Airworthiness Directive · Amendment 39-18009 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, and DC-9-15F airplanes; Model DC-9-21 airplanes; and Model DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, and DC-9-32F (C-9A, C-9B) airplanes; certificated in any category; equipped with a non-ventral aft pressure bulkhead.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model DC-9-10, DC-9-20, and DC-9-30 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the improved (shot-peened) aft fuselage non-ventral pressure bulkhead tee is subject to widespread fatigue damage (WFD). This AD requires repetitive inspections for cracking of the improved (shot-peened) non-ventral aft pressure bulkhead tees, and replacement if necessary. We are issuing this AD to detect and correct fatigue cracking of the improved (shot-peened) non-ventral aft pressure bulkhead tees connecting the bulkhead web to the fuselage, which could result in reduced structural integrity and rapid decompression of the airplane.
(1) For the purposes of this AD, the term “original tee section” refers to the original (non-peened) non-ventral aft pressure bulkhead web to fuselage skin attach tee sections.
(2) For the purposes of this AD, the term “improved tee section” refers to improved (shot peened) non-ventral aft pressure bulkhead web to fuselage skin attach tee sections.
For airplanes on which an improved tee section having P/N 5910163-257, 5910163-259, 5910163-260, 5910163-261, 5910163-262, 5910163-263, SR09530001-3, SR09530001-5, SR09530001-6, SR09530001-7, SR09530001-8, SR09530001-9, SR09530001-29, SR09530001-30, SR09530001-31, SR09530001-32, SR09530001-33, SR09530001-35, SR09530056-3, SR09530056-5, SR09530056-6, SR09530056-7, SR09530056-8, SR09530056-9, SR09530056-11, SR09530056-13, SR09530056-14, SR09530056-15, SR09530056-16, SR09530056-17, SR09530056-19, SR09530056-21, SR09530056-22, SR09530056-23, SR09530056-24, or SR09530056-25, is installed: At the applicable time specified in paragraph (i)(1) or (i)(2) of this AD, do a general visual and low frequency eddy current (LFEC) inspection (Option I), or a high and low frequency eddy current inspection (Option II), for cracking of the improved tee sections, in accordance with the Accomplishment Instructions of McDonnell Douglas DC-9 Alert Service Bulletin A53-231, Revision 2, dated June 25, 1993, including Service Sketch 3683D, Revision C, dated July 19, 1989.
(1) For Option I and Option II inspections specified in paragraph (h) of this AD: If the time of installation of an improved tee section having a part number listed in paragraph (h) of this AD is known, do the initial inspection required by paragraph (h) of this AD within 50,000 flight cycles after installation of the improved tee section, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
(2) For Option I and Option II inspections specified in paragraph (h) of this AD: If the time of installation of an improved tee section having a part number identified in paragraph (h) of this AD is not known, do the initial inspection required by paragraph (h) of this AD before the accumulation of 75,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
If no cracking is found during the inspection required by paragraph (h) of this AD: Do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable, in accordance with the Accomplishment Instructions of McDonnell Douglas DC-9 Alert Service Bulletin A53-231, Revision 2, dated June 25, 1993, including Service Sketch 3683D, Revision C, dated July 19, 1989.
(1) For Option I: If Option I was used for the inspection required by paragraph (h) of this AD, do the actions at the applicable intervals, as specified in paragraphs (j)(1)(i), (j)(1)(ii), and (j)(1)(iii) of this AD.
(i) Repeat the LFEC inspection for cracking of the side areas above the floor between longerons L7 and L17 on the fuselage left and right sides, at intervals not to exceed 2,000 flight cycles.
(ii) Repeat the general visual inspection for cracking of the top and lower areas from longeron L7 left side to L7 right side, and lower fuselage longeron L17 to L20 on the fuselage left and right sides, at intervals not to exceed 1,500 flight cycles.
(iii) Repeat the general visual inspection for cracking of the bottom areas from longeron L20 left side to L20 right side, at intervals not to exceed 3,500 flight cycles.
(2) For Option II: If Option II was used for the inspection required by paragraph (h) of this AD, repeat the high and low eddy frequency eddy current inspections for cracking around the entire periphery of the fuselage from the forward side of the bulkhead at intervals not to exceed 2,500 flight cycles.
If any cracking is found during any inspection required by paragraph (h) or (j) of this AD: Before further pressurized flight, replace each cracked tee section with an airworthy tee section having a part number identified in paragraph (h) of this AD, or with an original tee section having P/N 5910163-89, 5910163-91, 5910163-92, 5910163-93, 5910163-94, or 5910163-95, in accordance with the Accomplishment Instructions of McDonnell Douglas DC-9 Alert Service Bulletin A53-231, Revision 2, dated June 25, 1993, including Service Sketch 3683D, Revision C, dated July 19, 1989.
(1) If the tee section is replaced with an improved tee section listed in paragraph (h) of this AD, prior to the accumulation of 50,000 flight cycles after installation, inspect the tee section in accordance with paragraph (h) of this AD and do all applicable corrective actions and repetitive inspections in accordance with and at the times specified in paragraphs (j) and (k) of this AD.
(2) If the tee section is replaced with an original tee section listed in paragraph (k) of this AD, prior to the accumulation of 25,000 flight cycles after installation, inspect the tee section in accordance with paragraph (h) of this AD and do all applicable corrective actions and repetitive inspections in accordance with and at the times specified in paragraphs (j) and (k) of this AD.
