AD 2010-24-01

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires doing a one-time general visual inspection for a keyway in two fuel tank access door cutouts, and related investigative and corrective actions if necessary. This AD was prompted by reports of cracks emanating from the keyway of the fuel tank access hole. We are issuing this AD to detect and correct such cracking, which could result in the loss of the lower wing skin load path and consequent structural failure of the wing.

Final rule.

2010-24-01 The Boeing Company: Amendment 39-16519; Docket No. FAA- 2010-0764; Directorate Identifier 2009-NM-260-AD. \n\nEffective Date \n\n\t(a) This AD is effective December 29, 2010. \n\nAffected ADs \n\n\t(b) None. \n\nApplicability \n\n\t(c) This AD applies to The Boeing Company Model 737-900ER series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-57A1308, Revision 1, dated October 1, 2009. \n\nSubject \n\n\t(d) Air Transport Association (ATA) of America Code 57: Wings. \n\nUnsafe Condition \n\n\t(e) This AD results from reports of cracks emanating from the keyway of the fuel tank access hole. The Federal Aviation Administration is issuing this AD to detect and correct such cracking, which could result in the loss of the lower wing skin load path and consequent structural failure of the wing. \n\nCompliance \n\n\t(f) 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\nInspection \n\n\t(g) Before the accumulation of 7,500 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, do a one-time general visual inspection for a keyway in the fuel tank access door cutouts 531BB and 631BB, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1308, Revision 1, dated October 1, 2009 ("the service bulletin''). \n\n\tNote 1: For the purposes of this AD, a general visual inspection is: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.'' \n\n\t(1) If both access door cutouts do not have a keyway, no further action is required by this AD. \n\n\t(2) If any access door has a keyway, before the accumulation of 7,500 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, do a high frequency eddy current (HFEC) inspection for cracking of the keyway, in accordance with the Accomplishment Instructions of the service bulletin. \n\n\t(i) If no cracking is found during the HFEC inspection, before further flight, modify the profile of the keyway of the fuel tank access door cutout, in accordance with the Accomplishment Instructions of the service bulletin. \n\n\t(ii) If any cracking is found and the crack is 0.030 inch or less in length, before further flight repair the keyway, in accordance with the Accomplishment Instructions of the service bulletin. \n\n\t(iii) If any cracking is found and the crack is greater than 0.030 inch in length, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (h) of this AD. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440; fax (425) 917-6590. Information may be e-mailed to: 9-ANM-Seattle-ACO-AMOC- Requests@faa.gov. \n\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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD. \n\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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that 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\nRelated Information \n\n\t(i) For more information about this AD, contact Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440; fax (425) 917-6590; e-mail nancy.marsh@faa.gov. \n\nMaterial Incorporated byReference \n\n\t(j) You must use the Boeing Alert Service Bulletin 737-57A1308, Revision 1, dated October 1, 2009, to do the actions required by this AD, unless the AD specifies otherwise. \n\n\t(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51. \n\n\t(2) For service information identified in this AD, 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. \n\n\t(3) You may review copies of the service information 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. \n\n\t(4) You may also review copies of the service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at an NARA facility, call 202-741-6030, or go to http:// www.archives.gov/federal_register/code_of_federal_regulations/ ibr_locations.html.

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 the specified products. That NPRM published in the Federal Register on August 10, 2010 (75 FR 48281). That NPRM proposed to require a general visual inspection for a keyway in the fuel tank access door cutout on the left and right wings, and related investigative and corrective actions if necessary. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We have considered the comments received. The Boeing Company supports the NPRM. Continental Airlines submitted information to make a comment, but no specific comment on the NPRM or request to change it. \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\tWe estimate thatthis AD affects 30 airplanes of U.S. registry. We estimate that it will take 3 work-hours per product to comply with this AD. The average labor rate is $85 per work-hour. Based on these figures, we estimate the cost of the AD to the U.S. operators to be $7,650, or $255 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 thescope 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), \n\n\t(3) Will not affect intrastate aviation in Alaska, and \n\n\t(4) 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\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 airworthiness directive (AD):