Discussion \n\n\tOn October 2, 2006, we issued AD 2006-20-51, amendment 39-14786 (71 FR 59651, October 11, 2006), for certain Boeing Model 777-200LR and - 300ER series airplanes. That AD requires revising the airplane flight manual to prohibit takeoffs at less than full-rated thrust. That AD resulted from a report of two occurrences of engine thrust rollback (reduction) during takeoff. We issued that AD to prevent dual-engine thrust rollback, which could result in the airplane failing to lift off before reaching the end of the runway or failing to clear obstacles below the takeoff flight path. \n\nActions Since Existing AD Was Issued \n\n\tSince issuance of AD 2006-20-51, Boeing has informed us that no U.S.-registered airplanes have full authority digital engine control (FADEC) software version A.0.4.5 installed, and that software version A.0.4.6 is being installed in production. In addition, we have determined that the affected airplanes are limited to those subject to the identified unsafe condition with FADEC electronic engine control (EEC) software version A.0.4.5 installed. We have also determined that FADEC software version A.0.4.6 has incorporated software revisions that prevent the reported roll-back conditions from occurring. Therefore, we also have determined that the applicability of AD 2006-20-51 can be revised to apply only to affected airplanes equipped with FADEC software version A.0.4.5. \n\nFAA's Determination and Requirements of This AD \n\n\tNo airplanes affected by this AD are on the U.S. Register. We are issuing this AD because the unsafe condition described previously is likely to exist or develop on other products of the(se) same type design(s) that could be registered in the United States in the future. This AD revises AD 2006-20-51. This AD retains the requirements of the existing AD and reduces the applicability of the existing AD. \n\tSince no U.S. registered airplanes are affected by this AD, notice and opportunity for public comment before issuing this AD are unnecessary. \n\nInterim Action \n\n\tWe consider the requirements of this AD "interim action.'' The manufacturer is developing a modification to address the unsafe condition (i.e., decreased takeoff thrust). We might consider further rulemaking if a modification is developed, approved, and available. \n\nComments Invited \n\n\tThis AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments before it becomes effective. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include "Docket No. FAA-2008-1241; Directorate Identifier 2008-NM-121-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this AD because of those comments. \n\tWe will post all comments we receive, without change, to http:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this AD. \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\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 withinthe 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\tThis 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\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a "significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a "significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), and \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\tYou can find our regulatory evaluation and the estimated costs of compliance in the ADdocket. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, 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 removing amendment 39-14786 (71 FR 59651, October 11, 2006) and adding the following new AD: