Airworthiness directives: Mitsubishi,
[Federal Register: July 9, 1998 (Volume 63, Number 131)]
[Proposed Rules]
[Page 37080-37082]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09jy98-16]
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).
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
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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 filedin 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
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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
-
The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
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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. 98-18156Filed7-8-98; 8:45 am]
BILLING CODE 4910-13-U
