AD 94-22-07

This amendment supersedes an existing airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-8-70 series airplanes, that currently requires replacement of all attachment screws at the exhaust nozzle plug splice, and a check of nut plates for running torque and replacement of nut plates, if necessary. This amendment requires modification of the engine exhaust plug assemblies as terminating action for the currently required replacement and check. This amendment is prompted by reports of loose or missing attachments at the splice joint of the engine forward and aft exhaust plugs, and loss of the rear exhaust plug following an engine bird strike. The actions specified by this AD are intended to prevent reduced integrity of the engine exhaust plug installation, which may lead to separation of exhaust plugs from the airplane, and create a hazard to persons and property on the ground.

Final rule.

94-22-07 MCDONNELL DOUGLAS: Amendment 39-9056. Docket 94-NM-65-AD. Supersedes AD 83-02-05, Amendment 39-4544. \n\n\tApplicability: All Model DC-8-70 series airplanes, certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent reduced integrity of the engine exhaust plug installation, which may lead to separation of exhaust plugs from the airplane, and create a hazard to persons and property on the ground, accomplish the following: \n\n\t(a)\tWithin 300 flight hours after February 7, 1983 (the effective date of AD 83-02-05, amendment 39-4544), accomplish the procedures specified in paragraphs (a)(1) and (a)(2) of this AD in accordance with McDonnell Douglas DC-8-70 Alert Service Bulletin A78-107, dated November 30, 1982; McDonnell Douglas DC-8-70 Service Bulletin 78-107, dated January 16, 1984; or McDonnell Douglas DC-8-70 Service Bulletin 78-107, Revision 1, dated June 12, 1984. \n\n\t\t(1)\tReplace all NAS560XK4-5 screws with NAS560XK4-4 screws at the exhaust nozzle plug splice. \n\n\t\t(2)\tCheck nut plates for running torque and replace all nut plates not meeting the minimum run down torque of five inch-pounds. \n\n\t(b)\tWithin 24 months after the effective date of this AD, modify the engine exhaust plug assemblies in accordance with McDonnell Douglas DC-8-70 Service Bulletin 78-112, Revision 2, dated March 8, 1994. Accomplishment of this modification constitutes terminating action for the replacement and check requirements of paragraph (a) of this AD. \n\n\t(c)\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: 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(d)\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(e)\tThe modification shall be done in accordance with McDonnell Douglas DC-8-70 Service Bulletin 78-112, Revision 2, dated March 8, 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 FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California 90806-2425; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(f)\tThis amendment becomes effective on December 12, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 83-02-05, amendment 39-4544 (48 FR 5539, February 7, 1983), which is applicable to all McDonnell Douglas Model DC-8-70 series airplanes, was published in the Federal Register on July 27, 1994 (59 FR 38144). The action proposed to require replacement of all attachment screws at the exhaust nozzle plug splice, and a check of nut plates for running torque and replacement of nut plates, if necessary. The action also proposed to require modification of the engine exhaust plug assemblies; when accomplished, this modification would terminate the need for the currently required replacement and check. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the two comments received. \n\n\tOne commenter supports the proposed rule. \n\n\tOne commenter requests that the compliance time for the accomplishment of the modification be extended from the proposed 24 months to 60 months. This commenter states that it would have to procure additional spare engines and would need to special schedule its fleet of airplanes to accomplish this modification within the proposed compliance time. This would entail considerable expense over what was estimated in the FAA's cost impact analysis. The commenter indicates that a compliance time of 60 months would allow the modification to be accomplished during regularly scheduled maintenance, thereby eliminating any additional expenses. \n\n\tThe FAA does not concur. In developing an appropriate compliance time for this action, the FAA considered the safety implications, parts availability, and the practical aspect of installing the required modification during normal maintenance schedules. In light of this, the FAA does not consider it appropriate to change the compliance time for all operators based on the unique circumstances of anindividual operator. On the other hand, paragraph (c) of the AD provides that an individual may request an adjustment of compliance time that provides an acceptable level of safety, and this would be the appropriate means for the commenter to seek the requested relief. \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\n\tThere are approximately 110 Model DC-8-70 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 78 airplanes of U.S. registry will be affected by this AD, that it will take approximately 46 work hours per airplane to accomplish the required modification, and that the average labor rate is $55 per work hour. Required parts will cost approximately $21,400 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,866,540, or $23,930 per airplane. \n\n\tThe total 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\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), 1421and 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 removing amendment 39-4544 (48 FR 5539, February 7, 1983), and by adding a new airworthiness directive (AD), amendment 39-9056, to read as follows: