AD 95-21-04

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 series airplanes, that currently requires modification of the support structure of the cargo liner. That AD was 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 that AD are intended to prevent fire and/or smoke due to chafing and arcing of the vacuum waste exhaust port heater. This amendment expands the applicability of the existing rule to include additional affected airplanes. It also provides for an alternative method of modification.

Final rule; request for comments.

95-21-04 McDONNELL DOUGLAS: Amendment 39-9389. Docket 95-NM-184-AD. Supersedes AD 95-08-09, Amendment 39-9198. \n\n\tApplicability: Model MD-11 series airplanes; as listed in McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 1995, and Revision 1, dated June 30, 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 otherwise 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 (d) of this AD to request approval fromthe 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 a fire and/or smoke due to chafing and arcing of the heater, accomplish the following: \n\n\t(a)\tFor airplanes listed in McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 1995: Within 30 days after May 2, 1995 (the effective date of AD 95-08-09, amendment 39-9198), modify the support structure of the cargo liner, in accordance with McDonnell Douglas MD-11 Alert Service Bulletin MD11-38A044, dated March 22, 1995, or Revision1, dated June 30, 1995. \n\n\t(b)\tFor airplanes listed in McDonnell Douglas Alert Service Bulletin MD11-38A044, Revision 1, dated June 30, 1995, and not subject to paragraph (a) of this AD: Within 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, or Revision 1, dated June 30, 1995. \n\n\t(c)\tAs of May 2, 1995, 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, or Revision 1, dated June 30, 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(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 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\tNOTE 3: Alternative methods of compliance previously granted for AD 95-08-09, amendment 39-9198, continue to be considered as acceptable alternative methods of compliance with this amendment. \n\n\t(e)\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(f)\tThe modification shall be done in accordance with McDonnell Douglas Alert Service Bulletin MD11-38A044, dated March 22, 1995; or McDonnell Douglas Alert Service Bulletin MD11-38A044, Revision 1, dated June 30, 1995. Incorporation by reference of the former service bulletin was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of May 2, 1995 (60 FR 19158, April 17, 1995). Incorporation by reference of the latter service bulletin 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(g)\tThis amendment becomes effective on October 27, 1995.

On April 5, 1995, the FAA issued AD 95-08-09, amendment 39-9198 (60 FR 19158, April 17, 1995), which is applicable to certain McDonnell Douglas Model MD-11 series airplanes. That AD requires modification of the support structure of the cargo liner. The modification entails removing the baffle assemblies and trimming the insulation blankets surrounding the vacuum waste exhaust duct, which will reduce chafing and minimize the possibility of igniting the insulation blanket. These modification procedures also include making the circuit breaker inoperative to deactivate the exhaust duct heater until a new heater can be installed. \n\n\tThat AD was 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 required by that AD are intended to prevent fire and/or smoke due to chafing and arcing of the vacuum waste exhaust port heater. \n\n\tSince the issuance of that AD, the FAA has reviewed and approved McDonnell Douglas Service Bulletin MD11-38A044, Revision 1, dated June 30, 1995. This revised service bulletin is essentially identical to the original issue, which was cited in AD 95-08-09 as the appropriate source of service information, but differs in two aspects: \n\n\t1. The revised service bulletin includes three additional airplanes in its effectivity listing. These airplanes have been identified as being subject to the same unsafe condition that was addressed by AD 95-08-09. \n\n\t2. The revised service bulletin provides instructions for conducting an alternative procedure in the modification process. This alternative procedure deactivates the exhaust duct heater by removing wires from the terminal strip, in lieu of making its circuit breaker inoperative until a new heater is installed. \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 95-08-09 to continue to require modification of the support structure of the cargo liner. The applicability of the AD is expanded to include three additional airplanes that have been determined to be subject to the unsafe condition addressed by the existing rule. Additionally, this AD provides for the use of an alternative procedure in the modification process, as specified in the revised service bulletin described previously. \n\n\tAlthough all of the airplanes identified in the effectivity listing of the referenced alert service bulletins 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 finds that the potential for chafing and arcing to occur on Group 1 airplanes is much greater. A review of service history indicates that no incidents of chafing or arcing have occurred on Group 2 airplanes. In light of this, the FAA has determined that airplanes identified in the alert service bulletins as Group 2 airplanes are not subject to the unsafe condition. Accordingly, Group 2 airplanes continue to be excluded from the requirements of this (superseding) AD. \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\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-184-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\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. The authority citation for part 39 continues to read as follows: \n\nAuthority: 49 USC 106(g), 40101, 40113, 44701. \n\n§ 39.13 - (Amended) \n\n\t2. Section 39.13 is amended by removing amendment 39-9198 (60 FR 19158, April 17, 1995), and by adding a new airworthiness directive (AD), amendment 39-9389, to read as follows: