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 supersedes AD 2001-20-12, amendment 39- 12460 (66 FR 52492, October 16, 2001). The existing AD applies to certain Boeing Model 757 series airplanes. That NPRM was published in the Federal Register on December 8, 2005 (70 FR 72939). That NPRM proposed to require incorporating a new revision to the Airworthiness Limitations section of the Instructions of Continued Airworthiness to mandate certain repetitive inspections for fatigue cracking of principal structural elements (PSEs). That NPRM also proposed to add airplanes to the applicability in the existing AD. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments that have been received on the NPRM. \n\nSupport for NPRM \n\n\tAmerican Airlines states that it will comply with the requirements in the NPRM and has no objection or additional comments. \n\n\tUnited Airlines concurs with the contents of the NPRM, and adds that it plans to comply with the June 2005 revision of the Boeing 757 Maintenance Planning Data (MPD) Document and will update its documents to incorporate that revision. \n\nRequest To Change Applicability \n\n\tBoeing asks that we add Model 757-200CB series airplanes to the applicability specified in the NPRM. Boeing states that Model 757-200CB is listed on Type Certificate Data Sheet A2NM, Revision 24, dated May 16, 2005. \n\n\tWe agree with Boeing as this AD is applicable to all Boeing Model 757 airplanes. We find that this change does not expand the scope of the NPRM because no additional U.S. airplanes will be affected by this AD as a result of this change. We have added Model 757-200CB series airplanes to the applicability section of this AD accordingly. \n\nRequest for Credit for Previous/Later Approved MPD Revisions \n\n\tContinental Airlines (CAL) recommends that paragraph (h) of the NPRM mandate incorporation of Revision "May 2003" or later FAA- approved revisions of Boeing Document D622N001-9, instead of Revision "June 2005." CAL states that Revision "June 2005" only incorporated a minor escalation of the time interval to a certain MPD item. The item is related to the operational check of the right Engine Indication And Crew Alerting System (EICAS) computer and has no bearing on any PSE. CAL adds that a review of the Revision "July 2004" changes showed minor typographical errors being corrected on certain MPD items. These items relate tothe operational check of the decompression panel of the flight deck door, and have no relation to any PSE. CAL notes that it is Revision "May 2003" that incorporates significant changes to the Airworthiness Limitations--Structural Inspections. \n\n\tCAL also states that, since the release of AD 2001-20-12, Boeing Document D622N001-9 has been revised seven times. Since that AD mandated the use of Revision "May 1997" or Revision "November 1998" only, an alternative method of compliance (AMOC) to the AD which was issued by the Seattle Aircraft Certification Office (ACO) was required in order to incorporate a later FAA-approved revision of the Boeing Document. CAL adds that the AMOC requirement did not provide any added value, since only the Seattle ACO is allowed to revise the Airworthiness Limitations--Structural Inspections. CAL also refers to approval of later FAA-approved revisions through an AMOC they received for AD 2001-20-12. \n\n\tWe partially agree with CAL as follows: \n\n\tAs policy, we do not reference "later-approved" service information in ADs. Using the phrase "or later FAA-approved revisions" violates Office of the Federal Register regulations for approving materials that are incorporated by reference. However, affected operators may request approval to use a later revision of the referenced MPD Document as an AMOC under the provisions of paragraph (j) of this AD. In addition, as specified in paragraph (j)(1) of this AD, AMOCs approved previously in accordance with AD 2001-20-12 are approved as AMOCs for the corresponding provisions of this AD. \n\n\tWe do not agree to replace Boeing 757 MPD Document, Section 9, "Airworthiness Limitations and CMRs," Subsection B., of Boeing Document D622N001-9, Revision "June 2005" with Revision "May 2003." However, since Revision "May 2003" includes all significant changes that are in Revision "June 2005," we have added Revision "May 2003" to paragraph (h) of this AD as an acceptable method of compliance for revising theMPD. \n\nRevise Paragraph (f) of the NPRM \n\n\tUS Airways asks that the language specified in paragraph (f) of the NPRM be changed to require that operators incorporate the changes to Boeing 757 MPD Document, Section 9, "Airworthiness Limitations and CMRs," Subsection B., of Boeing Document D622N001-9, Revision "May 1997" or Revision "November 1998." U.S. Airways states that, operators cannot revise the MPD Document specified in paragraph (f), only Boeing can make such revisions with FAA approval. U.S. Airways states that, as an operator, they can only incorporate the changes into their Boeing 757 maintenance program to comply with the published requirements of the subject MPD Document Airworthiness Limitations. \n\n\tWe do not agree with U.S. Airways. The airworthiness limitations, like the operating limitations, are a part of the type certificate for an airplane. Once an airworthiness certificate is issued for an airplane certifying that it conforms to an approved type design, this design is "locked" in the sense that the manufacturer cannot unilaterally change it for the subject airplane. Therefore, when the manufacturer makes any subsequent changes to the type certificate, including changes to the operating or airworthiness limitations, those changes are legally required only for products that are submitted for airworthiness certification based on a showing of conformity to the later design. \n\n\tThus, for many years, we have imposed operating restrictions that are necessary to address identified unsafe conditions by requiring revisions to the operating limitations section of the Airplane Flight Manual (AFM). (Revision of the AFM by the type certificate holder would be effective only for airplanes produced after that revision.) Similarly, Boeing's revision to the ALI was effective only for airplanes later certificated with those revisions included in their type certificate. For this reason, as stated in the NPRM, we must engage in rulemaking (i.e., issuance of anAD), in order to make the revisions mandatory for previously certificated airplanes. \n\n\tWhile the ALIs are contained in a "Boeing document" in the sense that Boeing originally produced it, the document, nevertheless, is a part of the instructions for continued airworthiness that operators must use to maintain the airplane properly. As explained in the NPRM, the effect of requiring that the document be revised to incorporate the current version of the ALI is that, in accordance with 14 CFR part 91.403(c), operators are then required to comply with those limitations. This is analogous to the effect of requiring a revision to the operating limitations: In accordance with 14 CFR part 91.9(a), operators are required to comply with the revised operating limitations. \n\n\tOf course, those operators that have previously revised the ALI (or incorporated the revision into their maintenance programs) are given credit for having previously accomplished the requirements of this AD, as allowed by paragraph (e) of this AD. The legal effect is the same: The operator is required to comply with the limitations per 14 CFR part 91.403(c). We have made no change to the AD in this regard. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been received, and determined that air safety and the public interest require adopting the AD with the changes described previously. 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 673 airplanes of U.S. registry. \n\n\tThe actions that are required by AD 2001-20-12, and retained in this AD, take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the currently required actions is $65 per airplane. \n\n\tThe new actions take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the new actions specified in this AD for U.S. operators is $43,745, or $65 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 removing amendment 39-12460 (66 FR 52492, October 16, 2001) and by adding the following new airworthiness directive (AD):