AD 98-16-13

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This action requires a one-time inspection for missing fasteners of the splice fitting of the forward inner chord of the Body Station (BS) 2598 bulkhead; and corrective actions, if necessary. This amendment is prompted by a report that fasteners were missing from the splice fitting of the forward inner chord. The actions specified in this AD are intended to prevent accelerated fatigue cracking of the inner chords of the BS 2598 bulkhead, which could result in inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the airplane.

Final rule; request for comments

98-16-13 BOEING: Amendment 39-10689. Docket 98-NM-210-AD. \n\n\tApplicability: Model 747 series airplanes, line positions 1 through 1157; certificated in any category. \n\n\tNOTE 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. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo preventaccelerated fatigue cracking of the inner chords of the Body Station (BS) 2598 bulkhead, which could result in inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the airplane; accomplish the following: \n\n\t(a)\tPrior to the accumulation of 8,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, perform a one-time visual inspection for missing fasteners of the splice fitting of the forward inner chord of the BS 2598 bulkhead, on the left and right sides of the airplane, in accordance with Boeing Alert Service Bulletin 747-53A2423, dated June 11, 1998. \n\n\t\t(1)\tIf all fasteners are present, no further action is required by this AD. \n\t\t(2)\tIf any fastener is missing, prior to further flight, accomplish a detailed visual inspection and a high frequency eddy current inspection to detect cracking of the forward and aft inner chords of the BS 2598 bulkhead, on the left and rightsides of the airplane; in accordance with the alert service bulletin. \n\n\t\t\t(i)\tIf no cracking is detected, prior to further flight, install the fasteners, in accordance with the alert service bulletin. \n\n\t\t\t(ii)\tIf any cracking is detected, prior to further flight, repair the cracking and install the fasteners, in accordance with Boeing 747 Structural Repair Manual (SRM) 53-10-04, Figure 72, or Boeing 747SP SRM 53-19-02, Figure 41; as applicable; or repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t(b)\tWithin 10 days after accomplishing the inspection required by paragraph (a) of this AD, submit a report of the inspection results (findings of missing fasteners only) to the Manager, Seattle Manufacturing Inspection District Office, FAA, Transport Airplane Directorate, 2500 East Valley Road, suite C-2, Renton, Washington 98055-4056; fax (425) 227-1181. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056. \n\n\t(c)\tAn 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 ACO. Operators shall submit their requests through an appropriate FAA Principal \nMaintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(d)\tSpecial 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. \n\n\t(e)\tExceptas provided by paragraph (a)(2)(ii) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2423, dated June 11, 1998. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(f)\tThis amendment becomes effective on August 18, 1998.

The FAA has received a report indicating that fasteners were missing from the splice fitting of the forward inner chord of the Body Station (BS) 2598 bulkhead on a Boeing Model 747 series airplane. The fasteners missing from the splice fitting resulted in accelerated initiation and propagation of fatigue cracking of both the forward and aft inner chords of the BS 2598 bulkhead. A 0.2-inch crack was found in the forward inner chord, and a 3.0-inch horizontal crack and a 1.0-inch vertical crack were found in the aft inner chord. Such fatigue cracking, if not corrected, could result in inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the airplane. \n\n\tAs a result of the report of missing fasteners, Boeing requested that operators perform inspections on a limited number of delivered airplanes. Sixteen airplanes were inspected, including ten that had been delivered at approximately the same time as the airplane on which cracks were found. The fasteners were found to be installed on all 16 of those airplanes. However, Boeing has not been able to provide justification to limit the inspection for missing fasteners to a specific group of airplanes, so this AD requires an inspection for missing fasteners on all Boeing Model 747 series airplanes that have been delivered. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 747-53A2423, dated June 11, 1998, which describes procedures for a one-time visual inspection for missing fasteners of the splice fitting of the forward inner chord of the BS 2598 bulkhead; and corrective actions, if any fasteners are missing. The corrective actions include performing a detailed visual inspection and a high frequency eddy current inspection for cracking of the forward and aft inner chords of the BS 2598 bulkhead, on the left and right sides of the airplane; repair, if necessary; and installation of the fasteners. \n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent accelerated fatigue cracking of the inner chords of the BS 2598 bulkhead, which could result in inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the airplane. This AD requires accomplishment of the actions specified in the alert service bulletin described previously, except as discussed below. This AD also requires that operators report results of inspection findings (findings of missing fasteners only) to the FAA. \n\nInterim Action \n\n\tThis is considered to be interim action. There have been other reports of fatigue cracking of the inner chords of the BS 2598 bulkhead, as well as cracking of repair angles that were installed to correct cracks that were detected previously in the inner chords of the bulkhead. The FAA is currently considering additional rulemaking to further address the unsafe condition of fatigue cracking in the inner chords of the BS 2598 bulkhead. However, the planned compliance time for the corrective actions is sufficiently long so that notice and opportunity for prior public comment will be practicable. \n\nDifferences Between This Rule and Alert Service Bulletin \n\n\tOperators should note that the statement of effectivity in the alert service bulletin does not include the Boeing Model 747 series airplane having line position 1155. That airplane is currently in storage and has not been delivered. Boeing is under contract to accomplish any required inspections prior to delivery of the airplane. Therefore, the applicability statement of this AD includes this airplane. \n\n\tOperators also should note that, although the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this AD requires the repair of those conditions to be accomplished in accordance with Boeing 747 Structural Repair Manual (SRM) 53-10-04, Figure 72; or Boeing 747SP SRM 53-19-02, Figure 41; as applicable; or in accordance with a method approved by the FAA. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-NM-210-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:\n\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: