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 Boeing Model 747 airplanes and certain Boeing Model 757-200, - 200PF, and -300 series airplanes. That NPRM was published in the Federal Register on December 23, 2008 (73 FR 78672). That NPRM proposed to require replacing the control switches of the forward, aft, and nose cargo doors of Model 747 airplanes; and replacing the control switches of cargo doors 1 and 2 of Model 757 series airplanes. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received from the four commenters. \n\nSupport for the NPRM \n\n\tBoeing concurs with the content of the NPRM. \n\nRequest for Inclusion of Airplane Maintenance Manual (AMM) 52-34-30 \n\n\tAmerican Airlines (AA) requests that we revise paragraph (f)(2) of the NPRM to allow another method to comply with the AD for Model 757 series airplanes. As proposed, the NPRM would require replacing the control switches of cargo doors 1 and 2 of Model 757 series airplanes, in accordance with Boeing Special Attention Service Bulletin 757-52- 0090, dated September 21, 2007, which specifies a brush coat to the switch terminals with BMS5-37 or BMS5-45 Class A sealant after all wires are connected. Since AA uses the AMM for instructions for replacement, and the AMM does not specify the brush coat to the switch terminals with BMS5-37 or BMS5-45 Class A sealant after all wires are connected, AA requests that we revise the NPRM to state that the control switches of cargo doors 1 and 2 can be replaced in accordance with either the Accomplishment Instructions of Boeing Special Attention Service Bulletin 757-52-0090, dated September 21, 2007, or the removal and installation steps found in the AMM. \n\n\tAA states that it initiated a replacement program for the cargo switches mentioned in the previousparagraph in accordance with the AMM. Approximately one year after the initiation of the replacement program, Boeing released Boeing Special Attention Service Bulletin 757- 52-0090, dated September 21, 2007, which introduced the requirement to "(b)rush coat the switch terminals with BMS5-37 or BMS5-45 Class A sealant after all wires are connected.'' AA notes that this requirement was not and is not presently found in the AMM procedure. \n\n\tWe disagree with the request to allow doing the removal and installation procedures in the AMM as a method of compliance with paragraph (f)(2) of this AD. In order to address the identified unsafe condition, operators will have to do additional actions that are not found in the AMM, including the brush coat to the switch terminals with BMS5-37 or BMS5-45 Class A sealant after all wires are connected. Paragraph (g) of this AD provides operators the opportunity to request an alternative method of compliance (AMOC) for the requirements of paragraph (f)(2), if data are presented that justify the request. We have not changed the AD in this regard. \n\nRequest for Documentation \n\n\tFedEx requests that we revise the NPRM to identify the maintenance document that will be the appropriate source of service information for the immediate replacement of a toggle switch in the event an "uncommanded operation'' is found prior to the next 6-year mark (the proposed repetitive interval specified in the NPRM). \n\n\tWe partially agree. We agree that operators should replace the switch in the event of an uncommanded operation and note that Boeing Special Attention Service Bulletins 747-52-2286, dated September 28, 2007; and 757-52-0090, dated September 21, 2007; provide adequate information to accomplish switch replacement. We disagree with the request to revise this AD because this AD does not mandate replacement in the event of an uncommanded operation; this AD requires repetitive replacements within specified intervals. If operators replace the switch using another method, they may ask for approval of an AMOC if they also submit data that justify a different method and provide an adequate level of safety. We have not changed the AD in this regard. \n\nRequest for Determination of Reliability \n\n\tFedEx questions whether cargo toggle switch part number (P/N) 8837K2 or P/N MS25307-272, which is specified in paragraphs 2.C.2. of Boeing Special Attention Service Bulletin 757-52-0090, dated September 21, 2007, paragraphs 2.C.2., is more reliable. \n\n\tWe infer that the commenter would like us to permit installation of P/N 8837K2 so that it is not necessary for an operator to request approval of an AMOC in order to install P/N 8837K2. We disagree. The operator did not provide justification that P/N 8837K2 provides an equivalent level of safety. However, according to the provisions of paragraph (g) of the final rule, we may approve a request to allow a different compliance method if the request includes data that prove that the new method would provide an acceptable level of safety. \n\nRequest for Credit \n\n\tContinental Airlines requests that we revise the NPRM to provide credit for accomplishment of the AD when replacement of the affected cargo door switches is incorporated into a carrier's routine maintenance program. The commenter notes that its replacement schedule coincides with that specified in the NPRM. \n\n\tWe acknowledge the commenter's request. A replacement done in accordance with Boeing Special Attention Service Bulletin 747-52-2286, dated September 28, 2007; or 757-52-0090, dated September 21, 2007; as applicable; before the effective date of this AD is acceptable for compliance with the AD, as indicated by the phrase "unless already done'' in paragraph (e) of this AD. However, the commenter does not identify the service information used in the routine maintenance program to do the replacement. \n\n\tIf actions done previously align with the applicable Boeing service bulletin, the operator will be given credit. In addition, we may approve a request for an alternative method of compliance (AMOC) for replacement of the control switches if the request includes data that prove that the new method would provide an acceptable level of safety. We have not changed the AD in this regard. \n\nExplanation of Change to NPRM \n\n\tWe have changed the phrase "6 years'' to 72 months in paragraph (f) of this AD to provide a time frame that specifies the compliance with greater detail. \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 with the change described previously. We also determined that the change will not increase the economic burden on any operator or increase the scope of the AD. \n\nCosts of Compliance \n\n\tWe estimate that this AD affects 765 airplanes of U.S. registry. We also estimate that it takes about 2 to 3 work-hours per product to comply with this AD. The averagelabor rate is $80 per work-hour. Required parts cost about $130 to $195 per airplane. Based on these figures, we estimate the cost of this AD to U.S. operators to be up to $332,775, or between $290 and $435 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\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\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\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: