[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: 94-18279] [[Page Unknown]] [Federal Register: July 27, 1994] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-78-AD] Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series Airplanes and Model MD-88 Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes. This proposal would require modification of the power transfer unit (PTU). This proposal is prompted by reports of fatigue cracks found in the drain port housings of the PTU's on several airplanes. The actions specified by the proposed 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). 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-78-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, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 3229 East Spring Street, Long Beach, California. FOR FURTHER INFORMATION CONTACT: 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. 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-78-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-78-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The FAA has received reports of cracked drain port housings found on the power transfer units (PTU) installed on five McDonnell Douglas Model DC-9-80 series airplanes. In one incident, failure of the housing resulted in the loss of both hydraulic systems, which caused the airplane to depart from the runway during taxi due to the loss of braking and nose landing gear steering. Investigation has revealed that the cause of the cracking is attributed to fatigue. Further analysis of the hardware has indicated that the center housing and drain port housing can crack before the design life of the PTU has been reached. This condition, if not corrected, could lead to the failure of the housings associated with the PTU, which in turn could result in the loss of both hydraulic systems (until the PTU is shut off). The FAA has reviewed and approved McDonnell Douglas Service Bulletin 29-53, Revision 1, dated April 21, 1994, that describes procedures for modification of the center housing and drain port housing of the PTU. This modification entails replacing the currently installed cast aluminum housings with wrought aluminum housings, and reidentifying the part number of the PTU. Such modification will ensure that the housings meet the PTU design life requirements. (Note: This service bulletin references Allied Signal Service Bulletin 4100310-29-0031, Revision 3, dated April 8, 1994, for detailed modification instructions.) 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 require modification of the center housing and drain port housing of the PTU. The actions would be required to be accomplished in accordance with the McDonnell Douglas service bulletin described previously. This proposed AD would not be applicable to airplanes that are equipped with Vickers PV3-160 engine driven pumps. The FAA finds that this type of pump provides a pressurized flow of 21 gallons per minute and, in the event of a PTU crack or failure, that rate of flow would be adequate to continue pressurizing the affected hydraulic system. There 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 would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Required parts would cost approximately $2,912 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $1,746,716, or $3,022 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 adding the following new airworthiness directive: McDonnell Douglas: Docket 94-NM-78-AD. Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-84 (MD-84), 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. Compliance: Required as indicated, unless accomplished previously. To prevent loss of both hydraulic systems due to the failure of the housings of the power transfer unit (PTU), accomplish the following: (a) Prior 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. (b) 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. (c) Special flight permits may be issued in accordance with Sec. Sec. 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. 94-18279 Filed 7-26-94; 8:45 am] BILLING CODE 4910-13-U