AD 98-04-07

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9 and C-9 (military) series airplanes, that currently requires eddy current or dye penetrant inspection for cracks in the upper fuselage skin in the area of the aft pressure bulkhead tee. This amendment requires new improved repetitive inspections and follow-on actions, and expands the applicability of the existing AD to include additional airplanes. This amendment is prompted by additional reports of fatigue cracking and improperly seated attachments in the upper fuselage skin in the area of the aft pressure bulkhead tee. The actions specified in this AD are intended to detect and correct such fatigue cracking, which could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane.

Final rule; request for comments.

98-04-07 MCDONNELL DOUGLAS: Amendment 39-10320. Docket 98-NM-12-AD. Supersedes AD 81-26-03 R1, Amendment 39-4394 which amended Amendment 39-4282. \n\n\tApplicability: Model DC-9-10, -20, -30, -40, -50 series airplanes, Model DC-9-81 (MD-81) and DC-9-82 (MD-82) series airplanes, and C-9 (military) series airplanes; as listed in McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997; 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 (f) 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 fatigue cracking in the upper fuselage skin in the area of the aft pressure bulkhead tee, which could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane, accomplish the following: \n\n\tNOTE 2: Where there are differences between the alert service bulletin and the AD, the AD prevails. \n\n\t(a)\tPrior to the accumulation of 30,000 total landings, or within 25 days after the effective date of this AD, whichever occurs later, perform a visual inspection of the fuselage upper skin splice at the aft pressure bulkhead between longerons 14 left and 14 right to determine if an internal production titanium doubler has been installed. \n\n\t\t(1)\tIf results of the visual inspection reveal that an internal production titanium doubler has not been installed, prior to further flight, perform a visual inspection of the fuselage upper skin splice area at the aft pressure bulkhead between longerons 14 left and 14 right to determine if a permanent repair has been installed in accordance with McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 2, dated June 3, 1981; Revision 3, dated November 22, 1981; Revision 4, dated October 25, 1983; or Revision 05, dated November 24, 1997. \n\n\t\t\t(i)\tIf a permanent repair has been installed, no further action is required by this AD. \n\n\t\t\t(ii)\tIf a permanent repair has not been installed, and if a dye penetrant or HFEC inspection has been accomplished in accordance with AD 81-26-03 R1, within 4,000 landings following accomplishment of the last dye penetrant or HFEC inspection required by AD 81-26-03 R1, or within 90 days after the effective date of this AD, whichever occurs later, perform an HFEC inspection to detect skin cracks or failed fasteners of the unmodified area, in accordance with the Accomplishment Instructions of the alert service bulletin. \n\n\t\t\t(iii)\tIf a permanent repair has not been installed, and if a dye penetrant or HFEC inspection has not been accomplished in accordance with AD 81-26-03 R1, prior to further flight, perform a high frequency eddy current (HFEC) inspection to detect skin cracks or failed fasteners of the unmodified area, in accordance with the Accomplishment Instructions of the alert service bulletin. \n\n\t\t(2)\tIf results of the visual inspection reveal that an internal production titanium doubler has been installed, perform an HFEC inspection to detect skin cracks or failed fasteners of the upper skin splice area at the tee cap of the aft fuselage pressure bulkhead between longerons 14 left and 14 right, in accordance with the Accomplishment Instructions of the alert service bulletin at the time specified in paragraph (a)(2)(i) or (a)(2)(ii) of this AD, as applicable. \n\n\t\t\t(i)\tFor airplanes that have been previously inspected using LFEC techniques or have not been previously inspected, in accordance with AD 81-26-03 R1: Inspect within 90 days following accomplishment of the visual inspection required by paragraph (a) of this AD. \n\n\t\t\t(ii)\tFor airplanes that have been inspected previously using HFEC or dye penetrant techniques, in accordance with AD 81-26-03 R1: Inspect within 4,000 landings following accomplishment of the last HFEC or dye penetrant inspection required by AD 81-20-03 R1, or within 90 days following accomplishment of the visual inspection required by paragraph (a) of this AD, whichever occurs later. \n\n\t(b)\tIf no skin crack or failed fastener is detected during any inspection required by this AD, repeat the HFEC inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 4,000 landings. \n\n\t(c)\tIf any failed fastener with no skin crack is detected during any inspection required by this AD, prior to further flight, replace the failed fastener with a new fastener, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997, including Service Sketch 3145B and Service Sketch 3174C (both undated). Repeat the HFEC inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 4,000 landings. \n\n\t(d)\tIf any skin crack is detected during any inspection required by this AD, prior to further flight, accomplish the interim repair in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997, including Service Sketch 3145B and Service Sketch 3174C (both undated). For the unmodified area, repeat the HFEC inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 4,000 landings. \n\n\t(e)\tAccomplishment of the permanent repair in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997, including Service Sketch 3145B and Service Sketch 3174C (both undated), constitutes terminating action for the repetitive inspection requirements of this AD. \n\n\tNOTE 3: The permanent repair is required by AD 96-10-11, amendment 39-9618 (61 FR 24675, May 16, 1996) as part of the DC-9/MD-80 Aging Aircraft Service Action Requirements Document. \n\n\t(f)\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, Los Angeles 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, Los Angeles ACO. \n\n\tNOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. \n\n\t(g)\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(h)\tExcept as provided by paragraphs (a) and (a)(1) of this AD, the inspections, replacement, interim repair, and permanent repair, if accomplished, shall be done in accordance with McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997, including Service Sketch 3145B and Service Sketch 3174C (both undated). 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 The Boeing Company, Douglas Products Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(i)\tThis amendment becomes effective on February 25, 1998.

On May 19, 1982, the FAA issued AD 81-26-03 R1, amendment 39-4394 (47 FR 23697, June 1, 1982), applicable to certain McDonnell Douglas Model DC-9 and C-9 (military) series airplanes, to require eddy current or dye penetrant inspection for cracks in the upper fuselage skin in the area of the aft pressure bulkhead tee. That action was prompted by reports of fatigue cracking in the upper skin and improperly seated attachments in the upper skin splice area at the fuselage aft pressure bulkhead tee between longerons 14 left and 14 right. The actions required by that AD are intended to prevent such fatigue cracking, which could result in structural failure of the fuselage shell, and consequent rapid decompression of the airplane. \n\nActions Since Issuance of Previous Rule \n\n\tSince the issuance of that AD, the FAA has received reports of additional fatigue cracking and improperly seated attachments in the subject area on McDonnell Douglas Model DC-9 series airplanes. These airplanes had accumulated between 57,485 and 67,755 total flight cycles. The FAA has determined that accomplishment of the inspections required by AD 81-26-03 R1 does not adequately preclude fatigue cracking of the upper skin splice on the aft pressure bulkhead of the fuselage. Such fatigue cracking, if not detected and corrected in a timely manner, could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane. \n\n\tThe subject area on certain McDonnell Douglas Model DC-9-80 and C-9 (military) series airplanes is identical to that on the affected Model DC-9 series airplanes. Therefore, all of these airplanes may be subject to the same unsafe condition. \n\nExplanation of Relevant Service Information \n\n\tSubsequent to the finding of this new cracking, the manufacturer issued, and the FAA reviewed and approved, McDonnell Douglas Alert Service Bulletin DC9-53A147, Revision 05, dated November 24, 1997, including Service Sketch 3145B and Service Sketch 3174C (both undated). The revised alert service bulletin describes new, improved procedures for repetitive high frequency eddy current (HFEC) inspections to detect cracks of the upper skin splice area at the tee cap on the aft fuselage pressure bulkhead between longerons 14 left and 14 right; and installation of an interim repair, or replacement of failed fasteners with new fasteners, if necessary. The revised alert service bulletin also provides for an optional terminating permanent repair, which eliminates the need for the repetitive inspections. In addition, the revised alert service bulletin expands the effectivity listing to include additional airplanes that are subject to the addressed unsafe condition. \n\nExplanation of Requirements of Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 81-26-03 R1. This AD requires new, improved repetitive HFEC inspections to detect cracks in the upper skin splice area at the tee cap on the aft fuselage pressure bulkhead between longerons 14 left and 14 right; and installation of an interim repair, or replacement of failed fasteners with new fasteners, if necessary. The AD also provides for an optional terminating permanent repair, which constitutes terminating action for the repetitive inspection requirements. In addition, the AD expands the applicability of the existing AD to include additional airplanes. The actions would be required to be accomplished in accordance with the alert service bulletin described previously.\n\nDifferences Between the AD and the Relevant Service Information \n\n\tOperators should note that this AD differs from the referenced alert service bulletin in that it requires an initial visual inspection of the fuselage upper skin splice at the aft pressure bulkhead between longerons 14 left and 14 right to determine if an internal production titanium doubler has been installed. The referenced alert service bulletin describes procedures for inspection of airplanes on which the doubler has been installed; however, it does not describe procedures for such inspection of airplanes on which the doubler has not been installed. \n\n\tThe FAA has received reports of widespread fatigue-related cracking on airplanes that had been inspected previously in accordance with AD 81-26-03 R1, and on which an internal production titanium doubler had not been installed. In light of this, the FAA finds that an initial one-time visual inspection is necessary to determine if a doubler has been installed. \n\n\tIn addition, for airplanes on which the subject doubler has not been installed, the AD would require a visual inspection of the subject area to determine if an interim or permanent repair has been installed; and follow-on actions, if necessary. (These follow-on actions include repetitive HFEC inspections, replacement of failed fasteners, and accomplishment of an interim repair.) \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-12-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\nPART 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. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-4394 (47 FR 23697, June 1, 1982), and by adding a new airworthiness directive (AD), amendment 39-10320, to read as follows: