AD 98-23-11

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-31 series airplanes, that requires a one-time visual inspection to determine if all corners of the forward service door doorjamb have been modified previously, various follow-on repetitive inspections, and modification, if necessary. This amendment is prompted by reports of fatigue cracks found in the fuselage skin and doubler at the corners of the forward service door 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.

98-23-11 MCDONNELL DOUGLAS: Amendment 39-10877. Docket 97-NM-99-AD. \n\n\tApplicability: Model DC-9-31 series airplanes, as listed in McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 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 (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 fatigue cracking in the fuselage skin or doubler at the corners of the forward service door 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: The words "repair" and "modify/modification" in this AD and the referenced service bulletin are used interchangeably. \n\n\t(a)\tPrior to the accumulation of 50,000 total landings, or within 3,225 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 service door doorjamb have been modified. Perform the inspection in accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997. \n\n\t(b)\tFor airplanes identified as Group 1 in McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997: If the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward service door 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 service door doorjamb, in accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997. \n\n\t\t(1)\tGroup 1, Condition 1. If no crack is detected during any LFEC or x-ray inspection required by paragraph (b) of this AD, accomplish the requirements of either paragraph (b)(1)(i) or (b)(1)(ii) of this AD, in accordance with the service bulletin. \n\n\t\t\t(i)\tOption 1. Repeat the LFEC inspection required by this paragraph thereafter at intervals not to exceed 3,225 landings, or the x-ray inspection required by this paragraph thereafter at intervals not to exceed 3,075 landings; or \n\n\t\t\t(ii)\tOption 2. Prior to further flight, modify the corner skin of the forward service door doorjamb in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform a high frequency eddy current (HFEC) inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin. \n\n\t\t\t\t(A)\tIf no crack is detected on the skin adjacent to the modification during the HFEC required by this paragraph, repeat the HFEC 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 HFEC 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. \n\n\t\t(2)\tGroup 1, Condition 2. If any crack is found during any LFEC or x-ray inspection required by paragraph (b) of this AD, and the crack is 2 inches or less in length: Prior to further flight, modify/repair the corners of the doorjamb of the forward service door in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform a HFEC 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 HFEC inspection required by this paragraph, repeat the HFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t\t(ii)\tIf any crack is detected during any HFEC 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)\tGroup 1, Condition 3. If any crack is found during any LFEC or x-ray inspection required by paragraph (b) of this AD, and the crack is greater than 2 inches in length: Prior to further flight, repair itin accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t(c)\tGroup 2, Condition 1. For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997: If the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward service door doorjamb have been modified previously in accordance with the McDonnell Douglas DC-9 Structural Repair Manual, using a steel doubler, accomplish either paragraph (c)(1) or (c)(2) of this AD in accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997. \n\n\t\t(1)\tOption 1. Prior to the accumulation of 6,000 landings after accomplishment of that modification, or within 3,225 landings after the effective date of this AD, whichever occurs later, perform an HFEC 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 HFEC inspection required by paragraph (c)(1) of this AD, repeat the HFEC inspection thereafter at intervals not to exceed 3,000 landings. \n\n\t\t\t(ii)\tIf any crack is detected during any HFEC inspection required by paragraph (c)(1) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t\t(2)\tOption 2. Prior to further flight, modify the corner skin of the forward service door doorjamb in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform an HFEC 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 on the skin adjacent to the modification during the HFEC required by this paragraph, repeat the HFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t\t(ii)\tIf any crack is detected on the skin adjacent to the modification during any HFEC 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(d)\tGroup 2, Condition 2. For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997: If the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward service door doorjamb have been modified previously in accordance with McDonnell Douglas DC-9 Structural Repair Manual, using an aluminum doubler, prior to the accumulation of 28,000 landings after accomplishment of that modification, or within 3,225 landings after the effective date of this AD, whichever occurs later, perform an HFEC inspection to detect cracks on the skin adjacent to the modification, in accordance with McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997. \n\n\t\t(1)\tIf no crack is detected on the skin adjacent to the modification during the HFEC required by this paragraph, repeat theHFEC inspection thereafter at intervals not to exceed 20,000 landings. \n\n\t\t(2)\tIf any crack is detected on the skin adjacent to the modification during any HFEC 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)\tGroup 2, Condition 3. For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997: If the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward service door doorjamb have been modified previously, but not in accordance with McDonnell Douglas Structural Repair Manual, prior to further flight, repair the corners in accordance with a method approved by the Manager, Los Angeles ACO. \n\n\t(f)\tAccomplishment of the actions required by this AD constitutes terminating action for inspections of Principal Structural Element (PSE) 53.09.033 (reference McDonnell Douglas Model DC-9 Supplemental Inspection Document) required by AD 96-13-03, amendment 39-9671. \n\n\t(g)\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 ACO. 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(h)\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(i)\tExcept as provided by paragraphs (b)(1)(ii)(B), (b)(2)(ii), (b)(3), (c)(1)(ii), (c)(2)(ii), (d)(2), and (e) of this AD, the actions shall be done in accordance withMcDonnell Douglas Service Bulletin DC9-53-288, dated February 10, 1997. 