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 Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. That NPRM was published in the Federal Register on July 29, 2009 (74 FR 37657). That NPRM proposed to require replacing the engine fuel shutoff valves for the left and right main tanks. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received from the commenters. \n\nSupport for the NPRM \n\n\tBoeing concurs with the contents of the NPRM. Continental Airlines has no technical objections to the NPRM. \n\nRequest To Clarify Use of Valve Bodies \n\n\tContinental Airlines states that the NPRM affects the engine fuel shutoff valves, and paragraph (i) of the NPRM prohibits installing any valve with ITT Aerospace Controls part number 125334D-1 (Boeing part number S343T003-40) that has been removed from the spar location on any airplane in any location unless it has been modified in accordance with Boeing Service Bulletin 737-28-1272, dated October 31, 2008, to the new ITT 125334D-2 part number (Boeing part number S343T003-67). \n\tWe infer that Continental Airlines asks that we clarify whether the removed valve can be reused on airplanes in any location. We agree to provide clarification. These valves may not be used in any location on the airplane unless they have been modified in accordance with Boeing Service Bulletin 737-28-1272, dated October 31, 2008, to the new ITT 125334D-2 part number (Boeing part number S343T003-67). We have not changed the AD in this regard. \n\nRequest To Increase the Cost of Compliance \n\n\tAir Transport Association (ATA), on behalf of its member American Airlines, requests that we increase the costs of compliance to reflect 34 work-hours instead of 26 work-hours. ATA states that the ITT Aerospace Controls service bulletinincludes 4 hours for each engine fuel spar valve body. Each Boeing Model 737-600, -700, -700C, -800, - 900, and -900ER series airplane has 2 valve bodies in the engine fuel shutoff valve position. \n\tWe disagree with the request to increase the cost of compliance. Boeing Service Bulletin 737-28-1272, dated October 31, 2008, provides the option to return the valve to the supplier for modification, and therefore, the actions identified by the commenter are not mandatory. Because the additional costs cited by the ATA are optional to operators, we do not consider those costs in our determination of the cost of compliance. We have not changed the AD in this regard. \n\nRequest To Extend the Compliance Time \n\n\tATA, on behalf of its member American Airlines, requests that we extend the compliance time from 60 months to 72 months after the effective date of the AD. The commenter states that maintenance schedules may not allow for accomplishment of the required actions on all affected aircraft within the compliance time, depending on the effective date of the AD. \n\tWe disagree with the request to extend the compliance time. The 60- month compliance time was established to maintain an acceptable level of safety across the 737 fleet in consideration of the valve failure rate, consequence of the failure, and practicality of incorporating the corrective actions. The commenter has not offered rationale for extending the compliance time. In developing an appropriate compliance time for this action, we considered the urgency associated with the subject unsafe condition, the availability of required parts, and the practical aspect of accomplishing the required modification within a period of time that corresponds to the normal scheduled maintenance for most affected operators. According to the manufacturer, an ample number of required parts will be available to modify the U.S. fleet within the proposed compliance time. However, according to the provisions of paragraph (j) of thefinal rule, we may approve requests to adjust the compliance time if the request includes data that prove the new compliance time would provide an acceptable level of safety. We have not changed the AD in this regard. \n\nExplanation of Changes Made to This AD \n\n\tWe have revised this AD to identify the legal name of the manufacturer as published in the most recent type certificate data sheet for the affected airplane models. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCosts of Compliance \n\n\tWe estimate that this AD affects 883 airplanes of U.S. registry. We also estimate that it takes 26 work-hours per product to comply with this AD. The average labor rate is $80per work-hour. Required parts cost up to $8,496 per product. Based on these figures, we estimate the cost of this AD to the U.S. operators to be up to $9,338,608, or $10,576 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: