AD 95-11-03

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires replacement of the existing pressure relief valve in the potable water system with a non-adjustable, single setting valve. This amendment is prompted by reports of potable water tanks that ruptured and resulted in damage to the passenger compartment. The actions specified by this AD are intended to prevent injury to the crew and passengers and damage to the passenger compartment due to an explosive failure of the potable water tank.

Final rule

95-11-03 BOEING: Amendment 39-9237. Docket 94-NM-190-AD. \n\n\tApplicability: Model 747 series airplanes, line positions 1 through 1013 inclusive; 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) 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 explosive failure of the potable water tank, which could cause damage to the passenger compartment and result in injury to the crew and passengers, accomplish the following: \n\n\t(a)\tWithin 6 months after the effective date of this AD, replace the existing pressure relief valve in the potable water system with a non-adjustable, single setting valve, in accordance with Boeing Alert Service Bulletin 747-38A2105, Revision 1, dated March 2, 1995. \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, 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 2: 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(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 replacement shall be done in accordance with Boeing Service Bulletin 747- 38A2105, Revision 1, dated March 2, 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 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(e)\tThis amendment becomes effective on June 23, 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 Boeing Model 747 series airplanes was published in the Federal Register on December 15, 1994 (59 FR 64629). That action proposed to require replacement of the existing pressure relief valve in the potable water system with a non-adjustable, single setting valve. \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\tTwo commenters support the rule. \n\n\tThe Air Transport Association of America (ATA), on behalf of several of its members, supports the proposed rule, but requests that the proposed compliance time of 6 months be extended to 12 months. ATA states that the 6-month compliance time would require several members to "special schedule" their maintenance planning in order to accomplish the proposed replacement of the pressure relief valve in the potable water system. The FAA does not concur with the commenter's request to extend the compliance time. In developing an appropriate compliance time for this action, the FAA considered not only the degree of urgency associated with addressing the subject unsafe condition, but the availability of required parts and the practical aspect of replacing the pressure relief valve within a maximum interval of time allowable for all affected airplanes to continue to operate without compromising safety. The manufacturer has advised that an ample number of required parts will be available for the replacement of the pressure relief valve for the U.S. fleet within the proposed compliance period. Additionally, the replacement actions required by this AD are uncomplicated and do not require special scheduling; the inspection could be accomplished during an "A" check, which occurs every one or two weeks. However, under the provisions of paragraph (b) of the final rule, the FAA may approve requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. \n\n\tSince issuance of the Notice, Boeing has issued Revision 1, dated March 2, 1995, of Boeing Alert Service Bulletin 747-38A2105. This alert service bulletin changes airplane grouping by putting all Model 747 SP series airplanes in Group 3, and changes the part numbers of the valves required for Group 1 and Group 2 airplanes. Revision 1 does not increase the scope of the work required. Therefore, the FAA has revised the final rule to reflect the latest revision to the service bulletin as the appropriate 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 change previously described. The FAA has determinedthat this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\n\tThere are approximately 983 Boeing Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 205 airplanes of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $120 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $73,800, or $360 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\n List 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\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1.\tThe authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. § 39.13 - (Amended) \n\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: