AD 94-03-01

This amendment supersedes an existing airworthiness directive (AD), applicable to McDonnell Douglas Model DC-9 series airplanes and C-9 (military) airplanes, that currently requires the implementation of a program of structural inspections to detect and correct fatigue cracking in order to ensure the continued airworthiness of these airplanes as they approach the manufacturer's original fatigue design life goal. This amendment requires, among other things, revision of the existing program to require visual inspections of additional structure. This amendment is prompted by new data submitted by the manufacturer indicating that certain revisions to the program are necessary in order to increase the confidence level of the statistical program to ensure timely detection of cracks in various airplane structures. The actions specified by this AD are intended to prevent fatigue cracking that could compromise the structural integrity of these airplanes.

Final rule.

94-03-01 McDONNELL DOUGLAS: Amendment 39-8807. Docket 93-NM-08-AD. Supersedes AD 87-14-07 R1, Amendment 39-6019.\n\n\tApplicability: Model DC-9-10, -20, -30, -40, -50 series airplanes, and C-9 (Military) airplanes; certificated in any category.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo ensure the continuing structural integrity of these airplanes, accomplish the following:\n\n\t(a)\tWithin one year after December 23, 1988 (the effective date of AD 87-14-07 R1, Amendment 39-6019), incorporate a revision into the FAA-approved maintenance inspection program which provides for inspection(s) of the Principal Structural Elements (PSE) defined in McDonnell Douglas Report No. L26-008, "DC-9 Supplemental Inspection Document (SID)," Section 2 of Volume I (All Series) of Revision 1, dated November 1987, in accordance with Section 2 of Volume III-87, dated November 1987, of the SID. The non-destructive inspection (NDI) techniques set forth in Section 2 ofVolume II, dated November 1987, of the SID provide acceptable methods for accomplishing the inspections required by this paragraph. All inspection results (negative or positive) must be reported to McDonnell Douglas, in accordance with the instructions contained in Section 2 of Volume III-87, dated November 1987, of the SID. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.\n\n\tNOTE 1: Volume II, dated November 1987, of the SID is comprised of the following:\n\n\nVolume Designation\nRevision Level Shown on Volume\nVolume II-10/20\nOriginal\nVolume II-20/30\n1\nVolume II-40\nOriginal\nVolume II-50\nOriginal\n\n\t\t(b)\tWithin 6 months after the effective date of this AD, replace the revision of the FAA-approved maintenance inspection program required by paragraph (a) of this AD, with a revision that provides for inspection(s) of the PSE's defined in McDonnell Douglas Report No. L26-008, "DC-9 Supplemental Inspection Document (SID)," Section 2 of Volume I of Revision 3, dated April 1991, in accordance with Section 2 of Volume III-92, dated July 1992, of the SID.\n\n\t\t(1)\tVisual inspections of all PSE's on airplanes listed in Volume III-92, dated July 1992, of the SID planning data, are required by the fleet leader-operator sampling (FLOS) program at least once during the interval between the start date (SDATE) and the end date (EDATE) established for each PSE. These visual inspections are defined in Section 3 of Volume II, dated April 1991, of the SID, and are required only for those airplanes that have not been inspected previously in accordance with Section 2 of Volume II, dated April 1991, of the SID.\n\n\t\t(2)\tThe NDI techniques set forth in Section 2 of Volume II, dated April 1991, of the SID provide acceptable methods for accomplishing the inspections required by this paragraph.\n\n\t\t(3)\tAll inspection results (negative or positive) must be reported to McDonnell Douglas, in accordance with the instructions contained in Section 2 of Volume III-92, dated July 1992, of the SID. Information collection requirements contained in this regulation have been approved by the OMB under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.\n\t\n\tNOTE 2: Volume II, dated April 1991, of the SID is comprised of the following:\n\n\nVolume Designation\nRevision Level Shown on Volume\nVolume II-10/20\n3\nVolume II-20/30\n4\nVolume II-40\n3\nVolume II-50\n3\n\n\tNOTE 3: NDI inspections accomplished in accordance with the following Volume II of the SID provide acceptable methods for accomplishing the inspections required by this paragraph:\n\n\nVolume Designation\nRevision Level\nDate of Revision\nVolume II-10/20\n3\nApril 1991\nVolume II-10/20\n2\nApril 1990\nVolume II-10/20\n1\nJune 1989\nVolume II-10/20\nOriginal\nNovember 1987\n\n\n\nVolume II-20/30\n4\nApril 1991\nVolume II-20/30\n3\nApril 1990\nVolume II-20/30\n2\nJune 1989\nVolume II-20/30\n1\nNovember 1987\n\n\n\nVolume II-40\n3\nApril 1991\nVolume II-40\n2\nApril 1990\nVolume II-40\n1\nJune 1989\nVolume II-40\nOriginal\nNovember 1987\n\n\n\nVolume II-50\n3\nApril 1991\nVolume II-50\n2\nApril 1990\nVolume II-50\n1\nJune 1989\nVolume II-50\nOriginal\nNovember 1987\n\n\t(c)\tAny cracked structure detected during the inspections required by paragraph (a) or (b) of this AD must be repaired before further flight, in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.\n\n\tNOTE 4: Requests for approval of any PSE repair that would affect the FAA-approved maintenance inspection program that is required by this AD should include a damage tolerance assessment for that PSE.\n\n\t(d)\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, 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 5: 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(e)\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.\n\n\t(f)\tCertain of the inspections to be added to the FAA-approved maintenance program shall be done in accordance with McDonnell Douglas Report No. L26-008, "DC-9 Supplemental Inspection Document (SID)," dated November 1987. The incorporation by reference of this document 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 December 23, 1988 (53 FR 46866, November 21, 1988). Certain other of the inspections to be added to the FAA-approved maintenance program shall be done in accordance with the following volumes of McDonnell Douglas Report No. L26-008, "DC-9 Supplemental Inspection Document (SID)," that contain the lists of effective pages indicated below:\n\n\t\t\t\n\nDocument\nPage Number\nRevision Level\nDate\nVolume I-\nAll Series\nList of Effective Pages\nA, B, C\n\n3\n\nApril 1991\nVolume II-10/20\nList of Effective Pages\nA, B, C, D, E, F, G, H,\nI, J, K \n\nL\n\n\n3\n\n2\n\n\nApril 1991\n\nApril 1990\nVolume II-20/30\nList of Effective Pages\nA, B, C, D, E, F, G, H,\nI, J, K, L, M, N, O, P,\nQ, R, S, U\t\n\nT\n\n\n\n4\n\nOriginal\n\n\n\nApril 1991\n\nApril 1990\nVolume II-40\nList of Effective Pages\nA, B, C, D, E, F, G, H,\nI, J, K, L, M, N, O\t\n\n\n3\n\n\nApril 1991\nVolume II-50\nList of Effective Pages\nA, B, C, D, E, F, G, H,\nI, J, K, L, M, N, O\t\n\n\n3\n\n\nApril 1991\nVolume III-92\nAll Series \nEntire Document\nOriginal\nJuly 1992\n\nThis 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, P.O. Box 1771, Long Beach, California 90846-1771, Attention: Business Unit Manager, Technical Publications - Technical Administrative Support, C1-L5B. 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, 3229 East Spring Street, Long Beach, 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 14, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations by superseding AD 87-14-07 R1, Amendment 39-6019 (53 FR 46866, November 21, 1988), which is applicable to McDonnell Douglas Model DC-9 series airplanes and C-9 (military) airplanes, was published in the Federal Register on March 29, 1993 (58 FR 16505). The action proposed to require, among other things, revision of the existing Structural Inspection Document (SID) sampling program to require additional visual inspections of all Principal Structural Elements (PSE) on certain airplanes.\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\n\tOne commenter supports the proposal.\n\n\tSeveral commenters objected to the proposed repair requirements which would require that any cracked structure detected during the required inspections be repaired "in accordance with a method approved by the Manager of the Los Angeles Aircraft Certification Office (LAACO)." These commenters prefer the language of AD 87-14-07 R1, which permitted cracked structure to be repaired "in accordance with an FAA-approved method," and request that the rule be revised to include this language. This requested language would allow repairs to be approved routinely by the manufacturer, Designated Engineering Representatives (DER), or SFAR 36-authorized organizations, without prior approval by the Manager of LAACO. The commenters' justification for this request involves three points:\n\n\t1.\tThe commenters contend that it is not logical that the manner of repair approval should differ between repairs of PSE's found cracked during a SID inspection and repairs of PSE's found cracked during inspections other that those directly called for by the SID program.\n\n\t2.\tThe commenters also contend that it should not be necessary to involve the Manager of the LAACO in the repair approval process, since the process takes too much time. The commenters consider that adequate repair procedures already are available in the DC-9 Structural Repair Manual (SRM) and the service bulletins referenced in the SID; repair procedures can also be designed and approved by DER's without further review and approval of the LAACO.\n\n\t3.\tSeveral of the commenters also request that the airplane manufacturer, operator DER's, and SFAR 36-authorized operators be allowed to approve repairs that are outside the scope of the SRM, at least temporarily, in order to allow the airplane to be returned to revenue service pending the outcome of a subsequent damage tolerance assessment (DTA) of the repair, which is required by the SID program of all repairs. These commenters state that restricting approval of such repairs to the LAACO Manager would hamper repair efforts and "would have an appreciable effect on the airplane's return-to-service times."\n\n\tThe FAA does not concur with the commenters' requests. While it is true that DER's and SFAR 36-authorized organizations are authorized to approve certain repairs of cracking that is found during routine maintenance or opportunity inspections, the FAA considers that any cracking detected in PSE structure during an inspection required by this AD (and the SID program) is indication of an airworthiness concern of a complex nature. Such cracking does not warrant "routine" handling, but requires expeditious action and a special approach to address it. It is crucial that the FAA be aware of all repairs made to PSE's or to their configuration. Where repair data do not exist, it is essential that the FAA have feedback as to the type of repairs being made. Given that possible new relevant issues might be revealed during this process, it is imperative that the FAA have such feedback. Only by reviewing repair approvals can the FAA be assured of this feedback and of the adequacy of the repair methods. The FAA has determined that standardization and continuityof repair approvals can best be maintained by having one single point of approval for all repairs of cracks in PSE's identified during SID inspections required by this AD. Since the Manager of the LAACO is accountable for the primary oversight for the actions regarding this AD, it is appropriate that he be this single point of approval. His involvement, therefore, is warranted in the development and approval of repairs.\n\n\tStandardization and continuity of repair approval is especially important in light of the complexity of the DC-9 SID program. This program is unique in that it is based on the principle of statistical sampling, which requires cooperation between aircraft operators, the manufacturer, and the FAA in selecting airplane samples, accomplishing inspections, reporting discrepancies as they are found, and evaluating the safety impact of the discrepancies so that timely program adjustments can be made and the appropriate corrective actions taken to protect both the discrepant airplane and the fleet. For example, when one bona fide fatigue crack is determined, the inspection and repair requirements must be developed in a timely manner to protect the entire Model DC-9 fleet. This requires coordination with the Manager of the LAACO for the review of all SID findings and a timely determination of bona fide fatigue cracking.\n\n\tFurther, cracked PSE structure detected during an inspection that is not directly required by the SID must first be reported to the FAA by the operator via a Service Difficulty Report (SDR), as is required by the relevant operating rules of the Federal Aviation Regulations. These SDR reports are compiled in an SDR data base that is used by the FAA for trend analysis and data studies used in planning, directing, controlling, and evaluating various airworthiness programs. Cracked PSE structure found during an inspection called out by the SID program (and this AD) are compiled into a SID data base that is used by the FAA for many of the same purposes as SDR data base, including identification of necessary revisions to the SID program itself. The Manager of the LAACO has access to both the SDR and the SID data bases and, therefore, he is in a unique position that affords him a broad overview both to understand and assess the overall cracking and repair environment, and to implement timely initiatives to address and manage it.\n\n\tAs part of the SID program, every repair of PSE structure is required to have a DTA in order to establish its effect on the fatigue life of the affected PSE structure. The DTA process involves the review and use of type design data that are proprietary and may not be available to those persons (such as a DER) who are generally authorized to approve routine repairs. For this reason, it is appropriate that the Manager of the LAACO be the focal point in the DTA approval process.\n\n\tIn some cases, repairs are made to PSE structure as a result of cracking that was found during an opportunity inspection, and the approval of the repair is made without the coordination of the manufacturer and the LAACO. When the time arrives for that PSE to be inspected in compliance with the AD, the PSE becomes a "discrepant PSE." If a DTA were not accomplished on the "discrepant PSE" at the time of the repair, compliance with the AD could require that the repair be removed or modified at a later time. In either case, the Manager of the LAACO is tasked to ensure that all repairs to cracked PSE's comply with the AD.\n\n\tThe FAA considers that any repair to cracked PSE's without the required DTA can only be temporary, and will eventually require coordination with the Manager of the LAACO. Most methods of repair specified in the DC-9 Structural Repair Manual, the relevant service bulletins, or DER-designed repairs do not include a continuing inspection program to ensure that the repair is inspected at the same level of safety as the original PSE structure. A DTA can be done most easilyat the time of repair, rather than at a later date when the details of the repair may be hard to obtain and, undoubtedly, would be more costly. Currently, the Manager and staff of the LAACO are working very closely with the manufacturer to expedite interim repair approval requests. Such requests may be made under the provisions of paragraph (d) of the final rule.\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\n\tThere are approximately 920 Model DC-9 series airplanes and C-9 (military) airplanes of the affected design in the worldwide fleet. The FAA estimates that 586 airplanes of U.S. registry and 19 U.S. operators would be affected by this proposed AD.\n\n\tIncorporation of the SID program into an operator's maintenance program, as was required by AD 87-14-07 R1, necessitates approximately 1,000 work hours (per operator), at an averagelabor cost of $55 per work hour. Based on these figures, the cost to the 19 affected U.S. operators to incorporate the SID program, which was required previously in accordance with AD 87-14-07 R1, is estimated to be $1,045,000.\n\n\tThe incorporation of the additional procedures that are required by this new AD action will require approximately 62 additional work hours per operator to accomplish, at an average labor cost of $55 per work hour. Based on these figures, the cost to the 19 affected U.S. operators to incorporate these additional procedures into the SID program into an operator's maintenance program is estimated to be $64,790.\n\n\tThe recurring inspection costs, as was required by AD 87-14-07 R1 and continues to be required by this new AD action, is approximately 341 work hours per airplane per year, at an average labor cost of $55 per work hour. Based on these figures, these recurring inspection costs are estimated to be $18,755 per airplane, or $10,990,430 for the affected U.S. fleet.\n\n\tThe recurring inspection procedures that are added to the program by this new AD action will require approximately 21 additional work hours per airplane per year to accomplish, at an average labor charge of $55 per work hour. Based on these figures, the additional recurring inspection cost impact added by this AD on U.S. operators is estimated to be $1,155 per airplane, or $676,830 for the affected U.S. fleet.\n\n\tBased on the figures discussed above, the total cost impact of this AD is estimated to be $11,732,050 for the first year, and $11,667,260 for each year thereafter. These "total cost impact" figures assume that no operator has yet accomplished any of the requirements of this AD. However, it can be reasonably assumed that a majority of affected operators have already initiated the original SID program (as required by AD 87-14-07 R1) and many may have already initiated the additional inspections required by this new AD action.\n\n\tAdditionally, the number ofrequired work hours for each inspection requirement of this AD (and the SID program), as indicated above, is presented as if the accomplishment of those actions were to be conducted as "stand alone" actions. However, in actual practice, these actions for the most part will be accomplished coincidentally or in combination with normally scheduled airplane inspections and other maintenance program tasks. Therefore, the actual number of necessary additional work hours will be minimal in many instances. Further, any costs associated with special airplane scheduling can be expected to be minimal.\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\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulationsas follows:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\t1.\tThe authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.\n\n§ 39.13 - (Amended)\n\t2.\tSection 39.13 is amended by removing amendment 39-6019 (53 FR 46866, November 21, 1988), and by adding a new airworthiness directive (AD), amendment 39-8807, to read as follows: