[Federal Register Volume 59, Number 143 (Wednesday, July 27, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-18226] [[Page Unknown]] [Federal Register: July 27, 1994] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-65-AD] Airworthiness Directives; McDonnell Douglas Model DC-8-70 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the supersedure of 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 action would require modification of the engine exhaust plug assemblies; when accomplished, this modification would terminate the need for the currently required replacement and check. This proposal 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 the proposed 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. DATES: Comments must be received by September 9, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-65-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule 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 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. FOR FURTHER INFORMATION CONTACT: Robert Baitoo, Aerospace Engineer, Propulsion Branch, ANM-141L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California 90806-2425; telephone (310) 988-5245; fax (310) 988- 5210. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 94-NM-65-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-65-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion On January 17, 1983, the FAA issued AD 83-02-05, amendment 39-4544 (48 FR 5539, February 7, 1983), applicable to all McDonnell Douglas Model DC-8-70 series airplanes, to require replacement of all attachment screws at the exhaust nozzle plug splice. That AD also requires a check of nut plates for running torque and replacement of nut plates not meeting the minimum run down torque of five inch-pounds. That action was prompted by reports of loose or missing attachment screws at the plug splice joint. In one reported incident, the exhaust plug nozzle separated from one engine while the airplane was in flight. The requirements of that AD are intended to prevent separation of the exhaust nozzle plug from the engine. Since the issuance of that AD, three operators have reported four incidents of loose or missing attachments at the splice joint of the engine forward and aft exhaust plugs. These discrepancies were found on airplanes subsequent to the accomplishment of AD 83-02-05. One operator reported loss of the rear exhaust plug on one airplane after the engine sustained a bird strike. Investigation revealed that the cause of these loose or missing splice joint attachments was attributed to higher temperatures and vibration effects of the engine exhaust. Operators also reported loose nuts at the forward plug-to-engine turbine flange attachments. The cause of these loose nuts has been attributed to high temperature and incompatibility of the nut threads with associated threaded studs. These conditions, if not corrected, could result in 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. The FAA has reviewed and approved McDonnell Douglas DC-8-70 Service Bulletin 78-112, Revision 2, dated March 8, 1994, that describes procedures for modification of the engine exhaust plug assemblies. The modification entails replacement of existing fasteners with permanent fasteners having larger diameters; this will serve to strengthen the splice installation and minimize the possibility of loose splice joint fasteners. Further, this modification entails replacement of existing nuts with nuts that are less susceptible to the effects of higher temperatures and have compatible thread pitch, which minimizes the possibility of forward plug-to-engine turbine attachments becoming loose. Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 83-02-05 to require modification of the engine exhaust plug assemblies. The actions would be required to be accomplished in accordance with the service bulletin described previously. Accomplishment of this modification would constitute terminating action for the currently required replacement and check. There 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 would be affected by this proposed AD, that it would take approximately 46 work hours per airplane to accomplish the proposed modification, and that the average labor rate is $55 per work hour. Required parts would cost approximately $21,400 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $1,866,540, or $23,930 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by removing amendment 39-4544 (48 FR 5539, February 7, 1983), and by adding a new airworthiness directive (AD), to read as follows: McDonnell Douglas: Docket 94-NM-65-AD. Supersedes AD 83-02-05, Amendment 39-4544. Applicability: All Model DC-8-70 series airplanes, certificated in any category. Compliance: Required as indicated, unless accomplished previously. 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, accomplish the following: (a) Within 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. (1) Replace all NAS560XK4-5 screws with NAS560XK4-4 screws at the exhaust nozzle plug splice. (2) Check nut plates for running torque and replace all nut plates not meeting the minimum run down torque of five inch-pounds. (b) Within 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. (c) An 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. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO. (d) Special flight permits may be issued in accordance with Secs. 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. Issued in Renton, Washington, on July 20, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-18226 Filed 7-26-94; 8:45 am] BILLING CODE 4910-13-U