[Federal Register Volume 62, Number 9 (Tuesday, January 14, 1997)] [Proposed Rules] [Pages 1866-1868] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-883] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 96-NM-185-AD] RIN 2120-AA64 Airworthiness Directives; Fokker Model F28 Mark 0100 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 Fokker Model F28 Mark 0100 series airplanes. This proposal would require repetitive inspections of certain flanges and finger strips at rib 5.0 of the vertical stabilizer to detect fatigue cracking, and repairs, if necessary. It also would require modifications that would strengthen the torsion box at rib 5.0 and prevent fatigue cracking; one of these modifications would be terminating action for the repetitive inspections. This proposal is prompted by reports indicating that, during full-scale fatigue testing, cracking has been found on the vertical stabilizer of the test article. The actions specified by the proposed AD are intended to detect and prevent fatigue cracking in the subject area, which, if not corrected, could reduce the structural integrity of the vertical stabilizer. DATES: Comments must be received by February 24, 1997. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-185-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 Fokker Services B.V., Technical Support Department, P.O. Box 75047, 1117 ZN Schiphol Airport, The Netherlands. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: Tim Dulin, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2141; fax (206) 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 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 96-NM-185-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. 96-NM-185-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, has notified the FAA that an unsafe condition may exist on certain Fokker Model F28 Mark 0100 series airplanes. The RLD advises that it has received reports indicating that cracks have been found on the vertical stabilizer during the manufacturer's full-scale fatigue tests on the Fokker Model F28 Mark 0100 test article. These fatigue cracks were detected at the bolt holes of the right-hand flange of the torsion box, and in the finger strip on the left-hand flange at rib 5.0 of the vertical stabilizer. The RLD also advises that it has received reports indicating that subsequent full-scale fatigue tests have detected additional cracks in rib 5.0 of the vertical stabilizer after a stiffener had been added to the torsion box in accordance with Fokker Service Bulletin SBF100-55- 018. Although this modification was performed to strengthen this area against fatigue cracking, investigation has shown that the stiffener produces a too-rapid change in the structural strength of the torsion box, which may lead to fatigue cracking in an adjacent area. Fatigue cracking in the subject area, if not prevented, could reduce structural integrity of the vertical stabilizer. Explanation of Relevant Service Information Fokker has issued Service Bulletin SBF100-55-019, Revision 1, dated May 19, 1993, which describes procedures for conducting repetitive eddy current inspections of the flanges and finger strips at rib 5.0 of the vertical stabilizers to detect fatigue cracking, and repair, if necessary. Fokker also has issued Service Bulletin SBF100-55-018, Revision 1, dated December 27, 1993, which describes procedures for modifying the torsion box at rib 5.0 of the vertical stabilizer by installing stiffening to the rib web and flanges for added strength. This service bulletin also describes procedures for a pre-modification eddy current inspection of the vertical stabilizer to detect cracking, and repair, if necessary, in accordance with Fokker Service Bulletin SBF100-55-019. Accomplishment of this modification eliminates the need for repetitive inspections to detect fatigue cracking. Additionally, Fokker has issued Service Bulletin SBF100-55-023, dated January 3, 1995, which describes procedures for another modification to strengthen rib 5.0 of the vertical stabilizer. This modification, which entails the cold expansion of holes in the torsion box at rib 5.0, is intended to prevent additional fatigue cracking that could be caused by the earlier installation of the torsion box stiffener. The RLD classified these service bulletins as mandatory and issued Netherlands airworthiness directives (BLA) 93-069 (A), dated June 1, 1993, and BLA 1995-017 (A), dated February 28, 1995, in order to assure the continued airworthiness of these airplanes in the Netherlands. [[Page 1867]] FAA's Conclusions This airplane model is manufactured in the Netherlands 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 RLD has kept the FAA informed of the situation described above. The FAA has examined the findings of the RLD, 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 repetitive eddy current inspections to detect fatigue cracking of the left-hand and right-hand flanges and finger strips at rib 5.0 of the vertical stabilizer, and repair, if necessary. The proposed AD also would require modification of rib 5.0 by the installation of a stiffener to the torsion box; this modification would be preceded by an eddy current inspection to detect fatigue cracking, and repair, if necessary. Accomplishment of this modification would terminate the requirement for repetitive eddy current inspections. In addition, the proposed AD would require another modification of rib 5.0 by cold-expanding certain bolt holes on the torsion box. These actions would be required to be accomplished in accordance with the applicable service bulletins described previously. Differences Between the Proposed Rule and the Service Bulletins If any cracking is detected during an eddy current inspection of the left-hand and right-hand flanges and finger strips at rib 5.0 of the vertical stabilizer, the proposed rule would require that the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate approve the method of repair. The applicable Fokker service bulletins do not provide instructions for repair, but recommend that Fokker be contacted prior to repairing fatigue cracks at rib 5.0. Other Related Rulemaking Actions The FAA has issued AD 91-18-15, amendment 39-8018 (56 FR 43548, September 3, 1991), which requires reinforcement of the left-hand and right-hand flanges of rib 5.0 of the vertical stabilizer by the installation of reinforcing finger clips, in accordance with Fokker Service Bulletin F100-55-014, dated November 29, 1990. That AD was prompted by reports of cracking in the flange of the torsion box at the junction of rib 5.0 and intermediate spar I; it is applicable to Fokker Model F28 Mark 0100 series airplanes having serial numbers 11244 through 11335. The reinforcement required by AD 91-18-15 is to be installed prior to the accumulation of 6,000 total landings on the airplane, or within 100 days after October 8, 1991 (the effective date of that AD), whichever is later. Under the proposed AD, however, this modification would not have to be installed if the addition of steel reinforcement to the torsion box [as specified in proposed paragraph (b)(2)] is accomplished before an airplane has accumulated 6,000 total landings. Cost Impact The FAA estimates that 122 Fokker Model F28 Mark 0100 series airplanes of U.S. registry would be affected by this proposed AD. Approximately 77 airplanes would be required to conduct repetitive inspections of the left-hand and right-hand flanges and finger strips at rib 5.0 of the vertical stabilizer. It would take approximately 10 work hours per airplane to accomplish each proposed inspection. The average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed inspection requirement on U.S. operators of these airplanes is estimated to be $46,200, or $600 per airplane, per inspection. Approximately 77 airplanes also would be required to accomplish the proposed installation of steel reinforcement in the torsion box at rib 5.0 of the vertical stabilizer. It would take approximately 170 work hours per airplane to accomplish this modification (including a pre- modification inspection). The average labor rate is $60 per work hour. Required parts would cost approximately $27,000. Based on these figures, the cost impact of this proposed action on U.S. operators of these airplanes is estimated to be $2,864,400, or $37,200 per airplane. Approximately 122 airplanes would be required to accomplish the proposed cold expansion of holes in the torsion box at rib 5.0 of the vertical stabilizer. It would take approximately 17 work hours per airplane to accomplish this modification, or approximately 8 work hours per airplane if this proposed action is done at the same time as the proposed installation of steel reinforcement. The average labor rate is $60 per work hour. Required parts would cost approximately $206. Based on these figures, the cost impact of this proposed action on U.S. operators of these airplanes is estimated to be between $83,692 and $149,572, or between $686 and $1,226 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. [[Page 1868]] Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: Fokker: Docket 96-NM-185-AD. Applicability: Model F28 Mark 0100 series airplanes having the serial numbers specified in Table 1 of this AD; certificated in any category. Table 1.--Serial Numbers of Airplanes Subject to This AD 11244 through 11460, inclusive 11463 through 11469, inclusive 11471 11474 through 11483, inclusive 11489 through 11491, inclusive 11497 through 11499, inclusive 11501 11502 11504 11506 11507 11512 through 11515, inclusive 11517 11520 Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (e) 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 prevent fatigue cracking in the vertical stabilizer, which consequently could reduce its structural integrity, accomplish the following: (a) For airplanes having serial numbers 11244 through 11419, inclusive, and 11421: Except as provided by paragraph (c) of this AD, prior to the accumulation of 8,500 total landings or within 30 days after the effective date of this AD, whichever occurs later, perform an eddy current inspection to detect fatigue cracking in the left-hand and right-hand flanges and finger strips at rib 5.0 of the vertical stabilizer, in accordance with Fokker Service Bulletin SBF100-55-019, Revision 1, dated May 19, 1993. (1) If no cracking is detected, repeat this inspection thereafter at intervals not to exceed 2,000 landings until the requirements of paragraph (b) of this AD are accomplished. (2) If any cracking is detected, prior to further flight, repair in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. (b) For airplanes with serial numbers 11244 through 11419, inclusive, and 11421, accomplish the requirements of both paragraphs (b)(1) and (b)(2) of this AD: (1) Except as provided by paragraph (c) of this AD, prior to the accumulation of 13,500 total landings, or within 6 months after the effective date of this AD, whichever occurs later, perform an eddy current inspection to detect fatigue cracking in the left-hand and right-hand flanges and finger strips at rib 5.0 of the vertical stabilizer, in accordance with Part 1 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-55-018, Revision 1, dated December 27, 1993. (i) If no cracking is detected, prior to further flight, accomplish the requirements of paragraph (b)(2) of this AD. (ii) If any cracking is detected, prior to further flight, repair in accordance with a method approved by the Manager, Standardization Branch, ANM-113, and accomplish the requirements of paragraph (b)(2) of this AD. (2) After accomplishing the requirements of paragraph (b)(1) of this AD, modify rib 5.0 of the vertical stabilizer by installing new stiffening, in accordance with Part 2 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-55-018, Revision 1, dated December 27, 1993. Accomplishment of this modification constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD. (c) The following exceptions apply with regard to the requirements of paragraphs (a) and (b) of this AD: (1) Accomplishment of the inspection specified in paragraph (a) and (b)(1) of this AD is not required if the modification specified in paragraph (b)(2) is accomplished prior to the accumulation of 7,300 total landings on the airplane. (2) Compliance with AD 91-18-15, amendment 39-8018, is not required if the requirements of paragraph (b)(2) of this AD are accomplished prior to the accumulation of 6,000 total landings on the airplane. (d) For all airplanes: At the applicable times specified in paragraph (d)(1) or (d)(2), modify the Hi-lok bolt holes at rib 5.0 of the vertical stabilizer by cold expansion, in accordance with Fokker Service Bulletin SBF100-55-023, dated January 3, 1995. (1) For airplanes that have been modified in accordance with the requirements of paragraph (b) of this AD prior to the effective date of this AD: Modify prior to the accumulation of either 10,000 landings after in-service modification, or 10,000 landings after delivery with factory modification, as applicable; or within 30 days after the effective date of this AD, whichever occurs later. (2) For all other airplanes: Modify concurrent with accomplishing the requirements of paragraph (b) of this AD. (e) 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, Standardization Branch, ANM-113. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113. (f) 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. Issued in Renton, Washington, on January 8, 1997. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-883 Filed 1-13-97; 8:45 am] BILLING CODE 4910-13-U