AD 95-12-25

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes. This amendment requires an inspection to detect chafing on the FIREX pipe assembly of the number one engine; and either repair of chafed pipe assemblies or replacement of the chafed pipe assemblies with new pipe assemblies; and modification of the FIREX and the pneumatic sense pipe assembly clamp marriage. This amendment is prompted by reports of incidents in which the pneumatic sense pipe chafed against the FIREX supply pipe of the number one engine. The actions specified by this AD are intended to prevent the chafing of the FIREX supply pipe, which could result in a hole in the pipe and subsequently prevent the proper distribution of the fire extinguishing agent within the nacelle in the event of a fire.

Final rule.

95-12-25 MCDONNELL DOUGLAS: Amendment 39-9278. Docket 94-NM-181-AD.\n\n\tApplicability: Model DC-9-10, -20, -30, -40, and -50 series airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) series airplanes; Model MD-88 airplanes; and Model C-9 (Military) series airplanes; as listed in McDonnell Douglas DC-9 Service Bulletin 26-25, Revision 2, dated April 18, 1995; certificated in any category.\n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (b) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo prevent the chafing of a hole in the FIREX supply pipe of the number one engine, which could prevent the proper distribution of the fire extinguishing agent within the nacelle in the event of a fire, accomplish the following:\n\n\t(a)\tWithin 8 months after the effective date of this AD, perform an inspection to detect chafing of the FIREX pipe assembly of the number one engine, in accordance with McDonnell Douglas DC-9 Service Bulletin 26-25, Revision 1, dated September 30, 1994, or Revision 2, dated April 18, 1995.\n\n\t\t(1)\tIf any chafing is detected, prior to furtherflight, accomplish paragraph (a)(1) and (a)(2) of this AD in accordance with the service bulletin. Where there are differences between the requirements of this AD and the procedures specified in the service bulletin, the AD prevails.\n\n\t\t\t(i)\tEither repair chafed pipe assemblies or replace the chafed pipe assemblies with new or serviceable pipe assemblies. And\n\n\t\t\t(ii)\tModify the FIREX and the pneumatic sense pipe assembly clamp marriage.\n\n\t\t(2)\tIf no chafing is detected, prior to further flight, modify the FIREX and the pneumatic sense pipe assembly clamp marriage in accordance with the service bulletin.\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 thensend it to the Manager, Los Angeles ACO.\n\n\tNOTE 2: 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 inspection, replacement, modification, and repair shall be done in accordance with McDonnell Douglas DC-9 Service Bulletin 26-25, Revision 1, dated September 30, 1994, or McDonnell Douglas DC-9 Service Bulletin 26-25, Revision 2, dated April 18, 1995. 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, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, 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 July 24, 1995.

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, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes was published in the Federal Register on December 8, 1994 (59 FR 63275). That action proposed to require inspection to detect chafing on the FIREX pipe assembly of the number one engine; and either replacement of the chafed pipe assemblies with new pipe assemblies and modification of the FIREX and the pneumatic sense pipe assembly clamp marriage, or repair of the chafed pipe assemblies.\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 proposed rule.\n\n\tTwo commenters request that the compliance time for accomplishment of the inspection be extended from the proposed 8 months to 12 months. This will allow the inspection to be accomplished during the time of a regularly scheduled "C" check. One commenter considers that adoption of the proposed compliance time of 8 months would result in an additional expense to operators to schedule special times for the accomplishment of this inspection. The FAA does not concur with the commenters' request to extend the compliance time for the inspection requirements. In developing an appropriate compliance time for this action, the FAA considered the safety implications, parts availability, and normal maintenance schedules for timely accomplishment of the inspection. In consideration of these items, as well as the several reports of chafing of the FIREX supply pipe assembly found on in-service airplanes, the FAA has determined that 8 months represents the maximum interval of time allowable wherein the inspection can reasonably be accomplished and an acceptable level of safety can be maintained. However,paragraph (b) of the final rule does provide affected operators the opportunity to apply for an adjustment of the compliance time if data are presented to justify such an adjustment.\n\n\tOne commenter states that paragraph (a)(1) of the proposed rule seems to offer an option of not modifying the clamping configuration if repair is needed. The commenter requests that paragraph (a)(1) be changed to read, ". . . either replace the chafed pipe assemblies with new pipe assemblies or repair chafed pipe assemblies; and modify the FIREX . . ." for clarification purposes. The FAA concurs. Further review of McDonnell Douglas Service Bulletin 26-25, which is referenced in the final rule as the appropriate source of service information, indicates that the repair procedures (described in paragraph 2.C.(2) of the service bulletin) include modification of the clamping configuration. Therefore, the modification is part of the repair, and is not optional. The FAA has revised paragraph (a)(1) of the final rule to clarify this modification requirement accordingly. Since this revision just clarifies a requirement of the rule, the FAA finds that it does not pose an increased burden on any operator.\n\n\tOne commenter requests that Model DC-9 series airplanes that are not equipped with a ventral stair be excluded from the applicability of the proposed rule. The commenter states that these airplanes do not have a pipe assembly having part number P/N 7914299-521 or 7914299-524; these pipe assemblies are referenced in Revision 1 of the service bulletin that is cited in the proposal as the appropriate source of service information. The FAA concurs. Since issuance of the proposal, the FAA has reviewed and approved Revision 2 of McDonnell Douglas DC-9 Service Bulletin 26-25, dated April 18, 1995. The procedures described in Revision 2 are identical to those described in Revision 1, but include minor editorial changes. However, Revision 2 revises the effectivity listing of the service bulletin by removing 544 non-ventral stair Model DC-9 series airplanes. Accordingly, the applicability of the final rule has been revised to include only those airplanes listed in Revision 2 of the service bulletin. Additionally, the economic impact information, below, has been revised to reduce the total cost impact by the amount of costs applicable to the 544 airplanes that have been deleted from the applicability of the final rule. Further, the final rule has been revised to reference Revision 2 of the service bulletin as an additional source of service information.\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 1,410 Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 553 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. The cost of required parts will be nominal. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $33,180, or $60 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\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment\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\t1.\tThe authority citation for part 39 continues to read as follows:\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\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: