Discussion \n\n\tWe have received reports of cracked outer V-blades in the Rolls- Royce engine thrust reversers on Boeing Model 777-200 and -300 series airplanes. The cracks were found in the top and bottom ends of the V- blade. The outer V-blade engages the aft end of the engine fan case to transmit fore and aft loads from the thrust reversers. Initial analysis of the V-blade did not include bending loads, and consequently the fatigue margins were not sufficient. A thrust reverser that separates from the airplane during normal reverse thrust or refused takeoff can damage other airplane areas. If a thrust reverser separates from the airplane during a refused takeoff, the engine could produce forward thrust, resulting in unexpected thrust asymmetry and a possible runway excursion. \n\nRelevant Service Information \n\n\tWe have reviewed Boeing Special Attention Service Bulletin 777-78- 0064, Revision 1, dated November 30, 2006. The service bulletin describesprocedures for doing repetitive detailed inspections to detect cracks in the outer V-blade of the thrust reverser, replacing cracked V-blades with serviceable parts, and sending a report of the inspection results to Boeing. The compliance time for the initial inspection ranges from 250 to 6,000 flight cycles after the effective date of the AD, depending on the number of flight cycles on the V- blade, with repetitive intervals not to exceed 2,000 flight cycles from the last detailed inspection. \n\n\tWe have also reviewed Boeing Special Attention Service Bulletin 777-78-0061, dated July 6, 2006, which describes procedures for doing a special detailed inspection to detect cracks in the outer V-blade of the thrust reverser in addition to a special detailed (eddy current or fluorescent penetrant) inspection to detect cracks in the fay surface area of the lower chord of the torque box where the outer V-blade attaches. If a crack is found in the outer V-blade, a new configuration V-blade is installed. If no crack is found, the V-blade is changed and installed with new support brackets at the top and bottom ends. The service bulletin also specifies contacting Boeing for repair instructions for cracks found in the torque box lower chord. \n\n\tAccomplishment of the actions specified in Special Attention Service Bulletin 777-78-0061 eliminates the need for the repetitive inspections of Special Attention Service Bulletin 777-78-0064. \n\nFAA's Determination and Requirements of This AD \n\n\tThe unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. For this reason, we are issuing this AD to prevent separation of a thrust reverser from the airplane during normal reverse thrust or during a refused takeoff, which could result in impact damage to other airplane areas. If a thrust reverser separates from the airplane during a refused takeoff, the engine could produce forward thrust, resulting in unexpected thrust asymmetry anda possible runway excursion. This AD requires accomplishing the actions specified in Boeing Special Attention Service Bulletin 777-78-0064 described previously. This AD also provides for an optional terminating action for the repetitive inspections. \n\nDifference Between the AD and Service Information \n\n\tBoeing Special Attention Service Bulletin 777-78-0061 specifies to contact the manufacturer for instructions on how to repair certain conditions, but this AD requires repairing those conditions, if accomplished, in one of the following ways: \n\n\tUsing a method that we approve; or \n\n\tUsing data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to approve repair methods. \n\nInterim Action \n\n\tWe consider this AD interim action. We are considering mandating the optional terminating action specified in Boeing Special Attention Service Bulletin 777-78-0061, which terminates the repetitive inspections required by this AD. However, the planned compliance time for this terminating action would allow enough time to provide notice and opportunity for prior public comment on the merits of the actions. \n\nFAA's Determination of the Effective Date \n\n\tSince an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists to make this AD effective in less than 30 days. \n\nComments Invited \n\n\tThis AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include "Docket No. FAA-2006- 26675; Directorate Identifier 2006-NM-203-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it. \n\n\tWe will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov. \n\nExamining 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 DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them. \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 the regulation: \n\n\t1. Is not a "significant regulatory action'' under Executive Order 12866; \n\n\t2. Is not a "significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the RegulatoryFlexibility 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):