS-MR-301, ``YS-
11 Corrosion Control Program,'' dated November 1, 1993 (hereafter
referred to as ``the Document''), for basic tasks, definitions of
corrosion levels, compliance times, and reporting requirements. In
addition, this AD specifies inspection and reporting requirements
beyond those included in the Document. Where there are differences
between the AD and the Document, the AD prevails.
Note 3: As used throughout this AD, the term ``the FAA'' is
defined differently for different operators, as follows: For those
operators complying with paragraph (a) of this AD, ``the FAA'' is
defined as ``the Manager of the Los Angeles Aircraft Certification
Office (ACO).'' For those operators operating under Federal Aviation
[[Page 19549]] Regulation (FAR) Part 121 or 129, and complying with
paragraph (b) of this AD, ``the FAA'' is defined as ``the cognizant
Principal Maintenance Inspector (PMI).'' For those operators
operating under FAR Part 91 or 125, and complying with paragraph (b)
of this AD, ``the FAA'' is defined as ``the cognizant Maintenance
Inspector at the appropriate FAA Flight Standards office.''
To preclude degradation of the structural capabilities of the
airplane due to the problems associated with corrosion, accomplish
the following:
(a) Except as provided in paragraph (b) of this AD, within a
date two years after the effective date of this AD, complete each of
the basic tasks specified in Section 4.3 of the Document in
accordance with the procedures specified in the Document and the
schedule specified in Figure 5 of the Document. Thereafter, repeat
each basic task at a time interval not to exceed the repeat interval
specified in Section 4 of the Document for that task.
Note 4: A ``basic task,'' as defined in Section 4 of the
Document, includes inspections; procedures for a corrective action,
including repairs, under identified circumstances; application of
sealants or corrosion inhibitors; and other follow-on actions.
Note 5: Basic tasks completed in accordance with the Document
before the effective date of this AD may be credited for compliance
with the initial basic task requirements of this paragraph.
Note 6: Where non-destructive inspection (NDI) methods are
employed, in accordance with Section 4 of the Document, the
standards and procedures used must be acceptable to the
Administrator in accordance with FAR Section 43.13.
(b) As an alternative to the requirements of paragraph (a) of
this AD: Within one year after the effective date of this AD, revise
the FAA-approved maintenance/inspection program to include the
corrosion control program specified in the Document; or to include
an equivalent program that is approved by the FAA.
(1) Any operator complying with paragraph (b) of this AD may use
an alternative recordkeeping method to that otherwise required by
FAR Sec. 91.417 or Sec. 121.380 for the actions required by this AD,
provided it is approved by the FAA and is included in a revision to
the FAA-approved maintenance/inspection program.
(2) Subsequent to the accomplishment of the initial basic task,
any extensions of repeat intervals specified in the Document must be
approved by the FAA.
(c) To accommodate unanticipated scheduling requirements, it is
acceptable for a repeat interval to be increased by up to 10%, but
not to exceed 6 months. The FAA must be informed, in writing, of any
such extension within 30 days after such adjustment of the schedule.
(d)(1) If, as a result of any inspection conducted in accordance
with paragraphs (a) or (b) of this AD, Level 3 corrosion is
determined to exist in any airplane area, accomplish either
paragraph (d)(1)(i) or (d)(1)(ii) within 7 days after such
determination:
(i) Submit a report of that determination to the FAA and
complete the basic task in the affected aircraft zones on all Model
YS-11/-11A series airplanes in the operator's fleet; or
(ii) Submit to the FAA for approval one of the following:
(A) A proposed schedule for performing the basic tasks in the
affected aircraft zones on the remaining Model YS-11/-11A series
airplanes in the operator's fleet, which is adequate to ensure that
any other Level 3 corrosion is detected in a timely manner, along
with substantiating data for that schedule; or
(B) Data substantiating that the Level 3 corrosion found is an
isolated occurrence.
Note 7: Notwithstanding the provisions of section 1.3 of the
Document, which would permit corrosion that otherwise meets the
definition of Level 3 corrosion (i.e., which is determined to be a
potentially urgent airworthiness concern requiring expeditious
action) to be treated as Level 1 if the operator finds that it ``can
be attributed to an event not typical of the operator's usage of
other airplanes in the same fleet,'' this paragraph requires that
data substantiating any such finding be submitted to the FAA for
approval.
(2) The FAA may impose schedules other than those proposed, upon
finding that such changes are necessary to ensure that any other
Level 3 corrosion is detected in a timely manner.
(3) Within the time schedule approved under paragraph (d)(1) or
(d)(2) of this AD, accomplish the basic tasks in the affected
aircraft zones of the remaining Model YS-11/-11A series airplanes in
the operator's fleet.
(e) If, as a result of any inspection after the initial
inspection conducted in accordance with paragraphs (a) or (b) of
this AD, it is determined that corrosion findings exceed Level 1 in
any area, within 60 days after such determination, implement a
means, approved by the FAA, to reduce future findings of corrosion
in that area to Level 1 or better.
(f) Before any operator places into service any airplane subject
to the requirements of this AD, a schedule for the accomplishment of
basic tasks required by this AD must be established in accordance
with paragraph (f)(1) or (f)(2) of this AD, as applicable:
(1) For airplanes previously maintained in accordance with this
AD, the first basic task in each aircraft zone to be performed by
the new operator must be accomplished in accordance with the
previous operator's schedule or with the new operator's schedule,
whichever would result in the earlier accomplishment date for that
task. After each basic task has been performed once, each subsequent
task must be performed in accordance with the new operator's
schedule.
(2) For airplanes that have not been previously maintained in
accordance with this AD, the first basic task for each aircraft zone
to be performed by the new operator must be accomplished prior to
further flight or in accordance with a schedule approved by the FAA.
(g) Reports of Level 2 and Level 3 corrosion must be submitted
at least every three months to Mitsubishi Heavy Industries, Ltd., in
accordance with Section 3 of the Document.
Note 8: Reporting of Level 2 and Level 3 corrosion found as a
result of any opportunity inspections is highly desirable.
(h) An alternative method of compliance or adjustment of the
compliance time, which provides an acceptable level of safety, may
be used when approved by the Manager, Los Angeles Aircraft
Certification Office (ACO), FAA, Transport Airplane Directorate.
Operators shall submit their requests through the cognizant
Maintenance Inspector at the appropriate FAA Flight Standards
office, who may concur or comment and then send it to the Manager,
Los Angeles ACO.
Note 9: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(i) Special flight permits may be issued in accordance with
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR
21.197 and 21.199) to operate the airplane to a location where the
requirements of this AD can be accomplished.
(j) Reports of inspection results required by this AD have been
approved by the Office of Management and Budget (OMB) under the
provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et
seq.) and have been assigned OMB Control Number 2120-0056.
Issued in Renton, Washington, on April 10, 1995.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-9352 Filed 4-18-95; 8:45 am]
BILLING CODE 4910-13-U