Airworthiness Directive · Amendment 39-18010 · 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; 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; Model DC-9-41 airplanes; and Model DC-9-51 airplanes; certificated in any category; equipped with a ventral aft pressure bulkhead.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model DC-9-10, DC-9-20, DC-9-30, DC-9-40, and DC-9- 50 series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the bulkhead dome tees, which connect the bulkhead web to the fuselage, are subject to widespread fatigue damage (WFD). This AD requires repetitive inspections of the improved ventral aft pressure bulkhead tees, and replacement if necessary. We are issuing this AD to detect and correct fatigue cracking of the bulkhead dome tees, 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) 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) ventral aft pressure bulkhead web to fuselage skin attach tee sections.
For airplanes on which an improved tee section having P/N 5910130-389, 5910130-391, 5910130-392, 5910130-393, 5910130-394, 5910130-387, SR09530001-19, SR09530001-21, SR09530001-22, SR09530001-23, SR09530001-24, SR09530001-25, SR09530001-29, SR09530001-30, SR09530001-31, SR09530001-32, SR09530001-33, SR09530001-35, SR09530056-3, SR09530056-5, SR09530056-6, SR09530056-7, SR09530056-8, SR09530056-9, SR09530056-19, 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 general visual and low frequency eddy current inspections (Option I), or high and low frequency eddy current inspections (Option II), for cracking of the improved tee sections, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.
(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 70,000 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 listed in paragraph (h) of this AD, is not known, do the initial inspection required by paragraph (h) of this AD before the accumulation of 105,000 total flight cycles on the airplane 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 Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.
(1) For Option I: If Option I was used for the inspection required by paragraph (h) of this AD, repeat the inspections specified in paragraphs (j)(1)(i), (j)(1)(ii), and (j)(1)(iii) of this AD at the intervals specified in paragraphs (j)(1)(i), (j)(1)(ii), and (j)(1)(iii) of this AD.
(i) Repeat the low frequency eddy current inspection for cracking of side areas above the floor between longerons L7 and L17 on the fuselage, at intervals not to exceed 1,500 flight cycles.
(ii) Repeat the general visual inspection for cracking of the top and lower areas from longeron L7 left side to longeron L7 right side, and lower fuselage longeron L17 to longeron L20 on the 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 longeron 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 frequency eddy current inspection for cracking around the entire periphery of the fuselage on 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 listed in paragraph (h) of this AD, or with an original tee section having P/N 5910130-47, 5910130-51, 5910130-53, 5910130-54, 5910130-55, or 5910130-56, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.
(1) If the tee section is replaced with an improved tee section listed in paragraph (h) of this AD, prior to the accumulation of 70,000 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 35,000 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.
