Airworthiness Directive · Amendment 39-15393 · Boeing Model 737-300, -400, and -500 Series Airplanes
Boeing Model 737-300, -400, and -500 Series Airplanes
This AD applies to Boeing Model 737-300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 737-57-1210, Revision 2, dated June 13, 2007.
We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-300, -400, and -500 series airplanes. This AD requires repetitive inspections for cracking of the body buttock line (BBL) 0.07 floor beam between body station (BS) 651 and BS 676 and between BS 698 and BS 717, and related investigative and corrective actions if necessary. This AD also provides an optional terminating action for the repetitive inspections. This AD results from reports of cracking in the BBL 0.07 floor beam. We are issuing this AD to prevent failure of the main deck floor beams at certain body stations due to fatigue cracking, which could result in rapid decompression of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Before the accumulation of 20,000 total flight hours, or within 7,000 flight cycles after the effective date of this AD, whichever occurs later: Do the detailed inspections for cracking of the BBL 0.07 floor beam between body station (BS) 651 and BS 676 and between BS 698 and BS 717, and do all the applicable related investigative and corrective actions before further flight, by accomplishing all of the applicable actions specified in paragraphs B.2. and B.4. of the Accomplishment Instructions of Boeing Service Bulletin 737-57-1210, excluding Appendix A, Revision 2, dated June 13, 2007, except as provided by paragraph (g) of this AD. Repeat the inspections thereafter at intervals not to exceed 7,000 flight cycles. Installing a repair in accordance with paragraphs B.2. and B.4. of the Accomplishment Instructions of the service bulletin, or doing the modification in accordance with paragraph (h) of this AD, terminates the repetitive inspections for the applicable area only.
If any cracking is found during any inspection required by this AD, and Boeing Service Bulletin 737-57-1210, excluding Appendix A, Revision 2, dated June 13, 2007, specifies to contact Boeing for appropriate action: Before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (i) of this AD.
If no cracking is found during the detailed inspection and related investigative action required by paragraph (f) of this AD: Accomplishing the modification of the BBL 0.07 floor beam between BS 651 and BS 676 and between BS 698 and BS 717, as applicable, in accordance with paragraphs B.2. and B.4., as applicable, of the Accomplishment Instructions of Boeing Service Bulletin 737-57-1210, excluding Appendix A, Revision 2, dated June 13, 2007, terminates the repetitive inspections for the applicable area only.
