The FAA proposed to amend 14 CFR Part 39 with an AD for certain Boeing Model 737-600, -700, -800, and -900 series airplanes. That action, published in the Federal Register on January 5, 2005 (70 FR 733), proposed to require installing and testing an updated version of the operational program software of the flight control computers. \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 submitted on the proposed AD. \n\nSupport for the Proposed AD \n\n\tTwo commenters support the AD as proposed. A third commenter supports the intent of the proposed AD. \n\nRequest To Prohibit Testing in Revenue Service \n\n\tOne commenter requests that we prohibit testing of the updated software in revenue service. The commenter provides no justification for the request. We infer that the commenter believes the proposed AD would require a flight test of the updated software installation, and that performing a flight test during revenue service would pose undue hazard to airplane occupants. \n\n\tWe do not agree because we believe the commenter has misunderstood the testing requirement of this AD. The test of the updated version of the operational program (OPS) software is a ground test performed by maintenance personnel, not a flight test. This test, which must be satisfactorily accomplished before returning an airplane to service, is adequate for ensuring that the OPS software is properly installed and updated. Therefore, no change to this final rule is necessary in this regard. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been 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 155 airplanes of the affected design in the worldwide fleet. This AD affects about 34 airplanes of U.S. registry. The actions take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Required parts cost about $0 per airplane. Based on these figures, the estimated cost of this AD for U.S. operators is $4,420, or $130 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 conditionthat 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 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 FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):