AD 99-09-13

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 757-200 series airplanes, that requires modifications to the attachment installation of the forward lavatory. This amendment is prompted by a stress analysis report indicating that the forward lavatory could break free from the upper and/or lower attachments during an emergency landing. The actions specified by this AD are intended to prevent failure of the attachment installation of the forward lavatory during an emergency landing, which could result in injury to the crew and passengers.

Final rule

99-09-13 BOEING: Amendment 39-11146. Docket 98-NM-37-AD. \n\n\tApplicability: Model 757-200 series airplanes; as listed in Boeing Service Bulletin 757-25-0181, dated June 26, 1997, and Boeing Alert Service Bulletin 757-25A0187, dated September 18, 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 (d) 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 failure of the attachment installation of the forward lavatory during an emergency landing, which could result in injury to the crew and passengers, accomplish the following: \n\n\t(a)\tFor passenger airplanes identified in Boeing Service Bulletin 757-25-0181, dated June 26, 1997: Within 24 months or 3,000 flight cycles after the effective date of this AD, whichever occurs first, install a doubler to the upper attachment installation of the forward lavatory in accordance with Boeing Service Bulletin 757-25-0181, dated June 26, 1997. \n\n\t(b)\tFor freighter airplanes identified in Boeing Alert Service Bulletin 757-25A0187, dated September 18, 1997: Within 24 months or 3,000 flight cycles after the effective date of this AD, whichever occurs first, install floor panel inserts, a retention fitting assembly, and a doubler assembly to the lower attachment installation of the forward lavatory, in accordance with Boeing Alert Service Bulletin 757-25A0187, dated September 18, 1997. \n\n\t(c)\tAs of the effective date of this AD, no person shall install a floor panel, part number 141N5410-12 or 141N5410-28, on any airplane. \n\n\tNOTE 2: Floor panels having part numbers 141N5410-12 and 141N5410-28 are only installed on freighter airplanes and are not used on passenger airplanes. \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, Seattle 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, Seattle ACO. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \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 actions shall be done in accordance with Boeing Service Bulletin 757-25-0181, dated June 26, 1997, and Boeing Alert Service Bulletin 757-25A0187, dated September 18, 1997, as applicable. 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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; 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 June 1, 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 Boeing Model 757-200 series airplanes was published in the Federal Register on May 12, 1998 (63 FR 26104). That action proposed to require modifications to the attachment installation of the forward lavatory. \n\nComments \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, three commenters offer no objection to the proposed rule, and one commenter states that the proposed rule will not apply to it. \n\nRequest to Extend Compliance Time \n\n\tOne commenter requests that the compliance time for the modification requirements be extended from 18 months after the effective date of this AD to 24 months or 3,000 flight cycles, whichever occurs later. The commenter states that such a schedule would coincide with its normal maintenance interval of 24 months or 3,000 flight cycles. The commenter states that the 18-month compliance time would be unnecessarily restrictive and would force it to schedule special maintenance visits for some of its airplanes. \n\n\tThe FAA concurs with the commenter's request to extend the compliance time for the modification requirements. However, the FAA finds that extending the compliance time for both passenger and freighter airplanes from 18 months to 24 months or 3,000 flight cycles after the effective date of this AD, whichever occurs first, will not adversely affect safety, and will allow the modification to be performed at a base during regularly scheduled maintenance. Therefore, paragraphs (a) and (b) of this final rule have been revised accordingly. \n\nRequest to Include A Note About Floor Panels on Freighters \n\n\tOne of the commenters who expressed no objection to the proposed rule requests that a note be inserted in the final rule to clarify that the floor panels identified in paragraph (c) of the proposed rule are applicable only for freighter airplanes. \n\n\tThe FAA concurs with the commenter's request. The floor panels specified in paragraph (c) of the final rule are not installed on passenger airplanes. Therefore, a new NOTE 2 has been inserted into the final rule to clarify that the floor panels specified in paragraph (c) of the final rule are only installed on freighter airplanes and are not used on passenger airplanes. \n\nRequest to Revise the Service Bulletin \n\n\tOne commenter maintains that it is impossible to accomplish the instructions specified in Boeing Service Bulletin 757-25-0181, dated June 26, 1997, and requests that the service bulletin be revised. The commenter states that a certain doubler specified in the service bulletin does not always have adequate edge margin on existing fasteners. The commenter further states that it fabricated a new doublerto accommodate the fastener spacing and, if this condition is not addressed in rulemaking action, it will be required to request an alternative method of compliance for each airplane that requires a new doubler. \n\n\tThe commenter makes no specific request for a change to the proposal. However, Boeing has been advised of the commenter's situation, and it will survey other operators to determine whether they also have experienced the same short edge margin condition. Boeing will revise the service bulletin if necessary. \n\n\tThe FAA concurs that the commenter will require an alternative method of compliance to allow use of a new doubler of its own manufacture. Under the provisions of paragraph (d) of this final rule, the FAA may consider requests for approval of an alternative method of compliance if sufficient data are submitted to substantiate that the new doubler would provide an acceptable level of safety. No change to the final rule in this regard is necessary. \n\nRequest to Increase the Strength of the Lavatory Attachments \n\n\tThe commenter that supports the proposed rule also requests that the strength of the subject lavatory attachments be increased beyond the limit required by 14 CFR 25.561. The commenter states that survivable accident impacts can exceed the 9g static limit before the structure of the airplane breaks up; therefore, the attachments of all structures in the cabin of the airplane should be designed to retain the structure up to a level where the fuselage frames and skin stringers are no longer able to hold together. \n\n\tThe FAA acknowledges the commenter's concern. However, while there may be merit to the commenter's suggestions, this AD is not the appropriate context in which to evaluate those suggestions. As the commenter states, such an increase in the strength of the lavatory attachments would require a change to the 14 CFR 25.561. The FAA has determined that an unsafe condition exists, and that the actions required by this AD are adequate in order to ensure the continued safety of the affected fleet. No change to the final rule in this regard is necessary. \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 described previously. 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 333 airplanes of the affected design in the worldwide fleet. The FAA estimates that 225 airplanes of U.S. registry will be affected by this AD: 164 passenger airplanes and 61 freighter airplanes. \n\n\tIt will take approximately 10 work hours per passenger airplane to accomplish the required modification, at an average labor rate of $60 per work hour. Required parts will cost approximately $100 per airplane. Based on these figures, the cost impact of the required modification on U.S. operators is estimated to be $114,800, or $700 per passenger airplane. \n\n\tIt will take approximately 42 work hours per freighter airplane to accomplish the required modification, at an average labor rate of $60 per work hour. Required parts will be provided by the airplane manufacturer at no cost to the operators. Based on these figures, the cost impact of this required modification on U.S. operators is estimated to be $153,720, or $2,520 per freighter airplane. \n\n\tThe cost impact figures discussed above are 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 thevarious 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\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. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: