The FAA proposed to amend 14 CFR part 39 with an AD for certain Boeing Model 747-200C and 747-200F series airplanes. That action, published in the Federal Register on March 23, 2005 (70 FR 14587), proposed to require one-time inspections for cracks and material loss in the fuselage skin above the stringer (STR) 23 lap splice, between Body Station (BS) 282 and BS 298, 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 comment that has been submitted on the proposed AD. \n\nRequest To Re-Evaluate Need for the Proposed Rule \n\n\tOne commenter, an airplane operator, notes that it has previously inspected the fuselage skin thickness at the affected area on two of its ten production freighter airplanes. The inspections, which the commenter points out were conducted at the manufacturer's recommendation, showed skin thickness of 0.060 inch or greater on both airplanes.The commenter asserts that our justification for adopting the proposed AD should cite the results of its inspections and any similar inspections conducted at the manufacturer's request by other operators; and notes that Boeing Special Attention Service Bulletin 747-53-2493, dated July 3, 2003, cites only one instance of the problem that is prompting the proposed AD. The commenter acknowledges the significance of fuselage skin cracking, and recognizes the fact that the maintenance program for the affected Model 747-200C and 747-200F series airplanes includes external visual inspections of the affected area at regular intervals. However, the commenter questions our justification for adopting the proposed AD. \n\n\tWe infer that the commenter is questioning whether the proposed AD addresses a safety issue and, if not, we further infer that the commenter requests that we withdraw the proposed AD. We disagree. Although the commenter had no findings of cracking or blended skin on two of itsairplanes, other respondents to the manufacturer's survey did report airplanes with skin thickness that was below the minimum. In addition, there are many airplanes affected by this proposed AD that have not yet been inspected. \n\n\tHowever, we do agree that we should clarify the unsafe condition. Investigation of the crack report that prompted this proposed AD showed that the skin at the crack location was not the correct thickness. Boeing audited its manufacturing processes and discovered that assembly techniques of the skin panels during final assembly at the factory were the likely cause of the thin skin at the affected sections. It is very likely that the same condition may exist on other airplanes that were manufactured using the same techniques. Furthermore, the finding that precipitated this proposed AD was a three-inch crack in the upper row of the lap splice just above the upper row. Cracking in this area is critical due to its proximity to the upper row and possible interaction of cracks between the blended area and the upper row. Therefore, the crack finding, coupled with the likelihood that the thin skin condition exists on other airplanes, provides sufficient justification for adopting the proposed AD to detect and correct cracks or material loss in the fuselage skin. \n\n\tWe have not changed the final rule in this regard. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comment that was submitted, and determined that air safety and the public interest require adopting the AD as proposed. \n\nCosts of Compliance \n\n\tThere are about 77 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\n\nAction \nWork hours \nAverage labor rate per hour \nParts \nCost per airplane \nNumber of U.S.-\nregistered airplanes \nFleet cost \nInspections \n6 \n$65 \nNone .\n$390 \n20 \n$7,800 \n\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. 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 bythe 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 FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):