AD 95-08-09 SUPERSEDED

This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes. This action requires modification of the support structure of the cargo liner. This amendment is prompted by a report of chafing and arcing in the vacuum waste exhaust heater that caused a spark to ignite the surrounding insulation blankets. The actions specified in this AD are intended to prevent fire and/or smoke due to chafing and arcing of the vacuum waste exhaust port heater.

Final rule; request for comments.

95-08-09 MCDONNELL DOUGLAS: Amendment 39-9198. Docket 95-NM-44-AD.\n\n\tApplicability: Model MD-11 series airplanes, as listed in McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 1995, and identified as "Group 1 airplanes," on which split heater cuffs have been installed on the waste exhaust ducts of heaters in accordance with McDonnell Douglas MD-11 Service Bulletin 38-15, dated October 23, 1992; 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 (c) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafecondition; 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 a fire and/or smoke due to chafing and arcing of the heater, accomplish the following:\n\n\t(a)\tWithin 30 days after the effective date of this AD, modify the support structure of the cargo liner, in accordance with McDonnell Douglas MD-11 Alert Service Bulletin MD11-38A044, dated March 22, 1995.\n\n\t(b)\tAs of the effective date of this AD, the support structure of the cargo liner on any airplane must be modified in accordance with McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22 1995, prior to installing a vacuum waste exhaust port heater, P/N 62-5745, in accordance with McDonnell Douglas MD-11 Service Bulletin 38-15, dated October 23, 1992.\n\n\t(c)\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 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(d)\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(e)\tThe modification shall be done in accordance withMcDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 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 FAA, 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(f)\tThis amendment becomes effective on May 2, 1995.

Recently, an operator of McDonnell Douglas Model MD-11 series airplanes reported that chafing and arcing in the vacuum waste exhaust heater caused a spark to ignite the surrounding insulation blankets. Investigation revealed that the cutout in the baffle for the vacuum waste exhaust duct rubbed against the heater tape, which caused the heater tape to chafe. (Split heater cuffs were installed on the vacuum waste exhaust ducts of these airplanes in accordance with McDonnell Douglas Service Bulletin 38-15, dated October 23, 1992.) This condition, if not corrected, could result in undetected fire and/or smoke due to chafing and arcing of the vacuum waste exhaust port heater.\n\n\tThe FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 1995, which describes procedures for modification of the support structure of the cargo liner. This modification entails removing the baffle assemblies and trimming the insulationblankets surrounding the vacuum waste exhaust duct, which will reduce chafing and minimize the possibility of igniting the insulation blanket.\n\n\tThe alert service bulletin includes two groups of airplanes in its effectivity listing: Airplanes identified as "Group 1" are equipped with split heater cuffs that were installed, after delivery, on the vacuum waste exhaust ducts of the heaters of these airplanes in accordance with McDonnell Douglas Service Bulletin 38-15, dated October 23, 1992. Airplanes identified as "Group 2" are those on which the manufacturer accomplished a similar modification prior to delivery.\n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent fire and/or smoke due to chafing and arcing of the heater. This AD requires modification of the support structure of the cargo liner of airplanes identified in the alert service bulletin as Group 1 airplanes. The actions are required to be accomplished in accordance with the alert service bulletin described previously.\n\n\tAlthough all of the airplanes identified in the effectivity listing of the referenced alert service bulletin have had split heater cuffs installed on the vacuum waste exhaust ducts, those identified as Group 1 airplanes differ significantly from those identified as Group 2 airplanes: Group 1 airplanes have had split heater cuffs installed on the vacuum waste exhaust ducts, in accordance with McDonnell Douglas Service Bulletin 38-15, dated October 23, 1992; that service bulletin did not adequately specify the minimum distance between the baffle assemblies the vacuum waste exhaust duct. Group 2 airplanes have had split heater cuffs installed during production using production drawings that adequately specified the minimum distance between the baffle assemblies and the vacuum waste exhaust duct. Consequently, because of the configuration of this installation, the FAA findsthat the potential for chafing and arcing to occur on Group 1 airplanes is much greater. Further, a review of service history indicates that no incidents of chafing and arcing have occurred on Group 2 airplanes.\n\n\tIn light of this, the FAA has determined that airplanes identified in the alert service bulletin as Group 2 airplanes are not subject to the unsafe condition. Accordingly, Group 2 airplanes have been excluded from the requirements of this AD.\n\n\tAs a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been included in this rule to clarify this long-standing requirement.\n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.\n\nComments Invited\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.\n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.\n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-NM-44-AD." The postcard will be date stamped and returned to the commenter.\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\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-44-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.\n\n\tThe 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 FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at FAA, 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.

Brett Portwood, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (310) 627-5347; fax (310) 627-5210.