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 certain Boeing Model 737-300, 737-400, 737-500, 737-600, 737-700, 737-800, 757-200, 757-200PF, 757-200CB, and 757-300 series airplanes was published in the Federal Register on December 29, 2000 (65 FR 82957). That action proposed to require a test of the two electrical circuits that close the fuel shutoff valve on the wing spar, and repair, if necessary. \n\nExplanation of New Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Service Bulletin 737-28-1164, Revision 1, dated May 10, 2001, which describes procedures for a one-time test of the two electrical circuits that close the fuel shutoff valve on each wing spar to determine if there is continuity, and location and repair of any discontinuity. The procedures described in Revision 1 of the service bulletin are essentially similar to those described in the original issue of the service bulletin, dated August 24, 2000, which was listed in the proposed rule as the appropriate source of service information for Boeing Model 737-300, 737-400, and 737-500 series airplanes. Revision 1 merely corrects the location of two electrical connectors. Accomplishment of the actions specified in Revision 1 of the service bulletin is intended to adequately address the identified unsafe condition. \n\n\tIn consideration of this new service information, the FAA has revised paragraph (a) of this final rule to refer to Boeing Service Bulletin 737-28-1164, Revision 1, in addition to the original issue of the service bulletin, as an acceptable source of service information for accomplishment of paragraph (a) on Boeing Model 737-300, -400, and -500 series airplanes. \n\nComments \n\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\nSupport for the Proposal \n\n\tTwo commenters support the proposed rule. \n\nProvide Credit for Use of Telexes \n\n\tOne commenter requests that the FAA revise the proposed AD to give credit for accomplishment of the proposed actions using the following telexes: \n\n\tBoeing All Base Telex M-7200-00-01064, dated April 24, 2000 \n\n\tBoeing Telex SWA-DAL-00-00182H, dated March 27, 2000 \n\n\tBoeing Telex CAL-IAH-00-00681H, dated April 7, 2000 \n\n\tBoeing All Base Telex M-7200-00-01231, dated May 31, 2000 \n\n\tBoeing Telex AAL-AFW-00-00324H, dated March 27, 2000 \n\n\tThe commenter states that the instructions in these telexes are consistent with those in the service bulletins referenced in the proposed AD. The airplane manufacturer issued the telexes to provide adequate instructions to operators that wanted to perform the tests on their airplanes before the applicable service bulletins were available. \n\n\tThe FAA concurs with the commenter's request, and has added Note 3 to this AD to give credit for using the referenced telexes to accomplish the requirements of this AD before the effective date of this AD. \n\nRevise Cost Impact Estimate \n\n\tTwo commenters state that the proposed actions have already been accomplished on certain airplanes in their fleets. The FAA infers that the commenters are requesting that the FAA revise the "Cost Impact" section of the proposed AD to reflect the accomplishment of the proposed requirements on some airplanes. The FAA concurs with the commenters' request and has revised the "Cost Impact" section of this AD to reflect that some airplanes have already complied with this AD. \n\n\tOne commenter states that the test, as proposed, takes two hours. Though the commenter does not specify which airplane model its estimate applies to, the FAA infers that the commenter is requesting that the FAA increase the estimate of work hours for Model 737-300, -400, and -500 series airplanes from one to two work hours. The FAA concurs with this request, and hasrevised the "Cost Impact" section of this AD accordingly. \n\nRequest To Consider Need for Repetitive Tests \n\n\tOne commenter requests that the FAA and the airplane manufacturer review the Maintenance Planning Document for the affected airplane models to assess whether repetitive tests of the circuits subject to the proposed AD are necessary. The commenter does not request a change to the proposed rule. \n\n\tThe FAA acknowledges the commenter's concern. At this time, the Maintenance Planning Document for the Model 737 and 757 series airplanes includes only a check of the fuel shutoff valve. The procedure for this check is similar to the functional test that is performed during production of the airplane, which was described in the proposed AD, in that the test only verifies that one of the two circuits needed to supply power for the fuel shutoff valve operates correctly. The FAA and the airplane manufacturer are coordinating development of a new functional test that would verify thatboth circuits work correctly. No change to the final rule is necessary in this regard. \n\nRequest To Extend Compliance Time \n\n\tOne commenter requests that the FAA extend the compliance time from 6 months to 18 months for the test specified in the proposed AD. The commenter states that an 18-month compliance time will allow operators to perform the test in the proposed AD at a regularly scheduled maintenance interval. The commenter notes that a 6-month compliance time does not align with the provisions of Air Transport Association Specification 111, which states, "to capture the majority of scheduled maintenance periods, a nominal 'intermediate' check described by an interval of 18 months and an aircraft downtime of one-to-three days should be considered." \n\n\tThe FAA does not concur with the commenter's request. The commenter provides no technical justification for increasing the compliance time as requested. The unsafe condition addressed by this AD--inability to shut off the flow of fuel to an engine after an uncontained engine failure--is a significant safety issue, and the FAA has determined that the compliance time of 6 months, as proposed, is warranted. This decision is based on the anticipated rate of latent failures in the system. In developing an appropriate compliance time for the actions required by this AD, the FAA considered not only those safety issues, but the manufacturer's recommendations, parts availability, and the practical aspect of accomplishing the required test within an interval paralleling normal scheduled maintenance for the majority of affected operators. In light of all of these factors, the FAA considers 6 months an appropriate compliance time wherein safety will not be adversely affected. No change to the final rule is necessary in this regard. \n\nConclusion \n\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\n\tThere are approximately 3,403 Model 737-300, 737-400, 737-500, 737-600, 737-700, 737-800, 757-200, 757-200PF, 757-200CB, and 757-300 airplanes of the affected design in the worldwide fleet. \n\n\tThe FAA estimates that this AD will affect 795 Model 737-300, -400, and -500 airplanes of U.S. registry. The required test will take approximately 2 work hours, at an average labor rate of $60 per work hour. A commenter has advised the FAA that two of these U.S.-registered airplanes have already been tested according to the requirements of this AD. Therefore, based on the figures stated above, the FAA estimates the future cost impact of this AD on U.S. operators of Model 737-300, -400, and -500 series airplanes to be $95,160, or $120 per airplane. \n\n\tThe FAA estimates that this AD will affect 820 Model 737-600, 737-700, 737-800, 757-200, 757-200PF, 757-200CB, and 757-300 airplanes of U.S. registry. The required test will take approximately 3 work hours on each of these airplanes, at an average labor rate of $60 per work hour. A commenter has advised the FAA that 30 of these U.S.-registered airplanes have already been tested according to the requirements of this AD. Therefore, based on these figures, the FAA estimates the future cost impact of this AD on U.S. operators of these airplanes to be $142,200, or $180 per airplane. \n\tThe cost impact figures discussed above are based on assumptions that not all operators have yet accomplished the requirements of this AD action, and that no more operators would accomplish those actions in the future if this AD were not adopted. As explained previously, commenters have advised the FAA that some airplanes have been tested according to the requirements of this AD, and the estimated future cost impact has been reduced accordingly in thisfinal rule. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\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 small entities 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\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\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: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. 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\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: