AD 2008-14-14

We are adopting a new airworthiness directive (AD) for certain Boeing Model 747-400 and 747-400D series airplanes. This AD requires a general visual inspection of the power feeder wire bundle of the auxiliary power unit (APU) where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube. This AD also requires related investigative and corrective actions if necessary. This AD results from a report that the power feeder wire bundle of the APU was found touching the hydraulic system return tube during inspection of an airplane. We are issuing this AD to prevent insufficient clearance between the wire bundle and hydraulic tube that could lead to chafing of the wire bundle, which could cause arcing and a consequent hydraulic fluid fire in an area outside of the smoke detection and fire extinguishing zone; this condition could result in an uncontrolled fire on the airplane.

Final rule.

2008-14-14 Boeing: Amendment 39-15609. Docket No. FAA-2007-0267; Directorate Identifier 2007-NM-245-AD. \n\nEffective Date \n\n\t(a) This airworthiness directive (AD) is effective August 21, 2008. \n\nAffected ADs \n\n\t(b) None. \n\nApplicability \n\n\t(c) This AD applies to Boeing Model 747-400 and 747-400D series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007. \n\nUnsafe Condition \n\n\t(d) This AD results from a report that the power feeder wire bundle of the auxiliary power unit (APU) was found touching the hydraulic system return tube during inspection of an airplane. We are issuing this AD to prevent insufficient clearance between the wire bundle and hydraulic tube that could lead to chafing of the wire bundle, which could cause arcing and a consequent hydraulic fluid fire in an area outside of the smoke detection and fire extinguishing zone; this condition could result in an uncontrolled fire on 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\nInspection and Related Investigative and Corrective Actions \n\n\t(f) Within 24 months after the effective date of this AD, do a general visual inspection of the power feeder wire bundle of the APU where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube, and do all the related investigative and corrective actions as applicable, by accomplishing all of the actions specified in the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007. The related investigative and corrective actions must be accomplished before further flight after the inspection. \n\nCredit for Actions Done According to Previous Issue of Service Bulletin(g) Actions done before the effective date of this AD in accordance with Boeing Special Attention Service Bulletin 747-24- 2257, dated May 18, 2006, are acceptable for compliance with the corresponding requirements of paragraph (f) of this AD. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(h)(1) The Manager, Seattle Aircraft Certification Office, FAA, 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\nMaterial Incorporated by Reference \n\n\t(i) You must use Boeing Special Attention Service Bulletin 747- 24-2257, Revision 1, dated August 2, 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 certain Boeing Model 747-400 and 747-400D series airplanes. That NPRM was published in the Federal Register on December 4, 2007 (72 FR 68106). That NPRM proposed to require a general visual inspection of the power feeder wire bundle of the auxiliary power unit (APU) where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube. That NPRM also proposed to require related investigative and corrective actions if necessary. \n\nComments \n\n\tWe gave the public the opportunity to participate in developing this AD. We considered the three comments received. \n\nSupportive Comment \n\n\tThe commenters Adam W. Rocks and Boeing support the NPRM. \n\nRequest To Revise Applicability \n\n\tBrady J. Mitchell, an employee of Boeing,requests that all Boeing Model 747-400 series airplanes converted from a passenger-to-freighter configuration be excluded from the applicability of the NPRM. Mr. Mitchell states that those airplanes will have new hydraulic tubes and eliminate the possibility of an insufficient clearance or potential chafing condition between the tubes and the power feeder wire bundles of the APU between stations 2040 and 2060. Mr. Mitchell concludes that such a configuration change fulfills the requirements in paragraph (f) of the NPRM. \n\tWe do not agree. We have reviewed the details of the passenger-to- freighter conversion to which the commenter refers. We have determined that there is not a common configuration for each airplane that is converted. Rather, the details of each conversion are likely to be different from airplane to airplane. Therefore, each conversion configuration needs to be evaluated to ensure the unsafe condition identified in this AD is corrected. For this reason, providing a blanket exception for all airplanes that are converted to a freighter configuration is not appropriate. However, anyone may apply for an alternative method of compliance (AMOC) for relief from the requirements of this AD. Under the provisions of paragraph (h) of this AD, we may consider requests for approval of an AMOC if sufficient data are submitted to substantiate that a passenger-to-freighter configuration change 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\tThere are about 462 airplanes of the affected design in the worldwide fleet. This AD affects 61 airplanes of U.S. registry. The required inspection takes 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the AD for U.S. operators is $4,880, or $80 per airplane.Authority 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\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:PART 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: