AD 93-14-10

93-14-10 BOEING: Amendment 39-8634. Docket 92-NM-161-AD. Supersedes AD 87-06-08 R1, Amendment 39-5763.

Applicability: Model 737-200 and -300 series airplanes, line numbers 6 through 1204, inclusive; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

NOTE 1: Paragraph (a) of this AD restates the requirements of paragraph (a) of AD 87-06-08 R1, amendment 39-5763. As allowed by the phrase, "unless accomplished previously," if the requirements of paragraph (a) of AD 87-06-08 R1 have been accomplished previously, paragraph (a) of this AD does not require that they be repeated.

To prevent the development of undetected frame cracking, which could result in rapid loss of cabin pressure, accomplish the following:

(a) Prior to the accumulation of 20,000 landings, or within 1,000 landings after December 17, 1987 (the effective date of AD 87-06-08 R1, amendment 39-5763), whichever occurs later, unless previously accomplished within the last 3,000 landings prior to December 17, 1987, conduct a close visual inspection to detect cracks of the forward and aft body frames adjacent to the aft lower cargo door, in accordance with Boeing Service Bulletin 737-53-1096, dated July 24, 1986; or Revision 1, dated April 2, 1987; or Revision 2, dated July 30, 1987; or Revision 3, dated February 8, 1990; or Revision 4, dated February 14, 1991; or Revision 5, dated January 16, 1992. Thereafter, repeat the detailed visual inspections at intervals not to exceed 4,000 landings.

(b) If any crack is detected during any of the inspections required by this AD, prior to further flight, accomplish the requirements of paragraph (b)(1) or (b)(2) of this AD, as applicable:

(1) Modify or repair the crack in accordance with Boeing Service Bulletin 737-53-1096, Revision 1, dated April 2, 1987; or Revision 2, dated July 30, 1987; or Revision 3, dated February 8, 1990; or Revision 4, dated February 14, 1991; or Revision5, dated January 16, 1992. After modification or repair, accomplish the requirements of paragraph (d) of this AD.

NOTE 2: Compliance with the requirements of paragraph (b)(1) of this AD constitutes compliance for the modification and crack repair recommendations of Boeing Service Bulletin 737-53-1096, as mandated by AD 90-06-02, amendment 39-6489.

(2) If any crack is found that does not exceed the limits specified in the Boeing 737 Structural Repair Manual (SRM), the crack may be temporarily repaired in accordance with the SRM. After such repair is accomplished, repeat the close visual inspections required by paragraph (a) of this AD at intervals not to exceed 4,000 landings until modification or repair is accomplished in accordance with the service bulletins specified in paragraph (b)(1) of this AD. After such modification or repair, accomplish the requirements of paragraph (d) of this AD.

(c) If no crack is detected during any of the inspections required by thisAD, repeat the close visual inspections required by paragraph (a) of this AD at intervals not to exceed 4,000 landings until modified in accordance with Boeing Service Bulletin 737-53-1096, Revision 1, dated April 2, 1987; or Revision 2, dated July 30, 1987; or Revision 3, dated February 8, 1990; or Revision 4, dated February 14, 1991; or Revision 5, dated January 16, 1992. After modification, accomplish the requirements of paragraph (d) of this AD.

(d) For any area that is modified or repaired in accordance with Boeing Service Bulletin 737-53-1096, initial release, dated July 24, 1986; Revision 1, dated April 2, 1987; Revision 2, dated July 30, 1987; Revision 3, dated February 8, 1990; Revision 4, dated February 14, 1991; or Revision 5, dated January 16, 1992: Prior to the accumulation of 28,000 landings after the modification or repair has been accomplished, or within 1,000 landings after the effective date of this AD, whichever occurs later, and thereafter at intervals not toexceed 4,000 landings, conduct a detailed visual inspection to detect cracks of the forward and aft body frames adjacent to the aft lower cargo door, in accordance with the service bulletin.

(e) 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, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(f) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(g) The inspections, modification, and repairs shallbe done in accordance with Boeing Service Bulletin 737-53-1096, initial release, dated July 24, 1986; or Boeing Service Bulletin 737-53-1096, Revision 1, dated April 2, 1987; or Boeing Service Bulletin 737-53-1096, Revision 2, dated July 30, 1987; or Boeing Service Bulletin 737-53-1096, Revision 3, dated February 8, 1990; or Boeing Service Bulletin 737-53-1096, Revision 4, dated February 14, 1991; or Boeing Service Bulletin 737-53-1096, Revision 5, dated January 16, 1992, as applicable. Revision 2 of Boeing Service Bulletin 737-53-1096 contains the specified effective pages:

Date Page Number Shown on Page Shown on Page 1-2, 4-18, 23 2 July 30, 1987 3, 19-22, 24 1 April 2, 1987

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(h) This amendment becomes effective on September 16, 1993.