AD 2008-21-03

We are adopting a new airworthiness directive (AD) for all Boeing Model 737-300, -400, and -500 series airplanes. This AD 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 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. We are issuing this AD to detect and correct discrepancies 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.

2008-21-03 Boeing: Amendment 39-15687. Docket No. FAA-2008-0357; Directorate Identifier 2008-NM-005-AD. \n\nEffective Date \n\n\t(a) This airworthiness directive (AD) is effective November 13, 2008. \n\nAffected ADs \n\n\t(b) None. \n\nApplicability \n\n\t(c) This AD applies to all Boeing Model 737-300, -400, and -500 series airplanes, certificated in any category. \n\nUnsafe Condition \n\n\t(d) 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. We are issuing this AD to detect and correct 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. \n\nCompliance \n\n\t(e) Comply with this AD within the compliance times specified, unless already done. \n\nRepetitive Inspections/Corrective Actions \n\n\t(f) 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 the service bulletin specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD: 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 the service bulletin. Do all applicable corrective actions before further flight. Repeat the inspection at the time specified in paragraph 1.E. of the service bulletin. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(g)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Allen Rauschendorfer, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6432; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested using 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. \n\nMaterial Incorporated by Reference \n\n\t(h) You must use Boeing Special Attention Service Bulletin 737- 54-1044, dated December 10, 2007, to do the actions 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 service information under 5 U.S.C. 552(a) and 1 CFR part 51. \n\t(2) For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. \n\t(3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 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\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR Part 39 to include an airworthiness directive (AD) that would apply to all Boeing Model 737-300, -400, and -500 series airplanes. That NPRM was published in the Federal Register on March 26, 2008 (73 FR 15959). That NPRM proposed 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. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the comments received. \n\nSupport for the NPRM \n\n\tBoeing supports the NPRM. \n\tDeutsche Lufthansa (DLH) states that during inspections done per the AMM, for which the left- and right-hand pylons have to be removed, it observed several instances of corrosion or damaged chrome plating of the midspar fuse pins; the defective pins were replaced. Therefore, DLH supports the repetitive inspections of the fuse pins. \n\nRequest for Credit for Initial Inspection \n\n\tDLH asks that the initial inspection procedure done per Maintenance Planning Document (MPD) Item 54-322-01, of the applicable airplane maintenance manual (AMM), be acceptable for compliance with the initial inspection required by the NPRM. In addition, DLH does not support the compliance times for the initial inspection. DLH feels that the inspection of the fuse pins done during its maintenance check per the AMM provides the same level of safety as the initial inspection done per the service bulletin referenced in the NPRM. \n\tWe do not agree. The AMM only includes procedures for access and does not provide inspection procedures; therefore, the service bulletin provides the inspection procedures. If DLH believes that its inspection procedures provide an acceptable alternative, under the provisions of paragraph (g) of this AD, we will consider requests for approval of an alternative method of compliance if sufficient data are submitted to substantiate that the alternative inspection would provide an acceptable level of safety. \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 that this AD will affect 616 airplanes of U.S. registry. We also estimate that it will take 4 work-hours per product to comply with the inspection in this AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $197,120, or $320 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\tWe are issuing thisrulemaking 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\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\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\tYou can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. \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 AD: