AD 2011-01-12

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. This new AD requires replacing the midspar fuse pins with new, improved fuse pins, which would terminate the repetitive inspections. This AD was prompted by a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. We are issuing this AD to prevent damage of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structural integrity of the fuse pins, and consequent loss of the strut and separation of the engine from the airplane.

Final rule.

2011-01-12 The Boeing Company: Amendment 39-16566; Docket No. FAA- 2010-0855; Directorate Identifier 2010-NM-066-AD. \n\nEffective Date \n\n\t(a) This airworthiness directive (AD) is effective February 9, 2011. \n\nAffected ADs \n\n\t(b) This AD supersedes AD 2008-21-03, Amendment 39-15687. \n\nApplicability \n\n\t(c) This AD applies to all The Boeing Company Model 737-300, - 400, and -500 series airplanes, certificated in any category. \n\nSubject \n\n\t(d) Air Transport Association (ATA) of America Code 54: Nacelles/Pylons. \n\nUnsafe Condition \n\n\t(e) This AD results from a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. The Federal Aviation Administration is issuing this AD to prevent damage of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structuralintegrity of the fuse pins, and consequent loss of the strut and separation of the engine from the airplane. \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\nRestatement of Requirements of AD 2008-21-03 \n\nRepetitive Inspections/Corrective Actions, With Revised Service Information \n\n\t(g) At the applicable time specified in paragraph 1.E., "Compliance'' of Boeing Special Attention Service Bulletin 737-54- 1044, dated December 10, 2007; except, where that service bulletin specifies a compliance time after the date on that service bulletin, this AD requires compliance within the specified compliance time after November 13, 2008 (the effective date of AD 2008-21-03): Do a detailed inspection for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut by doing all the actions, including all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007; or Boeing Alert Service Bulletin 737-54A1044, Revision 2, dated January 20, 2010. Do all applicable corrective actions before further flight. Repeat the inspection at the time specified in paragraph 1.E. of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007. Accomplishing the actions of paragraph (h) of this AD terminates the requirements of this paragraph. \n\nNew Requirements of This AD \n\nReplacement \n\n\t(h) Within 120 months after the effective date of this AD, replace all midspar fuse pins having part number (P/N) 311A1092-2 with a midspar fuse pin having P/N 311A1092-3, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-54A1044, Revision 2, dated January 20, 2010. Accomplishing the requirements of this paragraph terminates the requirements of paragraph (g) of this AD for thatfuse pin. \n\nActions Accomplished According to Previous Revision of Service Information \n\n\t(i) Actions done before the effective date of this AD in accordance with Boeing Special Attention Service Bulletin 737-54- 1044, Revision 1, dated November 26, 2008, are acceptable for compliance with the corresponding requirements of this AD. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(j)(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: Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6450; 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\n\t(4) AMOCs approved in accordance with the requirements of AD 2008-21-03 are acceptable for the corresponding requirements of this AD. \n\nRelated Information \n\n\t(k) For more information about this AD, contact Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6450; fax (425) 917-6590; e-mail: alan.pohl@faa.gov. \n\nMaterial Incorporated by Reference \n\n\t(l) You must use Boeing Special Attention Service Bulletin 737- 54-1044, dated December 10, 2007; or Boeing Alert Service Bulletin 737-54A1044, Revision 2, dated January 20, 2010; as applicable; 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 Boeing Alert Service Bulletin 737- 54A1044, Revision 2, dated January 20, 2010, under 5 U.S.C. 552(a) and 1 CFR part 51. \n\n\t(2) The Director of the Federal Register previously approved the incorporation by reference of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007, on November 13, 2008 (73 FR 59493, October 9, 2008). \n\n\t(3) 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(4) You may review copies of the service information at the FAA, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221. \n\n\t(5) 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 supersede airworthiness directive (AD) 2008-21-03, Amendment 39-15687 (73 FR 59493, October 9, 2008). That AD applies to the specified products. The NPRM published in the Federal Register on September 23, 2010 (75 FR 57882). That NPRM proposed to continue to require repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. That NPRM also proposed to require replacing the midspar fuse pins with new, improved fuse pins, which would terminate the requirement for repetitive detailed inspections. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We have considered the comment received. Boeing supports the NPRM. \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\tThere are about 1,961 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD. \n\n\tEstimated Costs\n\n\nAction\nWork hours\nAverage labor rate per hour\nParts\nCost per airplane\nNumber of U.S.-registered airplanes\nFleet cost\nRepetitive detailed inspections (required by AD 2008-21-03)\n4\n$85\nnone\n$340, per inspection cycle\n616\n$209,440, per inspection cycle\nMidspar fuse pin replacement (new action)\n1 per pin (up to 4 pins per airplane)\n$85\n$843 per pin\nUp to $3,712\n616\nUp to $2,286,592\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), \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 removing airworthiness directive (AD) 2008-21-03, Amendment 39-15687 (73 FR 59493, October 9, 2008), and adding the following new AD: