# AD 98-13-35: Airworthiness Directives; McDonnell Douglas Model DC-9 and DC-9- 80 Series Airplanes, Model MD-88 Airplanes, and C-9 (Military) Series Airplanes - Type: Airworthiness directive - Effective: July 30, 1998 - Published: June 25, 1998, 63 FR 34585–34587 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Amendment: 39-10626 - Docket: 96-NM-203-AD - Official PDF: https://openairdocs.org/files/sha256/1a/1e/1a1e083e0944b680b95fc4d1ecb2b07a344ed5fab04bb441bf7481a74287014a (from https://www.govinfo.gov/content/pkg/FR-1998-06-25/pdf/98-16695.pdf) - Federal Register: https://www.federalregister.gov/documents/1998/06/25/98-16695/airworthiness-directives-mcdonnell-douglas-model-dc-9-and-dc-9--80-series-airplanes-model-md-88 - Page: https://openairdocs.org/ad/98-13-35 ## Summary This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes, that requires repetitive high frequency eddy current inspections of certain areas of the fuselage to detect cracks of the skin and/or longeron, and various follow-on actions. This amendment also requires installation of a preventative modification, which terminates the repetitive inspections. This amendment is prompted by reports indicating that, due to material fatigue caused by installation preload and cabin pressurization cycles, fatigue cracks were found in the skin and longerons of the fuselage. The actions specified by this AD are intended to prevent such fatigue cracks, which could result in loss of the structural integrity of the fuselage and, consequently, lead to rapid depressurization of the airplane. ## The airworthiness directive ### 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: 98-13-35 McDonnell Douglas: Amendment 39-10626. Docket 96-NM-203-AD. Applicability: Model DC-9-10, -20, -30, -40, and -50 series airplanes; Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83), and -87 (MD-87) series airplanes; Model MD-88 airplanes; and C-9 (military) series airplanes; as listed in McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993; 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 (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. Compliance: Required as indicated, unless accomplished previously. To prevent fatigue cracks in the skin and longerons of the fuselage, which could result in loss of the structural integrity of the fuselage and, consequently, lead to rapid depressurization of the airplane, accomplish the following: ### (a) (a) Perform a high frequency eddy current (HFEC) inspection of the external areas of the fuselage to detect cracks of the skin and/ or longeron between stations Y=160.000 and Y=218.000, in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993; and of the entire area between stations Y=160.000 and Y=180.000, longeron 4 left and longeron 5 left. Perform the inspection at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable. Note 2: Where there are differences between this AD and the referenced service bulletin, the AD prevails. (1) For airplanes other than those identified in paragraph (a)(2) of this AD: Inspect prior to the accumulation of 30,000 total landings, or within 8,000 landings after the effective date of this AD, whichever occurs later. (2) For airplanes that have been inspected previously in accordance with Task C46-53300 of the Corrosion Prevention and Control Program (CPCP), as required by AD 92-22-8-R1, amendment 39-8591, within 6,000 flight cycles prior to the effective date of this AD: Inspect within 12,000 landings after the effective date of this AD. ### (b) (b) Condition 1 (No Cracks). If no crack is detected during any inspection required by this AD, accomplish either paragraph (b)(1) or (b)(2) of this AD, in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. (1) Condition 1, Option I (Repetitive Inspection). Repeat the HFEC inspection required by paragraph (a) of this AD, and the aided visual inspection specified in paragraph 2.E. of the Accomplishment Instructions of the service bulletin, at intervals not to exceed 10,000 landings. (2) Condition 1, Option II (Terminating Action Modification). Accomplish the preventative modification installation of clips and doublers between stations Y=160.000 and Y=218.000, in accordance with the service bulletin. Accomplishment of the modification constitutes terminating action for the repetitive inspection requirements of this AD. ### (c) (c) Condition 2 (Skin Cracks). If any skin crack is detected during any inspection required by this AD, prior to further flight, repair it in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. After repair, accomplish either paragraph (b)(1) or (b)(2) of this AD. ### (d) (d) Condition 3 (Longeron Cracks). If any longeron crack is detected during any inspection required by this AD, prior to further flight, repair it in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. After repair, accomplish either paragraph (b)(1) or (b)(2) of this AD. ### (e) (e) Prior to the accumulation of 100,000 total landings, or within 4 years after the effective date of this AD, whichever occurs later, accomplish the preventative modification specified in paragraph 2.J. of the Accomplishment Instructions of McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. Accomplishment of the modification constitutes terminating action for the requirements of this AD. ### (f) (f) 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, 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. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. ### (g) (g) 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. ### (h) (h) The actions shall be done in accordance with McDonnell Douglas DC-9 Service Bulletin 53-235, dated September 15, 1993. 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, Transport Airplane Directorate, 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. ### (i) (i) This amendment becomes effective on July 30, 1998. Issued in Renton, Washington, on June 17, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. ## Rule preamble ### Dates Effective July 30, 1998. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of July 30, 1998. ### Addresses The service information referenced in this AD 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). This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, 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. ### For further information contact Brent Bandley, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (562) 627-5237; fax (562) 627-5210. ### Supplementary information A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes was published in the Federal Register on March 7, 1997 (62 FR 10492). That action proposed to require repetitive high frequency eddy current (HFEC) inspections of the external areas of the fuselage skin to detect cracks of the skin and/or longeron between stations Y=160.000 and Y=218.000, and various follow-on actions. That action also proposed to require the installation of a preventative modification, which would constitute terminating action for the repetitive inspection requirements. ### Explanation of Changes Made to Proposed AD Since issuance of the NPRM, the FAA has received a report indicating that, during inspection of a McDonnell Douglas Model DC-9-32 series airplane, fatigue cracking was found in additional structure that is within the subject area of the proposed AD (i.e., between stations Y=160.000 and Y=218.000). The additional area is approximately 10 inches by 6 inches and is directly between areas subject to the proposed inspection required by this AD. Because of the small size of the additional area and its location, the FAA finds that adding this area to the existing requirements of the final rule will not increase significantly the inspection burden on operators. Therefore, in addition to the area between stations Y=160.000 and Y=218.000 (as specified in McDonnell Douglas DC-9 Service Bulletin 53-235, which was referenced in the proposed AD as the appropriate source of service information), the FAA has determined that the repetitive HFEC inspections also must be conducted in the entire area between stations Y=160.000 and Y=180.000, longeron 4 left and longeron 5 left. The FAA has revised paragraph (a) of the final rule accordingly, and has added one work hour to the cost impact information below, to account for the additional time necessary to accomplish the required inspection. In addition, McDonnell Douglas is planning on revising the referenced service bulletin to coincide with the requirements of this final rule. ### Comments Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. Several commenters support the proposed rule. ### Request to Allow Credit for Inspections Performed Previously One commenter requests that the compliance time for paragraph (a) of the proposed AD be revised to allow credit for internal visual inspections performed previously in accordance with Task C46-53300 of the Corrosion Prevention and Control Program (CPCP) [required by AD 92-22-08 R1, amendment 39-8591 (58 FR 32281, June 9, 1993)]. The commenter states that, since the primary failure mode is a cracked longeron or shear clip, the internal visual inspection will have a crack detection threshold lower than that of the initial external eddy current inspection specified in paragraph (a) of the proposed AD. The FAA concurs. The FAA finds that the structure and area specified in this AD are identical to the structure and area being inspected in accordance with the CPCP AD 92-22-08 R1. The FAA has determined that, for airplanes that have been inspected previously in accordance with Task C46-53300 of the CPCP (required by AD 92-22-08 R1) within 6,000 landings prior to the effective date of this AD, the initial HFEC inspection required by this AD shall be accomplished within 12,000 landings. The FAA finds that a 12,000-landing compliance time represents an appropriate interval of time allowable for these affected airplanes to continue to operate without compromising safety. The FAA has revised paragraph (a) of the final rule accordingly. ### Conclusion After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. ### Cost Impact There are approximately 1,728 McDonnell Douglas Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,152 airplanes of U.S. registry will be affected by this AD. It will take approximately 17 work hours per airplane to accomplish the required HFEC inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the HFEC inspection required by this AD on U.S. operators is estimated to be $1,175,040, or $1,020 per airplane, per inspection cycle. It will take approximately 89 work hours per airplane to accomplish the required modification, at an average labor rate of $60 per work hour. The cost of required parts will range from $13,771 to $15,292 per airplane. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be between $22,015,872 ($19,111 per airplane) and $23,768,064 ($20,632 per airplane). The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the 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 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. For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. ### List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. ### Adoption of the Amendment Accordingly, 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: ## Related documents - [Proposed rule 96-NM-203-AD](https://openairdocs.org/proposed/96-NM-203-AD): Notice of proposed rulemaking (NPRM), published Mar 7, 1997 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.