The FAA proposed to amend 14 CFR part 39 with an AD for certain Boeing Model 777-200 and -300 series airplanes. That action, published in the Federal Register on January 19, 2005 (70 FR 2980), proposed to require modification of the operational program software (OPS) of the air data inertial reference unit (ADIRU). \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\tOne commenter supports the proposed AD and states that it is appropriate because it will prevent future occurrences of erroneous heading information being presented to the pilot. Another commenter states that it understands the need for the modification to the affected OPS of the ADIRU and does not have any objection to the proposed AD. The second commenter adds that the modification was accomplished on all its Model 777 series airplanes in calendar year 2002. \n\nRequest To Add New Service Information \n\n\tTwo commenters ask that Boeing Service Bulletin 777-34-0094, dated June 10, 2004, be added to the proposed AD as an additional source of service information for accomplishing the modification of the OPS of the ADIRU. \n\n\tOne commenter, the airplane manufacturer, states that the new service bulletin provides procedures for installation of a newer version of the OPS of the ADIRU, which contains the fix required by the proposed AD. The commenter suggests adding the new service bulletin to paragraph (f) of the proposed AD as an option for accomplishing the modification in the proposed AD, instead of using the service bulletin currently referenced. \n\n\tAnother commenter states that it is concerned about any wording in the proposed AD that may affect and impact any future installations of new OPS of the ADIRU. The commenter adds that it is imperative that the proposed AD address this issue as Boeing has already released a new service bulletin. The commenter notes that the new service bulletin contains information for updating the existing software with an adjusted Mach function; the proposed AD would mandate installation of previous OPS of the ADIRU per Boeing Service Bulletin 777-34A0082, Revision 1, dated December 19, 2002. The commenter has already incorporated the installation of OPS of the ADIRU per the mandated bulletin, and has also incorporated the installation of OPS of the ADIRU per Service Bulletin 777-34-0094. The commenter is concerned that an Alternative Method of Compliance (AMOC) may now be required for any operator that has incorporated or will incorporate software upgrades in the future. \n\n\tWe agree with the intent of the commenters' requests to reference Boeing Service Bulletin 777-34-0094, we have reviewed the service bulletin and we determined that it addresses the unsafe condition appropriately. Therefore, we have changed paragraph (f) of this final rule to include that service bulletin as an additional appropriate source of service information for accomplishing the modification. However, regarding future upgrades of the OPS of the ADIRU per the issuance of future service information; we cannot accept as-yet unpublished service documents for compliance with the requirements of an AD. Referring to an unavailable service bulletin in an AD to allow operators to use later revisions of the referenced documents (issued after publication of the AD) violates Office of the Federal Register regulations for approving materials that are incorporated by reference. However, under the provisions of paragraph (g) of this AD, affected operators may request approval to use a later revision of the referenced service bulletin as an AMOC. \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 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 409 airplanes of the affected design in the worldwide fleet. This AD affects about 130 airplanes of U.S. registry. The actions take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Required parts are free of charge. Based on these figures, the estimated cost of the AD for U.S. operators is $8,450, or $65 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 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 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):