AD 2009-04-16

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747-100, 747-100B, 747- 200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. That AD currently requires an inspection to determine if acceptable external skin doublers are installed at the stringer 6 (S-6) lap splices, between station (STA) 340 and STA 400. For airplanes without the acceptable external skin doublers, the existing AD also requires repetitive related investigative actions and corrective actions if necessary. The existing AD also provides an optional terminating modification for the repetitive related investigative actions. This new AD mandates the optional terminating modification. This AD results from a report of cracked fastener holes at the right S-6 lap splice between STA 340 and STA 380. We are issuing this AD to prevent cracking in the fuselage skin, which could result in rapid decompression and loss of structural integrity of the airplane.

Final rule.

2009-04-16 Boeing: Amendment 39-15822. Docket No. FAA-2008-1006; Directorate Identifier 2008-NM-110-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective April 2, 2009. \n\nAffected ADs \n\n\t(b) This AD supersedes AD 2008-10-15. \n\nApplicability \n\n\t(c) This AD applies to Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008. \n\nUnsafe Condition \n\n\t(d) This AD results from a report of cracked fastener holes at the right stringer 6 (S-6) lap splice between station (STA) 340 and STA 380. We are issuing this AD to prevent cracking in the fuselage skin, which could result in rapid decompression and loss of structural integrity 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.Requirements of AD 2008-10-15 \n\nService Bulletin Reference Paragraph \n\n\t(f) The term "alert service bulletin,'' as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008. \n\nInspection for Acceptable External Skin Doublers \n\n\t(g) For airplanes identified as Group 1, Configuration 2, in Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008: At the latest of the times specified in paragraphs (g)(1), (g)(2), and (g)(3) of this AD, do an external general visual inspection to determine if acceptable external skin doublers are installed at the left- and right-side S-6 lap splices, in accordance with Part 1 of the alert service bulletin. \n\t(1) Prior to the accumulation of 10,000 total flight cycles. \n\t(2) Within 8,000 flight cycles after a modification was done in accordance with Boeing Service Bulletin 747-53-2253. \n\t(3) Within 15 days or 100 flight cycles after May 20, 2008 (the effective date of AD 2008-10-15), whichever occurs first. \n\nAcceptable External Skin Doublers Found at Both Sides \n\n\t(h) If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers in accordance with the alert service bulletin are found installed at both the left- and right- side S-6 lap splices, no further work is required by this AD. \n\nAcceptable External Skin Doublers Not Found--Repetitive Related Investigative Actions and Corrective Actions \n\n\t(i) If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers in accordance with alert service bulletin are not found installed at either the left- or right-side S-6 lap splice: Before further flight, do all applicable related investigative and corrective actions by doing all actions specified in Part 2 of the alert service bulletin. Repeat the applicable related investigative actions thereafter at intervals not to exceed 300 flight cycles until the modification specified in paragraph (j) of this AD is done. \n\nNew Requirement of This AD \n\nTerminating Modification \n\n\t(j) If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers as specified in the alert service bulletin are not found installed at either the left- or right-side S-6 lap splice: Within 3,000 flight cycles after doing the initial related investigative actions in paragraph (i) of this AD, or within 300 flight cycles after the effective date of this AD, whichever occurs later, install acceptable external skin doublers at both the left- and right-side S-6 lap splices, as applicable. The installation of the acceptable skin doublers is required on the side of the airplane that does not have the acceptable doublers already. The installation includes doing an open-hole high-frequency eddy current (HFEC) inspection of the skin for cracking, and trimming out cracking as applicable. Do all actions in accordance with the alert service bulletin. Doing this installation terminates the repetitive related investigative actions required by paragraph (i) of this AD. \n\n\tNote 1: The alert service bulletin refers to Boeing Service Bulletins 747-53-2253, Revision 3, dated March 24, 1994; and 747-53- 2272, Revision 18, dated May 16, 2002; as additional sources of service information for accomplishment of the modification (installation of acceptable external skin doublers). \n\n\tNote 2: AD 90-06-06, amendment 39-6490, requires, among other actions, a modification as specified in Boeing Service Bulletin 747- 53-2253, dated December 14, 1984. \n\n\tNote 3: AD 90-23-14, amendment 39-6801, requires inspections as specified in Boeing Service Bulletin 747-53-2253, Revision 2, dated March 29, 1990. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(k)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057- 3356; telephone (425) 917-6437; 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 and the approval must specifically refer to this AD. \n\nMaterial Incorporated by Reference \n\n\t(l) You must useBoeing Alert Service Bulletin 747-53A2748, dated May 9, 2008, to do the actions required by this AD, unless the AD specifies otherwise. \n\t(1) The Director of the Federal Register previously approved the incorporation by reference of Boeing Alert Service Bulletin 747- 53A2748, dated May 9, 2008, on May 20, 2008 (73 FR 29042, May 20, 2008). \n\t(2) For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207; telephone 206-544-9990; fax 206-766-5682; e-mail DDCS@boeing.com; Internet https://www.myboeingfleet.com. \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 informationon 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 notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that supersedes AD 2008-10-15, amendment 39-15522 (73 FR 29042, May 20, 2008). The existing AD applies to certain Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. That NPRM was published in the Federal Register on September 23, 2008 (73 FR 54755). That NPRM proposed to continue to require an inspection to determine if acceptable external skin doublers are installed at the stringer 6 (S-6) lap splices, between station (STA) 340 and STA 400. For airplanes without the acceptable external skin doublers, that NPRM also proposed to continue to require repetitive related investigative actions and corrective actions if necessary. That NPRM also proposed to require a previously optional terminating modification for the repetitive related investigative actions. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the single comment that has been received on the NPRM. The commenter, Boeing, concurs with the NPRM. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comment that has been received, and determined that air safety and the public interest require adopting the AD as proposed. \n\nCosts of Compliance \n\n\tThe inspection for acceptable external skin doublers that is required by AD 2008-10-15 and retained in this AD takes about 2 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the inspection for U.S. operators is $27,840, or $160 per airplane. \n\tThe cost for the terminating action depends on the results of the inspections. Therefore, we cannot calculate those costs because we do not know what doubler conditions operators will find. \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 relationshipbetween 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, theFAA 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 removing amendment 39-15522 (73 FR 29042, May 20, 2008) and by adding the following new airworthiness directive (AD):