A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Boeing Model 777 series airplanes was published in the Federal Register on August 20, 1999 (64 FR 45476). That action proposed to require the replacement of fuse pins in the attachment fittings and support fittings of the main landing gear with new, improved fuse pins.\n\nComments\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nRequest to Correct Error in Statement of Unsafe Condition\n\tOne commenter states that the unsafe condition, as stated in the notice of proposed rulemaking (NPRM), is incorrect, and requests that it be corrected. The NPRM states that fracture of the fuse pins could result in collapse of the main landing gear and the loss of the inboard flap and outboard spoilers. The commenter states that the inboard spoilers, not the outboard, could be lost. The FAA concurs with the commenter's request and its rationale and has revised this final rule accordingly.\n\nRequest to Reference New Service Information\n\tOne commenter requests that the NPRM be revised to reference Boeing Service Bulletin 777-57A0029, Revision 1, dated August 12, 1999, as the source of service information for the accomplishment of the actions required by this AD. (The NPRM references Boeing Alert Service Bulletin 777-57A0029, dated December 22, 1998, as the appropriate source of service information.)\n\tThe FAA concurs with the commenter's request. Since the issuance of the NPRM, the FAA has reviewed and approved Boeing Service Bulletin 777-57A0029, Revision 1. The FAA has determined that Revision 1 of the service bulletin adds no new requirements, but provides clarification of some instructions, which will assist operators in accomplishing the requirements of this AD. Therefore, the FAAhas revised paragraph (a) of the final rule to reference Boeing Service Bulletin 777-57A0029, Revision 1, in addition to the original issue of Boeing Alert Service Bulletin 777-57A0029, as appropriate sources of service information.\n\tIn addition, the FAA finds that Revision 1 of the service bulletin eliminates one airplane from the effectivity listing. (The intent of the service bulletin was accomplished on that airplane during production.)\tTherefore, the applicability of this final rule has been revised to state that this AD is applicable to airplanes listed in Boeing Service Bulletin 777-57A0029, Revision 1, rather than airplanes listed in the original issue of Boeing Alert Service Bulletin 777-57A0029 (as proposed in the NPRM). The FAA finds that this revision does not necessitate reopening the comment period, because it is relieving in nature (the change reduces the applicability of this AD by one airplane). Also, one airplane has been subtracted from the number of affected airplanes in the worldwide fleet, as stated in the cost impact section of the preamble of this final rule. \n\nRequest to Revise Compliance Time\n\tOne commenter requests that the FAA revise the compliance threshold of this AD from 48 months since date of manufacture to 1,500 days since the delivery date of the airplane. The commenter states that 1,500 days would better align with operators' scheduled maintenance intervals. The commenter also states that "'date of manufacture' is ill-defined."\n\tThe FAA does not concur with the commenter's requests. The FAA finds that there is no technical justification for changing the threshold from 48 months to 1,500 days, as the commenter requests. In developing an appropriate compliance time for this AD, the FAA considered not only the manufacturer's recommendation in the service bulletin, but the degree of urgency associated with addressing the subject unsafe condition. The FAA finds a compliance time of 48 months since date of manufacture or 18 months after the effective date of the AD, whichever occurs later, for initiating the required actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety. In addition, the FAA points out that the compliance time proposed in the NPRM is essentially the same as that recommended by the manufacturer in the service bulletin (48 months after delivery or 18 months after receipt of the service bulletin, whichever is later). With regard to referring to the delivery date of the airplane, rather than the date of manufacture, the FAA finds that there is no technical justification for such a change. The FAA refers to "date of manufacture" rather than "delivery date" of an airplane because the airplane may not be "delivered" until long after it is manufactured. Also, the date of manufacture can be readily discovered through the serial number of the airplane. No change to the final rule is necessary in this regard.\n\nConclusion\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.\n\nCost Impact\n\tThere are approximately 162 Model 777 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 34 airplanes of U.S. registry will be affected by this AD, that it will take between 5 and 39 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost between $3,090 and $8,710 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be between $3,390 and $11,050 per airplane.\n\tThe cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. \n\nRegulatory Impact\n\tThe regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of smallentities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."\n\nList of Subjects in 14 CFR Part 39\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\nAdoption of the Amendment \n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \nPART 39 - AIRWORTHINESS DIRECTIVES\n\t1. The authority citation for part 39 continues to read as follows:\nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n§ 39.13 (Amended)\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: