[Federal Register Volume 64, Number 160 (Thursday, August 19, 1999)] [Proposed Rules] [Pages 45211-45213] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 99-21575] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 98-NM-351-AD] RIN 2120-AA64 Airworthiness Directives; Boeing Model 737-300, -400, and -500 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 Boeing Model 737-300, -400 and -500 series airplanes. This proposal would require replacement, with new parts, of the existing actuators or the rod ends on the existing actuators at wing leading edge slat positions 1, 2, 5, and 6. This proposal is prompted by reports indicating that the rod ends on several leading edge slat actuators have fractured. The actions specified by the proposed AD are intended to prevent fatigue cracking of the rod ends of the leading edge slat actuators, which could result in uncommanded deployment of the wing leading edge slat and consequent reduced controllability of the airplane. DATES: Comments must be received by October 4, 1999. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-351-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 [[Page 45212]] p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: Robert C. Jones, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone (425) 227-1118; fax (425) 227-1181. 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 98-NM-351-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. 98-NM-351-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The FAA has received reports of fractured rod ends on several actuators for the wing leading edge slats on Boeing Model 737-300, - 400, and -500 series airplanes. One reported case of an actuator rod end fracture resulted in an air turnback after the airplane experienced uncommanded roll during flight. It has been determined that these fractures are the result of fatigue cracking. Failure of the actuator rod end, under certain flight conditions, could result in an uncommanded deployment of the affected wing leading edge slat and consequent reduced controllability of the airplane. Explanation of Relevant Service Information The FAA has reviewed and approved Boeing Alert Service Bulletin 737-27A1211, dated November 19, 1998, which describes procedures for replacement of the existing wing leading edge slat actuator with a new actuator, or replacement of the rod end on the existing leading edge slat actuator. Accomplishment of either of these actions specified in the alert service bulletin is intended to adequately address the identified unsafe condition. Explanation of Requirements of Proposed Rule Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the alert service bulletin described previously. Cost Impact There are approximately 1,897 airplanes of the affected design in the worldwide fleet. The FAA estimates that 720 airplanes of U.S. registry would be affected by this proposed AD. Replacement of the leading edge slat actuator with an actuator that has a new rod end is proposed as one option for compliance with this AD action. Replacement of the actuators on slat positions 1, 2, 5, and 6 would take approximately 3 hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $32,252 per airplane. Based on these figures, the cost impact of the installation of actuators with new rod ends as proposed as an option by this AD on U.S. operators is estimated to be $32,432 per airplane. In lieu of installation of an actuator with a new rod end, this proposed AD provides an option for replacement of the rod ends on the existing actuators. This action would take approximately 4 work hours per airplane, at an average labor rate of $60 per work hour. Required parts would cost between approximately $5,928 and $21,544 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be between $6,168 and $21,784 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: Boeing: Docket 98-NM-351-AD. [[Page 45213]] Applicability: Model 737-300, -400, and -500 series airplanes; line numbers 1001 through 3063 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 (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 prevent fatigue cracking of the rod ends on the leading edge slat actuators, which could result in uncommanded deployment of the wing leading edge slat and consequent reduced controllability of the airplane, accomplish the following: (a) Within 24 months after the effective date of this AD: Replace the leading edge slat actuator with an actuator that has a new rod end, or replace the rod end on the existing slat actuator with a new rod end, at slat positions 1, 2, 5, and 6; in accordance with the Accomplishment Instructions in Boeing Alert Service Bulletin 737-27A1211, dated November 19, 1998. Spares (b) As of the effective date of this AD, no person shall install any part having a part number identified in the ``Existing Part Number'' column of Section 2.E. of Boeing Alert Service Bulletin 737-27A1211, dated November 19, 1998, on any airplane. Alternative Methods of Compliance (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, Seattle 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, Seattle ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permits (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. Issued in Renton, Washington, on August 13, 1999. D. L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-21575 Filed 8-18-99; 8:45 am] BILLING CODE 4910-13-U