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 McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department 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. \n\n\t(j)\tThis amendment becomes effective on December 17, 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-9-31 series airplanes was published in the Federal Register on January 27, 1998 (63 FR 3852). That action proposed to require a one-time visual inspection to determine if all corners of the forward service door doorjamb have been modified previously, 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. \n\nRequest to Allow Designated Engineering Representative (DER) Approval of Certain Repairs \n\n\tOne commenter requests that the FAA revise the proposed AD to permit repairs of cracked structure to be accomplished in accordance with the DER of The Boeing Company, Douglas Products Division, on a temporary basis, rather than in accordance with 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 accomplished in accordance with the DC-9 Structural Repair Manual (SRM) or Service Rework Drawing. \n\n\tThe FAA does not concur. While DER's are authorized to determine whether a design or repair method complies with a specific requirement, they are not currently authorized to make the discretionary determination as to what the applicable requirement is. However, the FAA has issued a notice (N 8110.72, dated March 30, 1998), which provides guidance for delegating authority to certain type certificate holder structural DER's to approve alternative methods of compliance for AD-required repairs and modifications of individual airplanes. The FAA is currently working with The Boeing Company, Douglas Products Division, to develop the implementation process for delegation of approval of alternative methods of compliance in accordance with that notice. Once this process is implemented, approval authority for alternative methods of compliance can be delegated without revising the AD. \n\nRequest to Revise Paragraph (e) of the Proposed AD \n\n\tOne commenter requests that paragraph (e) of the proposed AD be revised to read as follows: \n\n\t"(e)\tIf the visual inspection required by paragraph (a) of this AD reveals that the corners of the forward doorjamb of the service door 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(e)\t(i)\tIf no cracks are detected, within (6) months after the initial LFEC inspection, accomplish a repair approved by the Manager, Los AngelesACO. \n\n\t(e)\t(ii)\tIf 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 (e) of the proposed AD is currently worded, it will cause an unnecessary operational impact since FAA-approved non-standard SRM or Service Rework Drawing repairs are known to exist for 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 (e) of the AD. The FAA, in conjunction with McDonnell Douglas, has conducted further analysis of this issue. The FAA has determined that, for doorjambs of the forward service door that are found to be modified previously, but not in accordance with the DC-9 SRM, an initial low frequency eddy current inspection of the fuselage skin adjacent to those existing repairs will not detect any cracking under the repairs. In light of this determination, no change to this final rule is necessary. \n\nRequest to Revise DC-9 Supplemental Inspection Document (SID) \n\n\tOne commenter requests that, prior to issuance of the final rule, the DC-9 SID be revised to incorporate the actions required by this proposed AD. The commenter states that such a revision will eliminate confusion between the DC-9 SID and the proposed 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 Revise Compliance Time for Low Frequency Eddy Current (LFEC) or X-ray Inspection \n\n\tOne commenter requests that the compliance time for the initial inspection (LFEC or x-ray) in paragraph (b) of the proposal be revised to correspond with those presently in the SID program -- within three years after the effective date of the AD, or prior to 53,140 landings, whichever occurs later. The commenter points out that such a revision would permit its fleet to be inspected during major scheduled maintenance checks, which would reduce the burden of line maintenance and the number of line airplanes out of service as a result of any findings. The commenter agrees that the repetitive inspection interval should remain at 3,225 landings, as specified in the proposed rule. \n\n\tThe FAA does not concur with the commenter's request to revise the compliance time for the initial inspection specified in paragraph (b) of the AD. The commenter provided no technical justification for revising this interval. Fatigue cracking of the fuselage skin and doubler at the corners of the forward service door doorjamb is a significant safety issue, and the FAA has determined that the inspection threshold, as proposed, is warranted, based on the effectiveness of the inspection procedure to detect fatigue cracking. The FAA considered not only those safety issues in developing an appropriate compliance time for this action, but the recommendations of the manufacturer, and the practical aspect of accomplishing the required inspection within an interval of time that parallels normal scheduled maintenance for the majority of affected operators. In light of these factors, the FAA has determined that the initial compliance time, as proposed, is appropriate. \n\nOther Relevant Rulemaking \n\n\tThe FAA has revised the final rule to include a new paragraph (f). This new paragraph states that accomplishment of the inspection requirements of this AD constitutes terminating action for inspections of Principal Structural Element (PSE) 53.09.033 (reference McDonnell Douglas Model DC-9 Supplemental Inspection Document) required by AD 96-13-03, amendment 39-9671 (61 FR 31009, June 19, 1996). Since this new paragraph is being added, the FAA has removed "NOTE 4," which is no longer necessary. \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 with the change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 64 McDonnell Douglas Model DC-9-31 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 51 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required one-time visual inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the one-time visual inspection required by this AD on U.S. operators is estimated to be $3,060, or $60 per airplane. \n\n\tThe cost impact figure discussed above is 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\n\tShould an operator be required to accomplish the LFEC or x-ray 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 any necessary LFEC or x-ray inspection is estimated to be $60 per airplane, per inspection cycle. \n\n\tShould an operator be required to accomplish the HFEC 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 any necessary HFEC inspection is estimated to be $60 per airplane, per inspection cycle. \n\n\tShould an operator be required to accomplish the modification, it would take approximately 30 work hours per airplane toaccomplish, at an average labor rate of $60 per work hour. Required parts would cost approximately $4,800 per airplane. Based on these figures, the cost impact of any necessary modification is estimated to be $6,600 per airplane. \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 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." \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 adding the following new airworthiness directive: