Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 747-200B, 747-300, 747-400, 747-400D, 747-400F series airplanes, and Model 767 series airplanes, powered by General Electric (GE) CF6- 80C2 engines. The NPRM published in the Federal Register on January 16, 2013 (78 FR 3363). The NPRM was prompted by reports of failure of the electro mechanical brake flexshaft (short flexshaft) of the thrust reverser actuation system (TRAS). The NPRM proposed to require replacing the short flexshaft on each engine with a new short flexshaft, testing of the electro-mechanical brake and center drive unit (CDU) cone brake to verify the holding torque, and performing related investigative and corrective actions if necessary. We are issuing this AD to prevent an uncommanded in-flight thrust reverser deployment and consequent loss of control of the airplane. \n\nCommentsWe gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal (78 FR 3363, January 16, 2013) and the FAA's response to each comment. \n\nRequest To Clarify Applicability and Reliability Difference Between Engine Models \n\n\n\tAir France Industries asked if the thrust reversers on GE CF6-80E1 powered airplanes are addressed by the NPRM (78 FR 3363, January 16, 2013), and if the flexshaft reliability difference between GE CF6-80C2 and CF6-80E1 engines is due to the systematic introduction of the double P-Seal on translating cowls on GE CF6-80E1 engines. \n\tWe agree to clarify why the NPRM (78 FR 3363, January 16, 2013) did not address the GE CF6-80E1 thrust reversers. This final rule was prompted by reports of failure of the electro-mechanical brake flexshaft (short flexshaft) of the TRAS on Model 747 and Model 767 airplanes powered by GE CF6-80C2 engines. Therefore, we did not conduct a safety assessment onairplanes powered by GE CF6-80E1 engines. We have not determined that the double P-Seal was a contributing factor to the failure of the flexshaft on GE CF6-80C2 engines. We are aware that this defective flexshaft could be installed on other engines. We have contacted the appropriate office to address the safety concerns regarding this defective flexshaft on other airplane models, and might consider additional rulemaking if an unsafe condition is identified on other engines. We have not changed this final rule in this regard. \n\nRequest To Include Additional Service Information \n\n\n\tUPS requested that we allow the use of Middle River Aircraft Systems (MRAS) CF6-80C2B Service Bulletin 78-1168, Revision 1, dated August 26, 2010, to comply with the flexshaft replacement proposed by paragraph (g) of the NPRM (78 FR 3363, January 16, 2013). UPS stated that it has fully complied with the flexshaft replacement requirement using this service information. \n\tWe agree with the commenter's request. Since we issued the NPRM (78 FR 3363, January 16, 2013), we have determined that flexshaft replacements done in accordance with Middle River Aircraft Systems CF6- 80C2B Service Bulletin 78-1168, Revision 1, dated August 26, 2010; and Revision 2, dated April 19, 2011; meet the intent of this final rule. We have changed paragraph (g) of this final rule to include Middle River Aircraft Systems CF6-80C2B Service Bulletin 78-1168, Revision 2, dated April 19, 2011, as an appropriate source of service information; and we have also added new paragraph (m) to this final rule to provide credit for actions done prior to the effective date of this final rule using Middle River Aircraft Systems CF6-80C2B Service Bulletin 78-1168, Revision 1, dated August 26, 2010. We have redesignated subsequent paragraphs accordingly. \n\nRequest To Update Parts Cost \n\n\n\tMRAS provided current cost data and requested that we update the estimated parts costs accordingly. \n\tWe agree to update the estimated parts costs. We have changed the estimated parts cost to $4,031 for each flexshaft, which changes the estimated parts cost to $32,248 for a Model 747 airplane, and to $16,124 for a Model 767 airplane. \n\nRequest To Change Parts Installation Prohibition Paragraph \n\n\n\tBoeing and MRAS requested that we change paragraph (k) of the NPRM (78 FR 3363, January 16, 2013), which would prohibit installation of part number (P/N) 3278500-( ), on any airplane, to specify that this prohibition applies only to Boeing airplanes. MRAS stated that P/N 3278500-( ) is still certified on Airbus Model A330 airplanes. \n\tWe partially agree with the commenters' request. This final rule applies only to the airplanes identified in paragraph (c) of this final rule. Paragraph (k) of this final rule specifies ''any airplane,'' which refers to the airplanes identified in paragraph (c) of this final rule. However, to add clarity to this final rule, we have revised paragraph (k) of this final rule to specify that the parts prohibition applies only to the airplanes identified in paragraph (c) of this final rule. \n\nRequest To Clarify CDU Cone Brake Replacement Action \n\n\n\tBoeing and MRAS requested that we change the fifth paragraph of the Relevant Service Information section of the NPRM (78 FR 3363, January 16, 2013), which specified that the corrective action for a CDU cone brake test failure is replacement of the CDU cone brake with a new CDU cone brake. The commenters stated that the cone brake is not a line- replaceable unit (LRU), and that if a CDU cone brake fails, the entire CDU must be replaced with a serviceable CDU. MRAS stated that the cone brake within the CDU can be replaced only in a component maintenance shop. \n\tWe agree that the cone brake is not an LRU, and that the corrective action for a CDU cone brake test failure is replacement of the CDU with a new or serviceable CDU. Paragraph (i) of this final rule requires doing the corrective action for a failed cone brake functionaltest in accordance with certain applicable service information, which does specify replacing the CDU--not just the cone brake--after a failed test. The Relevant Service Information \n\n((Page 15662)) \n\nparagraph of the NPRM (78 FR 3363, January 16, 2013) is not repeated in this final rule; therefore, we have not changed this final rule in this regard. \n\nRequest To Extend the Repetitive Inspection Interval \n\n\n\tAir New Zealand (ANZ) requested that we extend the repetitive inspection interval specified in paragraph (h) of the NPRM (78 FR 3363, January 16, 2013) to 3,000 flight hours or greater. ANZ cited several previous alternative methods of compliance (AMOC) approvals for issued ADs to extend the inspection intervals on the thrust reverser CDU cone brake and the electro-mechanical brakes. \n\tWe do not agree to extend the repetitive inspection interval proposed in the NPRM (78 FR 3363, January 16, 2013) to 3,000 flight hours or greater. The AMOC extension to inspection intervalsto 3,000 flight hours or greater was granted based on a fault tree analysis that assumed the engine cowl anti-ice system was causing the short flexshaft to fail. We now have enough data to invalidate that assumption. As part of the certification process of the new flexshaft, the system safety analyses on all Model 747 and Model 767 airplanes with GE CF6-80C2 engines were refined, and the predicted failure rate from the comparative testing was used. We have determined that we could meet average and specific risk requirements with an inspection interval of 2,000 flight hours for both the CDU cone brake and TRAS lock flexshaft. Therefore, we have determined that a repetitive inspection interval of 2,000 flight hours is necessary to address the unsafe condition. We have not changed this final rule in this regard. \n\nRequest To Combine Multiple ADs Into One AD \n\n\n\tANZ requested that we combine the following ADs into one new AD to reduce the complexity of multiple regulatory requirements. \n\tAD 2003-16-16, Amendment 39-13269 (68 FR 51439, August 27, 2003). \n\tAD 2000-15-04, Amendment 39-11833 (65 FR 47252, August 2, 2000). \n\tAD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000). \n\tWe partially agree with the commenter's request. We agree with the commenter about the complexity of complying with multiple regulatory requirements. We disagree with the request to combine the requirements of these ADs into one new AD, because this final rule is not the proper venue for addressing this issue. We are issuing this final rule to require replacement of the short flexshaft with a better and more reliable part. We have considered the previous rulemaking by allowing this new part replacement and repetitive inspections to be a terminating action for the repetitive inspections set by previous ADs, as specified in paragraph (j) of this final rule. We have not changed this final rule in this regard. \n\nRequest To Add Airplanes to the Applicability \n\n\n\tBoeing requested that we include Model 767 airplanes powered by GE CF6-80C2 engines in the applicability of the NPRM (78 FR 3363, January 16, 2013); and require all production airplanes to do the requirements of paragraph (h) of the NPRM. Boeing stated that AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 5, 2000), which is applicable to Model 767 airplanes powered by GE CF6-80C2 engines, mandates the inspection of the TRAS lock flexshaft and CDU cone brake at 1,000 hours, and that these airplanes should be able to use the extended 2,000-hour TRAS lock flexshaft and CDU tests granted in the NPRM. \n\tWe disagree with the commenter's request. Adding airplanes to the applicability would necessitate (under the provisions of the Administrative Procedure Act) reissuing the notice, reopening the comment period, considering additional comments subsequently received, and eventually issuing a final rule. In consideration of the amount of time that has already elapsed since issuance of the original notice (78 FR3363, January 16, 2013), we have determined that further delay of this final rule is not appropriate. However, we might consider further rulemaking on this issue. We have not changed this final rule in this regard. \n\nRequest To Allow Dispatch of an Airplane With a Failed CDU Cone Brake Check \n\n\n\tBoeing requested that we allow a master minimum equipment list (MMEL) dispatch of an airplane when a CDU cone brake check fails. Boeing stated that a certain FAA AMOC approval letter already allows for an MMEL dispatch of an airplane when only the CDU cone brake check fails. \n\tWe agree with the commenter's request. The electro-mechanical brake provides an additional level of protection against the inadvertent in- flight deployment of the thrust reverser. We have added new paragraph (l) to this final rule, which specifies that in the event of a CDU cone brake failure, an airplane may be operated as specified in the operator's FAA-approved minimum equipment list, provided that certain conditions are met. We have redesignated subsequent paragraphs accordingly. \n\nRequests for Terminating Action \n\n\n\tBoeing requested we specify that the functional tests in paragraph (h) of the NPRM (78 FR 3363, January 16, 2013) terminate the functional test requirements of paragraph (e), as well as paragraph (f), of AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000). \n\tDelta Airlines requested we specify that the functional tests in paragraph (h) of the NPRM (78 FR 3363, January 16, 2013) terminate the requirements of paragraph (a), as well as paragraph (e), of AD 2003-16- 16, Amendment 39-13269 (68 FR 51439, August 27, 2003). \n\tWe agree with the commenters' requests. The functional tests required by paragraph (h) of this final rule address the tests required by the AD requirements cited by the commenters. We have changed paragraphs (j)(1) and (j)(3) of this final rule, as specified by the commenter. \n\nRequest for Credit for Previous Actions \n\n\n\tAtlas Air requested that we give credit for the actions required by paragraph (h) of the NPRM (78 FR 3363, January 16, 2013), if those actions were done before the effective date of this AD using the service information specified in paragraph (h) of the NPRM. \n\tSpecifying credit for the actions done before the effective date of this final rule using the same service information specified in paragraph (h) of this final rule is unnecessary. Paragraph (f) of this final rule specifies to comply with the AD within the compliance times specified, unless already done. We have not changed this final rule in this regard. \n\nRequests for Clarification of Installation Instructions \n\n\n\tAmerican Airlines (AAL) requested that we revise paragraph (g) of the NPRM (78 FR 3363, January 16, 2013) to clarify that the installation instructions for the new short flexshaft contain a lower torque value than the torque value specified in AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000), and the service informationreferenced in AD 2000-09-04. \n\tWe agree to clarify the installation instructions. The torque value for the new short flexshaft installation in paragraph (g) is lower than the torque value described for the part specified in AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000). We have \n\n((Page 15663)) \n\nadded Note 1 to paragraph (g) of this final rule to clarify this issue. \n\nRequest for Clarification of Compliance Time \n\n\n\tAAL requested we clarify that the compliance time of paragraph (h) of the NPRM (78 FR 3363, January 16, 2013) supersedes the compliance times specified in AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000); Boeing Service Bulletin 767-78A0081, Revision 2, dated April 19, 2001; and FAA AMOC 140S-03-313, dated December 19, 2003. \n\tWe agree to clarify the compliance time. This final rule does not supersede AD 2000-09-04, Amendment 39-11712 (65 FR 25833, May 4, 2000). FAA AMOC 140S-03-313, dated December 19, 2003, applies to AD 2000-09- 04,and not to this final rule. We have determined that the functional test compliance times specified in paragraph (h) of this final rule are necessary to ensure the continued airworthiness of the airplane. Under the provisions of paragraph (n) of this final rule, however, we may consider requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. We have not changed this final rule in this regard. \n\nRequest for Certain Hardware Approvals \n\n\n\tAAL requested that we approve FAA AMOC 140S-12-42, dated March 14, 2012, as an AMOC to the NPRM (78 FR 3363, January 16, 2013), or specifically list the hardware approvals and actions in AMOC 140S-12-42 dated March 14, 2012, in the NPRM. \n\tWe disagree with the commenter's requests. The commenter did not provide data to substantiate that the hardware actions specified in FAA AMOC 140S-12-42, dated March 14, 2012, are applicable to the new short flexshaft installation required by this final rule. Under the provisions of paragraph (n) of this final rule, however, we will consider requests for approval of an AMOC if sufficient data are submitted to substantiate that alternative hardware requirements would provide an acceptable level of safety. We have not changed this final rule in this regard. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this AD with the changes described previously and minor editorial changes. We have determined that these minor changes: \n\tAre consistent with the intent that was proposed in the NPRM (78 FR 3363, January 16, 2013) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM (78 FR 3363, January 16, 2013). \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scopeof this AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 298 airplanes of U.S. registry. \n\tWe estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tAction Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Replacement Model 747 airplanes.... 8 work-hours x $85 per hour $32,248 $32,928 $2,370,816 (72 airplanes)..................... = $680. Replacement Model 767 airplanes.... 4 work-hours x $85 per hour 16,124 16,464 3,720,864 (226 airplanes).................... = $340. Functional test.................... 12 work-hours x $85 per 0 1,020 73,440 Model 747 airplanes................ hour = $1,020. (72 airplanes)..................... Functional test.................... 12 work-hours x $85 per 0 1,020 230,520 Model 767 airplanes................ hour = $1,020. (226 airplanes).................... ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this AD. \n\nAuthority for This Rulemaking \n\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 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\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), \n\t(3) Will not affectintrastate aviation in Alaska, and \n\t(4) 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\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.