AD 98-08-24

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes, that requires a one-time visual inspection to determine if all corners of the forward lower cargo doorjamb have been previously modified. This amendment also requires low frequency eddy current inspections to detect cracks of the fuselage skin and doubler at all corners of the forward lower cargo doorjamb, various follow-on repetitive inspections, and modification, if necessary. This amendment is prompted by fatigue cracks found in the fuselage skin and doubler at the corners of the forward lower cargo doorjamb. The actions specified by 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.

98-08-24 MCDONNELL DOUGLAS: Amendment 39-10473. Docket 97-NM-40-AD. \n\n\tApplicability: Model DC-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes, as listed in McDonnell Douglas Service Bulletin DC9-53-277, dated September 30, 1996; 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 (e) 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 fuselage skin or doubler at the corners of the forward lower cargo doorjamb, 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 service bulletin and the AD, the AD prevails. \n\n\tNOTE 3: This AD is related to AD 96-13-03, amendment 39-9671, (61 FR 31009, June 19, 1996), and will affect Principal Structural Element (PSE) 53.09.001 of the DC-9 Supplemental Inspection Document (SID). \n\n\t(a)\tPrior to the accumulation of 48,000 total landings, or within 3,500 landings after the effective date of this AD, whichever occurs later, perform a one-time visual inspection to determine if the corners of the forward lower cargo doorjamb have been modified prior to the effective date of this AD.(b)\tIf the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward lower cargo doorjamb have not been modified, prior to further flight, perform a low frequency eddy current (LFEC) or x-ray inspection to detect cracks of the fuselage skin and doubler at all corners of the forward lower cargo doorjamb, in accordance with McDonnell Douglas Service Bulletin DC9-53-277, dated September 30, 1996. \n\n\t\t(1)\tIf no crack is detected during the LFEC or x-ray inspection required by this paragraph, accomplish the requirements of either paragraph (b)(1)(i) or (b)(1)(ii) of this AD. \n\n\t\t\t(i)\tOption 1. Repeat the inspections as follows until paragraph (b)(1)(ii) of this AD is accomplished: \n\n\t\t\t\t(A)\tIf the immediately preceding inspection was conducted using LFEC techniques, conduct the next inspection within 3,500 landings. \n\n\t\t\t\t(B)\tIf the immediately preceding inspection was conducted using x-ray techniques, conduct the next inspection within 2,850 landings. \n\n\t\t\t(ii)\tOption 2. Prior to further flight, modify the corners of the forward lower cargo doorjamb, in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of that modification, perform a LFEC inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin. Repeat the LFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t\t\t(A)\tIf no crack is detected on the skin adjacent to the modification during any LFEC or x-ray inspection required by this paragraph, repeat the LFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t\t\t(B)\tIf any crack is detected on the skin adjacent to the modification during any LFEC or x-ray inspection required by this paragraph, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.(2)\tIf any crack is found during any LFEC or x-ray inspection required by this paragraph and the crack is 2 inches or less in length: Prior to further flight, modify it in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform a LFEC inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin. \n\n\t\t\t(i)\tIf no crack is detected during the LFEC inspection required by this paragraph, repeat the LFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t\t(ii)\tIf any crack is detected during the LFEC inspection required by this paragraph, prior to further flight, repair it in accordance with a method approved by the Manager Los Angeles ACO. \n\n\t\t(3)\tIf any crack is found during any LFEC or x-ray inspection required by this paragraph and the crack is greater than 2 inches in length: Prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t(c)\tIf the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward lower cargo doorjamb have been modified, but not in accordance with the DC-9 Structural Repair Manual (SRM) or Service Rework Drawing, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t(d)\tIf the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward lower cargo doorjamb have been modified in accordance with DC-9 SRM or Service Rework Drawing, prior to the accumulation of 28,000 landings since accomplishment of that modification, or within 3,500 landings after the effective date of this AD, whichever occurs later, perform a LFEC inspection to detect cracks on the skin adjacent to the modification, in accordance with McDonnell Douglas Service Bulletin DC9-53-277, dated September 30, 1996. Repeat the LFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t(1)\tIf no crack is detected during any LFEC inspection required by this paragraph, repeat the LFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t(2)\tIf any crack is detected during any LFEC inspection required by this paragraph, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t(e)\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(f)\tSpecialflight 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(g)\tExcept as provided by paragraphs (a), (b)(1)(ii)(B), (b)(2)(ii), (b)(3), (c), and (d)(2) of this AD, the actions shall be done in accordance with McDonnell Douglas Service Bulletin DC9-53- 277, dated September 30, 1996. 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 FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(h)\tThis amendment becomes effective on May 22, 1998.

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-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes was published in the Federal Register on July 25, 1997 (62 FR 39975). That action proposed to require a one-time visual inspection to determine if all corners of the forward lower cargo doorjamb have been modified previously. That action also proposed to require low frequency eddy current (LFEC) inspections to detect cracks of the fuselage skin and doubler at all corners of the forward lower cargo doorjamb, various follow-on repetitive inspections, and modification, if necessary. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. One commenter supports the proposed AD. \n\nPermit Repairs inAccordance with Designated Engineering Representative (DER) Approval \n\n\tOne commenter requests that proposed paragraphs (b)(3) and (c) be revised to permit the repair of cracked structure to be accomplished in accordance with the DER of The Boeing Company, Douglas Products Division for a temporary basis, rather than the Manager of the Los Angeles Aircraft Certification Office (ACO). The commenter states that such an approval would expedite the process for repair approval for a crack condition beyond the allowable repair limits (i.e., greater than 2 inches in length) and for existing repairs that are not in accordance with the DC-9 Structural Repair Manual (SRM) or Service Rework Drawing. \n\n\tThe FAA does not concur that revision of the AD is necessary. The FAA is currently in the process of implementing procedures by which AD-mandated structural repairs may be approved by certain DER's employed by type certificate holders. Once the procedures are implemented, these DER's will beauthorized to issue such approvals, and no change to the AD is necessary to allow for this. Request to Revise Requirements of Proposed AD \n\n\tOne commenter requests that paragraph (c) of the proposed AD be revised to read as follows: \n\n\t"(c) If the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward lower cargo doorjamb have been modified by FAA approved repairs other than the DC- 9 SRM or Service Rework Drawing, prior to further flight, accomplish an initial Low Frequency Eddy Current inspection of the fuselage skin adjacent to the repair. \n\n\t(c)(i) If no cracks are detected, within (6) months after the initial LFEC inspection, accomplish a repair approved by the Manager, Los Angeles ACO. \n\n\t(c)(ii) If cracks are detected, prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles ACO." \n\n\tThis commenter states that, as paragraph (c) of the AD is currently worded, it will cause an unnecessaryoperation impact since FAA-approved non-standard SRM or Service Rework Drawing repairs are known to exist in this area of the doorjamb. The commenter contends that obtaining approval for such repairs from the Los Angeles ACO, prior to further flight, will be time consuming and will result in an unwarranted extended ground time for the airplane. \n\n\tThe FAA does not concur with the commenter's request to revise paragraph (c) of the AD. The FAA in conjunction with McDonnell Douglas has conducted further analysis of this issue. The FAA has determined that, for cargo doorjambs which are found to be modified previously but not in accordance with the DC-9 SRM or Service Rework Drawing, an initial LFEC inspection of the fuselage skin adjacent to those existing repairs will not detect any cracking under the repairs. In light of these findings, no change to the final rule is necessary. \n\nRequest to Revise DC-9 Supplemental Inspection Document (SID) \n\n\tOne commenter requests that, prior toissuance of the final rule, the DC-9 SID be revised to incorporate the actions required by this AD. The commenter states that such a revision will eliminate confusion between the DC-9 SID and the AD. The FAA does not concur. The actions required by this AD are necessary to ensure inspection continuity for the affected Principal Structural Element (PSE). After issuance of the final rule, the manufacturer may revise the DC-9 SID. \n\nRequest to Develop Standard Repairs \n\n\tOne commenter request that, for previously repaired corners and for cracks greater than 2 inches long, McDonnell Douglas develop additional "standard repairs" that are pre-approved by the Manager, Los Angeles ACO, FAA, Transport Airplane Directorate. The commenter contends that the cargo door area is one of the most easily damaged areas on the airplane and that there are many non-SRM or Service Rework Drawing repairs that exist in this area. The commenter states that such an approval would minimize the amount of time required to obtain the approved repair and the impact to flight and maintenance schedules. \n\n\tThe FAA does not concur with the commenter's request to pre-approve "standard repairs." The manufacturer has indicated that it has not received many requests for approval of repairs required by paragraph (b)(3) or (c) of this AD. Therefore, a repair approved by the Manager of the Los Angeles ACO will be developed on a case-by-case basis. In addition, the Manager and staff of the Los Angeles ACO are working very closely with the manufacturer to expedite repair approval requests. Such requests may be made under the provisions of paragraph (e) of the final rule. \n\nConclusion \n\n\tAfter 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 as proposed. \n\nCost Impact \n\n\tThere are approximately 899 McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes of the affected design in the worldwide fleet. The FAA estimates that 622 airplanes of U.S. registry will be affected by this AD. \n\n\tIt will take approximately 1 work hour per airplane to accomplish the required visual inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the visual inspection required by this AD on U.S. operators is estimated to be $37,320, or $60 per airplane. \n\n\tShould an operator be required to accomplish the LFEC inspection, it would take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the LFEC inspection required by this AD on U.S. operators is estimated to be $60 per airplane. \n\n\tShould an operator be required to accomplish the modification, it would take approximately 14 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $936, or $2,807 per airplane, depending on the service kit purchased. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be $1,776 or $3,647 per airplane. \n\n\tThe 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. \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\tFor the reasons discussed above, I certifythat 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." \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 citationfor part 39 continues to read as follows: \n\nAuthority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: