Airworthiness Directive · Amendment 39-18435 · Fuselage
The Boeing Company Airplanes
(1) This AD applies to The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014.
(2) Installation of Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/be866b732f6cf31086257b9700692796/$FILE/ST01219SE.pdf) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST01219SE is installed, a ”change in product” alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, and -500 series airplanes. This AD was prompted by reports of cracking at certain fastener locations in the window corners of the window belt area. This AD requires repetitive high frequency eddy current (HFEC) inspections for fatigue cracking in certain fastener locations in the window corners of the window belt area, and related investigative and corrective actions if necessary. This AD also provides an optional preventive modification that terminates the inspections at the modified location. We are issuing this AD to detect and correct fatigue cracking around fastener locations that could cause multiple window corner skin cracks, which could result in rapid decompression and loss of structural integrity of the airplane.
At the applicable time specified in tables 1 and 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, except as required by paragraph (j)(1) of this AD: Do external surface high frequency eddy current (HFEC) inspections for cracking of the skin at the 12 fastener locations at the upper forward and lower aft corners of each window between station (STA) 360 and STA 540 and at the upper aft and lower forward corners of each window between STA 727 and STA 908, left-side and right-side of the fuselage, at and between stringers S-11 and S-13; and all applicable related investigative and corrective actions; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, except as required by paragraphs (j)(2), (j)(3), (j)(4), and (j)(5) of this AD. Do all applicable related investigative and corrective actions before further flight. Repeat the inspections at the applicable times specified in tables 1 and 2 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014. Accomplishing the preventive modification specified in paragraph (h) of this AD terminates the repetitive inspections required by this paragraph at the modified location only.
(1) The inspections required by the introductory text of paragraph (g) of this AD may be terminated in areas with repairs installed prior to the effective date of this AD, provided the repairs are reinforcing and address the cracking issue identified in this AD, and installation was approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) via FAA Form 8100-9.
(2) For Group 1 airplanes identified in Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014: Window corner crack repairs terminate the inspection required by the introductory text of paragraph (g) of this AD in the repaired area only. The repair, including all applicable related investigative and corrective actions, must be done in accordance with Part 6 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, except as required by paragraphs (j)(2), (j)(3), (j)(4), and (j)(5) of this AD.
Accomplishment of a preventive modification in the fastener locations in the window corners of the window belt area between STA 360 and STA 540 and between STA 727 and STA 908, left-side and right-side of the fuselage, at and between stringers S-11 and S-13, terminates the inspections required by paragraph (g) of this AD at the modified location only. The modification, including all applicable related investigative and corrective actions, must be done in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, except as required by paragraphs (j)(2), (j)(3), (j)(4), and (j)(5) of this AD.
For airplanes having any condition identified in Table 4 or Table 5 of paragraph l.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014: At the applicable times specified in Table 4 and Table 5 of paragraph l.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, do a window frame replacement or an internal detailed inspection for cracks of the window forging around the fastener collars, as applicable, and do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, except as required by paragraphs (j)(2), (j)(3), (j)(4), and (j)(5) of this AD. Repeat the inspections at the applicable times specified in table 4 and table 5 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014.
(1) Where Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specifies a compliance time “after the original issue date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) Where Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specifies to contact Boeing for repair instructions: Before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (l) of this AD. Although Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specifies to contact Boeing for repair instructions, and specifies that action as Required for Compliance (RC), this AD requires repair as specified in this paragraph.
(3) Where note (e) of Figure 5 of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specifies to “Refer to Paragraph 3.B., Work Instructions, Table 2 for edge margin requirements,” operators must comply with Table 3 of paragraph 3.B., “Work Instructions,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, for edge margin requirements.
(4) Where the notes for fastener codes A and B in figures 9, 10, 11, and 12 of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, refer to “Paragraph 3.B., Work Instructions, Table 2” for edge margin requirements, operators must comply with Table 3 of paragraph 3.B., “Work Instructions,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, for edge margin requirements.
(5) Where note (e) of figures 6, 7, and 8 and step 1.a.(1) of Part 5 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specifies to “Refer to Paragraph 3.B., Work Instructions, Table 3 for edge margin requirements,” operators must comply with Table 3 of paragraph 3.B., “Work Instructions,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, for edge margin requirements.
Table 3 and Table 8 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1328, dated July 22, 2014, specify post-modification airworthiness limitation inspections in compliance to 14 CFR 25.571(a)(3) at the modified locations, which support compliance with 14 CFR 121.1109(c)(2) or 129.109(b)(2). As airworthiness limitations, these inspections are required by maintenance and operational rules. It is therefore unnecessary to mandate them in this AD. Deviations from these inspections require FAA approval, but do not require an alternative method of compliance.
