Examining the Docket \n\n\tYou may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section. \n\nDiscussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to all Boeing Model 727 airplanes. That NPRM was published in the Federal Register on May 2, 2005 (70 FR 22618). That NPRM proposed to require a one-time inspection of the lower lobe frames of body section 43 to find open holes between stringers 17L and 17R and to record their location; repetitive high frequency eddy current (HFEC) inspections for cracks of all open holes; and related investigative and corrective actions if necessary. That NPRM also \nproposed to include an optional terminating action of installing rivets in all open tooling holes and all unused lining holes, which would terminate repetitive open-hole HFEC inspections once a hole is plugged with a rivet. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments received. \n\nRequest To Clarify the Frequency of the General Visual Inspection \n\n\tTwo commenters request that we clarify the frequency of the general visual inspection. The commenters point out that the summary of the NPRM specifies a one-time inspection, but this inspection is not clearly explained in either the preamble or the body of the NPRM. The commenters state that the general visual inspection of all body section 43 frames between stringers 17L and 17R is needed only one time to identify and record all locations of open holes, including liner attachment holes. If repeat inspectionsare needed, the record of the hole locations will indicate exactly where open holes are located. \n\n\tWe agree with the commenters. Both the NPRM and Boeing Alert Service Bulletin 727-53A0227, dated September 16, 2004 (which was cited as the applicable source of service information for the actions in the NPRM), are unclear about the frequency of the general visual inspection. The compliance table in paragraph 2.E. "Compliance" of the service bulletin states that the general visual inspection is to be repetitive. Figures 1 through 5 of the service bulletin instruct operators to record the locations of all open holes and to keep this information. We understood that, once all the open hole locations were identified and recorded, repeating the general visual inspection would not be necessary. This is not clear in the NPRM. Therefore, we have revised paragraph (g) of the final rule to clarify that the general visual inspection is a one-time inspection, and the HFEC inspection is repetitive.We have also clarified the Summary section to reflect this change. These changes do not increase the scope of the NPRM since these actions were already specified in the service bulletin and the NPRM specified to do all inspections in accordance with the service bulletin. \n\nRequest To Remove Requirement To Inspect Certain Open Holes Previously Modified \n\n\tThe commenter, the airplane manufacturer, requests that we specify that open holes used for lining attachments (liner attach holes) are not subject to the repetitive inspection requirements proposed in the NPRM if the terminating modification of AD 90-20-14, amendment 39-6730 (55 FR 37864, September 14, 1990), was accomplished for that hole. The commenter states that the proposed actions in the NPRM and the requirements of AD 90-20-14 conflict. AD 90-20-14 provides for the installation of a reinforcement angle and strap along the inner flange of the lower lobe frames in body section 43, which is terminating action for the repetitive inspections of in-use liner attach holes in that AD. The commenter states that the NPRM, as written, would require repeat inspections of all open liner attach holes, regardless of whether or not these reinforcement angles and straps are installed. The manufacturer has not received any reports of cracking at in-use liner attach holes in frames that have the reinforcements installed in accordance with AD 90-20-14, and the commenter contends that HFEC repetitive inspections are not necessary if these reinforcements are installed. The commenter also notes that the HFEC inspections specified in Boeing Alert Service Bulletin 727-53A0227 are an alternative method of compliance (AMOC) with the inspections required by paragraph A. of AD 90-20-14 and are the preferred method of inspection. \n\n\tWe partially agree with the commenter. We agree that it is not necessary to accomplish the repetitive inspections specified in paragraph (g) of the NPRM for in-use liner attach holes where the frame has been reinforced in accordance with AD 90-20-14. We agree with the commenter's technical justification. We disagree with completely eliminating all inspections of in-use liner attach holes. Boeing Service Bulletin 727-53-0068, Revision 4, dated September 14, 1989, which is cited as the applicable source of service information for the actions in AD 90-20-14, specifies post-modification inspections of the in-use liner attach holes with the frame reinforcement modification installed. We have added a new paragraph (j) and Table 1 to the final rule to specify that repetitive inspection intervals for in-use liner attach holes are extended where the frame has been reinforced in accordance with AD 90-20-14. We have re-identified subsequent paragraphs accordingly. \n\nExplanation of Additional Changes \n\n\tWe have simplified paragraph (h)(2) of the final rule by referring to paragraph (k) of the final rule for repair methods. \n\n\tWe have revised the applicability to identify model designations as published in the most recent type certificate data sheet for the affected models. \n\n\tWe have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies. \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\nCosts of Compliance \n\n\tThere are about 1,038 airplanes of the affected design in the worldwide fleet. This AD affects about 616 airplanes of U.S. registry. The inspection takes between 8 and 15 work hours per airplane per inspection cycle, depending on the configuration of the airplane. The average labor rate is $65 per work hour. Based on these figures, the estimated cost of this AD for U.S. operators is between $320,320 and $600,600, or between $520 and $975 per airplane, per inspection cycle. \n\n\tFor operators that choose to do the optional terminating action of installing rivets in all open tooling holes and all unused lining holes, the actions take between 13 and 23 work hours per airplane, depending on the configuration of the airplane. The average labor rate is $65 per work hour. Based on these figures, the estimated cost of the optional terminating action is between $845 and $1,495 per airplane. \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\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\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 Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):