AD 94-09-02

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, that currently requires an inspection to detect damage of the auxiliary power unit (APU) power feeder cable installation, repair of damaged cables, and modification of the cable installation. This amendment requires an inspection of previously modified airplanes to determine whether a spacer or "stand off" has been installed, and installation of those items, if necessary. This amendment is prompted by reports of generator power feeder cables electrically shorting to the airplane structure due to chafing. The actions specified by this AD are intended to prevent the APU power feeder cable from chafing against adjacent structures, which could result in electrical shorting and arcing, and a fire below the cabin floor.

Final rule.

94-09-02 McDONNELL DOUGLAS: Amendment 39-8890. Docket 93-NM-110-AD. Supersedes AD 88-20-05, Amendment 39-6022. \n\n\tApplicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) series airplanes, and Model MD-88 airplanes; as listed in McDonnell Douglas MD-80 Service Bulletin 24-94, Revision 1, dated May 28, 1987, and McDonnell Douglas Model MD-80 Service Bulletin 24-100, dated March 30, 1988; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent the APU power feeder cable from chafing against adjacent structures, which could result in electrical shorting and arcing, and a fire below the cabin floor, accomplish the following: \n\n\tNOTE 1: Paragraphs (a) and (b) of this AD merely restate the requirements of paragraphs (a) and (b) of AD 88-20-05, Amendment 39-6602. As allowed by the phrase, "unless accomplished previously," if those requirements of AD 88-20-05 have already been accomplished, this AD does not require that those actions be repeated. \n\n\t(a)\tFor airplanes listed in McDonnell Douglas MD-80 Service Bulletin 24-94, Revision 1, dated May 28, 1987: Within 12 months after October 31, 1988 (the effective date of AD 88-20-05, Amendment 39-6022), perform a visual inspection to detect damage of the auxiliary power unit (APU) power feeder cable support clamp installation; and prior to further flight, repair the damaged cable, and modify the APU power feeder cable installation; in accordance with McDonnell Douglas MD-80 Service Bulletin 24-94, Revision 1, dated May 28, 1987. \n\n\t(b)\tFor airplanes listed in McDonnell Douglas MD-80 Service Bulletin 24-100, dated March 30, 1988: Within 12 months after October 31, 1988 (the effective date of AD 88-20-05, Amendment 93-6022), modify the APU power feeder cable support clamp installation in accordance with McDonnell Douglas MD-80 Service Bulletin 24-100, dated March 30, 1988. \n\n\t(c)\tFor airplanes identified as Groups IV through IX in McDonnell Douglas Service Bulletin 24-94, Revision 4, dated June 7, 1993, on which the inspection and modification requirements of paragraphs (a) and (b) of this AD have been accomplished prior to the effective date of this AD, and which have not been inspected in accordance with McDonnell Douglas MD- 80 Service Bulletin 24-94, Revision 4, dated June 7, 1993: Within 12 months after the effective date of this AD, perform a general visual inspection of the APU power feeder cable support clamp installation to determine whether a spacer or "stand off" has been installed between the clamp and the bracket. \n\n\tNOTE 2: Accomplishment of the procedures specified in McDonnell Douglas Service Bulletin 24-105, dated August 15, 1989, is considered an acceptable alternative method of compliance with this paragraph. Operators who have accomplished those procedures prior to the effective date of this AD are not required to re-inspect the subject area. \n\n\t\t(1)\tIf a spacer or "stand off" has been installed, no further action is required by this AD. \n\n\t\t(2)\tIf a spacer or "stand off" has not been installed, prior to further flight, install a new or serviceable spacer or "stand off," part number (P/N) NAS43DD3-32, in accordance with McDonnell Douglas MD-80 Service Bulletin 24-94, Revision 4, dated June 7, 1993. \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 3: 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\tNOTE 4: Alternative methods of compliance approved for paragraphs (a) and (b) of AD 88-20-05, Amendment 39-6602, continue to be considered acceptable for this AD. \n\n\t(e)\tSpecial flight permits may be issued in accordance with Federal Aviation Regulations (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)\tThe installation shall be done in accordance with McDonnell Douglas MD-80 Service Bulletin 24-94, Revision 4, dated June 7, 1993. 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 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, 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 May 20, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations by superseding AD 88-20-05, amendment 39-6022 (53 FR 36436, September 20, 1988), which is applicable to McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, was published in the Federal Register on September 9, 1993 (58 FR 46917). The action proposed to continue to require a one-time visual inspection to detect damage of the APU power feeder cable support clamp installation, repair of damaged cables, and modification of the APU power feeder cable installation. The action proposed to add a general visual inspection of previously modified airplanes to determine whether a spacer or "stand off" has been installed between the clamp and the bracket, and installation of a spacer or "stand off," if necessary. \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\tOne commenter requests that the proposed rule provide "credit" for operators who have previously accomplished the procedures specified in McDonnell Douglas Service Bulletin 24-105, dated August 15, 1989. Those procedures ensure the installation of a "stand off" between the clamp and the bracket in the APU power feeder cable support clamp installation. Paragraph (c) of the proposal would require operators to inspect for the installation of this item; if it is installed, no further action would be required by the proposed AD. The FAA concurs. Paragraph (c) has been revised to indicate that McDonnell Douglas Service Bulletin 24-105 is considered an acceptable alternative method of compliance with that paragraph, and that operators who have accomplished the procedures described in that service bulletin are not required to re-inspect the subject area. \n\n\tThis same commenter requests that proposed paragraph (c) be revised to clarify the airplanesto which the requirements are applicable. The commenter points out that the referenced McDonnell Douglas Service Bulletin 24-94, Revision 4, dated June 7, 1993, specifies that the applicable airplanes are those listed as "Groups IV through IX" in that service bulletin, which have not been inspected in accordance with that service bulletin, but have been inspected and modified in accordance with paragraphs (a) and (b) of the existing AD. The FAA concurs that this clarification is appropriate. Therefore, paragraph (c) of the final rule has been revised accordingly. \n\n\tOne commenter notes that paragraph (c)(2) of the proposed AD calls out a specific spacer, part number NAS43DD3-32, that must be installed (under a clamp used to secure the APU generator feeders) in accordance with McDonnell Douglas Service Bulletin 24-94, Revision 4. The commenter points out that Table III (page 24) of that service bulletin refers to Service Rework Drawing SR09240004, sheet 7.7, for installation of the spacer; however, the revision of that drawing that the commenter has does not provide positive identification (i.e., no part number) of any spacer to be installed. The commenter requests that the FAA require that the service information correctly identify, on the installation drawing, the part number of the spacer that should be used. The FAA concurs. Since issuance of the notice, the FAA has reviewed and approved Revision G of the referenced drawing, which does call out the part number of the correct spacer that is to be used. No change to the final rule is necessary because of this, however. \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\n\tThere are approximately 390 Model DC-9 series airplanes and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 241 airplanes of U.S. registry will be affected by this AD, that it will take approximately 34 work hours per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $450,670, or $1,870 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\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me bythe Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations 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 removing amendment 39-6022 (53 FR 36436, September 20, 1988), and by adding a new airworthiness directive (AD), amendment 39-8890, to read as follows: