AD 95-02-14 ACTIVE

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 Model C-9 (military) airplanes, that requires replacement of the engine nose cowl attaching bolts and the installation of bearing plates on the nose cowl attach ring. This amendment is prompted by incidents in which the nose cowl separated from the airplane due to the elongation and/or breakout of the nose cowl's attachment ring holes, and failure of the attaching bolts. The actions specified by this AD are intended to prevent separation of the engine nose cowl from the airplane, which could result in damage to the airplane structure or could present a hazard to persons or property on the ground.

Final rule.

95-02-14 McDONNELL DOUGLAS: Amendment 39-9133. Docket 94-NM-144-AD. \n\n\tApplicability: Model DC-9-10, -20, -30, -40, and -50 series airplanes, and Model C-9 (military) airplanes; as listed in McDonnell Douglas DC-9 Alert Service Bulletin A71-63, dated July 21, 1994; 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 use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent separation of the engine nose cowl from the airplane, accomplish the following: \n\n\t(a)\tWithin 18 months after the effective date of this AD, replace the left and right engine nose cowl attaching bolts and install bearing plates, in accordance with McDonnell Douglas DC-9 Alert Service Bulletin A71-63, dated July 21, 1994; or Revision 1, dated December 15, 1994. \n\n\t(b)\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 MaintenanceInspector, 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(c)\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(d)\tThe replacement shall be done in accordance with McDonnell Douglas DC-9 Alert Service Bulletin A71-63, dated July 21, 1994; or McDonnell Douglas DC-9 Alert Service Bulletin A71-63, Revision 1, dated December 15, 1994. 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, P.O. Box 1771, Long Beach, California 90801-1771, Attention: Business Unit Manager, Technical Administrative Support, Dept. L51, M.C. 2-98. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 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(e)\tThis amendment becomes effective on March 17, 1995.

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 Model C-9 (military) airplanes, was published in the Federal Register on October 18, 1994 (59 FR 52483). That action proposed to require replacement of the engine nose cowl attaching bolts and the installation of bearing plates on the nose cowl attach ring. \n\nDiscussion of Comments \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\tTwo commenters request that the proposed compliance time of 12 months for replacement be extended so that the required action can be accomplished during regularly scheduled maintenance activities. One commenter suggests a compliance time of18 months; the other commenter suggest a compliance time of 3,000 hours time-in-service. The FAA concurs that the compliance time can be extended somewhat. In developing an appropriate compliance time for this action, the FAA considered not only the degree of urgency associated with addressing the subject unsafe condition, but the availability of required parts and the practical aspect of accomplishing the required replacement on the affected fleet in a timely manner. The FAA's intent was that the replacement be conducted during a regularly scheduled maintenance visit for the majority of the affected fleet, when the airplanes would be located at a base where special equipment and trained personnel would be readily available, if necessary. Based on the information supplied by the commenters, the FAA now recognizes that 18 months corresponds more closely to the interval representative of most of the affected operators' normal maintenance schedules. Paragraph (a) of the final rule has been revised to reflect a compliance time of 18 months. The FAA does not consider that this extension will adversely affect safety. \n\n\tOne commenter questions the FAA's estimate of the cost of required replacement parts. The commenter states that the $1,200 per airplane figure, presented in the cost impact information in the preamble to the notice, is too low. This commenter suggests that parts costs will be approximately $15,700 per airplane. Upon further review, the FAA concurs that the cost of required parts may be more than what was previously estimated. The manufacturer has provided updated cost figures for replacement bearing plates and bolts. If these items are purchased directly from the manufacturer, the cost of replacement bearing plates may be as much as $13,284 (36 plates at $369 each), and the cost of replacement bolts may be as much as $1,900 (38 bolts at $50 each). However, the FAA points out that bearing plates can be fabricated locally at a nominal cost, andbolts can be procured from the operator's current stock, thereby reducing parts costs considerably. The FAA has revised the cost impact information, below, to include this updated information on the cost of required parts. \n\nDiscussion of Additional Changes to the Rule \n\n\tSince issuance of the notice, the FAA has reviewed and approved Revision 1 to McDonnell Douglas DC-9 Service Bulletin A71-63, dated December 15, 1994. This revision is essentially identical to the originally issued service bulletin, which was referenced in the notice as the appropriate source of service information; however, it contains certain editorial revisions and additional nose cowl part numbers. The FAA has revised the final rule to include this revision of the service bulletin as an additional source of service information. \n\n\tAs a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been added to this final rule to clarify this requirement. \n\n\tAdditionally, the FAA has recently reviewed the figures it has used over the past several years in calculating the economic impact of AD activity. In order to account for various inflationary costs in the airline industry, the FAA has determined that it is necessary to increase the labor rate used in these calculations from $55 per work hour to $60 per work hour. The cost impact information, below, has been revised to reflect this increase in the specified hourly labor rate. \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 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. \n\nCost Impact \n\n\tThere are approximately 892 Model DC-9-10, -20, -30, -40, and -50 series airplanes, and Model C-9 (military) airplanes of the affected design in the worldwide fleet. The FAA estimates that 557 airplanes of U.S. registry will be affected by this AD. \n\n\tIt will take approximately 6 work hours per airplane to accomplish the required replacement actions, at an average labor rate of $60 per work hour. Required parts will vary in price, depending upon whether they are purchased from the manufacturer, manufactured locally, or procured from the operator's existing stocks. If all required parts (36 bearing plates and 38 bolts) are purchased from the manufacturer, the cost could be as much as $15,184 per airplane. However, if the bearing plates are manufactured locally and bolts are retrieved from the operator's current stock, the estimated costs will be considerably lower, approximately $1,900 per airplane. \n\n\tBased on these figures, the total cost impact of the AD on U.S. operators is estimated to be between $1,258,820 (or $2,260 per airplane) and $8,658,008 (or $15,544 per airplane). This total cost impact figure 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\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\n Adoption 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.\tThe authority citation for part 39 continues to read as follows: \n\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\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive:

The service information referenced in this AD may be obtained from McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, California 90801-1771, Attention: Business Unit Manager, Technical Administrative Support, Dept. L51, M.C. 2-98. 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, Los Angeles Aircraft\nCertification Office, Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Robert Baitoo, Aerospace Engineer, Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (310) 627-5245; fax (310) 627-5210.