[Federal Register Volume 63, Number 131 (Thursday, July 9, 1998)]
[Proposed Rules]
[Pages 37080-37082]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-18156]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-92-AD]
RIN 2120-AA64


Airworthiness Directives; Mitsubishi Model YS-11 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 all Mitsubishi Model YS-11 series 
airplanes. This proposal would require repetitive inspections to detect 
fatigue cracking in the manhole doublers of the lower wing panels; and 
repair, if necessary. This proposal also would require eventual 
modification of screw holes in the manhole doublers of the lower wing 
panels. This proposal is prompted by issuance of mandatory continuing 
airworthiness information by a foreign civil airworthiness authority. 
The actions specified by the proposed AD are intended to detect and 
correct fatigue cracking in the manhole doublers of the lower wing 
panels, which could result in failure of the wing structure.

DATES: Comments must be received by August 10, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-92-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, Transport Airplane Directorate, 
Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California.

FOR FURTHER INFORMATION CONTACT: William Roberts, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5228; fax (562) 
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

[[Page 37081]]

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 97-NM-92-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-114, Attention: Rules 
Docket No. 97-NM-92-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Japan Civil Aviation Bureau (JCAB), which is the airworthiness 
authority for Japan, notified the FAA that an unsafe condition may 
exist on all Mitsubishi Model YS-11 series airplanes. The JCAB advises 
that, during fatigue testing performed by the manufacturer, fatigue 
cracking was detected in the manhole doublers of a lower wing panel 
after 52,600 total flight cycles. The cracking has been attributed to 
stress concentrations caused by the manhole cutout and the screw holes. 
Cracks propagated quickly and also developed in the outer panel and 
stringer. Such fatigue cracking, if not detected and corrected, could 
progress to the wing skins and result in failure of the wing structure.

Explanation of Relevant Service Information

    Mitsubishi has issued Nihon Aeroplane Manufacturing Company (NAMC) 
YS-11 Service Bulletin 57-77, Revision 2, dated September 14, 1994, 
which describes procedures for repetitive visual inspections to detect 
fatigue cracking in the manhole doublers of the lower wing panels; 
repair, if necessary; and modification of screw holes in the manhole 
doublers of the lower wing panels. The modification involves a 
fluorescent penetrant or high-frequency eddy current inspection to 
detect cracking in the manhole doublers and screw holes, cold working 
(cold expansion) of the screw holes, and follow-on actions to prevent 
corrosion. (These follow-on actions include applying primer, 
anticorrosive, and sealant.) Accomplishment of the actions specified in 
the service bulletin is intended to adequately address the identified 
unsafe condition.
    The JCAB classified this service bulletin as recommended and issued 
Japanese airworthiness directive TCD-3795-2-96, dated December 13, 
1996, in order to assure the continued airworthiness of these airplanes 
in Japan.
    Mitsubishi also has issued NAMC YS-11 Supplemental Inspection 
Document (SID) Publication Number YS-MR-201, dated November 11, 1994. 
Inspection Item 57-00-03 of the SID (hereinafter referred to as ``the 
SID item'') describes procedures for repetitive visual inspections to 
detect fatigue cracking in the manhole doublers of the lower wing 
panels. These inspections essentially are equivalent to the repetitive 
visual inspections that would be required by this proposed AD. The JCAB 
approved the SID; however, the FAA has not been informed of the 
issuance of a Japanese airworthiness directive that would require 
accomplishment of the SID program for these airplanes in Japan.

FAA's Conclusions

    This airplane model is manufactured in Japan and is type 
certificated for operation in the United States under the provisions of 
section 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.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would require accomplishment of 
the actions specified in the service bulletin described previously, 
except as discussed below.

Differences Between Proposed Rule, Service Information, and 
Japanese Airworthiness Directive

    Operators should note that the SID item, described previously, 
specifies accomplishment of certain inspections that are equivalent to 
those that would be required by this proposed AD. However, because the 
inspections described in the SID have not been mandated previously by 
the FAA, and because failure to detect fatigue cracking in this area 
could result in the unsafe condition described previously, the FAA has 
determined that it is necessary to require accomplishment of these 
inspections, as well as modification of the affected area, via this 
proposed AD, in order to ensure the continued operational safety of 
these airplanes.
    Operators also should note that the service bulletin and the 
Japanese airworthiness directive, described previously, specify that 
accomplishment of the modification eliminates the need for the 
repetitive inspections described in the service bulletin. However, the 
SID item provides for continued inspections following accomplishment of 
the modification. Therefore, this proposed AD requires repetitive 
inspections after accomplishment of the modification proposed by this 
AD.
    Operators also should note that, although the service bulletin and 
the Japanese airworthiness directive specify accomplishment of the 
initial inspection prior to the accumulation of 60,000 total flight 
cycles, with a repetitive interval of 2,000 flight cycles, the SID item 
provides for an initial inspection prior to the accumulation of 45,000 
total flight cycles and a repetitive inspection interval of 8,000 
flight cycles. Following accomplishment of the modification described 
in the service bulletin, the SID item specifies that the repetitive 
interval is reduced to 6,000 flight cycles. In light of the compliance 
times recommended in the SID item, the FAA finds that the initial 
inspection must be accomplished prior to the accumulation of 45,000 
total flight cycles. However, the FAA has determined that an inspection 
interval of 6,000 flight cycles is appropriate, both before and after 
accomplishment of the modification specified in the service bulletin.
    Additionally, operators should note that the Japanese airworthiness 
directive specifies that modification of the screw holes in the manhole 
doublers of the lower wing panels be accomplished prior to the 
accumulation of 60,000 total flight cycles, or before December 13, 2000 
(four years after the effective date of the Japanese airworthiness 
directive), whichever occurs later. In developing

[[Page 37082]]

an appropriate compliance time for this proposed AD, the FAA considered 
not only the safety implications and the JCAB's recommendations, but 
also the manufacturer's recommendations. The manufacturer recommended 
accomplishment of the modification prior to the accumulation of 60,000 
total flight cycles, or January 8, 1997 (four years after the issuance 
of the original service bulletin). The FAA also considered the fact 
that the referenced version of the service bulletin (which contains the 
procedures for accomplishing the required modification) has been 
available to all operators of Mitsubishi YS-11 series airplanes since 
September 1994. In light of all of these factors, the FAA finds that 
the modification must be accomplished prior to the accumulation of 
60,000 total flight cycles, which represents an appropriate interval of 
time allowable for affected airplanes to continue to operate without 
compromising safety.

Cost Impact

    The FAA estimates that 25 airplanes of U.S. registry would be 
affected by this proposed AD.
    It would take approximately 30 work hours per airplane to 
accomplish the proposed inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the inspection 
proposed by this AD on U.S. operators is estimated to be $45,000, or 
$1,800 per airplane, per inspection cycle.
    It would take approximately 40 work hours per airplane to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$60,000, or $2,400 per airplane.
    The cost impact figures discussed above are 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.

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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Mitsubishi Heavy Industries, Ltd.: Docket 97-NM-92-AD.

    Applicability: All Model YS-11 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 request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracking in the manhole doublers 
of the lower wing panels, which could result in failure of the wing 
structure, accomplish the following:
    (a) Perform a visual inspection to detect cracking in the 
manhole doublers and around the screw holes of the lower wing 
panels, in accordance with Mitsubishi Nihon Aeroplane Manufacturing 
Company (NAMC) Service Bulletin 57-77, Revision 2, dated September 
14, 1994, at the time specified in either paragraph (a)(1) or (a)(2) 
of this AD, as applicable. Repeat the inspection thereafter at 
intervals not to exceed 6,000 flight cycles.
    (1) For airplanes that have accumulated fewer than 45,000 total 
flight cycles as of the effective date of this AD: Prior to the 
accumulation of 45,000 total flight cycles, or within 1 year after 
the effective date of this AD, whichever occurs later, perform the 
initial inspection.
    (2) For airplanes that have accumulated 45,000 or more total 
flight cycles as of the effective date of this AD: Within 2,000 
flight cycles or 1 year after the effective date of this AD, 
whichever occurs first, perform the initial inspection.
    (b) Modify the screw holes in the manhole doublers of the lower 
wing panels, in accordance with Mitsubishi NAMC Service Bulletin 57-
77, Revision 2, dated September 14, 1994, at the applicable time 
specified in either paragraph (b)(1) or (b)(2) of this AD. 
Thereafter, if any cracking is found, prior to further flight, 
repair the cracking in accordance with the service bulletin.

    Note 2: Accomplishment of the modification specified in 
paragraph (b) does not constitute terminating action for the 
repetitive inspections of paragraph (a).

    (1) If no cracking is found, prior to the accumulation of 60,000 
total flight cycles, or within 1 year after the effective date of 
this AD, whichever occurs later, accomplish the modification in 
accordance with the service bulletin.
    (2) If any cracking is found, prior to further flight, repair 
the cracking and accomplish the modification, in accordance with the 
service bulletin.
    (c) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Los Angeles ACO.
    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (d) Special flight permits may be issued in accordance with 
sections 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.

    Note 4: The subject of this AD is addressed in Japanese 
airworthiness directive TCD-3795-2-96, dated December 13, 1996.

    Issued in Renton, Washington, on July 1, 1998.
Stewart R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-18156 Filed 7-8-98; 8:45 am]
BILLING CODE 4910-13-U