Discussion \n\n\tThe FAA issued a second supplemental notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Model 737-600, -700, -700C, -800, and -900 series airplanes. That second supplemental NPRM was published in the Federal Register on March 23, 2009 (74 FR 12094). That second supplemental NPRM proposed to require sealing the fasteners on the front and rear spars inside the main fuel tank and on the lower panel of the center fuel tank, inspecting the wire bundle support installation in the equipment cooling system bays to identify the type of clamp installed and determine whether the Teflon sleeve is installed, and doing related corrective actions if necessary. \n\nRelevant Service Information \n\n\tThe second supplemental NPRM cited Boeing Alert Service Bulletin 737-57A1279, Revision 1, dated September 25, 2008, as the appropriate source of service information. Boeing has since revised the service bulletin. Boeing Service Bulletin 737-57A1279, Revision 2, dated February 2, 2010, incorporates additional data that were included in Boeing Information Notice (IN) 737-57A1279 IN 02, dated September 25, 2008; 737-57A1279 IN 03, dated October 30, 2008; and 737-57A1279 IN 04, dated March 13, 2009. This additional information does not add more work. \n\n\tBoeing has also issued IN 737-57A1279 IN 05, dated April 8, 2010. This IN specifies that Model 737-800 and -900 airplanes may have an additional clamp located at stringer 10 that requires the work shown in the steps of Figures 6, 7, 10, and 11 of Boeing Service Bulletin 737- 57A1279, Revision 2, dated February 2, 2010, in the environmental control system bay of the affected airplanes. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments received on the second supplemental NPRM. \n\nSupport for the Second Supplemental NPRM \n\n\tBoeing reviewed the second supplemental NPRM and concurred with the contents of the proposed rule. \n\nRequest To Delay AD Action \n\n\tContinental Airlines (CAL) expressed continued concern that the manufacturer needs to update the maintenance service documents to avoid inadvertently demodifying the work that this AD requires, which would result in potential enforcement action against CAL. CAL commented that to ensure compliance with the maintenance planning data Fuel System Airworthiness Limitations, the requirements of Appendix H.1(a) of the Federal Aviation Regulations (14 CFR 25); and the requirements of sections 26.1(a), 26.1(b)(2), and 26.1(b)(3) of the Federal Aviation Regulations (14 CFR 26.1(a), 14 CFR 26.1(b)(2), and 14 CFR 26.1(b)(3)); must be complied with by the original equipment manufacturer or type certificate holder. In addition, the operator must also comply with section 91.1507(e) of the Federal Aviation Regulations (14 CFR 91.1507(e)); and section 121.1113(e) of the Federal Aviation Regulations (14CFR 121.1113(e)). CAL stated that these procedures conflict with the regulations of sections 25.1529 and 25.1729 of the Federal Aviation Regulations (14 CFR 25.1529 and 25.1729) and applicable provisions of 14 CFR parts 21 and 26. \n\n\tWe acknowledge the commenter's concern. However, no new ICAs have been developed for the design change required by this AD. Operators and owners are responsible for ensuring that the configuration mandated by this AD is maintained in accordance with section 39.7 of the Federal Aviation Regulations (14 CFR 39.7). \n\n\tIf any new airworthiness limitations (AWLs) related to any of the design features mandated by this AD are developed, we may consider additional rulemaking to mandate incorporations of those AWLs into operators' maintenance programs. We have not changed the AD in regard to this issue. \n\n\tCAL cited sections 91.1507(e) of the Federal Aviation Regulations (14 CFR 91.1507(e)) and other regulations and expresses concern that the absence of theICAs could result in enforcement action. That section requires operators to include in their maintenance programs all fuel system ICAs developed under Special Federal Aviation Regulation (SFAR) 88. However, that regulation requires operators to incorporate ICAs provided by the design approval holder. Since no ICAs were developed for the required modification, operators do not violate that regulation if their maintenance programs do not yet contain ICAs for the referenced design change. However, under section 39.7 of the Federal Aviation Regulations (14 CFR 39.7), it is still the responsibility of the operators to keep their airplanes in a configuration that is in compliance with the AD. We have not changed the AD in regard to this issue. \n\n\tThe FAA is working with industry to evaluate potential changes to the AD process that are intended to more clearly identify how to maintain configurations that are required for AD compliance. \n\nRequest To Clarify Airplanes Subject to Paragraph (i) of the AD \n\n\tThe Air Transport Association (ATA), on behalf of its member American Airlines (AA), requested that we clarify the "applicability requirements'' in paragraph (i) of the second supplemental NPRM to state that modifications should be acceptable for compliance with the AD if they were made in accordance with Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007, and if the table in paragraph 1.A., "Effectivity,'' of that service bulletin was used to correctly determine which airplanes are subject to the requirements of paragraph (i) of the AD. The commenter noted that the variable numbers following the table are erroneous. \n\n\tLufthansa Technik (LTK) also requested that we revise paragraph (i) of the second supplemental NPRM. LTK requested that we consider airplanes with line numbers 571 through 1691 inclusive on which the referenced actions have been performed in accordance with Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007, to be compliant with the proposed AD. \n\tWe agree with the requests to clarify which airplanes are subject to the requirements of paragraph (i) of this final rule. We have revised paragraph (i) of this final rule to state that actions done using the group assignments by line numbers found in the table in paragraph 1.A., "Effectivity,'' and in accordance with the original service bulletin, Boeing Service Bulletin 737-57A1279, dated January 24, 2007, are acceptable for compliance with the corresponding requirements of this AD. \n\nRequest To Allow Alternative Teflon Sleeving Procedure \n\n\tThe ATA, on behalf of its member AA, proposed an alternative sleeving procedure. In its comment, AA stated that the Teflon sleeve installation cannot be accomplished as shown in Figure 13 of Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007. AA stated that Figure 9 of the service bulletin shows that the adjacent tube conduit does not allow the sleeve to be 3 inches long and centered on the clamp. AA proposed that an alternative sleeving procedure extend the sleeving at least 1 inch beyond the edge of the clamp. If 1 inch of sleeving cannot be achieved, AA suggested that the sleeving be extended as far as possible. \n\n\tWe agree that clarification may be necessary. Boeing is revising Boeing Alert Service Bulletin 737-57A1279 to address this issue. However, due to the urgency of the unsafe condition and in consideration of the amount of time that has already elapsed since issuance of the original service bulletin, we have determined that further delay of this final rule is not appropriate. We disagree with the request to allow an alternative Teflon sleeving procedure in this final rule. We do not have sufficient data that indicate this procedure provides an acceptable level of safety. If operators can provide sufficient data to indicate that an alternative Teflon sleeving procedure would provide an acceptable level of safety, operators can request approvals of AMOCs in accordancewith the requirements of paragraph (j) of this final rule. We have not changed the final rule regarding this issue. \n\nRequest To Allow Alternative Procedure To Seal Fasteners on Wing and Main Tanks \n\n\tThe ATA, on behalf of its member AA, requested that we remove the proposed requirement to reseal the fasteners if already done previously in accordance with Boeing Alert Service Bulletin 737-57A1279, dated January 24, 2007. In its comment, AA stated that sealant has been previously applied at some fastener locations in the center tank and the wing tanks during airplane assembly. Therefore, AA stated, it is not possible to accomplish the steps in Figures 14 and 15 of that service bulletin, and AA proposed that if the fasteners are sealed in accordance with that service bulletin, then no further work should be required. AA also stated that Boeing 737-57A1279 Information Notice (IN) 04, dated March 13, 2009, addresses this issue. \n\n\tWe agree with the commenter. Boeing 737-57A1279 IN 04, dated March 13, 2009, states that for fasteners that have been previously sealed to the specifications of Boeing Alert Service Bulletin 737-57A1279, it is not required for the existing seal to be removed and the fastener sealed again. Boeing Service Bulletin 737-57A1279, Revision 2, dated February 2, 2010, incorporates the information included in Boeing 737- 57A1279 IN 04, dated March 13, 2009. We updated this final rule to refer to Boeing Alert Service Bulletin 737-57A1279, Revision 2, dated February 2, 2010, as an appropriate source of service information. \n\nRequest To Reference Additional Service Information \n\n\tThe ATA, on behalf of its member AirTran Airways, requested that we approve Boeing Information Notices 03 and 04 as sources of service information for the supplemental NPRM. In its comment, AirTran Airways stated that the information notices clarify and provide corrections to Boeing Service Bulletin 737-57A1279, Revision 1, dated September 25, 2008. \n\n\tWe partially agree. We acknowledge that the information contained in these notices may be useful to operators to complete the requirements of this AD. However, Boeing has issued Boeing Service Bulletin 737-57A1279, Revision 2, dated February 2, 2010, to include the information in the information notices. We have revised the final rule accordingly. \n\nExplanation of Change 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 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\nExplanation of Change to Costs of Compliance \n\n\tSince issuance of the NPRM, we have increased the labor rate used in the Costs of Compliance from $80 per work-hour to $85 per work-hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate. \n\nCosts of Compliance \n\n\tThere are about 1,754 airplanes of the affected design in the worldwide fleet; of these, 645 airplanes are U.S.-registered. The following table provides the estimated costs for U.S. operators to comply with this final rule, at an average hourly labor rate of $85. \n\n\tEstimated Costs\n\n\nAction \nGroup \nWork hours \nCost per airplane \nNumber of U.S.-registered airplanes \nFleet cost \n\n1 \n62 \n$ 5,270 \n586 \n$ 3,088,220\n\n2 \n28 \n$ 2,380 \n44 \n$ 104,720\nSealant application \n3 \n28 \n$ 2,380 \n15 \n$ 35,700\n\n1 \n4 \n$ 340 \n586 \n$ 199,240\n\n2 \n4 \n$ 340 \n44 \n$ 14,960\nInspection \n3 \n2 \n$ 170 \n15 \n$ 2,550 \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. SubtitleI, 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 and placed it in the AD docket. 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\n\tAccordingly, 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 Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):