AD 98-25-04

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 series airplanes, that requires repetitive inspections to detect debris in the areas behind the aft lavatory toilet shroud, behind the aft lavatory modules, and below the cabin floor aft of the aft cargo compartment bulkhead; and removal of debris. This amendment also requires modification of the lavatory toilet shroud assemblies and modification of the lavatory entry door louvers, which terminates the repetitive inspections. This amendment is prompted by reports of paper debris collecting below the cabin floor. The actions specified by this AD are intended to prevent paper debris from collecting below the cabin floor, which could result in a potential fire hazard or possible loss of elevator control system redundancy.

Final rule.

98-25-04 MCDONNELL DOUGLAS: Amendment 39-10927. Docket 97-NM-258-AD. \n\n\tApplicability: Model MD-90-30 series airplanes; as listed in paragraph 1.A.1. of McDonnell Douglas Alert Service Bulletin MD90-25A017, Revision R01, dated October 16, 1997, McDonnell Douglas Service Bulletin MD90-25-022, Revision R01, dated October 15, 1997 , and McDonnell Douglas Service Bulletin MD90-25A023, Revision R01, dated October 15, 1997; 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 request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent a potential fire hazard or the possible loss of elevator control system redundancy due to paper debris collecting below the cabin floor, accomplish the following: \n\n\t(a)\tWithin 450 flight hours or 3 months after the effective date of this AD, whichever occurs later, perform an inspection to detect paper and lint debris in the areas behind the aft lavatory toilet shroud, behind the aft lavatory modules, and below the cabin floor aft of the aft cargo compartment bulkhead, in accordance with paragraphs 3.A.1 through 3.A.15 inclusive of the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin MD90-25A017, Revision R01, dated October 16, 1997. If any debris is found, prior to further flight, remove it in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 450 flight hours. \n\n\t(b)\tWithin 12 months after the effective date of this AD, modify the lavatory toilet shroud assemblies in accordance with paragraph 3. ("Accomplishment Instructions") of McDonnell Douglas Service Bulletin MD90-25-022, Revision R01, dated October 15, 1997. \n\n\t(c)\tWithin 12 months after the effective date of this AD, modify the lavatory entry door louvers in accordance with paragraph 3. ("Accomplishment Instructions") of McDonnell Douglas Service Bulletin MD90-25-023, Revision R01, dated October 15, 1997. \n\n\t(d)\tModification of the toilet shroud assemblies and the lavatory entry door louvers in accordance with paragraphs (b) and (c) of this AD constitutes terminating action for the repetitive inspection requirements of paragraph (a) of this AD. \n\n\t(e)\tAn alternative method of compliance or adjustment of the compliance time that providesan 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(f)\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(g)\tThe actions shall be done in accordance with McDonnell Douglas Alert Service Bulletin MD90-25A017, Revision R01, dated October 16, 1997; McDonnell Douglas Service Bulletin MD90-25-022, Revision R01, dated October 15, 1997; and McDonnell Douglas Service Bulletin MD90-25-023, Revision R01, dated October 15, 1997. 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 The Boeing Company, Douglas Products Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). 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(h) This amendment becomes effective on January 7, 1999.

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 MD-90-30 series airplanes was published in the Federal Register on May 20, 1998 (63 FR 27692). That action proposed to require repetitive inspections to detect debris in the areas behind the aft lavatory toilet shroud, behind the aft lavatory modules, and below the cabin floor aft of the aft cargo compartment bulkhead; and removal of debris. That action also proposed to require modification of the lavatory toilet shroud assemblies and modification of the lavatory entry door louvers, which would terminate the repetitive inspections. \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\nSupport for the Proposal \n\n\tOne commenter supports the proposed rule. \n\nRequestto Withdraw the Proposed Rule \n\n\tOne commenter (The Boeing Company, Douglas Products Division (DPD)) "takes serious issue" with a statement that appears in the Summary section of the preamble of the proposed rule. That statement specifies that the proposed rule is prompted by reports of paper debris collecting on the hot pneumatic ducts below the cabin floor. The commenter indicates that it has never seen or reported paper on the pneumatic duct, nor has the commenter received such reports from others. In addition, the commenter states that a lit cigarette has always been suggested as the potential fire hazard - not paper debris on the ducts. \n\n\tThe FAA infers from the commenter's remarks that it requests the proposed AD be withdrawn. The FAA does not concur. The FAA acknowledges that it has not received reports of paper debris collecting on the hot pneumatic ducts. Since paper debris collecting below the cabin floor poses a potential fire hazard and could result in possible loss of elevator control system redundancy, the FAA must issue this final rule to correct that unsafe condition. \n\n\tHowever, the FAA has received reports of paper debris collecting below the cabin floor, and has revised the Summary section and the unsafe condition of this final rule to clarify this information. \n\nRequest to Remove Reporting Requirement \n\n\tOne commenter has no objection to the proposed inspection and modifications specified in the proposal. However, the commenter requests that the proposed rule provide relief from the reporting requirement specified in McDonnell Douglas Alert Service Bulletin MD90-25A017, which is referenced in the proposed rule as the appropriate source of service information. The commenter suggests either exempting operators from the reporting requirement, or only requiring operators to report initial inspection results to McDonnell Douglas. The commenter states that reporting both positive and negative findings of initial and repetitive inspections, as specified in the alert service bulletin, seems to be more of an industry evaluation to determine the viability of the AD, rather than an AD-mandated issue. \n\n\tThe FAA concurs with the commenter's request. The FAA points out that the proposed rule does not specify a requirement for reporting inspection findings to the manufacturer. The alert service bulletin referenced by the commenter is cited in the AD to provide procedures for accomplishment of the required inspection. However, to eliminate any confusion concerning a reporting requirement, this final rule has been revised to cite specific paragraphs of the alert service bulletin that are required to be accomplished. Additionally, the issuance date of Revision R01 of the alert service bulletin has been changed from October 15, 1997, to October 16, 1997, in this final rule. \n\nConclusion \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\nCost Impact \n\n\tThere are approximately 55 Model MD-90-30 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 19 airplanes of U.S. registry will be affected by this AD. \n\n\tIt will take approximately 5 work hours per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection on U.S. operators is estimated to be $5,700, or $300 per airplane, per inspection cycle. \n\n\tIt will take approximately 1 work hour per airplane to accomplish the required modification of the toilet shroud assemblies, at an average labor rate of $60 per work hour. Required parts will be supplied by the manufacturer at no cost to operators. Based on these figures, the cost impact of this modification on U.S. operators is estimated to be $1,140, or $60 per airplane. \n\n\tIt will take approximately 1 work hour per airplane to accomplish the required modification of the lavatory entry door louvers, at an average labor rate of $60 per work hour. Required parts will be supplied by the manufacturer at no cost to operators. Based on these figures, the cost impact of this modification on U.S. operators is estimated to be $1,140, or $60 per airplane. \n\n\tThe 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\nRegulatory Impact \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. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: