[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