AD 2002-08-10

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 to identify all alloy steel bolts on the body station 1480 bulkhead splice, and corrective action if necessary. This action provides for optional terminating action for certain requirements of this AD. This action is necessary to detect and correct cracked or broken bolts, which could result in structural damage and rapid depressurization of the airplane. This action is intended to address the identified unsafe condition.

Final rule; request for comments.

2002-08-10 Boeing: Amendment 39-12718. Docket 2002-NM-69-AD. \n\n\tApplicability: Model 747 series airplanes, certificated in any category, line numbers 1 through 750 inclusive, excluding airplanes on which the bulkhead splice areas have been modified in accordance with Plan "B" of AD 2001-11-06, amendment 39-12248. \n\n\tNote 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 (g) 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 detect and correct cracked or broken alloy steel bolts on the body station (BS) 1480 bulkhead splice and consequent structural damage and rapid depressurization of the airplane, accomplish the following: \n\nInspection \n\n\t(a) At the applicable time specified by paragraph (a)(1) or (a)(2) of this AD: Inspect the BS 1480 bulkhead splice to identify all alloy steel bolts by using a magnet or, if applicable, detailed visual methods, in accordance with Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002. \n\n\tNote 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\n\t\t(1) For airplanes on which the bulkhead splice inspection specified by AD 2001-11-06 has NOT been accomplished within 15 months before the effective date of this AD: Inspect within 90 days after the effective date of this AD. \n\n\t\t(2) For airplanes on which the bulkhead splice inspection specified by AD 2001-11-06 HAS been accomplished within 15 months before the effective date of this AD: Inspect within 18 months since the most recent inspection. \n\nCorrective Actions \n\n\t(b) For each alloy steel bolt found during the inspection required by paragraph (a) of this AD: Before further flight, inspect those bolts using torque test or ultrasonic methods to detect cracks or breakage, in accordance with Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002, except as required by paragraph (e) of this AD.(1) For each uncracked and unbroken alloy steel bolt found: Repeat the inspection specified by paragraph (b) of this AD thereafter at least every 18 months, until the optional terminating action of paragraph (d) of this AD is accomplished. \n\n\t\t(2) For any cracked or broken bolt found: Before further flight, replace it with an Inconel 718 bolt. Such replacement terminates the requirements of this AD for that bolt only. \n\n\t\t(3) If any cracked or broken bolt is found anywhere along the splice during any inspection required by paragraph (b) of this AD: Before further flight, reinspect, using ultrasonic methods, any remaining alloy steel bolts that were initially inspected using torque test methods, and replace any cracked or broken bolt with an Inconel 718 bolt. Such replacement terminates the requirements of this AD for that bolt only. \n\nMagnetic Particle Inspection \n\n\t(c) Plan "A" inspections required by AD 2001-11-06 are acceptable for compliance with the inspection requirements of paragraph (b) of this AD, provided a magnetic particle inspection and applicable corrective actions are performed on any alloy steel bolt removed during any Plan "A" inspection before the bolt is reinstalled. The magnetic particle inspection and corrective actions must be performed in accordance with Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002, except as required by paragraph (e) of this AD. \n\nOptional Terminating Action \n\n\t(d) Replacement of all alloy steel bolts in the BS 1480 bulkhead splice with Inconel 718 bolts, in accordance with Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002, except as required by paragraph (e) of this AD, terminates the requirements of this AD. \n\nExceptions to Service Information \n\n\t(e) If Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002, specifies to contact Boeing for appropriate action: Before further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. \n\nSpares \n\n\t(f) As of the effective date of this AD, no person may install an alloy steel bolt on the BS 1480 bulkhead splice on any airplane. \n\nAlternative Methods of Compliance \n\n\t(g) 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 ACO, FAA. 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. \n\n\tNote 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(h) 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. \n\nIncorporation by Reference \n\n\t(i) Except as required by paragraph (e) of this AD: The actions must be done in accordance with Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002. 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\nEffective Date \n\n\t(j) This amendment becomes effective on May 8, 2002.

The FAA has received reports of broken alloy steel bolts on the body station (BS) 1480 bulkhead splice on Boeing Model 747 series airplanes. This splice connects the upper and lower pieces of the BS 1480 bulkhead and the overwing longeron. The maximum number of broken bolts found on an airplane was 10; that airplane was shown to be unable to withstand limit load. Broken splice bolts were found on one airplane with only 6,229 total flight cycles and 37,440 total flight hours. All of the broken splice bolts found on the airplanes were made from H11 alloy steel, which has been found to be susceptible to stress corrosion and consequent cracking and breakage. Cracked or broken bolts on the bulkhead splice, if not corrected, could result in structural damage and rapid depressurization of the airplane. \n\nRelated AD \n\n\tAD 2001-11-06, amendment 39-12248 (66 FR 31124, June 11, 2001), applicable to certain Boeing Model 747 series airplanes, requires, among other things, repetitive inspections to detect cracking of certain areas of the BS 1480 bulkhead. AD 2001-11-06 focuses more on the skin splice plate and outer chord splice fitting than the mating bolts. However, airplanes on which the bulkhead splice areas have been modified in accordance with AD 2001-11-06 are excluded from the applicability of this AD. Also, inspections of the bulkhead splice area in accordance with AD 2001-11-06 meet the inspection requirements of this AD, provided that the bolts are inspected using magnetic particle methods before they are reinstalled. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 747-53A2477, dated February 28, 2002, which describes procedures for a one-time inspection using a magnet to identify all alloy steel bolts on the BS 1480 bulkhead splice, and an inspection using torque test or ultrasonic methods of all alloy steel bolts to determine if any are cracked or broken. Corrective actions include replacement of any cracked or broken alloy steel bolts with Inconel 718 bolts; an ultrasonic inspection--if any bolt on the splice was found cracked--of any remaining alloy steel bolt that was inspected using torque test methods; and repetitive inspections of the remaining serviceable alloy steel bolts. The alert service bulletin specifies that replacement of all alloy steel bolts on the splice eliminates the need for the corrective actions for the alloy steel bolts. \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 detect and correct cracked or broken bolts on the BS 1480 bulkhead splice, which could result in structural damage and rapid depressurization of the airplane. This action is intended to address the identified unsafe condition. This AD requires accomplishment of the actions specified in the alert service bulletin described previously, except as described below. \n\nDifferences Between AD and Alert Service Bulletin \n\n\tAlthough 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 a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle Aircraft Certification Office, to make such findings. \n\nInterim Action \n\n\tThis is considered to be interim action. The FAA is currently considering requiring the replacement of all alloy steel bolts on the BS 1480 bulkhead splice, which would terminate the torque tests and ultrasonic inspections required by this AD. However, the planned compliance time for this action is long enough to provide adequate notice and opportunity for prior public comment.Determination 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\tSubmit comments using the following format: \n\nOrganize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues. \n\nFor each issue, state what specific change to the AD is being requested. \n\n Include justification (e.g., reasons or data) for each request. \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.Commenters 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 2002-NM-69-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132. \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\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: