AD 94-22-03 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, that requires modification of the power transfer unit (PTU). This amendment is prompted by reports of fatigue cracks found in the drain port housings of the PTU's on several airplanes. The actions specified by this AD are intended to prevent failure of the PTU housing due to fatigue cracking, which could result in the loss of both hydraulic systems (until the PTU is shut off).\n\n\tThe incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of November 28, 1994.

Final rule.

94-22-03 McDONNELL DOUGLAS: Amendment 39-9052. Docket 94-NM-78-AD. \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 Service Bulletin 29-53, Revision 1, dated April 21, 1994; excluding airplanes equipped with Vickers PV3-160 Engine Driven Pumps; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent loss of both hydraulic systems due to the failure of the housings of the power transfer unit (PTU), accomplish the following: \n\n\t(a)\tPrior to or upon the accumulation of 14,300 flight cycles on the PTU, or within 9 months after the effective date of this AD, whichever occurs later, modify the PTU assembly, part number 4100310, in accordance with McDonnell Douglas Service Bulletin 29-53, Revision 1, dated April 21, 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 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(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 modification shall be done in accordance with McDonnell Douglas Service Bulletin 29-53, Revision 1, dated April 21, 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, 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(e)\tThis amendment becomes effective on November 28, 1994.

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-9-80 series airplanes and Model MD-88 airplanes was published in the Federal Register on July 27, 1994 (59 FR 38146). That action proposed to require modification of the power transfer unit (PTU). \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 requested that the proposed compliance time of "14,300 flight cycles on the PTU or 9 months after the effective date of the AD, whichever occurs later," be extended. These commenters are concerned that they will be unable to modify their affected fleets within the proposed compliance time due to a possible problem in the availability of an ample number of required parts from the manufacturer. The FAA does not concur with the commenter's request to extend the compliance time. 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 installing the required modification within a maximum interval of time allowable for all affected airplanes to continue to operate without compromising safety. The FAA has been advised that an ample number of required parts will be available for modification of the U.S. fleet within the proposed compliance period. However, under the provisions of paragraph (b) of the final rule, the FAA will consider requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. \n\n\tThe applicability of the final rule has been revised to delete the reference toModel "DC-9-84 (MD-84)." This inclusion of this reference was in error; no such model of airplane exists. \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 1,074 Model DC-9-80 series airplanes and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 578 airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $2,912 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $1,752,496, or$3,032 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 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 airworthinessdirective:

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 Certification Office, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Walter Eierman, Systems and Equipment Branch, ANM-131L, FAA, Transport Airplane Directorate, Los Angeles ACO, 3229 East Spring Street, Long Beach, California 90806-2425; telephone (310) 988-5336; fax (310) 988-5210.