Discussion \n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain McDonnell Douglas Model 717-200 airplanes. That NPRM was published in the Federal Register on April 7, 2008 (73 FR 18725). That NPRM proposed to require inspecting the drive assembly of the aft elevator standby loop for interference between the clevis and bolt of the bellcrank assembly, correct orientation of the pull-pull cable clevis bolt, and excessive freeplay of the bellcrank assembly bearing, and corrective actions if necessary. That NPRM also proposed to require modifying the pull-pull cable clevis in the drive assembly of the aft elevator standby loop for certain airplanes. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received. \n\nRequest To Change Summary Section for Clarification \n\n\tBoeing asks that the second sentence of the Summary section in the NPRM, which describes what is to be inspected, be changed as follows: "This proposed AD would require inspecting the aft elevator standby loop drive assembly of the elevator standby cable system for interference between the clevis and bolt of this bellcrank assembly, correct orientation of the pull-pull cable clevis bolt, and excessive freeplay of the bellcrank assembly bearing, and corrective actions if necessary.'' Boeing states that this would more accurately describe the drive assembly being inspected since there are two drive assemblies in the elevator standby cable system. \n\n\tWe agree that the description in the Summary section of the AD should be clarified. Therefore, we have changed the Summary section and all other \nrelevant sections in the AD to meet the commenter's intent. \n\nRequests To Extend Compliance Time \n\n\tMidwest Airlines asks that the compliance time in the NPRM be changed to one of the following: "Complete the inspection and modification within 27 months of the effective date of the AD,'' or "Complete the inspection and modification within 3,000 flight hours or 27 months, whichever occurs later from the effective date of the AD.'' Midwest Airlines states that it currently has a utilization of 3,450 flight hours per year, and if the compliance time is not changed, it would require compliance for all its airplanes in less than one year. Midwest Airlines also states that it checked some of its airplanes for the interference and none was found. \n\tAir Tran proposes that the inspection and clevis replacement specified in the NPRM be done concurrently at 27 months after the effective date of the AD, rather than the inspection being limited to 3,000 flight hours. Air Tran states that since similar access is required for both the inspection and clevis replacement, it is more practical to accomplish the clevis replacement at the same time as the inspection. Twenty-seven months aligns with the Model 717 maintenance program heavy maintenance visits, but 3,000 flight hours does not. \n\tWe agree to extend the compliance time for performing the inspection for the reasons provided by the commenters. We have determined that a compliance time of within 3,000 flight hours or 27 months after the effective date of the AD, whichever occurs later, is appropriate and will ensure an acceptable level of safety. We have changed paragraph (f)(1) of this AD accordingly. The compliance time for doing the clevis modification specified in paragraph (f)(2) of this AD remains the same. Changing the compliance time for the inspection provides the opportunity to do the inspection and modification at the same time. \n\nRequest To Change Cost Section \n\n\tMidwest Airlines states that the work-hour estimate specified in the Costs of Compliance section of the NPRM is underestimated. Midwest Airlines notes that the NPRM specifies 1 work-hour for the inspection and the referenced service bulletin specifies 2.4 to 11.9 work hours. Midwest Airlines adds that the NPRM specifies 4 work-hours for the modification and the referenced service bulletin specifies 5.4 work- hours. Midwest Airlines believes the service bulletin is more accurate than the NPRM. \n\tFrom this comment, we infer that Midwest Airlines would like us to increase the work-hour estimate given in the NPRM. We do not agree. The cost information below describes only the direct costs of the specific actions required by this AD. Based on the best data available, the manufacturer provided the number of work hours (1 for the inspection, 4 for the modification) necessary to do the required actions, as specified in the service bulletin. We recognize that, in doing the actions required by an AD, operators might incur incidental costs in addition to the direct costs. The cost analysis in AD rulemaking actions, however, typically does not include incidental costs such as the time required to gain access and close up, time necessary for planning, or time necessitated by other administrative actions. Those incidental costs, which might vary significantly among operators, are almost impossible to calculate. We have made no change to the AD in this regard. \n\nConclusion \n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We also determined that these changes will not increase the economic burden on any operator or increase the scope of the AD. \n\nCosts of Compliance \n\n\tWe estimate that this AD will affect 123 airplanes of U.S. registry. \n\tIt will take about 1 work-hour per product to do the inspection. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of the inspection required by this AD to the U.S. operators to be $9,840, or $80 per product. \n\tIt will take about 4 work-hours per product to do the modification. Required parts will cost about $163 per product. Based on these figures, we estimate the cost of the modification required by this AD to the U.S. operators to be $59,409, or $483 per product. \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 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\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 AD Docket. \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 AD: