AD 2001-09-15

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 737-200 and -300 series airplanes, that currently requires repetitive inspections to detect cracking in the radii on the support angles on the lower jamb (latch lug fittings) of the main deck cargo door, and replacement of cracked parts. This amendment adds a requirement for installation of redesigned lower jamb latch support angles in the main cargo door surround structure, which would terminate the repetitive inspections. This amendment is prompted by the development of a modification that will provide better protection of the subject area against effects of structural fatigue. The actions specified by this AD are intended to prevent in-flight separation of the main deck cargo door from the airplane due to fatigue cracking on the support angles on the lower door jamb.

Final rule.

2001-09-15 Boeing: Amendment 39-12222. Docket 99-NM-85-AD. Supersedes AD 95-01-06 R1, Amendment 39-9449. \n\n\tApplicability: Model 737-200 and -300 series airplanes equipped with main deck cargo doors installed in accordance with supplemental type certificate (STC) SA2969SO, certificated in any category. \n\n\tNote 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent in-flight separation of the main deck cargo door from the airplane, accomplish the following: \n\n\tNote 2: This AD references Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 1994; Pemco Service Bulletin 737-53-0003, Revision 4, dated February 22, 1995; and Pemco Service Bulletin 737-53-0003, Revision 5, dated March 25, 1999; for information concerning inspection and replacement procedures. In addition, this AD specifies replacement requirements different from those included in the service letter or service bulletin. Where there are differences between the AD and the service letter or service bulletin, the AD prevails. \n\nRestatement of Requirements AD 95-01-06 R1 \n\nRepetitive Inspections \n\n\t(a) Within 50 flight cycles after January 24, 1995 (the effective date of AD 95-01-06, amendment 39-9117), or within 50 flight cycles after installation of STC SA2969SO, whichever occurs later, perform a detailed visual inspection to detect cracking in the radii on the support angles on the lower jamb of the main deck cargo door, in accordance with Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 1994. \n\n\t\t(1) If no cracking is detected, repeat the detailed visual inspection thereafter at intervals not to exceed 450 flight cycles. \n\n\t\t(2) If any cracking is detected, prior to further flight, replace the cracked part with a new part in accordance with the alert service letter. Repeat the detailed visual inspection thereafter at intervals not to exceed 450 flight cycles. \n\n\tNote 3: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemedappropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." \n\nNew Requirements of This AD \n\nTerminating Action \n\n\t(b) Within 1,500 flight cycles after the effective date of this AD, install redesigned lower jamb latch lug support angles in the main cargo door surround structure in accordance with Pemco Service Bulletin 737-53-0003, Revision 4, dated February 22, 1995, or Revision 5, dated March 25, 1999. This action constitutes terminating action for the requirements of this AD. \n\nAlternative Methods of Compliance \n\n\t(c)\t(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Atlanta Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO. \n\n\t\t(2) Alternative methods of compliance, approved previously in accordance with AD 95-01-06 R1, amendment 39-9449, are approved as alternative methods of compliance with paragraphs (a) and (b) of this AD. \n\n\tNote 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO. \n\nSpecial Flight Permits \n\n\t(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\nIncorporation by Reference \n\n\t(e) The actions shall be done in accordance with Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 1994; Pemco Service Bulletin 737-53-0003, Revision 4, dated February 22, 1995, or Pemco Service Bulletin 737-53-0003, Revision 5, dated March 25, 1999; as applicable. \n\n\t\t(1) The incorporation by reference of Pemco Service Bulletin 737-53-0003, Revision 4, dated February 22, 1995; and Pemco Service Bulletin 737-53-0003, Revision 5, dated March 25, 1999; is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. \n\n\t\t(2) The incorporation by reference of Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 1994, was approved previously by the Director of the Federal Register as of January 24, 1995 (60 FR 2323, January 9, 1995). \n\n\t\t(3) Copies may be obtained from Pemco Aeroplex, Inc., P.O. Box 2287, Birmingham, Alabama 35201-2287. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Atlanta ACO, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\nEffective Date \n\n\t(f) This amendment becomes effective onJune 14, 2001.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 95-01-06 R1, amendment 39-9449 (60 FR 62192, December 5, 1995), which is applicable to certain Boeing Model 737-200 and -300 series airplanes, was published in the Federal Register on November 22, 1999 (64 FR 63757). The action proposed to continue to require repetitive inspections to detect cracking in the radii on the support angles on the lower jamb (latch lug fittings) of the main deck cargo door, and replacement of cracked parts. That action also adds a requirement for installation of redesigned lower jamb latch support angles in the main cargo door surround structure, which would terminate the repetitive inspections. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. Two commenters state that the airplanes they operate would not beaffected by the proposed rule. \n\nInclude Additional Service Information \n\n\tOne commenter asks that Pemco Service Bulletin 737-53-0005, dated November 18, 1997, which specifies alignment of the door latch base and frames, be included as an alternative method of compliance in paragraph (c)(1) of the proposed rule. The commenter also asks that the actions specified in that service bulletin be added to the proposed rule as terminating action for the requirements of AD 95-01-06 R1 (above). The commenter states that its fleet was modified per the service bulletin referenced in the proposed rule, but one airplane was misaligned between the door latch base and fuselage framing at FS 490.8. The commenter accomplished the alignment specified in service bulletin 737-53-0005. \n\n\tThe FAA does not concur with the commenter's requests. The FAA does not find it necessary to revise this AD to include special instructions for airplanes modified with another service bulletin. Operators should notethat most AD actions address modifications affecting the subject area of the AD using the note that appears as Note 1 of this AD, which states, "For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance (AMOC) in accordance with paragraph (c)(1) of this AD." The AMOC letter would be issued to the operator by the appropriate office, as stated in paragraph (c)(1). \n\n\tAdditionally, the service bulletin referenced in the final rule specifies installation of redesigned lower jamb latch support angles in the main cargo door surround structure, which would terminate the repetitive inspections. Modification of the door latch base for better alignment is a separate issue that was not addressed in the proposed rule, and would not meet the requirements for the terminating action. No change to the final rule is necessary in this regard. \n\nConclusion \n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. \n\nCost Impact \n\n\tThere are approximately 32 airplanes of the affected design in the worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry will be affected by this AD. \n\n\tThe inspection that is currently required by AD 95-01-06 R1, and retained in this AD, takes approximately 8 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $480 per airplane, per inspection cycle. \n\n\tThe new installation that is required by this AD takes approximately 500 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $9,700 per airplane. Based on these figures, the cost impact of the requirements of this AD on U.S. operators is estimated to be $79,400, or $39,700 per airplane. \n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein 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. Therefore, it is determined that thisfinal rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \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\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. 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\n\t2. Section 39.13 is amended by removing amendment 39-9449 (60 FR 62192, December 5, 1995), and by adding a new airworthiness directive (AD), amendment 39-12222, to read as follows: