AD 2006-16-11

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-700 and 737-800 series airplanes. This AD requires performing a one-time high frequency eddy current inspection for cracking of the backup intercostals located above the cutout for the forward airstair door; doing related investigative and corrective actions if any crack is found; and doing other specified corrective actions if no crack is found. This AD results from a report of fatigue cracks discovered during a full-scale fatigue test conducted by the manufacturer. We are issuing this AD to detect and correct such cracking, which could result in more extensive fatigue cracking and lead to possible loss of cabin pressure.

Final rule.

2006-16-11 Boeing: Amendment 39-14711. Docket No. FAA-2006-24698; Directorate Identifier 2006-NM-026-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective September 13, 2006. \n\nAffected ADs \n\n\t(b) None. \n\nApplicability \n\n\t(c) This AD applies to Boeing Model 737-700 and 737-800 series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-53-1236, Revision 1, dated November 10, 2005. \n\nUnsafe Condition \n\n\t(d) This AD results from a report of fatigue cracks discovered during a full-scale fatigue test conducted by the manufacturer. We are issuing this AD to detect and correct such cracking, which could result in more extensive fatigue cracking and lead to possible loss of cabin pressure. \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 of Backup Intercostals \n\n\t(f) Before the accumulation of 24,000 total flight cycles, or within 4,500 flight cycles after the effective date of this AD, whichever comes later: Perform a high frequency eddy current (HFEC) inspection for cracking of the backup intercostals located above the cutout for the forward airstair door, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1236, Revision 1, dated November 10, 2005; and, before further flight, do related investigative actions and applicable corrective actions if any crack is found, and other specified corrective actions if no crack is found. Related investigative actions, applicable corrective actions, and other specified corrective actions must be done in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-53-1236, Revision 1, dated November 10, 2005; except where the service bulletin specifies to contact Boeing for repair instructions, repair all cracks using a method approved in accordance with the procedures specified in paragraph (h) of this AD. \n\nActions Accomplished Using Original Issue of Service Bulletin \n\n\t(g) Actions accomplished before the effective date of this AD in accordance with Boeing Service Bulletin 737-53-1236, dated July 11, 2002, are considered acceptable for compliance with the corresponding requirements 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 in accordance with the procedures found in 14 CFR 39.19. \n\t(2) Before using any AMOC approved in accordance with Sec. 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. \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(i) You must use Boeing Special Attention Service Bulletin 737- 53-1236, Revision 1, dated November 10, 2005, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html .

Examining the Docket \n\n\tYou may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section. \n\nDiscussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Boeing Model 737-700 and 737-800 series airplanes. That NPRM was published in the Federal Register on May 9, 2006 (71 FR 26873). That NPRM proposed to require performing a one-time high frequency eddy current (HFEC) inspection for cracking of the backup intercostals located above the cutout for the forward airstair door; doing related investigative and corrective actions if any crack is found; and doing other specified corrective actions if no crack is found. \n\nComment \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the single comment received. The commenter, Boeing, supports the NPRM. \n\nClarification to NPRM \n\n\tThe first reference to Boeing Special Attention Service Bulletin 737-53-1236, Revision 1, dated November 10, 2005, in paragraph (f) of the NPRM was unintentionally omitted, and has been added to that paragraph of this AD. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comment received, and determined that air safety and the public interest require adopting the AD with the change described previously. We have determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCosts of Compliance \n\n\tThere are about 146 airplanes of the affected design in the worldwide fleet. This AD will affect about 54 airplanes of U.S. registry. The required HFEC inspection will take 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 AD for U.S. operators is $8,640, or $160 per airplane. \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 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\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. Seethe 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, 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 Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):