Examining the Docket \n\n\tYou may examine the 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 727 airplanes. That NPRM was published in the Federal Register on April 4, 2005 (70 FR 16979). That NPRM proposed to require determining whether any float switches are installed in the fuel tanks, and corrective actions 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 that have been received on the NPRM. \n\nSupport forProposed AD \n\n\tOne commenter, the airplane manufacturer, concurs with the content of the proposed AD. \n\nRequest To Change Applicability \n\n\tOne commenter asks that the applicability specified in the proposed AD be limited to Boeing Model 727 airplanes that have float switches installed. The commenter states that the effectivity of the proposed AD will encompass all Boeing Model 727-100 airplanes operated by them, even though Model 727-100 airplanes are not included in the effectivity specified in the service bulletin referenced in the proposed AD. The commenter adds that the effectivity in the referenced service bulletin is limited to airplanes with factory installed auxiliary fuel tanks; the design for Model 727-100 airplanes does not include float switches in the main fuel tanks because those airplanes utilize the Volumetric Top-Off system instead. The commenter realizes that we are concerned that the effectivity of the referenced service bulletin may not encompass all possiblescenarios involving the subject float switches, as stated in the Supplementary Information section of the proposed AD. In consideration of this concern, the commenter notes that the effectivity of the proposed AD can be reduced to include only airplanes where the design, as delivered or modified, utilizes float switches in the airplane fuel tanks. The commenter adds that, the requested change has no effect on safety, but does remove the burden of showing compliance to a known non-applicable configuration. \n\n\tWe do not agree with the commenter. The planning information specified in the referenced service bulletin identifies only Boeing Model 727-100 airplanes delivered with two auxiliary fuel tanks installed. However, the effectivity specified in the service bulletin identifies all Boeing Model 727-100 and -200 airplanes with active Boeing fueling float switch shutoff systems installed. We point out that the subject of this AD is the float switch itself--regardless of the airplane model on which it is installed. To help operators determine if a particular airplane is subject to this AD, we have included all airplane models on which the float switch may be installed in the applicability of this AD. However, operators must determine if the float switch is installed on their airplanes. As specified in the AD, this determination can be made by a review of airplane maintenance records, instead of an inspection of the fuel tanks; such a review would not result in an undue burden to operators. We have made no change to the final rule in this regard. \n\nExplanation of Change to Applicability \n\n\tWe have revised the applicability of the proposed AD to identify model designations as published in the most recent type certificate data sheet for the affected models. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been received, and determined that air safety and the public interest require adopting the AD with the change described previously. 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 1,300 airplanes of the affected design in the worldwide fleet. This AD affects about 800 airplanes of U.S. registry. \n\n\tThe inspections (for presence and model of float switch) take about 1 work hour, at an average labor rate of $65 per hour. Based on these figures, the estimated cost of the inspections for U.S. operators is $52,000, or $65 per airplane. \n\n\tThe following table provides the estimated costs for U.S. operators to replace the float switches, if necessary. We estimate that about 162 airplanes may require parts replacement. \n\n\tEstimated Costs \n\n\n\nAirplane group \nAirplane model \nNumber of auxiliary fuel tanks \nWork hours \nAverage hourly labor rate \nParts \nCost per airplane \n1 \n727-200 \n0 \n27 \n$65 \n$4,174 \n$5,929 \n2 \n727-200 \n1 \n9 \n65 \n1,542 \n2,127 \n3 \n727-200 \n2 \n14 \n65 \n3,108 \n4,018 \n4 \n727-200 \n3 \n18 \n65 \n4,626 \n5,796 \n5 \n727-200 \n4 \n23 \n65 \n6,168 \n7,663 \n6 \n727-100 \n2 \n14 \n65 \n3,079 \n3,989 \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 rulemakingaction. \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):