AD 2009-01-02

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes. This AD requires a one-time general visual inspection of frames between body station (BS) 360 and BS 907 to determine if certain support brackets of the air conditioning (A/C) outlet extrusions are installed; medium- and high-frequency eddy current inspections for cracking of the frames around the attachment holes of the subject brackets; and repair if necessary. This AD also requires installing new, improved fittings for all support brackets of the A/C outlet extrusions between BS 360 and BS 907. This AD results from numerous reports of multiple cracks in the frames around the attachment holes of certain support brackets of the A/C outlet extrusions. We are issuing this AD to prevent frame cracking, which, if not corrected, could lead to a severed frame that, combined with cracking of the skin lap splice above stringer 10, could result in rapiddecompression of the airplane.

Final rule.

2009-01-02 Boeing: Amendment 39-15780. Docket No. FAA-2007-28283; Directorate Identifier 2006-NM-254-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective February 27, 2009. \n\nAffected ADs \n\n\t(b) None. \n\nApplicability \n\n\t(c) This AD applies to Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes; certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. \n\nUnsafe Condition \n\n\t(d) This AD results from numerous reports of multiple cracks in the frame around the attachment holes of the support bracket of the air conditioning (A/C) outlet extrusion. We are issuing this AD to prevent frame cracking, which, if not corrected, could lead to a severed frame that, combined with cracking of the skin lap splice above stringer 10, could result in rapid decompression of the airplane. \n\nCompliance \n\n\t(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. \n\nInspections \n\n\t(f) Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, except as required by paragraph (h) of this AD: Do a general visual inspection to determine if the support brackets of the A/C outlet extrusions between body station (BS) 360 and BS 907 have two-rivet attachment fittings in accordance with Part 2 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25- 1544, Revision 1, dated January 16, 2008 ("the service bulletin''), except at the locations identified in the notes of Step 3.B.1 of Part 1 of the Accomplishment Instructions of the service bulletin. \n\t(1) For any support bracket attached with three or more rivets: No further action is required by paragraph (f) of this AD. \n\t(2) For any subject support bracket having a two-rivet attachment fitting: Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, except as required by paragraph (h) of this AD, do medium- and high-frequency eddy current inspections for cracking of the frame around the attachment holes of the support bracket, in accordance with Part 2 of the Accomplishment Instructions of the service bulletin. If any cracking is discovered, before further flight, repair the cracking in accordance with Part 3 of the Accomplishment Instructions of the service bulletin. \n\nModification \n\n\t(g) Except as required by paragraph (h) of this AD: Before the accumulation of 36,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, replace the support fittings of all A/C outlet extrusions between BS 360 and BS 907 with new, improved support fittings, in accordance with Part 4 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, datedJanuary 16, 2008. \n\nCompliance Time for Certain Airplanes \n\n\t(h) For airplanes on which Boeing Business Jet (BBJ) lower cabin altitude modification is incorporated in accordance with Supplemental Type Certificate ST01697SE: Before the accumulation of 18,000 total flight cycles, or within 72 months after the effective date of this AD, whichever occurs later, do the actions specified in paragraphs (f) and (g) of this AD. \n\nActions Accomplished According to Previous Issue of Service Bulletin \n\n\t(i) Actions accomplished before the effective date of this AD according to Boeing Special Attention Service Bulletin 737-25-1544, dated October 4, 2006, are considered acceptable for compliance with the corresponding actions specified in this AD. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(j)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM- 120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6447; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. \n\t(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. \n\t(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. \n\nMaterialIncorporated by Reference \n\n\t(k) You must use Boeing Special Attention Service Bulletin 737- 25-1544, Revision 1, dated January 16, 2008, to perform the actions that are required by this AD, unless the AD specifies otherwise. \n\t(1) The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. \n\t(2) Contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1, fax 206-766-5680; e-mail me.boecom@boeing.com; Internet https://www.myboeingfleet.com, for a copy of this service information. \n\t(3) You may review copies of the service information that is incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152. \n\t(4) You may also review copies of the service information at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_ regulations/ibr_locations.html.

Discussion \n\n\tThe FAA issued a supplemental notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes. That supplemental NPRM was published in the Federal Register on August 19, 2008 (73 FR 48307). That supplemental NPRM proposed to require a one- time general visual inspection of frames between body station (BS) 360 and BS 907 to determine if certain support brackets of the air conditioning (A/C) outlet extrusions are installed; medium- and high- frequency eddy current inspections for cracking of the frames around the attachment holes of the subject brackets; and repair if necessary. That supplemental NPRM also proposed to require installing new, improved fittings for all support brackets of the A/C outlet extrusions between BS 360 and BS 907. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of thisAD. We have considered the comments received. \n\nRequest To Revise "Estimated Costs'' Table \n\n\tBoeing requests that we revise the "Estimated Costs'' table in the Cost of Compliance paragraph of the supplemental NPRM to match the information specified in Boeing Special Attention Service Bulletin 737- 25-1544, Revision 1, dated January 16, 2008. Boeing states that the parts cost in the supplemental NPRM reflects a price range between $56,095 and $81,339, while the price range specified in the Boeing special attention service bulletin is between $19,854 and $28,789. We referred to the Boeing special attention service bulletin as the appropriate source of service information for doing the actions specified in the supplemental NPRM. \n\tWe agree with the commenter's request to revise the parts cost to match the information specified in Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. We have revised the parts cost to specify "between $19,854 and$28,789'' and we have revised the corresponding "Cost per Airplane'' and "Fleet Cost'' columns in the "Estimated Costs'' table of this AD. \n\nRequest To Clarify the References to the Boeing Special Attention Service Bulletin \n\n\tBoeing requests that we clarify the references to Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008, in paragraphs (g), (g)(2), and (h) of the supplemental NPRM. Boeing states that the supplemental NPRM reads "* * * in accordance with Part 2 of the service bulletin * * *'' when the reference is meant to be "* * * in accordance with Part 2 of the accomplishment instructions of the service bulletin. \n\n* * *'' Boeing further states the service bulletin is divided into\nthree parts with Part 3 being the accomplishment instructions. Boeing notes that the accomplishment instructions are further divided into four parts, which are referenced in the supplemental NPRM. \n\tWe agree to clarify the references to Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008. However, we had already included the phrase "Accomplishment Instructions'' in paragraph (f) of the supplemental NPRM as part of the definition of "service bulletin.'' Paragraph (f) of the supplemental NPRM states that "the term 'service bulletin,' as used in this AD, means the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-25-1544, Revision 1, dated January 16, 2008.'' \n\tTo avoid any confusion as to which part of the service bulletin we are referring to in the AD, we have removed paragraph (f) of the supplemental NPRM from this AD and revised the subsequent paragraph identifiers accordingly. We have also included the phrase "Accomplishment Instructions'' in the references to the service bulletin in paragraphs (f), (f)(2), and (g) of this AD. \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 1,679 airplanes of the affected design in the worldwide fleet. This AD affects about 626 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this AD, at an average labor rate of $80 per work hour. Operators should note that special cold working tools and sleeves will be needed if any repair is required, which may increase costs. \n\n\tEstimated Costs\n\n\nAction\nWork Hours\nParts\nCost per Airplane\nFleet Cost\nGeneral visual inspection\n1\nNo parts required\n$80\n$50,080\nMFEC and HFEC inspections\nBetween 170 and 216\nNo parts required\nBetween $13,600 and $17,280\nUp to $10,817,280\nReplace support fittings\nBetween 258 and 346\nBetween $19,854 and $28,789\nBetween $40,494 and $56,469\nUp to $35,349,594\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\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\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\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):