AD 97-03-05

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas DC-9 series airplanes, that currently requires repetitive visual inspections to detect corrosion and cracking of the fuselage upper skin and frames in the area of the loop antenna assemblies of the automatic direction finder (ADF), and repair, if necessary. This amendment adds a requirement to perform a visual and an eddy current inspection of the fuselage forward upper skin under the antennas, followed by the reinstallation of the ADF antennas using an improved procedure. This amendment is prompted by the development of a modification of the ADF antenna installation that constitutes terminating action for the required repetitive visual inspections. The actions specified by this AD are intended to prevent rapid decompression of the fuselage, significant structural damage, and subsequent reduced structural integrity of the airplane, due to problems associated with corrosion and fatigue cracking in the subject area.

Final rule.

97-03-05 MCDONNELL DOUGLAS: Amendment 39-9911. Docket 96-NM-235-AD. Supersedes AD 96-07-51, Amendment 39-9562. \n\n\tApplicability: Model DC-9 series airplanes having fuselage numbers 001 through 631 inclusive, 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 otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been otherwise 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 (d)(1) 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 prevent rapid decompression of the fuselage, significant structural damage, and subsequent reduced structural integrity of the airplane, due to problems associated with corrosion and fatigue cracking, accomplish the following: \n\n\t(a)\tWithin 15 days after April 15, 1996 (the effective date of AD 96-07-51, amendment 39-9562): Perform an internal visual inspection to detect corrosion and cracking of the fuselage forward upper skin and to detect cracking of the fuselage frame in the area of the forward and aft loop antenna assemblies of the automatic direction finder (ADF), in accordance with McDonnell Douglas Alert Service Bulletin DC9-53A282, dated March 20, 1996. \n\n\t\t(1)\tIf no corrosion or cracking is detected: Repeat the visual inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 6 months. \n\n\t\t(2)\tIf any corrosion or cracking is detected that is within thelimits specified in Chapter 53-04, Figure 29, of the DC-9 Structural Repair Manual (SRM): Prior to further flight, repair in accordance with Chapter 53-04, Figure 29, of the SRM. Thereafter, repeat the visual inspection required by paragraph (a) of this AD at intervals not to exceed 6 months. \n\n\t\t(3)\tIf any corrosion or cracking is detected in the fuselage forward upper skin, or if any cracking is detected in the fuselage frame, and that corrosion or cracking is outside the limits specified in Chapter 53-04, Figure 29, of the SRM: Prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\t(b)\tAt the applicable time specified in paragraph (b)(1) of (b)(2) of this AD, remove the ADF antennas and perform both a visual inspection and a high frequency eddy current inspection to detect corrosion and cracking of the fuselage forward upper skin under the antennas, in accordance with McDonnell Douglas Service Bulletin DC9-53-284, dated August 20, 1996. \n\n\t\t(1)\tFor airplanes on which the ADF antenna has not been previously removed and the fuselage skin has not been previously inspected for evidence of corrosion, within the last 4 years prior to the effective date of this AD: Accomplish the inspections within 2 years after the effective date of this AD. \n\n\t\t(2)\tFor airplanes on which the ADF antenna has been previously removed and the fuselage skin has been previously inspected for evidence of corrosion and/or repaired within the last 4 years prior to the effective date of this AD: Accomplish the inspections within 4 years after the effective date of this AD. \n\n\t(c)\tAs a result of the inspections required by paragraph (b) of this AD, accomplish the applicable action specified in paragraph (c)(1), (c)(2), or (c)(3) of this AD. Accomplishment of the actions specified in paragraph (c)(1) or (c)(2) constitutes terminating action for the requirements ofparagraphs (a)(1) and (a)(2) of this AD. \n\n\t\t(1)\tIf no cracking or corrosion is detected: Prior to further flight, reinstall the ADF antennas using the improved installation procedure in accordance with McDonnell Douglas Service Bulletin DC9-53-284, dated August 20, 1996. Thereafter, no further action is required by this AD. \n\n\t\t(2)\tIf any cracking or corrosion is detected that is within the limits specified in Chapter 53-04 of the DC-9 Structural Repair Manual (SRM): Prior to further flight, repair in accordance with Chapter 53-04 of the DC-9 SRM, and reinstall the ADF antennas using the improved installation procedure in accordance with McDonnell Douglas Service Bulletin DC9-53- 284, dated August 20, 1996. Thereafter, no further action is required by this AD. \n\n\t\t(3)\tIf any cracking or corrosion is detected that is outside the limits specified in Chapter 53-04 of the SRM: Prior to further flight, repair in accordance with a method approved by the Manager, Los Angeles Certification Office (ACO), FAA, Transport Airport Directorate. \n\n\t(d)\t(1)\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 2: 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\t(2)\tAlternative methods of compliance, approved in accordance with AD 96-07-51, amendment 39-9562, are approved as alternative methods of compliance with this AD. \n\n\t(e)\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 alocation where the requirements of this AD can be accomplished. \n\n\t(f)\tThe actions shall be done in accordance with McDonnell Douglas Alert Service Bulletin DC9-53A282, dated March 20, 1996; and McDonnell Douglas Service Bulletin DC9-53- 284, dated August 20, 1996. The incorporation by reference of the former service bulletin was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of April 15, 1996 (61 FR 15882, April 10, 1996). The incorporation by reference of the latter service bulletin 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(g)\tThis amendment becomes effective on March 10, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 96-07-51, amendment 39-9562 (61 FR 15882, April 10, 1996), which is applicable to certain McDonnell Douglas DC-9 series airplanes, was published in the Federal Register on October 23, 1996 (61 FR 54969). That action proposed to continue to require repetitive internal visual inspections to detect corrosion and cracking of the fuselage forward upper skin and to detect cracking of the fuselage frame in the area of the forward and aft loop antenna assemblies of the automatic direction finder (ADF), as is currently required by AD 97-07-01. However, it also proposed to add a requirement to perform a visual and an eddy current inspection of the fuselage forward upper skin under the antennas, followed by the reinstallation of the ADF antennas using an improved procedure. Accomplishment of these actions would constitute terminating action for the required repetitiveinspections. \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\nSupport for the Proposal \n\n\tFive commenters support the proposed AD. \n\nRequest to Extend Compliance Time for Certain Airplanes \n\n\tOne commenter supports the intent of the proposal, but requests that the compliance time for accomplishing the terminating action be extended from the proposed 24 months to 48 months for those airplanes on which the antenna has been reinstalled within the past 4 years. The commenter notes that the compliance schedule for the terminating action does not address the condition where the ADF antenna was previously removed and the fuselage skin inspection and repaired, i.e., in accordance with the previously issued AD 96-07-51. The commenter considers that, for the repaired airplanes, a higher level of safety has been achieved than if no such repair had been performed. Considering the number of airplanes that are affected by this AD (approximately 403), allowing an extension of the time for installing the final fix on the previously repaired airplanes also will minimize the operational impact of the AD on operators. \n\n\tThe FAA concurs with the commenter's request. The FAA acknowledges that AD 96-07-51 (as well as this new AD) requires that, if any cracking or corrosion is found and it is within certain limits, the area must be repaired in accordance with either the Structural Repair Manual (SRM) or a manner approved by the FAA. In consideration of the increased structural integrity of the area that is provided by such repairs, the FAA finds that the risk of additional cracking is reduced and accomplishment of the terminating action may be extended for an additional 2 years (for a total of 4 years) without adversely affecting safety. Paragraph (b) of the final rule has been revised accordingly. \n\nConclusion \n\n\tAfter careful review of the availabledata, 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 569 McDonnell Douglas Model DC-9 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 403 airplanes of U.S. registry will be affected by this proposed AD. \n\n\tThe inspections that were previously required by AD 96-07-51 and retained in this new AD take approximately 5 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $120,900, or $300 per airplane, per inspection. \n\n\tThe terminating action that is required by this new AD will take approximately 16 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the new requirements of this AD on U.S. operators is estimated to be $386,880, or $960 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 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: \n\nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-9562 (61 FR 15882, April 10, 1996), and by adding a new airworthiness directive (AD), amendment 39-9911, to read as follows: