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 727 and Model 737 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on March 30, 1995 (60 FR 16388). That action proposed to require replacement of the actuator of the engine fuel shutoff valve and the fuel system crossfeed valve with an improved actuator. \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\n\tOne commenter supports the proposed rule. \n\n\tOne commenter notes that the description of what prompted the proposal that appeared in the Summary and Discussion sections of the preamble to the notice refers to "during ground acceptance tests." This commenter states that the problem has only been seen "during laboratory tests;" therefore, this commenter suggests that the proposal be revised accordingly. The FAA acknowledges that the commenter's wording is more accurate. The pertinent wording in the preamble to the final rule has been revised to reflect this change.\n \n\tThis same commenter requests that the FAA revise paragraph (a) of the proposed rule to reference part number 3715-7 by General Design in addition to P/N 40574-4 as an alternative method of compliance. The FAA does not concur, since the commenter provided no design or service history data for this particular actuator. However, paragraph (b) of this AD allows an operator to elect to provide such data in a request for an alternative method of compliance with the rule. \n\n\tFurthermore, this same commenter requests that the applicability of the proposal be revised to only reflect the vendor of the parts, J.C. Carter, instead of Boeing. This commenter contends that the primary responsibility for tracking AD incorporation should be with the vendor, since airplane effectivity is not identified in either the NPRM or in J.C. Carter Service Bulletin 61163-28- 08, dated December 2, 1994. The FAA does not concur. The FAA's general policy is that, when an unsafe condition results from the installation of an appliance or other item that is installed in only certain makes and models of aircraft, the AD is issued so that it is applicable to the aircraft, rather than the item. The FAA finds that making the AD applicable to the airplane model on which the item is installed ensures that operators of those airplanes will be notified directly of the unsafe condition and the action required to correct it. While it is assumed that an operator will know the models of airplanes that it operates, there is a potential that the operator will not know or be aware of specific items that are installed on its airplanes. Therefore, calling out the airplane model as the subject of the AD prevents "unknowing non-compliance" on thepart of the operator. The FAA recognizes that there are situations when an unsafe condition exists in an item that is installed in many aircraft; in fact, many times, the exact models and numbers of aircraft on which the item is installed may not be known. Therefore, in those situations, the AD is issued so that it is applicable to the item; furthermore, those AD's usually indicate that the item is known to be installed on, but not limited to, various aircraft models. \n\n\tSeveral commenters request that the compliance time for accomplishment of the replacement be extended from the proposed 24 months to 36 months. These commenters state that such an extension will allow operators to accomplish the replacement during a regularly schedules heavy maintenance visit. One of these commenters states that it would have to procure additional parts, and would need to special schedule its fleet of airplanes to accomplish this replacement within the proposed compliance time. This would entailconsiderable expense over what was estimated in the FAA's cost impact analysis. This commenter indicates that a compliance time of 36 months would allow the replacement to be accomplished during regularly scheduled maintenance, thereby eliminating any additional expenses. The FAA concurs. The FAA finds that extending the compliance time to 36 months will not adversely affect safety, and will allow the replacement to be performed using modified parts rather than newly purchased parts. Paragraph (a) of the final rule has been revised to specify a compliance time of 36 months. \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\n\tThere are approximately 4,137 Model 727 and Model 737series airplanes of the affected design in the worldwide fleet. The FAA estimates that 2,190 airplanes of U.S. registry will be affected by this AD, that it will take approximately 3 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be supplied by J.C. Carter Company at no cost to the operators. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $394,200, or $180 per airplane. \n\n\tThe total 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\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 ofgovernment. 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\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\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1.\tThe authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. § 39.13 - (Amended) \n\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: