Examining the Docket \n\n\tYou may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section. \n\nDiscussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Boeing Model 747-400 series airplanes. That NPRM was published in the Federal Register on December 9, 2005 (70 FR 73171). That NPRM proposed to require inspecting the support bracket of the crew oxygen cylinder installation to determine the manufacturing date marked on the support, and performing corrective action if necessary. \n\nComments \n\n\tWe provided the public the opportunity to participate inthe development of this AD. We have considered the comments received. \n\nRequest To Revise Estimated Costs of Compliance \n\n\tBoeing requests that we revise the estimated Costs of Compliance stated in the NPRM to include the work hours needed for replacing any support bracket of the crew oxygen cylinder having a manufacturing date that is within a certain range, and for testing following such replacement. Boeing notes that the NPRM included the estimated cost of the inspection only. \n\n\tWe do not agree. The economic analysis of an AD is limited to the cost of actions that are actually required. The economic analysis does not consider the costs of conditional actions, such as corrective actions (e.g., replacing a support having an affected manufacturing date with a new support). Such conditional action would be required-- regardless of AD direction--to correct an unsafe condition identified in an airplane and to ensure that the airplane is operated in an airworthy condition, as required by the Federal Aviation Regulations. We have not changed the AD in this regard. \n\nRequest To Refer to Replacement \n\n\tBoeing also requests that we revise the "title section" or "header section" to refer to "Inspection/Replacement" in lieu of "Inspection." The commenter states that the required action is not only to inspect to determine the manufacturing date marked on the support bracket of the crew oxygen cylinder, but also to replace certain support assemblies. \n\n\tWe do not agree that any change to the AD is needed with regard to this request. We are unable to determine what section of the AD that the commenter is requesting be changed. We note that the Summary section of the NPRM states that the proposed AD would require "inspecting the support bracket of the crew oxygen cylinder installation to determine the manufacturing date marked on the support, and performing corrective action if necessary." We also note that the Relevant Service Information section of the NPRM refersto the same actions and further explains that "The corrective action is replacing, with a new support, any support with a manufacturing date that is within a certain range." The heading of paragraph (f) of the NPRM (and this AD) describe the actions in paragraph (f) as an "Inspection and Corrective Action," and the requirements of that paragraph are consistent with the actions described in the Summary and Relevant Service Information sections of the NPRM. Since all of these sections refer, at minimum, to an inspection and corrective action, we find no section of this AD needs to be made more specific. Thus we have not changed the AD in this regard. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD as proposed. \n\nCosts of Compliance \n\n\tThere are about 70 airplanes of the affected design in the worldwide fleet. This AD will affect about 15 airplanes of U.S. registry. The required inspection will take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of this AD for U.S. operators is $975, or $65 per airplane. \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\n\tWe are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect 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. \n\n\tFor the reasons discussed above, I certify that this AD: \n\n\t(1) Is not a "significant regulatory action" under Executive Order 12866; \n\n\t(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t(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. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.See the ADDRESSES section for a location to examine the regulatory evaluation. \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\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):