Airworthiness directives: Saab,
[Federal Register: February 18, 1999 (Volume 64, Number 32)]
[Proposed Rules]
[Page 8029-8031]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18fe99-23]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-220-AD]
RIN 2120-AA64
Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B 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 certain Saab Model SAAB SF340A and SAAB 340B series airplanes. This proposal would require repetitive inspections to detect cracking around certain fastener holes and adjacent areas of the front spar of the horizontal stabilizers; and corrective actions, if necessary. This proposal also would require cold working of certain fastener holes of the front spar of the horizontal stabilizers, and follow-on actions; and installation of new fasteners, which would constitute terminating action for the repetitive inspections proposed by this AD. 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 prevent failure of the front spar due to fatigue cracking around certain fastener holes of the front spar of the horizontal stabilizers, which could result in reduced structural integrity of the airplane.
DATES: Comments must be received by March 22, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-220-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 Saab Aircraft AB, SAAB Aircraft Product Support, S- 581.88, Linkoping, Sweden. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.
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 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 98-NM-220-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.
[[Page 8030]]
98-NM-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
The Luftfartsverket (LFV), which is the airworthiness authority for Sweden, notified the FAA that an unsafe condition may exist on certain Saab Model SAAB SF340A and SAAB 340B series airplanes. The LFV advises that, during full-scale fatigue testing on a test article, cracking was found in the front spar of the horizontal stabilizer at the intersection between the rear fuselage and the front upper spar cap. Further investigation revealed that the fatigue cracking may have originated at one of the fastener holes in the upper part of the web of the front spar. Such fatigue cracking, if not detected and corrected, could result in reduced structural integrity of the airplane.
Explanation of Relevant Service Information
The manufacturer has issued SAAB Service Bulletin 340-55-033, Revision 04, dated December 1, 1998, which describes procedures for repetitive detailed visual and eddy current inspections to detect cracking around certain fastener holes and adjacent areas of the front spar of the horizontal stabilizers.
The manufacturer also has issued SAAB Service Bulletin 340-55-034, dated October 16, 1998, which describes procedures for cold working of certain fastener holes of the front spar of the horizontal stabilizers, and follow-on actions. The follow-on actions involve performing eddy current inspections of specified areas to detect cracking of certain fastener holes before and after cold working and after oversizing any hole. The service bulletin also describes procedures for installation of new fasteners into certain holes of the front spar of the horizontal stabilizers. Accomplishment of these actions would eliminate the need for the repetitive inspections described in Saab Service Bulletin 340- 55-033.
Accomplishment of the actions specified in the Saab service bulletins is intended to adequately address the identified unsafe condition. The LFV classified these service bulletins as mandatory and issued Swedish airworthiness directives 1-110R2, dated December 7, 1998, and 1-133, dated October 20, 1998, in order to assure the continued airworthiness of these airplanes in Sweden.
FAA's Conclusions
These airplane models are manufactured in Sweden and are 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 LFV has kept the FAA informed of the situation described above. The FAA has examined the findings of the LFV, 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 bulletins described previously, except as discussed below.
Differences Between Proposed Rule and Service Information
Operators should note that, although the service bulletins specify that the manufacturer may be contacted for the disposition of certain cracking conditions around certain fastener holes of the front spar of the horizontal stabilizers, this AD would require repair of any fatigue cracking to be accomplished in accordance with a method approved by either the FAA, or the LFV (or its delegated agent). In light of the type of repair that would be required to address the identified unsafe condition, and in consonance with existing bilateral airworthiness agreements, the FAA has determined that, for this AD, a repair approved by either the FAA or the LFV is acceptable for compliance with this AD.
Cost Impact
The FAA estimates that 279 airplanes of U.S. registry would be affected by this proposed AD.
It would take approximately 4 work hours per airplane to perform the detailed visual 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 $66,960, or $240 per airplane, per inspection cycle.
It would take approximately 6 work hours per airplane to accomplish the proposed eddy current 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 $100,440, or $360 per airplane, per inspection cycle.
It would take approximately 42 work hours to accomplish the cold working of the fastener holes, at an average labor rate of $60 per work hour. Required parts would cost approximately $400 per airplane. Based on these figures, the cost impact of the cold work proposed by this AD on U.S. operators is estimated to be $814,680, or $2,920 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.
[[Page 8031]]
Sec. 39.13 [Amended]
-
Section 39.13 is amended by adding the following new airworthiness directive:
Saab Aircraft AB: Docket 98-NM-220-AD.
Applicability: Model SAAB SF340A series airplanes, manufacturer's serial numbers -004 through -159 inclusive; and SAAB 340B series airplanes, manufacturer's serial numbers -160 through - 439 inclusive; 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 (f) 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 prevent failure of the front spar due to fatigue cracking around certain fastener holes of the front spar of the horizontal stabilizers, which could result in reduced structural integrity of the airplane, accomplish the following:
(a) For SAAB SF340A series airplanes with manufacturer's serial numbers -004 through -159 inclusive: Perform inspections to detect cracking around certain fastener holes and adjacent areas of the front spar of the horizontal stabilizer, in accordance with Saab Service Bulletin 340-55-033, Revision 04, dated December 1, 1998, at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. Thereafter, repeat the eddy current inspection at intervals not to exceed 12,000 flight cycles until the requirements of paragraph (d) of this AD are accomplished.
(1) For airplanes that have accumulated less than 22,000 total flight cycles as of the effective date of this AD: Perform an eddy current inspection prior to the accumulation of 22,000 total flight cycles, or within 2,000 flight cycles after the effective date of this AD, whichever occurs later.
(2) For airplanes that have accumulated 22,000 or more total flight cycles and less than 30,000 total flight cycles as of the effective date of this AD: Accomplish the requirements of paragraphs (a)(2)(i) and (a)(2)(ii) of this AD.
(i) Perform a detailed visual inspection within 800 flight cycles after the effective date of this AD; and
(ii) Perform an eddy current inspection within 2,000 flight cycles after the effective date of this AD.
(3) For airplanes that have accumulated 30,000 or more total flight cycles as of the effective date of this AD: Accomplish the requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD.
(i) Perform a detailed visual inspection within 400 flight cycles after the effective date of this AD; and
(ii) Perform an eddy current inspection within 1,200 flight cycles after the effective date of this AD.
(b) For SAAB 340B series airplanes with manufacturer's serial numbers -160 through -439 inclusive: Perform inspections to detect cracking around certain fastener holes and adjacent areas of the front spar of the horizontal stabilizer, in accordance with Saab Service Bulletin 340-55-033, Revision 04, dated December 1, 1998, at the time specified in paragraph (b)(1), (b)(2), or (b)(3) of this AD, as applicable. Thereafter, repeat the eddy current inspection at intervals not to exceed 6,000 flight cycles until the requirements of paragraph (d) of this AD are accomplished.
(1) For airplanes that have accumulated less than 12,000 total flight cycles as of the effective date of this AD: Perform an eddy current inspection prior to the accumulation of 12,000 total flight cycles, or within 2,000 flight cycles after the effective date of this AD, whichever occurs later.
(2) For airplanes that have accumulated 12,000 or more total flight cycles and less than 16,000 total flight cycles as of the effective date of this AD: Accomplish the requirements of paragraphs (b)(2)(i) and (b)(2)(ii) of this AD.
(i) Perform a detailed visual inspection within 800 flight cycles after the effective date of this AD; and
(ii) Perform an eddy current inspection within 2,000 flight cycles after the effective date of this AD.
(3) For airplanes that have accumulated 16,000 or more total flight cycles as of the effective date of this AD: Accomplish the requirements of paragraphs (b)(3)(i) and (b)(3)(ii) of this AD.
(i) Perform a detailed visual inspection within 400 flight cycles after the effective date of this AD; and
(ii) Perform an eddy current inspection within 1,200 flight cycles after the effective date of this AD.
(c) If any cracking is detected during any inspection required by paragraph (a) or (b) of this AD, prior to further flight, either repair in accordance with a method approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, or the Luftfartsverket (LFV) (or its delegated agent); or accomplish the requirements of paragraph (d) of this AD.
Note 2: Inspections to detect cracking around certain fastener holes and adjacent areas of the front spar of the horizontal stabilizers that have been accomplished prior to the effective date of this AD in accordance with Saab Service Bulletin 340-55-033, Revision 03, dated January 22, 1998, are considered acceptable for compliance with the applicable action specified by this AD.
(d) For all airplanes: Except as provided by paragraph (e) of this AD, accomplish cold working of certain fastener holes of the front spar of the horizontal stabilizers, and follow-on actions; and install new fasteners; in accordance with Saab Service Bulletin 340- 55-034, dated October 16, 1998; at the time specified in paragraph (d)(1), (d)(2), or (d)(3) of this AD, as applicable. Accomplishment of this action constitutes terminating action for this AD.
(1) For all airplanes that have accumulated less than 26,000 total flight cycles as of the effective date of this AD: Within 10,000 flight cycles after the effective date of this AD.
(2) For all airplanes that have accumulated 26,000 or more total flight cycles and less than 30,000 total flight cycles as of the effective date of this AD: Within 6,000 flight cycles after the effective date of this AD.
(3) For all airplanes that have accumulated 30,000 or more total flight cycles as of the effective date of this AD: Within 3,000 flight cycles after the effective date of this AD.
(e) If any crack is detected during the accomplishment of paragraph (d) of this AD, and if the service bulletin listed in paragraph (d) of this AD specifies to contact the manufacturer for an appropriate corrective action: Prior to further flight, repair in accordance with a method approved by the Manager, International Branch, ANM-116, or the LFV (or its delegated agent).
(f) 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, International Branch, ANM-116. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.
Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.
(g) 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 Swedish airworthiness directives 1-110R2, dated December 7, 1998, and 1-133, dated October 20, 1998.
Issued in Renton, Washington, on February 11, 1999. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-4013Filed2-17-99; 8:45 am]
BILLING CODE 4910-13-U
