[Federal Register Volume 59, Number 15 (Monday, January 24, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-1542] [[Page Unknown]] [Federal Register: January 24, 1994] VOL. 59, NO. 15 Monday, January 24, 1994 ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 93-NM-189-AD] Airworthiness Directives; Boeing Model 747 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 Boeing Model 747 series airplanes. This proposal would require inspections to detect cracking in certain fuselage upper deck tension ties, and repair or modification of any cracked tension ties. This proposal is prompted by reports of fatigue cracking in tension ties. The actions specified by the proposed AD are intended to prevent failure of two or more tension ties and the resultant rapid decompression of the airplane. DATES: Comments must be received by March 21, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-189-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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: Steven C. Fox, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2777; fax (206) 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 93-NM-189-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. 93-NM-189-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion Recently, the FAA has received reports of fatigue cracking in the tension ties on several Boeing Model 747 series airplanes. Most of the cracks were found in the aft channel of the tension tie. These cracks usually occurred in the upper flange of the aft channel of the tension tie. Only one crack was found in the forward channel of the tension tie. The cause of this fatigue cracking has been attributed to the tension ties bending under cabin pressurization loads. This condition, if not corrected, could result in rapid decompression of the airplane in the event of failure of two or more tension ties. These reports of fatigue cracks were received in response to the Supplemental Structural Inspection Program, which was required to be implemented by AD 93-06-01, Amendment 39-8526 (58 FR 19571, April 15, 1993). The purpose of that AD is to implement an inspection program that detects the potential for cracking in specific areas of the airplane that are critical for flight safety. Whenever cracks are found in a Structural Significant Item, the FAA takes rulemaking action to correct these findings of an unsafe condition. This proposal is in response to such a finding. On September 4, 1984, the FAA issued AD 84-19-01, amendment 39-4913 (49 FR 36365, September 17, 1984), to require inspections of the tension tie at body station (BS) 760 on a certain group of Model 747 series airplanes, and at BS 780 on certain other Model 747 series airplanes. The inspections proposed by this rulemaking action do not retract the inspection requirements of that AD. The FAA has reviewed and approved Boeing Service Bulletin 747-53- 2371, dated July 29, 1993, that describes procedures for repetitive detailed visual inspections of the outboard ends of certain tension ties, and repair or modification of cracked tension ties. This modification entails trimming the cracked portion of the channel of the tension tie. 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 repetitive detailed visual inspections of the outboard ends of certain tension ties, and repair or modification of cracked tension ties. The actions would be required to be accomplished in accordance with the service bulletin described previously. There are approximately 203 Boeing Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 113 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 5 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $31,075, or $275 per airplane. This total cost figure assumes that no operator has yet accomplished the proposed requirements of this AD action. 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 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES- 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: Boeing: Docket 93-NM-189-AD. Applicability: Model 747 series airplanes, as listed in Boeing Service Bulletin 747-53-2371, dated July 29, 1993, certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent rapid decompression of the airplane due to failure of two or more tension ties, accomplish the following: (a) Prior to the accumulation of 1,000 flight cycles after the effective date of this AD, unless accomplished previously within the last 2,000 flight cycles, perform a detailed visual inspection to detect cracking of the outboard end tension ties, in accordance with Boeing Service Bulletin 747-53-2371, dated July 29, 1993. (1) If no cracking is detected, repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles until the repair or modification required by paragraph (a)(2) of this AD is accomplished. (2) If any cracking is detected, prior to further flight, repair or modify the cracked tension tie in accordance with the service bulletin. Accomplishment of this repair or modification terminates the repetitive inspection requirement of paragraph (a) of this AD. Note 1: Although AD 84-19-01, amendment 39-4913, requires inspections of the tension ties at body station (BS) 760 on a certain group of Model 747 series airplanes, and at BS 780 on certain other Model 747 series airplanes, the inspections required by this AD do not retract the inspection requirements of that AD. (b) Prior to the accumulation of 10,000 flight cycles following repair or modification of any tension tie, perform a detailed visual inspection to detect cracking of the repaired or modified outboard end tension tie in accordance with Boeing Service Bulletin 747-53- 2371, dated July 29, 1993. (1) If no cracking is detected, repeat this inspection thereafter at intervals not to exceed 6,000 flight cycles. (2) If any cracking is detected, prior to further flight, repair or modify in accordance with the service bulletin, and repeat the inspection required by paragraph (b) of this AD. (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. (d) Special flight permits may be issued in accordance with FAR 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 18, 1994. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-1542 Filed 1-21-94; 10:00 am] BILLING CODE 4910-13-U