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 all Boeing Model 747- 200F, 747-200C, 747-400, 747-400D, and 747-400F series airplanes. That NPRM was published in the Federal Register on September 29, 2005 (70 FR 56860). That NPRM proposed to require repetitive inspections for cracking of certain fuselage internal structure, and repair if necessary. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments received. \n\nSupport for the Proposed AD \n\n\tOne commenter concurs with the contents of the proposed AD and has no additional comments. \n\nRequest To Revise Compliance Time \n\n\tOne commenter, on behalf of an airline, requests that we adjust the proposed grace period for the initial inspection to "greater than 1,000 cycles, but less than or equal to the required SSID (Supplemental Structural Inspection Document) program repetitive inspection interval" if no cracks were found during the SSID inspection. He provides no further justification for the request. \n\n\tWe disagree with the request to revise the grace period. The SSID program is an exploratory program intended for revealing cracks in structure with no prior history of fatigue cracking. The SSID program was substantiated by analysis, whereas this AD was prompted by cracks found during full-scale fatigue tests, and substantiated by updated analysis by Boeing. The inspections and compliance times appropriate for this AD are shorter than those of the SSID program. Because fatigue cracking has been found at the affected structure on the Boeing fatigue test airplanes, we have concluded that the SSID program alone will not adequately prevent undetected cracking of the structure, and that the more stringent inspections and repetitive intervals required by this AD are necessary. We have not changed the final rule regarding this issue. \n\nRequest To Revise Cost Estimate \n\n\tThe same commenter requests that we revise the cost estimate in the proposed AD to reflect the work-hour estimate specified in Boeing Alert Service Bulletin 747-53A2500, dated December 21, 2004 (the source of service information cited in the proposed AD). He states that 1,984 work hours would be an appropriate estimate as this figure includes time for access and close. Because these work hours are not normally provided during scheduled heavy maintenance checks, however, he considers the 260-work-hour estimate, as provided in the proposed AD, misleading. \n\n\tWe recognize that the work hours required for an individual operator to complete all actions associated with an AD may exceed the work hours specified in the proposed cost estimate. However, an AD cannot account for fleetwide variability. Further, the costs of compliance discussed in a proposed AD represent only the time necessary to perform the specific actions actually proposed. The cost estimate typically does not include incidental costs such as access and close. Therefore, we don't consider it appropriate to attribute those associated costs to the AD. We have not changed the final rule regarding this issue. \n\nExplanation of Change Made to This AD \n\n\tWe have simplified paragraph (g) of this AD by referring to the "Alternative Methods of Compliance (AMOCs)" paragraph of this AD for repair methods. \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 with the change described previously. We have determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCosts of Compliance \n\n\tThere are about 706 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD. \n\n\tEstimated Costs \n\t(Per inspection cycle) \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nAction \nWork \nhours \nAverage \nlabor rate \nper hour \nParts \nCost per \nairplane \nNumber of U.S.-\nregistered \nairplanes \nFleet cost \nInspections \n260 \n$65 \nNone required \n$16,900 \n107 \n$1,808,300 \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):