Discussion \n\n\tWe issued a supplemental notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Boeing Model 757-200 and 757-300 series airplanes. That supplemental NPRM was published in the Federal Register on April 8, 2008 (73 FR 19015). That supplemental NPRM proposed to require installing a bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain masts. For certain airplanes, that supplemental NPRM also proposed to require inspecting existing aft bonding jumper assemblies that might be too short, repair if necessary, and replacing the bonding jumper assembly with a new, longer bonding jumper assembly if necessary. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received. \n\nSupport for the AD \n\n\tBoeing concurs with the contents of the supplemental NPRM.Continental Airlines has no objection to the supplemental NPRM. Northwest Airlines (NWA) is in general concurrence with the modification requirements and concurs with the 60-month compliance time. The Air Transport Association (ATA), on behalf of member airlines, states that its members agree with the intent of the NPRM. \n\nRequest To Have Service Information Revised \n\n\tAmerican Airlines (AAL) requests that Boeing Special Attention Service Bulletin 757-30-0024, Revision 1, dated October 25, 2007, be revised to change the pilot hole dimensions in Figure 2, Sheet 2. (We referred to Boeing Special Attention Service Bulletin 757-30-0024, Revision 1, dated October 25, 2007, as the appropriate source of service information for the proposed actions in the NPRM.) AAL points out that the new bracket is provided without pilot holes, but the service bulletin specifies the hole location: "Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus or minus 0.03 inch.'' AAL is concerned that it may be an unreasonable expectation, within the on-aircraft environment in which the work is being performed, to locate the holes in the bracket to within 0.03 inch of the specified location. Therefore, AAL recommends that the service bulletin be revised to change the hole location dimensions to be "0.43 minimum.'' As a supporting argument for this change, AAL points out that the new grounding bracket is installed in a different location to meet the same intent for the forward drain mast and does not include dimensional location information, which AAL believes implies that the hole location in the bracket is not critical to meeting the intent of the service bulletin. \n\tWhile we do agree that the on-airplane environment can sometimes be a difficult place to work, we disagree that the service bulletin should be revised as requested by AAL. Boeing has pointed out that the edge margin requirement for the fasteners on the bonding bracket is not as critical as the placement of the fastener through stringer S-25 right. This fastener location must be drilled to within 0.35 inch, plus or minus 0.03 inch, from the top edge of the stringer on the airplane. If it is possible to maintain this drawing requirement for on-airplane installation, it should also be possible to maintain the edge margin requirements for the bonding bracket. We have confirmed that Boeing has no plans to revise the service bulletin to change the pilot hole dimensions in Figure 2, Sheet 2. We have not changed the AD in this regard. \n\nRequest To Revise the Costs of Compliance \n\n\tThe ATA, on behalf of NWA, requests that we revise the proposed Costs of Compliance provided in the supplemental NPRM. NWA states that Boeing Special Attention Service Bulletin 757-30-0024, Revision 1, dated October 25, 2007, estimates 5.35 work-hours to do the proposed modification. NWA considers this estimate to be low because of the limited access to the area to be modified. Further, NWA notes that the cost estimate provided in the supplemental NPRM reduced the work-hour estimate to only 2 work-hours. Therefore, NWA believes that we have underestimated the costs of compliance imposed on operators. \n\tWe do not agree to revise the proposed work-hour estimate. The work-hour estimate of 5.35 pointed out by NWA includes time necessary for access and close. 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 (2) necessary to do the required actions. This number represents the time necessary to perform only the actions actually required by this AD. \n\tWe 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 not changed 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 as proposed. \n\nCosts of Compliance \n\n\tThere are about 83 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD. \n\n\tEstimated Costs\n\n\nAction\nWork hours\nAverage labor rate per hour\nParts\nCost per airplane\nNumber of U.S.-registered airplanes\nFleet cost\nBonding jumper installation\n2\n$80\n1$392\n$944\n70\n$66,080\nInspection of existing bonding jumper installation in bulk cargo compartment\n1\n$80\n$392\n$472\nUp to 70\nUp to $33,040\n\n1 Per kit (1 kit per drain mast). \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\n 2. The FAA amends Sec. 39.13 by adding the following new AD: