AD 2006-12-17

The FAA is superseding an existing airworthiness directive (AD) which applies to all Boeing Model 737-200C series airplanes. That AD currently requires a one-time external detailed inspection for cracking of the fuselage skin in the lower lobe cargo compartment; repetitive internal detailed inspections for cracking of the frames in the lower lobe cargo compartment; repair of cracked parts; and terminating action for the repetitive internal detailed inspections. This new AD restates the requirements of the existing AD and adds a requirement to perform repetitive detailed inspections of the body station (BS) 360 and BS 500 fuselage frames, after accomplishing the terminating action, and repair if necessary. This AD results from multiple reports that the existing AD is not fully effective in preventing cracks in the BS 360 and BS 500 fuselage frames. We are issuing this AD to detect and correct cracking of the fuselage frames from BS 360 to BS 500B, which could lead to loss of the cargo door during flight and consequent rapid decompression of the airplane.

Final rule.

2006-12-17 Boeing: Amendment 39-14643. Docket No. FAA-2006-24245; Directorate Identifier 2005-NM-166-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective July 18, 2006. \n\nAffected ADs \n\n\t(b) This AD supersedes AD 99-12-08. \n\nApplicability \n\n\t(c) This AD applies to all Boeing Model 737-200C series airplanes, certificated in any category. \n\nUnsafe Condition \n\n\t(d) This AD results from multiple reports that the modification required by AD 99-12-08 is not fully effective in preventing cracks in the body station (BS) 360 and BS 500 fuselage frames. We are issuing this AD to detect and correct cracking of the fuselage frames from BS 360 to BS 500B, which could lead to loss of the cargo door during flight and consequent rapid decompression 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. \n\nRestatement of Requirements of AD 99-12-08 \n\nOne-Time External Detailed Inspection \n\n\t(f) Prior to the accumulation of 29,000 total flight cycles or within 250 flight cycles after August 9, 1993 (the effective date AD 93-13-02, amendment 39-8615, which was superseded by AD 99-12-08), whichever occurs later, accomplish an external detailed inspection to detect cracks of the fuselage skin between stringers 19 left and 25 left and at BS 360 to BS 540, in accordance with Boeing Alert Service Bulletin 737-53A1160, dated October 24, 1991; or Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 1993. If any crack is found, prior to further flight, accomplish the requirements of paragraphs (f)(1) and (f)(2) of this AD. \n\n\t(1) Perform an internal detailed inspection to detect cracks of the frames between stringers 19 left and 25 left and at BS 360 to BS 500B, in accordance with either service bulletin. \n\n\t(2) Repair all cracks in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), Transport Airplane Directorate, FAA. \n\nInternal Detailed Inspections \n\n\t(g) Within 3,000 flight cycles after completing the requirements of paragraph (f) of this AD, unless accomplished within the last 6,000 flight cycles prior to August 9, 1993, perform an internal detailed inspection to detect cracks of the frames between stringers 19 left and 25 left and at body stations 360 to 500B, in accordance with Boeing Alert Service Bulletin 737-53A1160, dated October 24, 1991; or Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 1993. Thereafter, repeat the internal detailed inspection at intervals not to exceed 9,000 flight cycles. If any crack is found during any inspection required by this paragraph, before further flight, repair as specified in paragraph (g)(1) or (g)(2) of this AD, as applicable. \n\n\t(1) If any crack is found that does not exceed the limits specified in the Boeing 737 Structural Repair Manual (SRM), repair the crack in accordance with amethod approved by the Manager, Seattle ACO; or in accordance with the procedures specified in paragraph (k)(4) of this AD. The SRM is one approved source of information for accomplishing the requirements of this paragraph. Repeat the internal detailed inspection thereafter at intervals not to exceed 9,000 flight cycles. \n\n\t(2) If any crack is found that exceeds the limits specified in the SRM, repair the crack in accordance with a method approved by the Manager, Seattle ACO; or in accordance with the procedures specified in paragraph (k)(4) of this AD. Repeat the internal detailed visual inspection thereafter at intervals not to exceed 9,000 flight cycles. \n\nInstall Doublers \n\n\t(h) Prior to the accumulation of 75,000 total flight cycles, or within 3,000 flight cycles after July 16, 1999 (the effective date of AD 99-12-08), whichever occurs later, install doublers on the specified frames located between stringers 19 left and 25 left from BS 360 to BS 500B, in accordance with Boeing Service Bulletin 737- 53A1160, Revision 1, dated April 29, 1993. Installing these doublers on the specified fuselage frames ends the repetitive inspections required by paragraphs (f) and (g) of this AD. \n\nNew Requirements of This AD \n\nRepetitive Inspection of Certain Frames \n\n\t(i) Within 9,000 flight cycles after accomplishing the modification required by paragraph (h) of this AD, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later, perform an internal detailed inspection to detect cracking in the fuselage frame at BS 360 and the fuselage frame at BS 500, between stringers 19 left and 25 left, in accordance with Boeing Alert Service Bulletin 737-53A1160, dated October 24, 1991; or Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 1993. Thereafter, repeat the internal detailed inspection of the BS 360 and BS 500 frames at intervals not to exceed 9,000 flight cycles. \n\n\t(j) If any crack is found during any inspection required by paragraph (i) of this AD, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (k) of this AD. \n\n\tNote 1: For the purposes of this AD, a detailed inspection is: "An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required." \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(k)(1) The Manager, Seattle ACO, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. \n\n\t(2) Before using any AMOC approved in accordance with 14 CFR 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\n\t(3) AMOCs approved previously in accordance with AD 99-12-08, including AMOCs approved previously in accordance with AD 93-13-02, are approved as AMOCs for the corresponding provisions specified in paragraphs (f), (g), and (h) of this AD. \n\n\t(4) 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 use Boeing Alert Service Bulletin 737-53A1160, dated October 24, 1991; or Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 1993, as applicable, to perform the actions that are requiredby this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of these documents on August 9, 1993 (58 FR 36863, July 9, 1993). 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 supersedes AD 99-12-08, amendment 39- 11192 (64 FR 31488, June 11, 1999). The existing AD applies to all Boeing Model 737-200C series airplanes. That NPRM was published in the Federal Register on March 30, 2006 (71 FR 16063). That NPRM proposed to require a one-time external detailed inspection for cracking of the fuselage skin in the lower lobe cargo compartment; repetitive internal detailed inspections for cracking of theframes in the lower lobe cargo compartment; repair of cracked parts; and terminating action for the repetitive internal detailed inspections. That NPRM also proposed to add a requirement to perform repetitive detailed inspections of the body station (BS) 360 and BS 500 fuselage frames, after accomplishing the terminating action, and repair if necessary. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the one comment received. The commenter, Boeing, supports the NPRM. \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 as proposed. \n\nCosts of Compliance \n\n\tThere are about 90 airplanes of the affected design in the worldwide fleet. This AD will affect about 18 airplanes of U.S. registry. \n\n\tThe modification required by AD 99-12-08, and retained in this AD, takes approximately 160 workhours per airplane to accomplish, at an average labor rate of $80 per work hour. Required parts cost about $5,500 per airplane. Based on these figures, the estimated cost of the currently required modification for U.S. operators is $329,400, or $18,300 per airplane. \n\n\tThe new inspections will take about 3 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the new inspections specified in this AD for U.S. operators is $4,320, or $240 per airplane, per inspection cycle. \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); and \n\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\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, 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 removing amendment 39-11192 (64 FR 31488, June 11, 1999) and by adding thefollowing new airworthiness directive (AD):